AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 800 PM EST THU JAN 15 2009 .SYNOPSIS/UPDATE... 00Z WATER VAPOR AND H4 RUC ANALYSIS CONTINUES TO SHOW A HIGHLY AMPLIFIED UPPER LEVEL PATTERN ACROSS NORTH AMERICA THIS EVENING. MAIN FEATURE OF NOTE IS THE LARGE AND DOMINANT LONGWAVE TROUGH COVERING MOST OF CENTRAL AND EASTERN NORTH AMERICA. EXTREMELY COLD ARCTIC AIR IS IN PLACE UNDER THIS TROUGH FROM THE NORTHERN PLAINS TO THE MIDWEST AND NORTHEASTERN STATES. TO THE WEST OF THIS TROUGH WE FIND AMPLIFIED RIDGING ALONG THE WEST COAST FROM BRITISH COLUMBIA SOUTH TO CALIFORNIA. OUR AREA RESIDES ON THE SOUTHERN PERIPHERY OF THE UPPER TROUGH OVER THE EASTERN U.S. SIGNIFICANT AMOUNTS OF SOUTHERN STREAM MOISTURE ARE BEING DRAWN UP ON THE EASTERN SIDE OF THE TROUGH AND RESULTING IN PERIODS OF HIGH LEVEL CIRRUS CANOPY OVERHEAD. DRY COLD FRONT WITH THE NEXT SURGE OF PROGRESSIVELY COLDER AND DRIER AIR IS CURRENTLY PROGRESSING SOUTH AND EAST ACROSS THE FORECAST AREA. AS OF 730 PM EST THIS FRONT WAS LOCATED ACROSS EXTREME SOUTHERN GA AND SOUTHWEST INTO THE FLORIDA PANHANDLE. SIGNIFICANT CHANGE IN AIRMASS BEHIND THIS FRONT. DEWPOINTS ACROSS THE FLORIDA BIG BEND AND COASTAL PANHANDLE ARE HOLDING IN THE UPPER 20S AND LOWER 30S...WHILE ONLY A SHORT DISTANCE TO THE NORTH INTO GA AND AL THE DEWPOINTS HAVE DROPPED INTO THE SINGLE DIGITS. THE FRONT IS NOW THROUGH DOTHAN AND ALBANY WITH DEWPOINTS CURRENTLY DROPPING THROUGH THE TEENS. MUCH COLDER AIR IS ALSO SEEN JUST TO OUR NORTH WITH READINGS FALLING THROUGH THE 30S AND UPPER 20S AS CLOSE AS CENTRAL GA/AL. LATEST 00Z SOUNDING PROFILE FROM BIRMINGHAM ACTUALLY NOW SHOWING A RECOGNIZABLE LOW LEVEL ARCTIC INVERSION PROFILE. THIS COLDER AND DRIER AIR WILL BE SLOWLY FILTERING IN FROM THE NORTH ALL NIGHT AND WILL BE QUITE NOTICEABLE ACROSS THE ENTIRE FORECAST AREA BY DAWN. CURRENT FORECAST STILL LOOKS ON TRACK FOR THE REST OF THE OVERNIGHT PERIOD WITH TEMPERATURES SLOWLY FALLING THROUGH THE 40S INTO THE 30S THROUGH MIDNIGHT...AND THEN CONTINUING TO FALL INTO THE MIDDLE/UPPER 20S FOR MOST LOCATIONS BY SUNRISE. WITH A TIGHT GRADIENT IN PLACE BEHIND THE DEPARTING FRONT WILL STILL EXPECT THE NORTHERLY WINDS TO HOLD IN THE 5 TO 10 MPH RANGE. WHEN COMBINED WITH THE COLD TEMPERATURES IN PLACE...THIS WINDS WILL RESULT IN WINDCHILL VALUES DROPPING INTO THE TEENS ACROSS THE NORTHERN HALF OF THE FORECAST AREA. EVEN FOR AREAS OF NORTH FLORIDA THE WINDCHILL VALUES TOWARD SUNRISE WILL BE APPROACHING 20F...SO BUNDLE UP IF YOU ARE HEADING OUT EARLY TOMORROW MORNING. ONE CHANGE TO THE GRIDS FOR THIS UPDATE WILL BE TO INCREASE THE CLOUDS DURING THE OVERNIGHT HOURS WITH THE THIN CIRRUS CANOPY STREAMING IN FROM THE SOUTHWEST. MODIFIED ARCTIC AIRMASS IN PLACE TOMORROW WILL RESULT IN A MOSTLY SUNNY...BUT COOL DAY...EVEN FOR JANUARY. HIGH TEMPS WILL BE HOLDING IN THE 40S FOR ALL BUT PERHAPS THE FAR SOUTHEAST BIG BEND...AND SETTING UP A LONG DURATION OF SUB-FREEZING TEMPERATURES FOR MANY SPOTS FRIDAY NIGHT INTO SATURDAY MORNING. SEE PREVIOUS DISCUSSION BELOW FOR MORE DETAILS. && .PREVIOUS DISCUSSION... AS HAS BEEN THE CASE OVER THE PAST FEW DAYS...THE MAIN FCST CONCERN WILL CONTINUE TO BE LOW TEMPERATURES ACROSS THE REGION ...AS THE COLDEST AIR OF THE SEASON AND WIDESPREAD HARD FREEZE IS STILL EXPECTED ON FRIDAY NIGHT AND SATURDAY MORNING. HOWEVER...THE POSSIBLE EXTREME COLD WITH LOWS IN THE LOWER TO MID TEENS THAT WAS EARLIER EVIDENT IN MANY OF THE SHORT RANGE MODELS IS APPEARING LESS LIKELY WITH TIME...AS THE POSITION OF THE RIDGE MAY BE TOO FAR TO OUR NE TO ALLOW FOR THE IDEAL RADIATIONAL COOLING CONDITIONS NEEDED FOR LOWS THIS COLD. IF THE SFC WINDS REMAIN AT 2-4 KTS FOR MUCH OF THE NIGHT...LOW TEMPERATURES MAY BOTTOM OUT IN THE UPPER TEENS TO LOWER 20S INLAND TO THE MID 20S NEAR THE COAST...SO WILL ADJUST TEMPS SLIGHTLY UPWARD ON THIS PACKAGE. WILL ALSO INITIATE A HARD FREEZE WATCH OVER ALL AREAS FOR FRIDAY NIGHT. FOR TONIGHT...THE COLD AIR ADVECTION WILL LIKELY BE STRONG ENOUGH TO SUPPORT A HARD FREEZE OVER ABOUT THE N 1/2 OF THE CWA...DESPITE NORTHERLY WINDS OF 5 TO 10 KTS...WHICH WILL ALSO LIKELY CREATE WIND CHILL ADVISORY CONDITIONS OVER THESE SAME AREAS (15 DEGREES OR BELOW) LATE TONIGHT. FURTHER TO THE SE...EXPECT ANOTHER WIDESPREAD LIGHT FREEZE WITH WIND CHILLS IN THE UPPER TEENS TO LOWER 20S. && .MARINE...A TIGHTENING PRESSURE GRADIENT AND STRONG COLD AIR ADVECTION EMERGING OVER THE COASTAL WATERS THIS EVENING BEHIND A COLD FRONT WILL RESULT IN WINDS INCREASE TO SCA LEVELS BY MIDNIGHT. WIND GUSTS MAY EVEN APPROACHING 30 KTS LATE TONIGHT INTO EARLY FRIDAY MORNING. HOW LONG THESE CONDITIONS WILL LAST IS MORE IN QUESTION...AND HAVE TENTATIVELY GONE WITH AN END TIME OF FRIDAY EVENING...ESPECIALLY ACROSS THE OFFSHORE ZONES DUE TO LINGERING SEAS. ANOTHER SURGE WILL BE POSSIBLE FRIDAY NIGHT...SO THIS MAY HAVE TO BE ADJUSTED AT A LATER TIME. && .AVIATION...UNLIMITED CIGS/VIS WILL CONTINUE THROUGH SATURDAY... OUTSIDE OF ANY LOCAL SMOKE PLUMES THAT DEVELOP. NORTHWEST WINDS AROUND 10 KT WILL CONTINUE THROUGH FRIDAY AFTERNOON...THEN DIMINISH BY FRIDAY EVENING. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 28 48 17 54 27 / 0 0 0 0 10 PANAMA CITY 30 49 24 54 36 / 0 0 0 0 10 DOTHAN 24 44 20 52 33 / 0 0 0 0 10 ALBANY 24 44 20 51 29 / 0 0 0 0 10 VALDOSTA 28 49 17 54 28 / 0 0 0 0 10 CROSS CITY 28 51 19 58 29 / 0 0 0 0 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...RED FLAG WARNING FROM 10 AM TO 5 PM CST FRIDAY FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY...HOUSTON. RED FLAG WARNING FROM 10 AM TO 4 PM CST SATURDAY FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY...HOUSTON. HARD FREEZE WATCH FROM FRIDAY EVENING THROUGH SATURDAY MORNING FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY... HOUSTON. HARD FREEZE WARNING FROM 1 AM TO 7 AM CST FRIDAY FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY...HOUSTON. WIND CHILL ADVISORY FROM 1 AM TO 7 AM CST FRIDAY FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY...HOUSTON. GA...RED FLAG WARNING FROM 11 AM TO 6 PM EST FRIDAY FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...BROOKS...CALHOUN... CLAY...COLQUITT...COOK...DECATUR...DOUGHERTY...EARLY... GRADY...IRWIN...LANIER...LEE...LOWNDES...MILLER... MITCHELL...QUITMAN...RANDOLPH...SEMINOLE...TERRELL... THOMAS...TIFT...TURNER...WORTH. RED FLAG WARNING FROM 11 AM TO 5 PM EST SATURDAY FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...BROOKS... CALHOUN...CLAY...COLQUITT...COOK...DECATUR...DOUGHERTY... EARLY...GRADY...IRWIN...LANIER...LEE...LOWNDES...MILLER... MITCHELL...QUITMAN...RANDOLPH...SEMINOLE...TERRELL... THOMAS...TIFT...TURNER...WORTH. HARD FREEZE WATCH FROM FRIDAY EVENING THROUGH SATURDAY MORNING FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN... BROOKS...CALHOUN...CLAY...COLQUITT...COOK...DECATUR... DOUGHERTY...EARLY...GRADY...IRWIN...LANIER...LEE... LOWNDES...MILLER...MITCHELL...QUITMAN...RANDOLPH... SEMINOLE...TERRELL...THOMAS...TIFT...TURNER...WORTH. HARD FREEZE WARNING FROM 2 AM TO 8 AM EST FRIDAY FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...CALHOUN... CLAY...COLQUITT...COOK...DOUGHERTY...EARLY...IRWIN...LEE... MILLER...MITCHELL...QUITMAN...RANDOLPH...TERRELL...TIFT... TURNER...WORTH. WIND CHILL ADVISORY FROM 2 AM TO 8 AM EST FRIDAY FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...CALHOUN... CLAY...COLQUITT...COOK...DOUGHERTY...EARLY...IRWIN...LEE... MILLER...MITCHELL...QUITMAN...RANDOLPH...TERRELL...TIFT... TURNER...WORTH. FL...RED FLAG WARNING FROM 11 AM EST /10 AM CST/ TO 6 PM EST /5 PM CST/ FRIDAY FOR THE FOLLOWING ZONES: BAY...CALHOUN... COASTAL WALTON...DIXIE...FRANKLIN...GADSDEN...GULF... HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE... LEON...LIBERTY...MADISON...TAYLOR...WAKULLA...WASHINGTON. HARD FREEZE WATCH FROM FRIDAY EVENING THROUGH SATURDAY MORNING FOR THE FOLLOWING ZONES: BAY...CALHOUN...COASTAL WALTON... DIXIE...FRANKLIN...GADSDEN...GULF...HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE...LEON...LIBERTY... MADISON...TAYLOR...WAKULLA...WASHINGTON. RED FLAG WARNING FROM 9 AM EST /8 AM CST/ TO 7 PM EST /6 PM CST/ SATURDAY FOR THE FOLLOWING ZONES: BAY...CALHOUN...COASTAL WALTON...DIXIE...FRANKLIN...GADSDEN...GULF...HOLMES... INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE...LEON... LIBERTY...MADISON...TAYLOR...WAKULLA...WASHINGTON. GM...SMALL CRAFT ADVISORY UNTIL 7 PM EST FRIDAY FOR ALL NEARSHORE AND OFFSHORE MARINE ZONES BETWEEN DESTIN FLORIDA AND THE MOUTH OF THE SUWANNEE RIVER. && $$ SYNOPSIS/UPDATE/MARINE...MROCZKA PREVIOUS DISCUSSION...GOULD AVIATION...FOURNIER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1146 AM CST FRI JAN 16 2009 .DISCUSSION... ISSUED 1037 AM CST FRI JAN 16 2009 WILL BE CANCELLING THE WIND CHILL WARNINGS AND ADVISORIES LATE THIS MORNING ACROSS CENTRAL IL. ALL THE WIND CHILLS HAD MODIFIED ABOVE MINUS 15F EXCEPT BLOOMINGTON WAS STILL AT MINUS 25F. COOLED THE HIGHS A DEGREE OR TWO TODAY ESPECIALLY OVER DEEPER SNOW COVER FROM I-74 NE WITH UPPER SINGLE DIGITS. HIGHS NEAR 15F FROM SPRINGFIELD AND ROBINSON SW. MOSTLY SUNNY SKIES WITH PASSING MID/HIGH CLOUDS ESPECIALLY SW AREAS. SOUTH WINDS 5 TO 10 MPH. LATE MORNING SURFACE MAP SHOWS STRONG 1045 MB ARCTIC HIGH PRESSURE NEAR EVANSVILLE IN THE LOWER OHIO VALLEY AND RIDGING ACROSS IL. AIR TEMPERATURES WERE ZERO TO 10F FROM DECATUR NORTH WITH BLOOMINGTON COLDEST AT MINUS 10F WHILE ZERO TO 10 ABOVE SOUTH OF DECATUR. LIGHT SOUTH TO CALM WINDS. ARCTIC HIGH PRESSURE WEAKENS TO 1040 MB OVER SOUTHERN OHIO BY 00Z/6 PM WHILE A WEAK UPPER LEVEL DISTURBANCES MOVES SE ACROSS MO KEEPING MORE CLOUDS AND LIGHT SNOW CHANCES SW OF CENTRAL IL TODAY. HIGHS WILL RANGE FROM UPPER SINGLE DIGITS NEAR AND NEAR 15 SW. HUETTL && .AVIATION... ISSUED 1145 AM CST FRI JAN 16 2009 VFR CONDITIONS SHOULD PREVAIL ACROSS THE CENTRAL ILLINOIS TERMINALS THROUGH 18Z/SAT. STRONG 1044 MB ARCTIC HIGH PRESSURE OVER THE LOWER OHIO VALLEY AND RIDGING OVER IL AT MIDDAY WILL MOVE EAST TOWARD THE MID ATLANTIC COAST BY 18Z/SAT. 1010 MB LOW PRESSURE OVER NORTHERN SASKATCHEWAN AND SHORT WAVE OVER ALBERTA WILL RACE SE INTO WI BY 18Z/SAT...KEEPING THE LIGHT SNOW AND LOWER CLOUDS NORTH OF CENTRAL IL THOUGH APPROACHING PIA BY 18Z/SAT. MID LEVEL CLOUDS SW OF SPI OVER SW IL AND MO WILL TRACE SE THIS AFTERNOON AND WILL BE CLOSE TO SPI. HAVE THESE CLOUDS MOVING EAST FROM SPI TO BMI AND CMI BY MID EVENING FROM 02Z TO 04Z. LIGHT SSW WINDS BECOME SOUTH 10 TO 15 KTS THIS EVENING AND INCREASE TO 15 TO 20 KTS WITH GUSTS OF 20 TO 25 KTS BY SAT MORNING DUE TO INCREASING PRESSURE GRADIENT. HUETTL && .PREV DISCUSSION... ISSUED 225 AM CST FRI JAN 16 2009 CENTER OF ARCTIC HIGH PRESSURE DRIFTING ACROSS CENTRAL AND SOUTHERN ILLINOIS EARLY THIS MORNING. WINDS HAVE BECOME RATHER LIGHT IN MOST AREAS...BUT WERE STILL LOCALLY CLOSE TO 10 MPH ACROSS SOME OF THE NORMALLY BREEZIER AREAS OF THE EAST CENTRAL CWA. TEMPERATURES IN THE TEENS BELOW ZERO WERE WIDESPREAD NORTH OF A BEARDSTOWN TO PARIS LINE...AND HAS BEEN FLUCTUATING IN THE 20 BELOW RANGE IN THE EXTREME NORTHERN CWA AROUND GALESBURG AND LACON. MOS GUIDANCE WAS NO HELP IN INITIALIZING TEMPERATURES AT THE START OF THE FORECAST PERIOD...WITH ITS TEMPERATURES SEVERAL DEGREES TOO WARM RIGHT OFF THE BAT. BEGAN WITH USING RUC MODEL HOURLY TEMPERATURES BEFORE TRANSITIONING TOWARD MET MOS GUIDANCE. ONCE THE ARCTIC AIR LEAVES LATER TODAY...FORECAST ISSUES MAINLY INVOLVE CLIPPER SYSTEMS THIS WEEKEND AND EARLY NEXT WEEK...ALONG WITH EXTENT OF WARMUP. SHORT TERM...TODAY THROUGH MONDAY... HIGH PRESSURE TO MOVE INTO THE OHIO VALLEY LATER THIS MORNING...WITH WINDS BECOMING SOUTHERLY. THIS WILL FINALLY BRING AN END TO THE BRUTAL COLD. EXISTING WIND CHILL WARNING/ADVISORY WILL CONTINUE UNTIL ITS NATURAL EXPIRATION AT NOON. MODELS HINTING AT SOME WARM AIR ADVECTION PRECIPITATION...BUT THIS IS EXPECTED TO STAY WEST OF THE MISSISSIPPI RIVER. LOW TEMPERATURES TONIGHT EXPECTED TO BE DURING THE EVENING...WITH RISING TEMPERATURES OVERNIGHT AS WINDS PICK UP. RELATIVELY MILD CONDITIONS EXPECTED ON SATURDAY WITH HIGHS IN THE UPPER 20S TO MID 30S...COOLEST OVER THE SNOWPACK IN THE NORTHERN CWA. NEXT CLIPPER SYSTEM TO DIVE SOUTHEAST OUT OF CANADA OVERNIGHT. MODELS SIMILAR IN BRINGING ASSOCIATED COLD FRONT ACROSS THE CWA SATURDAY AFTERNOON AND EVENING...ALTHOUGH ECMWF MODEL A BIT FURTHER EAST WITH THE TRACK OF THE PARENT LOW ACROSS THE GREAT LAKES REGION. EXPECTING THE MEASURABLE PRECIPITATION WITH THIS SYSTEM TO REMAIN TO OUR NORTH AND NORTHEAST...ALTHOUGH A FEW FLURRIES MAY BE POSSIBLE NORTH OF I-74. NOT MUCH CHANGE IN TEMPERATURE EXPECTED SUNDAY BEHIND THE FRONT...DESPITE THE NORTHWEST FLOW. MODELS IN LESS AGREEMENT ABOUT THE NEXT DISTURBANCE SUNDAY NIGHT AND MONDAY. GFS WAS MUCH SLOWER THAN THE NAM OR ECMWF MODELS WITH THIS FEATURE...AND TAKES THE SYSTEM DUE SOUTH OUT OF WESTERN MINNESOTA AND COMPLETELY MISSING THE FORECAST AREA. DISCOUNTED THIS SCENARIO AND WENT WITH A BLEND OF THE OTHER TWO MODELS...WHICH SWEEPS THE FRONT THROUGH THE CWA BETWEEN 06-12Z MONDAY. HOWEVER...PASSAGE OF THIS FRONT IS EXPECTED TO BE DRY...AND TEMPERATURES AGAIN WILL CHANGE LITTLE FROM THE PREVIOUS DAY. LONG TERM...TUESDAY THROUGH THURSDAY... NO CHANGES MADE TO THIS PART OF THE FORECAST. UPPER RIDGE ACROSS THE WESTERN U.S. EXPECTED TO FINALLY BREAK DOWN BY THE MIDDLE OF THE WEEK...WITH UPPER FLOW EXPECTED TO COME MORE OUT OF WESTERN CANADA INSTEAD OF THE NORTHERN TERRITORIES. BY THE END OF THE WEEK...MORE OF A SPLIT UPPER FLOW PATTERN IS EXPECTED. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 556 AM CST FRI JAN 16 2009 .DISCUSSION... ISSUED 225 AM CST FRI JAN 16 2009 CENTER OF ARCTIC HIGH PRESSURE DRIFTING ACROSS CENTRAL AND SOUTHERN ILLINOIS EARLY THIS MORNING. WINDS HAVE BECOME RATHER LIGHT IN MOST AREAS...BUT WERE STILL LOCALLY CLOSE TO 10 MPH ACROSS SOME OF THE NORMALLY BREEZIER AREAS OF THE EAST CENTRAL CWA. TEMPERATURES IN THE TEENS BELOW ZERO WERE WIDESPREAD NORTH OF A BEARDSTOWN TO PARIS LINE...AND HAS BEEN FLUCTUATING IN THE 20 BELOW RANGE IN THE EXTREME NORTHERN CWA AROUND GALESBURG AND LACON. MOS GUIDANCE WAS NO HELP IN INITIALIZING TEMPERATURES AT THE START OF THE FORECAST PERIOD...WITH ITS TEMPERATURES SEVERAL DEGREES TOO WARM RIGHT OFF THE BAT. BEGAN WITH USING RUC MODEL HOURLY TEMPERATURES BEFORE TRANSITIONING TOWARD MET MOS GUIDANCE. ONCE THE ARCTIC AIR LEAVES LATER TODAY...FORECAST ISSUES MAINLY INVOLVE CLIPPER SYSTEMS THIS WEEKEND AND EARLY NEXT WEEK...ALONG WITH EXTENT OF WARMUP. SHORT TERM...TODAY THROUGH MONDAY... HIGH PRESSURE TO MOVE INTO THE OHIO VALLEY LATER THIS MORNING...WITH WINDS BECOMING SOUTHERLY. THIS WILL FINALLY BRING AN END TO THE BRUTAL COLD. EXISTING WIND CHILL WARNING/ADVISORY WILL CONTINUE UNTIL ITS NATURAL EXPIRATION AT NOON. MODELS HINTING AT SOME WARM AIR ADVECTION PRECIPITATION...BUT THIS IS EXPECTED TO STAY WEST OF THE MISSISSIPPI RIVER. LOW TEMPERATURES TONIGHT EXPECTED TO BE DURING THE EVENING...WITH RISING TEMPERATURES OVERNIGHT AS WINDS PICK UP. RELATIVELY MILD CONDITIONS EXPECTED ON SATURDAY WITH HIGHS IN THE UPPER 20S TO MID 30S...COOLEST OVER THE SNOWPACK IN THE NORTHERN CWA. NEXT CLIPPER SYSTEM TO DIVE SOUTHEAST OUT OF CANADA OVERNIGHT. MODELS SIMILAR IN BRINGING ASSOCIATED COLD FRONT ACROSS THE CWA SATURDAY AFTERNOON AND EVENING...ALTHOUGH ECMWF MODEL A BIT FURTHER EAST WITH THE TRACK OF THE PARENT LOW ACROSS THE GREAT LAKES REGION. EXPECTING THE MEASURABLE PRECIPITATION WITH THIS SYSTEM TO REMAIN TO OUR NORTH AND NORTHEAST...ALTHOUGH A FEW FLURRIES MAY BE POSSIBLE NORTH OF I-74. NOT MUCH CHANGE IN TEMPERATURE EXPECTED SUNDAY BEHIND THE FRONT...DESPITE THE NORTHWEST FLOW. MODELS IN LESS AGREEMENT ABOUT THE NEXT DISTURBANCE SUNDAY NIGHT AND MONDAY. GFS WAS MUCH SLOWER THAN THE NAM OR ECMWF MODELS WITH THIS FEATURE...AND TAKES THE SYSTEM DUE SOUTH OUT OF WESTERN MINNESOTA AND COMPLETELY MISSING THE FORECAST AREA. DISCOUNTED THIS SCENARIO AND WENT WITH A BLEND OF THE OTHER TWO MODELS...WHICH SWEEPS THE FRONT THROUGH THE CWA BETWEEN 06-12Z MONDAY. HOWEVER...PASSAGE OF THIS FRONT IS EXPECTED TO BE DRY...AND TEMPERATURES AGAIN WILL CHANGE LITTLE FROM THE PREVIOUS DAY. LONG TERM...TUESDAY THROUGH THURSDAY... NO CHANGES MADE TO THIS PART OF THE FORECAST. UPPER RIDGE ACROSS THE WESTERN U.S. EXPECTED TO FINALLY BREAK DOWN BY THE MIDDLE OF THE WEEK...WITH UPPER FLOW EXPECTED TO COME MORE OUT OF WESTERN CANADA INSTEAD OF THE NORTHERN TERRITORIES. BY THE END OF THE WEEK...MORE OF A SPLIT UPPER FLOW PATTERN IS EXPECTED. GEELHART && .AVIATION... ISSUED 556 AM CST FRI JAN 16 2009 VFR CONDITIONS EXPECTED THROUGH THE 12Z TAF PERIOD. ARCTIC HIGH PRESSURE WILL PUSH OFF THE EAST THIS MORNING WITH WINDS TURNING SOUTHERLY. AN CLIPPER SYSTEM WILL APPROACH FROM THE NORTHWEST LATER TODAY AND TONIGHT...WITH VFR CEILINGS GRADUALLY LOWERING AND WIND SPEEDS INCREASING THROUGH THE TEENS. BAK && .ILX WATCHES/WARNINGS/ADVISORIES... WIND CHILL ADVISORY UNTIL NOON CST TODAY FOR ILZ049>057-061>063- 066>068-071>073. WIND CHILL WARNING UNTIL NOON CST TODAY FOR ILZ027>031-036>038- 040>048. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 1042 PM CST WED JAN 14 2009 .DISCUSSION... 656 PM CST WINDS ARE BEGINNING TO DIMINISH OVER OUR NORTHWESTERN COUNTIES AS STRONGEST PRESSURE RISES CONTINUE TO MAKE THEIR WAY SOUTHEASTWARD. WITH WINDS AT MOST LOCATIONS NOW DOWN TO 10KT OR LESS WILL BEGIN TO TRIM SOME OF THE COUNTIES OFF THE WINTER WEATHER ADVISORY. ALSO...INTENSE LAKE EFFECT SNOW PLUME CONTINUES TO MIGRATE SLOWLY EASTWARD AS INDIVIDUAL ELEMENTS WITHIN THE BAND MOVE SOUTHWARD. HAVE RECEIVED NUMEROUS REPORTS OF ZERO VISIBILITIES WITH WHITE-OUT CONDITIONS AND SNOWFALL RATES OF 1-2 INCHES IN AN HOUR OR LESS. THANKFULLY...MULTIPLE MESOLOWS HAVE BEEN DEVELOPING WITHIN THE LAKE EFFECT PLUME AND THESE SMALL SCALE CIRCULATIONS HAVE KEPT THE LINE FAIRLY KINKY AND GENERALLY KEPT DURATION OF THE MOST INTENSE SNOW FAIRLY SHORT. PLUME HAS SHIFTED EAST OF LAKE COUNTY AND WILL BE DOWNGRADING THE WARNING TO A WINTER WX ADVISORY SHORTLY. SUSPECT THAT PRIOR TO 9PM WILL BE ABLE TO SHAVE ANOTHER BATCH OF COUNTIES OUT OF THE WINTER WEATHER ADVISORY AS WINDS CONTINUE TO DIMINISH. IZZI && .AVIATION... 1033 PM CST 06Z TAFORS...RIDGE OF HI PRES EXTENDS FM SASK ACROSS THE DAKOTAS...MID MO AND MD MS VALLEYS LATE THIS EVE. SOUTHERN EXTENT OF RIDGE TO SHIFT EASTWARD ACROSS THE OH AND TN VALLEYS DURING THU AFTERNOON AND EVE MAINTAINING NW SFC WIND. FAIRLY STRONG PRES GRADIENT ACROSS THE LOCAL TERMINALS THOUGH IS SFC PARTIALLY DECOUPLED DUE TO VERY COLD DRY AIR...FRESH SNOW COVER AND CLEAR SKY. WIND EXPECTED TO PICK UP A BIT DIURNALLY THU MORN. ANOTHER SHORT WAVE CURRENTLY DROPPING SSE FM MANITOBA INTO FAR WESTERN ONT WITH PATCHY MID CLOUDS. DISTURBANCE TO TURN MORE SOUTHEASTWARD AS IT DROPS FURTHER INTO THE UPPER TROF AND WHILE MAY BE A FEW CLOUDS SEEN OVR NORTHERN IL MAIN AREA OF MID CLOUDINESS EXPECTED TO MOVE INTO THE CENTRAL GRTLKS DURING THE DAY THU. TRS && .MARINE... 1040 PM CST UPDATE...HAVE CANCELED GALE WARNING AS OBSERVATIONS BELOW THRESHOLD AND NO SUPPORT FOR GALE FORCE WINDS SEEN IN 00Z GRB RAOB...MKX- LOT- ORD- MDW VAD WINDS...ACARS...OR 00Z NAM AND RUC MODEL OUTPUT. 212 PM...LOW PRESSURE MOVING EAST ACROSS THE OHIO VALLEY THIS AFTERNOON WILL MOVE OFF THE ATLANTIC COAST THURSDAY MORNING. LARGE STRONG ARCTIC HIGH PRESSURE WILL BUILD ACROSS THE PLAINS TONIGHT THEN SPREAD SOUTHEAST ACROSS THE OHIO AND TENNESSEE VALLEYS THURSDAY AND THURSDAY NIGHT. A PERIOD OF GALES IS LIKELY ACROSS THE SOUTHERN HALF OF LAKE MICHIGAN TONIGHT AS THE GRADIENT TIGHTENS BETWEEN THESE TWO FEATURES. WINDS DIMINISH TO 30 KNOTS BY MORNING BUT GRADIENT LOOKS LIKE IT WILL MAINTAIN 25-30KTS THRU FRIDAY MORNING BEFORE IT FINALLY WEAKENS. WINDS THEN QUICKLY TURN SOUTHERLY FRIDAY NIGHT AS ANOTHER CLIPPER SYSTEM MOVES ACROSS THE WESTERN LAKES WITH WINDS TURNING BACK NORTHERLY SATURDAY. CMS && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER WEATHER ADVISORY...ILZ033-ILZ039 UNTIL MIDNIGHT THURSDAY. WIND CHILL WARNING...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010- ILZ011-ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022- ILZ023-ILZ032-ILZ033-ILZ039 UNTIL NOON FRIDAY. IN...WIND CHILL WARNING...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL NOON FRIDAY. WINTER STORM WARNING...INZ002 UNTIL MIDNIGHT THURSDAY. WINTER WEATHER ADVISORY...INZ010-INZ011-INZ019 UNTIL MIDNIGHT THURSDAY. LM...HEAVY FREEZING SPRAY WARNING...LMZ080-LMZ261-LMZ362-LMZ364- LMZ366-LMZ563-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 6 AM SATURDAY. HEAVY FREEZING SPRAY WARNING...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 10 AM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO BURNS HARBOR UNTIL 3 AM THURSDAY. HEAVY FREEZING SPRAY WARNING...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOO SMALL CRAFT ADVISORY...NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN UNTIL 9 P && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 736 PM EST FRI JAN 16 2009 .UPDATE... GIVEN CONTINUED CRASHING TEMPERATURES...WILL NEED TO UPGRADE WIND CHILL ADVISORY TO WARNING AS FWA/GSH ALREADY HAVE WIND CHILLS AT -25F AS OF 7PM AND MORE LOCATIONS WILL SEE WIND CHILLS FALL TO BETWEEN -25 AND -35 TONIGHT. HAVE LOWERED TEMPS A FEW DEGREES MORE...GENERALLY BETWEEN -10 TO -15 WITH A FEW SITES LIKELY FALLING A LITTLE LOWER THAN THIS. UPDATED GRIDS/PRODUCTS ARE OUT. && .PREV DISCUSSION... /ISSUED 658 PM EST FRI JAN 16 2009/ UPDATE... UPDATE TO CUT TEMPERATURES THIS EVENING AS WE/LL HAVE SOME IDEAL RADIATIONAL COOLING CONDITIONS THROUGH THE FIRST HALF OF THE OVERNIGHT BEFORE INCREASING HIGH CLOUDS HELP TURN TEMPS AROUND AFTER MIDNIGHT. DEWPOINTS IN THE MINUS TEENS SUGGEST PLENTY OF ROOM TO DROP. RUC13 HAS THE BEST HANDLE ON THIS THIS EVENING BUT AM A LITTLE FEARFUL THAT IN SOME SPOTS IT MAY STILL BE TOO WARM. OVER MUCH OF THE AREA...THIS MEANS ANOTHER NIGHT OF -10 TO -15F. IN ADDITION...THE SOMEWHAT COLDER TEMPS SHOULD PROLONG ADV LEVEL WIND CHILLS TONIGHT SO HAVE EXTENDED THE WC ADVISORY THROUGH 12Z AND WILL HAVE TO WATCH TEMPS LATE THIS EVENING AS WE WILL BE NEAR WC WARNING CRITERIA FOR THE OVERNIGHT. PREV DISCUSSION... /ISSUED 627 PM EST FRI JAN 16 2009/ AVIATION... VFR ATTM UNDER SKC WITH SOUTHWESTERLY WINDS 5-10KTS. EXPECT VFR TO PERSIST THROUGH THE OVERNIGHT WITH GRADUALLY THICKENING/LOWERING CLOUDS LATE TONIGHT. ON SATURDAY...A LOW VFR DECK SHOULD MOVE IN AROUND DAYBREAK. CAN/T RULE OUT SOME SHSN AS THIS MOVES IN...BUT EXPECT MOST IF NOT ALL OF THE SNOW TO REMAIN NORTH AND EAST OF THE TAF SITES DURING THE MORNING WITH VFR CONDITIONS PREVAILING. BY AFTERNOON...MVFR CIGS WITH LIGHT SNOW WILL MOVE INTO SBN. LESS CONFIDENT IN THEM REACHING FWA BY THE END OF THE TAF PERIOD SO HAVE INCLUDED THE MVFR POSSIBILITY AS A PROB30 AT THIS TIME. THE SOUTHWESTERLY WINDS THIS EVENING WILL BECOME SOUTHERLY AND STRENGTHEN TO 10-15KTS OVERNIGHT AND THEN TO 18G26KTS DURING THE MORNING ON SATURDAY. WINDS WILL BECOME MORE SOUTH SOUTHWESTERLY AND MAY SUBSIDE A LITTLE TOWARDS THE END OF THE TAF PERIOD BUT ARE LIKELY TO REMAIN AROUND 15KTS. PREV DISCUSSION... /ISSUED 336 PM EST FRI JAN 16 2009/ SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT MAIN FOCUS IN THE SHORT TERM IS TEMPS/WIND CHILLS TONIGHT AND SN/FZDZ CHANCES SAT INTO SAT NIGHT. WINDS DROPPING TO NEAR 5 KNOTS AND MAINLY CLEAR SKIES EARLY THIS EVENING WILL PROBABLY ALLOW TEMPS TO PLUMMET BACK TOWARDS -10F THIS EVENING. EXPECT SOME WARMING AFTER MIDNIGHT AS SOUTHWESTERLY LL FLOW DEVELOPS ON BACKSIDE OF 1040MB ARCTIC HIGH WHICH WILL SHIFT EASTWARD INTO THE CENTRAL APPS/MIDDLE ATLANTIC. THEREFORE...HAVE NON DIURNAL TEMPS TONIGHT WITH VALUES HOPEFULLY WARMING INTO THE SINGLE DIGITS ABV ZERO BY 12Z SAT. COLD TEMPS COMBINED WITH LIGHT SSW SFC WINDS WILL KEEP APPARENT TEMPS IN THE -15 TO -25F RANGE...SO WENT WITH A WIND CHILL ADVISORY FOR THE ENTIRE CWA THROUGH 09Z SATURDAY. SHORTWAVE CURRENTLY OVER NRN FRINGE OF HIGHLY AMPLIFIED EASTERN PAC/WESTERN NOAM RIDGE WILL RAPIDLY SLIDE SEWD INTO THE UPPER MIDWEST LATE TONIGHT...AND THE GREAT LAKES SATURDAY INTO SATURDAY NIGHT. FAVOR FARTHER NORTH AND DRIER NAM/SREF/ECMWF SOLUTIONS OVER THE GFS IN TRACKING ASSOCIATED SFC REFLECTION INTO CENTRAL LOWER MICHIGAN BY SATURDAY EVENING...AS THE NAM HAS PERFORMED BETTER FOR THE LAST SEVERAL CLIPPER EVENTS WHEN COMPARED TO THE GFS. WAA/ISENTROPIC UPGLIDE WITH 40-50KT CROSS ISOBARIC FLOW AND 2-3 G/KG MOISTURE SURGE OVER ARCTIC DOME DOES SUPPORT A BAND OF LIGHT/MODERATE SNOW PIVOTING EAST THROUGH AT LEAST FAR NORTHERN AREAS ON SATURDAY. BETTER CHANCES FOR DECENT SNOW ACCUMULATIONS IN THE 1-3 INCH RANGE APPEAR POSSIBLE IN THE COLDWATER/HILLSDALE AREAS CLOSER TO THE DEEPER MOISTURE AND BETTER DYNAMICS. MAYBE A COATING TO AN INCH IN CENTRAL AREAS WITH LITTLE IF ANY ACCUMULATION IN THE SOUTHWEST. ADDED FREEZING DRIZZLE MENTION TO WESTERN/SOUTHERN AREAS SAT AFTN/EVE AS NAM FCST SOUNDINGS CONSISTENT IN SHOWING LACK OF MOISTURE IN THE ICE PRODUCTION ZONE WITH LL MOISTURE TRAPPED UNDER A LOWERING INVERSION. SLICK SPOTS ON AREA ROADS WILL BE POSSIBLE IF THIS MATERIALIZES. OTHERWISE... IT WILL FEEL BALMY OUT BY TOMORROW AFTERNOON WITH HIGHS RECOVERING ALL THE WAY BACK INTO THE 20S. LARGE SCALE LIFT PER 5-3H Q-VECTOR CONVERGENCE AND DIFF PVA AHEAD OF H5 TROUGH AXIS SHIFTS EAST BY 00Z SUN WITH JUST LINGERING LIGHT SNOW SHOWERS/FLURRIES/PATCHY FZDZ SAT EVE. CAA BEHIND SYSTEM WILL ALLOW FOR LAKE EFFECT SNOW SHOWERS TO DEVELOP ACROSS THE FAR NW LATE SATURDAY NIGHT. CONTINUED WITH LIKELY POPS IN THESE AREAS 06-12Z SUN. DELTA T/S OF 15-18 AND SATURATION WITHIN THE DGZ INDICATE POTENTIAL FOR SOME SNOW ACCUMULATION WITH LAKE EFFECT. HOWEVER...INVERSION NEAR 5KFT AND UNFAVORABLE 280/290 DEGREE FETCH DO NOT FAVOR ACCUMS ABOVE 2 INCHES. LONG TERM... SUNDAY THROUGH FRIDAY... LONG TERM WILL SEE CHANGES TO LARGE SCALE UPPER AIR PATTERN OVER THE CONUS AS WESTERN RIDGE BEGINS TO BREAK DOWN AS STRONG PACIFIC ENERGY UNDERCUTS IT. TROUGHINESS OVER THE EASTERN CONUS EXPECTED TO PERSIST AS NORTHERN BRANCH OF UPPER JET REMAINS DOMINANT AND CONTINUES TO DIVE INTO THE GREAT LAKES. ECMWF AND GFS HAVE SIGNIFICANTLY DIFFERENT SOLUTIONS IN HOW THIS PATTERN WILL EVOLVE AND THEREFORE A LARGE DEGREE OF UNCERTAINTY IN THE LATTER PART OF THE LONG TERM GRIDS. BEGINNING OF PERIOD WILL SEE CLIPPER SYSTEM CROSSING AND EXITING THE AREA WITH CHANCES FOR LIGHT SNOW SUNDAY. LAKE EFFECT POTENTIAL CONTINUES BEHIND CLIPPER SUNDAY AFTERNOON AND SUNDAY NIGHT...INTO MONDAY MORNING. THIS IS AN INTERESTING SETUP AND HAS POTENTIAL FOR A DECENT SNOW EVENT ASSUMING MOISTURE REMAINS IN PLACE. LIMITING FACTOR WILL BE TRANSITORY NATURE OF BAND AND DEPTH OF MOISTURE. DUE TO LIMITING FACTORS AND QUESTIONS ON BAND PLACEMENT HAVE CONTINUED WITH HIGH CHANCE POPS RATHER THAN LIKELY OR CATEGORICAL. LATEST NAM INDICATING EVOLUTION INTO SINGLE BAND INTO FAR WESTERN COUNTIES BY MONDAY MORNING. NAM HAS ALSO STRUGGLED WITH RECENT LAKE EVENTS IN THESE PERIODS SO STILL SOME DOUBT. STAYED CLOSE TO A BLEND OF PREVIOUS GRIDS AND HPC FOR MIDDLE TO LATE PART OF LONG TERM GIVEN MODEL DIFFERENCES. ECMWF HAS BEEN MODEL OF CHOICE MOST OF WINTER AND IT IS NOT AS AGGRESSIVE WITH MID WEEK WARM UP AS GFS...WHICH SHOWS 850MB TEMPS WELL ABOVE CLIMO FOR MID JANUARY. HAVE DOUBTS AT THIS TIME ON SUCH A PRONOUNCED WARM UP GIVEN STRONG ARCTIC AIR MASS IN PLACE AND DEEP SNOW PACK THAT EXISTS. PREFER COOLER ECMWF. GRIDS AND HPC IN THE MIDDLE AND PREFER TO KEEP IT THAT WAY UNTIL CLEAR PATTERN EVOLVES. ECMWF SHOWING ANOTHER COLD ARCTIC FRONT LATE IN THE PERIOD. GFS DEVELOPING A RATHER STRONG CYCLONE BY DAY 7. AGAIN WILL STAY IN MIDDLE GROUND AND SIDE WITH HPC FOR COLLABORATION GIVEN WIDE VARIETY OF POSSIBLE SOLUTIONS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL WARNING UNTIL 7 AM EST /6 AM CST/ SATURDAY FOR INZ003>009-012>018-020-022>027-032>034. MI...WIND CHILL WARNING UNTIL 7 AM EST SATURDAY FOR MIZ077>081. OH...WIND CHILL WARNING UNTIL 7 AM EST SATURDAY FOR OHZ001-002-004- 005-015-016-024-025. LM...NONE. && $$ SHORT TERM...STEINWEDEL LONG TERM...LASHLEY AVIATION...ARNOTT UPDATE...ARNOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 658 PM EST FRI JAN 16 2009 .UPDATE... UPDATE TO CUT TEMPERATURES THIS EVENING AS WE/LL HAVE SOME IDEAL RADIATIONAL COOLING CONDITIONS THROUGH THE FIRST HALF OF THE OVERNIGHT BEFORE INCREASING HIGH CLOUDS HELP TURN TEMPS AROUND AFTER MIDNIGHT. DEWPOINTS IN THE MINUS TEENS SUGGEST PLENTY OF ROOM TO DROP. RUC13 HAS THE BEST HANDLE ON THIS THIS EVENING BUT AM A LITTLE FEARFUL THAT IN SOME SPOTS IT MAY STILL BE TOO WARM. OVER MUCH OF THE AREA...THIS MEANS ANOTHER NIGHT OF -10 TO -15F. IN ADDITION...THE SOMEWHAT COLDER TEMPS SHOULD PROLONG ADV LEVEL WIND CHILLS TONIGHT SO HAVE EXTENDED THE WC ADVISORY THROUGH 12Z AND WILL HAVE TO WATCH TEMPS LATE THIS EVENING AS WE WILL BE NEAR WC WARNING CRITERIA FOR THE OVERNIGHT. && .PREV DISCUSSION... /ISSUED 627 PM EST FRI JAN 16 2009/ AVIATION... VFR ATTM UNDER SKC WITH SOUTHWESTERLY WINDS 5-10KTS. EXPECT VFR TO PERSIST THROUGH THE OVERNIGHT WITH GRADUALLY THICKENING/LOWERING CLOUDS LATE TONIGHT. ON SATURDAY...A LOW VFR DECK SHOULD MOVE IN AROUND DAYBREAK. CAN/T RULE OUT SOME SHSN AS THIS MOVES IN...BUT EXPECT MOST IF NOT ALL OF THE SNOW TO REMAIN NORTH AND EAST OF THE TAF SITES DURING THE MORNING WITH VFR CONDITIONS PREVAILING. BY AFTERNOON...MVFR CIGS WITH LIGHT SNOW WILL MOVE INTO SBN. LESS CONFIDENT IN THEM REACHING FWA BY THE END OF THE TAF PERIOD SO HAVE INCLUDED THE MVFR POSSIBILITY AS A PROB30 AT THIS TIME. THE SOUTHWESTERLY WINDS THIS EVENING WILL BECOME SOUTHERLY AND STRENGTHEN TO 10-15KTS OVERNIGHT AND THEN TO 18G26KTS DURING THE MORNING ON SATURDAY. WINDS WILL BECOME MORE SOUTH SOUTHWESTERLY AND MAY SUBSIDE A LITTLE TOWARDS THE END OF THE TAF PERIOD BUT ARE LIKELY TO REMAIN AROUND 15KTS. PREV DISCUSSION... /ISSUED 336 PM EST FRI JAN 16 2009/ SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT MAIN FOCUS IN THE SHORT TERM IS TEMPS/WIND CHILLS TONIGHT AND SN/FZDZ CHANCES SAT INTO SAT NIGHT. WINDS DROPPING TO NEAR 5 KNOTS AND MAINLY CLEAR SKIES EARLY THIS EVENING WILL PROBABLY ALLOW TEMPS TO PLUMMET BACK TOWARDS -10F THIS EVENING. EXPECT SOME WARMING AFTER MIDNIGHT AS SOUTHWESTERLY LL FLOW DEVELOPS ON BACKSIDE OF 1040MB ARCTIC HIGH WHICH WILL SHIFT EASTWARD INTO THE CENTRAL APPS/MIDDLE ATLANTIC. THEREFORE...HAVE NON DIURNAL TEMPS TONIGHT WITH VALUES HOPEFULLY WARMING INTO THE SINGLE DIGITS ABV ZERO BY 12Z SAT. COLD TEMPS COMBINED WITH LIGHT SSW SFC WINDS WILL KEEP APPARENT TEMPS IN THE -15 TO -25F RANGE...SO WENT WITH A WIND CHILL ADVISORY FOR THE ENTIRE CWA THROUGH 09Z SATURDAY. SHORTWAVE CURRENTLY OVER NRN FRINGE OF HIGHLY AMPLIFIED EASTERN PAC/WESTERN NOAM RIDGE WILL RAPIDLY SLIDE SEWD INTO THE UPPER MIDWEST LATE TONIGHT...AND THE GREAT LAKES SATURDAY INTO SATURDAY NIGHT. FAVOR FARTHER NORTH AND DRIER NAM/SREF/ECMWF SOLUTIONS OVER THE GFS IN TRACKING ASSOCIATED SFC REFLECTION INTO CENTRAL LOWER MICHIGAN BY SATURDAY EVENING...AS THE NAM HAS PERFORMED BETTER FOR THE LAST SEVERAL CLIPPER EVENTS WHEN COMPARED TO THE GFS. WAA/ISENTROPIC UPGLIDE WITH 40-50KT CROSS ISOBARIC FLOW AND 2-3 G/KG MOISTURE SURGE OVER ARCTIC DOME DOES SUPPORT A BAND OF LIGHT/MODERATE SNOW PIVOTING EAST THROUGH AT LEAST FAR NORTHERN AREAS ON SATURDAY. BETTER CHANCES FOR DECENT SNOW ACCUMULATIONS IN THE 1-3 INCH RANGE APPEAR POSSIBLE IN THE COLDWATER/HILLSDALE AREAS CLOSER TO THE DEEPER MOISTURE AND BETTER DYNAMICS. MAYBE A COATING TO AN INCH IN CENTRAL AREAS WITH LITTLE IF ANY ACCUMULATION IN THE SOUTHWEST. ADDED FREEZING DRIZZLE MENTION TO WESTERN/SOUTHERN AREAS SAT AFTN/EVE AS NAM FCST SOUNDINGS CONSISTENT IN SHOWING LACK OF MOISTURE IN THE ICE PRODUCTION ZONE WITH LL MOISTURE TRAPPED UNDER A LOWERING INVERSION. SLICK SPOTS ON AREA ROADS WILL BE POSSIBLE IF THIS MATERIALIZES. OTHERWISE... IT WILL FEEL BALMY OUT BY TOMORROW AFTERNOON WITH HIGHS RECOVERING ALL THE WAY BACK INTO THE 20S. LARGE SCALE LIFT PER 5-3H Q-VECTOR CONVERGENCE AND DIFF PVA AHEAD OF H5 TROUGH AXIS SHIFTS EAST BY 00Z SUN WITH JUST LINGERING LIGHT SNOW SHOWERS/FLURRIES/PATCHY FZDZ SAT EVE. CAA BEHIND SYSTEM WILL ALLOW FOR LAKE EFFECT SNOW SHOWERS TO DEVELOP ACROSS THE FAR NW LATE SATURDAY NIGHT. CONTINUED WITH LIKELY POPS IN THESE AREAS 06-12Z SUN. DELTA T/S OF 15-18 AND SATURATION WITHIN THE DGZ INDICATE POTENTIAL FOR SOME SNOW ACCUMULATION WITH LAKE EFFECT. HOWEVER...INVERSION NEAR 5KFT AND UNFAVORABLE 280/290 DEGREE FETCH DO NOT FAVOR ACCUMS ABOVE 2 INCHES. LONG TERM... SUNDAY THROUGH FRIDAY... LONG TERM WILL SEE CHANGES TO LARGE SCALE UPPER AIR PATTERN OVER THE CONUS AS WESTERN RIDGE BEGINS TO BREAK DOWN AS STRONG PACIFIC ENERGY UNDERCUTS IT. TROUGHINESS OVER THE EASTERN CONUS EXPECTED TO PERSIST AS NORTHERN BRANCH OF UPPER JET REMAINS DOMINANT AND CONTINUES TO DIVE INTO THE GREAT LAKES. ECMWF AND GFS HAVE SIGNIFICANTLY DIFFERENT SOLUTIONS IN HOW THIS PATTERN WILL EVOLVE AND THEREFORE A LARGE DEGREE OF UNCERTAINTY IN THE LATTER PART OF THE LONG TERM GRIDS. BEGINNING OF PERIOD WILL SEE CLIPPER SYSTEM CROSSING AND EXITING THE AREA WITH CHANCES FOR LIGHT SNOW SUNDAY. LAKE EFFECT POTENTIAL CONTINUES BEHIND CLIPPER SUNDAY AFTERNOON AND SUNDAY NIGHT...INTO MONDAY MORNING. THIS IS AN INTERESTING SETUP AND HAS POTENTIAL FOR A DECENT SNOW EVENT ASSUMING MOISTURE REMAINS IN PLACE. LIMITING FACTOR WILL BE TRANSITORY NATURE OF BAND AND DEPTH OF MOISTURE. DUE TO LIMITING FACTORS AND QUESTIONS ON BAND PLACEMENT HAVE CONTINUED WITH HIGH CHANCE POPS RATHER THAN LIKELY OR CATEGORICAL. LATEST NAM INDICATING EVOLUTION INTO SINGLE BAND INTO FAR WESTERN COUNTIES BY MONDAY MORNING. NAM HAS ALSO STRUGGLED WITH RECENT LAKE EVENTS IN THESE PERIODS SO STILL SOME DOUBT. STAYED CLOSE TO A BLEND OF PREVIOUS GRIDS AND HPC FOR MIDDLE TO LATE PART OF LONG TERM GIVEN MODEL DIFFERENCES. ECMWF HAS BEEN MODEL OF CHOICE MOST OF WINTER AND IT IS NOT AS AGGRESSIVE WITH MID WEEK WARM UP AS GFS...WHICH SHOWS 850MB TEMPS WELL ABOVE CLIMO FOR MID JANUARY. HAVE DOUBTS AT THIS TIME ON SUCH A PRONOUNCED WARM UP GIVEN STRONG ARCTIC AIR MASS IN PLACE AND DEEP SNOW PACK THAT EXISTS. PREFER COOLER ECMWF. GRIDS AND HPC IN THE MIDDLE AND PREFER TO KEEP IT THAT WAY UNTIL CLEAR PATTERN EVOLVES. ECMWF SHOWING ANOTHER COLD ARCTIC FRONT LATE IN THE PERIOD. GFS DEVELOPING A RATHER STRONG CYCLONE BY DAY 7. AGAIN WILL STAY IN MIDDLE GROUND AND SIDE WITH HPC FOR COLLABORATION GIVEN WIDE VARIETY OF POSSIBLE SOLUTIONS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL ADVISORY UNTIL 7 AM EST /6 AM CST/ SATURDAY FOR INZ003>009-012>018-020-022>027-032>034. MI...WIND CHILL ADVISORY UNTIL 7 AM EST SATURDAY FOR MIZ077>081. OH...WIND CHILL ADVISORY UNTIL 7 AM EST SATURDAY FOR OHZ001-002-004- 005-015-016-024-025. LM...NONE. && $$ SHORT TERM...STEINWEDEL LONG TERM...LASHLEY AVIATION...ARNOTT UPDATE...ARNOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 100 AM EST THU JAN 15 2009 .AVIATION... MINOR TWEAKS TO KSBN TAF WRT TIMING OF INTENSE LES BAND NOW POINTED FM BRIDGEMAN TOWARD KSBN. LIFR VSBYS AS 30 DBZ REFLECTIVITY IMPINGES UPON AIRFIELD FOR NEXT TWO HOURS. MUCH LESS INTENSITY AS BAND STRUGGLES TO OVERCOME DRY ENVIRONMENTAL AIR AS IT REACHES KFWA...THOUGH BRIEF PD OF IFR VSBYS REMAIN PROBABLE AT TIMES...WITH KASW EVEN DOWN AS LOW AS 1/2SM PAST HOUR. AS TEMPS CONT TO FALL SOME CONCERN WRT PTCHY FREEZING FOG DVLPG...FOR NOW HAVE LEFT OUT AS LOW PROBABILITY AND CONT TO MONITOR. && .PREV DISCUSSION... AVIATION/UPDATE... INTENSE LK EFFECT SNOW BAND HAS STRUGGLED THIS EVENING DUE TO A MYRIAD OF EMBEDDED MESOLOWS DISRUPTING LL FLW AND FAILURE OF BAND HOLDING IN ANY ONE SPOT FOR ANY SIG LENGTH OF TIME. HWVR OBSVD SNOW INTENSITIES POINT TO 1 TO 2 INCH PER HOUR RATES AND BAND REORGANIZING NORTH OF KBEH TO KMKG AND WHICH WILL BECOME THE DOMINANT PLAYER THROUGH THU MORNING. OF NOTE HWVR ARE STG GRADIENT WINDS UPSTREAM OF INTENSE LK BAND WHICH WILL SWING EWD BEHIND THIS FTR OVERNIGHT AND THU MORNING AND WHICH WILL LEAD TO AREAS OF BLSN AND EXTREME WIND CHILLS AS TEMPS DROP BACK BELOW ZERO WEST OF LK CLOUD BAND. SMALL ADJUSTMENTS MADE TO ACCOUNT FOR OBSVD TRENDS THIS EVE. VFR CONDS AT THE TERMINALS WILL DETERIORATE AS LK BAND SHIFT EWD...ESP AT KSBN W/PD OF LIFR LIKELY IN +SN. MORE QUESTIONABLE TO KFWA AND WHETHER OR NOT BAND WILL EXTEND THAT FAR INLAND BUT CERTAINLY PSBL GIVEN UPSTREAM FLW VECTORS AND TIGHTLY FOCUSED BNDRY LYR CONVERGENCE. SHORT TERM... TONIGHT THROUGH THURS NIGHT WEAK CLIPPER SYSTEM CENTERED OVER CENTRAL IN...IS CONTINUING TO EXIT THE REGION. SNOW IS STARTING TO WIND DOWN ACROSS THE REGION AS THE STRONGEST UPGLIDE AND LARGE SCALE ASCENT IS SHIFTING EAST INTO OH. THIS WILL CONTINUE TO BE THE TREND THROUGH THE AFTERNOON AND INTO THE EVENING. WILL LET THE ADV EXPIRE AT 4 PM WESTERN PORTION /7PM EASTERN PORTION AS THE SNOW INTENSITY WILL CONTINUE TO WANE ACROSS THE REGION...WITH THE WORST BEING OVER. FARTHER UPSTREAM...MASSIVE HIGH PRESSURE CONTINUES TO SLIDE DOWN INTO THE NORTHERN CONUS...WITH A CENTER CURRENTLY INDICATED AT AN IMPRESSIVE 1046MB. STRONG CAA COUPLED WITH BACKING LL FLOW...AND DELTA T/S APPROACHING 23 C...WILL SUPPORT THE DEVELOPMENT OF LAKE SNOWS...WITH A PERIOD OF INTENSE SNOWFALL LIKELY ACROSS PORTIONS OF THE REGION. IN ADDITION...VERY COLD ARCTIC...WITH APPROX -22C AT H925 AT 00Z FRI COUPLED WITH WINDS OF 10 TO 15 MPH WILL SUPPORT DANGEROUSLY COLD WIND CHILLS...WITH READINGS DOWN TO -30F AT TIMES. PERIOD WILL FEATURE SFC RIDGING AS THE CLIPPER SYSTEM PUSHES OUT OF THE AREA. MORE IMPORTANTLY...FAVORED NORTHERLY FLOW WILL SUPPORT AN INTENSE PERIOD OF LAKE SNOWS...ALLOWING SOME HIGH ACCUMS IN THE NORTHWEST. GIVEN THE NATURE OF THE FORECAST CONCERN BEING LAKE EFFECT PROCESSES...HAVE TRIED TO UTILIZED THE NAM/RUC WHERE POSSIBLE MESOSCALE EFFECTS ARE MORE EASILY VIEWABLE. THE CAVEAT TO THIS SITUATION IS THAT THE EXTREME INSTABILITY PRESENT WILL HIGHLY FAVOR THERMODYNAMICAL ORGANIZATION OF THE LAKE SNOW EVENT...AS OPPOSED TO SHEAR. THIS IS EVEN MORE TRUE SINCE THE FLOW IS NOW INDICATED TO BE WEAKER THAN PROGS JUST 2 DAYS AGO INDICATED. BOTTOM LINE...TRYING TO PINPOINT THE LOCATION OF THE HEAVIEST SNOW WILL BE VERY DIFFICULT...AS ONE OR TWO MESO-LOWS WOULD CERTAINLY DISRUPT THE FLOW...SHIFTING THINGS EAST OR WEST. HAVE STAYED VERY CLOSE TO NAM 12 PROGS AS THEY HAVE BEEN VERY HELPFUL WRT LAKE EFFECT EVENTS THIS YEAR..OPTING TO BLEND IN QPF AREAL AMOUNTS FROM THE GFS AND RUC FOR UNCERTAINTY PURPOSES. TONIGHT...LAKE BANDING IS ALREADY IN PROGRESS ACROSS WESTERN PORTIONS OF MI...EXTENDING SOUTH INTO GYY. LL FLOW WILL BACK NORTHERLY AND ALLOW A PERIOD OF LONGER FETCH ENHANCEMENT. STRONG CAA WITH DELTA T/S APPROACHING 23C WILL SUPPORT EXTREME INSTABILITY WITH H925 OMEGA PROGGED AOA 27 MICROBARS/SEC. LAKE INDUCED EQUILIBRIUM LEVELS PROGGED AT 12KFT WITH A LARGE PORTION OF UPWARD MOTION IN THE DGZ WOULD LIKELY SUPPORT SNOWFALL RATES AT IMPRESSIVE VALUES OF 2 POSSIBLY 3 INCHES PER HOUR. CURRENT INDICATIONS SUPPORT THE HEAVIEST SNOW ACROSS PORTIONS OF LA PORTE AND BERRIEN COUNTIES...AND POSSIBLY WESTERN CASS. STRONGEST INTENSITY LOOKS TO FAVOR LA PORTE AND POSSIBLY ST. JOE COUNTY IN...BUT THE BAND IS EXPECTED TO BE TRANSIENT AS IT PUSHES INTO ST JOE COUNTY IN. SOUTHWEST MI COUNTIES WILL SEE A PERIOD OF INTENSE SNOW. HOWEVER...VERY DRY AIR UPSTREAM /DOWN 20 PERCENT AT H85/ COMBINED WITH FALLING INVERSION HEIGHTS WILL TEND TO TRANSITION BANDS TO MULTIPLE SHORE PARALLEL ORGANIZATION...BUT A LONG DURATION OF SNOWFALL WILL FAVOR HIGH AMOUNTS. HAVE OPTED FOR AMOUNTS TO 12 INCHES IN BERRIEN COUNTY WHERE DURATION WILL BE MAXIMIZED. HIGH AMOUNTS WILL BE POSSIBLE IN LA PORTE...BUT UNCERTAINTY REMAINS ON HOW LONG THE BAND WILL SETUP OVER THE AREA...PRECLUDES HIGH AMOUNT MENTION AT THIS TIME. LAKE SNOWS WILL SHIFT NORTH INTO MI BY THU AFTERNOON...WITH LIGHT TO MODERATE SNOWS CONTINUING OVER SOUTHWEST MI. THE OTHER ISSUE WILL BE STRONG WINDS ON THE BACKSIDE OF ANY LONG FETCH BANDS THAT DEVELOP IN REPONSE TO MOMENTUM ADJUSTMENT PER CONVECTIVE INFLUENCES. DEEP MIXING AND ENHANCED FLOW COULD SUPPORT 20 TO 30 MPH WINDS OVER PORTIONS OF BERRIEN AND LA PORTE COUNTY WITH HIGHER GUSTS. ESPECIALLY GIVEN 30 KNOTS PROGGED AT H925 BEING ABLE TO TRANSLATE DOWN. HAVE STARTED THE WIND CHILL ADV LATER GIVEN FORECAST TEMPS/TD/WINDS...AND ALLOWED THE WARNING TO LAST INTO FRI WHERE THE DATABASE INDICATES APPARENT T/S IN THE 25 TO 30 BELOW RANGE. HAVE CONTINUED TO TREND THU HIGHS AND LOWS DOWN GIVEN MOS TRENDS...TEMP/RH PROFILES ALOFT/AND MODEL 2M TEMPS. TEMPS AOA -20F WILL BE POSSIBLE AT SOME LOCATIONS WHERE CLEARING AND CALM WINDS WILL OVERLAP. TEMPS ARE LIKELY TO REMAIN BELOW ZERO AT MANY LOCATIONS ON THU. LONG TERM... FRI THROUGH WED STRONGLY POSITIVE PNA PATTERN WILL BEGIN THE PERIOD WITH LARGE TROUGH IN THE EAST WELL ESTABLISHED. THIS PATTERN WILL PERSIST INTO EARLY NEXT WEEK BEFORE THE EASTERN PACIFIC RIDGE BEGINS TO FLATTEN AND PULL EAST BRINGING A SLOW MODERATING TREND TO OUR AREA. GFS/GEFS/CMC/ECMWF ARE IN PRETTY GOOD AGREEMENT ON THIS OVERALL EVOLUTION...WITH THE PRIMARY DIFFERENCES BEING ON THE HANDLING OF A SERIES OF SHORTWAVES THAT WILL DROP THROUGH THE AREA DURING THE PERIOD IN THE DEEP LAYER NORTHWESTERLY FLOW. LAKE EFFECT SNOW WILL BE ONGOING TO START THE PERIOD WITH T850 AROUND -20C AND CONTINUED WESTERLY FLOW. HAVE KEPT CHC POPS FOR SHSN OVER SOUTHERN MI AND THE NORTHERNMOST ROW OF COUNTIES IN IN. THIS LINES UP A LITTLE BETTER WITH H925 AND H850 WINDS VS MODEL QPF FIELDS. T925 WOULD SUGGEST HIGHS IN THE LOWER SINGLE DIGITS AND WILL CONTINUE TO UNDERCUT THESE A LITTLE GIVEN SUCH COLD OVERNIGHT LOWS. ANOTHER BRIEF BREAK OCCURS FRIDAY EVENING BEFORE MID AND HIGHS CLOUDS ROLL BACK IN WITH SN LIKELY ARRIVING AFTER MIDNIGHT AHEAD OF THE NEXT CLIPPER. HAVE GONE WITH NON DIURNAL TEMPERATURE TRENDS FRIDAY NIGHT GIVEN THE INCREASING CLOUD COVER...BUT MOST SITES WILL SEE LATE EVENING LOWS AGAIN BELOW ZERO. CLIPPER FOR SATURDAY LOOKS LIKE A WIDESPREAD LIGHT SNOWFALL WITH A LOW TRACK SOMEWHERE NEAR OVERHEAD AND A LOW TRACK TO THE SOUTHEAST SUGGESTING THE MOST SNOW OVER NORTHEASTERN AREAS TAPERING OFF TO THE SOUTH AND WEST. TEMPERATURES WILL RISE THROUGH THE EVENT INTO THE LOWER 20S. FOR SUNDAY DETAILS BECOME A LITTLE LESS CLEAR AS THE GFS SHOWS ANOTHER WAVE DROPPING SOUTH IN THE NORTHWEST FLOW WITH THE ECMWF/CMC AND QUITE A FEW GEFS MEMBERS VOID OF ANY DISTURBANCES WITH COLD NORTHWEST FLOW SPAWNING LAKE EFFECT SHSN. WILL FOLLOW THIS LATTER CONSENSUS...WHICH WAS WELL CAPTURED IN THE PREVIOUS SET OF GRIDS AND RESTRICT CHC POPS TO THE NORTHEASTERN 2/3RDS OF THE CWA. HIGHS SHOULD REACH THE LOWER 20S. FOR THE MONDAY THROUGH WEDNESDAY TIMEFRAME...THE CONTINUED COLD NORTHWESTERLY FLOW WILL GRADUALLY GIVE WAY TO INCREASING TEMPS ALOFT AS THE WESTERN RIDGE BEGINS TO NUDGE TOWARDS THE AREA. LAST WAVE IN THE NORTHWEST FLOW COULD BRING SOME LIGHT SNOW ON MONDAY WITH DRY WEATHER BECOMING MORE LIKELY FOR TUESDAY AND WEDNESDAY AS TEMPS ALOFT WILL WARM TO THE POINT WHERE ANY LAKE RESPONSE SHOULD FINALLY BE OVER. TEMPERATURES WILL WARM INTO THE MID 20S FOR TUESDAY AND THEN INTO THE LOWER 30S BY WEDNESDAY. WARMER TEMPS AT THIS RANGE ARE POSSIBLE AS TEMPS ALOFT SHOULD WARM PRETTY QUICKLY WITH THE RIDGE ARRIVAL...BUT AT THIS RANGE...HAVE TO GIVE SOME CREDENCE TO CLIMATOLOGY. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR INZ018- 026-027-033-034. WIND CHILL WARNING FROM MIDNIGHT EST /11 PM CST/ TONIGHT TO 12 PM EST /11 AM CST/ FRIDAY FOR INZ003>009-012>018-020- 022>027-032>034. LAKE EFFECT SNOW WARNING UNTIL 6 AM CST THURSDAY FOR INZ003-012. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THURSDAY FOR INZ004-005- 014. WINTER WEATHER ADVISORY UNTIL 5 PM EST /4 PM CST/ THIS AFTERNOON FOR INZ012>017-020-022>025-032. MI...WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 12 PM EST FRIDAY FOR MIZ077>081. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THURSDAY FOR MIZ077. LAKE EFFECT SNOW WARNING FROM 10 PM THIS EVENING TO 7 PM EST THURSDAY FOR MIZ078-079. OH...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ015- 016-024-025. WIND CHILL WARNING FROM MIDNIGHT TONIGHT TO 12 PM EST FRIDAY FOR OHZ001-002-004-005-015-016-024-025. LM...HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THURSDAY FOR LMZ043- 046. GALE WARNING UNTIL 7 AM EST THURSDAY FOR LMZ043-046. && $$ SHORT TERM...JC LONG TERM...ARNOTT AVIATION/UPDATE...HOLSTEN AVIATION...MURPHY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1232 PM EST THU JAN 15 2009 .SHORT TERM.../THE REST OF TODAY/ THE MAIN UPDATE TO THE FORECAST WAS TO PROLONG SNOW SHOWER ACTIVITY A LITTLE. LATEST RUC RH FIELDS MATCH UP WELL WITH CURRENT CLOUD COVER. RUC SHOWS THE MOISTURE LINGERING A LITTLE LONGER INTO THE AFTERNOON...ESPECIALLY IN THE EAST. LAPSE RATES INCREASE LATE THIS MORNING INTO THE AFTERNOON...AND WITH SOME BROAD TROUGHING AT H5...THIS MAY HELP KEEP AT LEAST SOME FLURRIES OR LIGHT SNOW SHOWERS IN THE AREA. THE MOISTURE LAYER IS RATHER SHALLOW...AND THERE IS AN INVERSION AROUND 5 KFT...WHICH WILL HELP LIMIT ACCUMULATIONS... ALTHOUGH THERE COULD BE AN ISOLATED LOCATION WITH UP TO A HALF INCH OF DRY SNOW IN THE HIGHER TERRAIN. ANY ONGOING FLURRIES WILL BE ENDING BY LATE AFTERNOON. WITH H8 TEMPS WILL BE DROPPING OFF A LITTLE DURING THE DAY...REACHING -21 DEG C LATER ON IN THE AFTERNOON. NOT EXPECTING MUCH TEMPERATURE RECOVERY TODAY...AND TWEAKED TEMPS DOWN A LITTLE IN THE GRIDS...ALTHOUGH THIS DID NOT CHANGE THE TEXT FORECAST WORDING MUCH. WIND CHILLS TODAY WILL RANGE FROM FIVE BELOW IN THE NORTH...WITH ZERO TO 10 ABOVE ELSEWHERE. UPDATED FORECAST PRODUCTS HAVE BEEN SENT. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /THE REST OF TODAY/ ISSUED AN UPDATE TO REMOVE THE EARLY THIS MORNING PERIOD AND CONTINUE THE CHANCE OF FLURRIES AND ISOLATED TO SCATTERED SNOW SHOWERS A COUPLE HOURS LONGER THAN PREVIOUS FORECAST...BASED ON RADAR TRENDS. OTHERWISE...NO CHANGES. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TODAY THROUGH SATURDAY/ A CLIPPER SYSTEM AND ASSOCIATED SHORTWAVE HAVE HELPED TO REINFORCE THE MEAN EASTERN CONUS AND EASTERN NOAM TROUGH. THE AXIS OF THIS MEAN THROUGH WILL SHIFT EAST WITH TIME THROUGH THE PERIOD...WITH HEIGHT RISES BEGINNING TONIGHT AND CONTINUING INTO SATURDAY. AT THE SFC...ARCTIC HIGH PRESSURE WILL BUILD TOWARD THE REGION FROM THE NORTHERN PLAINS TODAY AND TONIGHT...BEFORE PASSING ACROSS THE AREA ON FRIDAY AND FRIDAY NIGHT. THE NEXT IN A SERIES OF CLIPPER SYSTEMS WILL APPROACH THE AREA ON SATURDAY AS THE HIGH REACHES THE MID ATLANTIC AND NORTHEASTERN US. NW TO WNW UPSLOPE FLOW WILL HOLD IN THE STRATOCU INTO THIS MORNING ALONG WITH SOME SNOW SHOWERS AND FLURRIES. DEWPOINTS UPSTREAM DROP INTO THE SINGLE DIGITS AND BELOW...SO AVAILABLE MOISTURE IS MEAGER. HOWEVER...WITH TEMPS CONTINUING TO FALL...MOST OF WHAT FALLS WILL ACCUMULATE AND HAVE A VERY HIGH SNOW TO LIQUID RATIO. AN ADDITIONAL DUSTING TO MAYBE A QUARTER OF AN INCH CANNOT BE RULED OUT BY DAWN... BUT WE WILL BE HARD PRESSED TO GET 0.01 INCHES OF LIQUID...ESPECIALLY AFTER 12Z...AND GIVEN RECENT OBS AT JKL...OF VIS MOSTLY 6 SM OR BETTER MOST OF THIS SHOULD BE NOTHING MORE THAN FLURRIES...THOUGH COLD ADVECTION WILL LEAD TO RATHER STEEP LAPSE RATES AND THE RISK OF FLURRIES LINGERING INTO THE MORNING...IF NOT MIDDAY IN THE FAR SE. WILL COVER THIS WILL FLURRIES AND LOW CHANCE POPS NEAR THE VA BORDER. OTHERWISE...850 MB TEMPS SHOULD PLUMMET TO NEAR 20C THIS AFTERNOON IF NOT LOWER IN NE KY...SO DESPITE SOME LIMITED SUNSHINE FROM TIME TO TIME BY THIS AFTERNOON...TEMPS WILL RISE MINIMALLY TODAY. THE HIGH WILL CONTINUE TO BUILD INTO THE REGION AND WITH CLEARING SKIES...TEMPS SHOULD PLUMMET...THOUGH A RATHER TIGHT PRESS GRADIENT FOR THE FIRST PART OF THE NIGHT SHOULD KEEP TEMPS FROM FALLING TO THE DEWPOINTS...ESPECIALLY EASTERN AND SE PART OF THE CWA. MAV AND MOS GUIDANCE SUGGESTS LOWS IN THE SINGLE DIGITS IN MOST AREAS...AND EVEN SOME READINGS A COUPLE OF DEGREES BELOW ZERO IN THE NW. OTHER THAN A FEW HIGH CLOUDS IN THE AFTERNOON...FRI SHOULD AVERAGE MOSTLY SUNNY...BUT WITH COLD AIRMASS STILL ENTRENCHED AS THE STRONG HIGH SETTLES INTO THE OH VALLEY...TEMPS WILL STRUGGLE TO REACH 20 IN ALL BUT SOME OF THE DEEPER VALLEYS AND THE SW CWA. WITH THE HIGH GRADUALLY SHIFTING EAST OF THE AREA ON FRI NIGHT AND THE LOW LEVEL FLOW GRADUALLY BECOMING SOUTHERLY...A RIDGE/VALLEY TEMP SPLIT CONTINUES TO APPEAR LIKELY. DEWPOINTS BY THAT POINT SHOULD BE NEAR ZERO IF NOT A COUPLE OF DEGREES IN MOST AREAS. MANY OF THE VALLEY LOCATIONS WILL BE A BIT COOLER ON FRI NIGHT THAN TONIGHT AND IF THE INCREASING HIGH CLOUDS AHEAD OF THE NEXT CLIPPER REMAIN THIN...SOME OF THE COLDER SPOTS DROPPING BELOW ZERO CANNOT BE RULED OUT. ATTM...KEPT THE NORMALLY COOLER VALLEYS IN THE 0 TO 5 ABOVE RANGE...BUT OVERALL CUT MIN T FOR FRI NIGHT A COUPLE OF DEGREES FROM THE PREVIOUS FORECAST IN ALL AREAS. SOUTHERLY WINDS...PERHAPS A BIT GUSTY BETWEEN THE HIGH AND THE APPROACHING CLIPPER WILL LEAD TO A MODERATION IN THE AIRMASS ON SAT...WITH 8H TEMPS RISING ABOVE -10C. EVEN STILL...MAX TEMPS SHOULD AVERAGE BELOW NORMAL IN THE LOW TO MID 30S. WITH CLOUDS CONTINUING TO INCREASE AHEAD OF THE NEXT SYSTEM. PRECIP CHANCES WILL HOLD OFF UNTIL THE EXTENDED TIME FRAME. .LONG TERM.../SATURDAY NIGHT THROUGH WEDNESDAY/ UPPER LEVEL TROUGH WILL REMAIN ACROSS THE EASTERN CONUS THROUGH EARLY NEXT WEEK BUT THE AXIS WILL BE SHIFTING EASTWARD WITH TIME AND BY WEDNESDAY... PROGS INDICATE THE TROUGH SHOULD SHIFT OFF THE ATLANTIC COAST. ABNORMALLY COLD TEMPERATURES WILL PERSIST FOR MUCH OF THE PERIOD BUT THE TRULY ARCTIC AIRMASS OVERHEAD NOW WILL MODERATE. SPOKES OF ENERGY DROPPING INTO THE BASE OF THE TROUGH WILL CONTINUE TO FUEL PERIODIC CHANCES FOR SNOW SHOWERS THROUGH AT LEAST TUESDAY BEFORE SURFACE HIGH PRESSURE FINALLY BUILDS INTO THE REGION. WHILE MODEL AGREEMENT IN THE OVERALL PATTERN IS FAIRLY GOOD THROUGH THE PERIOD... THERE REMAINS CONSIDERABLE UNCERTAINTY WITH THE TIMING AND INTENSITY OF INDIVIDUAL SHORTWAVES. THEREFORE... FEW CHANGES WERE MADE TO INHERITED FORECAST. SENSIBLE WEATHER SHOULD FEATURE INCREASING CHANCES FOR SNOW SHOWERS LATE SATURDAY NIGHT INTO SUNDAY AS A DIGGING SHORTWAVE SLIDES ACROSS THE UPPER OHIO VALLEY. 15/00Z ECMWF IS MUCH LESS MOIST COMPARED TO THE SAME RUN OF THE GFS AND IS GENERALLY PREFERRED OWING TO THE DRY SOURCE REGION OF THE CLIPPER SYSTEM AND THE FACT THAT THE CORE OF THE SYSTEM TRACKS TO OUR NORTHEAST. A REINFORCING SHOT OF COLD ARRIVES BEHIND THIS SYSTEM BUT NO REAL CHANCE TO CLEAR OUT AS NEXT SYSTEM APPROACHES SO TEMPS SHOULD NOT DROP OFF TOO MUCH. AFTER A BRIEF LULL... ANOTHER SHORTWAVE DROPS SOUTHWARD TOWARD THE REGION LATE ON MONDAY INTO THE DAY ON TUESDAY. 15/00Z GFS/ECMWF/GEM AND ENSEMBLE MEAN ARE ALL FAIRLY BULLISH WITH THIS SYSTEM... ALTHOUGH TIMING DIFFERENCES EXIST. NOT REAL CONFIDENT WITH THE SOLUTIONS OFFERED AT THIS TIME SO WILL KEEP POPS (SNOW SHOWERS) LOW AND AT THIS TIME AND TAPER THEM OFF TUESDAY EVENING. HIGH PRESSURE BUILDING IN AND RISING HEIGHTS SHOULD THEN BRING MORE TRANQUIL AND WARMER CONDITIONS FOR WEDNESDAY... ALTHOUGH NOT QUITE AS WARM AS THE GFSX MOS GUIDANCE SUGGESTS. && .AVIATION.../18Z TO 18Z/...UPDATED SCATTERED SNOW SHOWERS AND FLURRIES CONTINUE ACROSS THE AREA AS LOW LEVEL LAPSE RATES STEEPEN...AND A BROAD UPPER TROF MOVES THROUGH. SEEING MAINLY MVFR CONDITIONS...WITH TEMPO IFR IN BRIEF BURSTS OF HEAVIER SNOW. THE SNOW SHOULD BE WINDING DOWN LATER ON THIS AFTERNOON AS MOISTURE DECREASES...AN INVERSION LOWERS...AND HIGH PRESSURE BUILDS IN. CIGS SHOULD LIFT TO VFR BY 20Z TO 21Z...WITH SKC EXPECTED AFTER SUNSET THROUGH THE END OF THE TAF PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...JP/WJM LONG TERM....ABE AVIATION...WJM ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1052 AM EST THU JAN 15 2009 .SHORT TERM.../THE REST OF TODAY/...UPDATED THE MAIN UPDATE TO THE FORECAST WAS TO PROLONG SNOW SHOWER ACTIVITY A LITTLE. LATEST RUC RH FIELDS MATCH UP WELL WITH CURRENT CLOUD COVER. RUC SHOWS THE MOISTURE LINGERING A LITTLE LONGER INTO THE AFTERNOON...ESPECIALLY IN THE EAST. LAPSE RATES INCREASE LATE THIS MORNING INTO THE AFTERNOON...AND WITH SOME BROAD TROUGHING AT H5...THIS MAY HELP KEEP AT LEAST SOME FLURRIES OR LIGHT SNOW SHOWERS IN THE AREA. THE MOISTURE LAYER IS RATHER SHALLOW...AND THERE IS AN INVERSION AROUND 5 KFT...WHICH WILL HELP LIMIT ACCUMULATIONS... ALTHOUGH THERE COULD BE AN ISOLATED LOCATION WITH UP TO A HALF INCH OF DRY SNOW IN THE HIGHER TERRAIN. ANY ONGOING FLURRIES WILL BE ENDING BY LATE AFTERNOON. WITH H8 TEMPS WILL BE DROPPING OFF A LITTLE DURING THE DAY...REACHING -21 DEG C LATER ON IN THE AFTERNOON. NOT EXPECTING MUCH TEMPERATURE RECOVERY TODAY...AND TWEAKED TEMPS DOWN A LITTLE IN THE GRIDS...ALTHOUGH THIS DID NOT CHANGE THE TEXT FORECAST WORDING MUCH. WIND CHILLS TODAY WILL RANGE FROM FIVE BELOW IN THE NORTH...WITH ZERO TO 10 ABOVE ELSEWHERE. UPDATED FORECAST PRODUCTS HAVE BEEN SENT. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /THE REST OF TODAY/ ISSUED AN UPDATE TO REMOVE THE EARLY THIS MORNING PERIOD AND CONTINUE THE CHANCE OF FLURRIES AND ISOLATED TO SCATTERED SNOW SHOWERS A COUPLE HOURS LONGER THAN PREVIOUS FORECAST...BASED ON RADAR TRENDS. OTHERWISE...NO CHANGES. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TODAY THROUGH SATURDAY/ A CLIPPER SYSTEM AND ASSOCIATED SHORTWAVE HAVE HELPED TO REINFORCE THE MEAN EASTERN CONUS AND EASTERN NOAM TROUGH. THE AXIS OF THIS MEAN THROUGH WILL SHIFT EAST WITH TIME THROUGH THE PERIOD...WITH HEIGHT RISES BEGINNING TONIGHT AND CONTINUING INTO SATURDAY. AT THE SFC...ARCTIC HIGH PRESSURE WILL BUILD TOWARD THE REGION FROM THE NORTHERN PLAINS TODAY AND TONIGHT...BEFORE PASSING ACROSS THE AREA ON FRIDAY AND FRIDAY NIGHT. THE NEXT IN A SERIES OF CLIPPER SYSTEMS WILL APPROACH THE AREA ON SATURDAY AS THE HIGH REACHES THE MID ATLANTIC AND NORTHEASTERN US. NW TO WNW UPSLOPE FLOW WILL HOLD IN THE STRATOCU INTO THIS MORNING ALONG WITH SOME SNOW SHOWERS AND FLURRIES. DEWPOINTS UPSTREAM DROP INTO THE SINGLE DIGITS AND BELOW...SO AVAILABLE MOISTURE IS MEAGER. HOWEVER...WITH TEMPS CONTINUING TO FALL...MOST OF WHAT FALLS WILL ACCUMULATE AND HAVE A VERY HIGH SNOW TO LIQUID RATIO. AN ADDITIONAL DUSTING TO MAYBE A QUARTER OF AN INCH CANNOT BE RULED OUT BY DAWN... BUT WE WILL BE HARD PRESSED TO GET 0.01 INCHES OF LIQUID...ESPECIALLY AFTER 12Z...AND GIVEN RECENT OBS AT JKL...OF VIS MOSTLY 6 SM OR BETTER MOST OF THIS SHOULD BE NOTHING MORE THAN FLURRIES...THOUGH COLD ADVECTION WILL LEAD TO RATHER STEEP LAPSE RATES AND THE RISK OF FLURRIES LINGERING INTO THE MORNING...IF NOT MIDDAY IN THE FAR SE. WILL COVER THIS WILL FLURRIES AND LOW CHANCE POPS NEAR THE VA BORDER. OTHERWISE...850 MB TEMPS SHOULD PLUMMET TO NEAR 20C THIS AFTERNOON IF NOT LOWER IN NE KY...SO DESPITE SOME LIMITED SUNSHINE FROM TIME TO TIME BY THIS AFTERNOON...TEMPS WILL RISE MINIMALLY TODAY. THE HIGH WILL CONTINUE TO BUILD INTO THE REGION AND WITH CLEARING SKIES...TEMPS SHOULD PLUMMET...THOUGH A RATHER TIGHT PRESS GRADIENT FOR THE FIRST PART OF THE NIGHT SHOULD KEEP TEMPS FROM FALLING TO THE DEWPOINTS...ESPECIALLY EASTERN AND SE PART OF THE CWA. MAV AND MOS GUIDANCE SUGGESTS LOWS IN THE SINGLE DIGITS IN MOST AREAS...AND EVEN SOME READINGS A COUPLE OF DEGREES BELOW ZERO IN THE NW. OTHER THAN A FEW HIGH CLOUDS IN THE AFTERNOON...FRI SHOULD AVERAGE MOSTLY SUNNY...BUT WITH COLD AIRMASS STILL ENTRENCHED AS THE STRONG HIGH SETTLES INTO THE OH VALLEY...TEMPS WILL STRUGGLE TO REACH 20 IN ALL BUT SOME OF THE DEEPER VALLEYS AND THE SW CWA. WITH THE HIGH GRADUALLY SHIFTING EAST OF THE AREA ON FRI NIGHT AND THE LOW LEVEL FLOW GRADUALLY BECOMING SOUTHERLY...A RIDGE/VALLEY TEMP SPLIT CONTINUES TO APPEAR LIKELY. DEWPOINTS BY THAT POINT SHOULD BE NEAR ZERO IF NOT A COUPLE OF DEGREES IN MOST AREAS. MANY OF THE VALLEY LOCATIONS WILL BE A BIT COOLER ON FRI NIGHT THAN TONIGHT AND IF THE INCREASING HIGH CLOUDS AHEAD OF THE NEXT CLIPPER REMAIN THIN...SOME OF THE COLDER SPOTS DROPPING BELOW ZERO CANNOT BE RULED OUT. ATTM...KEPT THE NORMALLY COOLER VALLEYS IN THE 0 TO 5 ABOVE RANGE...BUT OVERALL CUT MIN T FOR FRI NIGHT A COUPLE OF DEGREES FROM THE PREVIOUS FORECAST IN ALL AREAS. SOUTHERLY WINDS...PERHAPS A BIT GUSTY BETWEEN THE HIGH AND THE APPROACHING CLIPPER WILL LEAD TO A MODERATION IN THE AIRMASS ON SAT...WITH 8H TEMPS RISING ABOVE -10C. EVEN STILL...MAX TEMPS SHOULD AVERAGE BELOW NORMAL IN THE LOW TO MID 30S. WITH CLOUDS CONTINUING TO INCREASE AHEAD OF THE NEXT SYSTEM. PRECIP CHANCES WILL HOLD OFF UNTIL THE EXTENDED TIME FRAME. .LONG TERM.../SATURDAY NIGHT THROUGH WEDNESDAY/ UPPER LEVEL TROUGH WILL REMAIN ACROSS THE EASTERN CONUS THROUGH EARLY NEXT WEEK BUT THE AXIS WILL BE SHIFTING EASTWARD WITH TIME AND BY WEDNESDAY... PROGS INDICATE THE TROUGH SHOULD SHIFT OFF THE ATLANTIC COAST. ABNORMALLY COLD TEMPERATURES WILL PERSIST FOR MUCH OF THE PERIOD BUT THE TRULY ARCTIC AIRMASS OVERHEAD NOW WILL MODERATE. SPOKES OF ENERGY DROPPING INTO THE BASE OF THE TROUGH WILL CONTINUE TO FUEL PERIODIC CHANCES FOR SNOW SHOWERS THROUGH AT LEAST TUESDAY BEFORE SURFACE HIGH PRESSURE FINALLY BUILDS INTO THE REGION. WHILE MODEL AGREEMENT IN THE OVERALL PATTERN IS FAIRLY GOOD THROUGH THE PERIOD... THERE REMAINS CONSIDERABLE UNCERTAINTY WITH THE TIMING AND INTENSITY OF INDIVIDUAL SHORTWAVES. THEREFORE... FEW CHANGES WERE MADE TO INHERITED FORECAST. SENSIBLE WEATHER SHOULD FEATURE INCREASING CHANCES FOR SNOW SHOWERS LATE SATURDAY NIGHT INTO SUNDAY AS A DIGGING SHORTWAVE SLIDES ACROSS THE UPPER OHIO VALLEY. 15/00Z ECMWF IS MUCH LESS MOIST COMPARED TO THE SAME RUN OF THE GFS AND IS GENERALLY PREFERRED OWING TO THE DRY SOURCE REGION OF THE CLIPPER SYSTEM AND THE FACT THAT THE CORE OF THE SYSTEM TRACKS TO OUR NORTHEAST. A REINFORCING SHOT OF COLD ARRIVES BEHIND THIS SYSTEM BUT NO REAL CHANCE TO CLEAR OUT AS NEXT SYSTEM APPROACHES SO TEMPS SHOULD NOT DROP OFF TOO MUCH. AFTER A BRIEF LULL... ANOTHER SHORTWAVE DROPS SOUTHWARD TOWARD THE REGION LATE ON MONDAY INTO THE DAY ON TUESDAY. 15/00Z GFS/ECMWF/GEM AND ENSEMBLE MEAN ARE ALL FAIRLY BULLISH WITH THIS SYSTEM... ALTHOUGH TIMING DIFFERENCES EXIST. NOT REAL CONFIDENT WITH THE SOLUTIONS OFFERED AT THIS TIME SO WILL KEEP POPS (SNOW SHOWERS) LOW AND AT THIS TIME AND TAPER THEM OFF TUESDAY EVENING. HIGH PRESSURE BUILDING IN AND RISING HEIGHTS SHOULD THEN BRING MORE TRANQUIL AND WARMER CONDITIONS FOR WEDNESDAY... ALTHOUGH NOT QUITE AS WARM AS THE GFSX MOS GUIDANCE SUGGESTS. && .AVIATION.../12Z TO 12Z/ MVFR CIGS AND SOME FLURRIES AND SNOW SHOWERS IN UPSLOPE FLOW BEHIND AN ARCTIC COLD FRONT ARE EXPECTED TO CONTINUE EARLY IN THE PERIOD...BUT SHOULD DISSIPATE BY 15Z. AS THE LOWER ATMOSPHERE CONTINUES TO DRY...CIGS SHOULD RISE INTO THE VFR RANGE IN ALL AREAS DURING BETWEEN 13Z AND 16Z. SKIES WILL THEN SCATTER OUT AND GO CLEAR BETWEEN 16Z AND 0Z...AS HIGH PRESSURE BUILDS INTO THE AREA. WINDS WILL REMAIN WEST TO NORTHWEST AT NEAR 10 KT THROUGH THE DAY THURSDAY...WITH SOME GUSTS IN THE 15 TO 20KT RANGE POSSIBLE. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...JP/WJM LONG TERM....ABE AVIATION...JP ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1048 PM EST THU JAN 15 2009 .SYNOPSIS... ARCTIC HIGH PRESSURE AND VERY COLD AIR WILL BUILD ACROSS THE MID ATLANTIC REGION TONIGHT INTO SATURDAY. A CLIPPER SYSTEM WILL APPROACH FROM THE NORTHWEST SATURDAY NIGHT...THEN GRADUALLY TRACK ACROSS THE MID ATLANTIC REGION SUNDAY AND SUNDAY NIGHT. HIGH PRESSURE BUILDS BACK INTO THE AREA MONDAY...WHILE ANOTHER WEAK LOW PRESSURE SYSTEM APPROACHES THE MID ATLANTIC REGION ON TUESDAY. && .NEAR TERM /THROUGH FRIDAY/... VERY COLD TEMPERATURES IN STORE FOR THE REGION OVERNIGHT. SFC WINDS HAVE SUBSIDED OVER INLAND AREAS AND ARE EXPECTED TO SLOWLY INCREASE AS THE NIGHT PROGRESSES. TEMPS A SHADE COOLER THAN FCSTD SO HAVE OPTD TO LOWER MINS BY 2-4 DEGREES OVER INLAND AREAS. THEREFORE HAVE ADDED ALL OF VA PIEDMONT ZONES TO THE WIND CHILL ADV. NC ZONES LOOK TO REMAIN ABV CRITERIA (0 DEGREES) BUT WOULD NOT BE SURPRISED TO SEE SECTIONS OF NORTHAMPTON/HERTFORD COUNTIES COMING CLOSE. EXPECT A TRANSITION OF DIURNAL-BASED STRATO-CU BANDS OVER BOTH LAND AND WATER TO NW-SE ORIENTED BAY/OCEAN EFFECT PLUMES DOWNWIND OF CHES BAY/ATLC WATER FETCH. OMEGA IS NOT THAT STRONG AT H92 PER THE NAM...ON THE OTHER HAND THE RUC SEEMS TO HAVE A STRONGER OMEGA FIELD PRESENT. SO HAVE SIDED WITH RUC SOLN. ANY LAND AREAS EFFECTED BY ANY SMALL BANDING WOULD MOST LIKELY BE THE LWR VA ERN SHORE (I.E. DOWNWIND FROM CHES BAY WITH THE NNW FLOW IN THE CONVECTIVE BNDRY OR MIXED LAYER). BEST WINDOW OF OPPORTUNITY WILL BE FROM 08-12Z FRI. SYNOPTIC-SCALE FORCING WILL STRONGLY OPPOSE ANY MESOSCALE EFFECTS...GIVEN THE INCREASING SUBSIDENCE (INVERSION LEVELS TOPPING OUT BTWN 4-5 KFT) AND DRY AIR ENTRAINMENT INTO THE LLVL MIXED LAYER (850-700 MB MEAN RH`S FALLING TO AROUND 25-30%). NEVERTHELESS...STRONG LLVL CAA WILL GENERATE EXTREME OVER-WATER INSTBY (WATER-850 MB DELTA T`S APPROACHING 25C)...WITH ICE NUCLEI PRESENT WITHIN EVEN VERY SHALLOW MOIST CONVECTION. WILL CONTINUE TO GO WITH MENTION OF FLURRIES ATTM. STILL CAN NOT OUTRULE A STRONGER BAND DVLPG ALLOWING FOR SNOW SHOWERS TO DVLP OVER LWR VA ERN SHORE WITH SUCH AS COLD AIRMASS MODELS MAY BE UNDERDONE WITH FORCING/LIFT (ESP NEAR THE BORDER OF NEAR THE ACCOMACK/NORTHAMPTON BORDER AND SOUTHWARD. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/... DEEP TROUGH ALOFT SWINGS THROUGH THE FA LT FRI/FRI NGT. CNTR OF STRNG SFC HI PRES SLO TO BUILD EWD FM THE MIDWEST THROUGH FRI EVE...W/ CNTR ARRIVING OVR FA FOR LT FRI NGT AND SAT. DESPITE AMPLE SUNSHINE ON FRI...RDGS STRUGGLE TO REACH THE M/U20S ACRS FA (SEE CLIMO SXN BLO TO SEE WHEN IT WAS THIS COLD ARND THESE PARTS). EVEN THOUGH AMS QUITE DRY...STILL SOME CONCERN ABT SNOW SHOWERS OR FLURRIES OVR THE WTRS...THOUGH LLVL TRAJ MR NW THAN N (LESS THAN IDEAL FOR ANY PCPN INVOF ORF/NTU). HV KPT MENTION OF FLURRIES OVR THE WTRS. VRY COLD FRI NGT AS BLYR DCPLS...UNDER SKC AND W/ DWPTS AOB ZERO...XPCTG WDSPRD SINGLE DIGITS (AWAY FM THE LRGR CITIES/BAY- OCN). THIS AIRMASS IS IMPRESSIVELY COLD WHEN YOU CONSIDER THE ABSENCE OF SNOW COVER WHICH WOULD AID TO THE RADIATIONAL COOLING FURTHER. AT THIS TIME THE BEST CHANCE FOR READINGS BELOW ZERO WILL BE IN THE NORMALLY COLDER LOCALES...PARTICULARY SBY. NOT XPCTG ANY QUIK WRMUP ON SAT AS LLVL WAA SLO TO MATERIALIZE (HIGH OVERHEAD...LIMITED VERTICAL MIXING). EVENTUALLY...WNDS SHIFT TO MR SLY DRCTN...THAT IS NOT LIKELY B4 LT AFTN. HI TEMPS SAT ONLY FM THE M20S TO L30S. SUNDAY/SUN NIGHT...NEXT CLIPPER SYSTEM (NRN STREAM TROUGH) WILL PIVOT ACROSS THE GREAT LAKES AND OH VLY REGION. MEANWHILE...THE GFS/ECMWF/NAM/AND SREFS TO A SIMILAR DEGREE SHOW AN APPROACHING SRN STREAM JET STREAK/VORT LOBE LATE IN THE DAY...MOVING ACROSS THE MID ATLC COAST LATER SUN NIGHT. THE MODELS CONTINUE TO SHOW THESE 2 STREAMS OUT OF PHASE...HOWEVER WILL REMAIN WARY OF THE SRN STREAM WAVE AS THE GFS HAS TRENDED A LITTLE WETTER WITH THE 12Z RUN (ENSEMBLE MEAN QPF AROUND 0.1" OVER ERN VA AND NERN NC). OBVIOUSLY...A MORE PHASED (AMPLIFIED) UPPER PATTERN AND SLOWER- EVOLVING SFC RESPONSE/FARTHER S AND SLOWER-MOVING SFC LOW WOULD CREATE MORE CONCERNS OVER OUR FCST AREA...I.E. A MORE PROLONGED PERIOD OF MOIST/SRLY LLVL FLOW AND INCREASED POTENTIAL FOR A PERIOD OF BETTER ISENTROPIC LIFT AND STEADIER PRECIP. WILL HAVE TO KEEP AN EYE ON THIS ONE...ALONG WITH THE NEXT POTENTIAL WX MAKER LATE TUE/TUE NIGHT (SEE LONG TERM DISCUSSION). && .LONG TERM /MONDAY THROUGH THURSDAY/... LOW PRES AND TRAILING TROF DEPARTS TO THE NE ON MON. PRECIP/SNOW CHANCES DIMINISH DURING THE DAY MON AS HIGH PRES RIDGES IN FROM THE SW/W. NW FLOW AND INSTABILITY (CAA MOVING OVER WARMER BAY WATERS) WILL BE IN PLACE BEHIND THE TROF...WHICH MAY ALLOW FOR SOME BAY EFFECT SNOW PLUMES TO ONCE AGAIN INITIATE OVER THE CHES BAY. THUS WILL KEEP A SLIGHT CHANCE OF SNOW SHOWERS OVER THE LWR MD/VA ERN SHORE AND THE ADJACENT WATERS ON MON. THE RIDGE OF HIGH PRES WEAKENS AND RETREATS TO THE S ON MON NIGHT AS THE NEXT CLIPPER SYSTEM DIVES DOWN FROM THE GREAT LAKES...CROSSING THRU THE MID-ATLANTIC ON TUE INTO TUE NIGHT. GIVEN THE TRAJECTORY OF THE CLIPPER/TROF...DO NOT EXPECT ANY PRECIP WITH DOWNSLOPING FLOW OFF THE APPALACHIANS AND WITH THE UPSTREAM MOISTURE SOURCE (GREAT LAKES) BECOMING RATHER FROZEN AFTER THIS WEEK`S/WEEKEND`S `ARCTIC BLAST.` WILL HAVE TO BE WARY OF THIS NEXT SYSTEM...ESPECIALLY GIVEN THE SLOWER/DEEPENING TRENDS OF THE 12Z ECMWF. OTHERWISE... THIS CLIPPER WILL MOVE OFFSHORE ON WED AS THE NEXT RIDGE OF HIGH PRES MOVES IN FROM THE W. HIGH PRES THEN REMAINS IN CONTROL OF OUR WX THRU THU...WITH YET ANOTHER CLIPPER/TROF SKIRTING BY TO OUR N BY LATE NEXT WEEK. HIGH AND LOW TEMPS WILL NOT VARY MUCH IN THE EXTENDED...HIGHS GENERALLY IN THE UPR 30S TO MID 40S...LOWS IN THE UPR TEENS TO UPR 20S. && .AVIATION /04Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS AND GUSTY WNDS PREVAIL ACROSS THE AREA. ARCTIC BNDRY PASSED OFF THE COAST EARLIER TDY...AND COLDER AIR WILL CONTINUE TO FILTER INTO REGION OVRNGT. WNDS WILL BE NW-N 15-20 KTS AND GUSTY THRU THIS EVENING...THEN DIMINISH OVRNGT AS THE CORE OF HIGH PRES APPROACHES. VFR CONDS CONTINUE ON FRI AND SAT. INCREASING CLOUDS AND PSBL MVFR CONDS ON SUN WITH CHC OF PRECIPITATION. && .MARINE... SCA REMAINS IN EFFECT THROUGH EARLY FRI AFTERNOON. STRONG HIGH PRES WILL BUILD IN ACROSS THE REGION AS COLD ARCTIC AIR SPREADS OVER THE RELATIVELY WARMER WATERS. NW WINDS WILL CONTINUE TO AVERAGE AROUND 20-25 KT WITH GUSTS TO 30 KT. SEAS WILL GENERALLY BE BETWEEN 5-7 FT...WITH WAVES OF 3-5 FT OVER THE BAY. IN ADDITION...A FREEZING SPRAY ADVISORY REMAINS IN EFFECT FOR THE COASTAL WATERS FROM PARRAMORE ISLAND VA N TO FENWICK ISLAND DE. TEMPERATURES JUST ABOVE THE WATER SFC WILL FALL TO WELL BELOW FREEZING TONIGHT...AND WITH WINDS GREATER THAN 15 KNOTS...SEA SPRAY WILL BE BLOWING WHICH WILL THEN FREEZE ON VESSELS. THE CENTER OF THE HIGH WILL MOVE OVER THE WATERS FRI NIGHT THRU SAT NIGHT WHICH WILL ALLOW WINDS TO SIGNIFICANTLY DIMINISH AND SEAS TO SUBSIDE. THE NEXT FRONTAL SYSTEM/TROF WILL MOVE ACROSS THE WATERS LATE SAT NIGHT THRU SUN...AND WINDS/SEAS WILL ONCE AGAIN INCREASE /BUILD (ALTHO NOT AS HIGH AS THE CURRENT EVENT). HIGH PRES BUILDS BACK IN ON MON...WITH YET ANOTHER TROF CROSSING THE WATERS BY NEXT TUE. && .CLIMATE... VERY COLD WEATHER EXPECTED ON FRIDAY (THE 16TH) INTO THE MORNING OF SAT (THE 17TH)...BUT SINCE THIS IS CLIMATOLOGICALLY RIGHT AROUND THE COLDEST TIME OF YEAR...RECORD LOWS AND/OR RECORD LOW MAX TEMPERATURES APPEAR UNLIKELY AT THE MAIN CLIMATE SITES (RICHMOND/NORFOLK/SALISBURY). STILL...IT DOES LOOK TO BE THE COLDEST CONDITIONS WE HAVE EXPERIENCED IN A FEW YEARS: FCST HIGH FOR FRIDAY: RICHMOND.....FRI FCST HIGH: 27 F (LAST TIME HIGH WAS COLDER THAN 30 F OCCURRED FEB 6TH 2007) NORFOLK......FRI FCST HIGH: 29 F (LAST TIME HIGH WAS COLDER THAN 30 F OCCURRED JAN 28TH 2005) SALISBURY....FRI FCST HIGH: 23 F (LAST TIME HIGH WAS COLDER THAN 25 F OCCURRED FEB 6TH 2007). REC LOWS SAT JAN 17TH... RIC... -1 (1977) ORF... 5 (1977) SBY... -6 (1965) && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...WIND CHILL ADVISORY FROM 4 AM TO 10 AM EST FRIDAY FOR MDZ021>025. NC...NONE. VA...WIND CHILL ADVISORY FROM 4 AM TO 10 AM EST FRIDAY FOR VAZ048- 049-060>062-065>069-079. MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST FRIDAY FOR ANZ630>633-650- 652-654-656-658. FREEZING SPRAY ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ650-652. && $$ SYNOPSIS...BKH NEAR TERM...BKH/CCW SHORT TERM...BKH LONG TERM...JRL AVIATION...JEF MARINE...JRL CLIMATE... md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 337 AM EST THU JAN 15 2009 .SYNOPSIS... LOW PRESSURE AND ITS ASSOCIATED COLD FRONT WILL MOVE OFF THE COAST THIS MORNING. VERY COLD TEMPERATURES ARE EXPECTED BEHIND THIS SYSTEM THROUGH THE FIRST PART OF THE WEEKEND. UPPER LEVEL LOW PRESURE WILL CONTINUE TO INFLUENCE THE WEATHER OF THE MID ATLANTIC REGION SUNDAY THROUGH TUESDAY. HIGH PRESSURE WILL MOVE INTO THE REGION FOR THE SECOND HALF OF THE WEEK. && .NEAR TERM /TODAY/... AS W/ YDA`S DSCN I`M INCLUDING THE CLIMATE SXN BLO WRITTEN BY THE DAYSHIFT TEAM. BUT I CONT TO DO SOME RESEARCH ON COLD WX AT THE MAJOR THREE AIRPORTS. MORE "INTERESTING TO NOTES" - IN PAST 10 YRS DCA HAS ONLY BEEN SUB TEN DEGS ONCE - REACHING +8 ON 1/10/04. BWI HAS DONE IT 17 TIMES...IAD 24...W/ THE LOWEST OF +1 ON 12/7/02. BUT NONE HV BEEN SUB ZERO IN PAST TEN YRS. AT DCA NO JAN RECORD MIN HAS BEEN SET SINCE 1994. SO IN SPITE OF THE APRCHG COLD AIR - THE STRONGEST I`VE SEEN IN A LONG TIME HERE...COLD DOESN`T SEEM TO BE AS COLD AS IT USED TO. BUT IT STILL WL BE COLD FOR THE NEXT SVRL DAYS AS THE WORLD TURNS IT`S EYES TO ONE OF THE MOST IMPORTANT STRETCHES OF DAYS IN DC HISTORY. 04Z SFC ANLYS SHOWS A RLTVLY WEAK LOW PRES AREA CENTERED OVR THE NRN PART OF THE CWA WHICH IS RESPONSIBLE FOR THE SNOWS BEING RCVD IN THE WRN PART OF THE CWA. RCVD A CALL FM A FROSTBURG SPOTTER ARND 1 AM REPORTING 2.5" HAS FALLEN SINCE THIS AFTN OF XTRMLY POWDERY SNOW. HV SEEN LIQUID/SNOW RATIOS OF 20-1 DISCUSSED IN THE WX CHAT ROOM...WHICH SEEMS REASONABLE. THIS WL CONT THRU THE MRNG HRS..ANOTHER INCH OR TWO PSBL IN THE WRN HIGHLANDS SO WINT WX ADVSRY RMNS INTACT. ANLYS ALSO SHOWED THE STRONGEST HIGH PRES I`VE SEEN IN AWHILE - ALMOST 1046 MB OVR NRN ND. CURRENTLY -31 AT DEVILS LAKE. BRRRR. WIND CHILL ADVSRY - THE 0730Z WIND CHILL PLOT SHOWS NO VALUES L.T. +10. WE HV IT GOING INTO EFFECT AT 09Z...WHICH DOESN`T SEEM LKLY TO ME. I`M GOING TO PUSH THE START BACK TO 12Z...AND HONESTLY I SEE THIS AS MARGINAL AT BEST. BUT SOME -5 WIND CHILLS COULD BE REACHED TDA. RMDR OF CWA TDA...RDR SHOWS S- ACROSS THE NRN AND WRN PARTS OF THE CWA. HRR RUC SHOW THIS CONTINUING THRU THE MRNG HRS THEN TAPERING OFF. HIGH PRES WL SPEND THE DAY BUILDING INTO THE RGN WHICH WL MAKE IT BRZY ALTHO NOT NEAR ADVSRY LVLS. TEMPS WL NOT DO MUCH IF ANY CLIMBING TDA. HIGHS RANGING FM TEENS FAR W TO LM30S ALONG THE BAY. && .SHORT TERM /TONIGHT/... HIGH PRES CONTS TO BUILD IN TNGT. NW WINDS ARND 10 KT AFTR 00Z. TEMPS COULD GO SUB ZERO IN THE HIGHLANDS...M TEENS IN LOWER SRN MD. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... IN TERMS OF AMBIENT TEMP...THU NIGHT WILL LIKELY BE THE COLDEST OF THE YEAR. THE ARCTIC INTRUSION OF THE MID ATLC WILL BE AT IT/S MAXIMUM EFFECT DURING THE PRE-DAWN HRS FRI MORNING. THE ERN EDGE OF A +1045MB SFC HIGH WILL BE BUILDING ACROSS THE MID ATLC. FORTUNATELY...EVEN W/ TEMPS DROPPING INTO THE SINGLE DIGITS AND INTO SUBZERO READINGS OVERNIGHT...WINDS ARE EXPECTED TO DROP OFF VERY LIGHT/VRB. WINDS STILL MAY BE A FACTOR FOR THE EVNG AND LATE NIGHT HRS THO...SO WIND CHILL PRODUCTS MAY BE WARRANTED FOR THE HRS PRECLUDING WINDS DROPPING OFF OVERNIGHT. HOLDING OFF A WIND CHILL WATCH FOR THE WRNMOST ZONES. THE MOST LIKELY SCENARIO BEING A WIND CHILL ADVISORY WEST OF THE VA BLUE RIDGE...INCLUDING THE SHENANDOAH VLY AND SURROUNDING AREAS OF THE CNTRL APLCNS. THE SFC HIGH CONTINUES TO MOVE TOWARD THE MID ATLC DURING THE DAY FRIDAY...WEAKENING AS ANOTHER QUICK VORT LOBE SPEEDS TOWARD THE REGION FROM THE UPPER MIDWEST. THE ELONGATED HIGH OVER THE LENGTH OF THE EAST COAST THEN GETS SPLIT BY THE INCOMING LOW. AS THE LOW SLIDES THRU THE GRT LKS REGION...IT STALLS OVER WRN NY AS A BACKSIDE UPPER TROF DEEPENS INTO THE MID MISSISSIPPI VLY. HOW DEEP AND THE PROXIMITY OF THIS TROF AXIS WILL BE KEY IN DETERMINING WHETHER ANY OF THE ASSOCIATED MOISTURE EITHER GETS DRAWN UP INTO THE MID ATLC FROM THE GULF COAST REGION...AND/OR GETS PUSHED PAST THE CNTRL APLCNS SUNDAY INTO THE OVERNIGHT HRS. GFS PAINTING A SOLUTION SIMILAR TO THE EVENTS OF EARLIER THIS WEEK...W/ AN AREA OF BROAD LAKE EFFECT/UPSLOPE SNOWS ACROSS THE OHIO VLY...DISSIPATING OVER THE MTNS. A WEAK AND THINLY STRETCHED BAND OF LOW LEVEL GULF MOISTURE THEN GETS FORCED UP THE ERN SEABOARD LATE SUNDAY AND ALL THIS ACTIVITY SLIDES OFF THE ATLC COAST BY EARLY MONDAY. FOR NOW...A BROAD LOW CHANCE POP AREA WILL SUFFICE W/ THE UNCERTAINTY IN STRENGTH/TIMING OF ANY ONE OF THESE ELEMENTS LINING UP DURING THE LATER PART OF THE WEEKEND. ACROSS THE WRN HALF OF THE COUNTRY...A HIGH PRESSURE RIDGE BUILDS DUE NORTH ALL THE WAY INTO THE NW TERRITORIES. THE EFFECT ON THE ERN HALF OF THE COUNTRY IS AN UPPER TROF THAT PUSHES DOWN OVER THE GULF OF MEXICO. AT LEAST A COUPLE MORE UPPER VORT LOBES WILL SLIDE DOWN THE BACKSIDE OF THE UPPER TROF INTO THE MID ATLC THRU MID WEEK. NEITHER OF THE UPPER WAVES EXPECTED DO MUCH MORE THAN REINFORCE THE SUBFREEZING TEMPS AND POSSIBLY SLIDE ACROSS AREAS OF SCATTERED FLURRIES W/ EACH PASSAGE. THE WRN RIDGE THEN BEGINS TO BUILD INTO THE CNTRL AND ERN STATES TOWARD THE END OF NEXT WEEK. && .AVIATION /TODAY THROUGH MONDAY/... VFR CONDS...ISOLD SNSH PSBL AT MAJOR AIRPORTS THIS MRNG W/ SOME DEGRADATION TO CIGS/VSBY. VFR CONDS TNGT. BREEZY WLY WINDS ON FRIDAY. HIGH PRESSURE FOR FRI/SAT. A QUICK MOVING UPPER LOW WILL APPROACH THE REGION ON SUNDAY...W/ SOME SCATTERED SNOW SHOWERS POSSIBLE BUT VERY LIGHT ACTIVITY EXPECTED. LITTLE MORE THAN BREEZY CONDITIONS EXPECTED EARLY NEXT WEEK AND POSSIBLE FLURRIES AT TIMES THRU MID WEEK. && .MARINE... SCA IN EFFECT AS COLDER/DENSE AIR POURS INTO MID ATLC FOR TDA AND TNGT. DOUBTFUL TOO MANY PLEASURE MARINERS ARE OUT THERE - TPLM WATER TEMP IS 37. MARGINAL SCA CONDITIONS ON FRIDAY AFTN/EVNG. WINDS EXPECTED TO STAY FAIRLY LIGHT ACROSS THE WATERS THRU THE WEEKEND INTO THE MON AFTN...FROM ANOTHER UPPER LEVEL SYSTEM. HIGH PRES WILL THEN GRADUALLY BUILD INTO THE REGION STARTING MID WEEK. && .CLIMATE... VERY COLD WEATHER IS STILL EXPECTED THIS FRIDAY /16 JAN/ INTO SATURDAY MORNING /17 JAN/. HOWEVER...SINCE THIS IS NEAR THE CLIMATOLOGICALLY COLDEST TIME OF YEAR...RECORD LOWS AND/OR RECORD LOW MAXIMUM TEMPERATURES ARE UNLIKELY IN THE BALTIMORE/WASHINGTON METROPOLITAN AREA. DESPITE GUIDANCE SUGGESTING SLIGHTLY HIGHER TEMPERATURES ON SATURDAY MORNING...IT STILL DOES LOOK TO BE SOME OF THE COLDEST AIR IN THE PAST 15 YEARS. PLEASE NOTE THAT IT WAS SIGNIFICANTLY COLDER DURING A COLD SPELL IN MID JANUARY 1994 AT BWI/DCA/IAD. BELOW ARE THE LATEST FORECAST MAXIMA FOR FRIDAY AND MINIMA FOR SATURDAY AT BWI/DCA/IAD WITH RECENT TIMES TEMPERATURES NEARED THESE VALUES...AS WELL AS RECORD LOWEST MAX ON 16 JAN AND RECORD LOW ON 17 JAN. BWI...FRI FCST HIGH: 20 F /HIGH OF 19 F ON JAN 10 2004 AND FEB 4 1996 AND 20 ON FEB 5 2007...RECORD LOW MAXIMUM OF 14 F IN 1893/ DCA...FRI FCST HIGH: 20 F /HIGH OF 17 F ON FEB 4 1996 AND 20 F ON FEB 3 1996 AND 21 F ON JAN 10 2004...RECORD LOW MAXIMUM OF 15 F IN 1893/ IAD...FRI FCST HIGH: 19 F /HIGH OF 14 F ON FEB 4 1996 AND 19 F ON JAN 17-18 1997 AND 20 ON FEB 5 2007...RECORD LOW MAXIMUM OF 14 IN 1972 AND 1996/ BWI...SAT FCST LOW: 5 F /LOW OF 1 ON JAN 19 1997 AND 4 ON FEB 6 1996 AND 5 ON JAN 18 2003...RECORD LOW OF -7 IN 1982/ DCA...SAT FCST LOW: 9 F /LOW OF 8 F ON JAN 10 2004 AND 9 ON FEB 4 1996...RECORD LOW OF -5 IN 1982/ IAD...SAT FCST LOW: 3 F /LOW OF 1 F ON DEC 7 2002 AND 3 ON JAN 29 2004...RECORD LOW OF -7 IN 1982/ && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR MDZ501-502. WIND CHILL ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR MDZ501- 502. VA...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR VAZ021. WIND CHILL ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR VAZ021. WV...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR WVZ054- 501>504. WIND CHILL ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR WVZ054- 501>504. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR ANZ530>537. && $$ PRODUCTS...WOODY!/GMS CLIMATE...BPP/BJL md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 700 PM EST FRI JAN 16 2009 UPDATED FOR 00Z AVIATION DISCUSSION .SYNOPSIS... WATER VAPOR IMAGERY AND RUC ANALYSIS CONTINUE TO SHOW AN AMPLIFIED PATTERN ACROSS NAMERICA WITH A PRONOUNCED RIDGE OVER THE W AND A DEEP TROF OVER THE E. A WELL DEFINED SHORTWAVE TROF WAS DROPPING SE THRU ALBERTA/SASKATCHEWAN/MANITOBA. IN THE SHORT TERM...THIS WILL BE THE MAIN FEATURE OF INTEREST AS IT MOVES INTO THE UPPER MISSISSIPPI VALLEY/GREAT LAKES REGION SAT. ARCTIC AIRMASS OVER THE UPPER LAKES REGION IS BEGINNING TO EASE UNDER DEVELOPING WAA PATTERN AHEAD OF SHORTWAVE TROF. THIS HAS ALLOWED TEMPS TO RISE INTO THE SINGLE DIGITS ABOVE ZERO ACROSS THE FCST AREA THIS AFTN. VIS SATELLITE IMAGERY AND KMQT RADAR SHOW DIMINISHING LES SHIFTING UNDER BACKING LOW-LEVEL WINDS. LAST OF THE LES IS CURRENTLY AFFECTING THE TIP OF THE KEWEENAW PENINSULA AND AREAS FROM PICTURED ROCKS ACROSS NRN LUCE COUNTY. HIGH RES POLAR ORBITER IMAGE TODAY SHOWS SIGNIFICANT ICE FORMATION HAS OCCURRED ACROSS LAKE SUPERIOR OVER THE LAST COUPLE OF DAYS. BKN ICE EXTENDS WNW FROM THE PORCUPINE MTNS TO THE MN SHORE. MORE ICE EXTENDS FROM THE MN/ONTARIO SHORE TO ISLE ROYALE...AND A LARGE AREA OF ICE HAS FORMED W OF A LINE ROUGHLY FROM SHOT PT TO MANITOU ISLAND. && .SHORT TERM (TONIGHT THRU SAT AFTN)... LAST OF THE LES OVER THE TIP OF THE KEWEENAW AND FROM AROUND GRAND MARAIS EWD WILL END THIS EVENING AS WINDS CONTINUE TO BACK AHEAD OF APPROACHING SHORTWAVE TROF AND ASSOCIATED SFC TROF/LOW PRES. ACCUMULATIONS WILL BE WELL UNDER 1 INCH. BEFORE CLOUDS INCREASE/THICKEN FROM THE NW...TEMPS MAY CRASH UNDER LIGHT WINDS. FAVORED THE LOW END OF MOS GUIDANCE WITH SINGLE DIGITS BLO ZERO EXPECTED OVER MUCH OF THE FCST AREA. WILL NEED TO MONITOR TRENDS OVER THE ERN FCST AREA THIS EVENING AS THAT AREA HAS BEST POTENTIAL TO FALL BLO FCST MINS. ATTENTION THEN TURNS TO APPROACHING SHORTWAVE TROF. FAIRLY STRONG ISENTROPIC ASCENT PATTERN DEVELOPS LATE TONIGHT/SAT MORNING. MIXING RATIOS OF 2G/KG ARE AVBL ON THE 285K SFC (AROUND 700MB). WITH 6-9HRS OF LIFT...ACCUMULATIONS SHOULD RANGE FROM 2-3INCHES BY THE TIME SNOW DIMINISHES SAT. HOWEVER...GFS/NAM FCST SOUNDINGS SHOW A DEEP LAYER OF TEMPS FAVORABLE FOR DENDRITIC SNOW GROWTH FROM NEAR THE SFC TO AROUND 10KFT OR SO. THUS...SNOW TO WATER RATIOS MAY BE QUITE HIGH. WHILE AN ADVY LOOKS MARGINAL ATTM FOR THE FCST AREA...IT APPEARS SYSTEM WILL BE BECOMING BETTER ORGANIZED WITH MORE FOCUSED FORCING AS IT TRACKS SE. HAVE THUS OPTED FOR AN ADVY ACROSS THE S FROM IRON COUNTY TO SRN SCHOOLCRAFT FOR ROUGHLY 3-5 INCHES OF SNOW. MORE CHALLENGING PART OF THE FCST IS WHAT MAY TRANSPIRE CLOSE TO LAKE MICHIGAN. ALTHOUGH EACH MODEL SHOWS IMPORTANT DETAIL DIFFERENCES WITH LOW-LEVEL WINDS ACROSS NRN LAKE MICHIGAN...CONSENSUS IS THAT WINDS WILL BE FAVORABLE FOR AT LEAST SOME ENHANCEMENT OVER SE DELTA/SRN SCHOOLCRAFT. HOWEVER...HAVE CONCERNS THAT SIGNIFICANT ENHANCEMENT/HVY SNOW ACCUMULATIONS MAY OCCUR SOMEWHERE IN THAT AREA GIVEN THE DEEP DENDRITIC SNOW GROWTH ZONE AND POTENTIAL FOR SHARP CONVERGENCE TO SET UP FOR A TIME UNDER SFC TROF THAT WILL BE DEVELOPING SOUTHEASTWARD ACROSS NRN LAKE MICHIGAN. FOR NOW...INCLUDED THE HIGHEST SNOW ACCUMULATIONS AROUND 6 INCHES ACROSS SE DELTA/SRN SCHOOLCRAFT...BUT POTENTIAL IS THERE FOR SIGNIFICANTLY MORE IF WIND FIELDS SET UP JUST RIGHT. WILL NEED TO MONITOR MODEL RUNS TONIGHT TO SEE IF A TREND DEVELOPS FOR MORE FOCUSED SRLY CONVERGENCE IN THAT AREA. .LONG TERM (SATURDAY NIGHT THROUGH NEXT FRIDAY)... POSTIVE PNA PATTERN WITH A RIDGE OVR WESTERN NOAM AND TROUGH OVR EASTERN NOAM CONTINUES THROUGH NEXT WEEK. RIDGE/WARMER AIR OVR WEST CONUS DOES EDGE INTO UPR MISSISSIPPI RIVER VALLEY AND WESTERN GREAT LAKES EARLY NEXT WEEK. BUT...THE BRIEF WARM UP IS QUICKLY REPLACED BY ANOTHER SHOT OF COLD AIR LATE NEXT WEEK AS THE TROUGH DEEPENS. EXTENDED MODELS ONLY SHOWING LOOSE AGREEMENT IN THE OVERALL PATTERN AND DIFFER EVEN MORE ON DETAILS. THIS RESULTS IN BLO NORMAL CONFIDENCE IN THE DAY 4-7 FORECAST. IN THE WAKE OF THE SATURDAY CLIPPER LOW...EXPECT RESURGENCE IN LK EFFECT AS H85 TEMPS FALL OFF TOWARD -15C. SOUNDINGS INDICATE INVERSIONS UP TO 5KFT AND DEEP MOISTURE LEFT OVR FM THE DEPARTING LOW PRESSURE SYSTEM. PROGGED LIFT IS WITHIN MORE FAVORABLE SNOW GROWTH REGION AS WELL. 925-850MB WINDS ARE LIGHT WITH SPEEDS UP TO 15 KT SO THE SNOW SHOWERS WILL TEND TO HANG ALONG THE SHORE OR MOVE JUST INLAND. DUE TO THE FAVORABLE SNOW GROWTH LINED UP WITH THE LK EFFECT MOIST LAYER...MODERATE SNOW ACCUMS ARE POSSIBLE SUNDAY NIGHT INTO MONDAY. AT THIS POINT...MORE PERSISTENT SNOW SHOWERS LOOK TO SET UP OVR WESTERN AND NCNTRL AREAS AS LOW-LEVEL WINDS ARE FM N TO NNE. PINNING DOWN WHERE THE HEAVIER SNOW MAY OCCUR BECOMING MORE MUDDLED DUE TO INCREASING ICE COVER ON LK SUPERIOR. ONGOING LK EFFECT ON MONDAY WILL HAVE OPPORTUNITY TO INCREASE AS SHORTWAVE DROPS ALMOST NORTH TO SOUTH ACROSS UPR LAKES. SLIGHTLY BACKING WINDS MONDAY MORNING SHOULD SHIFT BACK MORE NRLY BY LATE DAY INTO THE EVENING. SHARPNESS OF WIND SHIFT MORE IN QUESTION. SINCE THIS WAVE IS JUST APPEARING IN GUIDANCE TODAY...DID NOT HIT IT TOO HARD YET. INCREASED POPS ALONG ALL OF LAKE SUPERIOR. AFTER THIS SFC TROUGH SHIFTS THROUGH...NW LK EFFECT WILL PERSIST THROUGH TUESDAY. WINDS BACK AHEAD OF COLD FRONT DROPPING INTO THE UPR LAKES LATE NEXT WEEK. KEPT POPS ON WED ONLY CONFINED TO KEWEENAW IN EXPECTED SW FLOW IN THE LOW-LEVELS. BEYOND WED NIGHT...CHOSE TO DISCOUNT 12Z GFS SOLUTION AS IT COMPLETELY BROKE CONTINUITY WITH PREVIOUS RUNS AND MAJORITY OF OTHER GUIDANCE BY KEEPING SW FLOW ALOFT OVR UPR LAKES AND DELAYING PUSH OF COLD AIR UNTIL NEXT FRIDAY. FORECAST IS MUCH MORE IN LINE WITH 00Z/12Z ECMWF AND LATEST HPC GUIDANCE. AFTER A PERIOD OF SNOW ALONG THE TROUGH WEDNESDAY NIGHT INTO THURSDAY...MORE LK EFFECT DEVELOPS IN N/NW FLOW AREAS INTO FRIDAY. COLD TEMPS RETURN WITH READINGS FALLING BACK BLO NORMAL. HOWEVER...TEMPS DO NOT LOOK TO FALL TO LEVELS SEEN THIS WEEK. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... AT KCMX...VFR CONDITIONS WILL PREVAIL THIS EVENING WITH SRLY FLOW AHEAD OF THE NEXT LOW. A CLIPPER SYSTEM WILL BRING A RETURN OF -SN LATE TONIGHT WITH IFR CONDITIONS EXPECTED BEFORE DAYBREAK WHICH WILL CONTINUE THROUGH THE MORNING. AS THE SNOW DIMINISHES IN THE EARLY AFTERNOON...CONDITIONS SHOULD IMPROVE TO MVFR. AT KSAW...DRY DOWNSLOPING W TO SW FLOW WILL RESULT IN VFR CONDITIONS PREVAILING THROUGH MUCH OF TONIGHT. A CLIPPER SYSTEM DROPPING INTO THE AREA SAT WILL BRING -SN AND IFR VIS/CIGS FOR SAT MORNING. AS THE SNOW TAPERS OFF...SOME IMPROVEMENT IS EXPECTED BY LATE SATURDAY AFTERNOON TO MVFR CONDITIONS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HEAVY FREEZING SPRAY SHOULD END OVER MOST OF LAKE SUPERIOR BY SUNRISE SAT. WINDS ARE EXPECTED TO STAY BLO GALE FORCE THRU THIS FCST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 AM TO 12 PM CST SATURDAY FOR MIZ010. WINTER WEATHER ADVISORY FROM 7 AM TO 7 PM EST SATURDAY FOR MIZ013-014. WINTER WEATHER ADVISORY FROM 6 AM TO 3 PM CST SATURDAY FOR MIZ011-012. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST SATURDAY FOR LSZ263- 264-266-267. HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ265. && $$ SYNOPSIS/SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 515 PM EST FRI JAN 16 2009 .SYNOPSIS... WATER VAPOR IMAGERY AND RUC ANALYSIS CONTINUE TO SHOW AN AMPLIFIED PATTERN ACROSS NAMERICA WITH A PRONOUNCED RIDGE OVER THE W AND A DEEP TROF OVER THE E. A WELL DEFINED SHORTWAVE TROF WAS DROPPING SE THRU ALBERTA/SASKATCHEWAN/MANITOBA. IN THE SHORT TERM...THIS WILL BE THE MAIN FEATURE OF INTEREST AS IT MOVES INTO THE UPPER MISSISSIPPI VALLEY/GREAT LAKES REGION SAT. ARCTIC AIRMASS OVER THE UPPER LAKES REGION IS BEGINNING TO EASE UNDER DEVELOPING WAA PATTERN AHEAD OF SHORTWAVE TROF. THIS HAS ALLOWED TEMPS TO RISE INTO THE SINGLE DIGITS ABOVE ZERO ACROSS THE FCST AREA THIS AFTN. VIS SATELLITE IMAGERY AND KMQT RADAR SHOW DIMINISHING LES SHIFTING UNDER BACKING LOW-LEVEL WINDS. LAST OF THE LES IS CURRENTLY AFFECTING THE TIP OF THE KEWEENAW PENINSULA AND AREAS FROM PICTURED ROCKS ACROSS NRN LUCE COUNTY. HIGH RES POLAR ORBITOR IMAGE TODAY SHOWS SIGNIFICANT ICE FORMATION HAS OCCURRED ACROSS LAKE SUPERIOR OVER THE LAST COUPLE OF DAYS. BKN ICE EXTENDS WNW FROM THE PORCUPINE MTNS TO THE MN SHORE. MORE ICE EXTENDS FROM THE MN/ONTARIO SHORE TO ISLE ROYALE...AND A LARGE AREA OF ICE HAS FORMED W OF A LINE ROUGHLY FROM SHOT PT TO MANITOU ISLAND. && .SHORT TERM (TONIGHT THRU SAT AFTN)... LAST OF THE LES OVER THE TIP OF THE KEWEENAW AND FROM AROUND GRAND MARAIS EWD WILL END THIS EVENING AS WINDS CONTINUE TO BACK AHEAD OF APPROACHING SHORTWAVE TROF AND ASSOCIATED SFC TROF/LOW PRES. ACCUMULATIONS WILL BE WELL UNDER 1 INCH. BEFORE CLOUDS INCREASE/THICKEN FROM THE NW...TEMPS MAY CRASH UNDER LIGHT WINDS. FAVORED THE LOW END OF MOS GUIDANCE WITH SINGLE DIGITS BLO ZERO EXPECTED OVER MUCH OF THE FCST AREA. WILL NEED TO MONITOR TRENDS OVER THE ERN FCST AREA THIS EVENING AS THAT AREA HAS BEST POTENTIAL TO FALL BLO FCST MINS. ATTENTION THEN TURNS TO APPROACHING SHORTWAVE TROF. FAIRLY STRONG ISENTROPIC ASCENT PATTERN DEVELOPS LATE TONIGHT/SAT MORNING. MIXING RATIOS OF 2G/KG ARE AVBL ON THE 285K SFC (AROUND 700MB). WITH 6-9HRS OF LIFT...ACCUMULATIONS SHOULD RANGE FROM 2-3INCHES BY THE TIME SNOW DIMINISHES SAT. HOWEVER...GFS/NAM FCST SOUNDINGS SHOW A DEEP LAYER OF TEMPS FAVORABLE FOR DENDRITIC SNOW GROWTH FROM NEAR THE SFC TO AROUND 10KFT OR SO. THUS...SNOW TO WATER RATIOS MAY BE QUITE HIGH. WHILE AN ADVY LOOKS MARGINAL ATTM FOR THE FCST AREA...IT APPEARS SYSTEM WILL BE BECOMING BETTER ORGANIZED WITH MORE FOCUSED FORCING AS IT TRACKS SE. HAVE THUS OPTED FOR AN ADVY ACROSS THE S FROM IRON COUNTY TO SRN SCHOOLCRAFT FOR ROUGHLY 3-5 INCHES OF SNOW. MORE CHALLENGING PART OF THE FCST IS WHAT MAY TRANSPIRE CLOSE TO LAKE MICHIGAN. ALTHOUGH EACH MODEL SHOWS IMPORTANT DETAIL DIFFERENCES WITH LOW-LEVEL WINDS ACROSS NRN LAKE MICHIGAN...CONSENSUS IS THAT WINDS WILL BE FAVORABLE FOR AT LEAST SOME ENHANCEMENT OVER SE DELTA/SRN SCHOOLCRAFT. HOWEVER...HAVE CONCERNS THAT SIGNIFICANT ENHANCEMENT/HVY SNOW ACCUMULATIONS MAY OCCUR SOMEWHERE IN THAT AREA GIVEN THE DEEP DENDRITIC SNOW GROWTH ZONE AND POTENTIAL FOR SHARP CONVERGENCE TO SET UP FOR A TIME UNDER SFC TROF THAT WILL BE DEVELOPING SOUTHEASTWARD ACROSS NRN LAKE MICHIGAN. FOR NOW...INCLUDED THE HIGHEST SNOW ACCUMULATIONS AROUND 6 INCHES ACROSS SE DELTA/SRN SCHOOLCRAFT...BUT POTENTIAL IS THERE FOR SIGNIFICANTLY MORE IF WIND FIELDS SET UP JUST RIGHT. WILL NEED TO MONITOR MODEL RUNS TONIGHT TO SEE IF A TREND DEVELOPS FOR MORE FOCUSED SRLY CONVERGENCE IN THAT AREA. .LONG TERM (SATURDAY NIGHT THROUGH NEXT FRIDAY)... POSTIVE PNA PATTERN WITH A RIDGE OVR WESTERN NOAM AND TROUGH OVR EASTERN NOAM CONTINUES THROUGH NEXT WEEK. RIDGE/WARMER AIR OVR WEST CONUS DOES EDGE INTO UPR MISSISSIPPI RIVER VALLEY AND WESTERN GREAT LAKES EARLY NEXT WEEK. BUT...THE BRIEF WARM UP IS QUICKLY REPLCED BY ANOTHER SHOT OF COLD AIR LATE NEXT WEEK AS THE TROUGH DEEPENS. EXTENDED MODELS ONLY SHOWING LOOSE AGREEMENT IN THE OVERALL PATTERN AND DIFFER EVEN MORE ON DETAILS. THIS RESULTS IN BLO NORMAL CONFIDENCE IN THE DAY 4-7 FORECAST. IN THE WAKE OF THE SATURDAY CLIPPER LOW...EXPECT RESURGENCE IN LK EFFECT AS H85 TEMPS FALL OFF TOWARD -15C. SOUNDINGS INDICATE INVERSIONS UP TO 5KFT AND DEEP MOISTURE LEFT OVR FM THE DEPARTING LOW PESSURE SYSTEM. PROGGED LIFT IS WITHIN MORE FAVORABLE SNOW GROWTH REGION AS WELL. 925-850MB WINDS ARE LIGHT WITH SPEEDS UP TO 15 KT SO THE SNOW SHOWERS WILL TEND TO HANG ALONG THE SHORE OR MOVE JUST INLAND. DUE TO THE FAVORABLE SNOW GROWTH LINED UP WITH THE LK EFFECT MOIST LAYER...MODERATE SNOW ACCUMS ARE POSSIBLE SUNDAY NIGHT INTO MONDAY. AT THIS POINT...MORE PERSISTENT SNOW SHOWERS LOOK TO SET UP OVR WESTERN AND NCNTRL AREAS AS LOW-LEVEL WINDS ARE FM N TO NNE. PINNING DOWN WHERE THE HEAVIER SNOW MAY OCCUR BECOMING MORE MUDDLED DUE TO INCREASING ICE COVER ON LK SUPERIOR. ONGOING LK EFFECT ON MONDAY WILL HAVE OPPORTUNITY TO INCREASE AS SHORTWAVE DROPS ALMOST NORTH TO SOUTH ACROSS UPR LAKES. SLIGHTLY BACKING WINDS MONDAY MORNING SHOULD SHIFT BACK MORE NRLY BY LATE DAY INTO THE EVENING. SHARPNESS OF WIND SHIFT MORE IN QUESTION. SINCE THIS WAVE IS JUST APPEARING IN GUIDANCE TODAY...DID NOT HIT IT TOO HARD YET. INCREASED POPS ALONG ALL OF LAKE SUPERIOR. AFTER THIS SFC TROUGH SHIFTS THROUGH...NW LK EFFECT WILL PERSIST THROUGH TUESDAY. WINDS BACK AHEAD OF COLD FRONT DROPPING INTO THE UPR LAKES LATE NEXT WEEK. KEPT POPS ON WED ONLY CONFINED TO KEWEENAW IN EXPECTED SW FLOW IN THE LOW-LEVELS. BEYOND WED NIGHT...CHOSE TO DISCOUNT 12Z GFS SOLUTION AS IT COMPLETELY BROKE CONTINUITY WITH PREVIOUS RUNS AND MAJORITY OF OTHER GUIDANCE BY KEEPING SW FLOW ALOFT OVR UPR LAKES AND DELAYING PUSH OF COLD AIR UNTIL NEXT FRIDAY. FORECAST IS MUCH MORE IN LINE WITH 00Z/12Z ECMWF AND LATEST HPC GUIDANCE. AFTER A PERIOD OF SNOW ALONG THE TROUGH WEDNESDAY NIGHT INTO THURSDAY...MORE LK EFFECT DEVELOPS IN N/NW FLOW AREAS INTO FRIDAY. COLD TEMPS RETURN WITH READINGS FALLING BACK BLO NORMAL. HOWEVER...TEMPS DO NOT LOOK TO FALL TO LEVELS SEEN THIS WEEK. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... AT KCMX...AS A HIGH PRES RIDGE BUILDS INTO THE WESTERN GREAT LAKES AND WINDS BACK TO WSW THIS AFTERNOON...EXPECT LES BANDS TO SHIFT NORTH OF KCMX. THIS WILL BRING A TRANSITION FROM IFR/LIFR CONDITIONS IN -SHSN TO VFR CONDITIONS BY SUNSET. CLIPPER SYSTEM WILL BRING A RETURN OF -SN LATE IN THE NIGHT WITH IFR CONDITIONS EXPECTED BEFORE DAYBREAK. AT KSAW...DRY DOWNSLOPING W TO SW FLOW WILL RESULT IN VFR CONDITIONS PREVAILING THRU AT LEAST THE EVENING HRS. CLIPPER SYSTEM DROPPING INTO THE AREA SAT WILL BRING -SN AND IFR VIS/CIGS FOR SAT MORNING. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HEAVY FREEZING SPRAY SHOULD END OVER MOST OF LAKE SUPERIOR BY SUNRISE SAT. WINDS ARE EXPECTED TO STAY BLO GALE FORCE THRU THIS FCST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 AM TO 12 PM CST SATURDAY FOR MIZ010. WINTER WEATHER ADVISORY FROM 7 AM TO 7 PM EST SATURDAY FOR MIZ013-014. WINTER WEATHER ADVISORY FROM 6 AM TO 3 PM CST SATURDAY FOR MIZ011-012. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST SATURDAY FOR LSZ263- 264-266-267. HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ265. && $$ SYNOPSIS/SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 346 AM EST FRI JAN 16 2009 .SYNOPSIS.../ISSUED AT 345 AM/ ARCTIC AIR WILL REMAIN ENTRENCHED ACROSS THE WESTERN GREAT LAKES THROUGH TODAY BEFORE GRADUALLY WARMING AND RETREATING DURING THE UPCOMING WEEKEND. LAKE EFFECT SNOW SHOWERS WILL ALSO CONTINUE WITHIN THE COLD AIR MASS THROUGH THIS AFTERNOON. ANOTHER ALBERTA CLIPPER TYPE LOW PRESSURE SYSTEM WILL TRACK THROUGH THE WESTERN GREAT LAKES SATURDAY AND SATURDAY NIGHT WHICH WILL BRING A PROLONGED PERIOD OF ACCUMULATING SNOWFALL TO MUCH OF NORTHERN MICHIGAN. && .SHORT TERM.../ISSUED AT 345 AM/...TODAY A DEEP TROF ACROSS THE EASTERN CONUS IS CONTINUING TO KEEP BITTERLY COLD CONDITIONS ENTRENCHED ACROSS THE GREAT LAKES REGION THIS MORNING. ALREADY WATCHING THE NEXT UPPER LEVEL WAVE TO IMPACT THE REGION STARTING TO DROP SOUTHWARD ACROSS SASKATCHEWAN. AS ANTICIPATED...LAKE EFFECT SNOW BANDS ARE CONTINUING TO IMPACT THE SNOWBELTS IN NORTHWEST LOWER AND EASTERN UPPER MICHIGAN AND IS THE MAIN SHORT TERM CONCERN ALONG WITH THE DANGEROUSLY LOW WIND CHILL VALUES. NORTHWEST FLOW LAKE EFFECT CONTINUES TO DOMINATE THIS MORNING AND THE LATEST RUC AND NAM MODEL RUNS EACH SUGGEST THAT THE WIND DIRECTION SHOULD CONTINUE TO TARGET THESE AREAS INTO THE MID TO LATE MORNING HOURS. THUS...CONSIDERING THE POOR CONDITIONS STILL OBSERVED ACROSS THE WARNING AND ADVISORY AREAS...WE WILL GO AHEAD AND EXTEND THE HEADLINES THROUGH THE MORNING HOURS WITH ANOTHER 1 TO 3 INCHES OF SNOW POSSIBLE. ACROSS EASTERN UPPER MICHIGAN...WE HAVE BEGUN TO SEE THE DRAINAGE FLOW PUSHING EVERYTHING FARTHER WEST. THIS TREND SHOULD CONTINUE THROUGH THE EARLY MORNING HOURS...THEN BEGIN TO PUSH BACK TO THE EAST AS THE DRAINAGE FLOW CEASES BY LATE MORNING. ANOTHER 2 TO 4 INCHES OF SNOW MAY BE POSSIBLE AROUND PARADISE AND WHITEFISH POINT. GOING TO EXTEND THE ADVISORY IN EASTERN UPPER THROUGH THIS EVENING AS SNOW SHOWERS WILL LIKELY PERSIST THROUGH THE AFTERNOON HOURS. EVENTUALLY...THE LARGE SCALE SURFACE WINDS WILL BACK AROUND THE WEST...THEN SOUTHWEST AS THE SHORT WAVE RIDGE AXIS PUSHES INTO THE WESTERN GREAT LAKES. ALTHOUGH ANTICYCLONIC FLOW AND LOWERING INVERSION HEIGHTS MAY START TO HINDER LES THIS AFTERNOON...DO NOT WANT TO UNDERESTIMATE THE INSTABILITY THAT REMAINS AND WILL KEEP SNOW SHOWERS IN THE FORECAST THROUGH THE AFTERNOON AND EVENING HOURS. AS FOR TEMPERATURES...SINGLE DIGITS TO LOW TEENS STILL LOOK REASONABLE. WE WILL EXTEND THE WIND CHILL ADVISORY TO MAINLY COVER THE MORNING HOURS AS TEMPERATURE WILL EVENTUALLY WARM ENOUGH BY EARLY AFTERNOON TO KEEP WIND CHILL VALUES OUT OF ADVISORY THRESHOLDS. KAS && .LONG TERM.../ISSUED AT 345 AM/...TONIGHT AND BEYOND FINALLY...THE BITTERLY COLD AIR LOOKS LIKE IT IS ON THE WAY OUT AS WE HEAD INTO THE UPCOMING WEEKEND. HOWEVER...THE WAVE OVER SASKATCHEWAN WILL TAKE AIM ON THE AREA ON SATURDAY WITH THE BEST MOISTURE AND FORCING REMAINING ALONG AND SOUTH OF M-72. MODELS ARE IN FAIRLY DECENT AGREEMENT WITH RESPECT TO PLACEMENT AND TIMING OF THIS SYSTEM...SO WILL BUMP UP POPS TO CATEGORICAL ACROSS THE SOUTH FROM SATURDAY INTO SATURDAY NIGHT. LOOKS LIKE WE MAY GET SOME LAKE ENHANCEMENT EARLY ON SATURDAY MORNING ALONG THE SOUTHERN SHORES OF MACKINAC COUNTY AS SOUTHERLY WINDS DEVELOP AHEAD OF THE WAVE. THE WINDS WILL GRADUALLY BACK THROUGH THE DAY...EVENTUALLY SHIFTING THE FOCUS TO LAKE HURON ENHANCEMENT. AS IT APPEARS NOW...THE LAKE HURON ENHANCEMENT DOES NOT APPEAR TO BE TOO BIG OF A CONCERN WITH THE BETTER MOISTURE AXIS SLIDING THROUGH CENTRAL AND SOUTHERN LOWER MICHIGAN. HOWEVER...WE ARE STILL LIKELY TO SEE SOME UPTICK IN SNOWFALL INTENSITIES IN THESE AREAS...BUT FEEL THAT WARNING CRITERIA SNOWS WILL BE HARD TO COME BY. THUS...FOLLOWING THE DAYSHIFT THOUGHTS...GOING TO HOLD OFF ON ANY WATCH. FORECAST QUIETS DOWN CONSIDERABLY BY SUNDAY AS WE WAIT THE ARRIVAL OF OUR NEXT SYSTEM FOR SUNDAY NIGHT. LEFT SOME RESIDUAL FLURRIES IN THE FORECAST FOR SUNDAY AS WE DO KEEP SOME WEAK SYNOPTIC SUPPORT/MOISTURE AROUND THROUGH THE DAY. HOWEVER...MEASURABLE SNOWFALL WILL NOT BE LIKELY IN MOST SPOTS. NO CHANGES MADE BEYOND SUNDAY...ALTHOUGH WE WILL CONTINUE TO SEE A SERIES OF CLIPPER SYSTEMS DROPPING SOUTHEAST THROUGH THE AREA THROUGH THE UPCOMING WEEK AND PERHAPS BEYOND. AFTER A WEEK OF SEASONABLE TEMPERATURES...ANOTHER SHOT OF COLDER (PERHAPS NOT AS COLD AS RECENTLY) AIR WILL ARRIVE LATE IN THE WEEK. KAS && .MARINE.../ISSUED AT 345 AM/ WITH COLD AIR STILL ENTRENCHED ACROSS THE GREAT LAKES...UNSTABLE CONDITIONS CONTINUE TO BE PRESENT OVER THE NEARSHORE WATERS. THUS...SMALL CRAFT ADVISORIES WILL CONTINUE ON LAKE MICHIGAN THROUGH TONIGHT FOR BOTH WAVES AND WINDS. KAS && .AVIATION.../ISSUED AT 632 AM/...VALID FOR 12Z TAFS LAKE EFFECT REGIME EXPECTED TO CONTINUE THROUGH THIS AFTERNOON...BRINGING LOW END VFR/HIGH END MVFR CONDITIONS TO ALL TAF SITES. STILL THINKING THE GREATER EMPHASIS FOR ADDITIONAL SNOW SHOWERS AND LOWER CLOUD CEILINGS WILL BE FOUND AT KPLN AND KTVC. KAS && .APX WATCHES/WARNINGS/ADVISORIES... MI...WIND CHILL ADVISORY UNTIL NOON EST TODAY FOR MIZ015>018-023-024- 029-030-033>036-041-042. LAKE EFFECT SNOW ADVISORY UNTIL NOON EST TODAY FOR MIZ019-020- 022-025-026-028-031-032. LAKE EFFECT SNOW WARNING UNTIL NOON EST TODAY FOR MIZ021-027. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ008. LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST SATURDAY FOR LMZ323-342- 344>346. HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR LMZ342-344>346. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 117 AM EST FRI JAN 16 2009 UPDATED FOR 06Z AVIATION DISCUSSION .UPDATE... RADAR INDICATED A GRADUAL SHIFT OF THE MULTIPLE WIND PARALLEL LES BANDS BUT STILL ALIGNED WITH 300-310 FLOW. WITH SLOW BACKING TREND OVERNIGHT...EXPECT LES TO PERSIST FROM KP53 EASTWARD. GOING FCST SNOW AMOUNTS IN THE 1 TO 4 INCH STILL LOOK REASONABLE. OVER THE WEST...VSBY WAS ALSO LOW AT TIMES WITH FINE GRAINED SNOW IN THE ARCTIC AIRMASS. WITH LIMITED SNOWGROWTH...ADDITIONAL ACCUMULATIONS OF ONLY AN INCH OR TWO ARE EXPECTED. LAND BREEZE DEVELOPMENT AND A TIGHTER GRADIENT BTWN LAKE INDUCED AROUND THE PERIPHERY OF THE LAKE INDUCED TROUGH WILL RESULT IN A GREATER WRLY FLOW OF UNMODIFIED ARCTIC AIR ACROSS N CNTRL UPPER MI. SO WITH TEMPS INTO THE -8 F TO -15 RANGE AND WINDS OF 5 TO 15 MPH...WIND CHILL VALUES INTO THE 25 BELOW TO 40 BELOW RANGE STILL SEEMS ON TRACK. FARTHER INLAND...FROM KIWD TO KIMT...WINDS MAY BE LIGHTER...5 TO 10 MPH BUT WILL ALLOW TEMPS TO FALL OFF FURTHER...CLOSER TO -20F. .SYNOPSIS... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW AN AMPLIFIED PATTERN ACROSS NAMERICA WITH PRONOUNCED RIDGE OVER THE W AND A DEEP TROF OVER THE E. ARCTIC AIRMASS IS WELL ENTRENCHED FROM THE UPPER MISSISSIPPI VALLEY EWD. 12Z RAOBS INDICATED 850MB TEMPS OF -25C OR LWR FROM MN E TO NRN NEW ENGLAND AND N TO HUDSON BAY. TYPICAL PURE LES PATTERN IS UNDERWAY ACROSS THE UPPER LAKES. COLD AIR IS LEADING TO SMALL FLAKE SIZE THAT IS EXTREMELY EFFECTIVE AT REDUCING VIS... BUT DOES NOT ACCUMULATE SIGNIFICANTLY. IF DRIVING...IT CAN BE A WHITEOUT AROUND OTHER VEHICLES KICKING UP THE DRY SNOW. SFC OBS SUGGEST A MESOLOW LOCATED JUST W OR NW OF WHITEFISH PT...AND MONTREAL RIVER RADAR SHOWS A WIDE BAND OF SNOW JUST N AND W OF WHITEFISH PT WHERE STRONG CONVERGENCE IS OCCURRING. AWAY FROM THE LES...DRY AIRMASS HAS LED TO MOSTLY SUNNY SKIES THOUGH THERE HAS BEEN SOME DIURNAL STRATOCU DEVELOPMENT INLAND. TEMPS THIS AFTN HAVE FAILED TO RISE ABOVE 0F OVER MUCH OF THE NW HALF OF THE FCST AREA DESPITE SUN. && .SHORT TERM (TONIGHT/FRI)... LITTLE CHANGE WILL OCCUR IN THE PATTERN TONIGHT. LOW-LEVEL WINDS WILL BACK A BIT AS LARGE HIGH PRES OVER THE CNTRL PLAINS DRIFTS E. SO...THERE SHOULD BE A SLIGHT N SHIFT OF THE SRN EDGE OF LES OVER WRN UPPER MI THRU THE NIGHT...AND BACK EDGE OF LES TO THE E SHOULD GRADUALLY SHIFT E ACROSS ALGER COUNTY. HIGH RES MODELS SUGGEST NW TO N FLOW ACROSS LAKE SUPERIOR WILL SHIFT MESOLOW OVER FAR SE LAKE SUPERIOR TO THE SE FOR A TIME TONIGHT BEFORE STRENGTHENING LAND BREEZES OWING TO SHARP TEMP DROP OVER LAND CAUSES REDEVELOPMENT BACK TO THE NW OVER THE LAKE. SO...HEAVIEST SNOW TONIGHT WILL LIKELY FALL ROUGHLY FROM THE GRAND MARAIS AREA ACROSS NRN LUCE COUNTY DUE TO FOCUSED CONVERGENCE. STILL...GIVEN HOW COLD THE AIRMASS IS...IT WILL BE DIFFICULT TO GET DENDRITES TO FORM...SO SNOW-TO-WATER RATIOS WILL CONTINUE TO BE LOWER THAN USUAL FOR LES. MAY SEE LOCALIZED ACCUMULATIONS UPWARDS OF 4 INCHES IN PLACES THAT REMAIN UNDER DOMINANT BANDS THE LONGEST. LES ADVY WILL REMAIN UP FOR ALGER/NRN SCHOOLCRAFT/LUCE...MAINLY DUE TO THE EXTREMELY POOR VIS WITH THIS TYPE OF ARCTIC AIR LES. OTHERWISE...DON`T EXPECT MORE THAN 1-2 INCHES IN THE LES AREAS TONIGHT. AS FOR TEMPS...ALTHOUGH CENTER OF SFC HIGH PRES WILL BE PASSING WELL S OF HERE...WINDS MAY DECOUPLE MORE THAN WHAT MODELS SUGGEST AWAY FROM LAKE SUPERIOR. HAVE LOWERED MINS FROM INHERITED FCST AND UNDERCUT THE LOWEST MOS GUIDANCE BY 3-8 DEGREES. MINS OF -20 TO -25F SHOULD BE FAIRLY COMMON FROM WRN MARQUETTE COUNTY TO CRYSTAL FALLS AND KIWD. IF WINDS DIMINISH MORE THAN EXPECTED...TEMPS MAY PLUMMET TO -30F IN THE TYPICAL COLD SPOTS. BASED ON FCST WINDS/TEMPS...GOING WIND CHILL HEADLINES TONIGHT THRU FRI MORNING APPEAR ON TRACK. WAA WILL BE UNDERWAY FRI WITH A CONTINUED SLOW BACKING OF WINDS. SO BACK EDGE OF LES WILL CONTINUE TO SHIFT GRADUALLY N OVER THE WRN U.P. AND GRADUALLY E TO THE E OF MUNISING. ACCUMULATIONS AGAIN SHOULD BE IN THE 1 TO LOCALLY 4 INCH RANGE WITH THE HIGHER AMOUNTS E OF GRAND MARAIS. SHOULD BE A FAIR AMOUNT OF SUN AWAY FROM LES...AND WITH WAA...TEMPS SHOULD TOP OUT IN THE SINGLE DIGITS ABOVE ZERO EVERYWHERE. .LONG TERM (FRIDAY NIGHT THROUGH NEXT THURSDAY)... POSITIVE PNA PATTERN PERSISTS WITH RIDGE ALONG WRN NOAM AND TROUGH OVR MUCH OF ERN NOAM INTO GREENLAND. EVENTUALLY...TROUGH UPSTREAM OVR PACIFIC EDGES EAST WHICH BUCKLES THE PATTERN DOWNSTREAM INTO THE CONUS. SLIGHT WIGGLE IN THE PATTERN ALLOWS HEIGHTS TO GRADUALLY BUILD OVR NRN PLAINS INTO WRN PERIPHERY OF GREAT LAKES. RESULT IS A NOTABLE WARMING TREND BY EARLY NEXT WEEK BEFORE ANOTHER SURGE OF COLD AIR COMES SOUTH INTO THE UPR LAKES LATE NEXT WEEK. CLIPPER LOW PRESSURE SYSTEM COULD BRING SOME WIDESPREAD SNOW ON SAT. OTHERWISE...LK EFFECT SNOW CONTINUES IN NW/N FLOW AREAS THROUGH NEXT TUE. FOLLOWED A TRACK TO THE SAT CLIPPER BTWN THE FARTHER WEST NAM AND REGIONAL CANADIAN AND THE FARTHER EAST GFS/ECMWF. A BIT LEARY OF GOING WITH ANY SOLUTION ON THE FAR EAST SIDE OF GUIDANCE AS LOW PRESSURE SYSTEMS THE LAST WEEK ENDED UP DIGGING FARTHER SOUTH THAN GUIDANCE INDICATED. EVEN SO...A NAM/GFS/ECMWF BLEND BRINGS SHORTWAVE AND SWATH OF DEEPER MOISTURE THROUGH MOST OF UPR MI LATE FRI EVENING INTO SAT. LOWEST CONDENSATION PRES DEFICITS ON THE 280K ISENTROPIC SFC MORE OVR CNTRL WI WITH AVG MIXING RATIOS TOWARD UPR MI BORDER 1.5-2.0 G/KG WHICH SUPPORTS 3-4 INCHES OF SNOW IN 12 HR. THIS JIVES WELL WITH EXPECTED QPF AMOUNTS UP TO 0.25 INCH. ALSO...SW/S H95-H85 WINDS OVR NRN LK MICHIGAN INTO SRN SCHOOLCRAFT FM 06Z SAT THROUGH 18Z SAT (BASICALLY DURING THE MAXIMUM SYNOPTIC SUPPORT) WITH SUFFICIENT LAKE INDUCED INSTABILITY COULD ENHANCE THE SNOW. DEEP FAVORABLE SNOW GROWTH ZONE (TO 200 MB THICK) ON THE NRN LK MI SOUNDING FM BOTH GFS/NAM WILL LEAD TO HIGHER SNOW-WATER RATIOS. MAIN NEGATIVE FACTOR FOR SIGNIFICANT HEAVY SNOW IS STEADILY VEERING LOW LEVEL WINDS FM SW TO SE. NOTABLE SHEAR IS ALSO PRESENT IN LOWEST LEVELS. MADE A SIGNIFICANT UPWARD ADJUSTMENT TO POPS IN THE FRI NIGHT AND SAT TIME FRAME. ADVY LEVEL SNOWS ARE CERTAINLY POSSIBLE...ESPECIALLY CLOSER TO LK MICHIGAN WITH ONSHORE FLOW. WILL ALSO HAVE TO WATCH THE LK EFFECT FOR SAT NIGHT INTO SUN AM. SFC TROUGH POKING UP FM DEPARTING SFC LOW. THIS SYNOPTIC BOUNDARY MAY ENHANCE LOW-LEVEL CONVERGENCE EVEN AS GRADIENT WINDS LIGHTEN. MESOSCALE EFFECTS WILL LIKELY DOMINATE WHERE BEST LAKE EFFECT DEVELOPS. SOUNDINGS SHOW THE DEEPER SNOW GROWTH LAYER HANGING ON INTO SUN. SO...WHERE THE SNOW OCCURS SNOW RATIOS STAY ON THE HIGH SIDE RESULTING IN POTENTIAL LOCALIZED...BUT MODERATE ACCUMS. MORE TRADITIONAL NW FLOW LAKE EFFECT SHOULD DEVELOP INTO SUN AS SYNOPTIC TROUGH SHIFTS EAST. LOWERING INVERSIONS AND DECREASING MOISTURE IN THE LK EFFECT LAYER DIMINISHES THE SNOW. BOTH GFS/ECMWF NOW INDICATE NEXT CLIPPER DROPS WELL TO THE SOUTH OF UPR LAKES SUN NIGHT INTO MON. SYNOPTIC SNOW CHANCES SEEM TO BE MINIMAL. KEPT SOME LOW POPS IN THROUGH TUE...BUT BEST SNOW CHANCES ARE IN THE LK EFFECT SNOW AREAS OF THE NRN CWA. FINALLY...AS MENTIONED EARLIER THERE REMAINS A SIGNAL FOR A MORE NOTABLE WARMUP FOR MIDDLE OF NEXT WEEK. GFS/ECMWF INDICATE AN H85 TEMP PATTERN ALSO SHOWN BY GFS ENS AND NAEFS. MIXING TO H85 WITH LACK OF STRONG WINDS IS VERY UNLIKELY...BUT STILL MIXING TO H9 TEMPS EXPECTED YIELDS LWR 30S WHICH WAS CLOSE TO GOING HPC GUIDANCE. COULD EVEN SEE TEMPS WELL INTO THE 30S IF ENOUGH SUNSHINE IS REALIZED. AS ALWAYS...COULD BE SOME LGT PCPN WITH THE WARM AIR ADVECTION. PROGS LOOKED QUITE DRY THOUGH AS SOURCE AIRMASS IS OFF THE NRN ROCKIES AND NRN PLAINS. KEPT THE POPS OUT AS A RESULT. GFS AND LATEST ECMWF ARE INSISTENT THAT COLD AIR RUSHES BACK IN LATE NEXT THU INTO FRI. H85 TEMPS HEAD BACK TOWARD -25C BY 12Z FRIDAY. SO...IT APPEARS THAT THE WARM UP NEXT WEEK WILL ONLY BE BRIEF. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... AT KCMX...WITH NW FLOW OF VERY COLD ARCTIC AIR CONTINUING THROUGH FRI MORNING...LES WILL CONTINUE. PERSISTENCE FCST APPEARS THE WAY TO GO AS LITTLE OVERALL CHANGE IN AIRMASS WILL OCCUR THRU FRI MORNING. EXPECT IFR/LIFR CONDITIONS TO PREVAIL AT KCMX. AS A RIDGE BUILDS TOWARD THE WESTERN GREAT LAKES AND WINDS BACK TO WSW FRI AFTERNOON...THE MORE SIGNIFICANT LES BANDS WILL SHIFT NORTH OF KCMX WITH VFR CONDITIONS EXPECTED TOWARD EVENING. AT KSAW...DOWNSLOPING COMPONENT WITH WNW WIND WILL RESULT IN VFR CONDITIONS PREVAILING THRU THIS FCST PERIOD. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... THERE WILL BE A FEW GALE FORCE GUSTS OVER PORTIONS OF SCNTRL LAKE SUPERIOR TONIGHT IN TIGHTER GRADIENT CAUSED BY MESOLOW NEAR WHITEFISH PT. OTHERWISE...NO GALE FORCE WINDS ARE EXPECTED DURING THIS FCST PERIOD. HEAVY FREEZING SPRAY WILL CONTINUE TONIGHT/FRI UNDER ARCTIC AIRMASS/BLUSTERY CONDITIONS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WIND CHILL ADVISORY UNTIL 10 AM EST /9 AM CST/ FRIDAY FOR MIZ001- 003-006-007-012>014-085. WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR MIZ002- 004-005-009>011-084. LAKE EFFECT SNOW ADVISORY UNTIL 4 PM EST FRIDAY FOR MIZ006-007- 085. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST FRIDAY FOR LSZ263>267. HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR LSZ162. && $$ SYNOPSIS...ROLFSON SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...JLB MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1045 PM EST THU JAN 15 2009 .UPDATE... RADAR INDICATED A GRADUAL SHIFT OF THE MULTIPLE WIND PARALLEL LES BANDS BUT STILL ALIGNED WITH 300-310 FLOW. WITH SLOW BACKING TREND OVERNIGHT...EXPECT LES TO PERSIST FROM KP53 EASTWARD. GOING FCST SNOW AMOUNTS IN THE 1 TO 4 INCH STILL LOOK REASONABLE. OVER THE WEST...VSBY WAS ALSO LOW AT TIMES WITH FINE GRAINED SNOW IN THE ARCTIC AIRMASS. WITH LIMITED SNOWGROWTH...ADDITIONAL ACCUMULATIONS OF ONLY AN INCH OR TWO ARE EXPECTED. LAND BREEZE DEVELOPMENT AND A TIGHTER GRADIENT BTWN LAKE INDUCED AROUND THE PERIPHERY OF THE LAKE INDUCED TROUGH WILL RESULT IN A GREATER WRLY FLOW OF UNMODIFIED ARCTIC AIR ACROSS N CNTRL UPPER MI. SO WITH TEMPS INTO THE -8 F TO -15 RANGE AND WINDS OF 5 TO 15 MPH...WIND CHILL VALUES INTO THE 25 BELOW TO 40 BELOW RANGE STILL SEEMS ON TRACK. FARTHER INLAND...FROM KIWD TO KIMT...WINDS MAY BE LIGHTER...5 TO 10 MPH BUT WILL ALLOW TEMPS TO FALL OFF FURTHER...CLOSER TO -20F. .SYNOPSIS... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW AN AMPLIFIED PATTERN ACROSS NAMERICA WITH PRONOUNCED RIDGE OVER THE W AND A DEEP TROF OVER THE E. ARCTIC AIRMASS IS WELL ENTRENCHED FROM THE UPPER MISSISSIPPI VALLEY EWD. 12Z RAOBS INDICATED 850MB TEMPS OF -25C OR LWR FROM MN E TO NRN NEW ENGLAND AND N TO HUDSON BAY. TYPICAL PURE LES PATTERN IS UNDERWAY ACROSS THE UPPER LAKES. COLD AIR IS LEADING TO SMALL FLAKE SIZE THAT IS EXTREMELY EFFECTIVE AT REDUCING VIS... BUT DOES NOT ACCUMULATE SIGNIFICANTLY. IF DRIVING...IT CAN BE A WHITEOUT AROUND OTHER VEHICLES KICKING UP THE DRY SNOW. SFC OBS SUGGEST A MESOLOW LOCATED JUST W OR NW OF WHITEFISH PT...AND MONTREAL RIVER RADAR SHOWS A WIDE BAND OF SNOW JUST N AND W OF WHITEFISH PT WHERE STRONG CONVERGENCE IS OCCURRING. AWAY FROM THE LES...DRY AIRMASS HAS LED TO MOSTLY SUNNY SKIES THOUGH THERE HAS BEEN SOME DIURNAL STRATOCU DEVELOPMENT INLAND. TEMPS THIS AFTN HAVE FAILED TO RISE ABOVE 0F OVER MUCH OF THE NW HALF OF THE FCST AREA DESPITE SUN. && .SHORT TERM (TONIGHT/FRI)... LITTLE CHANGE WILL OCCUR IN THE PATTERN TONIGHT. LOW-LEVEL WINDS WILL BACK A BIT AS LARGE HIGH PRES OVER THE CNTRL PLAINS DRIFTS E. SO...THERE SHOULD BE A SLIGHT N SHIFT OF THE SRN EDGE OF LES OVER WRN UPPER MI THRU THE NIGHT...AND BACK EDGE OF LES TO THE E SHOULD GRADUALLY SHIFT E ACROSS ALGER COUNTY. HIGH RES MODELS SUGGEST NW TO N FLOW ACROSS LAKE SUPERIOR WILL SHIFT MESOLOW OVER FAR SE LAKE SUPERIOR TO THE SE FOR A TIME TONIGHT BEFORE STRENGTHENING LAND BREEZES OWING TO SHARP TEMP DROP OVER LAND CAUSES REDEVELOPMENT BACK TO THE NW OVER THE LAKE. SO...HEAVIEST SNOW TONIGHT WILL LIKELY FALL ROUGHLY FROM THE GRAND MARAIS AREA ACROSS NRN LUCE COUNTY DUE TO FOCUSED CONVERGENCE. STILL...GIVEN HOW COLD THE AIRMASS IS...IT WILL BE DIFFICULT TO GET DENDRITES TO FORM...SO SNOW-TO-WATER RATIOS WILL CONTINUE TO BE LOWER THAN USUAL FOR LES. MAY SEE LOCALIZED ACCUMULATIONS UPWARDS OF 4 INCHES IN PLACES THAT REMAIN UNDER DOMINANT BANDS THE LONGEST. LES ADVY WILL REMAIN UP FOR ALGER/NRN SCHOOLCRAFT/LUCE...MAINLY DUE TO THE EXTREMELY POOR VIS WITH THIS TYPE OF ARCTIC AIR LES. OTHERWISE...DON`T EXPECT MORE THAN 1-2 INCHES IN THE LES AREAS TONIGHT. AS FOR TEMPS...ALTHOUGH CENTER OF SFC HIGH PRES WILL BE PASSING WELL S OF HERE...WINDS MAY DECOUPLE MORE THAN WHAT MODELS SUGGEST AWAY FROM LAKE SUPERIOR. HAVE LOWERED MINS FROM INHERITED FCST AND UNDERCUT THE LOWEST MOS GUIDANCE BY 3-8 DEGREES. MINS OF -20 TO -25F SHOULD BE FAIRLY COMMON FROM WRN MARQUETTE COUNTY TO CRYSTAL FALLS AND KIWD. IF WINDS DIMINISH MORE THAN EXPECTED...TEMPS MAY PLUMMET TO -30F IN THE TYPICAL COLD SPOTS. BASED ON FCST WINDS/TEMPS...GOING WIND CHILL HEADLINES TONIGHT THRU FRI MORNING APPEAR ON TRACK. WAA WILL BE UNDERWAY FRI WITH A CONTINUED SLOW BACKING OF WINDS. SO BACK EDGE OF LES WILL CONTINUE TO SHIFT GRADUALLY N OVER THE WRN U.P. AND GRADUALLY E TO THE E OF MUNISING. ACCUMULATIONS AGAIN SHOULD BE IN THE 1 TO LOCALLY 4 INCH RANGE WITH THE HIGHER AMOUNTS E OF GRAND MARAIS. SHOULD BE A FAIR AMOUNT OF SUN AWAY FROM LES...AND WITH WAA...TEMPS SHOULD TOP OUT IN THE SINGLE DIGITS ABOVE ZERO EVERYWHERE. .LONG TERM (FRIDAY NIGHT THROUGH NEXT THURSDAY)... POSITIVE PNA PATTERN PERSISTS WITH RIDGE ALONG WRN NOAM AND TROUGH OVR MUCH OF ERN NOAM INTO GREENLAND. EVENTUALLY...TROUGH UPSTREAM OVR PACIFIC EDGES EAST WHICH BUCKLES THE PATTERN DOWNSTREAM INTO THE CONUS. SLIGHT WIGGLE IN THE PATTERN ALLOWS HEIGHTS TO GRADUALLY BUILD OVR NRN PLAINS INTO WRN PERIPHERY OF GREAT LAKES. RESULT IS A NOTABLE WARMING TREND BY EARLY NEXT WEEK BEFORE ANOTHER SURGE OF COLD AIR COMES SOUTH INTO THE UPR LAKES LATE NEXT WEEK. CLIPPER LOW PRESSURE SYSTEM COULD BRING SOME WIDESPREAD SNOW ON SAT. OTHERWISE...LK EFFECT SNOW CONTINUES IN NW/N FLOW AREAS THROUGH NEXT TUE. FOLLOWED A TRACK TO THE SAT CLIPPER BTWN THE FARTHER WEST NAM AND REGIONAL CANADIAN AND THE FARTHER EAST GFS/ECMWF. A BIT LEARY OF GOING WITH ANY SOLUTION ON THE FAR EAST SIDE OF GUIDANCE AS LOW PRESSURE SYSTEMS THE LAST WEEK ENDED UP DIGGING FARTHER SOUTH THAN GUIDANCE INDICATED. EVEN SO...A NAM/GFS/ECMWF BLEND BRINGS SHORTWAVE AND SWATH OF DEEPER MOISTURE THROUGH MOST OF UPR MI LATE FRI EVENING INTO SAT. LOWEST CONDENSATION PRES DEFICITS ON THE 280K ISENTROPIC SFC MORE OVR CNTRL WI WITH AVG MIXING RATIOS TOWARD UPR MI BORDER 1.5-2.0 G/KG WHICH SUPPORTS 3-4 INCHES OF SNOW IN 12 HR. THIS JIVES WELL WITH EXPECTED QPF AMOUNTS UP TO 0.25 INCH. ALSO...SW/S H95-H85 WINDS OVR NRN LK MICHIGAN INTO SRN SCHOOLCRAFT FM 06Z SAT THROUGH 18Z SAT (BASICALLY DURING THE MAXIMUM SYNOPTIC SUPPORT) WITH SUFFICIENT LAKE INDUCED INSTABILITY COULD ENHANCE THE SNOW. DEEP FAVORABLE SNOW GROWTH ZONE (TO 200 MB THICK) ON THE NRN LK MI SOUNDING FM BOTH GFS/NAM WILL LEAD TO HIGHER SNOW-WATER RATIOS. MAIN NEGATIVE FACTOR FOR SIGNIFICANT HEAVY SNOW IS STEADILY VEERING LOW LEVEL WINDS FM SW TO SE. NOTABLE SHEAR IS ALSO PRESENT IN LOWEST LEVELS. MADE A SIGNIFICANT UPWARD ADJUSTMENT TO POPS IN THE FRI NIGHT AND SAT TIME FRAME. ADVY LEVEL SNOWS ARE CERTAINLY POSSIBLE...ESPECIALLY CLOSER TO LK MICHIGAN WITH ONSHORE FLOW. WILL ALSO HAVE TO WATCH THE LK EFFECT FOR SAT NIGHT INTO SUN AM. SFC TROUGH POKING UP FM DEPARTING SFC LOW. THIS SYNOPTIC BOUNDARY MAY ENHANCE LOW-LEVEL CONVERGENCE EVEN AS GRADIENT WINDS LIGHTEN. MESOSCALE EFFECTS WILL LIKELY DOMINATE WHERE BEST LAKE EFFECT DEVELOPS. SOUNDINGS SHOW THE DEEPER SNOW GROWTH LAYER HANGING ON INTO SUN. SO...WHERE THE SNOW OCCURS SNOW RATIOS STAY ON THE HIGH SIDE RESULTING IN POTENTIAL LOCALIZED...BUT MODERATE ACCUMS. MORE TRADITIONAL NW FLOW LAKE EFFECT SHOULD DEVELOP INTO SUN AS SYNOPTIC TROUGH SHIFTS EAST. LOWERING INVERSIONS AND DECREASING MOISTURE IN THE LK EFFECT LAYER DIMINISHES THE SNOW. BOTH GFS/ECMWF NOW INDICATE NEXT CLIPPER DROPS WELL TO THE SOUTH OF UPR LAKES SUN NIGHT INTO MON. SYNOPTIC SNOW CHANCES SEEM TO BE MINIMAL. KEPT SOME LOW POPS IN THROUGH TUE...BUT BEST SNOW CHANCES ARE IN THE LK EFFECT SNOW AREAS OF THE NRN CWA. FINALLY...AS MENTIONED EARLIER THERE REMAINS A SIGNAL FOR A MORE NOTABLE WARMUP FOR MIDDLE OF NEXT WEEK. GFS/ECMWF INDICATE AN H85 TEMP PATTERN ALSO SHOWN BY GFS ENS AND NAEFS. MIXING TO H85 WITH LACK OF STRONG WINDS IS VERY UNLIKELY...BUT STILL MIXING TO H9 TEMPS EXPECTED YIELDS LWR 30S WHICH WAS CLOSE TO GOING HPC GUIDANCE. COULD EVEN SEE TEMPS WELL INTO THE 30S IF ENOUGH SUNSHINE IS REALIZED. AS ALWAYS...COULD BE SOME LGT PCPN WITH THE WARM AIR ADVECTION. PROGS LOOKED QUITE DRY THOUGH AS SOURCE AIRMASS IS OFF THE NRN ROCKIES AND NRN PLAINS. KEPT THE POPS OUT AS A RESULT. GFS AND LATEST ECMWF ARE INSISTENT THAT COLD AIR RUSHES BACK IN LATE NEXT THU INTO FRI. H85 TEMPS HEAD BACK TOWARD -25C BY 12Z FRIDAY. SO...IT APPEARS THAT THE WARM UP NEXT WEEK WILL ONLY BE BRIEF. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... AT KCMX...WITH NW FLOW OF VERY COLD ARCTIC AIR CONTINUING DURING THIS FCST PERIOD...LES WILL CONTINUE. PERSISTENCE FCST APPEARS THE WAY TO GO AS LITTLE OVERALL CHANGE IN AIRMASS WILL OCCUR THRU FRI MORNING. EXPECT IFR/LIFR CONDITIONS TO PREVAIL AT KCMX. AS A RIDGE BUILDS TOWARD THE WESTERN GREAT LAKES AND WINDS BACK TO WSW FRI AFTERNOON...THE MORE SIGNIFICANT LES BANDS WILL SHIFT NORTH OF KCMX. AT KSAW...DOWNSLOPING COMPONENT WITH WNW WIND WILL RESULT IN VFR CONDITIONS PREVAILING THRU THIS FCST PERIOD. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... THERE WILL BE A FEW GALE FORCE GUSTS OVER PORTIONS OF SCNTRL LAKE SUPERIOR TONIGHT IN TIGHTER GRADIENT CAUSED BY MESOLOW NEAR WHITEFISH PT. OTHERWISE...NO GALE FORCE WINDS ARE EXPECTED DURING THIS FCST PERIOD. HEAVY FREEZING SPRAY WILL CONTINUE TONIGHT/FRI UNDER ARCTIC AIRMASS/BLUSTERY CONDITIONS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WIND CHILL ADVISORY UNTIL 10 AM EST /9 AM CST/ FRIDAY FOR MIZ001- 003-006-007-012>014-085. WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR MIZ002- 004-005-009>011-084. LAKE EFFECT SNOW ADVISORY UNTIL 4 PM EST FRIDAY FOR MIZ006-007- 085. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST FRIDAY FOR LSZ263>267. HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR LSZ162. && $$ SYNOPSIS...ROLFSON SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 655 PM EST THU JAN 15 2009 .SYNOPSIS.../ISSUED AT 350 PM/ ARCTIC AIR WILL REMAIN ENTRENCHED ACROSS THE WESTERN GREAT LAKES THROUGH FRIDAY BEFORE GRADUALLY WARMING AND RETREATING DURING THE UPCOMING WEEKEND. LAKE EFFECT SNOW SHOWERS WILL ALSO CONTINUE WITHIN THE COLD AIR MASS. ANOTHER ALBERTA CLIPPER TYPE LOW PRESSURE SYSTEM WILL TRACK THROUGH THE WESTERN GREAT LAKES SATURDAY AND SUNDAY WHICH MAY BRING A PROLONGED PERIOD OF ACCUMULATING SNOWFALL TO MUCH OF NORTHERN MICHIGAN THIS WEEKEND. ADAM && .SHORT TERM.../ISSUED AT 350 PM/...TONIGHT 2 CONCERNS TONIGHT. FIRST THE WIND CHILLS. WITH THE TEMPERATURES PRIMARILY IN THE SINGLE DIGITS ACROSS MOST OF NORTHERN MICHIGAN, AND WITH THE WINDS GETTING TO 10 MPH OVERNIGHT, WE WILL SEE SOME LOCATIONS GETTING INTO THE -20F TO -25F RANGE IN N LOWER AND COLDER THAN -25F IN E UPPER. OTHERWISE, THE BIG CONCERN IS THE PERPETUAL LES NW BANDS THAT ARE IN THE REGION NOW. THERE HAVE BEEN SOME DECENT CONVERGENCE OF A FEW BANDS THROUGHOUT THE DAY THAT HAVE BROUGHT SOME INCH AN HOUR RATES, MAINLY IN ANTRIM AND KALKASKA COUNTIES. WITH THAT IN MIND THE GFS, NAM, AND RUC ALL AGREE THAT THE NW FLOW CONTINUES THROUGH THE NIGHT IN NW LOWER. SO WOULD EXPECT THAT THE SAME TREND OF CONVERGING BANDS WILL CONTINUE. IN E UPPER THE BANDS MOVED TO THE EAST SLOWLY OVER THE DAY, NOT REACHING THE WESTERN END OF CHIPPEWA COUNTY UNTIL THE LAST HOUR OR TWO. THIS WILL CONTINUE THOUGH ABOUT 09Z THEN THE COLD AIR DAM WILL BURST IN CANADA AND THE WINDS WILL TURN NE AND PUSH THE SNOW OUT OF THE EAST END OF THE CHIPPEWA COUNTY. && .LONG TERM.../ISSUED AT 350 PM/...FRIDAY AND BEYOND FRIDAY AND FRIDAY NIGHT...ONE MORE COLD DAY ALTHOUGH CORE OF COLDEST AIR BEGINS TO MODIFY AND SLIDE EAST DURING THE AFTERNOON AND ESPECIALLY TOMORROW NIGHT. MEANWHILE...SYNOPTIC MOISTURE THINS AS WE GO THROUGH THE DAY AND ESPECIALLY FRIDAY NIGHT WHILE INVERSION HEIGHTS GRADUALLY LOWER. STILL PLENTY OF OVER WATER INSTABILITY HOWEVER WITH DELTA T/S RUNNING IN THE LOWER TO MIDDLE 20S. AND WITH THAT...LAKE EFFECT SNOW SHOWERS WILL CONTINUE THROUGH THE DAY ON A PREVAILING WESTERLY FLOW...FOCUSED PRIMARILY IN AREAS ALONG AND NORTH OF M-32 IN NW LOWER MICHIGAN...ACROSS THE BROADEST PORTION OF THE LAKE. WANING MOISTURE AND LOWERING INVERSIONS SHOULD KEEP ACCUMULATIONS IN CHECK AND HAVE UP TO A FEW INCHES FOR THE FAVORED AREAS. FOR FRIDAY NIGHT...WINDS BACKING SW AHEAD OF SATURDAYS SYSTEM WILL PUSH REMAINING LAKE EFFECT INTO THE STRAITS AREA WHILE SOME LIGHT SYNOPTIC SNOWFALL MAY REACH THE FAR WESTERN PORTION OF THE CWA BY MORNING. SATURDAY AND SUNDAY...GFS AND ECMWF (AND NOW THE NAM) HAVE COME INTO SOME CONSENSUS IN REGARD TO DROPPING ANOTHER CLIPPER SYSTEM INTO THE MIDWEST LATE FRIDAY NIGHT THROUGH SATURDAY...CROSSING THE LOWER PENINSULA SAT NIGHT INTO SUNDAY. MODELS HAVE TRENDED THIS SYSTEM STRONGER BUT WITH A TRACK STILL PRETTY MUCH CUTTING ACROSS FAR SRN LOWER MICHIGAN ON SATURDAY. THIS SYSTEM CERTAINLY HAS THE POTENTIAL TO PRODUCE HEAVIER SNOW ACROSS THE REGION THROUGH A COMBINATION OF WARM ADVECTION AND DEFORMATION SNOWFALL...POSSIBLE TROWAL STRUCTURE SLIDING THROUGH LOWER MICHIGAN...AS WELL AS LAKE ENHANCEMENT POTENTIAL ESPECIALLY OFF LAKE HURON SATURDAY NIGHT THROUGH SUNDAY AS THE LOW PASSES BY TO THE SOUTH. SEVERAL INCHES OF SNOW ARE POSSIBLE ESPECIALLY ACROSS THE SRN COUNTIES AND OVER PORTIONS OF NE LOWER/ EASTERN UPPER MICHIGAN (DUE TO LAKE ENHANCEMENT) AND MAY ULTIMATELY REQUIRE SOME COMBINATION OF ADVISORIES AND WARNINGS. BUT...GIVEN THAT THIS IS PRIMARILY A 4TH-5TH PERIOD EVENT WITH STILL SOME UNCERTAINTY TO THE EVOLUTION OF THIS SYSTEM WILL REFRAIN FROM ANY WATCH HEADLINES BUT HIT WORDING HARDER IN THE HWOAPX. EXTENDED PERIODS...HIGH AMPLITUDE LONG WAVE HEMISPHERIC PATTERN REMAINS RELATIVELY UNCHANGED INTO EARLY NEXT WEEK...WITH SHARP RIDGING ALONG THE WEST COAST AND SHARP TROUGHING OVER THE EAST CONTINUING TO HANG ON. EVEN SO...GUIDANCE CONTINUES TO SUGGEST A FAIR AMOUNT OF TEMPERATURE MODIFICATION BY EARLY NEXT WEEK WITH INCREASING HEIGHTS AND H8 TEMPS "WARMING" INTO THE NEGATIVE TEENS. THUS...STILL ANTICIPATE HIGHS REBOUNDING THROUGH THE 20S FOR THE MONDAY-TUESDAY TIME FRAME. IN TERMS OF SENSIBLE WEATHER...MAY BE YET ANOTHER PIECE OF ENERGY AND SFC WAVE DROPPING THROUGH THE REGION DURING THE MONDAY-TUESDAY TIME FRAME BRINGING ANOTHER ROUND OF SYNOPTIC SNOWFALL AND RENEWED LAKE EFFECT SNOW SHOWERS. WEDNESDAY AND BEYOND...GFS/ECMWF SOLUTIONS CONTINUE TO SUGGEST SHARP RIDGE/TROUGH PATTERN ACROSS THE CONUS BREAKING DOWN TO A FAIR DEGREE DURING THE MIDWEEK PERIOD. HOWEVER...TODAYS SOLUTIONS ARE LESS AGGRESSIVE WITH THIS IDEA MAINTAINING SOME RIDGING ALONG THE WEST COAST AND OF COURSE TROUGHING IN THE EAST (HUGE SURPRISE THERE). NONETHELESS STILL LOOKING TO CATCH A MIDWEEK BREAK FROM THE WINTER WEATHER AS SHARP SFC RIDGE AND SOME SEMBLANCE OF A THERMAL RIDGE NOSES THROUGH THE GREAT LAKES ON WEDNESDAY. THUS BEST DAY OVER THE NEXT SEVEN DAY STRETCH LOOKING TO COME ON WEDNESDAY WHILE SNOW CHANCES RETURN AGAIN FOR THURSDAY WITH ANOTHER COLD FRONT APPROACHING THE REGION FROM THE NORTH. THEN...BREAK IN THE WINTRY WEATHER MAY BE SHORT LIVED AS MEDIUM RANGE GUIDANCE BREAKS OFF ANOTHER PIECE OF ARCTIC AIR THAT SLIDES DOWN INTO THE GREAT LAKES AT THE END OF NEXT WEEK. ADAM && .MARINE.../ISSUED AT 350 PM/ WINDS WILL BRIEFLY PICK UP OVER THE LAKES OVERNIGHT AS THE GRADIENT STRENGTHENS A BIT. THIS WILL PROMPT KEEPING THE SCA UP OVERNIGHT. && .AVIATION.../ISSUED AT 651 PM/...VALID FOR 00Z TAFS LAKE EFFECT REGIME EXPECTED TO CONTINUE THROUGH FRIDAY AFTERNOON...BRINGING LOW END VFR/HIGH END MVFR CONDITIONS TO ALL TAF SITES. STILL THINKING THE GREATER EMPHASIS FOR ADDITIONAL SNOW SHOWERS WILL BE FOUND A KTVC. MSB && .APX WATCHES/WARNINGS/ADVISORIES... MI...WIND CHILL ADVISORY UNTIL 7 AM EST FRIDAY FOR MIZ008-015>036-041- 042. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST FRIDAY FOR MIZ008-019- 020-022-025-026-028-031-032. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST FRIDAY FOR MIZ021-027. LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST SATURDAY FOR LMZ323-342- 344>346. LH...SMALL CRAFT ADVISORY UNTIL 5 AM EST FRIDAY FOR LHZ346>349. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 500 PM EST THU JAN 15 2009 .SYNOPSIS... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW AN AMPLIFIED PATTERN ACROSS NAMERICA WITH PRONOUNCED RIDGE OVER THE W AND A DEEP TROF OVER THE E. ARCTIC AIRMASS IS WELL ENTRENCHED FROM THE UPPER MISSISSIPPI VALLEY EWD. 12Z RAOBS INDICATED 850MB TEMPS OF -25C OR LWR FROM MN E TO NRN NEW ENGLAND AND N TO HUDSON BAY. TYPICAL PURE LES PATTERN IS UNDERWAY ACROSS THE UPPER LAKES. COLD AIR IS LEADING TO SMALL FLAKE SIZE THAT IS EXTREMELY EFFECTIVE AT REDUCING VIS... BUT DOES NOT ACCUMULATE SIGNIFICANTLY. IF DRIVING...IT CAN BE A WHITEOUT AROUND OTHER VEHICLES KICKING UP THE DRY SNOW. SFC OBS SUGGEST A MESOLOW LOCATED JUST W OR NW OF WHITEFISH PT...AND MONTREAL RIVER RADAR SHOWS A WIDE BAND OF SNOW JUST N AND W OF WHITEFISH PT WHERE STRONG CONVERGENCE IS OCCURRING. AWAY FROM THE LES...DRY AIRMASS HAS LED TO MOSTLY SUNNY SKIES THOUGH THERE HAS BEEN SOME DIURNAL STRATOCU DEVELOPMENT INLAND. TEMPS THIS AFTN HAVE FAILED TO RISE ABOVE 0F OVER MUCH OF THE NW HALF OF THE FCST AREA DESPITE SUN. && .SHORT TERM (TONIGHT/FRI)... LITTLE CHANGE WILL OCCUR IN THE PATTERN TONIGHT. LOW-LEVEL WINDS WILL BACK A BIT AS LARGE HIGH PRES OVER THE CNTRL PLAINS DRIFTS E. SO...THERE SHOULD BE A SLIGHT N SHIFT OF THE SRN EDGE OF LES OVER WRN UPPER MI THRU THE NIGHT...AND BACK EDGE OF LES TO THE E SHOULD GRADUALLY SHIFT E ACROSS ALGER COUNTY. HIGH RES MODELS SUGGEST NW TO N FLOW ACROSS LAKE SUPERIOR WILL SHIFT MESOLOW OVER FAR SE LAKE SUPERIOR TO THE SE FOR A TIME TONIGHT BEFORE STRENGTHENING LAND BREEZES OWING TO SHARP TEMP DROP OVER LAND CAUSES REDEVELOPMENT BACK TO THE NW OVER THE LAKE. SO...HEAVIEST SNOW TONIGHT WILL LIKELY FALL ROUGHLY FROM THE GRAND MARAIS AREA ACROSS NRN LUCE COUNTY DUE TO FOCUSED CONVERGENCE. STILL...GIVEN HOW COLD THE AIRMASS IS...IT WILL BE DIFFICULT TO GET DENDRITES TO FORM...SO SNOW-TO-WATER RATIOS WILL CONTINUE TO BE LOWER THAN USUAL FOR LES. MAY SEE LOCALIZED ACCUMULATIONS UPWARDS OF 4 INCHES IN PLACES THAT REMAIN UNDER DOMINANT BANDS THE LONGEST. LES ADVY WILL REMAIN UP FOR ALGER/NRN SCHOOLCRAFT/LUCE...MAINLY DUE TO THE EXTREMELY POOR VIS WITH THIS TYPE OF ARCTIC AIR LES. OTHERWISE...DON`T EXPECT MORE THAN 1-2 INCHES IN THE LES AREAS TONIGHT. AS FOR TEMPS...ALTHOUGH CENTER OF SFC HIGH PRES WILL BE PASSING WELL S OF HERE...WINDS MAY DECOUPLE MORE THAN WHAT MODELS SUGGEST AWAY FROM LAKE SUPERIOR. HAVE LOWERED MINS FROM INHERITED FCST AND UNDERCUT THE LOWEST MOS GUIDANCE BY 3-8 DEGREES. MINS OF -20 TO -25F SHOULD BE FAIRLY COMMON FROM WRN MARQUETTE COUNTY TO CRYSTAL FALLS AND KIWD. IF WINDS DIMINISH MORE THAN EXPECTED...TEMPS MAY PLUMMET TO -30F IN THE TYPICAL COLD SPOTS. BASED ON FCST WINDS/TEMPS...GOING WIND CHILL HEADLINES TONIGHT THRU FRI MORNING APPEAR ON TRACK. WAA WILL BE UNDERWAY FRI WITH A CONTINUED SLOW BACKING OF WINDS. SO BACK EDGE OF LES WILL CONTINUE TO SHIFT GRADUALLY N OVER THE WRN U.P. AND GRADUALLY E TO THE E OF MUNISING. ACCUMULATIONS AGAIN SHOULD BE IN THE 1 TO LOCALLY 4 INCH RANGE WITH THE HIGHER AMOUNTS E OF GRAND MARAIS. SHOULD BE A FAIR AMOUNT OF SUN AWAY FROM LES...AND WITH WAA...TEMPS SHOULD TOP OUT IN THE SINGLE DIGITS ABOVE ZERO EVERYWHERE. .LONG TERM (FRIDAY NIGHT THROUGH NEXT THURSDAY)... POSITIVE PNA PATTERN PERSISTS WITH RIDGE ALONG WRN NOAM AND TROUGH OVR MUCH OF ERN NOAM INTO GREENLAND. EVENTUALLY...TROUGH UPSTREAM OVR PACIFIC EDGES EAST WHICH BUCKLES THE PATTERN DOWNSTREAM INTO THE CONUS. SLIGHT WIGGLE IN THE PATTERN ALLOWS HEIGHTS TO GRADUALLY BUILD OVR NRN PLAINS INTO WRN PERIFERY OF GREAT LAKES. RESULT IS A NOTABLE WARMING TREND BY EARLY NEXT WEEK BEFORE ANOTHER SURGE OF COLD AIR COMES SOUTH INTO THE UPR LAKES LATE NEXT WEEK. CLIPPER LOW PRESSURE SYSTEM COULD BRING SOME WIDESPREAD SNOW ON SAT. OTHERWISE...LK EFFECT SNOW CONTINUES IN NW/N FLOW AREAS THROUGH NEXT TUE. FOLLOWED A TRACK TO THE SAT CLIPPER BTWN THE FARTHER WEST NAM AND REGIONAL CANADIAN AND THE FARTHER EAST GFS/ECMWF. A BIT LEARY OF GOING WITH ANY SOLUTION ON THE FAR EAST SIDE OF GUIDANCE AS LOW PRESSURE SYSTEMS THE LAST WEEK ENDED UP DIGGING FARTHER SOUTH THAN GUIDANCE INDICATED. EVEN SO...A NAM/GFS/ECMWF BLEND BRINGS SHORTWAVE AND SWATH OF DEEPER MOISTURE THROUGH MOST OF UPR MI LATE FRI EVENING INTO SAT. LOWEST CONDENSTAION PRES DEFICITS ON THE 280K ISENTROPIC SFC MORE OVR CNTRL WI WITH AVG MIXING RATIOS TOWARD UPR MI BORDER 1.5-2.0 G/KG WHICH SUPPORTS 3-4 INCHES OF SNOW IN 12 HR. THIS JIVES WELL WITH EXPECTED QPF AMOUNTS UP TO 0.25 INCH. ALSO...SW/S H95-H85 WINDS OVR NRN LK MICHIGAN INTO SRN SCHOOLCRAFT FM 06Z SAT THROUGH 18Z SAT (BASICALLY DURING THE MAXIMUM SYNOPTIC SUPPORT) WITH SUFFICIENT LAKE INDUCED INSTABILITY COULD ENHANCE THE SNOW. DEEP FAVORABLE SNOW GROWTH ZONE (TO 200 MB THICK) ON THE NRN LK MI SOUNDING FM BOTH GFS/NAM WILL LEAD TO HIGHER SNOW-WATER RATIOS. MAIN NEGATIVE FACTOR FOR SIGNIFICANT HEAVY SNOW IS STEADILY VEERING LOW LEVEL WINDS FM SW TO SE. NOTABLE SHEAR IS ALSO PRESENT IN LOWEST LEVELS. MADE A SIGNIFICANT UPWARD ADJUSTMENT TO POPS IN THE FRI NIGHT AND SAT TIME FRAME. ADVY LEVEL SNOWS ARE CERTAINLY POSSIBLE...ESPECIALLY CLOSER TO LK MICHIGAN WITH ONSHORE FLOW. WILL ALSO HAVE TO WATCH THE LK EFFECT FOR SAT NIGHT INTO SUN AM. SFC TROUGH POKING UP FM DEPARTING SFC LOW. THIS SYNOPTIC BOUNDARY MAY ENHANCE LOW-LEVEL CONVERGENCE EVEN AS GRADIENT WINDS LIGHTEN. MESOSCALE EFFECTS WILL LIKELY DOMINANTE WHERE BEST LAKE EFFECT DEVELOPS. SOUNDINGS SHOW THE DEEPER SNOW GROWTH LAYER HANGING ON INTO SUN. SO...WHERE THE SNOW OCCURS SNOW RATIOS STAY ON THE HIGH SIDE RESULTING IN POTENTIAL LOCALIZED...BUT MODERATE ACCUMS. MORE TRADITIONAL NW FLOW LAKE EFFECT SHOULD DEVELOP INTO SUN AS SYNOPTIC TROUGH SHIFTS EAST. LOWERING INVERSIONS AND DECREASING MOISTURE IN THE LK EFFECT LAYER DIMINISHES THE SNOW. BOTH GFS/ECMWF NOW INDICATE NEXT CLIPPER DROPS WELL TO THE SOUTH OF UPR LAKES SUN NIGHT INTO MON. SYNOPTIC SNOW CHANCES SEEM TO BE MINIMAL. KEPT SOME LOW POPS IN THROUGH TUE...BUT BEST SNOW CHANCES ARE IN THE LK EFFECT SNOW AREAS OF THE NRN CWA. FINALLY...AS MENTIONED EARLIER THERE REMAINS A SIGNAL FOR A MORE NOTABLE WARMUP FOR MIDDLE OF NEXT WEEK. GFS/ECMWF INDICATE AN H85 TEMP PATTERN ALSO SHOWN BY GFS ENS AND NAEFS. MIXING TO H85 WITH LACK OF STRONG WINDS IS VERY UNLIKELY...BUT STILL MIXING TO H9 TEMPS EXPECTED YIELDS LWR 30S WHICH WAS CLOSE TO GOING HPC GUIDANCE. COULD EVEN SEE TEMPS WELL INTO THE 30S IF ENOUGH SUSHINE IS REALIZED. AS ALWAYS...COULD BE SOME LGT PCPN WITH THE WARM AIR ADVECTION. PROGS LOOKED QUITE DRY THOUGH AS SOURCE AIRMASS IS OFF THE NRN ROCKIES AND NRN PLAINS. KEPT THE POPS OUT AS A RESULT. GFS AND LATEST ECMWF ARE INSISTENT THAT COLD AIR RUSHES BACK IN LATE NEXT THU INTO FRI. H85 TEMPS HEAD BACK TOWARD -25C BY 12Z FRIDAY. SO...IT APPEARS THAT THE WARM UP NEXT WEEK WILL ONLY BE BRIEF. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... AT KCMX...WITH NW FLOW OF VERY COLD ARCTIC AIR CONTINUING DURING THIS FCST PERIOD...LES/SOME BLSN WILL CONTINUE. PERSISTENCE FCST APPEARS THE WAY TO GO AS LITTLE OVERALL CHANGE IN AIRMASS WILL OCCUR THRU FRI MORNING. EXPECT IFR/LIFR CONDITIONS TO PREVAIL AT KCMX. AT KSAW...DOWNSLOPING COMPONENT WITH WNW WIND WILL RESULT IN VFR CONDITIONS PREVAILING THRU THIS FCST PERIOD. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... THERE WILL BE A FEW GALE FORCE GUSTS OVER PORTIONS OF SCNTRL LAKE SUPERIOR TONIGHT IN TIGHTER GRADIENT CAUSED BY MESOLOW NEAR WHITEFISH PT. OTHERWISE...NO GALE FORCE WINDS ARE EXPECTED DURING THIS FCST PERIOD. HEAVY FREEZING SPRAY WILL CONTINUE TONIGHT/FRI UNDER ARCTIC AIRMASS/BLUSTERY CONDITIONS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WIND CHILL ADVISORY UNTIL 10 AM EST /9 AM CST/ FRIDAY FOR MIZ001- 003-006-007-012>014-085. WIND CHILL WARNING UNTIL 12 PM EST /11 AM CST/ FRIDAY FOR MIZ002- 004-005-009>011-084. LAKE EFFECT SNOW ADVISORY UNTIL 4 PM EST FRIDAY FOR MIZ006-007- 085. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST FRIDAY FOR LSZ263>267. HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR LSZ162. && $$ SYNOPSIS...ROLFSON SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 616 PM CST FRI JAN 16 2009 .AVIATION.../00Z TAF ISSUANCE/ NEXT LOW TO EFFECT THE REGION IS CURRENTLY OVER LAKE WINNIPEG AND IS QUICKLY DROPPING TO THE SOUTHEAST. AHEAD OF THIS LOW...SOUTHERLY WINDS AND WARM ADVECTION HAVE OVERSPREAD MN AND WI. AS A RESULT WIDESPREAD MVFR CIGS CAN BE FOUND WITH SOME SCATTERED FLURRIES. CIGS RANGE ANY WHERE FROM 15K FT NEAR KAXN TO OVER 5K FT IN PARTS OF SRN MN...ALTHOUGH MOST TAF SITES HAVE CIGS AROUND 3K FT. EXPECT AT LEAST MVFR CIGS TO HANG AROUND THROUGH THE ENTIRE TAF PERIOD FOR ALL SITES AS AMPLE LOW LEVEL MOISTURE WILL REMAIN TRAPPED WITHIN THE BOUNDARY LAYER. WORST CONDITIONS WILL OCCUR ACROSS WI TAFS BETWEEN 09Z AND 15Z AS THE LOW TRACKS FROM NE ND TO NEAR KEAU BY 15Z SATURDAY. FEEL KEAU WILL HAVE THE WORST CONDITIONS IN THE MORNING AS HEAVIER SNOW MOVES BY. FOR NOW WILL BRING KEAU`S VSBY DOWN TO 2SM AND CIGS TO 1K FT...BUT THEY MAY END UP WORSE FOR A TIME...WILL SEE IF WE CAN GET A BETTER HANDLE ON WHEN THE HEAVIER SNOW MAY MOVE THROUGH THERE BEFORE GOING ANY LOWER. AFTER THAT...LOW QUICKLY MOVES OFF INTO MICHIGAN...WHICH WILL PULL A COLD FROM THROUGH THE CWA. THIS WILL TURN WINDS FROM THE SOUTH TO THE NORTHWEST BY 18Z AS WE GET BACK INTO A WEAK COLD ADVECTION REGIME. BASED ON BUFKIT SOUNDINGS...POTENTIAL FOR GUSTY WINDS TOMORROW AFTERNOON LOOKS LIKELY...SO HAVE ADDED GUSTS EVERYWHERE FOR AFTER FROPA. WENT A LITTLE HIGHER THAN GUIDANCE WITH SPEEDS...GIVEN 30 KT PLUS WINDS PROGGED TO BE WITHIN THE BOUNDARY LAYER. FINALLY...HAVE REINTRODUCED FLURRIES INTO THE END OF THE KMSP TAF...AS CYCLONIC FLOW...SOME FRONTOGENESIS...AND A WEAK SHORTWAVE MAY LEAD TO YET ANOTHER ROUND OF LIGHT SNOW FOR THE AREA SUNDAY. && .PREV DISCUSSION... /ISSUED 326 PM CST FRI JAN 16 2009/ THE WARMING TREND HAS BEGUN WITH A FEW FLURRIES DEVELOPING FROM IA INTO CENTRAL MN. THE PRECIP TYPE STILL A LITTLE PROBLEMATIC TONIGHT. MAINLY LOW LEVEL MOISTURE THIS EVENING...AND FORECAST SOUNDINGS BOUNCE AROUND A BIT WITH SATURATION AROUND -10C. THERE ARE A FEW HOURS HERE AND THERE WHERE FREEZING MIGHT BE THE PRECIP TYPE..DURING THE EVENING AND SHORTLY AFTER MIDNIGHT. SIG SHORT WAVE SHOWING UP ON WATER VAPOR MODELS ESPECIALLY THE RUC AND NAM BRING IN WELL DEFINED OMEGA IN THE -15 C PLANE AND INCREASING THETA E ADVECTION. THIS WILL HELP TO BRING MORE COLUMN MOISTURE LATER TONIGHT AND SATURDAY MORNING. MICH OF THE FORCING COMES TOGETHER OVER EAST EASTERN MN AND WEST CENTRAL WI. WILL KEEP THE HIGHER POPS IN WI BUT INCREASE BACK INTO MN A BIT. UP TO 3 INCHES OF SNOW STILL POSSIBLE FOR PARTS OF WEST CENTRAL WI. WILL CONTINUE THE RISING TEMPE TREND OVERNIGHT AND MAY HAVE TO DO SOME LAST MINUTE ADJUSTMENTS. THE UPPER RIDGE IS STILL STRONG AFTER THE WAVE MOVES THROUGH SATURDAY MORNING...AND THE ASSOCIATED UPPER JET IN A NORTH TO SOUTH ORIENTATION TO OUR WEST WILL KEEP THE MORE SIGNIFICANT WARMING AT BAY UNTIL TUESDAY. A FEW MINOR RIPPLES MOVING SSE MAY GENERATE A FEW FLURRIES SATURDAY NIGHT INTO SUNDAY. THE WARMEST DAY STILL LOOKS LIKE WEDNESDAY AHEAD OF THE COLD FRONT. COULD EASILY SEE SOME MID 30S. GFS AND ECMWF THEN IN GENERAL AGREEMENT BRINGING ANOTHER ARCTIC INTRUSION BY FRIDAY..ALTHOUGH NOT AS INTENSE AS THE CURRENT AIRMASS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ 99/99 mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 326 PM CST FRI JAN 16 2009 .DISCUSSION... THE WARMING TREND HAS BEGUN WITH A FEW FLURRIES DEVELOPING FROM IA INTO CENTRAL MN. THE PRECIP TYPE STILL A LITTLE PROBLEMATIC TONIGHT. MAINLY LOW LEVEL MOISTURE THIS EVENING...AND FORECAST SOUNDINGS BOUNCE AROUND A BIT WITH SATURATION AROUND -10C. THERE ARE A FEW HOURS HERE AND THERE WHERE FREEZING MIGHT BE THE PRECIP TYPE..DURING THE EVENING AND SHORTLY AFTER MIDNIGHT. SIG SHORT WAVE SHOWING UP ON WATER VAPOR MODELS ESPECIALLY THE RUC AND NAM BRING IN WELL DEFINED OMEGA IN THE -15 C PLANE AND INCREASING THETA E ADVECTION. THIS WILL HELP TO BRING MORE COLUMN MOISTURE LATER TONIGHT AND SATURDAY MORNING. MICH OF THE FORCING COMES TOGETHER OVER EAST EASTERN MN AND WEST CENTRAL WI. WILL KEEP THE HIGHER POPS IN WI BUT INCREASE BACK INTO MN A BIT. UP TO 3 INCHES OF SNOW STILL POSSIBLE FOR PARTS OF WEST CENTRAL WI. WILL CONTINUE THE RISING TEMPE TREND OVERNIGHT AND MAY HAVE TO DO SOME LAST MINUTE ADJUSTMENTS. THE UPPER RIDGE IS STILL STRONG AFTER THE WAVE MOVES THROUGH SATURDAY MORNING...AND THE ASSOCIATED UPPER JET IN A NORTH TO SOUTH ORIENTATION TO OUR WEST WILL KEEP THE MORE SIGNIFICANT WARMING AT BAY UNTIL TUESDAY. A FEW MINOR RIPPLES MOVING SSE MAY GENERATE A FEW FLURRIES SATURDAY NIGHT INTO SUNDAY. THE WARMEST DAY STILL LOOKS LIKE WEDNESDAY AHEAD OF THE COLD FRONT. COULD EASILY SEE SOME MID 30S. GFS AND ECMWF THEN IN GENERAL AGREEMENT BRINGING ANOTHER ARCTIC INTRUSION BY FRIDAY..ALTHOUGH NOT AS INTENSE AS THE CURRENT AIRMASS. && .AVIATION... /18Z TAF ISSUANCE/ MVFR CEILINGS TRYING TO DEVELOP IN THE WAKE OF S/SV MOVING THROUGH IA/MO REGION THIS MORNING. LOW LEVEL WAA ZONE LEFT IN ITS WAKE ACROSS SOUTHWEST MN HELPING CLOUDS ALONG. APPEARS MODELS HAVE PICKED UP ON THIS MORE RAPID LOW CLOUDS DEVELOPMENT SO WILL MOVE ACROSS MN PORTION OF THE FA THIS AFTERNOON. WILL LIKELY SEE SOME -SHSN TOO...BRIEFLY MVFR VSBYS ASSOCIATED. WILL WORK CLOUDS INTO WC WI REGION AFTER 22Z. NEXT S/WV CLIPPER SYSTEM TO AFFECT REGION DURING THE EVENING. WILL MENTION -SN DEVELOPING NORTHERN AREAS BY 05Z...SPREADING IFR CEILINGS SOUTH ACROSS AREA. SOME THREAT OF -FZDZ PER DRIER MID LEVELS INITIALLY...BUT WILL BE RATHER SCT NOT WIDEPSREAD. SFC LOW MOVES ACROSS FAR EASTERN AREAS WITH GENERAL MVFR VSBYS IN -SN WITH THE EXCEPTION OF KEAU/KRNH. SOUTH WINDS WILL INCREASE IN THE EVENING BECOMING NORTHWEST LATE TONIGHT/SAT MORNING AND WILL INCREASE. WILL MAINTAIN MVFR CEILING WITH THE POSSIBILITY OF -SN. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JPR/DWE mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 327 PM CST FRI JAN 16 2009 .SHORT TERM...TONIGHT THROUGH MONDAY. MORNING CLOUDS EXITING THE AREA...WITH MORE MOVING IN FROM WESTERN NEBRASKA. SUBJECTIVE 12Z UA ANALYSIS INDICATES A RIDGE BUILDING IN WESTERN US WITH AN EMBEDDED SHORT WAVE BEGINNING TO SLIDE SOUTH FROM ALBERTA. WAVE WILL MOVE QUICKLY THROUGH THE AREA SATURDAY. RIDGE RESULTS IN NORTHWEST FLOW FOR CWA..WITH WAA NOTED AT H85...ALONG WITH THIN BAND OF MOISTURE LOCATED ACROSS WESTERN NEBRASKA NORTH THROUGH WESTERN NORTH DAKOTA...WHICH WILL QUICKLY EXIT THE REGION. WARM FRONT EXTENDING FROM NORTHWESTERN NORTH DAKOTA THROUGH CENTRAL SOUTH DAKOTA...JUST BEGINNING TO CLIP WESTERN COUNTIES IN CWA. FRONT WILL BRING A WIND SHIFT...AND WARMER TEMPS. MAIN FORECAST CHALLENGE LIES IN TEMPS AS CWA LIES ON WRN EDGE OF CYCLONIC FLOW IN WAKE OF GT LAKES TROUGH. AT THIS POINT...CWA IS JUST OUTSIDE REGION OF PRECIP POTENTIAL...BUT SMALL VARIATION IN THE LOCATION OF THE BAROCLINIC ZONE JUST EAST OF THE CWA COULD MAKE A DIFFERENCE. MODELS DISAGREED ON WESTERN EXTENT OF MOISTURE...WITH GFS BRINGING MOISTURE INTO CWA...WHILE NAM AND EURO IN RELATIVE AGREEMENT KEEPING NARROWER SWATH OF MOISTURE WELL TO THE EAST OF CWA. WAA WILL BRING NONDIRUNAL TEMPS OVERNIGHT...WITH MINS OCCURRING BEFORE MIDNIGHT...AND TEMPS RISING THOUGH THE EARLY MORNING HOURS. FRONTAL PASSAGE SATURDAY ASSOCIATED WITH FAST MOVING SHORTWAVE SHOULD REMAIN DRY. WHILE FRONT WILL BRING SHALLOW MOISTURE...CROSS SECTIONS INDICATE LIFT WILL OCCUR BEFORE DEEPER MOISTURE ARRIVES. THEREFORE...KEPT FORECAST DRY...WITH BETTER CHANCE OF PCPN TO THE NORTHEAST OF CWA...CLOSER TO UPPER LEVEL FORCING. AGAIN DROPPED TEMPS SLIGHTLY FOR THE WEEKEND AS MODELS IN FAIR AGREEMENT OF A COOLER TREND. CAA MOVING OVER REGION SATURDAY AND SUNDAY...COMBINED WITH NORTHWEST WINDS AND LIMITED MIXING...WILL KEEP TEMPS LOWER. EXPECT HIGH TEMPS IN THE 30S...WITH THE SOUTHERN CWA SEEING READINGS IN THE 40S SATURDAY. INCREASED CLOUDS THROUGH WEEKEND AS CWA REMAINS ON WESTERN EDGE OF CYCLONIC FLOW. WAA RETURNS MONDAY BRINGING SLIGHTLY WARMER TEMPS. SHORTWAVE DROPPING SOUTH WILL BRING THE CHANCE FOR LIGHT PCPN NEAR THE CWA...ESPECIALLY IN THE NORTH MONDAY. IF PCPN OCCURS...TYPE IS IN QUESTION AS MODEL SOUNDING TEMPS COULD BE TOO WARM FOR SNOW...WITH FREEZING DRIZZLE OR RAIN A POSSIBILITY. LEFT OUT MENTION OF PRECIP DUE TO MODEL DISAGREEMENT AND BELIEVE ANY PCPN WOULD BE LIGHT. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY. GLANCE AT 06Z/12Z GFS DEPICTING MAJOR DIFFERENCES STARTING AT 12Z WED AND CONTINUES THRU THE REST OF THE FCST PD. MEANWHILE ECM RUN-TO-RUN SOLUTION COMPARISON IS GENERALLY BETTER...AND THUS WILL TREND TOWARD IT. WELL AMPLIFIED WRN RIDGE AND ERN TROF IS ADVERTISED EARLY IN THE PD BEFORE SHORTWAVE ENERGY BREAKS DOWN THE WRN RIDGE AND LARGE SCALE FLOW TRANSITIONS TO A BROAD TROF ENVELOPING MOST OF THE LOWER 48 BY THE END OF THE WEEK. PCPN CHANCES APPEAR NIL FOR THE MOST PART...BUT THE OVERALL TREND WILL BE DECREASING TEMPS WHEN ANOTHER ARCTIC AIRMASS INVADES THE PLAINS. COLDEST TEMPS OVER THE CWA SHOULD BE REALIZED BY FRIDAY WITH MORNING LOWS IN THE SINGLE DIGITS AND HIGHS BARELY CRACKING THE LOW/MID 20S. && .AVIATION... FOR TAF SITES KOFK/KOMA/KLNK THROUGH 17/18Z SATELLITE TRENDS MOVING BACK EDGE OF LOWER CIGS STEADILY EASTWARD THROUGH THE MORNING SUGGEST MODELS HAVING SOME TROUBLE IN HANDLING LOW LEVEL MOISTURE. NAM AND GFS FORECAST SOUNDINGS WANT TO HANG ON TO A LOW LEVEL MOIST LAYER AROUND 900MB THIS AFTN WHILE RUC TENDS TO BE DRIER...ESPECIALLY AT KLNK AND KOMA. WENT WITH SCT-BKN LAYER THRU 21Z TO HANDLE UNCERTAINTY BUT TREND EXPECTED TO BE TOWARD VFR CONDITIONS THRU 1712Z. NEXT COLD FRONT COMES INTO THE AREA TONIGHT WITH WINDS SHIFTING TO THE NW AND INCREASING 20-30KTS AROUND OR AFTER 1712Z. SOME MVFR CIGS INDICATED BEHIND THE FRONT 12Z-18Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...WILKINS/MAYES LONG TERM...DEE AVIATION...FOBERT ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 107 PM EST FRI JAN 16 2009 .SYNOPSIS... FRIGID ARCTIC AIR WILL REMAIN OVER THE AREA INTO SATURDAY. THIS ARCTIC AIR WILL PICK UP MOISTURE OFF LAKE ONTARIO, AND GIVE THE AREA SCATTERED SNOW SHOWERS AND FLURRIES. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATED AT 1130 AM...BASED ON CRNT RDR TRENDS...LES ADVISORY WIBIS FOR NRN ONEIDA THRU THE OVRNGT HRS. PREV BLO... UPDATED AT 1020 AM...MAIN FOCUS THIS AFTN WILL BE LES BAND EAST OF LAKE ONTARIO. A CLOSE CALL WITH SIG DIFFS IN THE SHORT RNG MDL GUIDANCE. 12Z NAM SUGGESTING MAIN FOCUS WILL BE N OF THE CWA WITH SUB-ADVISORY ACCUMS ACRS NRN ONEIDA. HOWEVER..THE RUC IS FURTHER S WITH THIS BAND...AND SUGGESTS HEADLINES WOULD BE NEEDED FOR NRN ONEIDA FOR LATE TDA INTO TNGT. A LOOK AT RUC-ANALYZED UPSTREAM WINDS SHOWS WEAK WAVES EMBEDDED WITHIN THE WRLY FLOW...AND INDICATES POTNL FOR BAND TO WORK INTO OR DROP SWD INTO NRN ONEIDA LATER THIS AFTN AS THE WRLY FLOW INCREASES. FOR NOW WE`LL STAY PUT WITH 1-3 ACCUMS NRN ONEIDA TDA...AND ANOTHER 1-3 TNGT...AND CONTINUE TO MONITOR. OTRW...MAY SEE SOME -SHSN FROM LAKE ERIE WORK INTO THE NRN FINGER LAKES THIS AFTN SO CHC POPS THERE...WITH JUST THE CHC FOR A FLURRY AND SLGT CHC POPS ELSEWHERE. PREV BLO... UPDATED AT 830 AM...A FEW TWEEKS TO ZONES/GRIDS TO REFLECT CRNT CONDITIONS. SVRL RPTS OF MINS IN THE -10 TO -20 RNG THIS MRNG. WINDS NOW PICKING UP WITH WIND CHILLS -15 TO -20 AT A FEW LOCATIONS. MAINLY CLEAR SKIES SRN TIER AND NE PA WITH -SHSN CONFINED TO TYPICAL LAKE AREAS. CUT BACK POPS A BIT ACRS THE SRN TIER AND NE PA...WHERE ONLY A FEW FLURRIES ARE XPCTD WITH PARTLY TO MOSTLY SUNNY SKIES. WILL KEEP AN EYE ON THE BAND E OF LAKE ONTARIO...LIGHT FLOW IS KEEPING HEAVIER SNOW CLOSER TO LAKE ONTARIO. AS WSW FLOW STRENGTHENS THIS AFTN XPCT IT TO XTND FURTHER INLAND...BUT BY THIS TIME IT SHUD BE FOCUSED N OF NRN ONEIDA. PREV BLO... LAKE ONTARIO SNOW BAND IS BARELY MAKING IT TO ONONDAGA COUNTY DUE TO LACK OF MOISTURE. WITHIN THE NEXT SEVERAL HOURS, WINDS WILL SHIFT AND CREATE A MORE OR LESS SW TO NE PAIR OF BANDS OFF ERIE AND ONTARIO. THE ERIE BAND MAY SKIRT OUR WESTERN FA, HENCE THE 50-60 POPS IN THIS VICINITY. HAVE EXTENDED DURATION OF WIND CHILL ADVISORY. WE MAY HAVE A FEW HOURS MID AFTERNOON WHERE WINDS FAIL TO BRING TEMPS TO ADVISORY CRITERIA, BUT TEMPS WILL QUICKLY PLUMMET TOWARD SUNSET. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... LAKE BANDS WILL FLUCTUATE OVERNIGHT. THERE IS A PERIOD OF 3 TO 6 HOURS WHERE IT APPEARS THE ONTARIO BAND WILL MAKE A RUN AT ONEIDA COUNTY, AND WE HAVE ADDED A FEW INCHES OF SNOW TO THE GRIDS. HOWEVER THE BANDS WILL SHIFT AGAIN TO NW TO SE DIRECTION HEADED INTO THE DAY SATURDAY. WE HAVE EXTENDED WIND CHILL ADVISORY UNTIL 16Z SATURDAY TO ACCOUNT FOR CONTINUING FRIGID AIRMASS AND MODERATE WIND COMBO. ANOTHER CLIPPER SYSTEM WILL MOVE INTO WESTERN PA LATE SATURDAY. WITH A LACK OF UPPER FLOW OVER THE REGION, THIS SYSTEM WILL STALL OUT AND BRING A GOOD 24-36 HOURS OF LIGHT SNOW INTO SUNDAY. TOTAL ACCUMS WILL LIKELY BE IN THE 2 TO 5 INCH RANGE OVER 36 HOURS. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... EXCEPT FOR RIGHT AT THE BEGINNING...NOTHING MUCH OF SIGNIFICANCE OCCURS IN THE MEDIUM RANGE FCST TODAY WITH AMPLIFIED TROF OVER THE EAST EARLY IN THE PERIOD EXPECTED TO FLATTEN OUT BY THURSDAY AND FRIDAY. THIS SHOULD PROVIDE A GRDL WARM UP OF SORTS. THE MON NITE-TUESDAY TIME FRAME POSES SOMEWHAT OF A PROBLEM GIVEN THAT THE GFS AND ECMWF MODELS ARE ABOUT 24 HRS APART IN EVOLUTION OF SIGNIFICANT COASTAL STORM. WE/RE LEANING WITH A CLOSER TO THE COAST EVENT THAN THE ECMWF...WITH TIMING PROBABLY SOMEWHERE IN THE MIDDLE GIVING US WRAPAROUND LAKE ENHANCED SNOWFALL MONDAY NIGHT FOLLOWING PSBL WDSPRD STORMINESS ON MONDAY. THEN...IT/S CONTINUED BELOW NORMAL COLD /BUT NOT AS FRIGID AS THIS WEEK/ WITH OCCASIONAL WEAK CLIPPER LOWS AND LAKE EFFECT SNOW CONDITIONS OVER UPSTATE NY...WITH VARIABLE CLOUDS AND FLURRIES IN NEPA. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... IFR CONDITIONS /MAINLY VSBY/ ARE EXPECTED TO DEVELOP AT RME THIS AFTERNOON AS LAKE EFFECT SNOW BAND CONTINUES TO PUSH EAST. EXPECT IFR IN SNOW WILL PERSIST UNTIL AFTER MIDNIGHT WHEN BAND IS FCST TO JOG BACK TO SLIGHTLY NORTH OF THE AIRPORT. ELSEWHERE...SOME VFR CIGS WILL WORK INTO SYR...OTHERWISE JUST EXPECTING VFR WITH SCT CLOUDS THROUGH THE PERIOD AT OTHER AIRPORTS. GUSTY WINDS THIS AFTERNOON MAY OCCASIONALLY PRODUCE MVFR VSBYS AT SYR. WEST WINDS 15 TO 30 KTS WILL DIMINISH TO UNDER 10 KTS TONIGHT FROM THE SOUTHWEST...CONTINUING THROUGH MIDDAY SATURDAY. SAT...VFR. SAT NGT-SUN...IFR IN OCNL SNOW. SUN NGT-MON...MVFR. CHC IFR IN SNOW AS LOW PRESSURE MOVES NORTH ALONG EAST COAST. MON NITE-TUE...VFR/MVFR. SCT LAKE SNOW SHOWERS CNTRL NY. WEDS...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...WIND CHILL ADVISORY UNTIL 12 PM EST SATURDAY FOR PAZ038>040- 043-044-047-048-072. NY...WIND CHILL ADVISORY UNTIL 12 PM EST SATURDAY FOR NYZ009- 015>018-022>025-036-037-044>046-055>057-062. LAKE EFFECT SNOW ADVISORY UNTIL 6 AM EST SATURDAY FOR NYZ009. && $$ SYNOPSIS...DJP NEAR TERM...DJP SHORT TERM...DJP LONG TERM...JAB AVIATION...JAB ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 723 AM EST THU JAN 15 2009 .SYNOPSIS...AN ARCTIC COLD FRONT WILL CROSS CENTRAL NORTH CAROLINA THIS MORNING. THE COLDEST CONDITIONS IN SEVERAL YEARS WILL GRIP OUR REGION BEHIND THE FRONT TONIGHT THROUGH SATURDAY... AS STRONG ARCTIC HIGH PRESSURE SETTLES OVERHEAD. A POTENT UPPER LEVEL DISTURBANCE WILL PIVOT ACROSS THE CAROLINAS SUNDAY AND SUNDAY NIGHT. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM... VERY LITTLE CHANGE TO CURRENT FORECAST. TIMING IS EVERYTHING AND CRITICAL TO THE TEMPERATURE FORECAST. UPSTREAM OBSERVATIONS AND RUC MODEL IMPLY COLD AIR BEGINS TO IMPACT THE WESTERN PIEDMONT BY 9 AM OR SO THIS MORNING. THURSDAY MORNING LOWS OF 28 TO 31 IN THE NORTHWEST PIEDMONT WILL HAVE LITTLE TIME TO RECOVER BEFORE LEVELING OFF MID MORNING AS SUNSHINE BATTLES THE COLD AIR ADVECTION FOR CONTROL OF TEMPERATURES. EXPECTING TEMPERATURES TO RISE A BIT ABOVE FREEZING NORTHWEST AND LEVEL OFF BEFORE FALLING MID AFTERNOON AND LATER. FURTHER EAST A BIT MORE TIME FOR SUNSHINE TO WORK ITS MAGIC AND MID 40S POSSIBLE IN THE CLINTON VICINITY. WINDS ALOFT IN THE EXPECTED MIXED LAYER TOP OUT AT ABOUT 25 MPH AND SURFACE GRADIENT DOES NOT IMPRESS. WILL BE SURPRISED IF WIND GUSTS EXCEED 25 MPH WITH ANY FREQUENCY TODAY. CASES SIMILAR TO TONIGHT IN THE 1968 TO 1997 GREENSBORO DATABASE ARE FEW. IF LOW LEVEL THICKNESS INDEED DROPS ABOUT 30 TO 35 METERS FROM EVENING TO SUNRISE FRIDAY... THERE IS A ROUGH INDICATION THAT THE DIURNAL TEMPERATURE FALL SHOULD BE ABOUT 24 TO 27 DEGREES. THUS IF WE CAN MAKE IT TO THE MID 30S IN THE NORTHWEST PIEDMONT TODAY... MOST LOCATIONS IF NOT ALL SHOULD BE ABLE TO AVOID SINGLE DIGIT TEMPERATURES OVERNIGHT. THE SAME ABOVE MENTIONED DATABASE CONTAINS ONLY A DOZEN OR SO SIMILAR CASES... WITH THE WARMEST GREENSBORO LOW AT 12 DEGREES. COMFORTABLE IN CONTINUING TO PLAY A SLIGHT COLD BIAS IN THE MODELS AND PLACE MOST LOWS AT 11 TO 13 WITH NEAR 18 IN THE EXTREME SOUTHEAST. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... AS OF 300 AM... VERY LITTLE CHANGE TO THE CURRENT FORECAST. GIVEN THE FORECAST THICKNESS AND INDICATED CONTINUED COLD AIR ADVECTION IN THE LOWEST FIVE THOUSAND FEET OF THE ATMOSPHERE... FRIDAY HIGHS OF 27 TO 32 ACCEPTED. VORTICITY CENTER ALOFT TO SWEEP THROUGH NORTHERN PARTS OF SOUTH CAROLINA FRIDAY NIGHT WITH SOME HIGH MOISTURE OR CIRRUS FOR NORTH CAROLINA BEFORE MOISTURE EXITS TO THE EAST... WELL BEFORE SUNRISE. SURFACE HIGH PRESSURE CENTERED OVER OR NEAR NORTH CAROLINA BY SUNRISE SATURDAY FOR CALM WINDS MUCH OF THE NIGHT. ONLY A COUPLE OF CASES ROUGHLY MATCHING SATURDAY MORNING IN THE 1968 TO 1997 DATABASE GIVING A ROUGH INDICATION OF A 16 TO 18 DEGREE DIURNAL TEMPERATURE FALL. THUS WILL FORECAST LOWS OF 10 TO 12 WITH READINGS NEAR 15 SOUTHEAST. GOOD WARMING ALOFT FRIDAY NIGHT AND SATURDAY. HOWEVER WITH SATURDAY MIXING HEIGHTS LIKELY LESS THAN 3000 FEET... THIS ENERGY WILL REMAIN LARGELY UNTAPPED. AFTERNOON HIGHS OF MID TO UPPER 30S MATCH WELL WITH THE EXPECTED MIXING HEIGHTS... THICKNESS VALUES AND GRADIENT. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 515 AM THURSDAY... A HIGHLY AMPLIFIED PATTERN ALOFT... FEATURING A WESTERN NOAM RIDGE AND DOWNSTREAM EASTERN NOAM TROUGH (POSITIVE PNA) WILL DEAMPLIFY/ BREAK DOWN BY THE MIDDLE OF NEXT WEEK... BEFORE PERHAPS RETROGRESSING AND RE-AMPLIFYING LATE NEXT WEEK INTO NEXT WEEKEND. WHILE IT APPEARS THAT THREE IMPRESSIVE SHORTWAVE TROUGHS WITHIN THE HIGHLY AMPLIFIED LONGWAVE PATTERN WILL CROSS OUR REGION DURING THE PERIOD -- ONE EACH DAY SUNDAY THROUGH TUESDAY -- DETAILS (TIMING/AMPLITUDE) OF THESE SHORTWAVES REMAIN PROBLEMATIC. SATURDAY NIGHT: TEMPERATURE SHOULD FALL QUICKLY INTO THE LOWER TO MIDDLE 20S AFTER SUNSET SATURDAY... GIVEN THE LINGERING ARCTIC SURFACE RIDGE AXIS ALONG THE COAST. TEMPERATURES EXPECTED TO LEVEL OFF IN THE 20 TO 23 DEGREE RANGE FOR OVERNIGHT LOWS... HOWEVER... AS LOW LEVEL SSW FLOW INCREASES ACROSS OUR REGION AHEAD OF THE FIRST OF THE S/W`S AND ATTENDANT CLIPPER-TYPE SFC LOWS. SUNDAY AND SUNDAY NIGHT: THE MEDIUM RANGE MODELS HAVE COME INTO BETTER AGREEMENT IN THEIR DEPICTION OF A SHARP... SHORT WAVELENGTH S/W TROUGH ALOFT CROSSING THE CENTRAL AND SOUTHERN APPALACHIANS SUNDAY AND EARLY SUNDAY NIGHT. THE RESULTANT INCREASING CONFIDENCE IN THE AMPLITUDE OF THE TROUGH AND ACCOMPANYING FORCING FOR ASCENT MAY PROVE SUFFICIENT TO PRODUCE SOME LIGHT PRECIPITATION ACROSS CENTRAL NC SUNDAY AFTERNOON AND EVENING. SINCE THE S/W IS EXPECTED TO REACH MAXIMUM AMPLITUDE JUST TO OUR WEST AND RESULT IN A BACKED SOUTHWESTERLY LOW AND MID LEVEL FLOW... IT WILL HAVE A BETTER OPPORTUNITY (THAN MOST "NW FLOW" TROUGHS) TO PRODUCE PRECIPITATION OVER CENTRAL NC. FURTHERMORE... THE FAVORED LEFT EXIT REGION OF THE UPPER JET... EAST OF THE TROUGH AXIS ALOFT... IS FORECAST TO BE VERY NEAR OUR REGION BY 00Z MONDAY. WILL ACCORDINGLY RAISE POPS INTO THE CHANCE RANGE BETWEEN ROUGHLY 18Z SUN AND 06Z MON... BUT THIS REMAINS A RELATIVELY LOW CONFIDENCE FORECAST. HIGH TEMPERATURES EXPECTED TO REACH THE UPPER 30S NW TO UPPER 40S SE. REGARDING P-TYPE: FORECAST THICKNESSES CONTINUE TO LIE IN THE "ALL SNOW" TO "INDETERMINATE TOO FEW CASES" ON THE P-TYPE NOMOGRAM. THE LATTER OF WHICH IS TYPICAL OF STEEP LAPSE RATE ENVIRONMENTS... SUCH AS THIS ONE PRODUCED BY THE AMPLIFYING TROUGH/COLD POOL ALOFT. FORECAST SOUNDINGS AND BOUNDARY LAYER TEMPERATURES INDICATE ALL LIQUID... EXCEPT A RAIN/SNOW MIX IN THE CLIMO FAVORED NW PIEDMONT DURING THE DAY SUNDAY... TRANSITIONING TO ALL SNOW NW TO RAIN/SNOW MIX SE SUNDAY EVENING. THIS WOULD APPEAR TO BE A RELATIVELY LOW IMPACT/LOW QP EVENT IF THE PRECIPITATION EVEN MATERIALIZES... BUT IT BEARS WATCHING AS THE WEEKEND NEARS... NONETHELESS. MONDAY THROUGH WEDNESDAY: A COUPLE MORE SHORTWAVE TROUGHS ARE EXPECTED TO CROSS OUR REGION ON MONDAY AND ANOTHER ON TUESDAY. THE L/W TROUGH AXIS SHOULD BE JUST EAST OF OUR LONGITUDE BY THAT TIME... HOWEVER... SO THESE ARE EXPECTED TO BE DRY (WITH TUESDAYS THE STRONGER OF THE TWO AND MORE APT TO PRODUCE PERHAPS A FLURRY OR SPRINKLE). TEMPERATURES SHOULD REMAIN BELOW AVERAGE THROUGH THE PERIOD GIVEN THE CONTINUED L/W TROUGHING INVOF THE EAST COAST AND POTENTIAL ENHANCED CLOUDINESS ASSOCIATED WITH THE EMBEDDED S/W`S... GENERALLY 40 TO 45 AND LOW TO MID 20S FOR HIGHS AND LOWS... RESPECTIVELY. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 720 AM THURSDAY... VFR CONDITIONS EXPECTED THROUGH THE 24-HOUR TAF PERIOD. NW WINDS WILL INCREASE TO 12-16 KTS WITH GUSTS 18-23 KTS BY MID MORNING AND CONTINUE THROUGH MID AFTERNOON... AS DENSE ARCTIC AIR SURGES ACROSS OUR REGION BEHIND A COLD FRONT CROSSING THE NC FOOTHILLS AT THE MOMENT. THE WIND SHOULD VEER TO MORE NW/NNW AND SUBSIDE INTO THE 8-13 KT RANGE WITH JUST AN OCCASIONAL GUST TO AROUND 15 KTS BY THIS EVENING... AS TURBULENT MIXING CEASES AND THE ARCTIC AIRMASS BECOMES ESTABLISHED OVER OUR AREA. LOOKING AHEAD...THE PRESENCE OF THE ARCTIC SURFACE RIDGE WILL RESULT IN VFR CONDITIONS WITH JUST PERIODS OF MID AND HIGH CLOUDS THROUGH SATURDAY NIGHT. A POTENT DISTURBANCE ALOFT WILL AMPLIFY SOUTHEASTWARD INTO THE CAROLINAS AND PRODUCE SOME LIGHT PRECIPITATION (RAIN/SNOW MIX) AND SUB-VFR CONDITIONS SUNDAY AFTERNOON AND EVENING... BEFORE A RETURN TO VFR CONDITIONS IN ITS WAKE BY LATE SUNDAY NIGHT AND MONDAY. && .CLIMATE... MOST RECENT DATES AT KRDU WHERE THE HIGH WAS BELOW 32... 12/14/05...31 1/19/05...30 1/18/05...30 MOST RECENT DATES AT KRDU WHERE THE LOW WAS IN THE TEENS... 1/21/08...15 1/20/08...18 2/19/07...19 2/17/07...19 2/6/07...15 THE LAST DATES AT KRDU WHERE THE LOW WAS IN THE SINGLE DIGITS... 1/29/00...7 1/28/00...1 MOST RECENT DATES AT KGSO WHERE THE HIGH WAS BELOW 32... 12/14/05...31 1/29/05...29 1/23/05...31 1/18/05...28 THE LAST DATES AT KGSO WHERE THE LOW WAS IN THE SINGLE DIGITS... 1/24/05...8 1/20/04...9 1/24/03...7 MOST RECENT DATES AT KFAY WHERE THE HIGH WAS BELOW 32... 12/20/04...30 1/26/04...29 MOST RECENT DATES AT KFAY WHERE THE LOW WAS IN THE TEENS... 1/21/08...18 1/4/08...17 2/19/07...19 2/17/07...19 2/6/07...18 && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MWS LONG TERM...MWS AVIATION...MWS nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAND FORKS ND 826 PM CST FRI JAN 16 2009 .DISCUSSION...MAIN CHALLENGE IS -SN AND TEMPS. STRONG 850MB WARM AIR ADVECTION ALONG AND EAST OF THE VALLEY CAUSING VERY FINE -SN WITH VSBY 1-3SM. ACCUMS HAVE BEEN A DUSTING OR LESS...WITH MAIN PROBLEM BEING SUCH FINE NATURE TO SNOW ALLOWING MELTING ON ROADWAYS WITH DRIVING CARS...THEN QUICKLY RE-FREEZING CAUSING `BLACK ICE`. THERE HAVE ALSO BEEN ISOLD REPORTS OF FREEZING DRIZZLE...BUT HIGH CLOUDS NOW PROPAGATING OVER THE FA...AND THIS SHOULD ELIMINATE ANY -FZDZ (SEEDING ICE NUCLEI). AT ANY RATE...PRECIP IS VERY LIGHT...AND NOT ENOUGH TO CAUSE WIDESPREAD PROBLEMS...NO ADVISORY NEEDED AT THIS POINT. FOLLOWED 00Z RUC FOR HOURLY TEMPS...WHICH FOLLOWED PRETTY CLOSE TO CURRENT FORECAST (STEADY TO SLOWLY RISING). WINDS STILL EXPECTED TO INCREASE ON BACKSIDE OF LOW...BUT SPEEDS STILL EXPECTED TO BE 20-30MPH...MOST LIKELY NOT ENOUGH TO PRODUCE WIDESPREAD BLOWING SNOW HAZARD. ALL IN ALL PREVIOUS FORECAST THINKING ON TRACK AND ONLY MAJOR CHANGE WILL BE TO RAISE POPS TO LIKELY FOR CURRENT WARM AIR ADVECTION -SN ALONG AND E OF VALLEY. && .AVIATION...BAND MVFR/IFR CIGS LOCATED ALONG AND EAST OF THE VALLEY...EXPECTED TO CONTINUE SLOW EASTWARD PROGRESS. 1-3SM VSBY IN -SN ASSOCIATED WITH THESE LOWER CIGS. THERE MAY BE A BRIEF PERIOD OF VFR CONDITIONS...BUT WILL BE SHORT LIVED WITH AREA MVFR CIGS MOVING SOUTH FROM CANADA. THESE CIGS SHOULD CONTINUE INTO MUCH OF SATURDAY. && .PREV DISCUSSION... /ISSUED 229 PM CST FRI JAN 16 2009/ SHORT TERM... FORECAST CHALLENGES WILL BE TEMPS THROUGHOUT THE ENTIRE FORECAST ..SNOW POTENTIAL TONIGHT AND THEN WHETHER THE GUSTY NORTHWEST WINDS LATER TONIGHT INTO SATURDAY CAN LOFT ANY OF THE SNOW. MODEL SOLUTIONS ARE VERY CONSISTENT WITH THE INHERITED FORECAST...SO VERY FEW FORECAST GRIDS NEED TO BE CHANGED. TONIGHT-SAT...SFC LOW TAKING SHAPE OVER EAST CENTRAL SASKATCHEWAN EARLY THIS AFTERNOON...WITH THE UPPER SHORT WAVE IN THE SAME AREA. THE LOW WILL DROP SOUTHEAST TONIGHT AND SHOULD REACH THE KMSP AREA TOWARD 12Z SAT. AS THE LOW TRACKS TOWARD THE CANADIAN BORDER BY 00Z SAT...TEMPS SHOULD CONTINUE TO RISE. THERE IS A POCKET OF WARM AIR ALOFT ALONG THE WESTERN EDGE OF THE FA WHERE IF ANY PCPN FALLS IT COULD REACH THE SFC AS VERY LIGHT FREEZING DRIZZLE. HOWEVER... IT HAS BEEN VERY DRY UPSTREAM AND WILL NOT ADD THIS INTO THE EVENING FORECAST AS IT SEEMS PRETTY REMOTE. MODELS HAVE BEEN BACKING OFF ON ANY QPF AMOUNTS IN THE WARM SECTOR AHEAD OF THE LOW. AS THE LOW MOVES THRU (MOSTLY AROUND OR AFTER MIDNIGHT) WE SHOULD SEE SLIGHTLY BETTER PCPN CHANCES...AND MORE SO IN THE NORTHEAST FA. 850MB TEMPS CRASH IN THE WAKE OF THE LOW WITH THE BEST COLD ADVECTION ACTUALLY DONE BY 06-09Z SAT...AND THEN GETTING BACK INTO WARM ADVECTION THEREAFTER. MODEL SOUNDINGS DIFFER ON HOW MUCH OF AN ADIABATIC LAYER WILL EXIST...BUT WINDS AT 925MB ARE AROUND OR JUST ABOVE 30KTS. THIS IN COMBINATION WITH A GOOD SFC PRESSURE GRADIENT SHOULD BRING SOME STRONGER WINDS DOWN TO THE SFC AND COULD CAUSE SOME BLOWING AND DRIFTING SNOW. WITH THE SNOWPACK SOMEWHAT COMPACTED NOW AND NOT MUCH NEW SNOW EXPECTED...DO NOT THINK ANY ADVISORY HEADLINE IS WARRANTED AT THIS POINT. WINDS STILL LOOK TO BE FAIRLY GUSTY INTO AT LEAST THE FIRST HALF OF SAT...SO WILL KEEP SOME BLOWING/DRIFTING SNOW MENTIONED IN THE FORECAST. WITH CLOUDS AND WARM AIR ADVECTION (AT LEAST FOR A WHILE)...THINK TEMPS WILL REMAIN STEADY OR SLOWLY RISE TONIGHT AND THEN RISE (HOPEFULLY) ANOTHER 5 TO 10F FOR SAT HIGHS. SAT NIGHT-MON...FA ESSENTIALLY STAYS IN FAIRLY HIGH AMPLITUDE NORTHERLY FLOW THROUGHOUT. PROBLEM WILL BE THAT WE ARE STILL IN CYCLONIC FLOW WITH WEAK PIECES OF VORTICITY ROTATING THROUGH... WHICH COULD BRING SOME CLOUDS/FLURRIES THROUGHOUT THIS PERIOD. WILL EXTEND SOME FLURRIES INTO SAT NIGHT...BUT HOLD OFF FOR NOW ON ADDING THEM INTO SUN/MON. TEMPS STILL LOOK TO REMAIN FAIRLY MILD. LONG TERM [TUE-FRI]... LONG RANGE MODELS OVERALL IN FAIRLY CLOSE AGREEMENT. THERMAL RIDGE WITH WARM-UP PEAKS OVER FA MID WEEK THEN GFS/ECMWF SAG BAROCLINIC BOUNDARY SOUTHWARD SECOND HALF OF WORK WEEK WHICH WILL BRING TEMPERATURES BACK (AT LEAST TEMPORARILY) TO AT OR BELOW SEASONAL AVERAGES. SOME LIGHT PCPN ALONG BAROCLINIC RIBBON SECOND HALF OF WORK WEEK BUT AT THIS POINT NOT SIGNIFICANT ENOUGH TO WARRANT POPS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 948 PM CST FRI JAN 16 2009 .UPDATE... LOWER CLOUDS ARE CONFINED TO FAR SOUTHEAST OKLAHOMA AND EXPECT ANY REDEVELOPMENT WILL BE ACROSS SC/SE OK OVERNIGHT PER RUC RH FIELDS. APPEARS 00Z NAM IS OVERDONE WITH HUMIDITY AROUND 9H. WITH WINDS STAYING IN THE 10 TO 20 MPH RANGE OVERNIGHT...TEMPS WILL ONLY LOWER A FEW MORE DEGREES WITH INCREASING TEMPS ACROSS N TX SOUTHWEST OKLAHOMA AS HIGHER DEWPOINTS ADVECT NORTHWARD. 00Z NAM ALSO BRINGS A CANADIAN HIGH SOUTHWARD LATE SUNDAY INTO MONDAY. SOURCE REGION OF AIR IS MUCH WARMER THAN A WEEK AGO AS FRIGID AIR IS MAINLY OVER EASTERN THIRD OF CANADA. HOWEVER AIRMASS MAY BE COOL ENOUGH TO KEEP SOME AREAS IN THE MID TO UPPER 40S. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 28 56 31 55 / 0 0 0 0 HOBART OK 26 58 30 59 / 0 0 0 0 WICHITA FALLS TX 29 61 31 61 / 0 0 0 0 GAGE OK 24 58 25 60 / 0 0 0 0 PONCA CITY OK 24 52 24 51 / 0 0 0 0 DURANT OK 27 58 35 57 / 0 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ SIX ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1135 AM CST THU JAN 15 2009 .AVIATION... UPSLOPE FLOW OVER NORTHWEST OKLAHOMA WILL HELP MAINTAIN MVFR CEILINGS EARLY THIS AFTERNOON... BUT DAYTIME HEATING SHOULD ERODE THIS CLOUD AREA FROM THE SOUTH. A FEW SNOW FLURRIES MAY ALSO OCCUR ACROSS NORTHERN OKLAHOMA... BUT NO SIGNIFICANT RESTRICTIONS TO VISIBILITY ARE EXPECTED. AS LOW-LEVEL FLOW TURNS FROM NORTHEAST TO SOUTHWEST OVERNIGHT... LOW-LEVEL MOISTURE OVER TEXAS WILL BE BROUGHT NORTH... AND MVFR CEILINGS ARE PROBABLE TOMORROW MORNING IN THE KSPS AREA. && .PREV DISCUSSION... /ISSUED 1120 AM CST THU JAN 15 2009/ UPDATE... WILL SEND AN UPDATE TO LOWER TEMPS ACROSS NORTHERN HALF OF AREA TODAY AS CLOUDS WILL REMAIN MORE PERSISTANT LIMITING ANY KIND OF WARMING THERE. OTHERWISE A FEW FLURRIES WILL CONT INTO THE AFTN ACROSS PARTS OF CENTRAL AND NORTHERN OK. 30 -------------------------------------------------- 513 AM CST THU JAN 15 2009 AVIATION...LIGHT SNOW WITH IFR CEILINGS OBSERVED IN KANSAS...AND SIMILAR CONDITIONS COULD BRIEFLY APPEAR AT KPNC BEFORE IMPROVING LATE THIS MORNING. USED RUC AND NAM HUMIDITY AT 925-850MB TO PROJECT IN TIME THE DEVELOPING MVFR CEILINGS AT KGAG-KWWR...WHILE KEEPING THE DECK SCATTERED AT KOUN-KOKC. WILL HAVE TO MONITOR CEILINGS THROUGH THE MID AFTERNOON...BUT CONDITIONS SHOULD IMPROVE BY EVENING WITH SUBSIDENCE AT MID LEVELS. PREV DISCUSSION... /ISSUED 418 AM CST THU JAN 15 2009/ DISCUSSION...RADAR MOSAIC THIS MORNING SHOWED A WIDE BAND OF LIGHT SNOW FROM KANSAS INTO NORTHERN OKLAHOMA. UPPER AIR DATA SHOWED THIS BAND CENTERED WITHIN A 700-500 MB FRONTAL ZONE WITH A LARGE AND LOW AMPLITUDE TROUGH UPSTREAM FROM THE PRECIPITATION. THIS MAKES THE SITUATION RELATIVELY CLEAR CUT...AS THE SNOW SHOULD PROGRESS ALONG AHEAD OF THE TROUGH...AND DIMINISH AFTER IT SWINGS THROUGH. BASED ON THE GFS FORECAST OF 700MB LIFT...WHICH MATCHES WELL WITH RADAR AND SATELLITE TRENDS...WE WILL PLACE THE BEST CHANCE FOR MEASURABLE SNOW IN NORTH CENTRAL OKLAHOMA THROUGH MIDDAY...DECREASING TO FLURRIES IN THE AFTERNOON. UP TO A HALF INCH OF SNOW MAY FALL IN THE MORNING TO THE NORTH OF AN ALVA TO STILLWATER LINE. WE EXPECT THE MORE SIGNIFICANT REDUCTION TO VISIBILITY AND CEILINGS TO REMAIN IN KANSAS...BUT A BRIEF PERIOD OF MORE SUBSTANTIAL SNOW COULD OCCUR JUST THIS SIDE OF THE OKLAHOMA BORDER. MEANWHILE...WIND CHILLS ARE NOTEWORTHY THIS MORNING...WITH SINGLE DIGITS OVER A MAJORITY OF OUR OKLAHOMA COUNTIES...AND SOME ZERO DEGREE READINGS IN THE NORTH. THE FORECAST GRIDS TAKE THE PONCA CITY AREA DOWN TO -5 WIND CHILL THIS MORNING FOR A SHORT TIME...BUT WITH WIND SPEEDS DECREASING...WE WILL CONTINUE TO GET THE MESSAGE OUT THROUGH SHORT TERM TEXT AND GRAPHICAL FORECASTS RATHER THAN ISSUE AN ADVISORY. WE WILL HAVE TO WATCH FOR THIS PROBLEM AGAIN FRIDAY MORNING...THOUGH...WHEN SOUTHERLY RETURN. WE UNDERCUT MOS GUIDANCE FOR THURSDAY NIGHT/FRIDAY MORNING LOW TEMPERATURES...BASED ON A RELATIVE LULL IN MID LEVEL CLOUDS THIS EVENING...AND AN AXIS OF LIGHT WINDS THAT IS NOW FORECAST TO EXTEND SOUTHWESTWARD FROM THE MAIN HIGH PRESSURE CIRCULATION OVER MISSOURI AND ARKANSAS. CLOUDS WILL MOVE BACK INTO THE NORTH LATE IN THE NIGHT...AND TEMPERATURES THERE MAY RISE TOWARD MORNING...BUT ALONG THE RED RIVER...A FULL NIGHT OF RADIATION...ALONG WITH THE ARRIVAL OF THE RIDGE AXIS...MAY YIELD LOWS APPROACHING SINGLE DIGITS. THROUGH ALL OF THIS...THERE IS VERY GOOD MODEL AGREEMENT ON THE LARGE SCALE...AND THE 00Z GFS WAS THE MODEL OF CHOICE. THIS LATEST DUMP OF COLD AIR HAS CLEANED OUT THE BEST OF WHAT THE ARCTIC HAD TO OFFER...SO IT WILL TAKE SOME TIME TO BUILD UP AGAIN. IN THE MEANTIME...WE EXPECT A SLOW EASTWARD PROGRESSION OF THE LONGWAVE PATTERN...WHICH WILL BRING UPPER RIDGING AND RISING TEMPERATURES FROM SATURDAY THROUGH THE MIDDLE OF NEXT WEEK. THE MODELS THEN BREAK DOWN THE RIDGE WITH ONE PACIFIC TROUGH THAT WILL CROSS THE PLAINS LATE NEXT WEEK. UNFORTUNATELY...MOISTURE RETURN IS LIKELY TO BE INSUFFICIENT FOR ANY SUBSTANTIAL RAINFALL...AND THE RIDGE IS FORECAST TO REBUILD OVER THE GULF OF ALASKA...WHICH SHOULD PLUNGE US BACK INTO COOL AND DRY NORTHWESTERLY FLOW. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 25 11 40 31 / 20 0 0 0 HOBART OK 27 12 47 27 / 10 0 0 0 WICHITA FALLS TX 36 14 46 30 / 0 0 0 0 GAGE OK 21 14 51 24 / 20 0 0 0 PONCA CITY OK 16 9 39 25 / 40 10 0 0 DURANT OK 36 11 39 30 / 10 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 30/23/23 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1120 AM CST THU JAN 15 2009 .UPDATE... WILL SEND AN UPDATE TO LOWER TEMPS ACROSS NORTHERN HALF OF AREA TODAY AS CLOUDS WILL REMAIN MORE PERSISTANT LIMITING ANY KIND OF WARMING THERE. OTHERWISE A FEW FLURRIES WILL CONT INTO THE AFTN ACROSS PARTS OF CENTRAL AND NORTHERN OK. 30 -------------------------------------------------- 513 AM CST THU JAN 15 2009 .AVIATION...LIGHT SNOW WITH IFR CEILINGS OBSERVED IN KANSAS...AND SIMILAR CONDITIONS COULD BRIEFLY APPEAR AT KPNC BEFORE IMPROVING LATE THIS MORNING. USED RUC AND NAM HUMIDITY AT 925-850MB TO PROJECT IN TIME THE DEVELOPING MVFR CEILINGS AT KGAG-KWWR...WHILE KEEPING THE DECK SCATTERED AT KOUN-KOKC. WILL HAVE TO MONITOR CEILINGS THROUGH THE MID AFTERNOON...BUT CONDITIONS SHOULD IMPROVE BY EVENING WITH SUBSIDENCE AT MID LEVELS. && .PREV DISCUSSION... /ISSUED 418 AM CST THU JAN 15 2009/ DISCUSSION...RADAR MOSAIC THIS MORNING SHOWED A WIDE BAND OF LIGHT SNOW FROM KANSAS INTO NORTHERN OKLAHOMA. UPPER AIR DATA SHOWED THIS BAND CENTERED WITHIN A 700-500 MB FRONTAL ZONE WITH A LARGE AND LOW AMPLITUDE TROUGH UPSTREAM FROM THE PRECIPITATION. THIS MAKES THE SITUATION RELATIVELY CLEAR CUT...AS THE SNOW SHOULD PROGRESS ALONG AHEAD OF THE TROUGH...AND DIMINISH AFTER IT SWINGS THROUGH. BASED ON THE GFS FORECAST OF 700MB LIFT...WHICH MATCHES WELL WITH RADAR AND SATELLITE TRENDS...WE WILL PLACE THE BEST CHANCE FOR MEASURABLE SNOW IN NORTH CENTRAL OKLAHOMA THROUGH MIDDAY...DECREASING TO FLURRIES IN THE AFTERNOON. UP TO A HALF INCH OF SNOW MAY FALL IN THE MORNING TO THE NORTH OF AN ALVA TO STILLWATER LINE. WE EXPECT THE MORE SIGNIFICANT REDUCTION TO VISIBILITY AND CEILINGS TO REMAIN IN KANSAS...BUT A BRIEF PERIOD OF MORE SUBSTANTIAL SNOW COULD OCCUR JUST THIS SIDE OF THE OKLAHOMA BORDER. MEANWHILE...WIND CHILLS ARE NOTEWORTHY THIS MORNING...WITH SINGLE DIGITS OVER A MAJORITY OF OUR OKLAHOMA COUNTIES...AND SOME ZERO DEGREE READINGS IN THE NORTH. THE FORECAST GRIDS TAKE THE PONCA CITY AREA DOWN TO -5 WIND CHILL THIS MORNING FOR A SHORT TIME...BUT WITH WIND SPEEDS DECREASING...WE WILL CONTINUE TO GET THE MESSAGE OUT THROUGH SHORT TERM TEXT AND GRAPHICAL FORECASTS RATHER THAN ISSUE AN ADVISORY. WE WILL HAVE TO WATCH FOR THIS PROBLEM AGAIN FRIDAY MORNING...THOUGH...WHEN SOUTHERLY RETURN. WE UNDERCUT MOS GUIDANCE FOR THURSDAY NIGHT/FRIDAY MORNING LOW TEMPERATURES...BASED ON A RELATIVE LULL IN MID LEVEL CLOUDS THIS EVENING...AND AN AXIS OF LIGHT WINDS THAT IS NOW FORECAST TO EXTEND SOUTHWESTWARD FROM THE MAIN HIGH PRESSURE CIRCULATION OVER MISSOURI AND ARKANSAS. CLOUDS WILL MOVE BACK INTO THE NORTH LATE IN THE NIGHT...AND TEMPERATURES THERE MAY RISE TOWARD MORNING...BUT ALONG THE RED RIVER...A FULL NIGHT OF RADIATION...ALONG WITH THE ARRIVAL OF THE RIDGE AXIS...MAY YIELD LOWS APPROACHING SINGLE DIGITS. THROUGH ALL OF THIS...THERE IS VERY GOOD MODEL AGREEMENT ON THE LARGE SCALE...AND THE 00Z GFS WAS THE MODEL OF CHOICE. THIS LATEST DUMP OF COLD AIR HAS CLEANED OUT THE BEST OF WHAT THE ARCTIC HAD TO OFFER...SO IT WILL TAKE SOME TIME TO BUILD UP AGAIN. IN THE MEANTIME...WE EXPECT A SLOW EASTWARD PROGRESSION OF THE LONGWAVE PATTERN...WHICH WILL BRING UPPER RIDGING AND RISING TEMPERATURES FROM SATURDAY THROUGH THE MIDDLE OF NEXT WEEK. THE MODELS THEN BREAK DOWN THE RIDGE WITH ONE PACIFIC TROUGH THAT WILL CROSS THE PLAINS LATE NEXT WEEK. UNFORTUNATELY...MOISTURE RETURN IS LIKELY TO BE INSUFFICIENT FOR ANY SUBSTANTIAL RAINFALL...AND THE RIDGE IS FORECAST TO REBUILD OVER THE GULF OF ALASKA...WHICH SHOULD PLUNGE US BACK INTO COOL AND DRY NORTHWESTERLY FLOW. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 25 11 40 31 / 20 0 0 0 HOBART OK 32 12 47 27 / 10 0 0 0 WICHITA FALLS TX 36 14 46 30 / 0 0 0 0 GAGE OK 27 14 51 24 / 10 0 0 0 PONCA CITY OK 20 9 39 25 / 40 10 0 0 DURANT OK 34 11 39 30 / 10 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 02/22/22 BURKE ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 513 AM CST THU JAN 15 2009 .AVIATION...LIGHT SNOW WITH IFR CEILINGS OBSERVED IN KANSAS...AND SIMILAR CONDITIONS COULD BRIEFLY APPEAR AT KPNC BEFORE IMPROVING LATE THIS MORNING. USED RUC AND NAM HUMIDITY AT 925-850MB TO PROJECT IN TIME THE DEVELOPING MVFR CEILINGS AT KGAG-KWWR...WHILE KEEPING THE DECK SCATTERED AT KOUN-KOKC. WILL HAVE TO MONITOR CEILINGS THROUGH THE MID AFTERNOON...BUT CONDITIONS SHOULD IMPROVE BY EVENING WITH SUBSIDENCE AT MID LEVELS. && .PREV DISCUSSION... /ISSUED 418 AM CST THU JAN 15 2009/ DISCUSSION...RADAR MOSAIC THIS MORNING SHOWED A WIDE BAND OF LIGHT SNOW FROM KANSAS INTO NORTHERN OKLAHOMA. UPPER AIR DATA SHOWED THIS BAND CENTERED WITHIN A 700-500 MB FRONTAL ZONE WITH A LARGE AND LOW AMPLITUDE TROUGH UPSTREAM FROM THE PRECIPITATION. THIS MAKES THE SITUATION RELATIVELY CLEAR CUT...AS THE SNOW SHOULD PROGRESS ALONG AHEAD OF THE TROUGH...AND DIMINISH AFTER IT SWINGS THROUGH. BASED ON THE GFS FORECAST OF 700MB LIFT...WHICH MATCHES WELL WITH RADAR AND SATELLITE TRENDS...WE WILL PLACE THE BEST CHANCE FOR MEASURABLE SNOW IN NORTH CENTRAL OKLAHOMA THROUGH MIDDAY...DECREASING TO FLURRIES IN THE AFTERNOON. UP TO A HALF INCH OF SNOW MAY FALL IN THE MORNING TO THE NORTH OF AN ALVA TO STILLWATER LINE. WE EXPECT THE MORE SIGNIFICANT REDUCTION TO VISIBILITY AND CEILINGS TO REMAIN IN KANSAS...BUT A BRIEF PERIOD OF MORE SUBSTANTIAL SNOW COULD OCCUR JUST THIS SIDE OF THE OKLAHOMA BORDER. MEANWHILE...WIND CHILLS ARE NOTEWORTHY THIS MORNING...WITH SINGLE DIGITS OVER A MAJORITY OF OUR OKLAHOMA COUNTIES...AND SOME ZERO DEGREE READINGS IN THE NORTH. THE FORECAST GRIDS TAKE THE PONCA CITY AREA DOWN TO -5 WIND CHILL THIS MORNING FOR A SHORT TIME...BUT WITH WIND SPEEDS DECREASING...WE WILL CONTINUE TO GET THE MESSAGE OUT THROUGH SHORT TERM TEXT AND GRAPHICAL FORECASTS RATHER THAN ISSUE AN ADVISORY. WE WILL HAVE TO WATCH FOR THIS PROBLEM AGAIN FRIDAY MORNING...THOUGH...WHEN SOUTHERLY RETURN. WE UNDERCUT MOS GUIDANCE FOR THURSDAY NIGHT/FRIDAY MORNING LOW TEMPERATURES...BASED ON A RELATIVE LULL IN MID LEVEL CLOUDS THIS EVENING...AND AN AXIS OF LIGHT WINDS THAT IS NOW FORECAST TO EXTEND SOUTHWESTWARD FROM THE MAIN HIGH PRESSURE CIRCULATION OVER MISSOURI AND ARKANSAS. CLOUDS WILL MOVE BACK INTO THE NORTH LATE IN THE NIGHT...AND TEMPERATURES THERE MAY RISE TOWARD MORNING...BUT ALONG THE RED RIVER...A FULL NIGHT OF RADIATION...ALONG WITH THE ARRIVAL OF THE RIDGE AXIS...MAY YIELD LOWS APPROACHING SINGLE DIGITS. THROUGH ALL OF THIS...THERE IS VERY GOOD MODEL AGREEMENT ON THE LARGE SCALE...AND THE 00Z GFS WAS THE MODEL OF CHOICE. THIS LATEST DUMP OF COLD AIR HAS CLEANED OUT THE BEST OF WHAT THE ARCTIC HAD TO OFFER...SO IT WILL TAKE SOME TIME TO BUILD UP AGAIN. IN THE MEANTIME...WE EXPECT A SLOW EASTWARD PROGRESSION OF THE LONGWAVE PATTERN...WHICH WILL BRING UPPER RIDGING AND RISING TEMPERATURES FROM SATURDAY THROUGH THE MIDDLE OF NEXT WEEK. THE MODELS THEN BREAK DOWN THE RIDGE WITH ONE PACIFIC TROUGH THAT WILL CROSS THE PLAINS LATE NEXT WEEK. UNFORTUNATELY...MOISTURE RETURN IS LIKELY TO BE INSUFFICIENT FOR ANY SUBSTANTIAL RAINFALL...AND THE RIDGE IS FORECAST TO REBUILD OVER THE GULF OF ALASKA...WHICH SHOULD PLUNGE US BACK INTO COOL AND DRY NORTHWESTERLY FLOW. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 25 11 40 31 / 20 0 0 0 HOBART OK 32 12 47 27 / 10 0 0 0 WICHITA FALLS TX 36 14 46 30 / 0 0 0 0 GAGE OK 27 14 51 24 / 10 0 0 0 PONCA CITY OK 20 9 39 25 / 40 10 0 0 DURANT OK 34 11 39 30 / 10 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 02/22/22 BURKE ok AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 1208 PM CST THU JAN 15 2009 .DISCUSSION...TEMPERATURES CONTINUE TO RISE SO SENT ANOTHER UPDATE FOR TODAY`S HIGH TEMPERATURES. NEW SET OF GRIDDED AND TEXT PRODUCTS ISSUED. && .AVIATION...ONLY PLACE THAT CIGS WILL BELOW MVFR WILL BE AT KLRD AND THAT WILL BE ROUGHLY BETWEEN 09Z AND 15Z...AND IN AREAS OF RAIN OR DRIZZLE AFTER 02Z. OTHERWISE OUTSIDE OF KLRD...CIGS AOA 4000 FEET WITH NO OTHER ISSUES EXCEPT WINDS WILL EVENTUALLY PICK UP TONIGHT ONCE THE COLDER AIR GETS HERE. && .PREV DISCUSSION... /ISSUED 1006 AM CST THU JAN 15 2009/ UPDATE...CLOUDS AND BETTER COLD AIR ADVECTION ARE TAKING THEIR TIME GETTING INTO EASTERN PORTIONS OF THE AREA. THUS...RAISED TEMPERATURES FOR TODAY. ALSO...BASED ON NEW NAM AND QUICK LOOK AT AVAILABLE NEW GFS...WENT A BIT MORE OPTIMISTICALLY ON CLOUD COVER OVER THE NORTHEASTERN SECTIONS TODAY AND ESPECIALLY TONIGHT...SINCE 12Z GFS IS NOW SHOWING BETTER 850 MB MOISTURE PUSHING WESTWARD LIKE THE NAM HAS BEEN DOING. FOR NOW...REMAINDER OF FORECAST UNCHANGED AND PRODUCTS HAVE BEEN SENT OUT. MARINE...MAINTAINED SCA AS-IS...ALTHOUGH NAM IS SHOWING A SLOWER INCREASE THAN PREVIOUSLY INDICATED. HOWEVER...RUC 13 IS SHOWING BETTER WINDS WITH WINDS COMING UP ABOUT AS PREVIOUSLY FORECAST SO FOR NOW WILL MAINTAIN SCA AS-IS. WINDS WILL PICK UP TONIGHT...BUT AT FIRST GLANCE WINDS MAY NOT BE AS STRONG...WILL LOOK AT MORE NEW MODEL DATA BEFORE MAKING THAT CHANGE AT THIS TIME. PREV DISCUSSION... /ISSUED 547 AM CST THU JAN 15 2009/ DISCUSSION...SEE AVIATION SECTION. AVIATION...ALTHOUGH VFR CONDS PREVAIL...LOW CLOUD/FOG LOOP SHOWS STRATOCU LAYER AROUND 5 TO 6 KFT ADVANCING SLOWLY TO NORTH-NORTHEAST WITH ONLY THE MID COAST REGION IN GENERALLY CLEAR SKIES. EXPECT CEILINGS WILL LOWER OVER THE WESTERN BRUSH COUNTRY AS LOW LEVEL WARM AIR ADVECTION INCREASES OVER THIS AREA TODAY. MVFR CEILINGS WILL DEVELOP LATER THIS MORNING AND CONTINUE THROUGH TONIGHT ALONG WITH VERY LIGHT RAIN/LIGHT DRIZZLE PROVIDING MVFR VSBYS ALONG THE RIO GRANDE. ELSEWHERE...DO NOT EXPECT LOWER CEILINGS TO OCCUR UNTIL THE RE-ENFORCING SURGE OF HIGH PRESSURE ARRIVES FOR THIS EVENING...WITH MVFR CEILINGS DEVELOPING OVER THE COASTAL BEND BY 08-09Z FRIDAY. PATCHY FOG IN THE CLEAR SKIES WILL PROVIDE MVFR VSBYS NEAR VCT THIS MORNING. PREV DISCUSSION... /ISSUED 429 AM CST THU JAN 15 2009/ SHORT TERM (TODAY THROUGH FRIDAY)...LATEST SURFACE ANALYSIS SHOWS THE SECONDARY FRONT OVER CENTRAL TEXAS AT THIS TIME. LOOKING AT THE LATEST NAM/GFS LIFTED INDEX PROGS SHOW THE SECONDARY SURGE ARRIVING DURING THE AFTERNOON. A MOIST BOUNDARY LAYER HAS MOVED INTO THE SOUTHERN COASTAL BEND EARLY THIS MORNING WITH DEWPOINT TEMPERATURES IN THE LOWER 50S. TEMPTED TO GO WITH NAM GUIDANCE FOR MAX TEMPS TODAY BUT EXPECT CLOUDS WILL CONTINUE TO INCREASE AS NAM/GFS SHOW ISENTROPIC UPGLIDE IN THE 290-295K LAYER. CLOUDS WILL TAKE THE LONGEST TO REACH THE MID COAST REGION SO EXPECT TEMPS IN THE LOW 60S THERE BEFORE FRONT ARRIVES IN THE AFTERNOON. STRONGEST LOW LEVEL WARM AIR ADVECTION AND ISENTROPIC LIFT ABOVE THE SHALLOW COLD AIRMASS WILL REMAIN OVER THE FAR WEST PORTIONS OF THE BRUSH COUNTRY. A SLIGHT CHANCE FOR LIGHT RAIN OR LIGHT DRIZZLE WILL CONTINUE OVER THE BRUSH COUNTRY TONIGHT. BUT THE MODELS SHOW LOW LEVEL DRY AIR ARRIVING WITH THE COLD AIRMASS THAT MOVES IN FOR FRIDAY. WILL SHOW ONLY A SLIGHT CHANCE OF LIGHT RAIN ALONG THE RIO GRANDE FOR FRIDAY. LONG TERM (FRIDAY NIGHT THROUGH WEDNESDAY)...A TROF OF LOW PRESSURE WILL REMAIN ALONG THE COAST FRI NITE/SAT. LAST FEW MODEL SOLNS HAD BACKED OFF ON THE AMOUNT OF MOISTURE IN PLACE OR THE STRENGTH OF ISENTROPIC UPGLIDE...HOWEVER THE LATEST SOLNS ARE A TAD HIGHER WITH MOISTURE/POPS FOR FRI NITE AND AGAIN SAT NITE TIME FRAME. DID NOT GO AS HIGH AS THE MEX VALUES BUT MAINLY KEPT A SLIGHT CHC OF -RA ACROSS THE W CWA WITH A MENTION OF -DZ ACROSS THE W HALF OF THE CWA. DURING THE DAY SATURDAY THE MOISTURE DECREASES SOMEWHAT BUT CONT WITH A MENTION OF PATCHY DZ GIVEN SUFFICIENT ISENTROPIC UPGLIDE. BY SAT NITE THE GFS AND TO A LESSER EXTENT THE ECMWF IS SHOWING SOME UPPER DYNAMICS COMING INTO PLAY AS THE UPPER JET SHIFTS FROM JUST S OF THE AREA TO JUST N...PLACING THE RRQ ACROSS THE CWA. UPPER DIFFLUENCE AND A SHORT WAVE ALSO COME INTO PLAY BUT ARE NOT VERY IMPRESSIVE. IN THE LOW LEVELS...CONVERGENCE INCREASES WITH THE APPROACH OF A COLD FRONT. THE QUESTION IS WILL THERE BE SUFFICIENT MOISTURE? FOR NOW KEPT A MENTION OF A SLIGHT CHC OF -SHRA`S ACROSS THE NE CWA THEN SHIFTING S AND E ON SUN AS THE FRONT PASSES THROUGH AND RIDGING TAKES PLACE IN THE MID/UPPER LEVELS. THIS BRINGS IN MUCH DRIER CONDITIONS LEADING TO MOSTLY SUNNY SKIES...SEASONABLE TEMPS THROUGH THE FIRST HALF OF NEXT WEEK. ONSHORE FLOW FINALLY BECOMES ESTABLISHED BY MID WEEK AS A SFC LOW DVLPS ACROSS THE TX PANHANDLE WHICH LEADS TO A WARMING TREND. MARINE...NORTHEAST WINDS WILL STEADILY INCREASE BY THIS AFTERNOON AS BUILDING HIGH PRESSURE OCCURS WITH THE ARRIVAL OF THE BACKDOOR COLD FRONT. WINDS WILL INCREASE TO STRONG OFFSHORE BY THIS EVENING AND CONTINUE THROUGH MUCH OF THE DAY FRIDAY. POSTED SCA FOR THE GULF WATERS FOR LATE THIS AFTERNOON THROUGH FRIDAY AFTERNOON. THE SCA FOR THE BAYS WAS INITIATED EARLY THIS EVENING AND ENDING AROUND NOON FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 70 45 51 47 65 / 10 10 10 10 10 VICTORIA 68 34 51 37 62 / 0 10 10 10 10 LAREDO 71 44 49 44 63 / 10 20 20 20 10 ALICE 72 42 49 42 65 / 10 10 10 10 10 ROCKPORT 66 43 51 47 64 / 0 10 10 10 10 COTULLA 68 41 47 41 60 / 10 10 10 20 10 KINGSVILLE 70 45 51 47 65 / 10 10 10 10 10 NAVY CORPUS 66 46 53 50 65 / 10 10 10 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 3 PM CST FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS BAFFIN BAY TO PORT ARANSAS OUT 20 NM...COASTAL WATERS PORT ARANSAS TO MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS BAFFIN BAY TO PORT ARANSAS 20 TO 60 NM... WATERS PORT ARANSAS TO MATAGORDA SHIP CHANNEL 20 TO 60 NM. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 12 PM CST FRIDAY FOR THE FOLLOWING ZONES: BAYS AND WATERWAYS FROM BAFFIN BAY TO PORT ARANSAS...BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT O`CONNOR. && $$ GW/86...SHORT TERM TM/95...LONG TERM tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 1006 AM CST THU JAN 15 2009 .UPDATE...CLOUDS AND BETTER COLD AIR ADVECTION ARE TAKING THEIR TIME GETTING INTO EASTERN PORTIONS OF THE AREA. THUS...RAISED TEMPERATURES FOR TODAY. ALSO...BASED ON NEW NAM AND QUICK LOOK AT AVAILABLE NEW GFS...WENT A BIT MORE OPTIMISTICALLY ON CLOUD COVER OVER THE NORTHEASTERN SECTIONS TODAY AND ESPECIALLY TONIGHT...SINCE 12Z GFS IS NOW SHOWING BETTER 850 MB MOISTURE PUSHING WESTWARD LIKE THE NAM HAS BEEN DOING. FOR NOW...REMAINDER OF FORECAST UNCHANGED AND PRODUCTS HAVE BEEN SENT OUT. && .MARINE...MAINTAINED SCA AS-IS...ALTHOUGH NAM IS SHOWING A SLOWER INCREASE THAN PREVIOUSLY INDICATED. HOWEVER...RUC 13 IS SHOWING BETTER WINDS WITH WINDS COMING UP ABOUT AS PREVIOUSLY FORECAST SO FOR NOW WILL MAINTAIN SCA AS-IS. WINDS WILL PICK UP TONIGHT...BUT AT FIRST GLANCE WINDS MAY NOT BE AS STRONG...WILL LOOK AT MORE NEW MODEL DATA BEFORE MAKING THAT CHANGE AT THIS TIME. && .PREV DISCUSSION... /ISSUED 547 AM CST THU JAN 15 2009/ DISCUSSION...SEE AVIATION SECTION. AVIATION...ALTHOUGH VFR CONDS PREVAIL...LOW CLOUD/FOG LOOP SHOWS STRATOCU LAYER AROUND 5 TO 6 KFT ADVANCING SLOWLY TO NORTH-NORTHEAST WITH ONLY THE MID COAST REGION IN GENERALLY CLEAR SKIES. EXPECT CEILINGS WILL LOWER OVER THE WESTERN BRUSH COUNTRY AS LOW LEVEL WARM AIR ADVECTION INCREASES OVER THIS AREA TODAY. MVFR CEILINGS WILL DEVELOP LATER THIS MORNING AND CONTINUE THROUGH TONIGHT ALONG WITH VERY LIGHT RAIN/LIGHT DRIZZLE PROVIDING MVFR VSBYS ALONG THE RIO GRANDE. ELSEWHERE...DO NOT EXPECT LOWER CEILINGS TO OCCUR UNTIL THE RE-ENFORCING SURGE OF HIGH PRESSURE ARRIVES FOR THIS EVENING...WITH MVFR CEILINGS DEVELOPING OVER THE COASTAL BEND BY 08-09Z FRIDAY. PATCHY FOG IN THE CLEAR SKIES WILL PROVIDE MVFR VSBYS NEAR VCT THIS MORNING. PREV DISCUSSION... /ISSUED 429 AM CST THU JAN 15 2009/ SHORT TERM (TODAY THROUGH FRIDAY)...LATEST SURFACE ANALYSIS SHOWS THE SECONDARY FRONT OVER CENTRAL TEXAS AT THIS TIME. LOOKING AT THE LATEST NAM/GFS LIFTED INDEX PROGS SHOW THE SECONDARY SURGE ARRIVING DURING THE AFTERNOON. A MOIST BOUNDARY LAYER HAS MOVED INTO THE SOUTHERN COASTAL BEND EARLY THIS MORNING WITH DEWPOINT TEMPERATURES IN THE LOWER 50S. TEMPTED TO GO WITH NAM GUIDANCE FOR MAX TEMPS TODAY BUT EXPECT CLOUDS WILL CONTINUE TO INCREASE AS NAM/GFS SHOW ISENTROPIC UPGLIDE IN THE 290-295K LAYER. CLOUDS WILL TAKE THE LONGEST TO REACH THE MID COAST REGION SO EXPECT TEMPS IN THE LOW 60S THERE BEFORE FRONT ARRIVES IN THE AFTERNOON. STRONGEST LOW LEVEL WARM AIR ADVECTION AND ISENTROPIC LIFT ABOVE THE SHALLOW COLD AIRMASS WILL REMAIN OVER THE FAR WEST PORTIONS OF THE BRUSH COUNTRY. A SLIGHT CHANCE FOR LIGHT RAIN OR LIGHT DRIZZLE WILL CONTINUE OVER THE BRUSH COUNTRY TONIGHT. BUT THE MODELS SHOW LOW LEVEL DRY AIR ARRIVING WITH THE COLD AIRMASS THAT MOVES IN FOR FRIDAY. WILL SHOW ONLY A SLIGHT CHANCE OF LIGHT RAIN ALONG THE RIO GRANDE FOR FRIDAY. LONG TERM (FRIDAY NIGHT THROUGH WEDNESDAY)...A TROF OF LOW PRESSURE WILL REMAIN ALONG THE COAST FRI NITE/SAT. LAST FEW MODEL SOLNS HAD BACKED OFF ON THE AMOUNT OF MOISTURE IN PLACE OR THE STRENGTH OF ISENTROPIC UPGLIDE...HOWEVER THE LATEST SOLNS ARE A TAD HIGHER WITH MOISTURE/POPS FOR FRI NITE AND AGAIN SAT NITE TIME FRAME. DID NOT GO AS HIGH AS THE MEX VALUES BUT MAINLY KEPT A SLIGHT CHC OF -RA ACROSS THE W CWA WITH A MENTION OF -DZ ACROSS THE W HALF OF THE CWA. DURING THE DAY SATURDAY THE MOISTURE DECREASES SOMEWHAT BUT CONT WITH A MENTION OF PATCHY DZ GIVEN SUFFICIENT ISENTROPIC UPGLIDE. BY SAT NITE THE GFS AND TO A LESSER EXTENT THE ECMWF IS SHOWING SOME UPPER DYNAMICS COMING INTO PLAY AS THE UPPER JET SHIFTS FROM JUST S OF THE AREA TO JUST N...PLACING THE RRQ ACROSS THE CWA. UPPER DIFFLUENCE AND A SHORT WAVE ALSO COME INTO PLAY BUT ARE NOT VERY IMPRESSIVE. IN THE LOW LEVELS...CONVERGENCE INCREASES WITH THE APPROACH OF A COLD FRONT. THE QUESTION IS WILL THERE BE SUFFICIENT MOISTURE? FOR NOW KEPT A MENTION OF A SLIGHT CHC OF -SHRA`S ACROSS THE NE CWA THEN SHIFTING S AND E ON SUN AS THE FRONT PASSES THROUGH AND RIDGING TAKES PLACE IN THE MID/UPPER LEVELS. THIS BRINGS IN MUCH DRIER CONDITIONS LEADING TO MOSTLY SUNNY SKIES...SEASONABLE TEMPS THROUGH THE FIRST HALF OF NEXT WEEK. ONSHORE FLOW FINALLY BECOMES ESTABLISHED BY MID WEEK AS A SFC LOW DVLPS ACROSS THE TX PANHANDLE WHICH LEADS TO A WARMING TREND. MARINE...NORTHEAST WINDS WILL STEADILY INCREASE BY THIS AFTERNOON AS BUILDING HIGH PRESSURE OCCURS WITH THE ARRIVAL OF THE BACKDOOR COLD FRONT. WINDS WILL INCREASE TO STRONG OFFSHORE BY THIS EVENING AND CONTINUE THROUGH MUCH OF THE DAY FRIDAY. POSTED SCA FOR THE GULF WATERS FOR LATE THIS AFTERNOON THROUGH FRIDAY AFTERNOON. THE SCA FOR THE BAYS WAS INITIATED EARLY THIS EVENING AND ENDING AROUND NOON FRIDAY. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 67 45 51 47 65 / 10 10 10 10 10 VICTORIA 62 34 51 37 62 / 0 10 10 10 10 LAREDO 65 44 49 44 63 / 10 20 20 20 10 ALICE 69 42 49 42 65 / 10 10 10 10 10 ROCKPORT 65 43 51 47 64 / 0 10 10 10 10 COTULLA 62 41 47 41 60 / 10 10 10 20 10 KINGSVILLE 70 45 51 47 65 / 10 10 10 10 10 NAVY CORPUS 66 46 53 50 65 / 10 10 10 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 3 PM CST FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS BAFFIN BAY TO PORT ARANSAS OUT 20 NM...COASTAL WATERS PORT ARANSAS TO MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS BAFFIN BAY TO PORT ARANSAS 20 TO 60 NM...WATERS PORT ARANSAS TO MATAGORDA SHIP CHANNEL 20 TO 60 NM. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 12 PM CST FRIDAY FOR THE FOLLOWING ZONES: BAYS AND WATERWAYS FROM BAFFIN BAY TO PORT ARANSAS...BAYS AND WATERWAYS FROM PORT ARANSAS TO PORT O`CONNOR. && $$ GW/86...SHORT TERM TM/95...LONG TERM tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 517 AM EST SAT JAN 17 2009 .SHORT TERM... TODAY THROUGH SUNDAY NIGHT. LITTLE DIFF IN DIAG MODEL OUTPUT THOUGH SOME PREFERENCE LIES WITH GFS WITH SHARPER MLVL TROF DVLPG ACRS LWR GRTLKS BY F60. SERIES OF STRONG SHORTWAVES PER WV IMAGERY WITH FIRST NOW INTO WI AND OTHERS DROPPING SOUTH THRU MANITOBA WITH 75KT JETLET PER RAOB SHOULD SERVE TO CARVE A HIGH AMP TROF FM LABRADOR SEA TO ERN OH BY MON AM. INITIAL WAVE WITH 35-45KT ORTHOGONAL FLOW TO I285K ISENT WITH TWO DISTINCT 3-3.5 G/KG POOLS SRN IL AND SRN MN/NWRN IA. FIRST OF WHICH SHOULD HELP TO MOISTEN LLVLS TO AID IN EXPANSION OF SNOW ASSOCD W/DESCENDING CLIPPER. PREFERENCE AGAIN LIES WITH GFS DIGGING SFC REFLECTION A BIT FURTHER SOUTH AND REMAINING CONSISTENT WITH ECWMF SUPPORT. QUESTIONS LIE WITH SOUTHERN EXTENT OF LOW QPF/SNOW AMOUNTS...THOUGH HAVE UPPED POPS AND BROUGHT MINOR ACCUMS FURTHER SOUTH...KEEPING TIGHT GRADIENT INTO FAR SWRN/SRN ZONES W/LOW CHC RANGE. QUESTIONABLE ICE NUCLEATION REMAINS ESPCLY OUT OF HIEST POP RGNS FOR AT LEAST SCT FZDZ TO OCCUR THIS AFTN/EARLY TONIGHT. GIVEN BREADTH OF COLD AIR AND ANTICIPATED CLOUDS/PRECIP HAVE LWRD TEMPS A FEW DEGREES TODAY. TREND OF LWRG CONTD FOR TONIGHT/SUN WHILST SHRINKING DIURNAL SWING. STRONG CAA TONIGHT RIDDING SUPERCOOLED DROPLETS CONCERNS FOR RMNDR OF SHORT TERM. SFC-8H CIRC INTO SRN ONT SUNDAY/SUNDAY NIGHT KEEPING CWA IN MOISTURE TRAPPED/CYCLONIC REGIME WITH VARIOUS WEAK SHORTWAVES FOR CONT CHC LIGHT SNOW...HIR IN LES REGION SPCLY LATER AS POTNL FOR A LK SUPERIOR CONNECTION DVLPS. && .LONG TERM... MONDAY THROUGH FRIDAY. REGION WILL BE FALLING INTO THE WAKE OF THE CLIPPER SYSTEM WITH LAKE EFFECT ATTEMPTING TO START UP AT THE START OF THE PERIOD. DELTA T`S LOOK TO BE IN THE MID TO UPR TEENS AND INVERSION HGTS STARTING AROUND 60OO FT BUT SLOWLY LOWERING WITH TIME. THESE FACTORS AND A RAPIDLY CHANGING PATTERN WITH ADVANCE OF ANOTHER CLIPPER MON WILL LIKELY KEEP SIG SNOWS FROM OCCURRING BUT STILL SHOULD GIVE PRECIP TO FAVORED LOCATIONS...EVEN WELL INLAND AND HAVE RAISED POPS ACCORDINGLY AND WITH EYE TOWARD BETTER COLLABORATION. FLOW WILL QUICKLY BACK TO MORE SOUTHERLY AS BITTER COLD AIR BEGINS TO DEPART THE AREA...BUT POSSIBLY ONLY FOR A SHORT TIME. ANOTHER WEAK SYSTEM WILL MOVE IN WITH A MON NIGHT/TUE CLIPPER BRINGING A CHANCE OF LIGHT SNOW...BUT SYSTEM LOOKS TO BE MSTR STARVED AND DOES NOT APPEAR TO POSE MUCH CONCERN AT THIS POINT. ONE PLUS NO MATTER WHAT...AFTERWARDS WILL BE THE START OF A PUSH OF WARMER AIR...AT LEAST WELL WARMER THAN WHAT WE HAVE SEEN PAST FEW DAYS. MODELS STILL SUGGESTING A BRIEF WARM UP TOWARDS FREEZING BY THURSDAY IN ADVANCE OF THE NEXT SYSTEM. LOOKS TO PASS MAINLY NORTH OF THE AREA WITH A COLD FRONT TRAILING THURS NGT INTO FRI. MAY BE A CHANCE OF SNOW WITH IT...BUT TOO EARLY TOO PIN DOWN THIS OR THE DEGREE OF COLD AIR BEHIND IT. NEEDLESS TO SAY...IF MODELS HOLD TRUE AT LEAST A BRIEF RETURN TO HIGHS IN THE TEENS AND MAYBE SINGLE DIGITS MAY OCCUR. && .AVIATION... PRIMARY FOCUS ON UPPING TIMING OF SNFL ARRIVAL SVRL HOURS AND INTRODUCING TEMPO IFR CONDS AT KSBN. ADVANCING MOISTURE ON I285K SFC ACRS WITH VFR SC ACRS MUCH OF IL TO HELP PRE-MOISTEN ENVIRONMENT ACRS NRN IND IN ADVANCE O CLIPPER SYSTEM DECENDING RAPIDLY SEWD FM THE NRN PLAINS. NAM WRF 4KM REFL AS WELL AS SREF/GFS/RUC ALL SUGGEST SN ON DOORSTEP OF KSBN BY 12 UTC. XTRMLY COLD AIRMASS TO QUICKLY SATURATE/CIGS LWR WITH TIME AND VSBYS AS WELL WITH FINE CRYSTAL FLAKES ANTICIPATED WITH DGZ CONFINED TO SUBCLOUD LYR. SLIGHT DELAY AND GNRLY IMPROVED CONDS AT KFWA ON SRN PERIPHERY OF MORE INTENSE SNWFL. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL WARNING UNTIL 7 AM EST /6 AM CST/ THIS MORNING FOR INZ003>009-012>018-020-022>027-032>034. MI...WIND CHILL WARNING UNTIL 7 AM EST THIS MORNING FOR MIZ077>081. OH...WIND CHILL WARNING UNTIL 7 AM EST THIS MORNING FOR OHZ001-002- 004-005-015-016-024-025. LM...SMALL CRAFT ADVISORY UNTIL 1 AM EST SUNDAY FOR LMZ043-046. && $$ SHORT TERM...MURPHY LONG TERM...FISHER AVIATION...MURPHY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 110 AM EST SAT JAN 17 2009 .AVIATION... PRIMARY FOCUS ON UPPING TIMING OF SNFL ARRIVAL SVRL HOURS AND INTRODUCING TEMPO IFR CONDS AT KSBN. ADVANCING MOISTURE ON I285K SFC ACRS WITH VFR SC ACRS MUCH OF IL TO HELP PRE-MOISTEN ENVIRONMENT ACRS NRN IND IN ADVANCE O CLIPPER SYSTEM DECENDING RAPIDLY SEWD FM THE NRN PLAINS. NAM WRF 4KM REFL AS WELL AS SREF/GFS/RUC ALL SUGGEST SN ON DOORSTEP OF KSBN BY 12 UTC. XTRMLY COLD AIRMASS TO QUICKLY SATURATE/CIGS LWR WITH TIME AND VSBYS AS WELL WITH FINE CRYSTAL FLAKES ANTICIPATED WITH DGZ CONFINED TO SUBCLOUD LYR. SLIGHT DELAY AND GNRLY IMPROVED CONDS AT KFWA ON SRN PERIPHERY OF MORE INTENSE SNWFL. && .UPDATE... GIVEN CONTINUED CRASHING TEMPERATURES...WILL NEED TO UPGRADE WIND CHILL ADVISORY TO WARNING AS FWA/GSH ALREADY HAVE WIND CHILLS AT -25F AS OF 7PM AND MORE LOCATIONS WILL SEE WIND CHILLS FALL TO BETWEEN -25 AND -35 TONIGHT. HAVE LOWERED TEMPS A FEW DEGREES MORE...GENERALLY BETWEEN -10 TO -15 WITH A FEW SITES LIKELY FALLING A LITTLE LOWER THAN THIS. UPDATED GRIDS/PRODUCTS ARE OUT. && .PREV DISCUSSION... /ISSUED 658 PM EST FRI JAN 16 2009/ UPDATE... UPDATE TO CUT TEMPERATURES THIS EVENING AS WE/LL HAVE SOME IDEAL RADIATIONAL COOLING CONDITIONS THROUGH THE FIRST HALF OF THE OVERNIGHT BEFORE INCREASING HIGH CLOUDS HELP TURN TEMPS AROUND AFTER MIDNIGHT. DEWPOINTS IN THE MINUS TEENS SUGGEST PLENTY OF ROOM TO DROP. RUC13 HAS THE BEST HANDLE ON THIS THIS EVENING BUT AM A LITTLE FEARFUL THAT IN SOME SPOTS IT MAY STILL BE TOO WARM. OVER MUCH OF THE AREA...THIS MEANS ANOTHER NIGHT OF -10 TO -15F. IN ADDITION...THE SOMEWHAT COLDER TEMPS SHOULD PROLONG ADV LEVEL WIND CHILLS TONIGHT SO HAVE EXTENDED THE WC ADVISORY THROUGH 12Z AND WILL HAVE TO WATCH TEMPS LATE THIS EVENING AS WE WILL BE NEAR WC WARNING CRITERIA FOR THE OVERNIGHT. PREV DISCUSSION... /ISSUED 336 PM EST FRI JAN 16 2009/ SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT MAIN FOCUS IN THE SHORT TERM IS TEMPS/WIND CHILLS TONIGHT AND SN/FZDZ CHANCES SAT INTO SAT NIGHT. WINDS DROPPING TO NEAR 5 KNOTS AND MAINLY CLEAR SKIES EARLY THIS EVENING WILL PROBABLY ALLOW TEMPS TO PLUMMET BACK TOWARDS -10F THIS EVENING. EXPECT SOME WARMING AFTER MIDNIGHT AS SOUTHWESTERLY LL FLOW DEVELOPS ON BACKSIDE OF 1040MB ARCTIC HIGH WHICH WILL SHIFT EASTWARD INTO THE CENTRAL APPS/MIDDLE ATLANTIC. THEREFORE...HAVE NON DIURNAL TEMPS TONIGHT WITH VALUES HOPEFULLY WARMING INTO THE SINGLE DIGITS ABV ZERO BY 12Z SAT. COLD TEMPS COMBINED WITH LIGHT SSW SFC WINDS WILL KEEP APPARENT TEMPS IN THE -15 TO -25F RANGE...SO WENT WITH A WIND CHILL ADVISORY FOR THE ENTIRE CWA THROUGH 09Z SATURDAY. SHORTWAVE CURRENTLY OVER NRN FRINGE OF HIGHLY AMPLIFIED EASTERN PAC/WESTERN NOAM RIDGE WILL RAPIDLY SLIDE SEWD INTO THE UPPER MIDWEST LATE TONIGHT...AND THE GREAT LAKES SATURDAY INTO SATURDAY NIGHT. FAVOR FARTHER NORTH AND DRIER NAM/SREF/ECMWF SOLUTIONS OVER THE GFS IN TRACKING ASSOCIATED SFC REFLECTION INTO CENTRAL LOWER MICHIGAN BY SATURDAY EVENING...AS THE NAM HAS PERFORMED BETTER FOR THE LAST SEVERAL CLIPPER EVENTS WHEN COMPARED TO THE GFS. WAA/ISENTROPIC UPGLIDE WITH 40-50KT CROSS ISOBARIC FLOW AND 2-3 G/KG MOISTURE SURGE OVER ARCTIC DOME DOES SUPPORT A BAND OF LIGHT/MODERATE SNOW PIVOTING EAST THROUGH AT LEAST FAR NORTHERN AREAS ON SATURDAY. BETTER CHANCES FOR DECENT SNOW ACCUMULATIONS IN THE 1-3 INCH RANGE APPEAR POSSIBLE IN THE COLDWATER/HILLSDALE AREAS CLOSER TO THE DEEPER MOISTURE AND BETTER DYNAMICS. MAYBE A COATING TO AN INCH IN CENTRAL AREAS WITH LITTLE IF ANY ACCUMULATION IN THE SOUTHWEST. ADDED FREEZING DRIZZLE MENTION TO WESTERN/SOUTHERN AREAS SAT AFTN/EVE AS NAM FCST SOUNDINGS CONSISTENT IN SHOWING LACK OF MOISTURE IN THE ICE PRODUCTION ZONE WITH LL MOISTURE TRAPPED UNDER A LOWERING INVERSION. SLICK SPOTS ON AREA ROADS WILL BE POSSIBLE IF THIS MATERIALIZES. OTHERWISE... IT WILL FEEL BALMY OUT BY TOMORROW AFTERNOON WITH HIGHS RECOVERING ALL THE WAY BACK INTO THE 20S. LARGE SCALE LIFT PER 5-3H Q-VECTOR CONVERGENCE AND DIFF PVA AHEAD OF H5 TROUGH AXIS SHIFTS EAST BY 00Z SUN WITH JUST LINGERING LIGHT SNOW SHOWERS/FLURRIES/PATCHY FZDZ SAT EVE. CAA BEHIND SYSTEM WILL ALLOW FOR LAKE EFFECT SNOW SHOWERS TO DEVELOP ACROSS THE FAR NW LATE SATURDAY NIGHT. CONTINUED WITH LIKELY POPS IN THESE AREAS 06-12Z SUN. DELTA T/S OF 15-18 AND SATURATION WITHIN THE DGZ INDICATE POTENTIAL FOR SOME SNOW ACCUMULATION WITH LAKE EFFECT. HOWEVER...INVERSION NEAR 5KFT AND UNFAVORABLE 280/290 DEGREE FETCH DO NOT FAVOR ACCUMS ABOVE 2 INCHES. LONG TERM... SUNDAY THROUGH FRIDAY... LONG TERM WILL SEE CHANGES TO LARGE SCALE UPPER AIR PATTERN OVER THE CONUS AS WESTERN RIDGE BEGINS TO BREAK DOWN AS STRONG PACIFIC ENERGY UNDERCUTS IT. TROUGHINESS OVER THE EASTERN CONUS EXPECTED TO PERSIST AS NORTHERN BRANCH OF UPPER JET REMAINS DOMINANT AND CONTINUES TO DIVE INTO THE GREAT LAKES. ECMWF AND GFS HAVE SIGNIFICANTLY DIFFERENT SOLUTIONS IN HOW THIS PATTERN WILL EVOLVE AND THEREFORE A LARGE DEGREE OF UNCERTAINTY IN THE LATTER PART OF THE LONG TERM GRIDS. BEGINNING OF PERIOD WILL SEE CLIPPER SYSTEM CROSSING AND EXITING THE AREA WITH CHANCES FOR LIGHT SNOW SUNDAY. LAKE EFFECT POTENTIAL CONTINUES BEHIND CLIPPER SUNDAY AFTERNOON AND SUNDAY NIGHT...INTO MONDAY MORNING. THIS IS AN INTERESTING SETUP AND HAS POTENTIAL FOR A DECENT SNOW EVENT ASSUMING MOISTURE REMAINS IN PLACE. LIMITING FACTOR WILL BE TRANSITORY NATURE OF BAND AND DEPTH OF MOISTURE. DUE TO LIMITING FACTORS AND QUESTIONS ON BAND PLACEMENT HAVE CONTINUED WITH HIGH CHANCE POPS RATHER THAN LIKELY OR CATEGORICAL. LATEST NAM INDICATING EVOLUTION INTO SINGLE BAND INTO FAR WESTERN COUNTIES BY MONDAY MORNING. NAM HAS ALSO STRUGGLED WITH RECENT LAKE EVENTS IN THESE PERIODS SO STILL SOME DOUBT. STAYED CLOSE TO A BLEND OF PREVIOUS GRIDS AND HPC FOR MIDDLE TO LATE PART OF LONG TERM GIVEN MODEL DIFFERENCES. ECMWF HAS BEEN MODEL OF CHOICE MOST OF WINTER AND IT IS NOT AS AGGRESSIVE WITH MID WEEK WARM UP AS GFS...WHICH SHOWS 850MB TEMPS WELL ABOVE CLIMO FOR MID JANUARY. HAVE DOUBTS AT THIS TIME ON SUCH A PRONOUNCED WARM UP GIVEN STRONG ARCTIC AIR MASS IN PLACE AND DEEP SNOW PACK THAT EXISTS. PREFER COOLER ECMWF. GRIDS AND HPC IN THE MIDDLE AND PREFER TO KEEP IT THAT WAY UNTIL CLEAR PATTERN EVOLVES. ECMWF SHOWING ANOTHER COLD ARCTIC FRONT LATE IN THE PERIOD. GFS DEVELOPING A RATHER STRONG CYCLONE BY DAY 7. AGAIN WILL STAY IN MIDDLE GROUND AND SIDE WITH HPC FOR COLLABORATION GIVEN WIDE VARIETY OF POSSIBLE SOLUTIONS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL WARNING UNTIL 7 AM EST /6 AM CST/ SATURDAY FOR INZ003>009-012>018-020-022>027-032>034. MI...WIND CHILL WARNING UNTIL 7 AM EST SATURDAY FOR MIZ077>081. OH...WIND CHILL WARNING UNTIL 7 AM EST SATURDAY FOR OHZ001-002-004- 005-015-016-024-025. LM...NONE. && $$ SHORT TERM...STEINWEDEL LONG TERM...LASHLEY AVIATION...MURPHY UPDATE...ARNOTT in AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1233 AM EST SAT JAN 17 2009 UPDATED AVIATION DISCUSSION FOR 06Z TAF ISSUANCE .SYNOPSIS... WATER VAPOR IMAGERY AND RUC ANALYSIS CONTINUE TO SHOW AN AMPLIFIED PATTERN ACROSS NAMERICA WITH A PRONOUNCED RIDGE OVER THE W AND A DEEP TROF OVER THE E. A WELL DEFINED SHORTWAVE TROF WAS DROPPING SE THRU ALBERTA/SASKATCHEWAN/MANITOBA. IN THE SHORT TERM...THIS WILL BE THE MAIN FEATURE OF INTEREST AS IT MOVES INTO THE UPPER MISSISSIPPI VALLEY/GREAT LAKES REGION SAT. ARCTIC AIRMASS OVER THE UPPER LAKES REGION IS BEGINNING TO EASE UNDER DEVELOPING WAA PATTERN AHEAD OF SHORTWAVE TROF. THIS HAS ALLOWED TEMPS TO RISE INTO THE SINGLE DIGITS ABOVE ZERO ACROSS THE FCST AREA THIS AFTN. VIS SATELLITE IMAGERY AND KMQT RADAR SHOW DIMINISHING LES SHIFTING UNDER BACKING LOW-LEVEL WINDS. LAST OF THE LES IS CURRENTLY AFFECTING THE TIP OF THE KEWEENAW PENINSULA AND AREAS FROM PICTURED ROCKS ACROSS NRN LUCE COUNTY. HIGH RES POLAR ORBITER IMAGE TODAY SHOWS SIGNIFICANT ICE FORMATION HAS OCCURRED ACROSS LAKE SUPERIOR OVER THE LAST COUPLE OF DAYS. BKN ICE EXTENDS WNW FROM THE PORCUPINE MTNS TO THE MN SHORE. MORE ICE EXTENDS FROM THE MN/ONTARIO SHORE TO ISLE ROYALE...AND A LARGE AREA OF ICE HAS FORMED W OF A LINE ROUGHLY FROM SHOT PT TO MANITOU ISLAND. && .SHORT TERM (TONIGHT THRU SAT AFTN)... LAST OF THE LES OVER THE TIP OF THE KEWEENAW AND FROM AROUND GRAND MARAIS EWD WILL END THIS EVENING AS WINDS CONTINUE TO BACK AHEAD OF APPROACHING SHORTWAVE TROF AND ASSOCIATED SFC TROF/LOW PRES. ACCUMULATIONS WILL BE WELL UNDER 1 INCH. BEFORE CLOUDS INCREASE/THICKEN FROM THE NW...TEMPS MAY CRASH UNDER LIGHT WINDS. FAVORED THE LOW END OF MOS GUIDANCE WITH SINGLE DIGITS BLO ZERO EXPECTED OVER MUCH OF THE FCST AREA. WILL NEED TO MONITOR TRENDS OVER THE ERN FCST AREA THIS EVENING AS THAT AREA HAS BEST POTENTIAL TO FALL BLO FCST MINS. ATTENTION THEN TURNS TO APPROACHING SHORTWAVE TROF. FAIRLY STRONG ISENTROPIC ASCENT PATTERN DEVELOPS LATE TONIGHT/SAT MORNING. MIXING RATIOS OF 2G/KG ARE AVBL ON THE 285K SFC (AROUND 700MB). WITH 6-9HRS OF LIFT...ACCUMULATIONS SHOULD RANGE FROM 2-3INCHES BY THE TIME SNOW DIMINISHES SAT. HOWEVER...GFS/NAM FCST SOUNDINGS SHOW A DEEP LAYER OF TEMPS FAVORABLE FOR DENDRITIC SNOW GROWTH FROM NEAR THE SFC TO AROUND 10KFT OR SO. THUS...SNOW TO WATER RATIOS MAY BE QUITE HIGH. WHILE AN ADVY LOOKS MARGINAL ATTM FOR THE FCST AREA...IT APPEARS SYSTEM WILL BE BECOMING BETTER ORGANIZED WITH MORE FOCUSED FORCING AS IT TRACKS SE. HAVE THUS OPTED FOR AN ADVY ACROSS THE S FROM IRON COUNTY TO SRN SCHOOLCRAFT FOR ROUGHLY 3-5 INCHES OF SNOW. MORE CHALLENGING PART OF THE FCST IS WHAT MAY TRANSPIRE CLOSE TO LAKE MICHIGAN. ALTHOUGH EACH MODEL SHOWS IMPORTANT DETAIL DIFFERENCES WITH LOW-LEVEL WINDS ACROSS NRN LAKE MICHIGAN...CONSENSUS IS THAT WINDS WILL BE FAVORABLE FOR AT LEAST SOME ENHANCEMENT OVER SE DELTA/SRN SCHOOLCRAFT. HOWEVER...HAVE CONCERNS THAT SIGNIFICANT ENHANCEMENT/HVY SNOW ACCUMULATIONS MAY OCCUR SOMEWHERE IN THAT AREA GIVEN THE DEEP DENDRITIC SNOW GROWTH ZONE AND POTENTIAL FOR SHARP CONVERGENCE TO SET UP FOR A TIME UNDER SFC TROF THAT WILL BE DEVELOPING SOUTHEASTWARD ACROSS NRN LAKE MICHIGAN. FOR NOW...INCLUDED THE HIGHEST SNOW ACCUMULATIONS AROUND 6 INCHES ACROSS SE DELTA/SRN SCHOOLCRAFT...BUT POTENTIAL IS THERE FOR SIGNIFICANTLY MORE IF WIND FIELDS SET UP JUST RIGHT. WILL NEED TO MONITOR MODEL RUNS TONIGHT TO SEE IF A TREND DEVELOPS FOR MORE FOCUSED SRLY CONVERGENCE IN THAT AREA. .LONG TERM (SATURDAY NIGHT THROUGH NEXT FRIDAY)... POSTIVE PNA PATTERN WITH A RIDGE OVR WESTERN NOAM AND TROUGH OVR EASTERN NOAM CONTINUES THROUGH NEXT WEEK. RIDGE/WARMER AIR OVR WEST CONUS DOES EDGE INTO UPR MISSISSIPPI RIVER VALLEY AND WESTERN GREAT LAKES EARLY NEXT WEEK. BUT...THE BRIEF WARM UP IS QUICKLY REPLACED BY ANOTHER SHOT OF COLD AIR LATE NEXT WEEK AS THE TROUGH DEEPENS. EXTENDED MODELS ONLY SHOWING LOOSE AGREEMENT IN THE OVERALL PATTERN AND DIFFER EVEN MORE ON DETAILS. THIS RESULTS IN BLO NORMAL CONFIDENCE IN THE DAY 4-7 FORECAST. IN THE WAKE OF THE SATURDAY CLIPPER LOW...EXPECT RESURGENCE IN LK EFFECT AS H85 TEMPS FALL OFF TOWARD -15C. SOUNDINGS INDICATE INVERSIONS UP TO 5KFT AND DEEP MOISTURE LEFT OVR FM THE DEPARTING LOW PRESSURE SYSTEM. PROGGED LIFT IS WITHIN MORE FAVORABLE SNOW GROWTH REGION AS WELL. 925-850MB WINDS ARE LIGHT WITH SPEEDS UP TO 15 KT SO THE SNOW SHOWERS WILL TEND TO HANG ALONG THE SHORE OR MOVE JUST INLAND. DUE TO THE FAVORABLE SNOW GROWTH LINED UP WITH THE LK EFFECT MOIST LAYER...MODERATE SNOW ACCUMS ARE POSSIBLE SUNDAY NIGHT INTO MONDAY. AT THIS POINT...MORE PERSISTENT SNOW SHOWERS LOOK TO SET UP OVR WESTERN AND NCNTRL AREAS AS LOW-LEVEL WINDS ARE FM N TO NNE. PINNING DOWN WHERE THE HEAVIER SNOW MAY OCCUR BECOMING MORE MUDDLED DUE TO INCREASING ICE COVER ON LK SUPERIOR. ONGOING LK EFFECT ON MONDAY WILL HAVE OPPORTUNITY TO INCREASE AS SHORTWAVE DROPS ALMOST NORTH TO SOUTH ACROSS UPR LAKES. SLIGHTLY BACKING WINDS MONDAY MORNING SHOULD SHIFT BACK MORE NRLY BY LATE DAY INTO THE EVENING. SHARPNESS OF WIND SHIFT MORE IN QUESTION. SINCE THIS WAVE IS JUST APPEARING IN GUIDANCE TODAY...DID NOT HIT IT TOO HARD YET. INCREASED POPS ALONG ALL OF LAKE SUPERIOR. AFTER THIS SFC TROUGH SHIFTS THROUGH...NW LK EFFECT WILL PERSIST THROUGH TUESDAY. WINDS BACK AHEAD OF COLD FRONT DROPPING INTO THE UPR LAKES LATE NEXT WEEK. KEPT POPS ON WED ONLY CONFINED TO KEWEENAW IN EXPECTED SW FLOW IN THE LOW-LEVELS. BEYOND WED NIGHT...CHOSE TO DISCOUNT 12Z GFS SOLUTION AS IT COMPLETELY BROKE CONTINUITY WITH PREVIOUS RUNS AND MAJORITY OF OTHER GUIDANCE BY KEEPING SW FLOW ALOFT OVR UPR LAKES AND DELAYING PUSH OF COLD AIR UNTIL NEXT FRIDAY. FORECAST IS MUCH MORE IN LINE WITH 00Z/12Z ECMWF AND LATEST HPC GUIDANCE. AFTER A PERIOD OF SNOW ALONG THE TROUGH WEDNESDAY NIGHT INTO THURSDAY...MORE LK EFFECT DEVELOPS IN N/NW FLOW AREAS INTO FRIDAY. COLD TEMPS RETURN WITH READINGS FALLING BACK BLO NORMAL. HOWEVER...TEMPS DO NOT LOOK TO FALL TO LEVELS SEEN THIS WEEK. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... AT KCMX...VFR CONDITIONS WILL DROP TO IFR CIGS/VSBY BEFORE DAYBREAK...THEN CONTINUE THROUGH THE MORNING. THIS LOWERING IN CIGS AND VSBYS IS IN RESPONSE TO A CLIPPER SYSTEM DROPPING THROUGH THE AREA. AS THE SNOW DIMINISHES IN THE AFTERNOON...CONDITIONS SHOULD IMPROVE TO MVFR. AT KSAW...DRY DOWNSLOPING SW FLOW WILL RESULT IN VFR CONDITIONS PREVAILING FOR A FEW MORE HOURS. A CLIPPER SYSTEM DROPPING INTO THE AREA SAT WILL BRING -SN AND IFR VIS/CIGS FOR SAT MORNING. AS THE SNOW TAPERS OFF...SOME IMPROVEMENT IS EXPECTED BY LATE SATURDAY AFTERNOON TO MVFR CONDITIONS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HEAVY FREEZING SPRAY SHOULD END OVER MOST OF LAKE SUPERIOR BY SUNRISE SAT. WINDS ARE EXPECTED TO STAY BLO GALE FORCE THRU THIS FCST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 AM TO 12 PM CST SATURDAY FOR MIZ010. WINTER WEATHER ADVISORY FROM 7 AM TO 7 PM EST SATURDAY FOR MIZ013-014. WINTER WEATHER ADVISORY FROM 6 AM TO 3 PM CST SATURDAY FOR MIZ011-012. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST SATURDAY FOR LSZ263- 264-266-267. && $$ SYNOPSIS/SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...JLB/AJ MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 221 AM CST SAT JAN 17 2009 .DISCUSSION... EARLY THIS MORNING A VERY POTENT SHORT WAVE WAS JUST NORTH OF THE MINNESOTA/CANADA BORDER WITH ACCUMULATING SNOWFALL MAINLY ACROSS THE ARROWHEAD OF MINNESOTA AND NORTHWESTERN WISCONSIN PRIOR TO 2 AM. VERY STRONG WINDS BEHIND THE SURFACE FRONT ACROSS THE DAKOTAS WAS PRODUCING WIND GUSTS IN EXCESS OF 40 TO 45 MPH...EVEN SOME OF THE WIND GUSTS AHEAD OF THIS FRONTAL BOUNDARY WAS CAUSING WIND GUSTS IN EXCESS OF 40 MPH IN WEST CENTRAL MINNESOTA WHERE TEMPERATURES HAVE RISEN 10 TO 15 DEGREES SINCE FRIDAY EVENING. PRIOR TO MIDNIGHT CANBY IN FAR WESTERN MINNESOTA WAS IN THE UPPER TEENS...JUST PRIOR TO 2 AM...TEMPERATURES ROSE TO 30. THIS IS NICE WARMING OVER THE BUFFALO RIDGE AND WILL ALLOW FOR EXTREME DIFFERENCES IN TEMPERATURES FROM THE MINNESOTA RIVER VALLEY TO THE TWIN CITIES AND WESTERN WISCONSIN THIS MORNING. EVEN BEHIND THIS FRONTAL BOUNDARY...TEMPERATURES WERE IN THE 20S ACROSS MONTANA AND SOUTH CENTRAL CANADA. DUE TO THESE DYMANIC CHANGES...SHORT TERM MODELS ARE HAVING A HARD TIME WITH EVEN THE WINDS ACROSS THE DAKOTAS...WHICH WILL LIKELY PLAY HAVOC WITH SATURDAY TEMPERATURES AND DEW POINTS AS EVEN THE SURFACE MOISTURE LEVELS HAVE INCREASED SIGNIFICANTLY. FORECAST CONCERNS FOR THIS FORECAST PERIOD WILL BE HAND EDITING WIND/TEMPERATURE/MOISTURE LEVELS NEAR THE SURFACE FOR THE FIRST 12 TO 18 HRS. AFTER TODAY...WILL FOLLOW THE WRF AS THIS MODEL HAD SOME INDICATIONS OF THE STRONGER WIND FIELD AND MOISTURE ADVECTION. SOUNDINGS ACROSS MPX CWA INCLUDING A CROSS SECTION FROM NEAR FSD TO NORTHWESTERN WISCONSIN...DOES SHOW AT LEAST SOME ELEVATED LIFT AND DEEPER MOISTURE FOR WEST CENTRAL WISCONSIN THIS MORNING WHICH WILL LEAD TO HIGHER PERCENTAGES OF SNOW CHANCES AND QPF...MAINLY BEFORE 18Z. AFTER 18Z SATURDAY...MOISTURE FIELDS ARE VERY SHALLOW AND THE MAIN FORCING ASSOCIATED WITH THE SHORT WAVE WILL LEAVE THE CWA. THEREFORE...ONLY FLURRIES OR FREEZING DRIZZLE IS EXPECTED. SOME INDICATIONS OF DEEPER MOISTURE AND SOME MINOR LIFT FOR LATE SATURDAY NIGHT AND SUNDAY MORNING MAY PRODUCE SOME MINOR SNOWFALL ACROSS EASTERN MINNESOTA AND WESTERN WISCONSIN...BUT OVERALL CHANCES REMAIN TOO LOW FOR ADDING LIGHT SNOW OR ACCUMULATIONS OF MORE THAN A DUSTING. LATER SHIFTS WILL NEED TO MONITOR THE AMOUNT OF MOISTURE AND ASSOCIATED LIFT WITH THE NEXT SYSTEM. MADE SOME ADJUSTMENTS IN TEMPERATURES AND DEW POINTS FOR SUNDAY THROUGH WEDNESDAY WITH OTHER WX PARAMETERS REASONABLE DUE TO THE OVERALL PATTERN SHIFT AND THICKNESS VALUES INCREASING. && .AVIATION.../06Z TAF ISSUANCE/ SFC LOW IN FAR ERN ND HEADING SEWD AND ENTIRE AREA IN WARM ADVECTION NOW. RUC SUGGESTS THIS WILL SLIDE NE OF STC/RNH SO HAVE TRENDED WINDS THROUGH THE SW TO NW. AS MENTIONED IN 326 PM DISCUSSION...FREEZING DRIZZLE HAS RECENTLY COMMENCED... ALL THE WAY FROM KINL AREA TO KMSP. WARM NOSE MOST EVIDENT ON PROFILES AS VIEWED WITH BUFKIT SUGGEST A FEW HOURS OF ZL ARE POSSIBLE AT STC/MSP/EAU/RNH...WITH EAU MOST PRONE TO IFR VSBYS FROM SNOW STARTING A LITTLE PRIOR TO 12Z. COLD ADVECTION TO FOLLOW AS LOW TREKS SEWD WITH MVFR WRAP AROUND...MOSTLY FROM CNTRL MN INTO WISC. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JLT/RAH mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1155 PM CST FRI JAN 16 2009 .UPDATE... UPDATED FOR AVIATION DISCUSSION BELOW. && .DISCUSSION... /ISSUED 326 PM CST FRI JAN 16 2009/ THE WARMING TREND HAS BEGUN WITH A FEW FLURRIES DEVELOPING FROM IA INTO CENTRAL MN. THE PRECIP TYPE STILL A LITTLE PROBLEMATIC TONIGHT. MAINLY LOW LEVEL MOISTURE THIS EVENING...AND FORECAST SOUNDINGS BOUNCE AROUND A BIT WITH SATURATION AROUND -10C. THERE ARE A FEW HOURS HERE AND THERE WHERE FREEZING MIGHT BE THE PRECIP TYPE..DURING THE EVENING AND SHORTLY AFTER MIDNIGHT. SIG SHORT WAVE SHOWING UP ON WATER VAPOR MODELS ESPECIALLY THE RUC AND NAM BRING IN WELL DEFINED OMEGA IN THE -15 C PLANE AND INCREASING THETA E ADVECTION. THIS WILL HELP TO BRING MORE COLUMN MOISTURE LATER TONIGHT AND SATURDAY MORNING. MICH OF THE FORCING COMES TOGETHER OVER EAST EASTERN MN AND WEST CENTRAL WI. WILL KEEP THE HIGHER POPS IN WI BUT INCREASE BACK INTO MN A BIT. UP TO 3 INCHES OF SNOW STILL POSSIBLE FOR PARTS OF WEST CENTRAL WI. WILL CONTINUE THE RISING TEMPE TREND OVERNIGHT AND MAY HAVE TO DO SOME LAST MINUTE ADJUSTMENTS. THE UPPER RIDGE IS STILL STRONG AFTER THE WAVE MOVES THROUGH SATURDAY MORNING...AND THE ASSOCIATED UPPER JET IN A NORTH TO SOUTH ORIENTATION TO OUR WEST WILL KEEP THE MORE SIGNIFICANT WARMING AT BAY UNTIL TUESDAY. A FEW MINOR RIPPLES MOVING SSE MAY GENERATE A FEW FLURRIES SATURDAY NIGHT INTO SUNDAY. THE WARMEST DAY STILL LOOKS LIKE WEDNESDAY AHEAD OF THE COLD FRONT. COULD EASILY SEE SOME MID 30S. GFS AND ECMWF THEN IN GENERAL AGREEMENT BRINGING ANOTHER ARCTIC INTRUSION BY FRIDAY..ALTHOUGH NOT AS INTENSE AS THE CURRENT AIRMASS. && .AVIATION.../06Z TAF ISSUANCE/ SFC LOW IN FAR ERN ND HEADING SEWD AND ENTIRE AREA IN WARM ADVECTION NOW. RUC SUGGESTS THIS WILL SLIDE NE OF STC/RNH SO HAVE TRENDED WINDS THROUGH THE SW TO NW. AS MENTIONED IN 326 PM DISCUSSION...FREEZING DRIZZLE HAS RECENTLY COMMENCED... ALL THE WAY FROM KINL AREA TO KMSP. WARM NOSE MOST EVIDENT ON PROFILES AS VIEWED WITH BUFKIT SUGGEST A FEW HOURS OF ZL ARE POSSIBLE AT STC/MSP/EAU/RNH...WITH EAU MOST PRONE TO IFR VSBYS FROM SNOW STARTING A LITTLE PRIOR TO 12Z. COLD ADVECTION TO FOLLOW AS LOW TREKS SEWD WITH MVFR WRAP AROUND...MOSTLY FROM CNTRL MN INTO WISC. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JPR/TDK mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1047 PM CST FRI JAN 16 2009 .AVIATION... 06Z TAFS... STILL THINK MVFR/IFR CONDITIONS ARE LIKELY TO STAY MOSTLY SE OF OUR TAF SITES TONIGHT. BUT LOW CLOUDS NOW SPREADING ACROSS TX ARE BECOMING MORE OF A CONCERN. LOW-LEVEL RH PROGS UNDERESTIMATED N-WARD EXTENT OF CLOUDS LAST NIGHT AND THIS MORNING. TONIGHT WE WILL LEAN MORE TOWARD THE HIGHER RUC SFC/BL RH AND THE LATEST SATELLITE TRENDS AND BRING STRATUS/FOG INTO KSPS AND POSSIBLY KLAW AREAS LATE TONIGHT AND SAT MORNING. VEERED FLOW JUST OFF SFC SHOULD KEEP IT SHALLOW... AND MIXING WILL HELP ERODE IT QUICKLY. OTHERWISE LITLE CHANGE TO TIMING OF WIND SHIFT MOVING SE ACROSS OK AND NORTH TX DURING THE DAY. && .PREV DISCUSSION... /ISSUED 948 PM CST FRI JAN 16 2009/ UPDATE... LOWER CLOUDS ARE CONFINED TO FAR SOUTHEAST OKLAHOMA AND EXPECT ANY REDEVELOPMENT WILL BE ACROSS SC/SE OK OVERNIGHT PER RUC RH FIELDS. APPEARS 00Z NAM IS OVERDONE WITH HUMIDITY AROUND 9H. WITH WINDS STAYING IN THE 10 TO 20 MPH RANGE OVERNIGHT...TEMPS WILL ONLY LOWER A FEW MORE DEGREES WITH INCREASING TEMPS ACROSS N TX SOUTHWEST OKLAHOMA AS HIGHER DEWPOINTS ADVECT NORTHWARD. 00Z NAM ALSO BRINGS A CANADIAN HIGH SOUTHWARD LATE SUNDAY INTO MONDAY. SOURCE REGION OF AIR IS MUCH WARMER THAN A WEEK AGO AS FRIGID AIR IS MAINLY OVER EASTERN THIRD OF CANADA. HOWEVER AIRMASS MAY BE COOL ENOUGH TO KEEP SOME AREAS IN THE MID TO UPPER 40S. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 28 56 31 55 / 0 0 0 0 HOBART OK 26 58 30 59 / 0 0 0 0 WICHITA FALLS TX 29 61 31 61 / 0 0 0 0 GAGE OK 24 58 25 60 / 0 0 0 0 PONCA CITY OK 24 52 24 51 / 0 0 0 0 DURANT OK 27 58 35 57 / 0 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 06/24/24 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 845 AM MST SAT JAN 17 2009 .UPDATE... 837 AM MST SAT JAN 17 2009 MAIN FORECAST CONCERN FOR TODAY WILL CONTINUE TO BE WIND SPEEDS AND THE NEED...IF ANY FOR A WIND ADVISORY. WINDS ALREADY INCREASING TO IN EXCESS OF 20 KTS WITH RELATIVELY LITTLE HEATING AND CONCERN IS INCREASING FOR THE NEED OF AN ADVISORY. MODIFYING FCST SOUNDINGS WITH EXPECTED AFTERNOON TEMPS WOULD SUPPORT ADVISORY TO NEAR ADVISORY CONDITIONS ACROSS MUCH OF THE CWA. LATEST RUC BUFKIT SOUNDINGS KEEP THINGS BELOW CRITERIA...BUT ALSO APPEAR TO KEEP TEMPS LESS THAN 50 DEGREES ALL DAY WHICH APPEARS UNLIKELY. HAVE UPPED WINDS ACROSS THE AREA AND SPED UP THEIR INCREASE...BUT SINCE THIS LOOKS LIKE A LOW END/MARGINAL ADVISORY PLAN ON WATCHING OBSERVATIONS FOR A WHILE BEFORE MAKING ANY FINAL CALL. CWA MAY ALSO APPROACH RED FLAG CRITERIA AS DEEPER MIXING DROPS TDS INTO THE TEENS. WITH RECENT SNOW MELT UNSURE HOW MUCH EVAPORATION WILL OCCUR AND HOW MUCH THAT WILL OFFSET MIXING. FOR NOW IT LOOKS LIKE CONDITIONS WILL APPROACH....BUT NOT EXCEED CRITERIA. JRM && .DISCUSSION... 200 AM MST SAT JAN 17 2009 TEMPERATURES AND WIND SPEEDS ARE THE FORECAST PROBLEMS THROUGH THE SHORT TERM PERIOD. FIRE WEATHER MAY ALSO BECOME A CONCERN WITH MUCH ABOVE NORMAL TEMPERATURES AND WINDY CONDITIONS PERSISTING INTO EARLY NEXT WEEK. SHORTWAVE TROUGH MOVING THROUGH THE FORECAST AREA EARLY THIS MORNING...ACCOMPANIED BY MID LEVEL CLOUDS AND SUBTLE WIND SHIFT TO THE NORTHWEST AT THE SURFACE. THE FRONT WILL HAVE MINIMAL IMPACT ON TEMPERATURES. TIGHT PRESSURE GRADIENT EXISTS IN POST FRONTAL ENVIRONMENT AND THERE IS A POCKET OF 800MB WINDS OF UP TO 60KTS OVER THE WESTERN CWA EARLY THIS MORNING...BUT LOWER LEVELS WILL BE DECOUPLED. BUFKIT SHOWS MIXING WILL NOT REALLY GET UNDERWAY UNTIL AFTER 18Z AND THE MIXED LAYER HEIGHTS FORECAST TO BE LESS THAN 800MB AT PEAK HEATING THIS AFTERNOON...BY THAT TIME WINDS WILL BE DIMINISHING. ALL THINGS CONSIDERED...MAY SEE A FEW GUSTS APPROACHING 40KTS...BUT SHOULD BE BRIEF AND LOCALIZED SO WILL NOT ISSUE ANY WIND HIGHLIGHTS. AS FOR FIRE WEATHER...APPEARS SLIGHTLY COOLER AIR BEHIND THE FRONT WILL BE JUST ENOUGH TO KEEP RH VALUES ABOVE THE CRITICAL 15% THRESHOLD...ALTHOUGH THEY DO DIP TO AROUND 20%. ANOTHER CLOSE CALL FOR RED FLAG...BUT BELIEVE WILL FALL SHORT. HOWEVER...WILL MENTION THOSE CONDITIONS IN FIRE WEATHER FORECAST PRODUCT. IN THE SUNDAY THROUGH TUESDAY PERIOD...UPPER RIDGE OVER THE GREAT BASIN WILL GRADUALLY MIGRATE EASTWARD TOWARDS THE ROCKIES AS IT AMPLIFIES. 500MB HEIGHTS WILL RISE OVER THE CENTRAL HIGH PLAINS. PROXIMITY OF THE RIDGE WILL PROTECT THE AREA FROM ANY ARCTIC COLD FRONTS. 850MB TEMPERATURES RISE EACH DAY...PEAKING AROUND TUESDAY IN THE LOWER 20S CELSIUS...WHICH IS FAIRLY IMPRESSIVE FOR JANUARY. A FEW RECORD HIGH TEMPERATURES WILL PROBABLY BE SET IN THIS PERIOD. SINCE THE AREA WILL BE ON THE EASTERN PERIPHERY OF THE RIDGE...THERE WILL BE A TIGHT HEIGHT GRADIENT OVER OR VERY CLOSE...WHICH MEANS THE POTENTIAL TO MIX DOWN GUSTY WINDS WITH PEAK HEATING. IN ADDITION...THE AREA HAS BEEN VERY DRY FOR MOST OF THE PAST MONTH...EXEMPLIFIED BY A SMALL GRASS FIRE REPORTED IN NORTON COUNTY ON FRIDAY. ALL OF THIS LEADS TO FIRE WEATHER CONCERNS...BEGINNING ON SUNDAY AND PROBABLY CONTINUING AT LEAST THROUGH TUESDAY. FAILED TO COORDINATE A FIRE WEATHER WATCH FOR SUNDAY...WHEN CONDITIONS WILL ADMITTEDLY BY MARGINAL...SO WILL PASS CONCERNS TO THE NEXT SHIFT AND MENTION IN OTHER PRODUCTS. 24 && .AVIATION... 414 AM MST SAT JAN 17 2009 FOR THE 12Z TAFS...VFR CONDITIONS ARE EXPECTED THROUGH THE ENTIRE PERIOD. MAIN FEATURE OF INTEREST WILL BE THE GUSTY NORTHWEST WINDS DURING THE DAYTIME HOURS. WINDS WILL STOP GUSTING AND BE MORE STEADY WHEN SUNSET APPROACHES. BULLER && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1055 AM EST SAT JAN 17 2009 .SYNOPSIS... WATER VAPOR IMAGERY AND RUC SHOW A LONGWAVE TROUGH OVER EASTERN NORTH AMERICA AND A RIDGE OVER THE PACIFIC NORTHWEST. A PRONOUNCED SHORTWAVE TROUGH SLIDING DOWN THE LEE OF THE RIDGE IS OVER WESTERN U.P. WEAKER SHORTWAVES ARE OVER WESTERN ONTARIO AND NORTHEAST SASKTACHEWAN. SURFACE ANALYSIS DEPICTS A LOW OVER NORTHERN WISCONSIN WITH A WARM FRONT DRAPED SOUTHWEST INTO THE SOUTH CENTRAL PLAINS. AN INVERTED TROUGH ALSO STRETCHES NORTH THROUGH WESTERN ONTARIO. A WEAK SURFACE TROUGH IS OVER EAST CENTRAL ONTARIO AND SOUTHERN QUEBEC. A DOME OF HIGH PRESSURE BLANKETS THE ROCKIES PUSHING THIS SYSTEM EAST...WHILE A WEAKER RIDGE EXTENDING ALONG THE SOUTHERN AND MID ATLANTIC STATES IMPEDES ITS MOVEMENT. ISENTROPIC ASCENT AND Q-VECTOR CONVERGENCE AHEAD OF THE LOW CONTINUES TO GENERATE SNOW OVER THE FORECAST AREA. A DRY SLOT ACCOMPANYING THE LOW IS OVER NORTHERN WISCONSIN. && .SHORT TERM...THIS AFTERNOON. THE MODELS ARE IN A FAIRLY GOOD AGREEMENT THROUGH MONDAY. GFS STARTS TO BE THE OUTLIER AFTER THAT. THUS I FAVOR USING THE CONSENSUS. THE SHORTWAVE OVER THE WESTERN U.P. WILL SHIFT INTO THE CENTRAL U.P. AND EASTERN WISCONSIN BY MID AFTERNOON. MEANHILE...THE ACCOMPANYING SURFACE LOW WILL MOVE INTO NORTHERN LAKE MICHIGAN DRAWING THE SURFACE TROUGH INTO THE CENTRAL U.P. ISENTROPIC ASCENT AND SHORTWAVE ENERGY WILL CONTINUE TO GENERATE SNOWS OVER THE AREA. THE DRY SLOT SHOULD START TO MOVE INTO PORTIONS OF WESTERN U.P. REDUCE SNOWFALL THIS AFTERNOON. THE CURRENT GRIDS SEEMS TO REFLECT THIS VERY WELL. AS NOTED EARLIER...DEEP LAYER WITHIN DENDRITIC GROWTH ZONE AS NOTED ON MODEL SOUNDINGS WILL ALSO YIELD HIGH SNOW/WATER RATIOS PROBABLY FROM 20-25/1 FOR IRON THROUGH MENOMINEE COUNTIES INTO MID AFTERNOON. LAKE ENHANCEMENT OFF LAKE MICHIGAN IS ALSO A GOOD POSSIBILITY AS MESOSCALE MODELS INDICATE LOW-LVL FLOW SHIFTING FROM SOUTHWEST TO MORE SOUTHERLY DIRECTION BY LATE MORNING. && .LONG TERM...TONIGHT AND LATER. IN THE WAKE OF THE TODAY`S CLIPPER SYSTEM...EXPECT MORE LAKE EFFECT SNOW IN A CYCLONIC NRLY FLOW LATE TODAY THROUGH SUNDAY AS H85 TEMPS FALL TO -16/-17C. SOUNDINGS INDICATE INVERSIONS UP TO 5KFT AND LINGERING DEEP MOISTURE LEFT OVR FM THE DEPARTING LOW PRESSURE SYSTEM. ALSO PROGGED OMEGA/LIFT IS WITHIN MORE FAVORABLE SNOW GROWTH REGION AS NOTED ON MODEL FCST SNDGS. GIVEN FAVORABLE SNOW GROWTH AND GOOD LLVL CONV AS NOTED ON WRF-ARW...ESPECIALLY OVER GOGEBIC-ONTONAGON WOULD EXPECT SOME LOCATIONS TO REACH ADVISORY CRITERIA SNOW AMTS FOR ANY 12 HR PD. THUS...HAVE DECIDED TO ISSUE A LES ADVISORY FROM LATE TODAY THROUGH SUNDAY. FLOW SHOULD BEGIN TO WEAKEN SUNDAY NIGHT AS SFC RIDGE ADVANCES FROM THE WEST IN RESPONSE TO ANOTHER CLIPPER SYSTEM DIVING SOUTH FROM CANADA. LOOK FOR WINDS TO GRADUALLY BACK NW AS LAKE EFFECT SNOW TAPERS OFF ACROSS THE NRN TIER. DPVA/Q-VECT CONV SPREADING ACROSS THE AREA AHEAD OF THE NEXT CLIPPER SYSTEM SHOULD BRING ANOTHER SHOT OF LIGHT SNOW ON MONDAY. WILL KEEP CHC POPS ACROSS THE FCST AREA WITH HIGHER CHC POPS OVER THE NRN TIER CLOSER TO THE TRACK OF THE SHORTWAVE AND WITH A POSSIBILITY OF MORE LES BEHIND THE SYSTEM. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... LIGHT SNOW ENCOMPASSES MUCH OF UPPER MI EARLY THIS MORNING TO THE EAST OF A CLIPPER DROPPING THROUGH MN. EXPECT THIS LIGHT SNOW TO REMAIN FAIRLY STEADY THROUGH MUCH OF THE DAY AS THE LOW MOVES SE TO LAKE MI THIS EVENING. THEREFORE...HAVE KEPT GENERAL IFR VSBYS AND MVFR/IFR CIGS GOING. THERE IS POTENTIAL FOR SOME HEAVIER SNOW MOVING INTO KSAW PER LATEST RADAR LOOP AND LOCAL MODEL RUNS...SO TO COVER THE POSSIBILITY HAVE INCLUDED A TEMPO GROUP FOR LIFR CONDITIONS. THE SNOW SHOULD TAPER OFF LATE THIS AFTN...SO BROUGHT VSBYS/CIGS AT BOTH TAF SITES TO MVFR...AND EVEN VFR AT CMX. TONIGHT...A SFC TROUGH EXTENDING NORTH FROM THE LOW WILL MOVE SLOWLY TO THE SW WITH TIME. LAKE EFFECT SNOW SHOULD CONGEAL ALONG THE TROUGH...ENTERING CMX SOMETIME AFTER 06Z AND THEN ENDING VERY LATE AS WINDS TURN NE. AT SAW...LAKE EFFECT SNOW LOOKS LIKELY THROUGH THE ENTIRE NIGHT... EITHER ASSOCIATED WITH THE TROUGH OR THE NE WINDS BEHIND IT. THEREFORE...A CONTINUATION OF MVFR VSBYS/CIGS ARE PLANNED FOR SAW. IFR CONDITIONS MAY OCCUR AS WELL...BUT CONFIDENCE IS TOO LOW TO INCLUDE AT THE MOMENT. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HEAVY FREEZING SPRAY WILL DIMINISH ON WESTERN LAKE SUPERIOR BY SUNRISE DUE TO DIMINISHING WINDS. STRONGER SOUTHERLY FLOW ON EASTERN LAKE SUPERIOR AHEAD OF A CLIPPER...COMBINED WITH A COLD AIRMASS IN PLACE...WILL RESULT IN KEEPING HEAVY FREEZING SPRAY GOING THROUGH TODAY. THE HEAVY FREEZING SPRAY ON EASTERN SUPERIOR SHOULD END THIS EVENING AS WINDS DIMINISH THERE. WINDS ARE EXPECTED TO STAY BLO GALE FORCE THRU THIS FCST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ010. WINTER WEATHER ADVISORY UNTIL TO 7 PM EST THIS EVENING FOR MIZ013-014. WINTER WEATHER ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR MIZ011-012. LAKE EFFECT SNOW ADVISORY FROM 4 PM THIS AFTERNOON UNTIL 7 PM SUNDAY FOR MIZ002-009. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ266-267. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/SHORT TERM...DLG LONG TERM...VOSS AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 643 AM EST SAT JAN 17 2009 UPDATED AVIATION DISCUSSION FOR 12Z TAF ISSUANCE .SYNOPSIS... 10Z WATER VAPOR IMAGERY AND RUC ANALYSIS SHOWS WELL-DEFINED SHORTWAVE DIGGING SOUTH INTO NRN MN. DPVA AND STRONG 280-285K ISENTROPIC ASCENT AHEAD OF THIS SHORTWAVE HAS SPREAD LIGHT TO MODERATE SNOW INTO THE FCST AREA THIS MORNING AS NOTED ON REGIONAL RADAR LOOP AND SFC OBS. && .DISCUSSION... AS SHORTWAVE FROM NORTHERN PLAINS DIGS SOUTHEAST ACROSS THE FORECAST AREA THIS MORNING DEEP Q-VECT CONV AND 280-285K ISENTROPIC ASCENT WILL SPREAD E ACROSS UPR MI. PERIOD OF STRONG ISENTROPIC ASCENT IS FAIRLY BRIEF (6-9 HRS) WITH MIXING RATIOS OF 2G/KG AVBL. LOOK FOR TOTAL ACCUMULATIONS GENERALLY FROM 2-3 INCHES ACROSS THE WEST AND NCNTRL COUNTIES. EXPECT HIGHER AMOUNTS OF 3-5 INCHES ALONG THE WI BDR COUNTIES CLOSER TO BEST LIFT AND NORTH OF THE TRACK OF DEEPENING SFC LOW. DEEP LAYER WITHIN DENDRITIC GROWTH ZONE AS NOTED ON MODEL SNDGS WILL ALSO YIELD HIGH SNOW/WATER RATIOS PROBABLY FROM 20-25/1. THUS...SNOW ADVISORIES STILL LOOK GOOD FOR IRON THROUGH MNM COUNTIES THIS MORNING INTO MID AFTERNOON. LAKE ENHANCEMENT OFF LAKE MI IS ALSO A GOOD POSSIBILITY AS MESOSCALE MODELS INDICATE LOW-LVL FLOW SHIFTING FROM SW TO MORE SRLY DIRECTION BY LATE MORNING. HOWEVER...SINCE MODELS INDICATE THAT THE BEST CONVERGENCE NEVER STAYS OVER ONE AREA FOR MORE THAN A COUPLE OF HRS...HAVE DECIDED AGAINST UPGRADING ADVISORY TO WARNING FOR DELTA AND SRN SCHOOLCRAFT. WILL MAINTAIN HIGH END ADVISORY AMTS OF 3-7 INCHES...HIGHEST OVER THE GARDEN PENINSULA INTO SRN SCHOOLCRAFT COUNTY. IN THE WAKE OF THE TODAY`S CLIPPER SYSTEM...EXPECT MORE LAKE EFFECT SNOW IN A CYCLONIC NRLY FLOW LATE TODAY THROUGH SUNDAY AS H85 TEMPS FALL TO -16/-17C. SOUNDINGS INDICATE INVERSIONS UP TO 5KFT AND LINGERING DEEP MOISTURE LEFT OVR FM THE DEPARTING LOW PRESSURE SYSTEM. ALSO PROGGED OMEGA/LIFT IS WITHIN MORE FAVORABLE SNOW GROWTH REGION AS NOTED ON MODEL FCST SNDGS. GIVEN FAVORABLE SNOW GROWTH AND GOOD LLVL CONV AS NOTED ON WRF-ARW...ESPECIALLY OVER GOGEBIC-ONTONAGON WOULD EXPECT SOME LOCATIONS TO REACH ADVISORY CRITERIA SNOW AMTS FOR ANY 12 HR PD. THUS...HAVE DECIDED TO ISSUE A LES ADVISORY FROM LATE TODAY THROUGH SUNDAY. FLOW SHOULD BEGIN TO WEAKEN SUNDAY NIGHT AS SFC RIDGE ADVANCES FROM THE WEST IN RESPONSE TO ANOTHER CLIPPER SYSTEM DIVING SOUTH FROM CANADA. LOOK FOR WINDS TO GRADUALLY BACK NW AS LAKE EFFECT SNOW TAPERS OFF ACROSS THE NRN TIER. DPVA/Q-VECT CONV SPREADING ACROSS THE AREA AHEAD OF THE NEXT CLIPPER SYSTEM SHOULD BRING ANOTHER SHOT OF LIGHT SNOW ON MONDAY. WILL KEEP CHC POPS ACROSS THE FCST AREA WITH HIGHER CHC POPS OVER THE NRN TIER CLOSER TO THE TRACK OF THE SHORTWAVE AND WITH A POSSIBILITY OF MORE LES BEHIND THE SYSTEM. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... LIGHT SNOW ENCOMPASSES MUCH OF UPPER MI EARLY THIS MORNING TO THE EAST OF A CLIPPER DROPPING THROUGH MN. EXPECT THIS LIGHT SNOW TO REMAIN FAIRLY STEADY THROUGH MUCH OF THE DAY AS THE LOW MOVES SE TO LAKE MI THIS EVENING. THEREFORE...HAVE KEPT GENERAL IFR VSBYS AND MVFR/IFR CIGS GOING. THERE IS POTENTIAL FOR SOME HEAVIER SNOW MOVING INTO KSAW PER LATEST RADAR LOOP AND LOCAL MODEL RUNS...SO TO COVER THE POSSIBILITY HAVE INCLUDED A TEMPO GROUP FOR LIFR CONDITIONS. THE SNOW SHOULD TAPER OFF LATE THIS AFTN...SO BROUGHT VSBYS/CIGS AT BOTH TAF SITES TO MVFR...AND EVEN VFR AT CMX. TONIGHT...A SFC TROUGH EXTENDING NORTH FROM THE LOW WILL MOVE SLOWLY TO THE SW WITH TIME. LAKE EFFECT SNOW SHOULD CONGEAL ALONG THE TROUGH...ENTERING CMX SOMETIME AFTER 06Z AND THEN ENDING VERY LATE AS WINDS TURN NE. AT SAW...LAKE EFFECT SNOW LOOKS LIKELY THROUGH THE ENTIRE NIGHT... EITHER ASSOCIATED WITH THE TROUGH OR THE NE WINDS BEHIND IT. THEREFORE...A CONTINUATION OF MVFR VSBYS/CIGS ARE PLANNED FOR SAW. IFR CONDITIONS MAY OCCUR AS WELL...BUT CONFIDENCE IS TOO LOW TO INCLUDE AT THE MOMENT. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HEAVY FREEZING SPRAY WILL DIMINISH ON WESTERN LAKE SUPERIOR BY SUNRISE DUE TO DIMINISHING WINDS. STRONGER SOUTHERLY FLOW ON EASTERN LAKE SUPERIOR AHEAD OF A CLIPPER...COMBINED WITH A COLD AIRMASS IN PLACE...WILL RESULT IN KEEPING HEAVY FREEZING SPRAY GOING THROUGH TODAY. THE HEAVY FREEZING SPRAY ON EASTERN SUPERIOR SHOULD END THIS EVENING AS WINDS DIMINISH THERE. WINDS ARE EXPECTED TO STAY BLO GALE FORCE THRU THIS FCST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ010. WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST THIS EVENING FOR MIZ013-014. WINTER WEATHER ADVISORY FROM 6 AM THIS MORNING TO 3 PM CST THIS AFTERNOON FOR MIZ011-012. LAKE EFFECT SNOW ADVISORY FROM 4 PM THIS AFTERNOON UNTIL 7 PM SUNDAY FOR MIZ002-009. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ266-267. HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST THIS MORNING FOR LSZ263-264. LAKE MICHIGAN...NONE. && $$ DISCUSSION...VOSS AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 614 AM EST SAT JAN 17 2009 UPDATED FOR ISSUE AN LES ADVISORY FOR GOGEBIC AND ONTONAGON COUNTIES LATE TODAY INTO SUNDAY .SYNOPSIS... 10Z WATER VAPOR IMAGERY AND RUC ANALYSIS SHOWS WELL-DEFINED SHORTWAVE DIGGING SOUTH INTO NRN MN. DPVA AND STRONG 280-285K ISENTROPIC ASCENT AHEAD OF THIS SHORTWAVE HAS SPREAD LIGHT TO MODERATE SNOW INTO THE FCST AREA THIS MORNING AS NOTED ON REGIONAL RADAR LOOP AND SFC OBS. && .DISCUSSION... AS SHORTWAVE FROM NORTHERN PLAINS DIGS SOUTHEAST ACROSS THE FORECAST AREA THIS MORNING DEEP Q-VECT CONV AND 280-285K ISENTROPIC ASCENT WILL SPREAD E ACROSS UPR MI. PERIOD OF STRONG ISENTROPIC ASCENT IS FAIRLY BRIEF (6-9 HRS) WITH MIXING RATIOS OF 2G/KG AVBL. LOOK FOR TOTAL ACCUMULATIONS GENERALLY FROM 2-3 INCHES ACROSS THE WEST AND NCNTRL COUNTIES. EXPECT HIGHER AMOUNTS OF 3-5 INCHES ALONG THE WI BDR COUNTIES CLOSER TO BEST LIFT AND NORTH OF THE TRACK OF DEEPENING SFC LOW. DEEP LAYER WITHIN DENDRITIC GROWTH ZONE AS NOTED ON MODEL SNDGS WILL ALSO YIELD HIGH SNOW/WATER RATIOS PROBABLY FROM 20-25/1. THUS...SNOW ADVISORIES STILL LOOK GOOD FOR IRON THROUGH MNM COUNTIES THIS MORNING INTO MID AFTERNOON. LAKE ENHANCEMENT OFF LAKE MI IS ALSO A GOOD POSSIBILITY AS MESOSCALE MODELS INDICATE LOW-LVL FLOW SHIFTING FROM SW TO MORE SRLY DIRECTION BY LATE MORNING. HOWEVER...SINCE MODELS INDICATE THAT THE BEST CONVERGENCE NEVER STAYS OVER ONE AREA FOR MORE THAN A COUPLE OF HRS...HAVE DECIDED AGAINST UPGRADING ADVISORY TO WARNING FOR DELTA AND SRN SCHOOLCRAFT. WILL MAINTAIN HIGH END ADVISORY AMTS OF 3-7 INCHES...HIGHEST OVER THE GARDEN PENINSULA INTO SRN SCHOOLCRAFT COUNTY. IN THE WAKE OF THE TODAY`S CLIPPER SYSTEM...EXPECT MORE LAKE EFFECT SNOW IN A CYCLONIC NRLY FLOW LATE TODAY THROUGH SUNDAY AS H85 TEMPS FALL TO -16/-17C. SOUNDINGS INDICATE INVERSIONS UP TO 5KFT AND LINGERING DEEP MOISTURE LEFT OVR FM THE DEPARTING LOW PRESSURE SYSTEM. ALSO PROGGED OMEGA/LIFT IS WITHIN MORE FAVORABLE SNOW GROWTH REGION AS NOTED ON MODEL FCST SNDGS. GIVEN FAVORABLE SNOW GROWTH AND GOOD LLVL CONV AS NOTED ON WRF-ARW...ESPECIALLY OVER GOGEBIC-ONTONAGON WOULD EXPECT SOME LOCATIONS TO REACH ADVISORY CRITERIA SNOW AMTS FOR ANY 12 HR PD. THUS...HAVE DECIDED TO ISSUE A LES ADVISORY FROM LATE TODAY THROUGH SUNDAY. FLOW SHOULD BEGIN TO WEAKEN SUNDAY NIGHT AS SFC RIDGE ADVANCES FROM THE WEST IN RESPONSE TO ANOTHER CLIPPER SYSTEM DIVING SOUTH FROM CANADA. LOOK FOR WINDS TO GRADUALLY BACK NW AS LAKE EFFECT SNOW TAPERS OFF ACROSS THE NRN TIER. DPVA/Q-VECT CONV SPREADING ACROSS THE AREA AHEAD OF THE NEXT CLIPPER SYSTEM SHOULD BRING ANOTHER SHOT OF LIGHT SNOW ON MONDAY. WILL KEEP CHC POPS ACROSS THE FCST AREA WITH HIGHER CHC POPS OVER THE NRN TIER CLOSER TO THE TRACK OF THE SHORTWAVE AND WITH A POSSIBILITY OF MORE LES BEHIND THE SYSTEM. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... AT KCMX...VFR CONDITIONS WILL DROP TO IFR CIGS/VSBY BEFORE DAYBREAK...THEN CONTINUE THROUGH THE MORNING. THIS LOWERING IN CIGS AND VSBYS IS IN RESPONSE TO A CLIPPER SYSTEM DROPPING THROUGH THE AREA. AS THE SNOW DIMINISHES IN THE AFTERNOON...CONDITIONS SHOULD IMPROVE TO MVFR. AT KSAW...DRY DOWNSLOPING SW FLOW WILL RESULT IN VFR CONDITIONS PREVAILING FOR A FEW MORE HOURS. A CLIPPER SYSTEM DROPPING INTO THE AREA SAT WILL BRING -SN AND IFR VIS/CIGS FOR SAT MORNING. AS THE SNOW TAPERS OFF...SOME IMPROVEMENT IS EXPECTED BY LATE SATURDAY AFTERNOON TO MVFR CONDITIONS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HEAVY FREEZING SPRAY WILL DIMINISH ON WESTERN LAKE SUPERIOR BY SUNRISE DUE TO DIMINISHING WINDS. STRONGER SOUTHERLY FLOW ON EASTERN LAKE SUPERIOR AHEAD OF A CLIPPER...COMBINED WITH A COLD AIRMASS IN PLACE...WILL RESULT IN KEEPING HEAVY FREEZING SPRAY GOING THROUGH TODAY. THE HEAVY FREEZING SPRAY ON EASTERN SUPERIOR SHOULD END THIS EVENING AS WINDS DIMINISH THERE. WINDS ARE EXPECTED TO STAY BLO GALE FORCE THRU THIS FCST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ010. WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST THIS EVENING FOR MIZ013-014. WINTER WEATHER ADVISORY FROM 6 AM THIS MORNING TO 3 PM CST THIS AFTERNOON FOR MIZ011-012. LAKE EFFECT SNOW ADVISORY FROM 4 PM THIS AFTERNOON UNTIL 7 PM SUNDAY FOR MIZ002-009. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ266-267. HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST THIS MORNING FOR LSZ263-264. LAKE MICHIGAN...NONE. && $$ DISCUSSION...VOSS AVIATION...JLB/AJ MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 545 AM EST SAT JAN 17 2009 .SYNOPSIS... 10Z WATER VAPOR IMAGERY AND RUC ANALYSIS SHOWS WELL-DEFINED SHORTWAVE DIGGING SOUTH INTO NRN MN. DPVA AND STRONG 280-285K ISENTROPIC ASCENT AHEAD OF THIS SHORTWAVE HAS SPREAD LIGHT TO MODERATE SNOW INTO THE FCST AREA THIS MORNING AS NOTED ON REGIONAL RADAR LOOP AND SFC OBS. && .DISCUSSION... AS SHORTWAVE FROM NORTHERN PLAINS DIGS SOUTHEAST ACROSS THE FORECAST AREA THIS MORNING DEEP Q-VECT CONV AND 280-285K ISENTROPIC ASCENT WILL SPREAD E ACROSS UPR MI. PERIOD OF STRONG ISENTROPIC ASCENT IS FAIRLY BRIEF (6-9 HRS) WITH MIXING RATIOS OF 2G/KG AVBL. LOOK FOR TOTAL ACCUMULATIONS GENERALLY FROM 2-3 INCHES ACROSS THE WEST AND NCNTRL COUNTIES. EXPECT HIGHER AMOUNTS OF 3-5 INCHES ALONG THE WI BDR COUNTIES CLOSER TO BEST LIFT AND NORTH OF THE TRACK OF DEEPENING SFC LOW. DEEP LAYER WITHIN DENDRITIC GROWTH ZONE AS NOTED ON MODEL SNDGS WILL ALSO YIELD HIGH SNOW/WATER RATIOS PROBABLY FROM 20-25/1. THUS...SNOW ADVISORIES STILL LOOK GOOD FOR IRON THROUGH MNM COUNTIES THIS MORNING INTO MID AFTERNOON. LAKE ENHANCEMENT OFF LAKE MI IS ALSO A GOOD POSSIBILITY AS MESOSCALE MODELS INDICATE LOW-LVL FLOW SHIFTING FROM SW TO MORE SRLY DIRECTION BY LATE MORNING. HOWEVER...SINCE MODELS INDICATE THAT THE BEST CONVERGENCE NEVER STAYS OVER ONE AREA FOR MORE THAN A COUPLE OF HRS...HAVE DECIDED AGAINST UPGRADING ADVISORY TO WARNING FOR DELTA AND SRN SCHOOLCRAFT. WILL MAINTAIN HIGH END ADVISORY AMTS OF 3-7 INCHES...HIGHEST OVER THE GARDEN PENINSULA INTO SRN SCHOOLCRAFT COUNTY. IN THE WAKE OF THE TODAY`S CLIPPER SYSTEM...EXPECT MORE LAKE EFFECT SNOW IN A CYCLONIC NRLY FLOW LATE TODAY THROUGH SUNDAY AS H85 TEMPS FALL TO -16/-17C. SOUNDINGS INDICATE INVERSIONS UP TO 5KFT AND LINGERING DEEP MOISTURE LEFT OVR FM THE DEPARTING LOW PRESSURE SYSTEM. ALSO PROGGED OMEGA/LIFT IS WITHIN MORE FAVORABLE SNOW GROWTH REGION AS NOTED ON MODEL FCST SNDGS. GIVEN FAVORABLE SNOW GROWTH AND GOOD LLVL CONV...ESPECIALLY OVER GOGEBIC-ONTONAGON AND MQT COUNTY WOULD NOT BE SHOCKED TO SEE LOCAL SNOW ACCUMS REACH ADVISORY CRITERIA FOR ANY 12 HR PD. GIVEN THAT THERE IS STILL SOME MODEL DISCREPANCY AS TO EXACTLY WHERE THE MORE DOMINANT BANDS WILL FORM... HAVE DECIDED TO KEEP SNOW AMTS JUST BLO ADVISORY CRITERIA FOR NOW...BUT THIS WILL NEED TO BE MONITORED ON THE DAY SHIFT FOR A POSSIBLE HEADLINE LATE TODAY INTO SUNDAY. FLOW SHOULD BEGIN TO WEAKEN SUNDAY NIGHT AS SFC RIDGE ADVANCES FROM THE WEST IN RESPONSE TO ANOTHER CLIPPER SYSTEM DIVING SOUTH FROM CANADA. LOOK FOR WINDS TO GRADUALLY BACK NW AS LAKE EFFECT SNOW TAPERS OFF ACROSS THE NRN TIER. DPVA/Q-VECT CONV SPREADING ACROSS THE AREA AHEAD OF THE NEXT CLIPPER SYSTEM SHOULD BRING ANOTHER SHOT OF LIGHT SNOW ON MONDAY. WILL KEEP CHC POPS ACROSS THE FCST AREA WITH HIGHER CHC POPS OVER THE NRN TIER CLOSER TO THE TRACK OF THE SHORTWAVE AND WITH A POSSIBILITY OF MORE LES BEHIND THE SYSTEM. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... AT KCMX...VFR CONDITIONS WILL DROP TO IFR CIGS/VSBY BEFORE DAYBREAK...THEN CONTINUE THROUGH THE MORNING. THIS LOWERING IN CIGS AND VSBYS IS IN RESPONSE TO A CLIPPER SYSTEM DROPPING THROUGH THE AREA. AS THE SNOW DIMINISHES IN THE AFTERNOON...CONDITIONS SHOULD IMPROVE TO MVFR. AT KSAW...DRY DOWNSLOPING SW FLOW WILL RESULT IN VFR CONDITIONS PREVAILING FOR A FEW MORE HOURS. A CLIPPER SYSTEM DROPPING INTO THE AREA SAT WILL BRING -SN AND IFR VIS/CIGS FOR SAT MORNING. AS THE SNOW TAPERS OFF...SOME IMPROVEMENT IS EXPECTED BY LATE SATURDAY AFTERNOON TO MVFR CONDITIONS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HEAVY FREEZING SPRAY WILL DIMINISH ON WESTERN LAKE SUPERIOR BY SUNRISE DUE TO DIMINISHING WINDS. STRONGER SOUTHERLY FLOW ON EASTERN LAKE SUPERIOR AHEAD OF A CLIPPER...COMBINED WITH A COLD AIRMASS IN PLACE...WILL RESULT IN KEEPING HEAVY FREEZING SPRAY GOING THROUGH TODAY. THE HEAVY FREEZING SPRAY ON EASTERN SUPERIOR SHOULD END THIS EVENING AS WINDS DIMINISH THERE. WINDS ARE EXPECTED TO STAY BLO GALE FORCE THRU THIS FCST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY UNTIL NOON CST TODAY FOR MIZ010. WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST THIS EVENING FOR MIZ013-014. WINTER WEATHER ADVISORY FROM 6 AM THIS MORNING TO 3 PM CST THIS AFTERNOON FOR MIZ011-012. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ266-267. HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST THIS MORNING FOR LSZ263-264. LAKE MICHIGAN...NONE. && $$ DISCUSSION...VOSS AVIATION...JLB/AJ MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 945 AM CST SAT JAN 17 2009 .DISCUSSION... FORECAST CHALLENGE FOR UPDATE CONCERNS TEMPERATURES AND SNOW CHANCES. HAVE ALLOWED CURRENT ADVISORY TO EXPIRE. WINDS HAVE DIMINISHED AND RUC SOUNDINGS SHOWING GRADUAL DECREASE IN WINDS THROUGH MIXED LAYER TODAY. STRONGEST PUSH OF COLD ADVECTION IS ALSO THROUGH FA AND ISALLOBARIC PRESSURE RISE MAXIMA EAST OF VALLEY AND WILL CONTINUE TO SHIFT EAST. WINDS WILL STILL BE IN THE 15 MPH RANGE WITH SURFACE PRESSURE GRADIENT HOWEVER NO RESTRICTION TO VSBY EXPECTED. AS FAR AS SNOW MAIN SHORTWAVE THROUGH FA WITH SURFACE LOW OVER WESTERN GREAT LAKES. STILL SEEING VSBY RESTRICTION TO -SN OVER MOST OB SITES EAST OF VALLEY. HAVE EXPANDED POPS WEST UP TO VALLEY AND CONTINUED INTO THE AFTERNOON AS LOWEST CONDENSATION PRESSURE DEFICITS AND MINOR ISENTROPIC LIFT CONTINUE INTO THE AFTERNOON IN CYCLONIC FLOW. TEMPERATURES NOT LIKELY TO RECOVER SIGNIFICANTLY TODAY AS LOW LEVEL WARM ADVECTION MINOR IN CONTINUED NORTHERLY FLOW. ONLY SUN EXPECTED TODAY IS OVER WESTERN FA AS RUC MAINTAINS LOW LEVEL RH (925-850MB) UP TO VALLEY AT 00Z. TEMPERATURE ADJUSTMENTS OVERALL WILL BE MINOR. && .AVIATION... MAINLY MVFR CIGS TO PERSIST FROM VALLEY EAST THROUGH MOST OF DAY AS RUC HOLDS LOW LEVEL INTEGRATED RH IN THROUGH 00Z. WINDS HAVE DIMINISHED BUT TO REMAIN FROM 15 TO 20KTS WITH PRESSURE GRADIENT. SNOW LIMITING VSBY TO <3 MILES WILL BE EAST OF VALLEY AND TO CONTINUE INTO THE AFTERNOON. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ VOELKER nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1029 AM EST SAT JAN 17 2009 .SYNOPSIS... ARCTIC HIGH PRESSURE WILL SLIDE OFF TO THE EAST TODAY. A LOW PRESSURE SYSTEM WILL THEN DROP DOWN ACROSS THE GREAT LAKES THIS AFTERNOON AND EVENING...BRINGING AN AREA OF SNOW. NORTHERLY FLOW OFF THE LAKES WILL KEEP A CHANCE OF SNOW INTO MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AREA OF ISENT LIFT NICELY DEFINED ON 280-285K RUC MOVING ACRS NRN FCST AREA ATTM. SEEING SOME FLURRIES AS THIS SHOT OF ISENT LIFT PASSES THRU...PROBABLY EVEN SEEING -SHSN WITHIN HEAVIER RETURNS OVER FAR NRN FCST AREA. ADDED SCHC -SHSN OVER FAR NORTH WITH POTENTIAL FOR FLURRIES FURTHER SOUTH. DEEPER ISENT LIFT SHIFTS EAST OF FCST AREA BY ERLY AFTN...WITH ANY -SHSN/FLURRIES DIMINISHING. SC DECK ASSOCD WITH ISENT LIFT WILL ALSO SHIFT EAST INTO AFTN HOURS...WITH A PREVAILING BKN MID LVL DECK FOR MUCH OF THE REST OF THE AFTN. CURRENT VIS SAT SHWNG A FAIR AMT OF CLEARING BACK ACRS SRN ILLINOIS AHEAD OF APPCHG COLD FRONT...AND POSSIBILITY TO SEE SOME SUN ACRS SRN FCST AREA LATER THIS AFTN. CHANCES FOR FLURRIES/ -SHSN WILL INCREASE FROM THE NORTHWEST BY ERLY EVNG AS SFC LO MOVES INTO WRN MICHIGAN WITH TRAILING COLD FRONT APPCHG WRN FCST AREA. TEMPS HAVE RECOVERED NICELY THIS MRNG FROM ANOTHER SUBZERO NIGHT FOR MANY. TEMPS HAD WARMED INTO THE HIGH SINGLE DIGITS AND TEENS ACRS FCST AREA AS SRLY FLO AND LO LVL WAA HAVE COMMENCED. WIND CHILLS HAVE LARGELY RISEN ABV -10F WITH WARMER TEMPS THIS MRNG...AND HAVE ALLOWED WIND CHILL ADV TO EXPIRE. WHILE EXPECT CONTINUED WARMING WITH WAA THIS AFTN...DROPPED HIGHS FROM ERLY MRNG FCST SVRL DEG...RANGING FROM L20S NORTH TO L30S SOUTH OF THE OHIO RIVER. ZONE AND GRID UPDATES OUT SHORTLY. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... CDFNT PUSHES ACROSS FA SAT NGT. GOOD LOW LEVEL CONVERGENCE AHEAD OF FNT. SINCE THE COLUMN WAS BEING SATURATED ON SAT...SHOULD SEE ENUF MOISTURE WITH FNT TO GET A PERIOD OF SNOW. WENT LIKELY IN THE NE...TAPERING DOWN TO CHC IN THE SW. ACCUMULATIONS OF AN INCH OR SO NOT OUT OF THE QUESTION FOR OUR FAR NORTHERN/ NORTHEAST COUNTIES....WITH GENERALLY LESS THAN AN INCH ELSEWHERE. H5 TROF WILL REMAIN IN PLACE ACROSS THE AREA SUNDAY INTO SUNDAY NIGHT. MODELS DROP ADDITIONAL ENERGY INTO TROF DURING THIS TIME PERIOD. WITH NLY CAA FLOW...SHOULD SEE A CHC OF SHSN. THERE IS A LITTLE MORE ORGANIZED S/W SUN NGT...THAT WILL PASS TO THE SSW OF THE FA AND IT MIGHT GIVE A BETTER CHC OF ORGANIZED SNOW TO THE SW SUN NGT. RIGHT NOW KEPT THE POPS AT 40 UNTIL THINGS COME A LITTLE CLEARER. AXIS OF H5 TROF TRIES TO WORK E ON MONDAY...BUT AND S/W DIVES INTO THE ERN US TROF..SO KEPT A CHC OF SHSN IN ON MONDAY. MAV TEMPS THRU THE PERIOD SEEMED REASONABLE...SO DIDNT STRAY TOO FAR. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... DEEP UPPER TROUGH WILL CONTINUE TO IMPACT THE EASTERN HALF OF THE CONTINENT EARLY NEXT WEEK...WITH NORTHERLY UPPER FLOW OVER THE OHIO VALLEY. MODELS DIFFER WITH RESPECT TO EMBEDDED SHORTWAVES IN THIS FLOW PATTERN...WITH NO REAL PREFERENCE TOWARD ONE MODEL OR THE OTHER. PERSISTENT UPPER TROUGH FINALLY BEGINS TO LIFT OUT LATE NEXT WEEK AS STRONG POSITIVE PNA PATTERN BREAKS DOWN. THIS BRINGS ZONAL FLOW...MODERATING TEMPERATURES AND LOW PRECIP CHANCES FOR THE LATTER HALF OF NEXT WEEK. 12Z GFS SUGGESTS A DEEPENING STORM SYSTEM MOVING INTO THE OHIO VALLEY LATE FRIDAY...BUT WITHOUT SUPPORT OF ITS PREVIOUS RUNS...ITS ENSEMBLE...OR THE ECMWF...THIS SOLN WAS IGNORED. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... SOUTHERLY WINDS WILL PICK UP TOWARDS DAYBREAK AS LOW PRESSURE STRENGTHENS...PIVOTING EAST THROUGH MICHIGAN TODAY. IN RESPONSE TO THE DEEPENING SURFACE LOW...WINDS WILL PICK UP AROUND THE 15 KT WITH HIGHER GUSTS TO 25 OR EVEN 30 KT RANGE. AS MORE MOIST AIR GETS PULLED IN AHEAD OF THE LOW...A COLD FRONT WILL WRING OUT THE SHOWERS AFTER ABOUT 0Z...PARTICULARLY OVER NRN CWA AND THE I-70 CORRIDOR. A BRIEF LOWERING OF CIGS WILL STILL REMAIN IN THE VFR CATEGORY AROUND 3500-4KFT A LITTLE AFTER DAYBREAK THIS MORNING AS A CONVERGENT FEATURE ANNOTATING STRONGER WINDS MOVES E THROUGH OHVLY. CIGS IN SNOW TONIGHT WILL DROP TO MVFR WITH OCCASIONAL IFR VSBYS. TOWARDS CMH AND DAY...THE CIGS MAY DROP BREIFLY TO IFR BUT THE STRONG WINDS SHOULD LIMIT THIS...AM CONTINUING TO LEAVE OUT OF THE FORECAST ATTM. BEHIND THE COLD FRONT AND BEYOND 24 HOURS...COLD AIR POOLING WILL HELP KEEP LOWER MVFR CIGS AND VSBYS IN OCCASIONAL LIGHT SNOW THROUGHOUT THE REGION. OUTLOOK...MVFR/IFR CEILINGS AND VISIBILITIES ARE POSSIBLE THROUGH SUNDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...SITES LONG TERM...HAWBLITZEL AVIATION...FRANKS oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 403 PM EST SAT JAN 17 2009 .SYNOPSIS... AS AN AREA OF HIGH PRESSURE BEGINS TO PUSH OFF TO THE EAST, LOW PRESSURE WILL BEGIN TO MOVE IN FROM THE GREAT LAKES REGION. THIS SYSTEM WILL BRING SNOW INTO REGION TONIGHT AND CONTINUING THROUGH THE DAY SUNDAY...WITH TEMPERATURES BEGINNING TO SLOWLY RISE THROUGH SUNDAY MORNING. AN UPPER LEVEL LOW WILL KEEP SCATTERED SNOW SHOWERS AROUND FOR MONDAY AND POSSIBLY INTO TUESDAY. && .NEAR TERM /UNTIL 10 PM THIS EVENING/... SATELLITE IMAGERY REVEALS ANOTHER VORTEX ROTATING SOUTHEAST TOWARD THE GREAT LAKES WITH AN INCREASING HIGH AND MID LEVEL CLOUDS STREAMING INTO EASTERN NEW YORK AND WESTERN NEW ENGLAND. OVERALL TRENDS ON THE IR IMAGERY SUGGEST CLOUD TOP WARMING AND UPSTREAM RADAR SHOWING A BROKEN PRECIP PATTERN WITH SNOWFALL REPORTS ON THE ORDER OF 1-3 INCHES. SO THROUGH THIS EVENING...LATEST RUC13 AND ASSOCIATED SOUNDINGS SHOW THE HIGH AND MID LEVEL MOISTURE QUICKLY INCREASING BUT REMAINING DRY IN THE LOWER LEVELS. TOWARD 03Z /10PM/ THE COLUMN IN THE LOWER LEVELS MOISTENS UP FOR AN INCREASED CHANCE FOR LIGHT SNOW TO DEVELOP WEST OF THE HUDSON RIVER. WITH THE CLOUD COVER INCREASING...TEMPS MAY FALL SLIGHTLY THIS EVENING BEFORE A STEADY OR SLOW RISE OCCURS WITH THE INCREASE IN WARM ADVECTION. && .SHORT TERM /10 PM THIS EVENING THROUGH MONDAY NIGHT/... THE AFOREMENTIONED INCREASE IN WARM ADVECTION IS WELL SEEN IN THE 850MB THERMAL ADVECTION DELTA CHANGE WITH GREATER THAN 40 KNTS SOUTHERLY WINDS SEEN ON THE SURFACE. ISENTROPIC ANALYSIS ON THE 285K SURFACE ALSO SUPPORTS IMPRESSIVE UPGLIDE WITH NET ADIABATIC ISENTROPIC OMEGA SIGNALING STRONG LIFT AND SNOW TO DEVELOP RATHER QUICKLY OVERNIGHT. SPECIFIC HUMIDITIES OF 1-2 G/KG ON THE 285K SURFACE COINCIDING WITH THE LIFT SUPPORT A GENERAL 1 TO 3 INCHES ACROSS THE REGION BEFORE SUNRISE SUNDAY MORNING AS SNOW RATIOS SHOULD BE CLOSE TO 20:1. BEST UPPER JET SUPPORT IS EXPECTED TO BE IN THE REGION SUNDAY MORNING WITH STILL STRONG ISENTROPIC UPGLIDE AND 2-3 G/KG SEEN ON THE SURFACE. THE HIGHER SPECIFIC HUMIDITIES SLIDE EAST ACROSS ADJACENT NEW ENGLAND WHERE SNOWFALL TOTALS COULD RANGE BETWEEN 2-4" EVEN THOUGH SNOW RATIOS WILL BE DECLINING THROUGH THE DAY. THIS IS WHERE WE WILL PLACE THE WINTER WEATHER ADVISORY FOR SNOW AT THIS TIME SINCE IT WILL OCCUR WITHIN 12-18 HOURS. FOR NY COUNTIES...SNOW WILL BECOME INTERMITTENT AS MID LEVEL DRY SLOT APPROACHES CUTTING OFF FAVORABLE PROFILE FOR SNOW SO ONLY AN ADDITIONAL 1 TO 3 INCHES EXPECTED /THE HIGHER TOTALS EXPECTED ACROSS THE HIGHER ELEVATION/ AND NO HEADLINES AT THIS TIME. THIS WAS COORDINATED WITH ADJACENT WFOS. AS MAIN UPPER TROUGH REMAINS TO THE WEST...ADDITIONAL SHORT WAVE ENERGY ROTATES AROUND THE BASE OF THE TROUGH ACROSS THE TENNESSEE VALLEY WITH SECONDARY CYCLOGENESIS OFF THE MID ATLANTIC COAST SUNDAY EVENING. TRENDS FROM THE LATEST GLOBAL MODELS AND ENSEMBLE MEMBERS TRACK THIS SURFACE LOW FAR ENOUGH TO THE EAST LEAVING A CUL-REGION ACROSS NY WITH AN INVERTED SURFACE TROUGH ACROSS THE REGION. THIS SHOULD PROVIDE ISOLATED TO SCATTERED SNOW SHOWERS FOR THE REGION. WE WILL CONTINUE TO MONITOR TRENDS FOR OUR ADJACENT NEW ENGLAND COUNTIES IF ATLANTIC MOISTURE IS ABLE TO INFILTRATE FURTHER INLAND FOR ADDITIONAL SNOW. THE UPPER TROUGH AND ELONGATED DEFORMATION AXIS WILL BE SITUATED OVER NY STATE THROUGH THE DAY MONDAY. THIS SHOULD TOUCH OFF ADDITIONAL SNOW SHOWERS FOR THE REGION. WILL NEED TO WATCH MESOSCALE IMPACTS ACROSS THE REGION WITH SMALL POTENTIAL FOR MOHAWK-HUDSON VALLEY CONVERGENCE. ACTIVITY BEGINS TO WIND DOWN MONDAY NIGHT WITH THE SLOW DEPARTURE OF THIS UPPER TROUGH AND MAIN SURFACE LOW WELL TO THE NORTHEAST OF THE REGION. && .LONG TERM /TUESDAY THROUGH SATURDAY/... LAKE EFFECT EXPECTED TO START OFF THE PERIOD WITH SLGT CHC TO CHC POPS. TUE MAX TEMPS IN M20S IN THE VALLEYS AND MID TEENS IN THE HIGHER TERRAIN. MIN TEMPS TUE NT WILL BE IN THE SINGLE DIGITS IN THE VALLEYS AND NEGATIVE SINGLE DIGITS IN THE HIGHER TERRAIN. ANOTHER SHORTWAVE WILL MOVE THROUGH WEDNESDAY NIGHT THROUGH THURSDAY WITH GUSTY WINDS AND MORE SNOW SHOWERS. MORE LAKE EFFECT POSSIBLE IN EXTREME NW PORTIONS OF CWA IN THE WAKE OF THIS SHORTWAVE. WED MAX TEMPS WILL BE IN THE L20S IN THE VALLEYS AND MID TEENS IN THE HIGHER TERRAIN. WED NT LOW WILL BE AROUND 10 IN THE VALLEYS AND NEAR ZERO IN THE HIGHER TERRAIN. THURSDAY WILL EXPERIENCE SOME WAA AHEAD OF THE SHORTWAVE WITH MAX TEMPS NEAR 30 IN THE VALLEYS AND M20S IN THE HIGHER TERRAIN. THURSDAY NT MIN TEMPS IN THE MID TEENS IN THE VALLEYS AND SINGLE DIGITS IN THE HIGHER TERRAIN. NEXT SYSTEM TO AFFECT OUR AREA HAS ECMWF AND GFS IN DISAGREEMENT OF TIMING AND SPEED. ECMWF HAVE A MORE NORTHERLY AND QUICKER TRACK WITH THE LOW CENTER NORTH OF LAKE ONTARIO BY 12Z/FRI. WHILE GFS HAS THE SFC LOW OVER LAKE MICHIGAN AT 12Z/FRI. BOTH MODELS DO HAVE PRECIP AFFECTING EASTERN NY BY 18Z/FRI. GFS FOLLOWS SIMILAR TRACK TO ECMWF WITH LOW ENTERING CANADIAN MARITIMES SATURDAY INTO SATURDAY NIGHT. MAX TEMPS FRI AND SAT WILL BE IN THE M20S IN THE VALLEYS AND MID TEENS IN THE HIGHER TERRAIN. MIN TEMPS WILL BE IN THE SINGLE DIGITS IN THE VALLEYS AND DOWN TO -10 DEGREES IN THE HIGHER TERRAIN. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... VFR CONDITIONS EXPECTED THROUGH THIS EVENING AS HIGH PRESSURE CONTINUES TO SLIDE EAST ACROSS THE REGION. HIGH LEVEL CIRRUS WAS MOVING IN RAPIDLY FROM THE WEST...AND SHOULD JUST ABOUT COVER THE SKIES OF ALL THREE AIRPORTS BY SUNDOWN. LOW PRESSURE OVER THE WESTERN GREAT LAKES WILL TRACK SLOWLY EAST...SPREADING MAINLY LIGHT SNOW ACROSS THE AIRPORTS BEGINNING SHORTLY AFTER MIDNIGHT /06Z/. BY 08Z...ALL LOCATIONS ARE DOWN TO MVFR CIGS/VSBY...BOTTOMING OUT AT IFR BY DAYBREAK. THE ACTIVITY WILL SLOWLY BEGIN TO WIND DOWN AFTER 18Z AS A COASTAL LOW DEVELOPS OFF THE DELMARVA AND LIFTS QUICKLY NORTH TO MAINE. THIS LOW WILL DRAW MUCH OF THE ENERGY AWAY FROM THE INITIAL SYSTEM...BUT WRAPAROUND FROM THE COMBINED SYSTEM AS IT DEPARTS KEEPS A CHC OF -SHSN IN REACH. A WELL-SHEARED NORTHWESTERLY FLOW SETS UP BY LATE MON...PRECLUDING ANY LAKE EFFECT FROM DEVELOPING. SURFACE WINDS BECOME MORE NORTHWESTERLY...BUT LIGHT...BY WED...WITH A RETURN TO A SOUTHWEST FLOW AS A HIGH PRESSURE RIDGE BUILDS QUICKLY UP ALONG THE APPALACHIANS. OUTLOOK.... SUN PM...MVFR/IFR IMPROVING TO VFR SLGT CHC -SHSN. MON...MVFR SCT -SHSN. MON NGT-WED...VFR...NO SIG WX. && .HYDROLOGY... SEVERAL RIVER GAGES HAVE BEEN EXHIBITING ICE EFFECTS...WITH MOST LEVELS GENERALLY HOLDING STEADY...OR FALLING SLIGHTLY. THE ONLY HYDROLOGY PROBLEMS EXPECTED THROUGH EARLY NEXT WEEK WOULD BE A FEW ISOLATED FRAZIL ICE/FREEZE UP RIVER ICE JAMS. THE ALBANY NWS CRITERIA FOR POSSIBLE RIVER ICE FREEZE UP JAMS IS THREE CONSECUTIVE DAYS WITH DAILY AVERAGE TEMPERATURES OF ZERO DEGREES FAHRENHEIT OR LESS. THIS COLD IS POSSIBLE FROM THE NORTHERN CATSKILLS NORTH ACROSS THE MOHAWK VALLEY TO THE SOUTHERN ADIRONDACKS. HIGHER ELEVATION BASINS IN SOUTHERN VERMONT AND NORTHERN BERKSHIRE COUNTY MASSACHUSETTS MAY ALSO BE COLD ENOUGH TO SEE A RANDOM RIVER FREEZE UP JAM. COLD WEATHER IS EXPECTED TO CONTINUE INTO NEXT WEEK WITH ANY PRECIPITATION COMING AS SNOW. RIVER ICE WILL THEREFORE CONTINUE TO THICKEN. SOME RIVER STAGES AND FLOWS WILL CONTINUE TO SHOW LARGE FLUCTUATIONS OR RISES DUE TO ICE EFFECTS. THE SNOWPACK...WHICH COVERS OUR ENTIRE HSA...IS EXPECTED TO CONTINUE TO INCREASE IN WATER CONTENT ON SUNDAY. FOR DETAILS ON THE RIVERS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST SUNDAY FOR CTZ001-013. NY...NONE. MA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST SUNDAY FOR MAZ001-025. VT...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM EST SUNDAY FOR VTZ013>015. && $$ SYNOPSIS...MHD/BGM NEAR TERM...BGM SHORT TERM...BGM LONG TERM...KGS AVIATION...ELH HYDROLOGY...SND/11 FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE NORTH PLATTE NE 1140 AM CST SAT JAN 17 2009 .UPDATE... AS TEMPERATURES CLIMB STRONGER WINDS HAVE BEGAN TO MIX DOWN TO WIND ADVISORY CRITERIA. THE RUC MODEL INDICATES THE STRONGER WINDS TO CONTINUE THROUGH 21Z WITH THE WIND ADVISORY EXPANDED EASTWARD ACROSS NORTH CENTRAL NEBRASKA THROUGH 4 PM CST. OTHERWISE FORECAST ON TRACK. && .PREV DISCUSSION... /ISSUED 309 AM CST SAT JAN 17 2009/ DISCUSSION... HIGH AMPLITUDE PATTERN IN PLACE WITH WEST COAST RIDGE WILL INTO AK AND TROF BRINING COLD AIR INTO SE CONUS. NEXT CLIPPER SHOWING UP NICELY IN H2O MOVING THROUGH NORTHERN PLAINS AND HEADED TOWARD UPPER MIDWEST. THIS IN COMBINATION WITH TROF MOVING INTO EPAC WILL BRING MORE OF A MERIDIONAL TILT TO UPPER PATTERN WITH RIDGE MOVING MORE OVER THE INTERMOUNTAIN WEST AND WESTERN CANADA AND WELL CARVED OUT TROF FROM MO RIVER EASTWARD. THIS LOOKS TO BRING A SHARP CONTRAST TO TEMPERATURES ACROSS LBF CWA OVER NEXT FEW DAYS...THOUGH DRY CONDITIONS LOOK TO REMAIN IN PLACE. SFC ANALYSIS SHOWING LOW AHEAD OF CLIPPER PROGESSING INTO WESTERN GREAT LAKES ATTM AND PULLING TROF/WARM FRONT FARTHER EAST. COOLER AIR WRAPPING BEHIND THE CLIPPER ALONG WITH THE USUAL STRONG WINDS...BUT LUCKILY THIS AIRMASS HAS BEEN MODIFIED ENOUGH THAT TEMPS WILL BE COOLER THAN THOSE ON FRIDAY...BUT STILL SHOULD END UP ABOVE NORMAL. MAIN CONCERN TODAY WILL BE WINDS ASSOC WITH THIS CAA. FAIRLY STRONG LLVL WINDS MIXING DOWN ATTM WITH GUSTS NEAR 40KTS FROM VTN TO ICR AND SOME OVER 50KTS IN THE NOW PANHANDLE. THESE WINDS STAY STRONG THROUGH THE EALRY AFTERNOON BEFORE TAPERING OFF SOME. CAA WILL BE LESSENING ALONG WITH PRESS GRAD AND HAVE A HARD TIME ISSUING WIND HEADLINES OVER MUCH OF CWA...THOUGH SOME SITES MAY CONTINUE NEAR THIS CRIT THROUGH THE MORNING ACROSS SOUTHERN PANHANDLE SO HAVE PLACE ADV IN FOR DEUEL AND GARDEN COUNTIES. PRESS COUPLET STRONGEST ATTM AND COULD ALSO BE REASON FOR GUSTS UP NORTH AND WILL CONTINUE TO MONITOR TRENDS NEXT COUPLE HOURS. VISIBLE PICS EALIER SHOWED QUICK END TO SNOWPACK ACROSS WESTERN NEB ON FRIDAY WHICH NEW NAM SLOW TO PICK UP ON BUT BELIEVE MAV GUIDANCE TOO WARM AND HAVE USED BLEND WHICH WAS CLOSE TO PREV FORECAST OF MID 30S NORTHEAST TO LOWER 50S SOUTHWEST. THERE LOOKS TO BE A GRADUAL AND WELCOME WARMUP SUNDAY INTO EARLY NEXT WEEK AS THE RIDGE REMAIN IN PLACE ACROSS THE WEST BEFORE BREAKING DOWN ON WEDNESDAY. THIS DRY NORTHERLY FLOW AND WARMING TEMPS SHOULD BRING FIRE WX CONCERN TO THE FRONT. THIS WILL HAVE TO BE MONTIORED DAILY...ESPECIALLY FOR DEW POINT TRENDS/VERIFICATION TO MODEL AND GUIDANCE AS BREEZY CONDITIONS SHOULD BE IN PLACE ACROSS THE WEST MOST OF THE NEXT SEVERAL DAYS. MAIN CONCERN WILL BE SOUTHERN PANHANDLE INTO THE SOUTHWEST...THIS WILL BE HIGHLIGHTED IN THE HWO ATTM AS CRITICAL NUMBERS LOOK TO BE OUT OF REACH ATTM...BUT ONLY SLIGHT ADJUSTMENTS OF TEMPERATURE OR DEW POINTS WILL PUSH THIS INTO THE HEADLINE TERRITORY...AND WITH RIDGE BREAKING DOWN ON WED THIS MAY BE THE DAY TO WATCH. AVIATION... LOW CEILINGS OR VISIBILITY ARE NOT EXPECTED IN WESTERN AND NORTH CENTRAL NEBRASKA BEFORE SATURDAY NIGHT. THE GLOBAL MODEL IS SHOWING SOME HIGH RELATIVE HUMIDITY AT 900MB IN NORTH CENTRAL NEBRASKA NORTH AND EAST OF A VTN-BBW LINE...SO THERE IS A POSSIBILITY OF INSTRUMENT CEILINGS IN THAT AREA. HOWEVER...THE NORTH AMERICAN MODEL SHOWS THE HIGHER RH EAST OF ONL. OUR CONFIDENCE IS NOT HIGH IN THE LOW CEILINGS...SO WE WILL NOT INCLUDE A MENTION OF IT IN THE TERMINAL FORECASTS FOR VALENTINE AND NORTH PLATTE. WITH NORTH TO NORTHWEST WIND 20-30 KTS AND GUSTY...SOME WIND IMPACTS ARE LIKELY AROUND WESTERN AND NORTH CENTRAL NEBRASKA... ESPECIALLY FOR SMALL TO MEDIUM SIZED AIRCRAFT. AT LBF...IT WILL AFFECT RUNWAY CONFIGURATION...BUT IS NOT LIKELY TO PRODUCE SERIOUS CROSS-WIND EFFECTS. FIRE WEATHER... WITH TEMPERATURES WARMING IN WESTERN AND NORTH CENTRAL NEBRASKA SUNDAY THROUGH WEDNESDAY...THERE IS POTENTIAL FOR SOME VOLATILE FIRE CONDITIONS. IN THE WEST AND SOUTHWEST...RELATIVE HUMIDITY IS LIKELY TO BE LESS THAT 20 PERCENT...AND WIND MAY REACH CRITERIA SUNDAY AFTERNOON. HOWEVER...THE RELATIVE HUMIDITY IS LIKELY TO BE AT ITS LOWEST OF 15 TO 20 PERCENT TUESDAY. THEREFORE...SINCE THE WIND AND RELATIVE HUMIDITY CRITERIA DO NOT APPEAR TO COME TOGETHER...WE WILL NOT HAVE ANY FIRE HEADLINES. WE ARE LOOKING AT A MENTION OF THE DRY CONDITIONS IN THE HAZARDOUS WEATHER OUTLOOK THOUGH. && .LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY UNTIL 4 PM CST /3 PM MST/ THIS NEZ005>010-022>029-035>038-056>059-069>071-094. && $$ UPDATE...KECK SHORT TERM/EXTENDED...13 AVIATION...KECK ne