AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 550 PM EST MON FEB 27 2006 .AVIATION... AREAS OF MVFR CIGS/VSBYS CONTINUE FROM DTW SOUTHWARD IN REGION OF WEAK MID LEVEL THERMAL CONVERGENCE AND IN RIGHT REAR QUADRANT OF DEPARTING UPPER JET. THIS AREA WILL SLOWLY DIMINISH AS WEAK FORCING MOVES SOUTHEAST OF THE REGION AROUND 04-06Z. OTHERWISE VFR CONDITIONS TO PREVAIL ACROSS THE ENTIRE REGION WITH LIGHT WINDS AS SURFACE HIGH CONTINUES TO BUILD INTO THE REGION. DRY AIR UPSTREAM...BOTH SURFACE AND ALOFT...WILL HELP ERODE MVFR CLOUD SHIELD OVER DTW AREA AS WELL THIS EVENING...WITH UPSTREAM SURFACE DEW POINTS ALREADY IN THE SINGLE DIGITS. ANTICIPATE ONLY A RETURN OF MID LEVEL CLOUDS TUESDAY AFTERNOON AS WARM AIR ADVECTION KICKS IN. 850 MB TEMPERATURES RISE TO NEAR ZERO BY 00Z...WHICH WILL KEEP LAKE STRATOCU OUT OF THE REGION. && .SHORT TERM...TONIGHT AND TUESDAY THE SNOW FROM THIS MORNING WAS A COMBINATION OF SEVERAL FACTORS THAT INCLUDED A FAVORABLE UPPER JET POSITION (ENTRANCE REGION), 850MB 2-D FRONTOGENESIS, LAKE MICHIGAN CONTRIBUTION AS DELTA T/S WERE A BIT HIGHER THAN PROGGED AND SURFACE CONVERGENCE FROM FAST MOVING SURFACE LOW ACROSS LAKE HURON AND TAILING FRONT SWINGING SOUTH ACROSS THE CWA. IN FACT...IR SATELLITE IMAGERY SUGGESTED A BAROCLINIC LEAF DEVELOPING IN ADVANCE OF SHORT WAVE ACROSS WISCONSIN THIS MORNING THAT QUICKLY MOVED ACROSS OUR REGION LATE THIS MORNING. SO ALL THESE FACTORS ENHANCED OUR SNOWFALL THIS MORNING WITH ABOUT 1 INCH ACROSS THE SOUTHERN 2/3RDS OF THE CWA. THE REMNANTS OF THESE AFOREMENTIONED FEATURES IS STILL OCCURRING SOUTH OF 8-MILE ROAD WITH HINTS OF SOME FGEN SEEN ON THE KGRR 88D. LATEST RUC SUGGESTS THIS WILL QUICKLY DEPART TO OUR SOUTHEAST BEFORE SUNSET AS LOW LEVEL DRY AIR FILTERS SOUTH AS SURFACE HIGH OOZES SOUTHEAST ACROSS THE GREAT LAKES. SO COMBINE THAT WITH LOSS OF DIURNAL COMPONENT...SKY COVER SHOULD GRADUALLY CLEAR OUT AND THIS SHOULD SET UP FOR ALMOST IDEAL RADIATIONAL COOLING OVERNIGHT. WITH UPSTREAM DEWPOINTS INTO THE SINGLE DIGITS...WE WILL UNDERCUT GUIDANCE BY SEVERAL DEGREES WITH SINGLE DIGITS OUTSIDE OF METRO DETROIT. THE SURFACE RIDGE WILL BE OVER THE REGION ON TUESDAY YET UPSTREAM MID LEVEL WARM ADVECTION WILL BE TAKING PLACE. THIS SHOULD RESULT IN AN AC-DECK AS 300MB JET INCREASES DUE TO THE INCREASING THERMAL GRADIENT TO AID IN ADDITIONAL LIFT. THIS IN TURN WOULD HOLD DOWN SURFACE TEMPS SOMEWHAT AS NAMX WOULD SUGGEST AND WE WILL FOLLOW THIS ALONG WITH A BLEND OF THE MAV/MET NUMBERS. && .LONG TERM...TUESDAY NIGHT THROUGH MONDAY THE WEATHER THIS WEEK WILL BE IMPACTED BY WAVES EJECTING OUT OF THE CLOSED LOW OFF THE PACIFIC COAST AND THE INTERACTION WITH UPPER LOW OVER EASTERN CANADA. THE FIRST SUCH WAVE TO WATCH WILL MOVE AROUND THE RIDGE OVER THE WESTERN STATES TUESDAY NIGHT AND WEDNESDAY. THE LATEST MODELS INDICATE THIS WAVE WILL MOVE ACROSS THE GREAT LAKES REGION WEDNESDAY NIGHT...NOT PHASING WITH ANOTHER WAVE MOVING AROUND THE UPPER LOW OVER QUEBEC ON THURSDAY. A LOW PRESSURE SYSTEM WILL DEVELOP AHEAD OF THIS WAVE OVER THE PLAINS AND IS EXPECTED TO TRACK ALONG OR JUST SOUTH OF THE MICHIGAN BORDER WEDNESDAY NIGHT. AS THIS WAVE APPROACHES ON WEDNESDAY...THE BAROCLINIC ZONE WILL LIFT NORTH OVER LOWER MICHIGAN WITH GOOD ISENTROPIC LIFT INTO THE OVERNIGHT HOURS. DESPITE THIS LIFT...FEEL THE GFS IS TOO FAST TO MOISTEN THE LOW LAYERS. THE GFS WHICH SHOWS CONSIDERABLY MORE QPF FOR WEDNESDAY DOES NOT SHOW THE 275K ISENTROPIC SURFACE DROPPING BELOW 15MB DURING THE AFTERNOON. HAVE THEREFORE CONTINUED WITH ONLY CHANCE POPS AND DELAYED THE ONSET OF PRECIP ACROSS THE NORTHERN CWA UNTIL THE AFTERNOON. PRECIP TYPE WILL ALSO BE A CONCERN BOTH WEDNESDAY AND WEDNESDAY NIGHT. HAVE LEFT CHANCE OF FREEZING RAIN AND SNOW IN FOR THE NORTHERN DETROIT SUBURBS AND FURTHER NORTH BOTH WEDNESDAY AND WEDNESDAY NIGHT ALTHOUGH WEDNESDAY NIGHT IS CERTAINLY A GREATER CONCERN. ANY FROZEN PRECIPITATION THAT FALLS WEDNESDAY AFTERNOON IS EXPECTED TO BE BRIEF WITH THE BOUNDARY LAYER WARMING AND CAUSING A CHANGE-OVER TO ALL RAIN IN MOST LOCATIONS BY LATE AFTERNOON. BY WEDNESDAY NIGHT THE GFS IS SLIGHTLY STRONGER THAN MOST OF THE OTHER MODELS WITH THE STRENGTH OF THE UPPER LEVEL WAVE. BECAUSE OF THIS...PREFER TO LEAN TOWARDS THE THERMAL PROFILE OF THE NAM WHICH IS SLOWER FOR COLD AIR ADVECTION TO INCREASE. THIS MEANS THERE MAY BE A GOOD PERIOD OF FREEZING RAIN BEFORE CHANGING BACK OVER TO ALL SNOW. PRECIP WILL LIKELY FALL AS RAIN AS FAR NORTH AS THE I-69 CORRIDOR THROUGH A PORTION OF THE EVENING BEFORE TEMPS START TO FALL MAKING FREEZING RAIN THE CONCERN OVERNIGHT. QPF BETWEEN ONE AND TWO TENTHS OF AN INCH COULD CAUSE SIGNIFICANT ICING OVERNIGHT ON WEDNESDAY. IT LOOKS LIKE THE MAJORITY OF THE FREEZING RAIN WILL BE NORTH OF I-96 BEFORE PRECIP EVENTUALLY CHANGES OVER TO LIGHT SNOW. THIS FAVORABLE AREA FOR FREEZING RAIN IS SUBJECT TO CHANGE AS MODELS CONVERGE ON A SIMILAR THERMAL PROFILE AND TRACK OVER THE NEXT TWO DAYS. BY THIS WEEKEND...MODELS ALL INDICATE THAT THE UPPER LEVEL RIDGE WILL BUILD OVER THE WESTERN GREAT LAKES FRIDAY AND SATURDAY WITH HIGH PRESSURE AT THE SURFACE. WILL CONTINUE WITH DRY FORECAST THROUGH SATURDAY AFTERNOON BUT WILL THEN HAVE TO START WATCHING FOR WARM ADVECTION PRECIP THAT WILL APPROACH FROM THE WEST. ENERGY EJECTING OUR OF THE UPPER LOW OVER THE WEST COAST WILL CAUSE A LOW PRESSURE SYSTEM TO DEVELOP IN THE LEE OF THE ROCKIES. MODELS OFFER A VARIETY OF SOLUTIONS ABOUT THE TRACK OF THIS SYSTEM...RANGING FROM A SOUTHERN TRACK ACROSS KANSAS ON THE 00Z/06Z/27 GFS TO A MORE NORTHERN TRACK ACROSS SOUTH DAKOTA ON THE 00Z/27 ECMWF. THESE VARIATIONS IN TRACK WILL HAVE A SIGNIFICANT IMPACT ON BOTH TEMPERATURES AND PRECIPITATION TYPE FOR LOWER MICHIGAN. 12Z/27 GFS HAS TRENDED TOWARDS THE 00Z/27 ECMWF AND WILL HEDGE FORECAST TOWARDS A BLEND OF THESE TWO MODELS. ALSO PREFER THIS IDEA WITH MODELS SHOWING MORE ENERGY DROPPING DOWN THE BACKSIDE OF THE UPPER LOW ON FRIDAY NIGHT. CHANGES TO THE GOING FORECAST INCLUDED ADDING A CHANCE OF SNOW TO THE TRI CITIES SATURDAY NIGHT AND RAISING TEMPS A COUPLE DEGREES FOR SUNDAY AND MONDAY. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HU LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BGM LONG TERM....KEK AVIATION.....GSS YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 440 PM EST MON FEB 27 2006 .SHORT TERM...TONIGHT AND TUESDAY THE SNOW FROM THIS MORNING WAS A COMBINATION OF SEVERAL FACTORS THAT INCLUDED A FAVORABLE UPPER JET POSITION (ENTRANCE REGION), 850MB 2-D FRONTOGENESIS, LAKE MICHIGAN CONTRIBUTION AS DELTA T/S WERE A BIT HIGHER THAN PROGGED AND SURFACE CONVERGENCE FROM FAST MOVING SURFACE LOW ACROSS LAKE HURON AND TAILING FRONT SWINGING SOUTH ACROSS THE CWA. IN FACT...IR SATELLITE IMAGERY SUGGESTED A BAROCLINIC LEAF DEVELOPING IN ADVANCE OF SHORT WAVE ACROSS WISCONSIN THIS MORNING THAT QUICKLY MOVED ACROSS OUR REGION LATE THIS MORNING. SO ALL THESE FACTORS ENHANCED OUR SNOWFALL THIS MORNING WITH ABOUT 1 INCH ACROSS THE SOUTHERN 2/3RDS OF THE CWA. THE REMNANTS OF THESE AFOREMENTIONED FEATURES IS STILL OCCURRING SOUTH OF 8-MILE ROAD WITH HINTS OF SOME FGEN SEEN ON THE KGRR 88D. LATEST RUC SUGGESTS THIS WILL QUICKLY DEPART TO OUR SOUTHEAST BEFORE SUNSET AS LOW LEVEL DRY AIR FILTERS SOUTH AS SURFACE HIGH OOZES SOUTHEAST ACROSS THE GREAT LAKES. SO COMBINE THAT WITH LOSS OF DIURNAL COMPONENT...SKY COVER SHOULD GRADUALLY CLEAR OUT AND THIS SHOULD SET UP FOR ALMOST IDEAL RADIATIONAL COOLING OVERNIGHT. WITH UPSTREAM DEWPOINTS INTO THE SINGLE DIGITS...WE WILL UNDERCUT GUIDANCE BY SEVERAL DEGREES WITH SINGLE DIGITS OUTSIDE OF METRO DETROIT. THE SURFACE RIDGE WILL BE OVER THE REGION ON TUESDAY YET UPSTREAM MID LEVEL WARM ADVECTION WILL BE TAKING PLACE. THIS SHOULD RESULT IN AN AC-DECK AS 300MB JET INCREASES DUE TO THE INCREASING THERMAL GRADIENT TO AID IN ADDITIONAL LIFT. THIS IN TURN WOULD HOLD DOWN SURFACE TEMPS SOMEWHAT AS NAMX WOULD SUGGEST AND WE WILL FOLLOW THIS ALONG WITH A BLEND OF THE MAV/MET NUMBERS. && .LONG TERM...TUESDAY NIGHT THROUGH MONDAY THE WEATHER THIS WEEK WILL BE IMPACTED BY WAVES EJECTING OUT OF THE CLOSED LOW OFF THE PACIFIC COAST AND THE INTERACTION WITH UPPER LOW OVER EASTERN CANADA. THE FIRST SUCH WAVE TO WATCH WILL MOVE AROUND THE RIDGE OVER THE WESTERN STATES TUESDAY NIGHT AND WEDNESDAY. THE LATEST MODELS INDICATE THIS WAVE WILL MOVE ACROSS THE GREAT LAKES REGION WEDNESDAY NIGHT...NOT PHASING WITH ANOTHER WAVE MOVING AROUND THE UPPER LOW OVER QUEBEC ON THURSDAY. A LOW PRESSURE SYSTEM WILL DEVELOP AHEAD OF THIS WAVE OVER THE PLAINS AND IS EXPECTED TO TRACK ALONG OR JUST SOUTH OF THE MICHIGAN BORDER WEDNESDAY NIGHT. AS THIS WAVE APPROACHES ON WEDNESDAY...THE BAROCLINIC ZONE WILL LIFT NORTH OVER LOWER MICHIGAN WITH GOOD ISENTROPIC LIFT INTO THE OVERNIGHT HOURS. DESPITE THIS LIFT...FEEL THE GFS IS TOO FAST TO MOISTEN THE LOW LAYERS. THE GFS WHICH SHOWS CONSIDERABLY MORE QPF FOR WEDNESDAY DOES NOT SHOW THE 275K ISENTROPIC SURFACE DROPPING BELOW 15MB DURING THE AFTERNOON. HAVE THEREFORE CONTINUED WITH ONLY CHANCE POPS AND DELAYED THE ONSET OF PRECIP ACROSS THE NORTHERN CWA UNTIL THE AFTERNOON. PRECIP TYPE WILL ALSO BE A CONCERN BOTH WEDNESDAY AND WEDNESDAY NIGHT. HAVE LEFT CHANCE OF FREEZING RAIN AND SNOW IN FOR THE NORTHERN DETROIT SUBURBS AND FURTHER NORTH BOTH WEDNESDAY AND WEDNESDAY NIGHT ALTHOUGH WEDNESDAY NIGHT IS CERTAINLY A GREATER CONCER. ANY FROZEN PRECIPITATION THAT FALLS WEDNESDAY AFTERNOON IS EXPECTED TO BE BRIEF WITH THE BOUNDARY LAYER WARMING AND CAUSING A CHANGE-OVER TO ALL RAIN IN MOST LOCATIONS BY LATE AFTERNOON. BY WEDNESDAY NIGHT THE GFS IS SLIGHTLY STRONGER THAN MOST OF THE OTHER MODELS WITH THE STRENGTH OF THE UPPER LEVEL WAVE. BECAUSE OF THIS...PREFER TO LEAN TOWARDS THE THERMAL PROFILE OF THE NAM WHICH IS SLOWER FOR COLD AIR ADVECTION TO INCREASE. THIS MEANS THERE MAY BE A GOOD PERIOD OF FREEZING RAIN BEFORE CHANGING BACK OVER TO ALL SNOW. PRECIP WILL LIKELY FALL AS RAIN AS FAR NORTH AS THE I-69 CORRIDOR THROUGH A PORTION OF THE EVENING BEFORE TEMPS START TO FALL MAKING FREEZING RAIN THE CONCERN OVERNIGHT. QPF BETWEEN ONE AND TWO TENTHS OF AN INCH COULD CAUSE SIGNIFICANT ICING OVERNIGHT ON WEDNESDAY. IT LOOKS LIKE THE MAJORITY OF THE FREEZING RAIN WILL BE NORTH OF I-96 BEFORE PRECIP EVENTUALLY CHANGES OVER TO LIGHT SNOW. THIS FAVORABLE AREA FOR FREEZING RAIN IS SUBJECT TO CHANGE AS MODELS CONVERGE ON A SIMILAR THERMAL PROFILE AND TRACK OVER THE NEXT TWO DAYS. BY THIS WEEKEND...MODELS ALL INDICATE THAT THE UPPER LEVEL RIDGE WILL BUILD OVER THE WESTERN GREAT LAKES FRIDAY AND SATURDAY WITH HIGH PRESSURE AT THE SURFACE. WILL CONTINUE WITH DRY FORECAST THROUGH SATURDAY AFTERNOON BUT WILL THEN HAVE TO START WATCHING FOR WARM ADVECTION PRECIP THAT WILL APPROACH FROM THE WEST. ENERGY EJECTING OUR OF THE UPPER LOW OVER THE WEST COAST WILL CAUSE A LOW PRESSURE SYSTEM TO DEVELOP IN THE LEE OF THE ROCKIES. MODELS OFFER A VARIETY OF SOLUTIONS ABOUT THE TRACK OF THIS SYSTEM...RANGING FROM A SOUTHERN TRACK ACROSS KANSAS ON THE 00Z/06Z/27 GFS TO A MORE NORTHERN TRACK ACROSS SOUTH DAKOTA ON THE 00Z/27 ECMWF. THESE VARIATIONS IN TRACK WILL HAVE A SIGNIFICANT IMPACT ON BOTH TEMPERATURES AND PRECIPITATION TYPE FOR LOWER MICHIGAN. 12Z/27 GFS HAS TRENDED TOWARDS THE 00Z/27 ECMWF AND WILL HEDGE FORECAST TOWARDS A BLEND OF THESE TWO MODELS. ALSO PREFER THIS IDEA WITH MODELS SHOWING MORE ENERGY DROPPING DOWN THE BACKSIDE OF THE UPPER LOW ON FRIDAY NIGHT. CHANGES TO THE GOING FORECAST INCLUDED ADDING A CHANCE OF SNOW TO THE TRI CITIES SATURDAY NIGHT AND RAISING TEMPS A COUPLE DEGREES FOR SUNDAY AND MONDAY. && .PREV DISCUSSION...ISSUED 1220 PM EST MON FEB 27 2006 AVIATION... WEAKENING SURFACE TROF SOUTH OF 8 MILE ROAD WILL REDUCE THE SURFACE CONVERGENCE ALONG WITH DEPARTING UPPER JET AND SHRINKING 2-D FGEN FIELDS TO RESULT IN DECREASING SNOW COVERAGE FOR DTW/DET. THEREFORE WE WILL CONTINUE TO SHOW IMPROVEMENTS IN THE TAFS WITH CEILINGS AND VISIBILITIES (MVFR) FOR THE REMAINDER OF THE AFTERNOON HOURS. DRIER AIR UP NORTH AS SEEN IN THE VISIBLE IMAGERY WILL FILTER SOUTH TONIGHT YET UPSTREAM WARM ADVECTION WILL UNFOLD AND SOME MID LEVEL CLOUDS SHOULD MOVE INTO THE STATE THROUGH TUESDAY MORNING WITH LIGHT WINDS AS HIGH SETTLES ACROSS THE GREAT LAKE STATE. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HU LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BGM LONG TERM....KEK YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 PM EST MON FEB 27 2006 .DISCUSSION... MAIN FCST ISSUES ARE LIGHT LES AND TEMPS TONIGHT AND THEN SNOW POTENTIAL WED INTO EARLY THU. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A CONTINUED WRN RIDGE/ERN TROF PATTERN ACROSS THE CONUS. ERN TROF IS BEING ANCHORED BY A POLAR VORTEX IN SE CANADA. VORTEX IN TURN IS BEING LOCKED IN PLACE BY A HUGE BLOCKING HIGH OVER GREENLAND (NEGATIVE NAO). THE VORTEX AND HIGH WILL BE VERY INFLUENTIAL IN THE WEATHER OVER THE UPPER GREAT LAKES OVER THE NEXT 7 DAYS AS BOTH ARE PROGGED TO RETROGRADE THRU THE WEEK. BENIGN NW FLOW IS OCCURRING ACROSS THE UPPER LAKES TODAY BTWN WRN RIDGE AND ERN TROF. AT THE SFC...CENTER OF ARCTIC HIGH PRES WAS CENTERED OVER NE MANITOBA WITH FRONTAL BOUNDARY MARKING SW EXTENT OF ARCTIC AIR EXTENDING FROM MT TO ERN NEBRASKA. A FEW THOUSAND FEET ABOVE THE SFC...RIBBON OF WEAK WAA WITHIN SHARP TEMP GRADIENT ACROSS THE NRN PLAINS (12Z RAOBS SHOW 850MB TEMPS RANGING FROM -17C AT KINL TO 3C/4C AT KBIS/KABR) HAD RESULTED IN A BAND OF MID CLOUDS FROM NE ND ACROSS MOST OF NRN MN INTO WI. MUCH OF THAT CLOUDINESS HAS NOW DISSIPATED. CLOSER TO HOME...LES CONTINUES OFF SUPERIOR AS 850MB TEMPS ARE AROUND -18C. HOWEVER...GENERAL ANTICYCLONIC/DIVERGENT FLOW (CMAN OBS OVER WRN LAKE SUPERIOR SHOW NE WIND WHILE STDM4 IS NNW) IS KEEPING LES ON THE LIGHT SIDE. HOWEVER...ENHANCED CONVERGENCE WAS NOTED OVER THE ERN LAKE AS LAND BREEZE OFF ONTARIO (NE WIND) CONVERGED WITH THE NNW WIND OVER THE CNTRL LAKE. THIS CONVERGENCE ZONE LINGERS AND CONTINUES TO SUPPORT A BAND OF MDT LES FROM JUST E OF STDM4 TO MUNISING. LOW-LEVEL WINDS CHANGE LITTLE TONIGHT FROM WHAT IS BEING OBSERVED CURRENTLY. AXIS OF DIVERGENT FLOW WILL REMAIN BASICALLY WHERE IT IS NOW...ROUGHLY FROM ISLE ROYALE SE ACROSS THE KEWEENAW. THIS WILL ENSURE -SHSN REMAIN LIGHTEST OVER THE WRN FCST AREA...PROBABLY NOTHING MORE THAN FLURRIES. IN FACT...DEVELOPING LAND BREEZE MAY BE SUFFICIENT TO EVENTUALLY KEEP ANY FLURRIES OFFSHORE OF GOGEBIC/ONTONAGON COUNTIES. TO THE E...MODELS TEND TO BREAKDOWN THE CONVERGENCE ZONE OVER ERN LAKE SUPERIOR...BUT IT WOULD SEEM THE OPPOSITE WOULD BE TRUE...CONVERGENCE STRENGTHENING DURING THE NIGHT AS LAND BREEZES STRENGTHEN. THIS WOULD OFFER THE BEST OPPORTUNITY FOR SOME LIGHT ACCUMULATIONS. EVEN IF CONVERGENCE REMAINS...GFS/NAM SHOW INVERSIONS LOWERING FROM AROUND 5KFT NOW TO 3-4KFT DURING THE NIGHT. SO ACCUMULATIONS WILL BE LIMITED. WILL PAINT UP TO 2 INCHES IN ALGER COUNTY TONIGHT...BUT OTHERWISE...EXPECT NOTHING MORE THAN 1 INCH TO THE E OF MARQUETTE. INLAND TEMPS WILL BE TRICKY TONIGHT WITH HUGE BUST POTENTIAL. BAND OF MID CLOUDS MAY REDEVELOP AND OCCASIONALLY BRUSH THE COUNTIES BORDERING WI...BUT FOR THE MOST PART...BELIEVE SKIES WILL BE MOSTLY CLEAR UNDER AXIS OF DIVERGENT LOW-LEVEL LOW. WILL THUS DROP TEMPS WELL BLO GUIDANCE WITH MINS NEAR -18F AT THE LOW END IN THE USUAL COLD SPOTS. ON TUE...LES OVER THE E WILL WIND DOWN TO JUST FLURRIES AS INVERSION DROPS TO AROUND 2.5KFT. DRY AIR AND MODERATING TEMP AT THE BASE OF INVERSION MAY ACTUALLY BRING A COMPLETE END TO EVEN FLURRIES. OTHERWISE...MODELS HAVE BACKED OFF ON GENERATING ANY LIGHT PCPN TUE WITH ONLY THE GFS HINTING AT IT. UPPER JET STREAK WILL DROP ACROSS LAKE SUPERIOR AND LWR MI...PROVIDING UPPER DIVERGENCE IN RIGHT ENTRANCE REGION OF JET. RESULTING ISENTROPIC ASCENT AT THE LOWER LEVELS IS STILL INDICATED BY THE MODELS...BUT WEAKNESS OF LIFT AND DRY LOW-LEVELS THAT MUST BE OVERCOME ARE PROBABLY THE REASON FOR THE DRY SOLUTIONS NOW. WILL DROP PREVIOUS FCST MENTION OF SLIGHT CHC POPS FOR -SN OVER ROUGHLY THE SW HALF OF FCST AREA AND MENTION JUST FLURRIES. WILL THEN LINGER FLURRIES TUE NIGHT AS JET STREAK IS SLOW TO TRANSLATE SE OF THE AREA. NEXT IMPORTANT FCST ISSUE ARISES WED INTO THU. SHORTWAVE MOVING ONSHORE ALONG THE W COAST TUE MORNING WILL LIFT INTO SRN SASKATCHEWAN TUE NIGHT AND WILL THEN BE FORCED ESE WED/THU INTO THE GREAT LAKES DUE TO POLAR VORTEX OVER SE CANADA BEGINNING TO RETROGRADE. COULD BE AN INTERESTING EVENT AS THERE ARE SIMILARITIES TO THE SYSTEM THAT BROUGHT THE BAND OF HEAVY SNOW TO MUCH OF W/CNTRL UPPER MI LAST FRI EVENING. NOT EXPECTING A REPEAT PERFORMANCE YET... BUT THERE IS CERTAINLY THE POTENTIAL TO PRODUCE ADVY TYPE ACCUMULATIONS...ESPECIALLY SINCE 295K SFC (ROUGHLY 700-750MB) SHOWS MIXING RATIOS UPWARDS OF 4G/KG AVBL. ONCE AGAIN...A STRONG BAROCLINIC ZONE WILL BE IN PLACE AS SHORTWAVE PASSES ACROSS THE AREA...AND PCPN WILL BE DEVELOPING ON THE EDGE OF VERY STEEP MIDLEVEL LAPSE RATES ON THE ORDER OF 7-8C/KM. LOW-MIDLEVEL FRONTOGENESIS WILL PLAY A MAJOR ROLE...BUT AT THIS POINT THE GFS DOES NOT SHOW AS STRONG A SIGNAL AS THE NAM. INTERESTING THAT THE NAM IS SHOWING CONSISTENCY WITH THIS SIGNAL EVEN THOUGH ITS STILL BEYOND 48HRS INTO MODEL RUN...AND THE LAST FEW RUNS ARE GENERATING 2/3RDS OF AN INCH OF PCPN. IT IS UNCERTAIN HOW STRONG SHORTWAVE WILL BE...BUT THE SYSTEM WHICH IS OFF THE CA COAST NOW LOOKS IMPRESSIVE. FOR NOW...WILL BRING IN CHC POPS OF SNOW WED...RAISE TO LIKELY WED NIGHT/THU MORNING...THEN LINGER CHC -SHSN THRU THU. FRI-MON...FCST FOR THIS PERIOD WILL LEAN TOWARD THE GFS AS IT HAS TRENDED MORE SO TOWARD WHAT WAS EXPECTED YESTERDAY WHEN THIS TIME FRAME WAS EXAMINED. HUGE BLOCKING MID/UPPER HIGH THAT IS CURRENTLY IN THE VCNTY OF GREENLAND IS STILL TO WEAKEN AND RETROGRADE INTO NCNTRL CANADA BY THE WEEKEND WITH CORRESPONDING POLAR VORTEX OVER SE CANADA ALSO RETROGRADING INTO ONTARIO...BUT ALSO WEAKENING AND ELONGATING W-E OVER SE CANADA. PROVIDED THIS OCCURS...SIGNIFICANT WARMING IS UNLIKELY ACROSS THE UPPER GREAT LAKES AND ANY SHORTWAVES TRACKING ACROSS THE CONUS SHOULD BE SUPPRESSED BY THE PATTERN OVER CNTRL/ERN CANADA. ECMWF WAS PREFERRED YESTERDAY AS IT FOLLOWED THIS THINKING AND HAD STRONG SUPPORT FROM GFS REFORECAST ENSEMBLES. HOWEVER...IT HAS SINCE SHOWN POOR RUN-TO-RUN CONTINUITY FOR LATE IN THE WEEK...AND THE 00Z RUN NOW BRINGS A SFC LOW ACROSS THE PLAINS INTO UPPER MI LATE IN THE WEEKEND. 12Z RUN LOOKS LIKE YESTERDAYS 12Z RUN WITH LOW LIFTING N WELL W OF HERE. THIS SOLUTION IS NOT PREFERRED PROVIDED THE PATTERN OVER CANADA EVOLVES AS DISCUSSED ABOVE. GFS REFORECAST ENSEMBLES LOOK SIMILAR TO YESTERDAYS ENSEMBLES...AND THEY MOST CLOSELY RESEMBLE THE 00Z/12Z GFS SOLUTIONS. 00Z/12Z GFS ALSO HAS SUPPORT FROM THE CANADIAN AND 00Z UKMET TO SOME DEGREE. IN THE WAKE OF THE WED/THU SYSTEM...SFC HIGH PRES RIDGE WILL BUILD SE INTO THE UPPER LAKES FRI/SAT. SHOULD BE COLD ENOUGH FOR LES FRI AND PERHAPS SAT THOUGH IT WILL LIKELY BE LIGHT WITH DRY AIR AND ANTICYCLONIC FLOW DOMINATING. THIS COULD CHANGE IF WEAKENING/ELONGATING POLAR VORTEX DROPS FARTHER S. WITH INCREASING SUN ANGLE...DIURNAL INSTABILITY SHSN WOULD ALSO BECOME WIDESPREAD BOTH AFTERNOONS AS WELL IF TROF/COLD AIR ALOFT DRIFTS FARTHER S. SHORTWAVE EXITING WRN TROF LATE WEEK SHOULD TRACK ACROSS THE PLAINS INTO THE GREAT LAKES LATE IN THE WEEKEND AND EVENTUALLY LEAD TO A DEEPENING TROF OVER THE ERN CONUS BY EARLY NEXT WEEK PER GFS AND REFORECAST ENSEMBLES. WILL CONTINUE WITH A CHC OF SNOW SAT NIGHT/SUN. THERE IS STILL POTENTIAL FOR THIS TO BE A DECENT SNOW EVENT FOR UPPER MI SINCE GULF WILL BE WIDE OPEN. EVEN IF SYSTEM TRACKS TOO FAR S...THE DEEPENING TROF/DEVELOPING CYCLONIC FLOW AND COOLING AT 500MB OVER THE GREAT LAKES WOULD SUPPORT SHSN ACROSS THE FCST AREA...ESPECIALLY THE DAYTIME INSTABILITY TYPE SUN AFTN AND MON AFTN. && .MQT WATCHES/WARNINGS/ADVISORIES... HEAVY FREEZING SPRAY WARNING E 2/3RDS OF LAKE SUPERIOR. && $$ ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1010 AM EST MON FEB 27 2006 .UPDATE... 13Z SURFACE ANALYSIS SHOWED A WARM FRONT EXTENDING E ACROSS THE NRN PLAINS FROM A LOW OVER THE INTERMOUNTAIN W. THIS FRONT WAS LESS PRONOUNCED AS IT EXTENDED FARTHER E OVER LOWER MI DUE TO A WIND COL BETWEEN HIGH PRESSURE CENTERS OVER MANITOBA AND THE SERN USA. JUST N OF THE WARM FRONT...WE WERE ABLE TO INFER AN H8 FGEN AREA OVER MN/WI FROM THE 12Z H8 RAOB STREAMLINE ANALYSIS. THIS IS BEING SUPPORTED BY A BAND OF ENHANCED IR CLOUDS THAT STRETCHES SE FROM ERN WI INTO OH. COLDEST IR TOPS MATCH NICELY WITH THE STRONGEST RETURNS CURRENTLY SEEN ON THE KGRR RADAR. RUC AND FAVORED GFS MODELS SHIFT AN H8-H6 FGEN LAYER EWD WITH SATURATED CONDITIONS UP THROUGH THE -20C LEVEL REMAINING OVER SWRN LOWER MI. THINGS START TO DRY OUT BY EVENING...SO WE EXPECT SNOW TO TAPER BY LATE AFTERNOON. ZONES CURRENTLY HAVE THINGS TAPERING BY AFTERNOON OVER OUR SRN ZONES. WILL MONITOR OVER THE NEXT HOUR AND SEE IF ANOTHER UPDATE IS NEEDED TO EXTEND THE LIKELY SNOW. NO CHANGES ARE ANTICIPATED FOR THE NEARSHORE WATERS FORECAST. WINDS ARE STILL EXPECTED TO VEER TO THE NE AS THE MANITOBA HIGH EXERTS ITS INFLUENCE ON THE AREA. WINDS MAY STRENGTHEN SLIGHTLY BY THIS EVENING...BUT THE OFFSHORE COMPONENT WILL MEAN LITTLE FETCH AND THEREFORE LITTLE WAVE RESPONSE. && .GRR WATCHES/WARNINGS/ADVISORIES...NONE. && $$ TJT mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 935 AM EST MON FEB 27 2006 .SHORT TERM (REST OF TODAY)... LATEST DATA AND TRENDS GENERALLY SUPPORT CURRENT FORECASTS FOR TODAY WITH ONLY MINOR CHANGES EXPECTED IN THE LATE MORNING UPDATE. THOUGH MOISTURE IS STREAMING IN FROM THE NORTHWEST ALOFT...CROSS SECTIONAL ANALYSES AND MODELS SHOW LITTLE...IF ANY...LIFT. THE MOUNTAINS MAY INDUCE OCCASIONAL LEE SIDE STANDING WAVE ALTO CU OR CIRRUS. OTHERWISE MOSTLY SUNNY CONDITIONS SHOULD PREVAIL THROUGH TODAY. MAX TEMPERATURES APPEAR IN LINE APPLYING THE ADIABATIC SCHEME TO OBSERVED DATA AND LATEST RUC OUTPUT. -RFG && .PREVIOUS DISCUSSION... (ISSUED 300 AM EST MON FEB 27 2006) PROBLEM OF THE DAY... FIRE WEATHER PARAMETERS OF SURFACE WIND TO 25 MPH... AND EXPECTED RELATIVE HUMIDITIES TO DIP TO 20 PERCENT THIS AFTERNOON. SEE FIRE WEATHER DISCUSSION BELOW. SYNOPSIS... COLD DRY SURFACE HIGH PRESSURE CENTERED OVER THE TENNESSEE VALLEY THIS MORNING WILL MOVE OVER FLORIDA THIS AFTERNOON. THIS WILL ALLOW A MODERATE WSW FLOW TO DEVELOP OVER NC THIS AFTERNOON. THE DRY AIR MASS WILL MODERATE QUICKLY THIS AFTERNOON. THE MODERATING TEMPS TREND WILL CONTINUE TONIGHT AND TUESDAY AS THE WSW FLOW CONTINUES. THE H5 RIDGE CENTERED OVER THE ROCKIES TODAY WILL EXTEND EASTWARD TO THE APPALACHIANS MUCH OF THIS WEEK... THE RESULTANT WNW FLOW ALOFT WILL ENHANCE THE DRY WARM WEATHER ACROSS CENTRAL NC MID TO LATE WEEK. SHORT TERM (TODAY THROUGH TUESDAY)... THE CURRENT AIR MASS OVER NC IS VERY DRY WITH SURFACE DEW POINTS IN THE 5 BELOW TO 5 ABOVE RANGE. IT TOOK MUCH OF THE EVENING... BUT WINDS FINALLY DECOUPLED ALLOWING TEMPS TO FALL INTO THE 20S BY 200 AM AT ALL REPORTING SITES WITH THE EXCEPTION OF FAY (30). TEMPS BY DAYBREAK WILL FALL TO BETWEEN 20 AND 25. AFTER THE HARD FREEZE THIS MORNING... THE COLD AIR WILL GET PUSHED OUT OF THE REGION ABOUT AS QUICKLY AS IT ARRIVED SATURDAY NIGHT AND EARLY SUNDAY. THE CENTER OF THE SURFACE HIGH WILL REACH FL THIS AFTERNOON ALLOWING A WSW WIND TO GET GOING ACROSS NC. THE VERY DRY AIR MASS WILL MODERATE QUICKLY WITH THE WSW WIND AT 15-20 MPH TODAY. DRY ADIABATIC PARTIAL THICKNESS FORECASTS INDICATES TEMPS 52-57 NE TO SE TODAY. SOME SCATTERED TO THIN BROKEN HIGH CLOUDINESS CAN BE EXPECTED TO ADVECT IN FROM THE NW DURING THE DAY... ESPECIALLY NORTHERN ZONES. FOR TONIGHT AND TUESDAY... THE RAPID MODERATION IN TEMPS WILL CONTINUE ALONG WITH THE WSW LOW LEVEL FLOW. THE WNW FLOW ALOFT FAVORS SOME OCCASIONAL HIGH CLOUDINESS. LOWS TONIGHT MODERATE A GOOD 12-15 DEGREES... AND WILL LIKELY REMAIN ABOVE 32 IN ALL AREAS. THE NAM STATISTICAL GUIDANCE IS FAVORED TUESDAY AS PARTIAL THICKNESS SCHEME INDICATES MID 60S THROUGHOUT THE REGION. WITH LESS WIND... THIS WILL REALLY FEEL MILD. LONG TERM (TUESDAY NIGHT THROUGH SUNDAY)... A WARM DRY PERIOD EXPECTED WED-FRI AS THE UPPER RIDGE ADVANCES FROM THE ROCKIES EAST TO THE APPALACHIANS. THE WARM PERIOD AND DEEP WESTERLY FLOW SHOULD WAX ON WED AND THU AS SURFACE LOW PRESSURE TRACKS FROM THE NORTHERN PLAINS EAST ACROSS NEW ENGLAND. HIGHS SHOULD REACH INTO THE 70S. OVERNIGHT LOWS SHOULD BE IN THE 45 TO 52 RANGE. THESE TEMPS WILL BE 15 TO 20 DEGREES ABOVE NORMAL. THERE CONTINUES TO BE LARGE DIFFERENCES IN MODEL FORECASTS THIS WEEKEND. HPC FAVORS THE EUROPEAN MODEL SOLUTION OF A STORM TRACK FROM THE PLAINS NE THROUGH THE OHIO RIVER VALLEY SAT-SUN. THERE IS SOME POTENTIAL FOR A SECONDARY LOW DEVELOPMENT OVER THE SE STATES. SOME CAD POTENTIAL FOR CENTRAL NC... BUT STILL TOO MUCH DISAGREEMENT IN THE MODELS TO LOWER TEMPS AT THIS POINT. THE CURRENT NEGATIVE PHASE OF THE NAO FAVORS COASTAL DEVELOPMENT. NO CHANGES TO CURRENT FORECAST UNTIL 12Z MODEL RUNS THIS MORNING. AVIATION... VFR CONDITIONS THROUGH PERIOD WITH UNLIMITED VISIBILITIES AND ANY CEILINGS AT OR ABOVE 15000 FEET. ONLY GENERAL AVIATION CONCERN IS GUSTY WEST WINDS AROUND 22 KNOTS BEGINNING A FEW HOURS AFTER SUNRISE TODAY AND PERSISTING INTO EARLY EVENING. FIRE WEATHER... WSW FLOW INCREASES TO 15-20 MPH SUSTAINED WINDS THIS AFTERNOON. GUSTS TO 25 MPH. MINIMUM RH VALUES SHOULD SLIP TO 20 PERCENT. THROUGH COORDINATION WITH THE NORTH CAROLINA FOREST SERVICE AND OTHER SURROUNDING NWS OFFICES... NO RED FLAG WARNINGS WILL BE NECESSARY DUE MAINLY TO THE FINE FUEL MOISTURES REMAINING JUST MOIST ENOUGH. ALSO... TEMPS IN THE 50S OR BELOW DO NOT FAVOR RAPID FIRE GROWTH POTENTIAL. WED-THU WILL HAVE TO BE MONITORED AS THE FUEL MOISTURES WILL REALLY DRY OUT BY THEN... AND SURFACE TEMPS WILL SURGE INTO THE 70S. WINDS MAY NOT REACH RED FLAG CRITERIA OF 25 MPH HOWEVER. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RFG nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OHIO 1020 PM EST MON FEB 27 2006 .SHORT TERM (TONIGHT) RUC AND ETA12 VERIFYING WITH DRY AIR MOVING IN FROM THE NORTH AND WEST AS FCST. SNOW HAS ENDED AT KCLE TO KERI AND WAS ALSO TAPERING FROM THE WEST ACRS THE CNTRL LAKESHORE. THE ONLY AREA OF GOOD RADAR RETURN EXTENDED FROM HURON AND MEDINA COUNTIES INTO STARK AND SRN SUMMIT WITH VSBYS AROUND 1SM IN THE SNOW. XPC THIS TOO WILL TAPER TO FLURRIES BY MIDNIGHT OR SO AFTER WHICH CLOUDS SHOULD BREAK. THERE ARE SOME CLOUDS DEVELOPING OFF OF LAKE HURON IN THE COLD ADVECTION ALTHOUGH THEY DO NOT APPEAR TO BE INCREASING OR ENHANCING AND BUFKIT SHOWS STG AND LOW LVL INVN DVLPG THAT SHOULD NOT ALLOW LAKE EFFECT SNOW SHOWERS TO DVLP LATER TNGT. NO CHG TO FCST LOWS SINCE AS SKIES CLEAR TEMPS SHOULD HAVE NOT PROB DROPPING OFF. && .AVIATION(00Z-24Z)... WIDESPREAD LIGHT TO MODERATE SNOW ACROSS NORTHERN OHIO/NORTHWEST PENNSYLVANIA CONTINUING TO DIMINISH AT THE WESTERN-MOST TERMINALS BUT PERSIST FURTHER SOUTH AND EAST. AS INCREASING SHEAR DEVELOPS IN THE 925-850MB LAYER THIS EVENING AND DRIER AIR WORKS IN FROM THE NORTH...AM EXPECTING CONDITIONS TO IMPROVE AT ALL TERMINALS...EVENTUALLY BECOMING VFR AROUND MIDNIGHT. THE LONE EXCEPTION IS ERIE...WHERE WINDS WILL TAKE ON A HURON FETCH DIRECTION AS THE EVENING PROGRESSES...KEPT CONDITIONS MAINLY IFR ALL THE WAY THROUGH 12Z WHEN INVERSION BEGINS TO COME DOWN UNDER 3000 FT. RUC...WHICH HAS A DECENT HANDLE ON THINGS AT THE MOMENT...ALSO SHOWING INCREASING FRONTOGENESIS IN THIS AREA AS WELL...FURTHER LEADING ME TO BELIEVE SNOW WILL HANG ON AT ERIE THE LONGEST OF ALL TERMINALS. && .PREVIOUS SHORT TERM (TONIGHT THRU WEDNESDAY NIGHT)... LGT SN OR FLURRIES WL TAPER AND END TNGT AS WK UPR ENERGY MOVS SE OF AREA TAKING SEEDER MID LVL CLDS AWAY FM AREA. AREA OF LK ENHANCED SN IN SNOWBELT MAY STILL GET ANOTHER INCH OR SO SO WL LET WRNG/ADVSRY CONT TIL 7 PM. HI PRES RDG OVR AREA LATE TNGT THRU WED MORN SHUD KP MOST OF AREA DRY XCPT FOR PSBL LINGERING LK EFCT SHSN WED MORN FOR SNOWBELT. BUT WITH DRY AIR AND SUBSIDENCE WON'T AMT TO MUCH IF ANYTHING AT ALL SO WL KP ONLY VERY SML CHC. MODELS STILL UNCERTAIN WITH TRACK OF LOW ACRS AREA WED NITE AND THU BUT MODELS NOW COMING ANRD TO MORE OF A CONSENSUS WITH TRACK NR SRN SHORE OF LERI WHICH ALLOWS FOR CD AIR TO STAY IN PLACE LONGER. GFS FASTER WITH LOW AND ASSOCIATED PRECIP AND HAS HAD BETTER HANDLE ON SITUATION ALL ALONG SO WL TEND TO SIDE MORE WITH THE GFS. WL HOLD BACK ENUF TO KP WHOLE AREA DRY TUE NITE AS AREAS OF LGT PRECIP MAY GET CLOSE TO S AND SWRN PART OF CWA. PRECIP SPREADS SW TO NE ACRS AREA WED INTO WED NITE. AMS ALOFT WRMS ENUF TO RA AS PRECIP TYPE BUT ENUF CD AIR MAY STAY TRAPPED IN NERN PART OF AREA FOR FZRA EARLY WED NITE AS SOME EVAP COOLING TAKES PLACE...BUT UNCERTAIN SO TOO EARLY TO DO MUCH WITH THIS YET. BESIDES...PRECIP MAY NOT EVEN BE THAT FAR NE ANYWAY. && .LONG TERM(THU-MONDAY)... PSBLY SOME LEFTOVR RA/SN THU MORN AS LOW EXITS AREA THEN WRAP SCT SHSN INTO FRI BUT MNLY IN NERN HALF WHERE SOME LK ENHANCEMENT SHUD TAKE PLACE. RDGG BLDS IN BY FRI EVE. GUIDANCE POPS LOW. WITH ALL THE UNCERTAINTY WL MNLY CARRY POPS JUST BLW SLGT CHC THRESHOLD FRI AFTN THRU EARLY SUN THEN BRING SML CHC FOR SN LATER SUN THRU MON AS LOW PRES MAY OR MAY NOT BE MOVG THRU OR NR THE AREA. CHGD PRECIP TYPE TO SN DUE TO STRENGTH OF HI OVR SRN CANADA CONTG TO PUSH CD AIR TWD THE AREA. && .CLE WATCHES/WARNINGS/ADVISORIES... .OH...NONE .PA...NONE && $$ SHORT TERM...TK PREVIOUS SHORT TERM...ADAMS LONG TERM...ADAMS AVIATION...LEINS oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 300 AM EST TUE FEB 28 2006 SHORT TERM (TODAY AND TONIGHT)... THE MAIN SHORT TERM FORECAST PROBLEMS ARE DEALING WITH A STALLING COLD FRONT AND THEN LATER TODAY AND TONIGHT...AN INCREASE IN LOW LEVEL GULF MOISTURE. THE COLD FRONT TO OUR IMMEDIATE NORTH WILL LIKELY DROP A LITTLE FURTHER TO THE SOUTH THIS MORNING...AND WILL ESSENTIALLY LIE ALONG AN EAST WEST BOUNDARY FROM EVANSVILLE TO LOUISVILLE TO LEXINGTON. THIS FRONTAL BOUNDARY SHOULD THEN START TO SHIFT NORTHWARD BY OR DURING THE AFTERNOON HOURS. LATER TODAY AND ESPECIALLY TONIGHT...THE RUC...NAM AND GFS ALL INDICATE A PLUME OF GULF RH INTO THE REGION...HOWEVER THE GFS...THE FASTEST OF THE THREE...SEEMS TOO FAST. A FAIRLY DECENT NORTHWEST TO SOUTHEAST TEMPERATURE SPREAD TODAY DUE TO THE PRESENCE OF THE STALLING FRONT ACROSS THE NORTHER PORTIONS OF THE FA...FROM THE MID 50S NORTHEAST TO THE MID 60S SOUTHWEST. --21 (TUESDAY AND WEDNESDAY)... MODELS HAVE BEEN VERY CONSISTENT THRU THE MIDDLE OF THE WEEK...ONLY MINOR TWEAKS TO ONGOING FORECAST. GFS SEEMS TO HAVE BETTER OVERALL LOOK TO THE PATTERN...THOUGH SLIGHTLY LIGHT ON THE MOISTURE IT SEEMS...ESPECIALLY WEDNESDAY AFTERNOON INTO EARLY THURSDAY. HAVE INCREASED CLOUD COVER HERE...AND POPS SOME. ADDED SLIGHT CHANCE FOR THUNDER LATE WEDNESDAY INTO THURSDAY MORNING...WITH MODEST LIS NEARING 0 AS THE FRONT APPROACHES AND PUSHES THROUGH THE FORECAST AREA. USED NAM/GFS MOS BLEND FOR TEMPS...LEX MOS FOR TUESDAY LOOKS WAY TOO LOW FOR TUESDAY HIGHS...AND THE NAM MAYBE OVERDOING THE WARMTH SOME...BLEND LOOKS VERY REASONABLE WHICH GIVES NUMBERS NEAR ENSEMBLE MEANS.--SCHOTT .IN THE EXTENDED (THURSDAY THROUGH MONDAY)... ON THURSDAY THE FRONT WILL DRIFT SOUTH OF THE REGION WITH SFC RIDGING WORKING INTO THE AREA BY FRIDAY...SLIGHTLY ABOVE TO NEAR NORMAL TEMPS EACH DAY...SHOWERS CHANCE THURSDAY THRU THE AFTERNOON WITH A SLIGHT CHANCE OF THUNDER ALONG THE FRONT...DRY FRIDAY. EXTENDED SOLUTIONS HAVE DIVERGED GREATLY STARTING AROUND SATURDAY...WITH THE OPER GFS AN OUTLIER...AS COMPARED TO THE 00Z UKMET/EURO SOLUTIONS. THE GFS IS SLIGHTLY QUICKER IN RETROING THE LARGE ANOMALOUS RIDGE INTO CANADA FROM THE DAVIS STRAIT...WITH THE IMPLICATIONS FOR OUR AREA BEING THAT THE DECAYING POLAR VORT IN QUEBEC WOULD BE NUDGED FUTHER SOUTH...ALTERING THE STORM TRACK FOR THE WEEKEND STORM MORE SOUTH...AND ALSO ALLOW FOR MORE COUPLING WITH THE CANADIAN HIGH TO PULL SOME COOLER AIR INTO THE REGION. THE CANADIAN SHOWS A MORE PROGRESSIVE SOLUTION...ROLLING THE SYSTEM JUST TO THE NORTH FROM IA INTO NORTHERN OH...WITH THE EURO MODELS MUCH FURTHER NORTH AS THEY DO NOT SUPRESS THE POLAR VORT TO THE SOUTH BUT ELONGATE IT ACROSS SOUTH EASTERN CANADA CREATING A MORE ZONAL FLOW ACROSS THE US/CANADIAN BORDER. THE EURO SOLUTIONS AND EVEN THE CANADIAN SOLUTION IS MORE CONSISTENT WITH WHAT THE PRIOR 24 HOURS HAVE SHOWN...HAVE MADE LITTLE IF ANY CHANGES DUE TO THE LAST FEW RUNS OF THE GFS AND THE LOOKS OF SOME OF THE ENSEMBLE MEMBERS. IF THE GFS WERE TO VERIFY THEN TEMPS WOULD BE SLIGHTLY COOLER THAN NORMAL SUNDAY INTO TUESDAY OF NEXT WEEK...IF THE EUROS VERIFIED THEN NORMAL OR WARMER WITH THUNDER STILL POSSIBLE FOR THE WEEKEND. BECAUSE OF THE GFS CHANGES HAVE REMOVED THUNDER WORDING.--SCHOTT && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 330 AM EST TUE FEB 28 2006 .DISCUSSION... PRIMARY CONCERN IS EVOLUTION OF TROUGH ENTERING CNTRL PAC COAST THROUGH THU. UPR TROUGH SLIDING INTO PAC COAST BRINGING PLENTY OF RAIN SHOWERS TO CA WITH RIDGE PRESENT OVR ROCKIES INTO SCNTRL CANADA. SHORTWAVE TROUGH AND WARM AIR ADVECTION SUPPORTING NUMEROUS OBS OF LGT SNOW OVR ALBERTA AND SASKATCHEWAN. LK EFFECT CONTINUES IN NNW FLOW OVR UPR LAKES WITH SUFFICIENT INSTABILITY AND INVERSION HEIGHTS BTWN H9 AND H85. DRY PROFILES ON 00Z CWPL/KINL/KAPX SOUNDINGS LIMITING THE INTENSITY OF THE SNOW SHOWERS. MOST SIG WX HOLDS OFF TIL WED. IN MEANTIME LK EFFECT PERSISTS WITH SUFFICIENTLY COLD AIR AND NW WINDS OVR UPR LAKES ON FLANK OF COLD AIR VORTEX OVR E CANADA/NEW ENGLAND. DRY AIR IN MIXED LAYER AND TYPICAL DAYTIME DIURNAL DISRUPTION SHOULD LIMIT INTENSITY OF SNOW SHOWERS BUT EXPECT SCT-NMRS COVERAGE TODAY OVR E LK SUPERIOR INTO E CWA BTWN MARQUETTE AND NEWBERRY. ONLY OTHER CONCERN IS 130KT H3 JET STREAK LIFTING INTO SCNTRL CANADA/UPR LAKES PLACING UPR MI WITHIN RIGHT REAR QUAD OF THE JET AND UPR DIVERGENCE. OTHERWISE SYNOPTIC SUPPORT FOR ANY PCPN LATE TODAY AND TONIGHT IS MINIMAL. PRIMARY MECHANISM DRIVING THE SNOW UPSTREAM OVR CANADA IS INTENSE WARM AIR ADVECTION WITH H85 TEMPS RANGING FM +9C AT GLASGOW MT TO -16C AT THE PAS IN CNTRL MANITOBA. SUCH INTENSE WARM AIR ADVECTION NEVER MAKES IT AS FAR E AS UPR MI AS UPR LAKES REMAINS IN NW FLOW ON FLANK OF POLAR VORTEX. WEAK WARM ADVECTION BTWN H9-H8 SLIDES INTO FAR W UPR MI LATE TODAY WHICH MAY ALLOW FOR SOME FLURRIES. CHANCE OF FLURRIES LINGERS INTO TONIGHT AS THE WARM AIR ADVECTION COMBINES WITH RRQ JET FORCING. UPSTREAM SOUNDINGS AND MODEL SOUNDINGS INDCIATE DRY AIR PRESENT BTWN THICK MID CLOUD DECK AND SCT LOWER LEVEL CLOUDS SO ANY PCPN SHOULD BE QUITE LIGHT WHEN IT OCCURS. GRADUALLY THIS AREA OF WARM AIR ADVECTION DIMINISHES AS PRIMARY TROUGH SHIFTS INTO N PLAINS AND REFOCUSES AREA OF STRONGEST WARM AIR ADVECTION OVR DAKOTAS/MN. THUS...CHANCES OF PCPN FIRST HALF OF WED OVR UPR MI LOOK LIMITED. BY WED AFTN THE WARM AIR ADVECTION AND INCREASING ISENTROPIC LIFT AND PVA FM SHORTWAVE COMBINE TO INCREASE CHANCES OF PCPN OVR W UPR MI. DIFFERENCES BEGIN TO APPEAR IN TRACK OF MID LEVEL TROUGH AND ASSOCIATED STRIPE OF LOW-MID LEVEL MOISTURE/MID LEVEL FRONTOGENESIS AND BAND OF HEAVIEST QPF. UNFORTUNATELY SOLNS VARY QUITE A BIT WITH GFS/RUC 13KM OVR N CWA INTO LK SUPERIOR AND THE NAM/UKMET AS FAR S AS FAR S CWA. ECMWF SEEMS RIGHT IN THE MIDDLE OF THOSE SETS OF SOLNS. OF NOTE IS THE POLAR VORTEX OVR E CANADA IS CURRENTLY RETROGRADING (MOVING WESTWARD) AND HPC INDICATES TELECONNECTIONS COULD FAVOR EVEN A FARTHER S AXIS WITH VORTEX AXIS THAN MODEL GUIDANCE SHOWS. THIS SEEMS TO FAVOR A FARTHER S TRACK OF THE TROUGH OVR UPR LAKES. THUS...PREFER NAM/UKMET IDEA SHOWING HEAVIEST PCPN OVR S HALF OF CWA WED AFTN INTO WED NIGHT AND HAVE TRENDED THIS WAY IN DEPICTION OF QPF. SOUNDINGS SHOW MAJORITY OF PROFILE WHERE LIFT IS PRESENT IS ABOVE -10C WHICH IS NOT AS FAVORABLE FOR BEST SNOW GROWTH MICROPHYSICS (WOULD PREFER TEMPS FM -12C TO -17C). USED A SNOW-WATER RATIO NEAR CLIMO OF 16:1 AND THIS RESULTED IN 12 HR SNOW AMOUNTS BTWN 4 AND 6 INCHES OVR SW CWA AND 24 HR AMOUNTS OF 4 INCHES OVR KEWEENAW AND E CWA TO NEAR 8 INCHES FOR SW CWA. THESE AMOUNTS ARE CLOSE TO MEETING WARNING CRITERIA. HOWEVER...DID NOT HOIST A WATCH ATTM SINCE THERE IS STILL ENOUGH SOLNS POINTING TOWARD MORE S SOLN AND BEST FORCING AND HEAVIEST SNOW COULD END UP TO THE SW OF CWA. WILL CONTINUE TO MENTION POSSIBILITY OF HEAVY SNOW IN HWO. SYNOPTIC SUPPORT EXITS UPR LAKES THU AM WITH COLD AIR INTRUSION LEADING TO NW LK EFFECT THU NIGHT THROUGH FRI. BUMPED POPS TO LIKELY OVR E CWA NEAR LK SUPERIOR. ALTHOUGH COVERAGE OF SNOW SHOWERS MAY BE HIGH...OVERALL BLYR DRYING AND ANTICYCLONIC LOW LEVEL FLOW SHOULD LIMIT INTENSITY OF SNOW SHOWERS AND ACCUMS. COORD WITH APX AND HPC...THANKS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1200 AM EST TUE FEB 28 2006 .AVIATION... VFR CONDITIONS TO PREVAIL ACROSS THE ENTIRE REGION WITH LIGHT WINDS AS SURFACE HIGH CONTINUES TO BUILD INTO THE REGION. DRY AIR UPSTREAM...BOTH SURFACE AND ALOFT...WILL HELP ERODE PATCHY MVFR CLOUDS NEAR THE OHIO BORDER...WITH UPSTREAM SURFACE DEW POINTS IN THE SINGLE DIGITS. ANTICIPATE ONLY A RETURN OF MID LEVEL CLOUDS TUESDAY AFTERNOON AND EVENING AS WARM AIR ADVECTION KICKS IN. 850 MB TEMPERATURES RISE TO NEAR ZERO BY 00Z...WHICH WILL KEEP LAKE STRATOCU OUT OF THE REGION. BEST 850 MB THETA-E ADVECTION REMAINS OVER THE NORTHERN OHIO VALLEY AS WELL. STRENGTHENING INVERSION WILL ALSO KEEP STRONGER WINDS ALOFT FROM MIXING TO THE SURFACE. && .SHORT TERM...TONIGHT AND TUESDAY THE SNOW FROM THIS MORNING WAS A COMBINATION OF SEVERAL FACTORS THAT INCLUDED A FAVORABLE UPPER JET POSITION (ENTRANCE REGION), 850MB 2-D FRONTOGENESIS, LAKE MICHIGAN CONTRIBUTION AS DELTA T/S WERE A BIT HIGHER THAN PROGGED AND SURFACE CONVERGENCE FROM FAST MOVING SURFACE LOW ACROSS LAKE HURON AND TAILING FRONT SWINGING SOUTH ACROSS THE CWA. IN FACT...IR SATELLITE IMAGERY SUGGESTED A BAROCLINIC LEAF DEVELOPING IN ADVANCE OF SHORT WAVE ACROSS WISCONSIN THIS MORNING THAT QUICKLY MOVED ACROSS OUR REGION LATE THIS MORNING. SO ALL THESE FACTORS ENHANCED OUR SNOWFALL THIS MORNING WITH ABOUT 1 INCH ACROSS THE SOUTHERN 2/3RDS OF THE CWA. THE REMNANTS OF THESE AFOREMENTIONED FEATURES IS STILL OCCURRING SOUTH OF 8-MILE ROAD WITH HINTS OF SOME FGEN SEEN ON THE KGRR 88D. LATEST RUC SUGGESTS THIS WILL QUICKLY DEPART TO OUR SOUTHEAST BEFORE SUNSET AS LOW LEVEL DRY AIR FILTERS SOUTH AS SURFACE HIGH OOZES SOUTHEAST ACROSS THE GREAT LAKES. SO COMBINE THAT WITH LOSS OF DIURNAL COMPONENT...SKY COVER SHOULD GRADUALLY CLEAR OUT AND THIS SHOULD SET UP FOR ALMOST IDEAL RADIATIONAL COOLING OVERNIGHT. WITH UPSTREAM DEWPOINTS INTO THE SINGLE DIGITS...WE WILL UNDERCUT GUIDANCE BY SEVERAL DEGREES WITH SINGLE DIGITS OUTSIDE OF METRO DETROIT. THE SURFACE RIDGE WILL BE OVER THE REGION ON TUESDAY YET UPSTREAM MID LEVEL WARM ADVECTION WILL BE TAKING PLACE. THIS SHOULD RESULT IN AN AC-DECK AS 300MB JET INCREASES DUE TO THE INCREASING THERMAL GRADIENT TO AID IN ADDITIONAL LIFT. THIS IN TURN WOULD HOLD DOWN SURFACE TEMPS SOMEWHAT AS NAMX WOULD SUGGEST AND WE WILL FOLLOW THIS ALONG WITH A BLEND OF THE MAV/MET NUMBERS. && .LONG TERM...TUESDAY NIGHT THROUGH MONDAY THE WEATHER THIS WEEK WILL BE IMPACTED BY WAVES EJECTING OUT OF THE CLOSED LOW OFF THE PACIFIC COAST AND THE INTERACTION WITH UPPER LOW OVER EASTERN CANADA. THE FIRST SUCH WAVE TO WATCH WILL MOVE AROUND THE RIDGE OVER THE WESTERN STATES TUESDAY NIGHT AND WEDNESDAY. THE LATEST MODELS INDICATE THIS WAVE WILL MOVE ACROSS THE GREAT LAKES REGION WEDNESDAY NIGHT...NOT PHASING WITH ANOTHER WAVE MOVING AROUND THE UPPER LOW OVER QUEBEC ON THURSDAY. A LOW PRESSURE SYSTEM WILL DEVELOP AHEAD OF THIS WAVE OVER THE PLAINS AND IS EXPECTED TO TRACK ALONG OR JUST SOUTH OF THE MICHIGAN BORDER WEDNESDAY NIGHT. AS THIS WAVE APPROACHES ON WEDNESDAY...THE BAROCLINIC ZONE WILL LIFT NORTH OVER LOWER MICHIGAN WITH GOOD ISENTROPIC LIFT INTO THE OVERNIGHT HOURS. DESPITE THIS LIFT...FEEL THE GFS IS TOO FAST TO MOISTEN THE LOW LAYERS. THE GFS WHICH SHOWS CONSIDERABLY MORE QPF FOR WEDNESDAY DOES NOT SHOW THE 275K ISENTROPIC SURFACE DROPPING BELOW 15MB DURING THE AFTERNOON. HAVE THEREFORE CONTINUED WITH ONLY CHANCE POPS AND DELAYED THE ONSET OF PRECIP ACROSS THE NORTHERN CWA UNTIL THE AFTERNOON. PRECIP TYPE WILL ALSO BE A CONCERN BOTH WEDNESDAY AND WEDNESDAY NIGHT. HAVE LEFT CHANCE OF FREEZING RAIN AND SNOW IN FOR THE NORTHERN DETROIT SUBURBS AND FURTHER NORTH BOTH WEDNESDAY AND WEDNESDAY NIGHT ALTHOUGH WEDNESDAY NIGHT IS CERTAINLY A GREATER CONCERN. ANY FROZEN PRECIPITATION THAT FALLS WEDNESDAY AFTERNOON IS EXPECTED TO BE BRIEF WITH THE BOUNDARY LAYER WARMING AND CAUSING A CHANGE-OVER TO ALL RAIN IN MOST LOCATIONS BY LATE AFTERNOON. BY WEDNESDAY NIGHT THE GFS IS SLIGHTLY STRONGER THAN MOST OF THE OTHER MODELS WITH THE STRENGTH OF THE UPPER LEVEL WAVE. BECAUSE OF THIS...PREFER TO LEAN TOWARDS THE THERMAL PROFILE OF THE NAM WHICH IS SLOWER FOR COLD AIR ADVECTION TO INCREASE. THIS MEANS THERE MAY BE A GOOD PERIOD OF FREEZING RAIN BEFORE CHANGING BACK OVER TO ALL SNOW. PRECIP WILL LIKELY FALL AS RAIN AS FAR NORTH AS THE I-69 CORRIDOR THROUGH A PORTION OF THE EVENING BEFORE TEMPS START TO FALL MAKING FREEZING RAIN THE CONCERN OVERNIGHT. QPF BETWEEN ONE AND TWO TENTHS OF AN INCH COULD CAUSE SIGNIFICANT ICING OVERNIGHT ON WEDNESDAY. IT LOOKS LIKE THE MAJORITY OF THE FREEZING RAIN WILL BE NORTH OF I-96 BEFORE PRECIP EVENTUALLY CHANGES OVER TO LIGHT SNOW. THIS FAVORABLE AREA FOR FREEZING RAIN IS SUBJECT TO CHANGE AS MODELS CONVERGE ON A SIMILAR THERMAL PROFILE AND TRACK OVER THE NEXT TWO DAYS. BY THIS WEEKEND...MODELS ALL INDICATE THAT THE UPPER LEVEL RIDGE WILL BUILD OVER THE WESTERN GREAT LAKES FRIDAY AND SATURDAY WITH HIGH PRESSURE AT THE SURFACE. WILL CONTINUE WITH DRY FORECAST THROUGH SATURDAY AFTERNOON BUT WILL THEN HAVE TO START WATCHING FOR WARM ADVECTION PRECIP THAT WILL APPROACH FROM THE WEST. ENERGY EJECTING OUR OF THE UPPER LOW OVER THE WEST COAST WILL CAUSE A LOW PRESSURE SYSTEM TO DEVELOP IN THE LEE OF THE ROCKIES. MODELS OFFER A VARIETY OF SOLUTIONS ABOUT THE TRACK OF THIS SYSTEM...RANGING FROM A SOUTHERN TRACK ACROSS KANSAS ON THE 00Z/06Z/27 GFS TO A MORE NORTHERN TRACK ACROSS SOUTH DAKOTA ON THE 00Z/27 ECMWF. THESE VARIATIONS IN TRACK WILL HAVE A SIGNIFICANT IMPACT ON BOTH TEMPERATURES AND PRECIPITATION TYPE FOR LOWER MICHIGAN. 12Z/27 GFS HAS TRENDED TOWARDS THE 00Z/27 ECMWF AND WILL HEDGE FORECAST TOWARDS A BLEND OF THESE TWO MODELS. ALSO PREFER THIS IDEA WITH MODELS SHOWING MORE ENERGY DROPPING DOWN THE BACKSIDE OF THE UPPER LOW ON FRIDAY NIGHT. CHANGES TO THE GOING FORECAST INCLUDED ADDING A CHANCE OF SNOW TO THE TRI CITIES SATURDAY NIGHT AND RAISING TEMPS A COUPLE DEGREES FOR SUNDAY AND MONDAY. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON UNTIL 6 PM TUESDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BGM LONG TERM....KEK AVIATION.....GSS YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OHIO 1159 PM EST MON FEB 27 2006 .AVIATION(06Z-06Z)... LIGHT TO MODERATE SNOW ENDING AT THE MOMENT AT CAK AND YNG...WITH CLEAR SKIES FURTHER WEST. TOL FDY CLE AND MFD SHOULD BE VFR THROUGH THE FORECAST PERIOD AS HIGH PRESSURE SETS UP OVER SOUTHERN ONTARIO. CAK AND YNG WILL BE SOON TO FOLLOW ONCE SNOW/CLOUDS SCOUR OUT...WITH ONLY A BROKEN CLOUD DECK RETURNING BY THE END OF THE PERIOD. INVERSION AT ERIE HAS STEADILY DROPPED ALL EVENING LONG WITH ONLY A FEW CLOUDS STREAMING OFF OF LAKE HURON. WITH LOW DEWPOINTS ADVECTING IN FROM THE NORTH...WILL GO WITH ONLY AN MVFR DECK OVERNIGHT AND REMOVE SNOW FROM FORECAST AT THIS TIME. && .SHORT TERM (TONIGHT) RUC AND ETA12 VERIFYING WITH DRY AIR MOVING IN FROM THE NORTH AND WEST AS FCST. SNOW HAS ENDED AT KCLE TO KERI AND WAS ALSO TAPERING FROM THE WEST ACRS THE CNTRL LAKESHORE. THE ONLY AREA OF GOOD RADAR RETURN EXTENDED FROM HURON AND MEDINA COUNTIES INTO STARK AND SRN SUMMIT WITH VSBYS AROUND 1SM IN THE SNOW. XPC THIS TOO WILL TAPER TO FLURRIES BY MIDNIGHT OR SO AFTER WHICH CLOUDS SHOULD BREAK. THERE ARE SOME CLOUDS DEVELOPING OFF OF LAKE HURON IN THE COLD ADVECTION ALTHOUGH THEY DO NOT APPEAR TO BE INCREASING OR ENHANCING AND BUFKIT SHOWS STG AND LOW LVL INVN DVLPG THAT SHOULD NOT ALLOW LAKE EFFECT SNOW SHOWERS TO DVLP LATER TNGT. NO CHG TO FCST LOWS SINCE AS SKIES CLEAR TEMPS SHOULD HAVE NOT PROB DROPPING OFF. && .PREVIOUS SHORT TERM (TONIGHT THRU WEDNESDAY NIGHT)...LGT SN OR FLURRIES WL TAPER AND END TNGT AS WK UPR ENERGY MOVS SE OF AREA TAKING SEEDER MID LVL CLDS AWAY FM AREA. AREA OF LK ENHANCED SN IN SNOWBELT MAY STILL GET ANOTHER INCH OR SO SO WL LET WRNG/ADVSRY CONT TIL 7 PM. HI PRES RDG OVR AREA LATE TNGT THRU WED MORN SHUD KP MOST OF AREA DRY XCPT FOR PSBL LINGERING LK EFCT SHSN WED MORN FOR SNOWBELT. BUT WITH DRY AIR AND SUBSIDENCE WON'T AMT TO MUCH IF ANYTHING AT ALL SO WL KP ONLY VERY SML CHC. MODELS STILL UNCERTAIN WITH TRACK OF LOW ACRS AREA WED NITE AND THU BUT MODELS NOW COMING ANRD TO MORE OF A CONSENSUS WITH TRACK NR SRN SHORE OF LERI WHICH ALLOWS FOR CD AIR TO STAY IN PLACE LONGER. GFS FASTER WITH LOW AND ASSOCIATED PRECIP AND HAS HAD BETTER HANDLE ON SITUATION ALL ALONG SO WL TEND TO SIDE MORE WITH THE GFS. WL HOLD BACK ENUF TO KP WHOLE AREA DRY TUE NITE AS AREAS OF LGT PRECIP MAY GET CLOSE TO S AND SWRN PART OF CWA. PRECIP SPREADS SW TO NE ACRS AREA WED INTO WED NITE. AMS ALOFT WRMS ENUF TO RA AS PRECIP TYPE BUT ENUF CD AIR MAY STAY TRAPPED IN NERN PART OF AREA FOR FZRA EARLY WED NITE AS SOME EVAP COOLING TAKES PLACE...BUT UNCERTAIN SO TOO EARLY TO DO MUCH WITH THIS YET. BESIDES...PRECIP MAY NOT EVEN BE THAT FAR NE ANYWAY. && .LONG TERM(THU-MONDAY)... PSBLY SOME LEFTOVR RA/SN THU MORN AS LOW EXITS AREA THEN WRAP SCT SHSN INTO FRI BUT MNLY IN NERN HALF WHERE SOME LK ENHANCEMENT SHUD TAKE PLACE. RDGG BLDS IN BY FRI EVE. GUIDANCE POPS LOW. WITH ALL THE UNCERTAINTY WL MNLY CARRY POPS JUST BLW SLGT CHC THRESHOLD FRI AFTN THRU EARLY SUN THEN BRING SML CHC FOR SN LATER SUN THRU MON AS LOW PRES MAY OR MAY NOT BE MOVG THRU OR NR THE AREA. CHGD PRECIP TYPE TO SN DUE TO STRENGTH OF HI OVR SRN CANADA CONTG TO PUSH CD AIR TWD THE AREA. && .CLE WATCHES/WARNINGS/ADVISORIES... .OH...NONE .PA...NONE && $$ SHORT TERM...TK PREVIOUS SHORT TERM...ADAMS LONG TERM...ADAMS AVIATION...LEINS oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1100 AM EST TUE FEB 28 2006 .MORNING UPDATE... UPDATED AFTERNOON FORECAST TO REFLECT TREND TOWARDS MOSTLY SUNNY SKIES THIS AFTERNOON. FORECAST SOUNDINGS SHOW THAT LOW LEVEL MOISTURE WILL NOT ARRIVE UNTIL THE OVERNIGHT PERIOD. EXPECT LIGHT EASTERLY WINDS ACROSS THE NORTH HALF OF OUR CWA FOR THE BULK OF THE AFTERNOON...WITH SOUTHWEST WINDS ACROSS OUR SOUTHERN COUNTIES. STATIONARY FRONT NOW STRETCHES ACROSS NORTHERN KENTUCKY FROM JUST SOUTH OF LOUISVILLE TO NORTH OF JACKSON. COOLER TEMPERATURES WILL CONTINUE JUST NORTH OF THIS FRONT...ALTHOUGH PLENTY OF SUN WILL REDUCE THE BAROCLINICITY ACROSS THIS FRONT BY LATE AFTERNOON. CURRENTLY QUITE A TEMPERATURE GRADIENT EXISTS BETWEEN 35 DEGREES AT COVINGTON TO 50 AT LOUISVILLE. SHORT TERM (TODAY AND TONIGHT)... THE MAIN SHORT TERM FORECAST PROBLEMS ARE DEALING WITH A STALLING COLD FRONT AND THEN LATER TODAY AND TONIGHT...AN INCREASE IN LOW LEVEL GULF MOISTURE. THE COLD FRONT TO OUR IMMEDIATE NORTH WILL LIKELY DROP A LITTLE FURTHER TO THE SOUTH THIS MORNING...AND WILL ESSENTIALLY LIE ALONG AN EAST WEST BOUNDARY FROM EVANSVILLE TO LOUISVILLE TO LEXINGTON. THIS FRONTAL BOUNDARY SHOULD THEN START TO SHIFT NORTHWARD BY OR DURING THE AFTERNOON HOURS. LATER TODAY AND ESPECIALLY TONIGHT...THE RUC...NAM AND GFS ALL INDICATE A PLUME OF GULF RH INTO THE REGION...HOWEVER THE GFS...THE FASTEST OF THE THREE...SEEMS TOO FAST. A FAIRLY DECENT NORTHWEST TO SOUTHEAST TEMPERATURE SPREAD TODAY DUE TO THE PRESENCE OF THE STALLING FRONT ACROSS THE NORTHER PORTIONS OF THE FA...FROM THE MID 50S NORTHEAST TO THE MID 60S SOUTHWEST. --21 (TUESDAY AND WEDNESDAY)... MODELS HAVE BEEN VERY CONSISTENT THRU THE MIDDLE OF THE WEEK...ONLY MINOR TWEAKS TO ONGOING FORECAST. GFS SEEMS TO HAVE BETTER OVERALL LOOK TO THE PATTERN...THOUGH SLIGHTLY LIGHT ON THE MOISTURE IT SEEMS...ESPECIALLY WEDNESDAY AFTERNOON INTO EARLY THURSDAY. HAVE INCREASED CLOUD COVER HERE...AND POPS SOME. ADDED SLIGHT CHANCE FOR THUNDER LATE WEDNESDAY INTO THURSDAY MORNING...WITH MODEST LIS NEARING 0 AS THE FRONT APPROACHES AND PUSHES THROUGH THE FORECAST AREA. USED NAM/GFS MOS BLEND FOR TEMPS...LEX MOS FOR TUESDAY LOOKS WAY TOO LOW FOR TUESDAY HIGHS...AND THE NAM MAYBE OVERDOING THE WARMTH SOME...BLEND LOOKS VERY REASONABLE WHICH GIVES NUMBERS NEAR ENSEMBLE MEANS.--SCHOTT .IN THE EXTENDED (THURSDAY THROUGH MONDAY)... ON THURSDAY THE FRONT WILL DRIFT SOUTH OF THE REGION WITH SFC RIDGING WORKING INTO THE AREA BY FRIDAY...SLIGHTLY ABOVE TO NEAR NORMAL TEMPS EACH DAY...SHOWERS CHANCE THURSDAY THRU THE AFTERNOON WITH A SLIGHT CHANCE OF THUNDER ALONG THE FRONT...DRY FRIDAY. EXTENDED SOLUTIONS HAVE DIVERGED GREATLY STARTING AROUND SATURDAY...WITH THE OPER GFS AN OUTLIER...AS COMPARED TO THE 00Z UKMET/EURO SOLUTIONS. THE GFS IS SLIGHTLY QUICKER IN RETROING THE LARGE ANOMALOUS RIDGE INTO CANADA FROM THE DAVIS STRAIT...WITH THE IMPLICATIONS FOR OUR AREA BEING THAT THE DECAYING POLAR VORT IN QUEBEC WOULD BE NUDGED FUTHER SOUTH...ALTERING THE STORM TRACK FOR THE WEEKEND STORM MORE SOUTH...AND ALSO ALLOW FOR MORE COUPLING WITH THE CANADIAN HIGH TO PULL SOME COOLER AIR INTO THE REGION. THE CANADIAN SHOWS A MORE PROGRESSIVE SOLUTION...ROLLING THE SYSTEM JUST TO THE NORTH FROM IA INTO NORTHERN OH...WITH THE EURO MODELS MUCH FURTHER NORTH AS THEY DO NOT SUPRESS THE POLAR VORT TO THE SOUTH BUT ELONGATE IT ACROSS SOUTH EASTERN CANADA CREATING A MORE ZONAL FLOW ACROSS THE US/CANADIAN BORDER. THE EURO SOLUTIONS AND EVEN THE CANADIAN SOLUTION IS MORE CONSISTENT WITH WHAT THE PRIOR 24 HOURS HAVE SHOWN...HAVE MADE LITTLE IF ANY CHANGES DUE TO THE LAST FEW RUNS OF THE GFS AND THE LOOKS OF SOME OF THE ENSEMBLE MEMBERS. IF THE GFS WERE TO VERIFY THEN TEMPS WOULD BE SLIGHTLY COOLER THAN NORMAL SUNDAY INTO TUESDAY OF NEXT WEEK...IF THE EUROS VERIFIED THEN NORMAL OR WARMER WITH THUNDER STILL POSSIBLE FOR THE WEEKEND. BECAUSE OF THE GFS CHANGES HAVE REMOVED THUNDER WORDING.--SCHOTT && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 956 AM EST TUE FEB 28 2006 .DISCUSSION... UPDATE CONCERNS ARE DIMINISHING LAKE EFFECT AND POSSIBILITIES FOR SNOW LATE THIS AFTERNOON. CURRENT WEATHER...14Z WATER VAPOR LOOP AND 12Z RAOBS SHOWED AN UPPER LEVEL TROUGH COVERING MUCH OF SE CANADA AND AN UPPER RIDGE ACROSS THE CENTRAL PLAINS INTO SOUTH CENTRAL CANADA. UPPER MICHIGAN IS IN NW CONFLUENT FLOW BETWEEN THE TWO FEATURES...MAINTAINING LOW LEVEL HIGH PRESSURE. THIS HIGH PRESSURE AREA STRETCHED FROM NW ONTARIO... ACROSS WESTERN LAKE SUPERIOR AND DOWN INTO SW LOWER MICHIGAN. VERY DRY AIR UNDER THIS HIGH TOO WITH THE 12Z CWPL SOUNDING SHOWING DEWPOINT DEPRESSIONS OF 20-30C FROM 875-500MB. WITH THE NW MID LEVEL FLOW...THIS DRY AIR CONTINUES TO ADVECT INTO UPPER MICHIGAN. AS A RESULT...ALL OF THE LAKE EFFECT CLOUDS HAVE BEEN ERODED OUT OF WESTERN LAKE SUPERIOR. WITH A LONGER FETCH OF NW WINDS ACROSS EASTERN LAKE SUPERIOR ON THE EAST SIDE OF THE HIGH PRESSURE...SOME LAKE EFFECT CLOUDS PERSIST. HOWEVER ALL REFLECTIVITIES HAVE DISSIPATED OFF THE KMQT RADAR FROM THE LAKE EFFECT. 10-20DBZ REFLECTIVITIES ARE OCCURRING OVER NE MINNESOTA INTO WESTERN UPPER MICHIGAN AND NORTHERN WISCONSIN...THOUGH...AND THESE ARE ASSOCIATED WITH A BAND OF MID LEVEL MOISTURE. CLOUD BASES FROM OBSERVATIONS ARE AROUND 10000 FT...AGAIN SHOWING THAT LOW LEVEL DRY AIR EXISTS. 12Z INL SOUNDING SHOWED THAT LOW LEVEL DRY WITH WITH A 25C DEWPOINT DEPRESSION AT 875MB DESPITE BEING SATURATED BETWEEN 650-800MB. THE BAND OF MOISTURE WAS ASSOCIATED WITH AN AREA OF MID-LEVEL FRONTOGENESIS. REST OF TODAY...WITH DIURNAL HEATING AND THE PERSISTENT DRY AIR ADVECTION FROM THE NW...WOULD EXPECT THAT THE LAKE EFFECT OVER EASTERN LAKE SUPERIOR WILL CONTINUE TO DIMINISH. HOWEVER...WITH 850MB TEMPS REMAINING AROUND -16C THROUGH THE AFTERNOON AND THE LONG NW FETCH...MOSTLY CLOUDY SKIES WITH A FEW FLURRIES SHOULD PERSIST...PARTICULARLY OVER LUCE COUNTY. AS FOR THE BAND OF MID CLOUDS...12Z NAM/RUC SEEM TO HAVE A DECENT HANDLE ON THEM...SHOWING THEM MOVING GRADUALLY ENE THROUGH THE DAY. DO NOT BELIEVE THEY WILL MAKE IT TOO FAR EAST DUE TO THE CONFLUENT NW FLOW. NONETHELESS...LOCATIONS ALONG THE WISCONSIN BORDER SHOULD STAY MOSTLY CLOUDY. SNOW CHANCES FROM THE MID CLOUDS SEEM LOW DUE TO THE LOW LEVEL DRY AIR...BUT THERE ARE INDICATIONS OF INCREASED VERTICAL MOTION OVER WESTERN LAKE SUPERIOR AS A RESULT OF A SHRTWV OVER CENTRAL MANITOBA HEADING SE. THEREFORE HAVE MAINTAINED THE SLIGHT CHANCE OF LIGHT SNOW OVER THE WESTERN LAKE...BUT DROPPED THE FLURRIES MENTION IN THE FAR WEST. TEMPERATURES AND WINDS ARE ON TRACK SO NO CHANGES MADE THERE. && .PREV DISCUSSION... PRIMARY CONCERN IS EVOLUTION OF TROUGH ENTERING CNTRL PAC COAST THROUGH THU. UPR TROUGH SLIDING INTO PAC COAST BRINGING PLENTY OF RAIN SHOWERS TO CA WITH RIDGE PRESENT OVR ROCKIES INTO SCNTRL CANADA. SHORTWAVE TROUGH AND WARM AIR ADVECTION SUPPORTING NUMEROUS OBS OF LGT SNOW OVR ALBERTA AND SASKATCHEWAN. LK EFFECT CONTINUES IN NNW FLOW OVR UPR LAKES WITH SUFFICIENT INSTABILITY AND INVERSION HEIGHTS BTWN H9 AND H85. DRY PROFILES ON 00Z CWPL/KINL/KAPX SOUNDINGS LIMITING THE INTENSITY OF THE SNOW SHOWERS. MOST SIG WX HOLDS OFF TIL WED. IN MEANTIME LK EFFECT PERSISTS WITH SUFFICIENTLY COLD AIR AND NW WINDS OVR UPR LAKES ON FLANK OF COLD AIR VORTEX OVR E CANADA/NEW ENGLAND. DRY AIR IN MIXED LAYER AND TYPICAL DAYTIME DIURNAL DISRUPTION SHOULD LIMIT INTENSITY OF SNOW SHOWERS BUT EXPECT SCT-NMRS COVERAGE TODAY OVR E LK SUPERIOR INTO E CWA BTWN MARQUETTE AND NEWBERRY. ONLY OTHER CONCERN IS 130KT H3 JET STREAK LIFTING INTO SCNTRL CANADA/UPR LAKES PLACING UPR MI WITHIN RIGHT REAR QUAD OF THE JET AND UPR DIVERGENCE. OTHERWISE SYNOPTIC SUPPORT FOR ANY PCPN LATE TODAY AND TONIGHT IS MINIMAL. PRIMARY MECHANISM DRIVING THE SNOW UPSTREAM OVR CANADA IS INTENSE WARM AIR ADVECTION WITH H85 TEMPS RANGING FM +9C AT GLASGOW MT TO -16C AT THE PAS IN CNTRL MANITOBA. SUCH INTENSE WARM AIR ADVECTION NEVER MAKES IT AS FAR E AS UPR MI AS UPR LAKES REMAINS IN NW FLOW ON FLANK OF POLAR VORTEX. WEAK WARM ADVECTION BTWN H9-H8 SLIDES INTO FAR W UPR MI LATE TODAY WHICH MAY ALLOW FOR SOME FLURRIES. CHANCE OF FLURRIES LINGERS INTO TONIGHT AS THE WARM AIR ADVECTION COMBINES WITH RRQ JET FORCING. UPSTREAM SOUNDINGS AND MODEL SOUNDINGS INDCIATE DRY AIR PRESENT BTWN THICK MID CLOUD DECK AND SCT LOWER LEVEL CLOUDS SO ANY PCPN SHOULD BE QUITE LIGHT WHEN IT OCCURS. GRADUALLY THIS AREA OF WARM AIR ADVECTION DIMINISHES AS PRIMARY TROUGH SHIFTS INTO N PLAINS AND REFOCUSES AREA OF STRONGEST WARM AIR ADVECTION OVR DAKOTAS/MN. THUS...CHANCES OF PCPN FIRST HALF OF WED OVR UPR MI LOOK LIMITED. BY WED AFTN THE WARM AIR ADVECTION AND INCREASING ISENTROPIC LIFT AND PVA FM SHORTWAVE COMBINE TO INCREASE CHANCES OF PCPN OVR W UPR MI. DIFFERENCES BEGIN TO APPEAR IN TRACK OF MID LEVEL TROUGH AND ASSOCIATED STRIPE OF LOW-MID LEVEL MOISTURE/MID LEVEL FRONTOGENESIS AND BAND OF HEAVIEST QPF. UNFORTUNATELY SOLNS VARY QUITE A BIT WITH GFS/RUC 13KM OVR N CWA INTO LK SUPERIOR AND THE NAM/UKMET AS FAR S AS FAR S CWA. ECMWF SEEMS RIGHT IN THE MIDDLE OF THOSE SETS OF SOLNS. OF NOTE IS THE POLAR VORTEX OVR E CANADA IS CURRENTLY RETROGRADING (MOVING WESTWARD) AND HPC INDICATES TELECONNECTIONS COULD FAVOR EVEN A FARTHER S AXIS WITH VORTEX AXIS THAN MODEL GUIDANCE SHOWS. THIS SEEMS TO FAVOR A FARTHER S TRACK OF THE TROUGH OVR UPR LAKES. THUS...PREFER NAM/UKMET IDEA SHOWING HEAVIEST PCPN OVR S HALF OF CWA WED AFTN INTO WED NIGHT AND HAVE TRENDED THIS WAY IN DEPICTION OF QPF. SOUNDINGS SHOW MAJORITY OF PROFILE WHERE LIFT IS PRESENT IS ABOVE -10C WHICH IS NOT AS FAVORABLE FOR BEST SNOW GROWTH MICROPHYSICS (WOULD PREFER TEMPS FM -12C TO -17C). USED A SNOW-WATER RATIO NEAR CLIMO OF 16:1 AND THIS RESULTED IN 12 HR SNOW AMOUNTS BTWN 4 AND 6 INCHES OVR SW CWA AND 24 HR AMOUNTS OF 4 INCHES OVR KEWEENAW AND E CWA TO NEAR 8 INCHES FOR SW CWA. THESE AMOUNTS ARE CLOSE TO MEETING WARNING CRITERIA. HOWEVER...DID NOT HOIST A WATCH ATTM SINCE THERE IS STILL ENOUGH SOLNS POINTING TOWARD MORE S SOLN AND BEST FORCING AND HEAVIEST SNOW COULD END UP TO THE SW OF CWA. WILL CONTINUE TO MENTION POSSIBILITY OF HEAVY SNOW IN HWO. SYNOPTIC SUPPORT EXITS UPR LAKES THU AM WITH COLD AIR INTRUSION LEADING TO NW LK EFFECT THU NIGHT THROUGH FRI. BUMPED POPS TO LIKELY OVR E CWA NEAR LK SUPERIOR. ALTHOUGH COVERAGE OF SNOW SHOWERS MAY BE HIGH...OVERALL BLYR DRYING AND ANTICYCLONIC LOW LEVEL FLOW SHOULD LIMIT INTENSITY OF SNOW SHOWERS AND ACCUMS. COORD WITH APX AND HPC...THANKS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AJ (SHORT-TERM) JLA (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 606 AM CST TUE FEB 28 2006 .DISCUSSION... FOR THE 00Z SHORT-TERM MDLS (TIL THURS NGT)...LONGWAVE RDG IS EXPCD TO DOMINATE CNTRL NOAM THRU THE PD WITH POLAR VORTS ANCHORED OFF BRITISH COLUMBIA AND OVR ERN QUEBEC. A RDG-RUNNER SHRTWV WL MAINLY PASS TO OUR N ON WED/WED NGT...WITH THE ENERGY THAT ACTUALLY DOES REACH THIS FAR S BEING RATHER SHEARED. AT THE SFC...FNTL BDRY BISECTING THE FA ATTM...JUST A TAD S OF THE I-70 CORRIDOR...WL RMN IN PLACE THRU THIS MRNG BFR BGNG A RETREAT NWD AS A WRMFNT THIS AFTN AS UPSTREAM LO PRES STRENGTHENS AND APPROACHES...WITH WRMFNT SLIDING JUST N OF THE FA BY LATE TNGT/ERY WED MRNG. THE LO PRES WL PASS JUST TO THE N OF THE FA ON WED WITH ASSOCIATED CDFNT REACHING THE NWRN SXNS OF THE FA LATE WED AFTN. CDFNT WL THEN PUSH THRU REMAINDER OF THE FA ON WED EVNG. ANTI-CYC CURVATURE AND HI PRES RDG WL RPDLY BLD IN TO THE AREA ON THURS. MDLS WERE PRETTY SIMILAR ON PROGNOSTIC MASS FIELDS. FOR TDA...FNTL BDRY IMPRESSIVELY HAS COOLED TEMPS ALG/N OF IT INTO THE 20S AND LWR 30S. BUT WITH MUCH OF THE SAME AIRMASS THAT AFFECTED THE FA ON MONDAY JUST S OF THE BDRY...SHD SEE NR PERSISTENCE TEMPS FOR AREAS THAT ARE S OF THE BDRY...AND EXPC THE BDRY TO PUSH N OF THE I-70 CORRIDOR THIS AFTN BUT STILL RMN S OF THE KUIN AREA. MOS TEMPS HV BEEN CONSISTENTLY TOO COOL FOR WRM AIR INTRUSIONS THIS WINTER...AND WL TRY TO BUCK THE TREND BY STICKING WITH PREV FCST. PLENTY OF SUNSHINE SHUD STILL MAKE IT THRU THE THIN CI CLDS...AND PATCHY MID CLDS THAT HV FORMED NOT EXPCD TO LAST LONG INTO THE MRNG HRS. SOME DIURNAL CU CLDS EXPCD TO DVLP IN THE ERN OZARKS AND SRN IL. MDLS ALSO HINT...GFS MORE SO THAN OTRS...OF ST CLDS ALSO SNEAKING NWD LATE THIS PD. DO SEE SOME DVLPG IN ERN TX/WRN LA ATTM...BUT FEEL MUCH OF THIS WL GET SHUNTED OFF TO OUR S AND E THIS PD...IF IT DOES MAKE IT THIS FAR N. FOR WED...IMPRESSIVE MOISTURE RETURN AHD OF CDFNT AND RDG-RUNNER SYS...WITH PWATS RISING TO 300PCT OF NORMAL (~1.1") AND H850 DEWPOINTS TO 8C. INSTABILITY ALSO DECENT...WITH LIFTED INDICES TO -1/-2 AND K INDICES INTO THE MID 20S. HOWEVER...WITH WRM AIR SURGING OVHD FM THE SRN PLNS...THIS SHUD CAP THE AMS TO ANY SFC- BASED CONVECTION...AND LIFTING MECHANISMS NEEDED FOR ELEVATED CONVECTION SEEM TO BE LIMITED TO THE NWRN EDGE OF A LO LVL JET NOSING INTO THE SERN HALF OF THE FA. SOME ADDITIONAL LIFT TO COME FM SRN EDGE OF MID LVL SYS IN THE NRN FA. MDLS SHOW CAP DOES ERODE SOME VERY LATE IN THE AFTN AND EVNG HRS...WITH SOME WDLY SCT CONVECTION PSBL IN THE SERN HALF OF THE FA...BUT LO LVL JET ALSO GETTING PUSHED OFF TO THE E...AND SO WINDOW OF OPPORTUNITY RATHER SML. HV THEREFORE TRIMMED POPS TO 30S IN THE CNTRL/ERN SXNS WHERE BEST MOISTURE/INSTABILITY AXIS WL EXIST AND WL DRIVE ANY CONVECTION THAT DOES DVLP...AND 20S IN THE W. BULK SHEAR DECENT (20 M/S) ALG WITH MID LVL LAPSE RATES TO WHERE SOME STMS...IF ANY DO DVLP...COULD APPROACH SVR LIMITS PROVIDED THEY CAN SUSTAIN THEMSELVES FOR ANY PD OF TIME. ST CLDS IN THE MRNG...AFTER EXPCG TO BE ABLE TO BETTER PUSH NWD INTO THE FA FM THE PREVIOUS NGT...SHUD GET SHUNTED OFF TO THE E BY AFTN ALLOWING SUN TO PUSH TEMPS INTO THE 70S. SOME RECORDS MAY BE THREATENED...SEE BELOW. BY THURS...HI PRES WL DOMINATE THE AREA WITH TEMPS SVRL DEGS COOLER THAN PREVIOUS DAY. FAVORED COOLER MOS TEMPS. TES && .AVIATION... FOR THE 12Z TAFS...IT APRS SWD PROGRESSION OF CDFNT HAS SLOWED OVR W MO...BUT IT MAY BE ANOTHER HR OR TWO BFR IT FINALLY STALLS ALG MS RVR. HV USED RUC FCSTS FOR FNTL PSTN DURG DAY...WHICH WULD SUGGEST DVLPMT OF S WNDS HOLDING OFF KSTL VCNTY TIL ERY AFTN. DONT SEE MUCH IN THE WAY OF CLDNS TDA OTHER THAN CI...BUT HV ADDED SM LGT FOG/HZ FOR A FEW HRS ARND SNRS FOR KUIN AND KSTL VCNTY TAFS. VFR CONDS SHUD CONT INTO THIS EVE...BUT RH CROSS SECTIONS AND FCST SNDGS INDICATE ST FORMING/ADV INTO AREA AFT 06Z. PATCHES OF BLACK ST ON THE 11-3.9 STLT IMAGERY WHICH HV FORMED OVR TX DURING THE PAST FEW HRS CERTAINLY GIVES THIS SM CREDENCE...SO HV INTRODUCED THE LEADING EDGE OF THESE LWR CLDS TWD THE END OF THE FCST PD. TRUETT && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 1012 AM EST TUE FEB 28 2006 .SHORT TERM UPDATE...CONSIDERABLE HIGH CLDS ACROSS THE REGION THIS MORN. SRT RANGE MDLS ALL SIMILAR IN SHOWING THIS HIGH LVL MOISTURE MOVING E AND OFFSHR THIS AFTN. WILL LIKELY WORD MCDY BECOMING PC FOR THIS AFTN. DESPITE CLDS TEMPS ARE WARMING THRU THE 50S MOST SPOTS AND WITH SOME SUN THIS AFTN SHLD REACH LOW/MID 60S INLAND. NE CST WILL LIKELY BE COOLER AS WEAK BNDRY IS IN VCNTY AND AND ONSHR WIND WILL REALLY COOL TEMPS...THIS IS ALREADY COVERED PRETTY WELL IN CRNT GRIDS. && .AVIATION...MOSTLY HIGH CLOUDS WITH A LITTLE MID DECK THROWN IN THROUGH THE PERIOD. WEST TO SOUTHWEST SURFACE WINDS NO HIGHER THAN AROUND 15 KT THIS AFTERNOON. && .MARINE...EAST-WEST STATIONARY BOUNDARY JUST TO THE NORTH APPEARS TO HAVE DIPPED INTO THE NORTHERN COASTAL WATERS NORTH OF ABOUT MANTEO. WINDS AT DUCK HAVE COME AROUND TO DUE NORTH AND WAVES ARE DOWN TO 1-2 FEET. DID SOME REARRANGING OF THE COASTAL ZONES TO SPLIT OFF THE ZONE NORTH OF OREGON INLET. WENT WITH RUC SOLUTION THROUGH THIS EVENING...WHICH HAS THE BACKING OF THE 06Z ETA12 AND ETA80 AND TO A LESSER EXTENT THE 06Z GFS. AS SEAS HAVE COME DOWN NORTH OF OREGON I HAVE TAKEN DOWN THE SMALL CRAFT FOR THAT ZONE BUT HAVE CONTINUED IT FOR THE REMAINDER OF THE COASTAL WATERS. IN ADDITION I DID SOME REWORDING FOR THE ALBEMARLE SOUND AS WELL...SAME SPEEDS BUT HAD TO TWEAK WIND DIRECTION. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY FOR AMZ152-154-156-158 UNTIL 4 PM TUESDAY. && $$ RF/HSA nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1051 AM CST TUE FEB 28 2006 .UPDATE... MINOR ADJUSTMENTS WERE MADE TO DEWPOINTS/TEMPS/WINDS BASED ON CURRENT OBSERVATIONS. THE RUC APPEARS TO HAVE A BETTER HANDLE ON SURFACE MOISTURE THROUGH THIS AFTERNOON...WHICH WILL YIELD LOWER RELATIVE HUMIDITY FORECAST FOR WESTERN OKLAHOMA AND WESTERN NORTH TEXAS. THE LOWEST HUMIDITIES ARE STILL EXPECTED OVER FAR NORTHWEST AND WEST-CENTRAL OKLAHOMA. THANKFULLY...WINDS SHOULD BEHAVE THIS AFTERNOON ALTHOUGH THEY WILL BEGIN TO PICK UP AS LEE TROUGH INTENSIFIES. COULD SEE SOME GUSTS OVER 20 MPH MID-LATE AFTERNOON...BUT SUSTAINED SPEEDS ARE STILL EXPECTED TO REMAIN IN THE 10 TO 20 MPH RANGE. WINDS WILL BE STRONGEST ACROSS AND SOUTHEAST OF INTERSTATE 44 CORRIDOR. TOMORROW WILL BE A DIFFERENT STORY...AS WARM TEMPS AND STRONG WINDS WILL LIKELY LEAD TO A RED FLAG DAY OVER A LARGER AREA. MORE ON THIS LATER THIS AFTERNOON. && .PREV DISCUSSION... (ISSUED 406 AM CST TUE FEB 28 2006) DISCUSSION... A VERY WARM DAY EXPECTED TODAY WITH TEMPERATURES CLIMBING INTO THE 80S IN MOST LOCATIONS. WITH THE WARM TEMPERATURES...FIRE WEATHER WILL BE A CONCERN TODAY ESPECIALLY IN THE WEST WHERE RH WILL DIP TO LESS THAN 20 PERCENT. WINDS WILL BE LESS THAN YESTERDAY AND THE DRY AIR IN THE TEXAS PANHANDLE WILL LIKELY NOT WORK TOO FAR EAST INTO THE AREA TODAY... BOTH OF WHICH WILL HELP A LITTLE. BUT RED FLAG WARNING IS NEEDED FOR TEMPERATURES AND HUMIDITY IN THE WESTERN TWO TIERS OF COUNTIES. TEMPERATURES IN SOME AREAS WILL APPROACH RECORDS /WHICH INCLUDE 85 IN SPS.. 84 IN GAGE.. 80 IN PNC.. 83 IN HBR/ BUT OKC RECORD LOOKS SAFE THANKS TO A 90 DEGREE RECORD FROM 1904. MODELS STILL SEEM TO BE HAVING A TOUGH TIME WITH LOW LEVEL MOISTURE PROGS AS BOTH GFS AND NAM ARE BRINGING SURFACE DEWPOINTS IN THE LOWER 60S IN SOUTHEAST OKLAHOMA THIS AFTERNOON. HAVE GONE MUCH LOWER IN THE GRIDS. ANOTHER WARM DAY TOMORROW AND THIS TIME WINDS WILL BE STRONGER AND DRY LOW LEVEL AIR WILL MOVE FARTHER EAST. FIRE WEATHER WATCH IS BEING ISSUED FOR THE ENTIRE AREA FOR TOMORROW WITH THE GREATEST CONCERN IN THE SOUTHWEST. COLD FRONT IS EXPECTED TO MOVE INTO NORTHWEST OKLAHOMA TOMORROW MORNING AND LIKELY BE JUST SOUTH OF OKC AND LAW BY 00Z. THERE IS A CHANCE OF PRECIPITATION NORTH OF THE FRONT PERHAPS AS EARLY AS WEDNESDAY NIGHT BUT MORE LIKELY BEGINNING ON THURSDAY. GFS IS A LOT FARTHER NORTH WITH THE DEVELOPING PRECIPITATION. ONE CONTRIBUTING FACTOR TO THAT MAY BE THAT THE GFS KEEPS A LOT MORE LOW LEVEL MOISTURE NORTH OF THE FRONT. THE 00Z GFS WAS 10 DEGREES CELSIUS HIGHER WITH THE 850 MB DEWPOINT THAN THE NAM. AT THIS POINT WILL KEEP THE PRECIPITATION CHANCES FARTHER SOUTH CLOSER TO THE SURFACE BOUNDARY. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 80 52 83 46 / 0 0 0 10 HOBART OK 83 50 84 46 / 0 0 0 10 WICHITA FALLS TX 83 52 86 51 / 0 0 10 20 GAGE OK 85 47 79 39 / 0 0 0 10 PONCA CITY OK 81 51 78 42 / 0 0 0 10 DURANT OK 79 55 84 54 / 0 0 10 20 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR OKZ004-OKZ005-OKZ006-OKZ007-OKZ008-OKZ009- OKZ010-OKZ011-OKZ012-OKZ013-OKZ014-OKZ015-OKZ016-OKZ017- OKZ018-OKZ019-OKZ020-OKZ021-OKZ022-OKZ023-OKZ024-OKZ025- OKZ026-OKZ027-OKZ028-OKZ029-OKZ030-OKZ031-OKZ032-OKZ033- OKZ034-OKZ035-OKZ036-OKZ037-OKZ038-OKZ039-OKZ040-OKZ041- OKZ042-OKZ043-OKZ044-OKZ045-OKZ046-OKZ047-OKZ048-OKZ050- OKZ051-OKZ052. RED FLAG WARNING UNTIL 7 PM CST THIS EVENING FOR OKZ004-OKZ005- OKZ009-OKZ010-OKZ011-OKZ014-OKZ015-OKZ016-OKZ021-OKZ022- OKZ033-OKZ034-OKZ035-OKZ036. TX...FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY AFTERNOON FOR TXZ083-TXZ084-TXZ085-TXZ086-TXZ087-TXZ088- TXZ089-TXZ090. RED FLAG WARNING UNTIL 7 PM CST THIS EVENING FOR TXZ083-TXZ084- TXZ085-TXZ087-TXZ088. && $$ 11/20 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 300 AM CST TUE FEB 28 2006 .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT MODELS DOING PRETTY GOOD IN THE NEAR TERM. TWO CONCERNS FOR THIS PERIOD BOTH INVOLVE PRECIPITATION CHANCES AND TYPE FOR TONIGHT AND AGAIN AT THE END OF THE PERIOD FRIDAY NIGHT. LATEST SURFACE ANALYSIS CLEARLY SHOWS STATIONARY FRONT ACROSS SOUTHWEST PART OF THIS FORECAST AREA. KPHP TEMPERATURE AT 20Z IS 75F WHILE KPIR IS 51F. RUC SOUNDINGS SHOW H85 TEMPERATURES OVER KABR AROUND +13C. HOWEVER TEMPERATURES IN THE NORTHEAST PART OF THIS AREA ARE BELOW 0C AT THE SURFACE. ANY PRECIPITATION FALLING IN THIS AREA COULD WELL BE FREEZING PRECIPITATION. H5 PATTERN CONTINUES A WEST COAST TROUGH WITH A MIDWEST RIDGE. THERE IS ALSO AN UPPER WAVE THAT APPROACHES THE REGION TONIGHT ACROSS THE TOP OF THE WAVE. IT LOOKS INCREASINGLY LIKELY THAT THE MAJORITY OF ANY PRECIPITATION WILL FALL NORTH OF THIS AREA. HOWEVER DID COVER THE NORTHERN TIER OF COUNTIES AS WELL AS THE FAR EAST PART OF MY AREA WITH SLIGHT CHANCE CATEGORY AREAS OF FREEZING RAIN OR SNOW. TOMORROW IT WILL CHANGE TO RAIN OR FREEZING RAIN. DID CONTEMPLATE PULLING THIS AREA OUT BUT IF THE SURFACE LOW AND INVERTED TROUGH WERE JUST SLIGHTLY FARTHER WEST THAN PROGGED IT WOULD HAPPEN. SO FINALLY DECIDED TO LEAVE IT. AS THE WAVE MOVES PAST COLD AIR IS DRAGGED ACROSS THE AREA TOMORROW AFTERNOON. H85 TEMPS DROP TO -18C BY 18Z THURSDAY. BY FRIDAY THIS AGAIN REVERSES AND WARM ADVECTION PUSHES IN AS RIDGE REBUILDS OVER AREA. BY FRIDAY NIGHT HAVE BROUGHT A CHANCE OF SNOW INTO THE EAST AS STRONG WARM ADVECTION OVERRUNS COLD AIR LEFT IN THIS AREA. .LONG TERM...SATURDAY THROUGH TUESDAY REFINEMENT IN EXTENDED RANGE MODELS CONTINUES... DAY 4 SHOULD INCLUDE A PRECIP EVENT IN PROGRESS. THERMAL PROFILE FROM SURFACE UP TO PRECIPITATION FORMATION REGION NOW BEGINNING TO TREND SO WARM...WITH STRONG LOW/MID LEVEL WARM AIR ADVECTION...THAT A SNOW FORECAST BECOMING INCREASING DIFFICULT TO JUSTIFY/IMAGINE. RATHER...NOW APPEARS TO BE MORE OF A RAIN AND/OR FREEZING RAIN EVENT TO START...AND MAY EVENTUALLY CHANGE OVER TO SNOW IF ENOUGH LOW LEVEL COLD AIR IS INTRODUCED INTO THE SYSTEM. THE CULPRIT FOR PRECIPITATION POTENTIAL IS AN UPPER LOW FORECAST TO LIFT OUT OF THE EASTERN PACIFIC OCEAN AND TRACK NORTHEASTWARD ACROSS THE DAKOTAS...BEFORE TURNING AND DIVING SOUTHEASTWARD ACROSS THE MISSISSIPPI RIVER VALLEY. POTENTIAL FOR PRECIPITATION PERSISTS THROUGH SATURDAY NIGHT AND SUNDAY...BEFORE THINGS QUIET DOWN SUNDAY NIGHT. HOWEVER...MOST LIKELY TO SEE AN AREA OF STRATUS DEVELOP AND REMAIN ACROSS EASTERN HALF OF CWA THROUGH MONDAY...BEFORE HIGH PRESSURE PUSHES CLOUDS SOUTH AND EAST OUT OF THIS AREA. THERE COULD BE SOME SIGNIFICANT MEASURABLE AMOUNTS IN EXCESS OF 0.50 INCH WATER EQUIVALENT...EITHER IN THE FORM OF FREEZING RAIN OR SNOW. THIS SYSTEM WILL CONTINUE TO NEED TO BE CLOSELY MONITORED. TEMPERATURES CONTINUE TO BE OF A CONSERVATIVE NATURE...KEEPING LOWS MAINLY IN THE TEENS AND 20S SATURDAY NIGHT...WITH HIGHS SATURDAY AND SUNDAY IN THE 20S TO MID 30S. SEE 925HPA THERMAL PROGS FOR THE DETAILS. BY MONDAY...WESTERN CWA SHOULD BE IN A WARM AIR ADVECTION PATTERN WITH MORE SUN THAN CLOUDS OVER THAT AREA...SO CONTINUED WARMER FORECAST TEMPS THERE MONDAY AND TUESDAY...WITH SHALLOW COLD AIR EXPECTED TO STAY PUT ACROSS EASTERN CWA. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ KEEFE/DORN sd