Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 01/12/07

UPDATE...MID MRNG UPDATE ONLY INVOLVED THE END OF THE SNOW ADVSRY FOR THE FAR WRN ZNS. CAMERAS IN FAR WRN MD/ERN WV SHOW IMPRVG CONDITIONS.

WOODY!

****

SHORT TERM (TODAY AND TONIGHT)... WATER VAPOR LOOP SHOWS A LONG WAVE TROUGH MOVING EAST OF THE REGION...WITH A RIDGE ACROSS THE ROCKIES. ACARS 400-250MB WIND OBSERVATIONS REVEAL A NORTHWEST JET OF 140-170KT FEEDING INTO THE BASE OF THE TROUGH FROM SOUTH CENTRAL CANADA THROUGH THE MID ATLANTIC. 04Z SURFACE ANALYSIS PLACED A TROUGH IN THE LEE OF THE APPALACHIANS...WITH A 1032MB ANTICYCLONE ACROSS THE SOUTH CENTRAL CONUS. SEVERAL NEARLY STATIONARY WEST-EAST BOUNDARIES WERE DRAPED ACROSS SOUTH CENTRAL CANADA AND UPPER MIDWEST.

WHILE 03Z SHORT RANGE ENSEMBLES AND 00Z NAM INDICATE ADDITIONAL SNOW WATER EQUIVALENT OF A TENTH OF AN INCH ACROSS THE MOUNTAINS EARLY THIS MORNING...NATIONAL RADAR LOOP SHOWS STREAMERS STILL COMING OFF THE GREAT LAKES. HAVE THEREFORE EXTENDED THE SNOW ADVISORY UNTIL 10:00 AM FOR AN ADDITIONAL 1-2" OF SNOW IN THE FAVORED UPSLOPE LOCATIONS. WITH ANTICYCLONIC FLOW SUPPORTED BY RIDGE BUILDING IN THIS AFTERNOON...WARM ADVECTION AND LOW LEVEL SHEAR WILL DIMINISH REMAINING SNOW SHOWERS AND MUCH OF THE UPSLOPE CLOUDINESS.

EAST OF THE MOUNTAINS...STEEP LOW LEVEL LAPSE RATES ARE SUPPORTING ISOLATED FLURRIES EARLY THIS MORNING. THESE FLURRIES WILL DIMINISH SHORTLY AFTER SUNRISE AS UPSLOPE SNOW SHOWERS BECOME LESS NUMEROUS AND EFFICIENT. CLOUDS WILL BE BREAKING EARLY THIS MORNING...WITH SOME REDEVELOPMENT OF CUMULUS DURING THE LATE MORNING. WITH STRONG COLD ADVECTION...WENT BELOW MOS FOR HIGH TEMPERATURES.

SKY WILL BECOME CLEAR ACROSS THE REGION BY LATE EVENING AS HIGH PRESSURE SURFACE AND ALOFT SETTLES INTO THE MID ATLANTIC. LOOSENING GRADIENT WILL ALLOW WINDS TO DECOUPLE...AND WITH DRY AIRMASS WILL SEE GREAT RADIATIONAL COOLING. ANTICIPATE SINGLE DIGITS IN FAR WESTERN VALLEYS...MID TEENS RURAL AREAS...LOW TO MID 20S ACROSS THE CITIES AND UPPER TEENS ABOVE 2500FT.

AVIATION... GRADIENT WILL SUPPORT NW WIND GUSTS TO 25KTS TODAY.

MARINE... WILL HAVE WINDS OF 20-25KT IN THE FORECAST TODAY...WITH THE SMALL CRAFT ADVISORY CONTINUING UNTIL EARLY EVENING.

PARTIAL DOWNSLOPE THU NIGHT INTO FRI AND A DECENT PRES GRAD BEHIND THE DEPARTING HIGH PRES. CONCERNED ABOUT POSSIBLE SCA WINDS DEVELOPING BUT FOR NOW NOT HIGH ENOUGH CONFIDENCE AND NOT ANY PERSUASIVE MODEL WIND DATA ATTM TO MENTION IN THE FCST...WILL JUST NEED TO KEEP AN EYE ON LATER RUNS.

GRAD TIGHTENS AGAIN AROUND SUNDAY BETWEEN OH VLY LOW AND ATLC HIGH AND GOOD SW WINDS...WITH ANOTHER POSSIBLE SCA HEADLINE.

LONG TERM...THURSDAY THROUGH TUESDAY...

THU-FRI HIGH PRES WILL MOVE OFFSHORE AND ALLOW WARM SW FLOW TO DEVELOP ACROSS THE MID ATLANTIC. 850 WINDS WILL INCREASE TO NEAR 50 KT ON SUN AS A WARM FRONT MOVES NORTH OF THE REGION ASSOCIATED WITH THE DEEPENING LOW OVER THE LOWER OHIO VALLEY. STILL MOISTURE TRANSPORT OVER THE VIRGINIAS IS PRETTY POOR AND DON`T SEE MUCH IN THE WAY OF PRECIPITATION FOR THE STERLING CWFA IN THIS WARM SECTOR...TIL THE STRONG COLD FRONT APPROACHES SUN NIGHT. BETTER CHANCES ON MONDAY AS FRONT DEVELOPS AN IMPRESSIVE POOL OF LIFT ACROSS MD/VA. WITH SOME RUN-RUN CONSISTENCY IN MONDAY PRECIP CHANCES HAVE INCREASED POPS TO BETWEEN 40 TO 50 ACROSS THE CWFA. COLDER AIR WILL FILTER IN MONDAY NIGHT AND ESPECIALLY TUESDAY...WILL CONTINUE TO INDICATE SNOW MIXING IN DURING THE TAIL OF THE PRECIP MONDAY NIGHT WITH SOME UPSLOPE SNOW SHOWERS POSSIBLE ALONG THE ALLEGHENY FRONT ON TUESDAY. HAVE BACKED OFF THE POPS PREVIOUSLY INDICATED TUE AND TUE NIGHT EAST OF THE RIDGE WHERE MOISTURE WILL PROBABLY BE LACKING.

TEMPS WILL BE WELL ABOVE NORMAL FRI THROUGH MON IN SOUTHWESTERLY FLOW. 00Z GFS AND ESPECIALLY THE LATEST ECMWF CONTINUE TO SHOW A NICE CHUNK OF ARCTIC AIR DROPPING INTO THE MIDWEST WITH THIS SYSTEM MON-TUE...BUT STILL NOT CONVINCED AIRMASS WILL REMAIN INTACT OR FOR THAT MATTER MAKE IT TO THE MID ATLANTIC TO BRING US SOME MORE REALISTIC MID-WINTER CONDITIONS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR ANZ530>537.

&&

$$

.UPDATE...DID AN ERLY MRNG UPDT OF ZNS/EOL TO REMOVE MENTION OF FLURRIES IN METRO AREAS. SNOW ADVSRY FAR W REMAINS IN EFFECT.

WOODY! ****

.SHORT TERM (TODAY AND TONIGHT)... WATER VAPOR LOOP SHOWS A LONG WAVE TROUGH MOVING EAST OF THE REGION...WITH A RIDGE ACROSS THE ROCKIES. ACARS 400-250MB WIND OBSERVATIONS REVEAL A NORTHWEST JET OF 140-170KT FEEDING INTO THE BASE OF THE TROUGH FROM SOUTH CENTRAL CANADA THROUGH THE MID ATLANTIC. 04Z SURFACE ANALYSIS PLACED A TROUGH IN THE LEE OF THE APPALACHIANS...WITH A 1032MB ANTICYCLONE ACROSS THE SOUTH CENTRAL CONUS. SEVERAL NEARLY STATIONARY WEST-EAST BOUNDARIES WERE DRAPED ACROSS SOUTH CENTRAL CANADA AND UPPER MIDWEST.

WHILE 03Z SHORT RANGE ENSEMBLES AND 00Z NAM INDICATE ADDITIONAL SNOW WATER EQUIVALENT OF A TENTH OF AN INCH ACROSS THE MOUNTAINS EARLY THIS MORNING...NATIONAL RADAR LOOP SHOWS STREAMERS STILL COMING OFF THE GREAT LAKES. HAVE THEREFORE EXTENDED THE SNOW ADVISORY UNTIL 10:00 AM FOR AN ADDITIONAL 1-2" OF SNOW IN THE FAVORED UPSLOPE LOCATIONS. WITH ANTICYCLONIC FLOW SUPPORTED BY RIDGE BUILDING IN THIS AFTERNOON...WARM ADVECTION AND LOW LEVEL SHEAR WILL DIMINISH REMAINING SNOW SHOWERS AND MUCH OF THE UPSLOPE CLOUDINESS.

EAST OF THE MOUNTAINS...STEEP LOW LEVEL LAPSE RATES ARE SUPPORTING ISOLATED FLURRIES EARLY THIS MORNING. THESE FLURRIES WILL DIMINISH SHORTLY AFTER SUNRISE AS UPSLOPE SNOW SHOWERS BECOME LESS NUMEROUS AND EFFICIENT. CLOUDS WILL BE BREAKING EARLY THIS MORNING...WITH SOME REDEVELOPMENT OF CUMULUS DURING THE LATE MORNING. WITH STRONG COLD ADVECTION...WENT BELOW MOS FOR HIGH TEMPERATURES.

SKY WILL BECOME CLEAR ACROSS THE REGION BY LATE EVENING AS HIGH PRESSURE SURFACE AND ALOFT SETTLES INTO THE MID ATLANTIC. LOOSENING GRADIENT WILL ALLOW WINDS TO DECOUPLE...AND WITH DRY AIRMASS WILL SEE GREAT RADIATIONAL COOLING. ANTICIPATE SINGLE DIGITS IN FAR WESTERN VALLEYS...MID TEENS RURAL AREAS...LOW TO MID 20S ACROSS THE CITIES AND UPPER TEENS ABOVE 2500FT.

&&

.AVIATION... GRADIENT WILL SUPPORT NW WIND GUSTS TO 25KTS TODAY...WITH ISOLATED FLURRIES POSSIBLE FROM STRATOCU DECK NORTH OF KCHO EARLY THIS MORNING (NO REDUCTION OF CEILINGS OR VISIBILITIES ARE ANTICIPATED). BUILDING RIDGE WILL ALLOW CLOUDS TO DIMINISH AS WINDS DECOUPLE THIS EVENING.

&&

.MARINE... 00Z GFS/ETA MOS AT THOMAS POINT BOTH SUGGEST SUSTAINED WINDS WILL BE IN THE 19-22KT RANGE TODAY...AND AROUND 10KT RANGE TONIGHT. 00Z NAM/GFS PROXIMITY LAND BUFKIT FORECAST SOUNDINGS SUGGEST ADDITIONAL WIND GUST MOMENTUM OF 24-28KT. WILL HAVE WINDS OF 20-25KT IN THE FORECAST TODAY...WITH THE SMALL CRAFT ADVISORY CONTINUING UNTIL EARLY EVENING.

PARTIAL DOWNSLOPE THU NIGHT INTO FRI AND A DECENT PRES GRAD BEHIND THE DEPARTING HIGH PRES. CONCERNED ABOUT POSSIBLE SCA WINDS DEVELOPING BUT FOR NOW NOT HIGH ENOUGH CONFIDENCE AND NOT ANY PERSUASIVE MODEL WIND DATA ATTM TO MENTION IN THE FCST...WILL JUST NEED TO KEEP AN EYE ON LATER RUNS.

GRAD TIGHTENS AGAIN AROUND SUNDAY BETWEEN OH VLY LOW AND ATLC HIGH AND GOOD SW WINDS...WITH ANOTHER POSSIBLE SCA HEADLINE.

&&

.LONG TERM...THURSDAY THROUGH TUESDAY...

THU-FRI HIGH PRES WILL MOVE OFFSHORE AND ALLOW WARM SW FLOW TO DEVELOP ACROSS THE MID ATLANTIC. 850 WINDS WILL INCREASE TO NEAR 50 KT ON SUN AS A WARM FRONT MOVES NORTH OF THE REGION ASSOCIATED WITH THE DEEPENING LOW OVER THE LOWER OHIO VALLEY. STILL MOISTURE TRANSPORT OVER THE VIRGINIAS IS PRETTY POOR AND DON`T SEE MUCH IN THE WAY OF PRECIPITATION FOR THE STERLING CWFA IN THIS WARM SECTOR...TIL THE STRONG COLD FRONT APPROACHES SUN NIGHT. BETTER CHANCES ON MONDAY AS FRONT DEVELOPS AN IMPRESSIVE POOL OF LIFT ACROSS MD/VA. WITH SOME RUN-RUN CONSISTENCY IN MONDAY PRECIP CHANCES HAVE INCREASED POPS TO BETWEEN 40 TO 50 ACROSS THE CWFA. COLDER AIR WILL FILTER IN MONDAY NIGHT AND ESPECIALLY TUESDAY...WILL CONTINUE TO INDICATE SNOW MIXING IN DURING THE TAIL OF THE PRECIP MONDAY NIGHT WITH SOME UPSLOPE SNOW SHOWERS POSSIBLE ALONG THE ALLEGHENY FRONT ON TUESDAY. HAVE BACKED OFF THE POPS PREVIOUSLY INDICATED TUE AND TUE NIGHT EAST OF THE RIDGE WHERE MOISTURE WILL PROBABLY BE LACKING.

TEMPS WILL BE WELL ABOVE NORMAL FRI THROUGH MON IN SOUTHWESTERLY FLOW. 00Z GFS AND ESPECIALLY THE LATEST ECMWF CONTINUE TO SHOW A NICE CHUNK OF ARCTIC AIR DROPPING INTO THE MIDWEST WITH THIS SYSTEM MON-TUE...BUT STILL NOT CONVINCED AIRMASS WILL REMAIN INTACT OR FOR THAT MATTER MAKE IT TO THE MID ATLANTIC TO BRING US SOME MORE REALISTIC MID-WINTER CONDITIONS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR MDZ501.

VA...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ021.

WV...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR WVZ054-501-503.

MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR ANZ530>537.

&&

$$

SHORT TERM/HYDROLOGY/AVIATION/TIDES...ROGOWSKI LONG TERM...BROTHERTON MARINE...ROGOWSKI/BROTHERTON

.SHORT TERM (TODAY AND TONIGHT)... WATER VAPOR LOOP SHOWS A LONG WAVE TROUGH MOVING EAST OF THE REGION...WITH A RIDGE ACROSS THE ROCKIES. ACARS 400-250MB WIND OBSERVATIONS REVEAL A NORTHWEST JET OF 140-170KT FEEDING INTO THE BASE OF THE TROUGH FROM SOUTH CENTRAL CANADA THROUGH THE MID ATLANTIC. 04Z SURFACE ANALYSIS PLACED A TROUGH IN THE LEE OF THE APPALACHIANS...WITH A 1032MB ANTICYCLONE ACROSS THE SOUTH CENTRAL CONUS. SEVERAL NEARLY STATIONARY WEST-EAST BOUNDARIES WERE DRAPED ACROSS SOUTH CENTRAL CANADA AND UPPER MIDWEST.

WHILE 03Z SHORT RANGE ENSEMBLES AND 00Z NAM INDICATE ADDITIONAL SNOW WATER EQUIVALENT OF A TENTH OF AN INCH ACROSS THE MOUNTAINS EARLY THIS MORNING...NATIONAL RADAR LOOP SHOWS STREAMERS STILL COMING OFF THE GREAT LAKES. HAVE THEREFORE EXTENDED THE SNOW ADVISORY UNTIL 10:00 AM FOR AN ADDITIONAL 1-2" OF SNOW IN THE FAVORED UPSLOPE LOCATIONS. WITH ANTICYCLONIC FLOW SUPPORTED BY RIDGE BUILDING IN THIS AFTERNOON...WARM ADVECTION AND LOW LEVEL SHEAR WILL DIMINISH REMAINING SNOW SHOWERS AND MUCH OF THE UPSLOPE CLOUDINESS.

EAST OF THE MOUNTAINS...STEEP LOW LEVEL LAPSE RATES ARE SUPPORTING ISOLATED FLURRIES EARLY THIS MORNING. THESE FLURRIES WILL DIMINISH SHORTLY AFTER SUNRISE AS UPSLOPE SNOW SHOWERS BECOME LESS NUMEROUS AND EFFICIENT. CLOUDS WILL BE BREAKING EARLY THIS MORNING...WITH SOME REDEVELOPMENT OF CUMULUS DURING THE LATE MORNING. WITH STRONG COLD ADVECTION...WENT BELOW MOS FOR HIGH TEMPERATURES.

SKY WILL BECOME CLEAR ACROSS THE REGION BY LATE EVENING AS HIGH PRESSURE SURFACE AND ALOFT SETTLES INTO THE MID ATLANTIC. LOOSENING GRADIENT WILL ALLOW WINDS TO DECOUPLE...AND WITH DRY AIRMASS WILL SEE GREAT RADIATIONAL COOLING. ANTICIPATE SINGLE DIGITS IN FAR WESTERN VALLEYS...MID TEENS RURAL AREAS...LOW TO MID 20S ACROSS THE CITIES AND UPPER TEENS ABOVE 2500FT.

&&

.AVIATION... GRADIENT WILL SUPPORT NW WIND GUSTS TO 25KTS TODAY...WITH ISOLATED FLURRIES POSSIBLE FROM STRATOCU DECK NORTH OF KCHO EARLY THIS MORNING (NO REDUCTION OF CEILINGS OR VISIBILITIES ARE ANTICIPATED). BUILDING RIDGE WILL ALLOW CLOUDS TO DIMINISH AS WINDS DECOUPLE THIS EVENING.

&&

.MARINE... 00Z GFS/ETA MOS AT THOMAS POINT BOTH SUGGEST SUSTAINED WINDS WILL BE IN THE 19-22KT RANGE TODAY...AND AROUND 10KT RANGE TONIGHT. 00Z NAM/GFS PROXIMITY LAND BUFKIT FORECAST SOUNDINGS SUGGEST ADDITIONAL WIND GUST MOMENTUM OF 24-28KT. WILL HAVE WINDS OF 20-25KT IN THE FORECAST TODAY...WITH THE SMALL CRAFT ADVISORY CONTINUING UNTIL EARLY EVENING.

PARTIAL DOWNSLOPE THU NIGHT INTO FRI AND A DECENT PRES GRAD BEHIND THE DEPARTING HIGH PRES. CONCERNED ABOUT POSSIBLE SCA WINDS DEVELOPING BUT FOR NOW NOT HIGH ENOUGH CONFIDENCE AND NOT ANY PERSUASIVE MODEL WIND DATA ATTM TO MENTION IN THE FCST...WILL JUST NEED TO KEEP AN EYE ON LATER RUNS.

GRAD TIGHTENS AGAIN AROUND SUNDAY BETWEEN OH VLY LOW AND ATLC HIGH AND GOOD SW WINDS...WITH ANOTHER POSSIBLE SCA HEADLINE.

&&

.TIDES... WATER LEVELS ARE CURRENTLY A QUARTER FOOT ABOVE ASTRONOMIC PREDICTIONS. THE LUNAR CYCLE IS WANING TOWARD A QUARTER MOON (63% FULL). THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM AND NOAA EXTRATROPICAL STORM SURGE MODEL FORECAST WATER LEVELS TO FALL TO DEPARTURES OF ONE FOOT BELOW ASTRONOMIC WATER LEVELS THIS AFTERNOON WITH STRONG NORTHWEST FLOW.

&&

.LONG TERM...THURSDAY THROUGH TUESDAY...

THU-FRI HIGH PRES WILL MOVE OFFSHORE AND ALLOW WARM SW FLOW TO DEVELOP ACROSS THE MID ATLANTIC. 850 WINDS WILL INCREASE TO NEAR 50 KT ON SUN AS A WARM FRONT MOVES NORTH OF THE REGION ASSOCIATED WITH THE DEEPENING LOW OVER THE LOWER OHIO VALLEY. STILL MOISTURE TRANSPORT OVER THE VIRGINIAS IS PRETTY POOR AND DON`T SEE MUCH IN THE WAY OF PRECIPITATION FOR THE STERLING CWFA IN THIS WARM SECTOR...TIL THE STRONG COLD FRONT APPROACHES SUN NIGHT. BETTER CHANCES ON MONDAY AS FRONT DEVELOPS AN IMPRESSIVE POOL OF LIFT ACROSS MD/VA. WITH SOME RUN-RUN CONSISTENCY IN MONDAY PRECIP CHANCES HAVE INCREASED POPS TO BETWEEN 40 TO 50 ACROSS THE CWFA. COLDER AIR WILL FILTER IN MONDAY NIGHT AND ESPECIALLY TUESDAY...WILL CONTINUE TO INDICATE SNOW MIXING IN DURING THE TAIL OF THE PRECIP MONDAY NIGHT WITH SOME UPSLOPE SNOW SHOWERS POSSIBLE ALONG THE ALLEGHENY FRONT ON TUESDAY. HAVE BACKED OFF THE POPS PREVIOUSLY INDICATED TUE AND TUE NIGHT EAST OF THE RIDGE WHERE MOISTURE WILL PROBABLY BE LACKING.

TEMPS WILL BE WELL ABOVE NORMAL FRI THROUGH MON IN SOUTHWESTERLY FLOW. 00Z GFS AND ESPECIALLY THE LATEST ECMWF CONTINUE TO SHOW A NICE CHUNK OF ARCTIC AIR DROPPING INTO THE MIDWEST WITH THIS SYSTEM MON-TUE...BUT STILL NOT CONVINCED AIRMASS WILL REMAIN INTACT OR FOR THAT MATTER MAKE IT TO THE MID ATLANTIC TO BRING US SOME MORE REALISTIC MID-WINTER CONDITIONS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR MDZ501.

VA...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ021.

WV...SNOW ADVISORY UNTIL 10 AM EST THIS MORNING FOR WVZ054-501-503.

MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR ANZ530>537.

&&

$$

SHORT TERM/HYDROLOGY/AVIATION/TIDES...ROGOWSKI LONG TERM...BROTHERTON MARINE...ROGOWSKI/BROTHERTON

.UPDATE...SFC TEMPERATURES ARE HOLDING ABOVE FREEZING STILL...AND WITH UPSTREAM MIDDLE 30S DEW POINTS MOVING IN AND SUBTLE WARMING OR NEAR STEADY TEMPERATURES ANTICIPATED...FREEZING DRIZZLE WILL ONLY BE A CONCERN FOR INTERIOR LOCATIONS OF EASTERN UPPER MICHIGAN.

HAVE REMOVED THE FREEZING PRECIPITATION FORECAST IN THE LATEST FORECAST ISSUANCE. AREAS OF LIGHT RAIN AND DRIZZLE WILL CONTINUE TO EXPAND EASTWARD TONIGHT. CEILINGS WILL ALSO BE LOWER THAN ANTICIPATED...WITH 2-5KFT OVERCAST CONDITIONS BEING COMMON FOR A PERIOD TONIGHT. STRONGER MID LEVEL DRYING EXPECTED TO END DRIZZLE LATE TONIGHT IN SOME AREAS ACROSS NW LOWER...AND POSSIBLY INTO NE LOWER BY DAYBREAK. SMD

&&

.PREVIOUS DISCUSSION ISSUED AT 833 PM EST THU JAN 11 2007 UPDATE...SFC/RUC/SATELLITE/RADAR AND UPPER AIR ANALYSIS SHOWING POSITIVELY TILTED MID LEVEL TROUGH ACROSS THE NRN ROCKIES WITH LONG STRETCH OF WARMER WSW FLOW FROM THE FOUR CORNERS REGION THROUGH THE CENTRAL PLAINS AND INTO THE GREAT LAKES/NORTHEAST CONUS. WEAK SHORTWAVE ENERGY RUNNING THROUGH THIS WSW FLOW ALOFT...AND SFC LOW PRESSURE SEEN SOUTH OF JAMES BAY...AND ANOTHER PUSHING THROUGH SRN WISCONSIN. BOTH ARE CONNECTED BY A COLD FRONT (TEMPERATURES DROPPING LIKE CRAZY OUT IN THE NORTHERN AND CENTRAL PLAINS WITH READINGS IN THE SINGLE DIGITS BELOW ZERO). THE LATTER SFC LOW IS ASSOCIATED WITH A SEEMINGLY MORE DEFINED VORTICITY MAX IDENTIFIED IN WV IMAGERY...AS WELL AS BETTER PUSH OF LOW LEVEL MOISTURE. UPSTREAM OBS IN THIS AREA SHOWING SFC TD`S CLIMBING INTO THE MIDDLE 30S...AND NUMEROUS REPORTS OF DRIZZLE/LIGHT RAIN...WITH RAIN AMOUNTS FROM A TRACE TO A FEW HUNDREDTHS.

FORECAST WAS CALLING FOR THIS AREA OF MEASURABLE RAINFALL (0.01" OR GREATER)...TO SWING UP ACROSS MAINLY THE SRN HALF OF THE CWA. LATEST EXTRAPOLATIONS SUGGEST THAT THIS MAY BE A BIT OPTIMISTIC...AS THE TREND IS SHOWING THAT THIS AREA OF RAIN MAY SLIDE BY TO OUR SOUTH. LOOKING AT FORECAST SOUNDINGS...AND MORE IMPORTANTLY...AREA TAMDAR SOUNDINGS SHOW THAT MOISTURE COMING FROM UPSTREAM WILL ALL BE BELOW THE -10C ISOTHERM...SUGGESTING A DRIZZLE SITUATION. CEILINGS ARE NOT VERY LOW WITH THIS STUFF RIGHT NOW (AOA 2500 FEET)...SO THE EFFECT ON VISIBILITIES IS NOT EXPECTED TO AMOUNT TO MUCH. RATHER...PATCHY LIGHT RAIN/DRIZZLE...MORE COMMON ON THE HIGHER TERRAIN AND ACROSS THE SRN CWA IS MORE THE RULE. SO...CANNOT ARGUE THE CURRENT CHANCE OF PRECIPITATION...BUT HAVE JUST ELIMINATED THE SNOW MENTION IN THE FORECAST. THE BEST CHANCE FOR SEEING THIS PRECIPITATION WILL BE LATE THIS EVENING ACROSS THE GTV BAY REGION AND SOUTH...THEN ACROSS THE REMAINDER OF NRN LOWER AND EASTERN UPPER AS WE HEAD INTO THE OVERNIGHT HOURS. THE ONLY CHANCE IT SEEMS FOR A TOUCH OF SNOW TO FALL WOULD BE WITH THE COLD FRONT THAT MAY SNEAK INTO WESTERN PORTIONS OF CHIPPEWA AND MACKINAC COUNTIES LATE TONIGHT OR TOWARD DAYBREAK...WHERE IT`S PRESENCE MAY RESULT IN SLIGHT BETTER LIFT THAN THE MODELS CAN RESOLVE (INTO/PAST THE -10C ISOTHERM).

FINALLY...EXPANDED THE PATCHY FREEZING DRIZZLE FOR THE TIME BEING...BUT WILL HAVE TO CLOSELY MONITOR THE TEMPERATURE TRENDS THROUGH THE NIGHT. IT WILL BE POSSIBLE IN TYPICALLY COLDER LOCALES PRETTY MUCH ANYWHERE IN INTERIOR NRN LOWER AND EASTERN UPPER. LOOKING AT UPSTREAM SFC TD`S THOUGH (MID 30`S)...MAY HAVE TO TRIM BACK AREAS WHERE THIS COULD OCCUR...RESULTING IN A POSSIBLE SECOND UPDATE LATER TONIGHT. LEAST CONFIDENCE RESIDES IN THE FREEZING PRECIP SITUATION. SMD

&&

.PREV DISCUSSION ISSUED AT 356 PM EST THU JAN 11 2007 DISCUSSION...THE SFC LOW IS OVER LAKE SUPERIOR WITH A 500 MB SPEED MAX NORTH OF LAKE SUPERIOR AND A SECOND SFC LOW IN KANSAS WITH A SECOND SPEED MAX AT 500 MB. THIS ENTIRE SYSTEM IS SLOWLY MOVING EAST OVER THE GREAT LAKES AND WILL BE THE MAIN CONCERN FOR THE FORECAST PACKAGE, EXCEPT THE WAVE THAT IS EXPECT TO DEVELOP OVER THE FRONT THAT CONNECTS THE SFC LOWS CURRENTLY, WHICH IS A CONCERN FOR MONDAY.

MODELS HAVE FEW DIFFERENCES OVER THE FORECAST AREA THROUGH THE 84 HOURS OF THE MAIN FORECAST PACKAGE, EXCEPT FOR SOME MOISTURE ISSUES OVERNIGHT WHICH IS CAUSING A BIT OF A HEADACHE FOR P-TYPE PROBLEMS OVERNIGHT AND FRIDAY.

TONIGHT...MOISTURE CONTINUES TO ADVECT UP FROM THE SW INTO LOWER MICHIGAN SO THAT BY 00Z THE 850 MB RH IS OVER 90%. THIS IS EVIDENT ACROSS N ILLINOIS AND S LOWER WHERE THE CLOUDS ARE AROUND 4000 FT. THESE WILL CONTINUE TO MOVE UP INTO THE REGION. THE MOISTURE, HOWEVER, BARELY MAKES -10C OVERNIGHT AND WITH ALL OF THE WINDS ALOFT (850 MB WINDS 30-40KTS) WOULD EXPECT THAT IF THE MOISTURE DOESN`T REACH -10C THAT DRIZZLE WILL RESULT. SFC TEMPERATURES A FALLING SO SLOWLY THAT THE M-32 CORRIDOR DOESN`T GO BELOW FREEZING UNTIL ABOUT 10Z AND THE M-55 CORRIDOR DOESN`T COOL TO BELOW FREEZING UNTIL 12Z. SO FOR THE MOST PART THERE WILL BE A MIX OF P-TYPES WITH JUST CHANCE THAT ANY OF IT WILL BE MEASURABLE.

FRIDAY...THE COLD AIR BEGINS TO MAKE IT INTO THE REGION. THERE WILL BE A LAG AS THE 700-500 MB MOISTURE STRIPS OUT FIRST BEFORE THE -10C LEVEL DESCENDS FULLY INTO THE MOISTURE. SO THE RAIN WILL LESSEN AND THERE WILL BE MORE DRIZZLE AND FREEZING DRIZZLE, BUT SNOW WILL BE A POSSIBILITY, ESPECIALLY AS WE GET LATER INTO THE AFTERNOON. BY 00Z, THE -10C LINE IS AT 850 MB WITH THE RH ON BOTH MODELS AT OR ABOVE 80% SO BY THE LATE AFTERNOON WOULD EXPECT THAT NORTHERN PART OF THE FORECAST AREA WILL SEE SOME SNOW.

LUTZ

FRIDAY NIGHT...COLD FRONT CONTINUES TO SAG INTO THE OHIO VALLEY DURING THE NIGHT WHILE HIGH PRESSURE AND A FAIRLY DRY WEDGE OF AIR BUILD ACROSS NRN MICHIGAN. MEANWHILE...COLD ADVECTION BEHIND THE FRONT SENDS 850 MB TEMPS INTO THE -12C TO -16C RANGE PRODUCING LAKE-850 MB DELTA T/S IN THE HIGH TEENS TO AROUND 20C. NOT BAD FROM AN INSTABILITY STANDPOINT. BUT...COLD AIR IS A BIT ON THE SHALLOW SIDE (MAINLY BLO 850 MB) WITH A SHARP SUBSIDENCE INVERSION ABOVE AND MEAN 850-700 MB RH VALUES LOWERING TO < 25 PERCENT THROUGH THE NIGHT. NOT EXACTLY CONDUCIVE TO GREAT LAKE EFFECT. NONETHELESS WE SHOULD GET SOME SCT-NMRS SNOW SHOWERS GOING OFF LAKE SUPERIOR AND LAKE MICHIGAN PARTICULARLY DURING THE EVENING AND EARLY OVERNIGHT HOURS BEFORE THE DRY AIR/ANTICYCLONIC FLOW REALLY TAKES HOLD. BUT GIVEN THE NEGATIVE FACTORS...THINK ACCUMULATIONS WILL BE HELD TO UNDER AN INCH IN THE SNOW BELT AREAS OF NW LOWER AND EASTERN UPPER.

SATURDAY AND SATURDAY NIGHT...DESPITE DECENT OVER LAKE INSTABILITY CONDITIONS JUST GET INCREASINGLY HOSTILE FOR LAKE EFFECT SNOW SHOWERS ON SATURDAY...AS THE LOW LEVEL RIDGE AXIS AND DRY AIR SETTLES IN ACROSS NRN MICHIGAN. FORECAST NNW MEAN LOW LEVEL FLOW TO START THE DAY SHOULD CONTINUE TO BRING A FEW SNOW SHOWERS OR FLURRIES TO A PORTION OF NW LOWER MICHIGAN (EAST OF U.U. 131) AND EASTERN UPPER AROUND WHITEFISH POINT. BUT FOR THE AFTERNOON WITH THE FLOW BECOMING LIGHT AND ALL OVER THE PLACE...HAVE REMOVED POPS ENTIRELY AND WE SHOULD SEE SOME SUN ACROSS THE REGION. ON SATURDAY NIGHT...WEAK NRN STREAM COLD FRONT FORECAST TO SLIP SOUTH ACROSS LAKE SUPERIOR OVERNIGHT...AND WE MAY GET A BIT OF A MOISTURE SURGE FROM THE FRONTAL ZONE TO THE SOUTH. WITH MEAN LOW LEVEL FLOW FROM THE SW VEERING WEST...MIGHT BE ENOUGH TO RE-KINDLE SOME LIGHT SNOW SHOWERS OFF LAKE MICHIGAN DURING THE NIGHT.

SUNDAY THRU THURSDAY...SPLIT FLOW REGIME ACROSS THE LOWER 48 STATES TO START THE PERIOD WITH A CLOSED MID LEVEL LOW MIGRATING INTO THE PLAINS...AND FLOW RECOMBINING ACROSS THE GREAT LAKES. MEANWHILE... BROAD NRN STREAM HIGH PRESSURE EXPECTED TO BE ACROSS THE NRN TIER OF STATES AND WESTERN GREAT LAKES ON SUNDAY WITH PERHAPS A WEAK NRN STREAM COLD FRONT WASHING OUT ACROSS LAKE SUPERIOR...AND BAROCLINIC ZONE BECOMING ACTIVE ACROSS THE OHIO VALLEY IN ADVANCE OF APPROACHING MID LEVEL WAVE. OF COURSE...BIGGEST FORECAST ISSUE REVOLVES AROUND ULTIMATE POSITION OF THE BAROCLINIC ZONE...AND DEVELOPMENT/TRACK OF RESPECTABLE SRN STREAM STORM SYSTEM THROUGH THE OHIO VALLEY LATE SUNDAY THROUGH MONDAY. MODEL TRENDS OVER THE LAST 2 DAYS HAS SUPPRESSED THIS SYSTEM SOUTH...PARTICULARLY THE GFS WHICH KEEPS BULK OF PRECIP NEARLY OUT OF NRN MICHIGAN. HOWEVER... WOULD NOT BE PRUDENT TO DISMISS THIS SYSTEM AT THIS JUNCTURE AS A SLIGHTLY NORTHWARD NUDGE WOULD MAKE A BIG DIFFERENCE...AND WE ARE STILL CLOSE ENOUGH TO GET LAKE HURON INTO THE ACT. SO...WILL CONTINUE TO MENTION THE POSSIBILITIES IN THE HAZARDOUS WEATHER OUTLOOK FOR NOW AND SEE WHAT HAPPENS. BEHIND THIS SYSTEM...SOME OF THE COLDEST AIR OF THE SEASON GETS PULLED DOWN INTO THE GREAT LAKES NRN MICHIGAN FOR TUESDAY AND WEDNESDAY...WHILE STRONG HIGH PRESSURE BUILDS INTO THE PLAINS AND WESTERN GREAT LAKES. SOME HINT OF A CLIPPER TYPE SYSTEM PASSING THROUGH THE STATE LATE TUESDAY/EARLY WEDNESDAY TIMEFRAME. BUT REGARDLESS...WITH VERY COLD AIR IN PLACE WILL CONTINUE WITH SNOW SHOWER CHANCES THROUGH THE MID PART OF THE WEEK. CORE OF COLDEST AIR MAY PULL OUT OF THE REGION ON THURSDAY ALTHOUGH ANOTHER NRN STREAM CLIPPER SYSTEM MAY IMPACT THE REGION.

ADAM

&&

.APX...WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

.UPDATE...SFC/RUC/SATELLITE/RADAR AND UPPER AIR ANALYSIS SHOWING POSITIVELY TILTED MID LEVEL TROUGH ACROSS THE NRN ROCKIES WITH LONG STRETCH OF WARMER WSW FLOW FROM THE FOUR CORNERS REGION THROUGH THE CENTRAL PLAINS AND INTO THE GREAT LAKES/NORTHEAST CONUS. WEAK SHORTWAVE ENERGY RUNNING THROUGH THIS WSW FLOW ALOFT...AND SFC LOW PRESSURE SEEN SOUTH OF JAMES BAY...AND ANOTHER PUSHING THROUGH SRN WISCONSIN. BOTH ARE CONNECTED BY A COLD FRONT (TEMPERATURES DROPPING LIKE CRAZY OUT IN THE NORTHERN AND CENTRAL PLAINS WITH READINGS IN THE SINGLE DIGITS BELOW ZERO). THE LATTER SFC LOW IS ASSOCIATED WITH A SEEMINGLY MORE DEFINED VORTICITY MAX IDENTIFIED IN WV IMAGERY...AS WELL AS BETTER PUSH OF LOW LEVEL MOISTURE. UPSTREAM OBS IN THIS AREA SHOWING SFC TD`S CLIMBING INTO THE MIDDLE 30S...AND NUMEROUS REPORTS OF DRIZZLE/LIGHT RAIN...WITH RAIN AMOUNTS FROM A TRACE TO A FEW HUNDREDTHS.

FORECAST WAS CALLING FOR THIS AREA OF MEASURABLE RAINFALL (0.01" OR GREATER)...TO SWING UP ACROSS MAINLY THE SRN HALF OF THE CWA. LATEST EXTRAPOLATIONS SUGGEST THAT THIS MAY BE A BIT OPTIMISTIC...AS THE TREND IS SHOWING THAT THIS AREA OF RAIN MAY SLIDE BY TO OUR SOUTH. LOOKING AT FORECAST SOUNDINGS...AND MORE IMPORTANTLY...AREA TAMDAR SOUNDINGS SHOW THAT MOISTURE COMING FROM UPSTREAM WILL ALL BE BELOW THE -10C ISOTHERM...SUGGESTING A DRIZZLE SITUATION. CEILINGS ARE NOT VERY LOW WITH THIS STUFF RIGHT NOW (AOA 2500 FEET)...SO THE EFFECT ON VISIBILITIES IS NOT EXPECTED TO AMOUNT TO MUCH. RATHER...PATCHY LIGHT RAIN/DRIZZLE...MORE COMMON ON THE HIGHER TERRAIN AND ACROSS THE SRN CWA IS MORE THE RULE. SO...CANNOT ARGUE THE CURRENT CHANCE OF PRECIPITATION...BUT HAVE JUST ELIMINATED THE SNOW MENTION IN THE FORECAST. THE BEST CHANCE FOR SEEING THIS PRECIPITATION WILL BE LATE THIS EVENING ACROSS THE GTV BAY REGION AND SOUTH...THEN ACROSS THE REMAINDER OF NRN LOWER AND EASTERN UPPER AS WE HEAD INTO THE OVERNIGHT HOURS. THE ONLY CHANCE IT SEEMS FOR A TOUCH OF SNOW TO FALL WOULD BE WITH THE COLD FRONT THAT MAY SNEAK INTO WESTERN PORTIONS OF CHIPPEWA AND MACKINAC COUNTIES LATE TONIGHT OR TOWARD DAYBREAK...WHERE IT`S PRESENCE MAY RESULT IN SLIGHT BETTER LIFT THAN THE MODELS CAN RESOLVE (INTO/PAST THE -10C ISOTHERM).

FINALLY...EXPANDED THE PATCHY FREEZING DRIZZLE FOR THE TIME BEING...BUT WILL HAVE TO CLOSELY MONITOR THE TEMPERATURE TRENDS THROUGH THE NIGHT. IT WILL BE POSSIBLE IN TYPICALLY COLDER LOCALES PRETTY MUCH ANYWHERE IN INTERIOR NRN LOWER AND EASTERN UPPER. LOOKING AT UPSTREAM SFC TD`S THOUGH (MID 30`S)...MAY HAVE TO TRIM BACK AREAS WHERE THIS COULD OCCUR...RESULTING IN A POSSIBLE SECOND UPDATE LATER TONIGHT. LEAST CONFIDENCE RESIDES IN THE FREEZING PRECIP SITUATION. SMD

&&

.PREV DISCUSSION ISSUED AT 356 PM EST THU JAN 11 2007 DISCUSSION...THE SFC LOW IS OVER LAKE SUPERIOR WITH A 500 MB SPEED MAX NORTH OF LAKE SUPERIOR AND A SECOND SFC LOW IN KANSAS WITH A SECOND SPEED MAX AT 500 MB. THIS ENTIRE SYSTEM IS SLOWLY MOVING EAST OVER THE GREAT LAKES AND WILL BE THE MAIN CONCERN FOR THE FORECAST PACKAGE, EXCEPT THE WAVE THAT IS EXPECT TO DEVELOP OVER THE FRONT THAT CONNECTS THE SFC LOWS CURRENTLY, WHICH IS A CONCERN FOR MONDAY.

MODELS HAVE FEW DIFFERENCES OVER THE FORECAST AREA THROUGH THE 84 HOURS OF THE MAIN FORECAST PACKAGE, EXCEPT FOR SOME MOISTURE ISSUES OVERNIGHT WHICH IS CAUSING A BIT OF A HEADACHE FOR P-TYPE PROBLEMS OVERNIGHT AND FRIDAY.

TONIGHT...MOISTURE CONTINUES TO ADVECT UP FROM THE SW INTO LOWER MICHIGAN SO THAT BY 00Z THE 850 MB RH IS OVER 90%. THIS IS EVIDENT ACROSS N ILLINOIS AND S LOWER WHERE THE CLOUDS ARE AROUND 4000 FT. THESE WILL CONTINUE TO MOVE UP INTO THE REGION. THE MOISTURE, HOWEVER, BARELY MAKES -10C OVERNIGHT AND WITH ALL OF THE WINDS ALOFT (850 MB WINDS 30-40KTS) WOULD EXPECT THAT IF THE MOISTURE DOESN`T REACH -10C THAT DRIZZLE WILL RESULT. SFC TEMPERATURES A FALLING SO SLOWLY THAT THE M-32 CORRIDOR DOESN`T GO BELOW FREEZING UNTIL ABOUT 10Z AND THE M-55 CORRIDOR DOESN`T COOL TO BELOW FREEZING UNTIL 12Z. SO FOR THE MOST PART THERE WILL BE A MIX OF P-TYPES WITH JUST CHANCE THAT ANY OF IT WILL BE MEASURABLE.

FRIDAY...THE COLD AIR BEGINS TO MAKE IT INTO THE REGION. THERE WILL BE A LAG AS THE 700-500 MB MOISTURE STRIPS OUT FIRST BEFORE THE -10C LEVEL DESCENDS FULLY INTO THE MOISTURE. SO THE RAIN WILL LESSEN AND THERE WILL BE MORE DRIZZLE AND FREEZING DRIZZLE, BUT SNOW WILL BE A POSSIBILITY, ESPECIALLY AS WE GET LATER INTO THE AFTERNOON. BY 00Z, THE -10C LINE IS AT 850 MB WITH THE RH ON BOTH MODELS AT OR ABOVE 80% SO BY THE LATE AFTERNOON WOULD EXPECT THAT NORTHERN PART OF THE FORECAST AREA WILL SEE SOME SNOW.

LUTZ

FRIDAY NIGHT...COLD FRONT CONTINUES TO SAG INTO THE OHIO VALLEY DURING THE NIGHT WHILE HIGH PRESSURE AND A FAIRLY DRY WEDGE OF AIR BUILD ACROSS NRN MICHIGAN. MEANWHILE...COLD ADVECTION BEHIND THE FRONT SENDS 850 MB TEMPS INTO THE -12C TO -16C RANGE PRODUCING LAKE-850 MB DELTA T/S IN THE HIGH TEENS TO AROUND 20C. NOT BAD FROM AN INSTABILITY STANDPOINT. BUT...COLD AIR IS A BIT ON THE SHALLOW SIDE (MAINLY BLO 850 MB) WITH A SHARP SUBSIDENCE INVERSION ABOVE AND MEAN 850-700 MB RH VALUES LOWERING TO < 25 PERCENT THROUGH THE NIGHT. NOT EXACTLY CONDUCIVE TO GREAT LAKE EFFECT. NONETHELESS WE SHOULD GET SOME SCT-NMRS SNOW SHOWERS GOING OFF LAKE SUPERIOR AND LAKE MICHIGAN PARTICULARLY DURING THE EVENING AND EARLY OVERNIGHT HOURS BEFORE THE DRY AIR/ANTICYCLONIC FLOW REALLY TAKES HOLD. BUT GIVEN THE NEGATIVE FACTORS...THINK ACCUMULATIONS WILL BE HELD TO UNDER AN INCH IN THE SNOW BELT AREAS OF NW LOWER AND EASTERN UPPER.

SATURDAY AND SATURDAY NIGHT...DESPITE DECENT OVER LAKE INSTABILITY CONDITIONS JUST GET INCREASINGLY HOSTILE FOR LAKE EFFECT SNOW SHOWERS ON SATURDAY...AS THE LOW LEVEL RIDGE AXIS AND DRY AIR SETTLES IN ACROSS NRN MICHIGAN. FORECAST NNW MEAN LOW LEVEL FLOW TO START THE DAY SHOULD CONTINUE TO BRING A FEW SNOW SHOWERS OR FLURRIES TO A PORTION OF NW LOWER MICHIGAN (EAST OF U.U. 131) AND EASTERN UPPER AROUND WHITEFISH POINT. BUT FOR THE AFTERNOON WITH THE FLOW BECOMING LIGHT AND ALL OVER THE PLACE...HAVE REMOVED POPS ENTIRELY AND WE SHOULD SEE SOME SUN ACROSS THE REGION. ON SATURDAY NIGHT...WEAK NRN STREAM COLD FRONT FORECAST TO SLIP SOUTH ACROSS LAKE SUPERIOR OVERNIGHT...AND WE MAY GET A BIT OF A MOISTURE SURGE FROM THE FRONTAL ZONE TO THE SOUTH. WITH MEAN LOW LEVEL FLOW FROM THE SW VEERING WEST...MIGHT BE ENOUGH TO RE-KINDLE SOME LIGHT SNOW SHOWERS OFF LAKE MICHIGAN DURING THE NIGHT.

SUNDAY THRU THURSDAY...SPLIT FLOW REGIME ACROSS THE LOWER 48 STATES TO START THE PERIOD WITH A CLOSED MID LEVEL LOW MIGRATING INTO THE PLAINS...AND FLOW RECOMBINING ACROSS THE GREAT LAKES. MEANWHILE... BROAD NRN STREAM HIGH PRESSURE EXPECTED TO BE ACROSS THE NRN TIER OF STATES AND WESTERN GREAT LAKES ON SUNDAY WITH PERHAPS A WEAK NRN STREAM COLD FRONT WASHING OUT ACROSS LAKE SUPERIOR...AND BAROCLINIC ZONE BECOMING ACTIVE ACROSS THE OHIO VALLEY IN ADVANCE OF APPROACHING MID LEVEL WAVE. OF COURSE...BIGGEST FORECAST ISSUE REVOLVES AROUND ULTIMATE POSITION OF THE BAROCLINIC ZONE...AND DEVELOPMENT/TRACK OF RESPECTABLE SRN STREAM STORM SYSTEM THROUGH THE OHIO VALLEY LATE SUNDAY THROUGH MONDAY. MODEL TRENDS OVER THE LAST 2 DAYS HAS SUPPRESSED THIS SYSTEM SOUTH...PARTICULARLY THE GFS WHICH KEEPS BULK OF PRECIP NEARLY OUT OF NRN MICHIGAN. HOWEVER... WOULD NOT BE PRUDENT TO DISMISS THIS SYSTEM AT THIS JUNCTURE AS A SLIGHTLY NORTHWARD NUDGE WOULD MAKE A BIG DIFFERENCE...AND WE ARE STILL CLOSE ENOUGH TO GET LAKE HURON INTO THE ACT. SO...WILL CONTINUE TO MENTION THE POSSIBILITIES IN THE HAZARDOUS WEATHER OUTLOOK FOR NOW AND SEE WHAT HAPPENS. BEHIND THIS SYSTEM...SOME OF THE COLDEST AIR OF THE SEASON GETS PULLED DOWN INTO THE GREAT LAKES NRN MICHIGAN FOR TUESDAY AND WEDNESDAY...WHILE STRONG HIGH PRESSURE BUILDS INTO THE PLAINS AND WESTERN GREAT LAKES. SOME HINT OF A CLIPPER TYPE SYSTEM PASSING THROUGH THE STATE LATE TUESDAY/EARLY WEDNESDAY TIMEFRAME. BUT REGARDLESS...WITH VERY COLD AIR IN PLACE WILL CONTINUE WITH SNOW SHOWER CHANCES THROUGH THE MID PART OF THE WEEK. CORE OF COLDEST AIR MAY PULL OUT OF THE REGION ON THURSDAY ALTHOUGH ANOTHER NRN STREAM CLIPPER SYSTEM MAY IMPACT THE REGION.

ADAM

&&

.APX...WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

.DISCUSSION....EARLY THIS AFTERNOON...LATEST SURFACE/RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW HIGH PRESSURE OVER THE SOUTHERN PLAINS WHOSE SURFACE RIDGE AXIS BISECTS LOWER MICHIGAN. LOW LEVEL WINDS STARTING TO REFLECT THE AXIS PASSAGE WITH LIGHT LAKE EFFECT SNOW SHOWERS OVER NW LOWER AND TIP OF THE MITT DIMINISHING AS THE DISORGANIZED BANDS ARE TRYING TO ORIENT THEMSELVES IN THE SW-NE DIRECTION. THESE BANDS ARE ALSO FIGHTING PLENTY OF DRY AIR AS ACARS SOUNDINGS FROM PLN AND TVC SHOW INVERSION HEIGHTS CONTINUING TO FALL TO AROUND 860MB. AWAY FROM THE LES BANDS...SKIES HAVE TURNED PARTLY TO MOSTLY SUNNY. MEANWHILE UPSTREAM...STRONG SHORTWAVE NOW OVER ALBERTA AND ASSOCIATED LOW PRESSURE IS TRUCKING EAST ALONG THE CANADIAN BORDER...HELPING TO TIGHTEN THE PRESSURE GRADIENT OVER THE PLAINS. WARM AIR ADVECTION CLOUDS RIDING OVER THE 850MB WARM FRONT LOCATED OVER THE UPPER MISSISSIPPI RIVER VALLEY ARE STARTING TO CROSS LAKE MICHIGAN...AND WILL EVENTUALLY MAKE IT ACROSS THE CWA LATE THIS AFTERNOON/EVENING. THE INTERACTION OF THIS WARM FRONT AS IT MOVES NORTHEAST TONIGHT...AND WEAKENING LES WILL BE THE MAIN FORECAST CONCERN TONIGHT.

TONIGHT...UPSTREAM SHORTWAVE WILL MAKE IT TO MANITOBA (ASSOCIATED SURFACE LOW PRESSURE TO WESTERN ONTARIO) BY 12Z THURSDAY MORNING. THIS WAVE WILL HELP INCREASE THE SOUTHERLY FLOW AHEAD OF IT AND PUSH A 850MB WARM FRONT TO THE NORTHEAST TO NORTHERN LOWER BY 12Z. AS IT DOES SO...850MB TEMPERATURES MODERATE ALOT FROM MINUS 6-9C AT 00Z OVER NORTHERN LAKE MICHIGAN TO 0 TO MINUS 3 BY 12Z. A SURGE OF MOISTURE WILL ACCOMPANY THIS WAA...WHICH REDUCES CONDENSATION PRESSURE DEFICITS ON THE 285K AND 290K ISENTROPIC SURFACES TO LESS THAN 10MB BY APPROXIMATELY 03Z. NAM/GFS SOUNDINGS DIFFER OVERNIGHT...WITH THE NAM NOT NEARLY AS MOIST BELOW 800MB AS THE GFS. WITH ONSHORE FLOW OVER EASTERN UPPER FROM LAKE MICHIGAN WHILE DELTA T/S REMAINING ABOVE 8C DURING THE EVENING...LIKE THE MORE MOIST SCENARIO DEPICTED BY THE GFS...AND WILL KEEP CHANCE POPS ACROSS EASTERN UPPER AFTER 03Z. LOWER LEVELS LOOK TO DRY OVER NORTHERN LOWER FOR PRECIP AT THIS TIME. TEMPERATURES WILL BOTTOM OUT DURING THE EVENING TONIGHT BUT THEN SLOWLY RISE OVERNIGHT WITH THE INCOMING WARM AIR.

MARINE...TIGHTENING PRESSURE GRADIENT COMBINED WITH OVER-LAKE INSTABILITY AND COASTAL CONVERGENCE WILL CREATE WIND SPEEDS AT 925MB TO 40-50KTS TONIGHT AND GALE FORCE WIND GUSTS ALONG THE LAKE MICHIGAN SHORELINE FROM MANISTEE TO THE STRAITS. ELSEWHERE...MIXING TO 925MB REVEALS WIND GUSTS COULD POTENTIALLY REACH BETWEEN 30-35 KNOTS...OR JUST BELOW GALE FORCE...SO WILL INTRODUCE SMALL CRAFTS EVERYWHERE ELSE.

MPC

FOR THE REMAINDER OF THE WEEK...COLD AIR CONTINUES TO MODERATE AND RAPIDLY MOVE EAST OF THE REGION EARLY ON WHILE LOW AMPLITUDE MID LEVEL RIDGING DEVELOPS OVER THE EASTERN STATES...BUT NEXT CORE OF COLD AIR DESCENDS INTO THE NRN ROCKIES. ONE PIECE OF ENERGY (NOW NEAR LAKE WINNIPEG) FORECAST TO MOVE ACROSS SOUTHERN CANADA WITH AN ASSOCIATED LOW PRESSURE SYSTEM AND COLD FRONT SLOWING MOVING THROUGH AND IMPACTING THE REGION THURSDAY THROUGH FRIDAY. MAIN FORECAST ISSUES FOR THE NEAR TERM REVOLVE AROUND PRECIP CHANCES AND TYPE AS THIS SYSTEM PASSES THROUGH.

THURSDAY...AS MENTIONED ABOVE...NRN STREAM SHORTWAVE AND ASSOCIATED SFC LOW FORECAST TO SLOWLY MOVE INTO ONTARIO DURING THE DAY...WITH A WARM FRONT LIFTING THROUGH THE REGION OVERNIGHT/EARLY THURSDAY AND TRAILING COLD FRONT APPROACHING THE REGION BY LATE AFTERNOON. DECENT SHOT OF WARM ADVECTION MAY BE ENOUGH TO PRODUCE BAND OF LIGHT SNOWFALL ACROSS EASTERN UPPER MICHIGAN THURSDAY MORNING AND WILL KEEP A CHANCE GOING IN THE FORECAST FOR THAT AREA...ALTHOUGH LOWER LAYERS ARE A BIT ON THE DRY SIDE. BUT WITHOUT ANY HELP FROM THE LAKES (TEMPS TOO WARM) ANY ACCUMULATIONS SHOULD BE ON THE LIGHT SIDE. THURSDAY AFTERNOON...NORTHERN MICHIGAN WELL INTO THE WARM SECTOR WITH STRONG SW WINDS CONTINUING AND AFTERNOON TEMPS WARMING BACK INTO THE 30S TO AROUND 40 (WOULD BE EVEN WARMER WERE IT NOT FOR THE SNOW COVER). MEANWHILE...BOTH NAM AND PARTICULARLY THE GFS DEPICT SUBSTANTIAL MOISTENING IN THE SUB 800 MB LAYER DURING THE AFTERNOON (WARMER THAN -6C) AHEAD OF THE APPROACHING FRONT...WHILE MOISTURE ALOFT STRIPS OUT. NOT MUCH OUT THERE UPSTREAM TODAY IN TERMS OF LOW CLOUDS TO HANG YOUR HAT ON...BUT CAN SEE THIS TAKING SHAPE AS WARMER/MOIST AIR SURGES NORTH ACROSS THE SNOW COVER IN NORTHERN MICHIGAN. REMOVED MENTION OF ANY RAIN/SNOW FROM THE FORECAST FOR THE AFTERNOON...BUT MAY BE ENOUGH MOISTURE THERE TO GET SOME DRIZZLE GOING ESPECIALLY ACROSS THE HIGHER TERRAIN AREAS.

THURSDAY NIGHT THROUGH FRIDAY...COLD FRONT SLOWLY PRESSES EAST/SE THROUGH THE AREA THURSDAY NIGHT INTO EARLY FRIDAY AND SETTLE TO OUR SOUTH. ALTHOUGH STILL QUITE A BIT OF UNCERTAINLY REGARDING POPS DURING THIS TIMEFRAME...PERHAPS ENOUGH FORCING/MOISTURE ALONG THE FRONT TO SQUEEZE OUT MEASURABLE PRECIP BOTH THURSDAY NIGHT INTO FRIDAY...WITH PRIMARILY SNOW OVER THE NRN TWO-THIRDS OF THE CWA AND RAIN/SNOW OVER THE SOUTH. ALSO...AS COLDER AIR SLOWLY FILTERS INTO THE REGION...SHOULD START TO GET THE LAKES MORE INVOLVED BY FRIDAY. BUT OVERALL ACCUMULATIONS LOOKING TO BE ON THE MINOR SIDE AT THIS POINT.

SATURDAY THRU WEDNESDAY...FRONT CONTINUES TO SAG SOUTH OF THE REGION BY EARLY SATURDAY WITH COLDER AIR ONCE AGAIN SETTLING INTO THE STATE FOR THE WEEKEND. SPLIT FLOW REGIME EMERGES ACROSS THE LOWER 48 STATES BY THE END OF THE WEEK AND HEADING INTO THE WEEKEND...WITH A CLOSED MID LEVEL LOW SLOWLY DROPPING SOUTHWARD ALONG THE WEST COAST INTO THE 4 CORNERS REGION AND LOW AMPLITUDE RIDGING OVER THE EASTERN HALF OF THE CONUS. LATEST MEDIUM RANGE GUIDANCE SUGGESTS BROAD NRN STREAM HIGH PRESSURE WILL SETTLE ACROSS THE NRN PLAINS AND WESTERN GREAT LAKES SATURDAY INTO EARLY SUNDAY WITH TEMPS RUNNING NEAR NORMAL. STILL COLD ENOUGH HOWEVER FOR SOME LIGHT LAKE SNOW SHOWERS DURING THIS TIME ALTHOUGH PROBLEMATIC THIS FAR OUT TO PINPOINT THE EXACT FLOW REGIME AND LOCATIONS WITH THE BEST CHANCES FOR SNOW. BY LATE IN THE WEEKEND AND EARLY NEXT WEEK...SRN STREAM CUTOFF SYSTEM LOOKING TO LIFT THROUGH THE OHIO VALLEY AND INTO NEW ENGLAND. SYSTEM COULD PRODUCE A DECENT AMOUNT OF SNOW (SYSTEM AND LAKE ENHANCED) ACROSS LOWER MICHIGAN IF CURRENT SCENARIO PANS OUT. THEN AGAIN... MEDIUM RANGE SOLUTIONS HAVE SHOWN A GOOD AMOUNT OF UNCERTAINTY WITH REGARD TO LOCATION OF THE STORM TRACK AND TIMING/LOCATION OF DEEPENING WAVES RIDING ALONG THE BAROCLINIC ZONE UP THROUGH THE REGION. BEHIND THIS SYSTEM AS IT STANDS RIGHT NOW...SOME OF THE COLDEST AIR OF THE YEAR GETS PULLED INTO NRN MICHIGAN FOR TUESDAY AND WEDNESDAY...WHILE STRONG HIGH PRESSURE BUILDS INTO THE PLAINS AND WESTERN GREAT LAKES. HOWEVER...WITH THE COLD AIR IN PLACE WILL HAVE CONTINUING CHANCES FOR SNOW SHOWERS.

ADAM

&&

.APX...WATCHES/WARNINGS/ADVISORIES...GALE WARNING...TONIGHT THROUGH THURSDAY....LMZ323-342-344-345.

&&

$$

.UPDATE...

LES IS WINDING DOWN STEADILY THIS MORNING AS HIGH PRES RIDGE MOVES ACROSS THE AREA. RIDGE CURRENTLY RUNS FROM LAKE MICHIGAN TO CNTRL LAKE SUPERIOR. UPSTREAM...VIGOROUS SHORTWAVE HEADING INTO SRN SASKATCHEWAN IS LEADING TO STRONG WAA PATTERN OVER THE NRN PLAINS. 12Z SOUNDING AT KBIS SHOWED 850MB TEMP OF 7C WITH SW WIND AT 35KT WHILE KINL/CYQD HAD 850MB TEMPS OF -11/-19C RESPECTIVELY. WAA/ISENTROPIC ASCENT REGIME HAS RESULTED IN MID CLOUD DECK FROM THE DAKOTAS ACROSS NRN MN. RADARS SHOW RETURNS FROM CLOUD DECK...BUT ONLY A FEW OBS HAVE SHOWN ANY SNOW IN NRN MN AS DRY AIRMASS PER 12Z KINL SOUNDING HAS KEPT MUCH OF THE SNOW FROM REACHING THE GROUND.

LAST OF THE LES SHOULD END OVER THE FAR NE FCST AREA DURING THE NEXT FEW HRS AS WINDS BACK OFFSHORE WITH PASSAGE OF RIDGE AXIS. STRONG WAA REGIME WILL THEN BEGIN TO SPREAD E INTO WRN UPPER MI DURING THE AFTN...BUT EXPECT DRY AIR TO DELAY ONSET OF -SN SIGNIFICANTLY. RECENT TAMDAR SOUNDING FROM KSAW SHOWED DWPT DEPRESSIONS FROM 10 TO 25C BTWN 900 AND 700MB. INHERITED FCST LOOKED FINE JUST BRINGING CHC -SN TO WRN LAKE SUPERIOR DURING THE AFTN.

&&

.PREV DISCUSSION... ISSUED AT 335 AM EST

00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW TROF OVER ERN NAMERICA DOWNSTREAM OF UPR RDG BLDG INTO THE NRN PLAINS IN ADVANCE OF POTENT SHRTWV CRASHING INTO THE PAC NW (12Z-24Z H3 HGT FALL UP TO 250M IN NW WA STATE). CWA EARLY THIS MRNG REMAINS DOMINATED BY COLD AND GUSTY LLVL NW FLOW BTWN SFC HI PRES RDG APRCHG THE MS RIVER VALLEY AND DEEP LO PRES OVER QUEBEC. H85 TEMPS UPSTREAM STILL AS LO AS -21C AT YPL. ALTHOUGH LLVLS AT THIS SITE ARE RELATIVELY MOIST...ABSOLUTE MSTR IS LIMITED WITH SFC DWPTS BLO 0F IN MN AND ONTARIO NW OF LK SUP. 00Z INL SDNG IS QUITE A BIT DRIER THAN THE YPL SDNG CLOSER TO RDG AXIS...AND SKIES ARE MOCLR NOW IN THE MN ARROWHEAD. DESPITE THE VIGOROUS CAD OVER THE UPR LKS...THE COMBINATION OF THIS DRY AIR AND LO INVRN ARND H9 AS SHOWN ON THE 00Z INL/YPL RAOBS AS WELL AS TAMDAR SDNGS AT DLH/YQT HAVE NEGATIVELY IMPACTED LES AMTS EVEN OVER THE ERN ZNS WHERE LONGER FETCH ACRS THE LK HAS ALLOWED MORE LLVL MOISTENING AND DEEPER MIXED LYR UP TO H8 AS SHOWN ON THE 00Z TAMDAR SDNG FM SAW. NO MORE THAN 3-4 INCHES OF SN HAS FALLEN THRU 04Z. FARTHER UPSTREAM...MID/HI CLD IN WAD AHEAD OF SHRTWV MOVING INTO THE PAC NW HAS SPREAD THRU THE UPR RDG INTO NW MN. 00Z BIS SDNG IS QUITE DRY BLO H8...SO LEADING EDGE OF LGT SN TRAILS WELL BEHIND IN SE SASKATCHEWAN AT 04Z.

MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND LES TRENDS. FOCUS THEN SHIFTS TO TIMING/IMPACT OF SHRTWV NOW MOVING INTO THE PAC NW WITH CHC OF -SN AS EARLY AS THIS AFTN.

FOR TDAY...NUMERICAL GUIDANCE SHOWS H5 HGT RISES UP TO 120M AS RDG IN THE PLAINS CONTINUES TO BLD EWD. SFC RDG AXIS PROGGED TO REACH NR IWD AT 12Z BEFORE PUSHING E OF ANJ BY 00Z THU. AS THE RDG AXIS/LOWER INVRN HGT APRCH FM THE W...EXPECT ONGOING LES TO END AND WINDS TO DIMINISH W-E. HAVE OPTED TO EXTEND THE LES ADVY (WITHOUT THE BLSN) OVER THE E A FEW HRS TO ACCOUNT FOR FVRBL CONDITIONS FOR MORE SHSN INTO MID MRNG. OTRW...BRIEF CLRG WL GIVE WAY TO INCRSG HI/MID CLD WITH ONSET OF ISENTROPIC ASCENT AS SHOWN ON THE 280-300K SFCS. SINCE LLVLS ON THE BIS SDNG ARE SO DRY AND ISENTROPIC ASCENT APPEARS TO BE THE ONLY FORCING MECHANISM FOR UPWARD MOTION WITH DPVA/UPR DVGC ASSOCIATED WITH SHRTWV NOW MOVING INTO THE PAC NW REMAINING TO THE NW THRU 00Z (SHRTWV ITSELF FCST TO REACH SE SASKATCHEWAN AT 00Z)... HAVE OPTED TO TAKE OUT THE WAD POPS TDAY OVER THE ENTIRE CWA PER VARIOUS MOS FCSTS. RESOLVE STRENGTHENED BECAUSE ISENTROPIC LIFT APPEARS TO BE GOING MORE TOWARD HORIZONTAL TEMP ADVCTN VS UVV AS PRES FCST TO RISE STEADILY ON THE ISENTROPIC SFCS IN QUESTION (I.E. STEADY WARMING)...NOT SURPRISING CONSIDERING TRACK OF SHRTWV WELL TO THE NW. OTRW...VARIOUS MOS FCST HI TEMPS CONSISTENT WITH READINGS EXPECTED FM EXPLICIT GFS FCST SDNGS.

TNGT...SHRTWV OVER SRN CANADA FCST TO MOVE INTO NW ONTARIO BY 12Z THU. THERE IS SOME DISCREPANCY WITH REGARD TO THE POSITION OF SFC LO BY 12Z...WITH NAM FARTHEST TO THE NW JUST E OF LK WINNIPEG AND UKMET FARTHEST TO THE S NR DLH. 00Z GFS/12Z ECMWF LOOK TO BE A RSNBL COMPROMISE BTWN THESE SOLNS WITH SFC LO JUST N OF INL. GFS SHOWS BEST ISENTROPIC LIFT AS WELL AS DPVA/SHARPER H85-5 QVECTOR CNVGC/UPR DVGC TO THE N. CONSIDERING THE PLACEMENT OF THESE BETTER DYNAMICS AND LINGERING DRY AIR...HAVE OPTED TO RESTRICT CHC POPS TO OVER THE NRN TIER AND DOWNWIND OF LK MI WHERE STRONG SLY FLOW WL BE ABLE TO PICK UP SOME MSTR IN LONG FETCH OVER LK. IN FACT...GFS FCST SDNG FOR ERY AT 06Z SHOWS RELATIVELY DEEP MSTR...SO HIEST CHC POPS IN THIS LOCATION. OTRW...EXPECT RELATIVELY LTL DIURNAL VARIATION OF TEMP WITH STRG SLY FLOW...GFS SHOWS H925 WINDS UP TO 35-40 KTS. WL ISSUE GALE WRNG FOR LK SUP AS THIS LLJ MOVES OVHD TO THE S OF AREA OF SHARP PRES FALLS MOVING ACRS ONTARIO.

ON THU...SHRTWV/SFC LO FCST TO SHEAR TO THE ENE...DRAGGING SFC COLD FNT TO THE E AND SCNTRL ZNS BY LATE IN THE DAY. ALTHOUGH SOME LLVL MSTR REMAINS...DRYING ALF IN JET SURGE REGION UNDER H85-5 QVECTOR DVGC SUGS ANY PCPN WL BE ON THE LGT SIDE. TEMPTED TO RESTRICT POPS TO JUST THE N AND E DURING THE MRNG BEFORE DEEPER MSTR EXITS... BUT 00Z GFS HINTS SOME UPR DVGC IN RRQ OF JET PASSING TO THE NE WL CAUSE AN AXIS OF HIER H7 RH OVER THE FNT LATER IN THE DAY OVER THE SCNTRL AND E. SINCE SEVERAL OTHER OPS MODELS ARE SLOWER PUSHING THE FNT THROUGH UNDER SW FLOW ALF PARALLEL TO SFC BNDRY...WL RETAIN AT LEAST A 20 POP OVER THE ENTIRE FA. WL ALSO INCLUDE MIX WITH RA OVER THE SCNTRL AS SFC TEMPS WL RISE WELL ABV 32 AND FCST SNDGS HINT AT SUFFICIENT DEPTH OF ABV FRZG NR SFC LYR TO JUSTIFY LIQUID PCPN. WITH RELATIVELY WARM START...THU LOOKS TO BE THE WARMEST DAY OF THE WEEK EVEN THOUGH CONSIDERABLE CLD COVER WL RESTRICT DIURNAL TEMP RISE.

COLDER AIR FCST TO GRDLY FILTER BACK INTO UPR MI THU NGT/FRI AS UPR FLOW GRDLY VEERS FM SW TO MORE W WITH TIME. BUT GFS/UKMET HINT THAT RRQ OF UPR JET IN CONFLUENCE ZN BTWN NRN AND SRN BRANCHES WL REMAIN OVER THE FA WITH A POCKET OF HIER H7 RH NEAR FOCUSED H8-7 FGEN WELL TO THE N OF RELATIVELY SHALLOW ARCTIC INTRUSION. ALTHOUGH NLY FLOW OF ARCTIC AIR APPEARS TO BE RATHER DRY...WL MAINTAIN SOME CHC POPS DURING THIS TIME FOR EITHER THE FGEN FORCING OR LES POTENTIAL. CONSIDERING THE FAIRLY HI STABILITY AND SHARP H8-7 FGEN...HAVE TRENDED DOWN ON FCST TEMPS THU NGT/FRI PER GFS FCST SDNGS AND GFS/ETA MOS GUIDANCE.

MUCH UNCERTAINTY REMAINS IN THE LATER PDS AS TO INTERACTION BTWN NRN BRANCH AND SRN BRANCH CLOSED LO OVER THE DESERT SW. LATEST GUIDANCE HAS TRENDED A BIT SLOWER WITH EJECTION OF THIS FEATURE...SO ADDED LO CHC POPS OVER THE SCNTRL ZNS ON SUN NGT/MON TO MATCH SURROUNDING OFFICES.

COORDINATED WITH APX/GRB/DLH.

&&

.MQT WATCHES/WARNINGS/ADVISORIES... GALE WARNING E HALF OF LAKE SUPERIOR. &&

$$

ROLFSON (UPDATE) KC (PREV DISCUSSION)

.DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW TROF OVER ERN NAMERICA DOWNSTREAM OF UPR RDG BLDG INTO THE NRN PLAINS IN ADVANCE OF POTENT SHRTWV CRASHING INTO THE PAC NW (12Z-24Z H3 HGT FALL UP TO 250M IN NW WA STATE). CWA EARLY THIS MRNG REMAINS DOMINATED BY COLD AND GUSTY LLVL NW FLOW BTWN SFC HI PRES RDG APRCHG THE MS RIVER VALLEY AND DEEP LO PRES OVER QUEBEC. H85 TEMPS UPSTREAM STILL AS LO AS -21C AT YPL. ALTHOUGH LLVLS AT THIS SITE ARE RELATIVELY MOIST...ABSOLUTE MSTR IS LIMITED WITH SFC DWPTS BLO 0F IN MN AND ONTARIO NW OF LK SUP. 00Z INL SDNG IS QUITE A BIT DRIER THAN THE YPL SDNG CLOSER TO RDG AXIS...AND SKIES ARE MOCLR NOW IN THE MN ARROWHEAD. DESPITE THE VIGOROUS CAD OVER THE UPR LKS...THE COMBINATION OF THIS DRY AIR AND LO INVRN ARND H9 AS SHOWN ON THE 00Z INL/YPL RAOBS AS WELL AS TAMDAR SDNGS AT DLH/YQT HAVE NEGATIVELY IMPACTED LES AMTS EVEN OVER THE ERN ZNS WHERE LONGER FETCH ACRS THE LK HAS ALLOWED MORE LLVL MOISTENING AND DEEPER MIXED LYR UP TO H8 AS SHOWN ON THE 00Z TAMDAR SDNG FM SAW. NO MORE THAN 3-4 INCHES OF SN HAS FALLEN THRU 04Z. FARTHER UPSTREAM...MID/HI CLD IN WAD AHEAD OF SHRTWV MOVING INTO THE PAC NW HAS SPREAD THRU THE UPR RDG INTO NW MN. 00Z BIS SDNG IS QUITE DRY BLO H8...SO LEADING EDGE OF LGT SN TRAILS WELL BEHIND IN SE SASKATCHEWAN AT 04Z.

MAIN FCST CONCERNS IN THE SHORT TERM REVOLVE ARND LES TRENDS. FOCUS THEN SHIFTS TO TIMING/IMPACT OF SHRTWV NOW MOVING INTO THE PAC NW WITH CHC OF -SN AS EARLY AS THIS AFTN.

FOR TDAY...NUMERICAL GUIDANCE SHOWS H5 HGT RISES UP TO 120M AS RDG IN THE PLAINS CONTINUES TO BLD EWD. SFC RDG AXIS PROGGED TO REACH NR IWD AT 12Z BEFORE PUSHING E OF ANJ BY 00Z THU. AS THE RDG AXIS/LOWER INVRN HGT APRCH FM THE W...EXPECT ONGOING LES TO END AND WINDS TO DIMINISH W-E. HAVE OPTED TO EXTEND THE LES ADVY (WITHOUT THE BLSN) OVER THE E A FEW HRS TO ACCOUNT FOR FVRBL CONDITIONS FOR MORE SHSN INTO MID MRNG. OTRW...BRIEF CLRG WL GIVE WAY TO INCRSG HI/MID CLD WITH ONSET OF ISENTROPIC ASCENT AS SHOWN ON THE 280-300K SFCS. SINCE LLVLS ON THE BIS SDNG ARE SO DRY AND ISENTROPIC ASCENT APPEARS TO BE THE ONLY FORCING MECHANISM FOR UPWARD MOTION WITH DPVA/UPR DVGC ASSOCIATED WITH SHRTWV NOW MOVING INTO THE PAC NW REMAINING TO THE NW THRU 00Z (SHRTWV ITSELF FCST TO REACH SE SASKATCHEWAN AT 00Z)... HAVE OPTED TO TAKE OUT THE WAD POPS TDAY OVER THE ENTIRE CWA PER VARIOUS MOS FCSTS. RESOLVE STRENGTHENED BECAUSE ISENTROPIC LIFT APPEARS TO BE GOING MORE TOWARD HORIZONTAL TEMP ADVCTN VS UVV AS PRES FCST TO RISE STEADILY ON THE ISENTROPIC SFCS IN QUESTION (I.E. STEADY WARMING)...NOT SURPRISING CONSIDERING TRACK OF SHRTWV WELL TO THE NW. OTRW...VARIOUS MOS FCST HI TEMPS CONSISTENT WITH READINGS EXPECTED FM EXPLICIT GFS FCST SDNGS.

TNGT...SHRTWV OVER SRN CANADA FCST TO MOVE INTO NW ONTARIO BY 12Z THU. THERE IS SOME DISCREPANCY WITH REGARD TO THE POSITION OF SFC LO BY 12Z...WITH NAM FARTHEST TO THE NW JUST E OF LK WINNIPEG AND UKMET FARTHEST TO THE S NR DLH. 00Z GFS/12Z ECMWF LOOK TO BE A RSNBL COMPROMISE BTWN THESE SOLNS WITH SFC LO JUST N OF INL. GFS SHOWS BEST ISENTROPIC LIFT AS WELL AS DPVA/SHARPER H85-5 QVECTOR CNVGC/UPR DVGC TO THE N. CONSIDERING THE PLACEMENT OF THESE BETTER DYNAMICS AND LINGERING DRY AIR...HAVE OPTED TO RESTRICT CHC POPS TO OVER THE NRN TIER AND DOWNWIND OF LK MI WHERE STRONG SLY FLOW WL BE ABLE TO PICK UP SOME MSTR IN LONG FETCH OVER LK. IN FACT...GFS FCST SDNG FOR ERY AT 06Z SHOWS RELATIVELY DEEP MSTR...SO HIEST CHC POPS IN THIS LOCATION. OTRW...EXPECT RELATIVELY LTL DIURNAL VARIATION OF TEMP WITH STRG SLY FLOW...GFS SHOWS H925 WINDS UP TO 35-40 KTS. WL ISSUE GALE WRNG FOR LK SUP AS THIS LLJ MOVES OVHD TO THE S OF AREA OF SHARP PRES FALLS MOVING ACRS ONTARIO.

ON THU...SHRTWV/SFC LO FCST TO SHEAR TO THE ENE...DRAGGING SFC COLD FNT TO THE E AND SCNTRL ZNS BY LATE IN THE DAY. ALTHOUGH SOME LLVL MSTR REMAINS...DRYING ALF IN JET SURGE REGION UNDER H85-5 QVECTOR DVGC SUGS ANY PCPN WL BE ON THE LGT SIDE. TEMPTED TO RESTRICT POPS TO JUST THE N AND E DURING THE MRNG BEFORE DEEPER MSTR EXITS... BUT 00Z GFS HINTS SOME UPR DVGC IN RRQ OF JET PASSING TO THE NE WL CAUSE AN AXIS OF HIER H7 RH OVER THE FNT LATER IN THE DAY OVER THE SCNTRL AND E. SINCE SEVERAL OTHER OPS MODELS ARE SLOWER PUSHING THE FNT THROUGH UNDER SW FLOW ALF PARALLEL TO SFC BNDRY...WL RETAIN AT LEAST A 20 POP OVER THE ENTIRE FA. WL ALSO INCLUDE MIX WITH RA OVER THE SCNTRL AS SFC TEMPS WL RISE WELL ABV 32 AND FCST SNDGS HINT AT SUFFICIENT DEPTH OF ABV FRZG NR SFC LYR TO JUSTIFY LIQUID PCPN. WITH RELATIVELY WARM START...THU LOOKS TO BE THE WARMEST DAY OF THE WEEK EVEN THOUGH CONSIDERABLE CLD COVER WL RESTRICT DIURNAL TEMP RISE.

COLDER AIR FCST TO GRDLY FILTER BACK INTO UPR MI THU NGT/FRI AS UPR FLOW GRDLY VEERS FM SW TO MORE W WITH TIME. BUT GFS/UKMET HINT THAT RRQ OF UPR JET IN CONFLUENCE ZN BTWN NRN AND SRN BRANCHES WL REMAIN OVER THE FA WITH A POCKET OF HIER H7 RH NEAR FOCUSED H8-7 FGEN WELL TO THE N OF RELATIVELY SHALLOW ARCTIC INTRUSION. ALTHOUGH NLY FLOW OF ARCTIC AIR APPEARS TO BE RATHER DRY...WL MAINTAIN SOME CHC POPS DURING THIS TIME FOR EITHER THE FGEN FORCING OR LES POTENTIAL. CONSIDERING THE FAIRLY HI STABILITY AND SHARP H8-7 FGEN...HAVE TRENDED DOWN ON FCST TEMPS THU NGT/FRI PER GFS FCST SDNGS AND GFS/ETA MOS GUIDANCE.

MUCH UNCERTAINTY REMAINS IN THE LATER PDS AS TO INTERACTION BTWN NRN BRANCH AND SRN BRANCH CLOSED LO OVER THE DESERT SW. LATEST GUIDANCE HAS TRENDED A BIT SLOWER WITH EJECTION OF THIS FEATURE...SO ADDED LO CHC POPS OVER THE SCNTRL ZNS ON SUN NGT/MON TO MATCH SURROUNDING OFFICES.

COORDINATED WITH APX/GRB/DLH.

&&

.MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVY UNTIL 15Z WED MIZ006-007-085. GALE WRNG E 1/2 LK SUP. &&

$$ KC

.SHORT TERM (TODAY AND TONIGHT)...

EARLY MORNING ACARS SOUNDINGS FROM SDF INDICATED THE ATMOSPHERE WAS STILL FAIRLY DRY BELOW 700MB. SURFACE DEPRESSIONS AT 07Z WERE ALSO AROUND 20 DEGREES. WE WILL NEED TO SATURATE THIS LAYER BEFORE SIGNIFICANT RAIN BEGINS TO FALL.

IN THE UPPER LEVELS OF THE ATMOSPHERE A WEST COAST TROUGH WILL CONTINUE TO DEEPEN WITH RIDGING ACROSS THE EASTERN UNITED STATES. A 100KT JET WILL DEVELOP JUST TO THE NORTH OF THE REGION LATE IN THE DAY AND WILL AID IN PRECIPITATION GENERATION OVERNIGHT. AT THE SURFACE A VERY WELL DEFINED COLD FRONT EXTENDED FROM SOUTHEAST KANSAS TO NORTHWEST ILLINOIS AT 06Z. TEMPERATURES ACROSS THE FRONT WERE 15 TO 20 DEGREES WITH VERY COLD AIR IN THE TEENS NOTED IN IOWA.

NOT MUCH TO GET A HANDLE ON THIS MORNING WITH LACK OF LIFT WE EXPECT MAINLY AREAS OF LIGHT TO OCCASIONALLY MODERATE RAIN ACROSS THE FORECAST AREA. THE BEST CHANCE FOR HEAVY RAIN WILL OCCUR TONIGHT AND MAINLY ACROSS SOUTHERN INDIANA. THE LIFT FROM THE FORE MENTIONED JET COMBINED WITH A DEVELOPING WAVE ALONG THE COLD FRONT WILL BRING HEAVY RAIN TO THE REGION BETWEEN 06Z AND 12Z SATURDAY. WIDESPREAD 1 INCH AMOUNTS WILL BE COMMON ACROSS SOUTHERN INDIANA WITH LESSER AMOUNTS ACROSS CENTRAL KENTUCKY.

WITH THE MOIST SOUTHERLY FLOW IN PLACE WE WILL NOT SEE MUCH DIURNAL TEMPERATURE CHANCE THROUGH THE PERIOD WITH TEMPERATURES REMAINING IN THE 50S. --JA

LONG TERM (SATURDAY THROUGH THURSDAY)...

OCCASIONAL RAIN FROM SATURDAY THROUGH EARLY MONDAY WILL LEAD TO SUBSTANTIAL RAINFALL TOTALS AND A THREAT OF FLOODING EARLY NEXT WEEK.

UPPER AIR PATTERN WILL FEATURE A SHEARED POSITIVELY TILTED TROUGH WHOSE CENTER WILL ONLY SLOWLY MOVE FROM NEVADA TO COLORADO THROUGH LATE SUNDAY. STRONG SOUTHWESTERLY MID LEVEL FLOW WILL CONTINUE ACROSS THE MID PART OF THE COUNTRY AND WILL EFFICIENTLY TRANSPORT MOISTURE TOWARDS THE LOWER MISSOURI AND OHIO VALLEYS. ARCTIC HIGH PRESSURE ACROSS THE NORTHERN PLAINS WILL HELP PUSH A SHALLOW COLD FRONT TOWARDS THE OHIO RIVER EARLY SATURDAY. THIS FRONT WILL SERVE AS A FOCUS FOR REPEATED EPISODES OF RAIN AS IT SLOWLY MOVE TOWARDS CENTRAL KENTUCKY...AND THEN STALLS SUNDAY.

TIMING INDIVIDUAL DISTURBANCES AND CORRESPONDING PERIODS OF HEAVIER RAIN WILL BE CHALLENGING AS THE UPPER FLOW WILL BE BROAD...AND NO OBVIOUS DISTURBANCES WILL MOVE NORTHEAST THROUGH THE FLOW UNTIL THE UPPER TROUGH EJECTS INTO THE PLAINS LATE SUNDAY.

THE NAM MODEL HINTS AT WEAK LOW PRESSURE MOVING JUST NORTH OF THE OHIO RIVER EARLY SATURDAY ALONG A SURFACE BOUNDARY. BOTH GFS AND NAM FORECAST HIGHER RAINFALL AMOUNTS DEVELOPING ACROSS SOUTHERN INDIANA FRIDAY NIGHT AND SAGGING SOUTHEAST INTO CENTRAL KENTUCKY BY LATE SATURDAY.

ANOTHER PERIOD OF MODERATE TO OCCASIONALLY HEAVY RAIN IS FORECAST TO DEVELOP LATE SUNDAY AND CONTINUE THROUGH MID DAY MONDAY AS THE UPPER TROUGH ACROSS THE SOUTHERN PLAINS OPENS UP AND MOVES TOWARDS IOWA. LOW PRESSURE WILL DEVELOP ALONG THE BY NOW STATIONARY FRONT AND MOVE ACROSS CENTRAL OR NORTHERN KENTUCKY DURING THE EARLY MORNING HOURS MONDAY. THE AXIS OF HEAVY RAIN IS EXPECTED TO DEVELOP RIGHT ALONG THE BOUNDARY AND THE EVENTUAL PATH OF THE SURFACE LOW.

THE GFS IS MUCH WETTER IN QPF AMOUNTS THEN THE NAM AND WILL FORECAST AN AMOUNT IN BETWEEN THE TWO. FOR THE ENTIRE WEEKEND PERIOD INTO MONDAY...STILL FEEL THAT 2 TO 4 INCHES WITH LOCALLY HIGHER AMOUNTS ARE LIKELY...WITH THE BULK OF THIS FALLING LATE SUNDAY INTO MONDAY. WILL CONTINUE FLOOD WATCH FROM LATE FRIDAY THROUGH EARLY MONDAY.

TEMPERATURES WILL BE A CHALLENGE BOTH SATURDAY AFTERNOON AND SUNDAY. THE NAM IS SIMILAR TO YESTERDAY WITH BEING ONCE AGAIN LESS AGGRESSIVE WITH THE SOUTHEASTWARD PUSH OF THE FRONT...STALLING IT OUT JUST SOUTH OF THE OHIO RIVER EARLY SUNDAY. THE GFS PUSHES THE FRONT FARTHER SOUTH INTO NORTHWESTERN TENNESSEE BY THIS SAME TIME. THIS BOUNDARY MAY KEEP TEMPERATURES ACROSS SOUTHERN INDIANA IN THE MID 40S SUNDAY...WHILE 60 MAY BE APPROACHED ALONG OUR SOUTHERN COUNTIES.

MONDAY THROUGH TUESDAY...

SURFACE LOW WILL RAPIDLY MOVE OFF TO OUR EAST MONDAY AND DEEP LAYER MOISTURE WILL MOVE SOUTH ALONG SURFACE BOUNDARY INTO THE TENNESSEE VALLEY. AS HIGH PRESSURE BUILDS ACROSS THE UPPER MIDWEST...COLDER AIR WILL FILTER ACROSS OUR AREA MONDAY AND TUESDAY. THIS WILL KNOCK OUR TEMPERATURES DOWN TO SEASONABLE LEVELS. FORECAST SOUNDINGS SHOW AMPLE LOW LEVEL MOISTURE LINGERING SEVERAL HUNDRED MILES NORTH OF THE COLD FRONT...SO EXPECT CLOUDY SKIES TO CONTINUE PROBABLY INTO EARLY TUESDAY.

TUESDAY NIGHT THROUGH THURSDAY...

HIGH PRESSURE WILL BUILD INTO THE AREA TUESDAY AND KEEP DRY BUT COLD WEATHER OVER THE LOWER OHIO VALLEY THROUGH THURSDAY.

JSD

&&

.LMK WATCHES/WARNINGS/ADVISORIES... KY...FLOOD WATCH FROM FRIDAY EVENING THROUGH LATE SUNDAY NIGHT FOR KYZ023>043-045>049-053>057-061>067-070>078-081-082.

IN...FLOOD WATCH FROM FRIDAY EVENING THROUGH LATE SUNDAY NIGHT FOR INZ076>079-083-084-089>092.

&&

FRONTAL BOUNDARY ACROSS THE CENTRAL CONUS WILL SHARPEN UP AS THE ROCKIES POSITIVELY TILTED TROUGH AXIS EASES EAST. THIS WILL SET UP A CORRIDOR OF PRECIPITATION AS COPIOUS MOIST INFLUX FROM THE WESTERN GULF OVERRUNS THE BOUNDARY ACROSS THE PLAINS. SOUTHWESTERLY DEEP LAYER FLOW WILL AID IN PRECIPITATION DEVELOPING NORTHEAST THROUGH THE OHIO VALLEY AND EASTERN GREAT LAKES. THIS IS AN ANNAFRONTAL SYNOPTIC SETUP...WITH MUCH OF THE PRECIPITATION ALONG AND BEHIND THE BOUNDARY. THEREFORE...NOT EXPECTING MUCH MORE THAN A FEW LIGHT RAIN SHOWERS DURING THE SHORT TERM WITHIN THE WARM SECTOR.

WITH EXTENSIVE CLOUD COVER...THOUGHT MOS HIGHS MAY HAVE BEEN A FEW DEGREES TOO OPTIMISTIC. SIMILARLY...THEY MAY BE TOO COOL TONIGHT. LOW TEMPERATURES MAY NEED TO BE NUDGED EVEN HIGHER. PRESSURE GRADIENT ON THE BACKSIDE OF THE SURFACE HIGH WILL SUPPORT SOUTHWEST FLOW THROUGH THE SHORT TERM PERIOD.

&&

.AVIATION... CONTINUED WARM ADVECTION WILL ALLOW CLOUDS TO BUILD DOWN THROUGH THE TAF CYCLE. EXPECT WARM ADVECTION PRECIPITATION CLIPPING THE WEST VIRGINIA PAN HANDLE TO BE IT THIS MORNING...WITH REMAINING PRECIPITATION LARGELY ALONG AND BEHIND THE OHIO VALLEY FRONTAL BOUNDARY THROUGH TONIGHT.

&&

.MARINE... 00Z ETA MOS AT THOMAS POINT SUGGESTS 16KT SUSTAINED TODAY...AND 10KT TONIGHT...WHILE THE 00Z GFS MOS SHOWS 10KT THROUGH THE SHORT TERM. 00Z NAM PROXIMITY LAND BUFKIT FORECAST SOUNDINGS SUGGEST ADDITIONAL WIND GUST MOMENTUM OF UP TO 20 KNOTS POSSIBLE NEAR THE VIRGINIA STATE LINE AND ALONG THE POTOMAC TODAY...WHILE THE 00Z GFS ALSO INDICATES 20KT WIND GUSTS NEAR THE VIRGINIA WATERS. WILL THEREFORE HAVE A SMALL CRAFT ADVISORY ACROSS THE POTOMAC/BAY MARINE ZONES CLOSEST TO THE VIRGINIA STATE LINE.

POSITIONING OF BNDRY ON SUN WILL CONTROL THE THREAT OF STRONGER WINDS OVER THE MARINE AREA AS PRES GRAD SHOULD REALLY GET GOING BY SUNDAY NIGHT AS LOW PRES MOVES FROM THE OH VLY. THINK BEST CHC WILL BE ON MONDAY ACROSS THE SOUTHERN MARINE ZONES FOR SCA WINDS...THEN ALL ZONES ON TUESDAY ONCE NW FLOW KICKS UP.

&&

.TIDES... WATER LEVELS ARE CURRENTLY A FOOT ABOVE ASTRONOMIC PREDICTIONS. THE LUNAR CYCLE IS WANING (43% FULL). A LONG DURATION SOUTHWEST FLOW WILL CONTINUE AHEAD OF A SLOW MOVING COLD FRONT. THIS WILL PROMOTE RISING WATER LEVELS WHICH NEED TO BE MONITORED SHOULD THEY BEGIN TO NEAR MINOR COASTAL FLOOD CRITERIA.

THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM HAS SLIGHTLY UNDER-PREDICTED WATER LEVELS THUS FAR...AND MAINTAINS CURRENT DEPARTURES THROUGH THE AFTERNOON. THE NOAA EXTRATROPICAL STORM SURGE MODEL DID NOT THE CAPTURE DEPARTURE RISES.

&&

.LONG TERM...SATURDAY THROUGH THURSDAY...

BNDRY WILL SETTLE ACROSS OUR FORECAST AREA BETWEEN SATURDAY AND SUNDAY AND HELP TO FEED WAVES OF SHOWERS ACROSS THE REGION. MOS POPS VARY QUITE A BIT BETWEEN NW AND SE ZONES BUT HAVE INDICATE LESS EXTREME DELINEATIONS SINCE EXACT FRONTAL PLACEMENT AND SUBSEQUENT PRECIP AREAS STILL A LITTLE DIFFICULT TO PINPOINT. BOTH DAYS WILL HAVE 50-70 POPS ACROSS THE AREA. ONLY MIDDLE RANGE CHC POPS FOR SAT NGT THOUGH AS THERE SHOULD BE A BRIEF RESPITE FROM THE WEAK LOW PRES WAVE ACTION ALONG THE BNDRY. SUN NGT AND MON WILL CONTINUE TO INDICATE FAIRLY GOOD CHCS FOR RAINFALL AS ADDITIONAL LOW PRES WAVES FORM ALONG THE FRONT...AND THE FRONT BEGINS TO KICK THROUGH ON MONDAY OR MONDAY EVNG WITH A REALLY DECENT PUSH OF ARCTIC FROM ACROSS THE OHIO VALLEY.

DURING THE TUESDAY THROUGH THURSDAY TIMEFRAME...COLD AIRMASS SETTLES OVER OUR REGION ALTHOUGH THERE PROBABLY WON`T BE ANY DECENT PRECIP MAKERS SAVE FOR A FEW SNOW SHOWERS IN THE HIGHER TERRAIN GIVEN THE COLD NW FLOW AND SOME U/L VORT ENERGY. BEST CHC OF COURSE LATE MON NGT AND TUESDAY ACROSS THE ALLEGHENY FRONT WHEN SOME DECENT UPSLOPE SNOW SHWRS COULD TAKE PLACE. TEMPS NEAR OR SLIGHTLY BELOW NORMAL TUE-THU WITH HIGHS IN THE 30S AND LOWS IN THE TEENS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR ANZ530-531.

SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ532>534.

SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ537.

&&

$$

SHORT TERM/HYDROLOGY/AVIATION/TIDES...ROGOWSKI LONG TERM...BROTHERTON MARINE...ROGOWSKI/BROTHERTON

.SYNOPSIS...A COLD UPPER LEVEL TROUGH AND LOW PRESSURE SYSTEM WILL MOVE OVER SOUTHERN CALIFORNIA TODAY. SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS ARE POSSIBLE THROUGH THE AFTERNOON. THE TROUGH WILL MOVE EAST TONIGHT. GUSTY WINDS MAINLY IN THE MOUNTAINS AND DESERTS WILL DECREASE THIS EVENING. IT WILL BE VERY COLD AT NIGHT AND IN THE EARLY MORNING FOR THE NEXT FEW DAYS. AN OFFSHORE FLOW WILL DEVELOP LATE TONIGHT AND INCREASE SATURDAY MORNING WITH GUSTY NORTHEAST WINDS MAINLY INLAND AND IN THE MOUNTAINS. THE OFFSHORE FLOW WILL CONTINUE THROUGH THURSDAY.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

BUSY MORNING WITH SHORT TERM WEATHER CONCERNS. BACK EDGE OF THIS IMPULSE SHOULD BE EAST OF FORECAST AREA BY 1200 PST. MAIN TROUGH AXIS REMAINS OVER SOUTHWEST CALIFORNIA THROUGH TONIGHT....THEN MOVES EAST SATURDAY AFTERNOON. THIS RAISES CONCERN ABOUT WRAP AROUND MOISTURE/UPSLOPE CONDITIONS ON NORTH SLOPES OF SAN BERNARDINO MOUNTAINS AND WEST AND NORTHWEST FACING SLOPES OF REMAINING MOUNTAINS AS WELL AS CONVERGENCE AROUND ISLANDS AND INSTABILITY OVER WATER TONIGHT GENERATING CONVECTION OVER WATER THAT MOVES ACROSS COASTAL AREAS AND SAN DIEGO COUNTY INLAND VALLEYS. MAY BE UPPING POPS IN THIS AFTERNOON PACKAGE...THOUGH PRECIPITATION AMOUNTS WILL BE VERY LIGHT...SNOW FLURRIES FOR MOUNTAINS AND ICE PELLETS LOWER ELEVATIONS. A COUPLE OF OTHER CHANGES ANTICIPATED TO TONIGHT/SATURDAY MORNING FORECAST...WIND CHILL AND FREEZING TEMPERATURES. WIND SPEEDS/TEMPERATURES CURRENTLY IN FORECAST GENERATE WIND CHILL VALUES BETWEEN -12 AND -25 DEGREES OVER SAN BERNARDINO MOUNTAINS BETWEEN 4 PM AND 10 AM SATURDAY. MAY MAKE SOME ADDITIONAL ADJUSTMENTS TO WIND GRIDS FOR SATURDAY MORNING WHICH MIGHT SHORTEN THIS TIME SPAN. WIDESPREAD TEMPERATURES BELOW FREEZING ACROSS VALLEYS/DESERTS/AND COASTAL AREAS 1 AM TO 9 AM SATURDAY MORNING. STILL SORTING OUT WHICH AREAS WILL GET FREEZE WARNING AND WHICH WILL GET FROST ADVISORY...BUT LEANING TOWARDS FREEZE WARNING FOR INLAND EMPIRE/VALLEYS AND COACHELLA VALLEY AND FROST ADVISORY COASTAL AREAS AND SAN DIEGO COUNTY DESERTS.

MAY MAKE MINOR ADJUSTMENTS TO REMAINDER OF FORECAST THIS AFTERNOON BUT NOT ANTICIPATING ANY SIGNIFICANT CHANGES. A FIRE WEATHER WATCH WILL BE ISSUED FOR SUNDAY NIGHT THROUGH THURSDAY FOR INLAND VALLEYS AND MOUNTAINS. NORTHEAST WINDS GUSTING OVER 35 MPH EXPECTED FOR MONDAY AND TUESDAY PORTION WHILE RELATIVE HUMIDITY EXPECTED TO REMAIN VERY LOW THROUGH THURSDAY WITH WEAKER OFFSHORE FLOW PREVAILING. &&

.AVIATION... 12Z NKX SOUNDING INDICATES THE MARINE LAYER DEPTH WAS AROUND 7000 FEET THIS MORNING. MORNING ACARS SOUNDINGS FROM DEPARTURES OUT OF KSAN INDICATE THE INVERSION HAD LOWERED TO AROUND 6500 FEET BY SUNRISE WITH A STRONGER INVERSION SHOWING UP AROUND 12000 FEET. LAYERS OF STRATOCU OVER THE AREA WITH THE LOWEST SCATTERED LAYER AROUND 3000 FEET MSL WITH ANOTHER BROKEN LAYER AROUND 4000 FEET AND ANOTHER LAYER AROUND 6000 FEET. SATELLITE IMAGERY SHOWS RAPID CLEARING TAKING PLACE FROM THE NORTHWEST OVER THE NORTHERN AREAS WHICH SHOULD WORK ITS WAY SOUTHWARD DURING THE REST OF THE MORNING WITH MOST AREAS SCATTERING OUT BY AFTERNOON. EXPECT MOSTLY CLEAR CONDITIONS AT AREA AIRPORTS THIS AFTERNOON THROUGH SATURDAY.

MAIN PROBLEM WILL BE THE STRONG WEST TO NORTHWEST WINDS ACROSS THE MOUNTAINS THAT COULD PRODUCE SOME MOUNTAIN WAVE/ROTOR ACTIVITY ALONG THE LEE SIDE OF THE MOUNTAINS OVER THE COACHELLA VALLEY NEAR KPSP THROUGH THIS AFTERNOON AND EVENING. THE WINDS ARE EXPECTED TO BECOME NORTH TO NORTHEAST TONIGHT AND SATURDAY WITH THE MOUNTAIN WAVE/ROTOR MOVING TO THE LEE SIDE OF THE SAN BERNARDINO MOUNTAINS NEAR KONT AND KSBD SATURDAY MORNING.

&&

.MARINE... SMALL CRAFT ADVISORIES ARE IN EFFECT TODAY FOR STRONG POST FRONTAL WESTERLY WINDS FROM 15 TO 25 KTS. THE RESULTANT SHORT PERIOD WIND SWELL (4-5 SECONDS) COMBINED WITH AN INCREASING LONGER PERIOD WESTERLY SWELL (8-10 SECONDS) FROM 7 TO 9 FEET WILL PRODUCE HAZARDOUS BOATING CONDITIONS.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...

SNOW ADVISORY UNTIL 10 AM...HIGH DESERTS AND INLAND EMPIRE ABOVE 2000 FEET...SEE LAXWSWSGX.

SNOW AND BLOWING SNOW ADVISORY UNTIL 11 AM...SAN BERNARDINO AND RIVERSIDE COUNTY MOUNTAINS...SEE LAXWSWSGX. WIND ADVISORY FOR THE MOUNTAINS AND DESERTS THROUGH 8 PM. SEE LAXNPWSGX.

WIND CHILL ADVISORY TONIGHT...SAN BERNARDINO MOUNTAINS TO BE ISSUED AROUND 2 PM THIS AFTERNOON.

FROST ADVISORY LATE TONIGHT/SATURDAY MORNING...COASTAL SECTIONS...INLAND VALLEYS...COACHELLA VALLEY...SAN DIEGO COUNTY DESERT.

SMALL CRAFT ADVISORY THROUGH THE EVENING. SEE LAXCWFSGX.

HIGH RIP CURRENT RISK TODAY. SEE LAXSRFSGX.

FREEZE WATCH FOR THE INLAND VALLEYS AND LOWER DESERTS FROM SAT EVENING THROUGH MON MORNING. SEE LAXNPWSGX.

FIRE WEATHER WATCH SUNDAY NIGHT THROUGH THURSDAY...INLAND VALLEYS AND MOUNTAINS...TO BE ISSUED AROUND 2 PM THIS AFTERNON.

$$

PUBLIC/FIRE WEATHER...BALFOUR AVIATION/MARINE.......HORTON

.UPDATE...

WE UPDATE THE FORECAST FOR TODAY AND EARLY TONIGHT. THIS WAS BASED ON RADAR ECHOS. THE SOUNDING AT DVN THIS MORNING SUGGEST DRIZZLE AND MAYBE SOME FREEZING DRIZZLE. IT IS DRY IN THE CRYSTAL GROWTH AREA. THE ACARS SOUNDING AT ORD SHOWS DRIZZLE FOR NOW. BUT AS THE COLD AIR MOVES IN THERE COULD BE SOME FREEZING DRIZZLE. WE DO NOT EXPECT MUCH FREEZING DRIZZLE AT THIS TIME. SO WE WILL NOT ISSUE AN ADVISORY AT THIS TIME. WE WILL WAIT UNTIL WE SEE HOW THE PRECIPITATION CONTINUES WHEN THE SURFACE TEMPERATURES GO BELOW FREEZING.

&&

.DISCUSSION FOR MORNING GRIDS/ZONES... 500 AM CST

SHORT WAVE HAS CONTINUED TO MOVE QUICKLY ACROSS THE GREAT LAKES AND IS NOW APPROACHING THE LOWER ST LAWRENCE VALLEY WHILE ANOTHER IS MOVING ACROSS SOUTHER ONTARIO ND A THIRD INTO MN. THE SURFACE COLD FRONT HAS BEEN SLOW IN ITS SOUTHEASTWARD ADVANCEMENT OVERNIGHT AND IS LOCATED FROM FAR SE WI INTO NORTHERN AND W CENTRAL IL EARLY THIS MORNING. WHILE COLDER AIR WILL BE ADVECTING INTO THE REGION AS THE BOUNDARY CONTINUES TO SLIP SOUTHEAST TODAY...EVENTUALLY REACHING THE OZARKS AND LOWER OH VALLEY BY 00Z SAT...THE COLD AIR WILL BE HELD OFF FOR A WHILE AS IT REMAINS ACROSS THE NORTHERN PLAINS AND NORTH WOODS INTO SOUTH CENTRAL CANADA AND THE CORE OF THE ARCTIC AIR STAYS IN NORTHERN CANADA WHILE SOUTHWESTERLY UPPER FLOW FROM THE WESTERN U.S. TROF REACHES NORTHEASTWARD ACROSS THE GREAT LAKES TO THE CANADIAN MARITIMES. SEVERAL FORECAST PROBLEMS THROUGH THE WEEKEND CONCERNING PRECIP TYPES AND TIMING. SHALLOWER COLD AIR WILL CONTINUE TO ADVECT OVER THE FA THE COLD HI PRES RIDGE BUILDS SLOWLY SE ACROSS THE DAKOTAS AND THE UPPER S VALLEY TODAY AND TONIGHT. THIS SHOULD COOL LOWER PORTION OF COLUMN TO SUPPORT SOME PL ACROSS THE NRN PARTS OF THE FA TODAY. WITH BOUNDARY WELL S...SFC WAVE TO TRAVEL ALONG IT LATER THIS AFTERNOON AND TONIGHT WILL KEEP MAIN PRECIP AREA ACROSS SRN AND CNTRL IL INTO MUCH OF IND...BUT WITH WSW FLO CONTINUING OVR THE FA AHEAD OF THE H8 TROF THE NORTHERN EDGE OF THE PRECIP SHIELD MAY ENCROACH INTO SOUTHERN AND EASTERN PORTIONS. THERMAL PROFILES SUGGEST A RANGE FROM LIGHT SNOW OR FLURRIES NW TRANSITIONING TO A BAND OF MIXED RAIN...SLEET AND FREEZING RAIN...THEN JUST RAIN IN THE FAR SE COUNTIES.

AS WESTERN UPPER TROF MOVES OVER THE ROCKIES AND OUT OVER THE PLAINS SUNDAY MODELS SUGGEST AN ELONGATED H8 CIRCULATION TO TREK FROM MO ACROSS CENTRAL IL AND TO SE LOWER MI BY 12Z MON. THIS PUTS THE REGION AT RISK FOR A SOMEWHAT SIGNIFICANT PRECIP EVENT FOR SUNDAY AND SUNDAY NIGHT. AGAIN...DEPTH OF COLD AIR IN LO LEVELS AND HOW MUCH WAA ADVECTION OCCURS ABOVE THIS COLD LAYER WILL DETERMINE WHERE PRECIP TRANSITIONS FROM PURE SN TO MIXED SNOW AND SLEET. ATTM THIS WOULD APPEAR TO BE ACROSS THE SRN PORTION OF THE FA AS MODELS ONLY INDICATING WEAK H8 FLOW NWRD OVER THE COLD DOME. NECESSITY FOR SOME SORT OF WINTER WX ADVISORIES FOR SNOW/SLEET/FREEZING RAIN LIKELY TO BE NECESSARY FOR AT LEAST PARTS OF FA BUT NEED TO HAVE DETAILS MORE CLEARLY INDICATED FOR THAT.

FOR FIRST PART OF NEXT WEEK COLD BUT CERTAINLY NOT OUT OF ORDINARY FOR MID JAN...AT LEAST DURING A MORE TYPICAL WINTER. COLD DOES NOT APPEAR TO BE VERY LONG LIVED AS BY LATE WEEK TEMPS MODERATE ONCE AGAIN WITH UPPER FLOW RETURNING TO OFF OF PACIFIC. TRS

&&

.AVIATION... 1200 PM CST

FOR THE 18Z TAFS...FRONTAL BOUNDARY SLOWLY MOVING SOUTH FROM CURRENT POSITION INVOF A ORD-PNT LINE. AS COLDER AIR ASSOCIATED WITH THIS BOUNDARY ENCOUNTERS THE VERY MOIST AIR OUT AHEAD OF THE FRONT...LIFR CIGS ARE RESULTING. SCT -SN/RA OVR SERN IA IS TRACKING NEWD AT 60KTS IN CONJUNCTION WITH A WEAK MID-LEVEL DISTURBANCE. AT CURRENT PACE...THIS PRECIP SHOULD REACH RFD AROUND 19Z AND ORD/MDW/DPA AROUND 20Z. LOW LEVEL TEMPS STILL ABV FREEZING BUT WILL BE DIPPING BELOW THAT BY EVENING IN THE RFD AREA. VERTICAL TEMP PROFILES COOL BELOW 0 DEG C AT THE CHICAGO AREA TERMINALS LATE THIS EVENING. SATURATED SUB-FREEZING LAYER BTWN THE SFC AND ~5KFT SHOULD ONLY BE ABOUT -5 TO -8C AT ITS COLDEST POINT. THUS...SNOWFLAKE GENERATION OVERNIGHT MAY BE HARD PRESSED TO HAPPEN...LEAVING SUPERCOOLED LIQUID (FZDZ) THE MOST LIKELY SCENARIO. HEAVIER PRECIP SHOULD REMAIN WELL SOUTH OF THE LOCAL TERMINALS THROUGH THE NEXT 24HRS. CIGS SHOULD CLIMB BACK INTO MVFR RANGE BY MORNING AS 1035-MB HIGH TO THE NW NUDGES DRIER AIR DEEPER INTO OUR AREA.

HANDEL

&&

.LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...NONE. &&

$$

.UPDATED AT 1245 PM...JET STREAK PRODUCING ENOUGH LIFT TO SQUEEZE OUT SOME FREEZING DRIZZLE AND SNOW FLURRIES IN THE SOUTHEAST THIRD OF THE FORECAST AREA. THIS SHOULD CONTINUE INTO THE EARLY EVENING. GROUND TEMPERATURES ARE WARM...SO NOT SURE WHETHER WE WILL GET ICING ON ROADS OR NOT. IF WE START GETTING ICING REPORTS WE MAY ISSUE A WINTER WEATHER ADVISORY.

.SHORT TERM...TODAY THROUGH SATURDAY. FLAT RIDGE OVER SOUTHEASTERN U.S. WITH POS TILTED TROF EXTENDING FROM HUDSON BAY TO THE GREAT BASIN. AT THE SURFACE...FRONT NOW OVER SOUTHEAST PORTION OF CWA...MOVEMENT SLOWER THAN MODELS INDICATED IN PREVIOUS RUNS. HIGH PRESSURE BUILDING IN FROM THE NORTHERN PLAINS WITH VERY COLD AND DRY AIRMASS. WIDESPREAD LOW CLOUDS OVER STATE ATTM WITH SATELLITE INDICATING SOME CLEARING OVER FAR WESTERN WI. NOT MAKING GREAT HEADWAY EAST AT THIS TIME. MID AND HIGH CLOUDS LIFTING NORTH THROUGH NORTHWEST WI ASSOCIATED WITH JET PULLING INTO SOUTHERN CANADA. SOME LIGHT RETURNS SEEN ON AREA RADARS THIS AREA...THOUGH NOTHING SEEN AT SURFACE.

THIS PERIOD TO REMAIN RATHER QUIET WITH HIGH PRESSURE OVER THE AREA. FORECAST CONCERNS CENTER ON CLOUD FORECAST. MODEL CROSS SECTIONS INDICATE LOW CLOUDS HANGING TOUGH THROUGH TODAY...SOME DRYING FROM THE NORTH LATER TONIGHT INTO SATURDAY. WILL STAY WITH MOSTLY CLOUDY FORECAST TODAY...THEN DIMINISH CLOUDS THROUGH SAT NORTH AND WEST AS HIGH WORKS IN. SOUTHERN PORTION OF CWA EXPECTED TO SEE MORE IN THE WAY OF MID AND HIGH CLOUDS AS WAVES RIDE NORTHEAST ALONG BAROCLINIC ZONE TO THE SOUTH OF STATE. STRONG CAA TODAY WILL ALLOW FOR FALLING TEMPS THROUGH THE DAY.

OTHER CONCERN THIS PERIOD IS SMALL CHANCE OF LAKE EFFECT THIS AFTERNOON INTO TONIGHT OVER NORTH CENTRAL. HAVE BACKED OFF ON COVERAGE AND POPS A BIT. LOW LEVEL WINDS NEVER IDEAL WITH TOO MUCH SHEAR IN THE LOWER LEVELS...THEN BACK WEST BY SAT AM.

AVIATION...UPDATED AT 1245 PM. TAMDAR SOUNDINGS FROM CWA AND ATW SHOW LOTS OF MOISTURE BELOW 800 MB BUT DRY ABOVE. TEMPERATURES ALL ABOVE - 10C...SO NOT MUCH CHANCE OF SNOW JUST FZDZ. CEILINGS SHOULD SLOWLY CLIMB DURING LATE AFTERNOON AND EVENING.

.LONG TERM...SAT NGT THRU NXT THU. MAIN FCST FOCUS CENTERS AROUND POTENTIAL FOR SNOW ACROSS NE WI THIS WEEKEND INTO EARLY NXT WEEK. WL ALSO HAVE TO DEAL WITH TEMPS THEREAFTER AND THE DEPTH OF THE COLD AIR INTRUSION.

AS THE UPR TROF DIGS TOWARD THE FOUR CORNERS RGN SAT NGT...A LEAD SHRTWV IS PROGGED TO LIFT NE INTO THE MIDWEST. WHILE BETTER FORCING WL REMAIN TO OUR SOUTH...CANNOT RULE OUT THAT THE NRN EDGE OF ANY PCPN WOULD APPROACH SRN SECTIONS OF THE FCST AREA. PREFER TO ADD A SLGT CHC OF LGT SNOW GENERALLY SOUTH OF A ISW-SUE LINE. OTHERWISE...PLENTY OF CLDS EXPECTED OVR THE REST OF NE WI WITH MIN TEMPS IN THE SINGLE DIGITS AND TEENS. THE INITIAL SHRTWV AND ASSOCIATED FORCING SHIFT EAST BY SUNDAY. AS THE UPR TROF PUSHES TOWARD THE CNTRL/SRN PLAINS AND CANADIAN HI PRES DROPS SOUTH INTO THE NRN PLAINS...SFC WNDS ARE EXPECTED TO VEER MORE N-NE DURING THE DAY. 8H TEMPS RESIDING AROUND -14C OVR NRN LK MI AND -20C OVR WRN LK SUPERIOR MAY ALLOW FOR SOME SNOW SHWRS TO MOV INTO EXTREME ERN WI/NRN WI. EXACT WND DIR WL BE KEY WHETHER ANY SNOW SHWRS AFFECT KEWAUNEE/MANITOWOC COUNTIES OR REMAIN OFFSHORE. PREFER TO GO DRY ESLEWHERE AS THERE IS NO OTHER TRIGGER PRESENT.

UPR TROF IS PROGGED TO MOV INTO THE CNTRL PLAINS SUNDAY NGT WITH THE SFC LOW TO TRACK FROM THE OZARKS NEWD INTO THE OHIO RIVER VALLEY. IF THIS SCENARIO PLAYS OUT THIS WAY...THE HEAVIER SNOW WOULD STAY TO OUR SOUTH AND EAST WITH OUR SNOW MORE OF A RESULT OF THE DEFORMATION ZN. HIGHEST POPS TO REMAIN OVR THE SRN TIER OF COUNTIES WITH A SHARP CUT-OFF TO ONLY SLGT CHC POPS FOR THE NRN HALF OF THE FCST AREA. APRS NOW THAT NOTHING MORE THAN AN INCH OR TWO PSBL SUNDAY NGT. INITIAL UPR TROF PUSHES INTO THE GREAT LKS RGN ON MON AS ANOTHER UPR TROF DIGS TOWARD THE DESERT SW. LINGERING CHCS OF LGT SNOW EXPECTED OVR CNTRL/E-CNTRL WI...WITH THE POTENTIAL OF ADDL LK EFFECT SNOW SHWRS ADDING SOME MINOR ACCUMULATIONS TO THE LKSHR COUNTIES. WL CONT THE LIKELY WORDING FOR DOOR...KEWAUNEE... AND MANITOWOC COUNTIES. WL HAVE TO WATCH TEMPS AS LACK OF NEW SNOW MAY ALLOW TEMPS TO WARM MORE THAN PREVIOUSLY THOUGHT.

NORTHERLY WNDS TO PERSIST RIGHT INTO TUE AS HI PRES BEGINS TO BUILD EAST TOWARD THE WRN GREAT LKS. TRAJS WOULD CONT TO FAVOR A CHC OF LK EFFECT SNOW SHWRS OVR VILAS CNTY WHILE AREAS NEAR LK MI APR TO BE ON THE FRINGES OF SNOW SHWRS MOVG SOUTH OVR LK MI. PREFER TO ADD FLURRIES RIGHT ALONG THE SHORELINE AS TRAJS SEEM TOO MUCH DUR NORTH TO BRING SNOW INLAND. HAVE NUDGED TEMPS UP A DEG OR TWO BASED AGAIN ON THE LACK OF FRESH SNOW. HI PRES TO BE SITUATED OVR THE RGN ON WED USHERING IN DRIER AIR AND BACKING WNDS. ANY LK EFFECT SNOW WOULD END...THUS HAVE KEPT DRY CONDITIONS GOING FOR NE WI WED. COLDEST OF THE AIRMASS TO START SHIFTING EWD BY WED SO AN UPTICK IN TEMPS SHOULD BEGIN.

SPLIT FLOW TO RETURN BY THE MIDDLE OF NXT WEEK WITH MDLS HINTING AT A NRN STREAM SYSTEM TO DROP SE INTO THE GREAT LKS NXT THU. TIMING ISSUES COME INTO PLAY HERE SO HAVE LEFT THU DRY FOR NOW. IF SUCCESSIVE MDL RUNS CONT TO SHOW THIS SYSTEM MOVG IN...POPS WOULD NEED TO BE ADDED.

&&

.GRB WATCHES/WARNINGS/ADVISORIES... NONE &&

$$ RDM/ECKBERG WEATHER.GOV/GREENBAY