Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 02/19/05

.UPDATE... MAIN FCST CONCERNS OVERNIGHT ARE LES TRENDS.

WV IMAGERY AND RUC ANALYSIS INDICATED WEAK CLIPPER SHRTWV HAD SLIPPED SE INTO NRN LWR MI. TRAILING AREA OF 280K ISENTROPIC LIFT SUPPORTED AN AREA OF -SN OVER N AND CNTRL WI. AT THE SFC...A TROF MOVING FROM WRN LK SUPERIOR INTO W UPR MI. 950 CONV ALONG WITH TEMPS TO AROUND -20C AROUND H8 INVERSION...PER 23Z TAMDAR SNDG...ALONG WITH MOIST 850-700 LYR PROVIDED FAVORABLE CONDITIONS FOR LES INTO THE KEWEENAW. SO FAR...ONLY INTERMITTENT HEAVIER SHSN WERE OBSERVED BUT KCMX WINDS HAVE ALSO REMAINED SW. IR IMAGERY STILL SUGGESTS POTENTIAL FOR HEAVIER LES BANDS TO MOVE ONSHORE.

EXPECT OCNLY HEAVY SHSN TO CONTINUE OVER NW UPR MI TIL WINDS VEER NW FROM 06Z-09Z AND BEST 950 CONV SHIFTS TO THE SOUTH. WINDS TO 320-300 LATE SHOULD ALSO BRING AT A FEW INCHES TO ONTONAGON...SRN HOUGHTON AND PORTION OF GOGEBIC COUNTY NEAR THE PORCUPINE MTS. LES SHOULD DIMINISH LATE WITH INCREASING QDIV/SUBSIDENCE...850-700 DRYING AND TRANSITION TO SHORTER FETCH. SO...LES ADVY LEFT INTACT FOR ADDITIONAL 1-3 INCH AMOUNTS OVERNIGHT. VEERING WINDS TO NW WILL EVENTUALLY PUSH LES INTO NE UPR MI...MAINLY BTWN 09Z-12Z. GIVEN LATER ONSET...GOING FCST OF 1-2 INCHES LOOKS ON TRACK. OTHERWISE...PATCH -SN/FLURRIES...MAINLY OVER THE SOUTH WILL ALSO DIMINISH...PER ETA 280K PROG.

&&

JLB

.PREV DISCUSSION...FOR LATER PERIODS ISSUED 350 PM EST FRI FEB 18 2005

LINGERED SNOW SHOWERS LONGER FOR SAT IN W ZONES WITH LOWER LEVEL CONVERGENCE PROGGED TO EASE ONLY AFTER 15Z. LIMITING FACTORS MENTIONED EARLIER WILL ONLY BE INCREASING BY THIS TIME AND WILL KEEP ACCUMS TO AROUND AN INCH. FLOW BECOMING SE LATER SAT AFTN INTO SAT NIGHT WILL PUSH LK EFFECT OFFSHORE BY LATE SAT EVENING. KEPT LOW TEMPS BLO ZERO FOR INTERIOR SAT NIGHT WITH RIDGING OVERHEAD. EXPECT ONLY MID-HIGH CLOUDS FM APPROACHING TROUGH TO SPILL INTO SW ZONES VERY LATE.

SUN INTO MON...STILL VARYING SOLNS FOR COMBO OF S BRANCH/N BRANCH SHORTWAVES TO AFFECT REGION. NOW APPEARS THAT MODELS COMING INTO AGREEMENT THAT BRANCHES WILL REMAIN UNPHASED AS TROUGHS CROSS AREA. THIS SHOULD ALLOW SFC LOW TO GENERALLY MOVE W TO E FM CNTRL MS RIVER VALLEY INTO N FRINGES OF OHIO RIVER VALLEY. LOW TRACKS VARY FM FARTHER N GFS/CANADIAN TO THE S ETA/NAM...UKMET...AND ECMWF. AS IT LOOKED LIKE A COUPLE DAYS AGO...THIS SOLN MAKES SENSE AS HIGH PRES RIDGE HOLDS OVR GREAT LAKES AS LATE AS SUN AND PERSISTENT SE WINDS WILL ADVECT DRIER AIRMASS INTO OUR CWA AHEAD OF THE LOW/INVERTED TROUGH. UNCERTAINTY IN THIS TIME FRAME SO MADE FEW CHANGES WITH GOING CHANCE OF SNOW FOR ALL CWA. POTENTIAL LATER CHANGES WOULD BE DELAYING ONSET OF LGT SNOW FOR SUN MORNING IF DRIER AIR HOLDS LONGER (AS SHOWN BY ETA/NAM)...AND SCALING BACK POPS FOR N HALF OF CWA. EDGE OF SNOW LOOKS PRETTY CERTAIN TO AT LEAST AFFECT THE FAR S...SO WENT WITH LIKELY POPS FOR S HALF OF MENOMINEE COUNTY SUN PM INTO SUN NIGHT.

EXTENDED (TUE THROUGH FRI)...LITTLE CHANGE IN MEDIUM RANGE GUIDANCE FM YDY SOLNS. LOW PRES TROUGH PASSES OVR UPR LAKES EARLY IN THE WEEK AND USHERS IN BRIEF COOL SHOT (H85 TEMPS AROUND -14C) FOR TUE/WED. HIGH PRES BUILDS IN LATER WED THROUGH FRI DUE TO UPR CONFLUENCE BTWN DEPARTING N BRANCH AND S BRANCH TROUGH EMERGING FM SW CONUS. WARM AIR ADVECTION DEPICTED OVR UPR PLAINS AND POSSIBLY INTO UPR LAKES TOWARD END OF WEEK. OVERALL...OTHER THAN THE LIGHT WNW FLOW LK EFFECT REGIME THROUGH WED THEME OF EXTENDED IS TRANQUIL WITH SLOWLY MODERATING TEMPS.

COORD WITH APX.

&& MQT...WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY TONIGHT MIZ001-003. HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. &&

$$ JLA(PREV DISC)



.DISCUSSION...

WV LOOP/RAOBS INDICATE DECENT SHORTWAVE PRESSING INTO NW WI ATTM. 17Z TAMDAR SOUNDING NEAR KINL SHOWED DEEP MOISTURE TO H6 WITH OBS AND DLH RADAR INDICATING MAINLY LGT SNOW (3-5 SM VISIBILITY) BUT A FEW POCKETS OF MODERATE SNOW WERE ALSO OBSERVED. SWATH OF LGT SNOW/FLURRIES SHOULD CRUISE SE WITH SHORTWAVE AND AFFECT MUCH OF CWA THIS EVENING. MAYBE SOME ACCUMULATION (ESPECIALLY FAR W) WITH THIS SHOT OF SNOW BUT IT WILL PROBABLY BE JUST A DUSTING. PRIMARY CONCERN IS IN VERY SHORT TERM (THIS EVENING THROUGH A BIT AFTER MIDNIGHT) AS THE SHORTWAVE AND UPWARD MOTION AND DEEPER MOISTURE ACT UPON ONGOING LK EFFECT OVR W LK SUPERIOR. FLOW HAS BACKED SW AHEAD OF TROUGH WITH TROUGH AXIS STILL UPSTREAM OVR CNTRL MN. VIS SAT SHOWS DOMINANT BAND OF SNOW HAS DEVELOPED WITHIN LAST COUPLE HOURS FM N OF APOSTLE ISLANDS TOWARD ISLE ROYALE. WEB CAM FM EAGLE HARBOR POINT TO THE GROWING LK EFFECT WITH DARKENING CLOUDS OUT OVR WRN LK SUPERIOR.

EXPECT THIS DOMINANT BAND TO SHIFT ONSHORE IN KEWEENAW COUNTY THIS EVENING...THEN INTO N HOUGHTON COUNTY BY MIDNIGHT. NAM40 AND LOCAL WSETA INDICATED MOST CONVERGENCE IN 950-925MB TO AFFECT S PORTION OF KEWEENAW COUNTY INTO N PART OF HOUGHTON COUNTY THROUGH 06Z...THEN TO DECREASE AS BAND ATTEMPS TO SHIFT S INTO REST OF LK SUPERIOR BORDERING ZONES. SINCE SHORTWAVE/DEEPER MOISTURE DEPART BY 06Z LEAVING ONLY SHALLOW LAYER OF MOISTURE LESS THAN 5KFT WITH OVER WATER DLT T/S NEARING 20C...EXPECT BULK OF HEAVY LK EFFECT TO OCCUR OVR THE KEWEENAW PENINSULA BTWN 02Z AND 07Z (9 PM TO 2 AM EST). SOME BRIEF GUSTS OF WIND WITH TROUGH PASSAGE...BUT NOT EXPECTED SUSTAINED REDUCTION TO VISIBILITY DUE TO WIND/SNOW. THEREFORE...NEED 8"/12 HR TO JUSTIFY WARNING VIA SNOW AMOUNTS. ALTHOUGH EAGLE RIVER-COPPER HARBOR STRETCH IS INFAMOUS FOR THESE INTENSE QUICK HITTING SW FLOW EVENTS WITH SNOWFALL RATES OF 1-3"/HR...LACK OF LONG LASTING DEEP MOISTURE/LIFT FM QUICK MOVING SHORTWAVE WILL KEEP SNOW AMOUNTS IN CHECK. EXPECT SNOWFALL TOTALS TONIGHT AS HIGH AS 6" OVR THE AREAS HIGHLIGHTED EARLIER...BUT BELIEVE A LK EFFECT SNOW ADVISORY WILL COVER THE SITUATION INSTEAD OF A WARNING. WILL ONLY RUN THROUGH DAYBREAK AS SNOW TOMORROW SHOULD ONLY PRODUCE MINOR ACCUMULATIONS.

CYCLONIC NW FLOW AND SUFFICIENT INSTABILITY WILL PUSH SOME SNOW SHOWERS INTO GOGEBIC/ONTONAGON/BARAGA/NW MARQUETTE AFTER MIDNIGHT BUT LOWERING INVERSIONS AND DECREASING MOISTURE BLO INVERSION WILL LIMIT ACCUMS TO LESS THAN ADVY CRITERIA. LINGERED SNOW SHOWERS LONGER FOR SAT IN W ZONES WITH LOWER LEVEL CONVERGENCE PROGGED TO EASE ONLY AFTER 15Z. LIMITING FACTORS MENTIONED EARLIER WILL ONLY BE INCREASING BY THIS TIME AND WILL KEEP ACCUMS TO AROUND AN INCH. FLOW BECOMING SE LATER SAT AFTN INTO SAT NIGHT WILL PUSH LK EFFECT OFFSHORE BY LATE SAT EVENING. KEPT LOW TEMPS BLO ZERO FOR INTERIOR SAT NIGHT WITH RIDGING OVERHEAD. EXPECT ONLY MID-HIGH CLOUDS FM APPROACHING TROUGH TO SPILL INTO SW ZONES VERY LATE.

SUN INTO MON...STILL VARYING SOLNS FOR COMBO OF S BRANCH/N BRANCH SHORTWAVES TO AFFECT REGION. NOW APPEARS THAT MODELS COMING INTO AGREEMENT THAT BRANCHES WILL REMAIN UNPHASED AS TROUGHS CROSS AREA. THIS SHOULD ALLOW SFC LOW TO GENERALLY MOVE W TO E FM CNTRL MS RIVER VALLEY INTO N FRINGES OF OHIO RIVER VALLEY. LOW TRACKS VARY FM FARTHER N GFS/CANADIAN TO THE S ETA/NAM...UKMET...AND ECMWF. AS IT LOOKED LIKE A COUPLE DAYS AGO...THIS SOLN MAKES SENSE AS HIGH PRES RIDGE HOLDS OVR GREAT LAKES AS LATE AS SUN AND PERSISTENT SE WINDS WILL ADVECT DRIER AIRMASS INTO OUR CWA AHEAD OF THE LOW/INVERTED TROUGH. UNCERTAINTY IN THIS TIME FRAME SO MADE FEW CHANGES WITH GOING CHANCE OF SNOW FOR ALL CWA. POTENTIAL LATER CHANGES WOULD BE DELAYING ONSET OF LGT SNOW FOR SUN MORNING IF DRIER AIR HOLDS LONGER (AS SHOWN BY ETA/NAM)...AND SCALING BACK POPS FOR N HALF OF CWA. EDGE OF SNOW LOOKS PRETTY CERTAIN TO AT LEAST AFFECT THE FAR S...SO WENT WITH LIKELY POPS FOR S HALF OF MENOMINEE COUNTY SUN PM INTO SUN NIGHT.

EXTENDED (TUE THROUGH FRI)...LITTLE CHANGE IN MEDIUM RANGE GUIDANCE FM YDY SOLNS. LOW PRES TROUGH PASSES OVR UPR LAKES EARLY IN THE WEEK AND USHERS IN BRIEF COOL SHOT (H85 TEMPS AROUND -14C) FOR TUE/WED. HIGH PRES BUILDS IN LATER WED THROUGH FRI DUE TO UPR CONFLUENCE BTWN DEPARTING N BRANCH AND S BRANCH TROUGH EMERGING FM SW CONUS. WARM AIR ADVECTION DEPICTED OVR UPR PLAINS AND POSSIBLY INTO UPR LAKES TOWARD END OF WEEK. OVERALL...OTHER THAN THE LIGHT WNW FLOW LK EFFECT REGIME THROUGH WED THEME OF EXTENDED IS TRANQUIL WITH SLOWLY MODERATING TEMPS.

COORD WITH APX.

&& MQT...WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY TONIGHT MIZ001-003. HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. &&

$$ JLA



.UPDATED SHORT TERM (TONIGHT)... CLOUDS HOLDING TOUGH ACROSS MUCH OF THE AREA TNGT ALTHOUGH SAT LOOP SHOWS THEY ARE CLEARLY ON THEIR WAY OUT. FOR NOW WILL REWORD ZONES TO ACCOUNT FOR CLOUDS EARLY WITH THE CLEARING REACHING THE AREA EITHER AFTER MIDNIGHT OR LATE DEPENDING ON LOCATION. CLOUDS DID BREAK IN THE EAST BUT LOOKS LIKE THEY WILL FILL BACK IN DURG THE NEXT FEW HOURS SO WL JUST GO WITH THE ABV CLRG TREND. NO MAJ CHG IN FCST LOWS ATTM. IF CLOUDS DO CLR OUT WOULD XPC FCST TO BE REACHED EASILY GVN VERY LOW DWPTS &&

.AVIATION (00Z-00Z)... THE ONLY WEATHER TO SPEAK OF IS A FEW LAKE EFFECT LIGHT SNOW SHOWERS EAST OF KCLE ...WHICH WILL MOVE EAST AND END BY SATURDAY MORNING AS HIGH PRESSURE STRETCHING FROM MID MISSISSIPPI VALLEY AND ACROSS WESTERN OHIO...MOVES SLOWLY EAST. MOST OF FORECAST AREA COVERED WITH OVC035-040. CLEARING NOW INTO CENTRAL INDIANA MOVING E AT APPROXIMATELY 10-15 KTS. AS HIGH MOVES EAST SKIES SHOULD BECOME SCATTERED TO SKC OVER ENTIRE FORECAST AREA BY EARLY AFTERNOON ON SATURDAY. &&

.PREVIOUS SHORT TERM(TONIGHT THROUGH MON NIGHT)... DESPITE THE HIGH PRES RIDGE BUILDING INTO THE REGION...PLENTY OF LIGHT LAKE EFFECT SNOW SHOWERS CONTINUE IN THE SNOW BELTS. SNOW IS DIMINISHING UNDER NVA AND A LOWERING INVERSION SEEN PER TAMDAR DATA. FLOW WILL SLOWLY START TO BACK THIS EVENING IN RESPONSE TO THE RIDGE BUILDING OVER OHIO AND THE FLOW WILL EVENTUALLY BECOME SLIGHTLY OFFSHORE DUE TO A WK LAND BREEZE. SATELLITE AND RADAR SUGGEST THAT PLENTY OF WK LES BANDS CONTINUE ATTM...WHICH WILL REQUIRE LKLY POPS FOR THE SNOWBELTS THIS EVENING. HOWEVER...AS FLOW BACKS AND EVEN DRIER AIR MOVES INTO THE REGION...WILL BE ABLE TO CUT POPS TO SCT BY MIDNIGHT. CLDS SHOULD ALSO DIMINISH AS THE FLOW BACKS...ESPECIALLY OVER INLAND AREAS OF OHIO. THIS WILL ALLOW FOR DECENT RADIATIONAL COOLING OVERNIGHT...AND HAVE OPTED TO CUT BACK TEMPS TONIGHT WITH TEMPS IN THE 5-10 DEG RANGE. COULD POSSIBLY SEE TEMPS COLDER IF WINDS CAN DECOUPLE COMPLETELY. THIS WOULD BE MOST LIKELY SOUTHERN AREAS AS NEXT SYSTEM OVER THE UPR MS VLY WILL BE APPROACHING THE NRN AREAS LATE.

SATURDAY SHOULD BE GENERALLY QUIET DESPITE THE FACT THAT A WEAK TROUGH/COLD FNT WILL BE MOVING THRU THE AREA DURING THE DAY. THIS SYSTEM WILL LIKELY BE DRY...ALTHOUGH ENOUGH MOISTURE WILL REMAIN IN PLACE OVER THE NE AREAS TO WARRANT SMALL CHC POPS MAINLY ALONG THE LAKESHORE EAST OF CLE. WILL NOT BRING POPS INLAND MAINLY DUE TO THE FLOW BEING SWLY AHD OF THE FNT AND LITTLE MOISTURE TO WORK WITH OTHER THAN THAT FROM THE LAKE. FLOW TURNS NWLY BEHIND THE FRONT BUT MOISTURE IS SIGNIFICANTLY LACKING WITH LITTLE IF ANY DYNAMICS. WILL GO WITH CHC POPS IN THE SNOW BELTS SAT NIGHT...BUT DO NOT THINK THAT SNOW ACCUMULATIONS FROM THE SNOW SHOWERS WILL BE SIGNIFICANT DUE TO INVERSION BEING 4-5KFT.

BIG MODEL DIFFERENCES SUN AND SUN NIGHT WITH NEXT SYSTEM CURRENTLY STILL OVER CA. THIS SRN SYSTEM WILL TRY TO PHASE OVER THE PLAINS WITH A WEAKER NRN STREAM SYSTEM DIVING OUT OF CANADA. MDLS DIFFER ON THE TIMING...WITH THE ETA BEING SLOWER AND FARTHER SOUTH WHILE THE GFS IS A LITTLE FASTER AN N. THE ETA WOULD SUGGEST MUCH OF THE PCPN BEING SNOW...WHILE THE GFS WOULD SUGGEST A PERIOD OF SNOW MIXING WITH OR CHANGING OVER TO SNOW BY EVENING MOST AREAS. FCST FOR THIS TIME PERIOD QUITE COMPLEX NOT ONLY WITH PCPN TYPE...BUT ALSO WITH TRACK OF THE LOW AND TIMING OF PCPN. THE GFS TRACK N AND W OF OHIO WOULD SUGGEST PCPN SUN AND SUN EVENING...THEN THE AREA BECOMES DRY SLOTTED. HOWEVER...THE ETA TRACK ALONG I-70 AND SLOWER WOULD IMPLY THE PCPN STARTING LATER IN THE DAY ON SUN WITH MORE FROZEN PCPN OVER THE ENTIRE AREA. AM TRENDING SOMEWHAT TOWARD THE GFS FOR NOW...RECOGNIZING THAT THE ETA SOLN IS FEASIBLE AND KEEP AT LEAST A MIXTURE OF PCPN FOR THE ENTIRE AREA IN THE FCST. ALTHOUGH IT SEEMS NEARLY CERTAIN THAT THE ENTIRE AREA WILL SEE PCPN SUN OR SUN NIGHT (OR BOTH PERIODS) WITH STRONG UPR DYNAMICS...WITH THE MDL DIFFERENCES HAVE OPTED TO JUST KEEP LKLY POPS FOR BOTH PERIODS FOR NOW. REGARDLESS OF MDL SOLN...BOTH START THE PCPN OUT AS ALL SNOW AND HAVE FOLLOWED THIS IN THE FCST. WHERE IT STAYS SNOW THE LONGEST...2-4 INCHES IS POSSIBLE BEFORE THE CHANGEOVER OCCURS (IF IT DOES).

WILL NEED TO KEEP CHC POPS IN FOR MONDAY TO ACCT FOR MDL TIMING DIFFS. HOWEVER...IF THE GFS VERIFIES IT WILL BE MAINLY DRY MONDAY...ESPECIALLY WEST. IF THE ETA VERIFIES...POPS WILL NEED TO BE HIGHER MONDAY.

&&

.LONG TERM(TUE THROUGH FRI)... DESPITE THE SHORT TERM MODEL DIFFERENCES...THE MED RANGE MODELS ARE IN GOOD AGREEMENT IN THE EXTENDED...WHICH ALLOWS FOR RELATIVELY HIGH CONFIDENCE IN THE EXTENDED FCST. AFTER THE SUN/SUN NIGHT SYSTEM E... HIGH PRES WL BUILD INTO THE GREAT LAKES THRU FRIDAY. THE GFS SHOWS THAT COLD AIR WILL MOVE S OVER THE SRN LAKES MON NIGHT AND TUE WHICH MAY ALLOW FOR SOME MINOR LES THRU TUE. HOWEVER...OVERALL THE EXTENDED SHOULD BE VERY QUIET WX WITH TEMPS NR NORMAL WITH NO MAJOR COLD SPELLS. &&

.CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE.

&& SHORT TERM UPDATE...TK PRVS SHORT TERM...MRD LONG TERM...MRD AVIATION...DJB

$$



.AVIATION (00Z-00Z)... THE ONLY WEATHER TO SPEAK OF IS A FEW LAKE EFFECT LIGHT SNOW SHOWERS EAST OF KCLE ...WHICH WILL MOVE EAST AND END BY SATURDAY MORNING AS HIGH PRESSURE STRETCHING FROM MID MISSISSIPPI VALLEY AND ACROSS WESTERN OHIO...MOVES SLOWLY EAST. MOST OF FORECAST AREA COVERED WITH OVC035-040. CLEARING NOW INTO CENTRAL INDIANA MOVING E AT APPROXIMATELY 10-15 KTS. AS HIGH MOVES EAST SKIES SHOULD BECOME SCATTERED TO SKC OVER ENTIRE FORECAST AREA BY EARLY AFTERNOON ON SATURDAY. &&

.SHORT TERM(TONIGHT THROUGH MON NIGHT)... DESPITE THE HIGH PRES RIDGE BUILDING INTO THE REGION...PLENTY OF LIGHT LAKE EFFECT SNOW SHOWERS CONTINUE IN THE SNOW BELTS. SNOW IS DIMINISHING UNDER NVA AND A LOWERING INVERSION SEEN PER TAMDAR DATA. FLOW WILL SLOWLY START TO BACK THIS EVENING IN RESPONSE TO THE RIDGE BUILDING OVER OHIO AND THE FLOW WILL EVENTUALLY BECOME SLIGHTLY OFFSHORE DUE TO A WK LAND BREEZE. SATELLITE AND RADAR SUGGEST THAT PLENTY OF WK LES BANDS CONTINUE ATTM...WHICH WILL REQUIRE LKLY POPS FOR THE SNOWBELTS THIS EVENING. HOWEVER...AS FLOW BACKS AND EVEN DRIER AIR MOVES INTO THE REGION...WILL BE ABLE TO CUT POPS TO SCT BY MIDNIGHT. CLDS SHOULD ALSO DIMINISH AS THE FLOW BACKS...ESPECIALLY OVER INLAND AREAS OF OHIO. THIS WILL ALLOW FOR DECENT RADIATIONAL COOLING OVERNIGHT...AND HAVE OPTED TO CUT BACK TEMPS TONIGHT WITH TEMPS IN THE 5-10 DEG RANGE. COULD POSSIBLY SEE TEMPS COLDER IF WINDS CAN DECOUPLE COMPLETELY. THIS WOULD BE MOST LIKELY SOUTHERN AREAS AS NEXT SYSTEM OVER THE UPR MS VLY WILL BE APPROACHING THE NRN AREAS LATE.

SATURDAY SHOULD BE GENERALLY QUIET DESPITE THE FACT THAT A WEAK TROUGH/COLD FNT WILL BE MOVING THRU THE AREA DURING THE DAY. THIS SYSTEM WILL LIKELY BE DRY...ALTHOUGH ENOUGH MOISTURE WILL REMAIN IN PLACE OVER THE NE AREAS TO WARRANT SMALL CHC POPS MAINLY ALONG THE LAKESHORE EAST OF CLE. WILL NOT BRING POPS INLAND MAINLY DUE TO THE FLOW BEING SWLY AHD OF THE FNT AND LITTLE MOISTURE TO WORK WITH OTHER THAN THAT FROM THE LAKE. FLOW TURNS NWLY BEHIND THE FRONT BUT MOISTURE IS SIGNIFICANTLY LACKING WITH LITTLE IF ANY DYNAMICS. WILL GO WITH CHC POPS IN THE SNOW BELTS SAT NIGHT...BUT DO NOT THINK THAT SNOW ACCUMULATIONS FROM THE SNOW SHOWERS WILL BE SIGNIFICANT DUE TO INVERSION BEING 4-5KFT.

BIG MODEL DIFFERENCES SUN AND SUN NIGHT WITH NEXT SYSTEM CURRENTLY STILL OVER CA. THIS SRN SYSTEM WILL TRY TO PHASE OVER THE PLAINS WITH A WEAKER NRN STREAM SYSTEM DIVING OUT OF CANADA. MDLS DIFFER ON THE TIMING...WITH THE ETA BEING SLOWER AND FARTHER SOUTH WHILE THE GFS IS A LITTLE FASTER AN N. THE ETA WOULD SUGGEST MUCH OF THE PCPN BEING SNOW...WHILE THE GFS WOULD SUGGEST A PERIOD OF SNOW MIXING WITH OR CHANGING OVER TO SNOW BY EVENING MOST AREAS. FCST FOR THIS TIME PERIOD QUITE COMPLEX NOT ONLY WITH PCPN TYPE...BUT ALSO WITH TRACK OF THE LOW AND TIMING OF PCPN. THE GFS TRACK N AND W OF OHIO WOULD SUGGEST PCPN SUN AND SUN EVENING...THEN THE AREA BECOMES DRY SLOTTED. HOWEVER...THE ETA TRACK ALONG I-70 AND SLOWER WOULD IMPLY THE PCPN STARTING LATER IN THE DAY ON SUN WITH MORE FROZEN PCPN OVER THE ENTIRE AREA. AM TRENDING SOMEWHAT TOWARD THE GFS FOR NOW...RECOGNIZING THAT THE ETA SOLN IS FEASIBLE AND KEEP AT LEAST A MIXTURE OF PCPN FOR THE ENTIRE AREA IN THE FCST. ALTHOUGH IT SEEMS NEARLY CERTAIN THAT THE ENTIRE AREA WILL SEE PCPN SUN OR SUN NIGHT (OR BOTH PERIODS) WITH STRONG UPR DYNAMICS...WITH THE MDL DIFFERENCES HAVE OPTED TO JUST KEEP LKLY POPS FOR BOTH PERIODS FOR NOW. REGARDLESS OF MDL SOLN...BOTH START THE PCPN OUT AS ALL SNOW AND HAVE FOLLOWED THIS IN THE FCST. WHERE IT STAYS SNOW THE LONGEST...2-4 INCHES IS POSSIBLE BEFORE THE CHANGEOVER OCCURS (IF IT DOES).

WILL NEED TO KEEP CHC POPS IN FOR MONDAY TO ACCT FOR MDL TIMING DIFFS. HOWEVER...IF THE GFS VERIFIES IT WILL BE MAINLY DRY MONDAY...ESPECIALLY WEST. IF THE ETA VERIFIES...POPS WILL NEED TO BE HIGHER MONDAY.

&&

.LONG TERM(TUE THROUGH FRI)... DESPITE THE SHORT TERM MODEL DIFFERENCES...THE MED RANGE MODELS ARE IN GOOD AGREEMENT IN THE EXTENDED...WHICH ALLOWS FOR RELATIVELY HIGH CONFIDENCE IN THE EXTENDED FCST. AFTER THE SUN/SUN NIGHT SYSTEM E... HIGH PRES WL BUILD INTO THE GREAT LAKES THRU FRIDAY. THE GFS SHOWS THAT COLD AIR WILL MOVE S OVER THE SRN LAKES MON NIGHT AND TUE WHICH MAY ALLOW FOR SOME MINOR LES THRU TUE. HOWEVER...OVERALL THE EXTENDED SHOULD BE VERY QUIET WX WITH TEMPS NR NORMAL WITH NO MAJOR COLD SPELLS. &&

.CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE.

&&

SHORT TERM...MRD LONG TERM...MRD AVIATION...DJB

$$



.SHORT TERM(TONIGHT THROUGH MON NIGHT)... DESPITE THE HIGH PRES RIDGE BUILDING INTO THE REGION...PLENTY OF LIGHT LAKE EFFECT SNOW SHOWERS CONTINUE IN THE SNOW BELTS. SNOW IS DIMINISHING UNDER NVA AND A LOWERING INVERSION SEEN PER TAMDAR DATA. FLOW WILL SLOWLY START TO BACK THIS EVENING IN RESPONSE TO THE RIDGE BUILDING OVER OHIO AND THE FLOW WILL EVENTUALLY BECOME SLIGHTLY OFFSHORE DUE TO A WK LAND BREEZE. SATELLITE AND RADAR SUGGEST THAT PLENTY OF WK LES BANDS CONTINUE ATTM...WHICH WILL REQUIRE LKLY POPS FOR THE SNOWBELTS THIS EVENING. HOWEVER...AS FLOW BACKS AND EVEN DRIER AIR MOVES INTO THE REGION...WILL BE ABLE TO CUT POPS TO SCT BY MIDNIGHT. CLDS SHOULD ALSO DIMINISH AS THE FLOW BACKS...ESPECIALLY OVER INLAND AREAS OF OHIO. THIS WILL ALLOW FOR DECENT RADIATIONAL COOLING OVERNIGHT...AND HAVE OPTED TO CUT BACK TEMPS TONIGHT WITH TEMPS IN THE 5-10 DEG RANGE. COULD POSSIBLY SEE TEMPS COLDER IF WINDS CAN DECOUPLE COMPLETELY. THIS WOULD BE MOST LIKELY SOUTHERN AREAS AS NEXT SYSTEM OVER THE UPR MS VLY WILL BE APPROACHING THE NRN AREAS LATE.

SATURDAY SHOULD BE GENERALLY QUIET DESPITE THE FACT THAT A WEAK TROUGH/COLD FNT WILL BE MOVING THRU THE AREA DURING THE DAY. THIS SYSTEM WILL LIKELY BE DRY...ALTHOUGH ENOUGH MOISTURE WILL REMAIN IN PLACE OVER THE NE AREAS TO WARRANT SMALL CHC POPS MAINLY ALONG THE LAKESHORE EAST OF CLE. WILL NOT BRING POPS INLAND MAINLY DUE TO THE FLOW BEING SWLY AHD OF THE FNT AND LITTLE MOISTURE TO WORK WITH OTHER THAN THAT FROM THE LAKE. FLOW TURNS NWLY BEHIND THE FRONT BUT MOISTURE IS SIGNIFICANTLY LACKING WITH LITTLE IF ANY DYNAMICS. WILL GO WITH CHC POPS IN THE SNOW BELTS SAT NIGHT...BUT DO NOT THINK THAT SNOW ACCUMULATIONS FROM THE SNOW SHOWERS WILL BE SIGNIFICANT DUE TO INVERSION BEING 4-5KFT.

BIG MODEL DIFFERENCES SUN AND SUN NIGHT WITH NEXT SYSTEM CURRENTLY STILL OVER CA. THIS SRN SYSTEM WILL TRY TO PHASE OVER THE PLAINS WITH A WEAKER NRN STREAM SYSTEM DIVING OUT OF CANADA. MDLS DIFFER ON THE TIMING...WITH THE ETA BEING SLOWER AND FARTHER SOUTH WHILE THE GFS IS A LITTLE FASTER AN N. THE ETA WOULD SUGGEST MUCH OF THE PCPN BEING SNOW...WHILE THE GFS WOULD SUGGEST A PERIOD OF SNOW MIXING WITH OR CHANGING OVER TO SNOW BY EVENING MOST AREAS. FCST FOR THIS TIME PERIOD QUITE COMPLEX NOT ONLY WITH PCPN TYPE...BUT ALSO WITH TRACK OF THE LOW AND TIMING OF PCPN. THE GFS TRACK N AND W OF OHIO WOULD SUGGEST PCPN SUN AND SUN EVENING...THEN THE AREA BECOMES DRY SLOTTED. HOWEVER...THE ETA TRACK ALONG I-70 AND SLOWER WOULD IMPLY THE PCPN STARTING LATER IN THE DAY ON SUN WITH MORE FROZEN PCPN OVER THE ENTIRE AREA. AM TRENDING SOMEWHAT TOWARD THE GFS FOR NOW...RECOGNIZING THAT THE ETA SOLN IS FEASIBLE AND KEEP AT LEAST A MIXTURE OF PCPN FOR THE ENTIRE AREA IN THE FCST. ALTHOUGH IT SEEMS NEARLY CERTAIN THAT THE ENTIRE AREA WILL SEE PCPN SUN OR SUN NIGHT (OR BOTH PERIODS) WITH STRONG UPR DYNAMICS...WITH THE MDL DIFFERENCES HAVE OPTED TO JUST KEEP LKLY POPS FOR BOTH PERIODS FOR NOW. REGARDLESS OF MDL SOLN...BOTH START THE PCPN OUT AS ALL SNOW AND HAVE FOLLOWED THIS IN THE FCST. WHERE IT STAYS SNOW THE LONGEST...2-4 INCHES IS POSSIBLE BEFORE THE CHANGEOVER OCCURS (IF IT DOES).

WILL NEED TO KEEP CHC POPS IN FOR MONDAY TO ACCT FOR MDL TIMING DIFFS. HOWEVER...IF THE GFS VERIFIES IT WILL BE MAINLY DRY MONDAY...ESPECIALLY WEST. IF THE ETA VERIFIES...POPS WILL NEED TO BE HIGHER MONDAY.

&&

.LONG TERM(TUE THROUGH FRI)... DESPITE THE SHORT TERM MODEL DIFFERENCES...THE MED RANGE MODELS ARE IN GOOD AGREEMENT IN THE EXTENDED...WHICH ALLOWS FOR RELATIVELY HIGH CONFIDENCE IN THE EXTENDED FCST. AFTER THE SUN/SUN NIGHT SYSTEM E... HIGH PRES WL BUILD INTO THE GREAT LAKES THRU FRIDAY. THE GFS SHOWS THAT COLD AIR WILL MOVE S OVER THE SRN LAKES MON NIGHT AND TUE WHICH MAY ALLOW FOR SOME MINOR LES THRU TUE. HOWEVER...OVERALL THE EXTENDED SHOULD BE VERY QUIET WX WITH TEMPS NR NORMAL WITH NO MAJOR COLD SPELLS. &&

.AVIATION (18Z-18Z)... LAKE EFFECT CLOUDS AND LIGHT SNOW SHOWERS WILL GRADUALLY DIMINISH THIS AFTERNOON AND EVENING AS THE LOW LEVEL TEMPERATURE INVERSION LOWERS AND THE WIND FLOW BACKS TO THE WEST AND DECREASES. FOR THE MOST PART VFR CONDITONS WILL PREVAIL. &&

.CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE.

&&

SHORT TERM...MRD LONG TERM...MRD AVIATION...LAPLANTE

$$



.DISCUSSION...

DAYS 1-2...

TEMPERATURES AND THE POTENTIAL FOR A THUNDERSTORM OR TWO SATURDAY AFTERNOON PROVIDE THE BIGGEST CHALLENGES FOR THE FORECAST THIS MORNING.

A VERY COMPLEX FLOW REGIME CHARACTERIZED BY AN ACTIVE SUBTROPICAL JET AND SPLIT FLOW IN THE EASTERN PACIFIC WILL CONTINUE FOR THE FORESEEABLE FUTURE WITH ONLY MINOR VARIATIONS. THE GFS APPEARED TO INITIALIZE FAIRLY WELL WITH SATELLITE AND AIRCRAFT OBSERVATIONS OVER THE EASTERN PACIFIC AND WAS FOLLOWED CLOSELY FOR THE GRIDS.

WIDESPREAD LIGHT RAIN LARGELY HAD ENDED ACROSS SOUTHWESTERN KANSAS BY 2 AM WITH PASSAGE OF A SHORT WAVE IN THE SUBTROPICAL FLOW, BUT WIDESPREAD STRATUS AND FOG RESTRICTING VISIBILITIES TO 1 TO 3 MILES CONTINUED. PROFILER WINDS IN THE LOWER LEVELS OF THE ATMOSPHERE HAVE BEEN VEERING WITH TIME, AND DOWNSLOPE FLOW SHOULD ERODE THE STRATUS FROM SOUTHWEST TO NORTHEAST DURING THE DAY. TIMING OF THE EROSION IS LESS THAN CERTAIN, AND MAXIMUM TEMPERATURES WILL BE HIGHLY DEPENDENT UPON HOW QUICKLY THE LOW CLOUDS EVAPORATE. ABUNDANT HIGH LEVEL TROPICAL MOISTURE ORIGINATING IN THE ITCZ WILL CONTINUE TO FLOW OVER THE CENTRAL AND SOUTHERN UNITED STATES IN THE VERY ACTIVE SUBTROPICAL JET, AND UNCERTAINTY ALSO EXISTS REGARDING OPAQUENESS OF THE CIRRIFORM CLOUDINESS THIS AFTERNOON. SOME INSOLATION WILL BE CONSUMED WITH EVAPORATION FROM THE MOIST GROUND, BUT TEMPERATURES STILL SHOULD WARM NICELY IN THE BEST DOWNSLOPE OVER FAR SOUTHWESTERN KANSAS.

A DRYLINE SHOULD EXTEND NEAR A LINE FROM LIBERAL TO SCOTT CITY BY MID AFTERNOON. TEMPERATURES AT H5 WILL BE NEAR -18 WITH LOW LEVEL DEWPOINTS IN THE MID 40S JUST AHEAD OF THE DRYLINE. THERE MAY BE JUST ENOUGH HEATING AND CONVERGENCE TO SUPPORT DEVELOPMENT OF A THUNDERSTORM OR TWO IN THE NARROW ZONE OF INSTABILITY IN ADVANCE OF THE DRYLINE. ANYTHING THAT DOES DEVELOP WILL MOVE INTO COOLER BOUNDARY LAYER AIR AND DIMINISH FAIRLY QUICKLY.

THE SHORT WAVE EVIDENT IN SATELLITE IMAGERY OVER SOUTHWESTERN UTAH EARLY THIS MORNING WILL RIPPLE OVER THE CENTRAL PLAINS TONIGHT, AND A SURFACE CYCLONE WILL MOVE ALONG THE BAROCLINIC ZONE ACROSS SOUTHERN NEBRASKA TO WESTERN IOWA BY SUNDAY MORNING. LOW LEVEL FLOW WILL BECOME MORE WESTERLY DURING THE NIGHT, AND SUFFICIENT GRADIENT SHOULD EXIST TO SUPPORT MIXING OF THE BOUNDARY LAYER OVERNIGHT. COOLER AIR WILL BEGIN TO SPREAD INTO NORTHERN KANSAS BEHIND THE SURFACE CYCLONE BY SUNDAY MORNING, AND TEMPERATURES SUNDAY MAY NOT BE QUITE AS WARM AS GUIDANCE VALUES SUGGEST IN THE NORTHERN ZONES. YET ANOTHER SHORT WAVE IN THE SUBTROPICAL BRANCH WILL APPROACH THE CENTRAL PLAINS SUNDAY NIGHT, AND THE NAM MODEL SQUEEZES OUT SOME PRECIPITATION. HOWEVER, A FAIRLY DEEP LAYER OF DRY AIR IN THE LOWER LEVELS OF THE ATMOSPHERE WILL EXIST, AND THE POTENTIAL FOR RECEIVING ANYTHING MORE THAN A SPRINKLE FROM MID LEVEL MOISTURE IS FAIRLY LOW.

AS TO TEMPERATURES, HAVE WARMED SATURDAY SIGNIFICANTLY AS MENTIONED ABOVE. OTHERWISE, HAVE WARMED THE PREVIOUS FORECAST ONLY SLIGHTLY.

DAYS 3-7... FORECAST CHALLENGES THIS EXTENDED PERIOD ARE CHANCES AND TYPE OF PRECIPITATION FROM TUESDAY INTO THURSDAY AND HIGH TEMPERATURES. AS UPPER LEVEL SYSTEM APPROACHES AREA AND SPITS OUT SEVERAL MINOR SHORTWAVES THIS WILL BRING INCREASING CHANCES OF PRECIPITATION. COOLER UPSLOPE FLOW WILL PREVAIL ON MONDAY AND TUESDAY WITH A MODIFIED ARCTIC SURGE COMING INTO WESTERN KANSAS BY WEDNESDAY MORNING. BY WEDNESDAY LOOKS LIKE MOST PRECIP WILL CHANGE TO ALL SNOW WITH COOLER LAYER TEMPS AROUND OR BELOW -2C AT 850MB. CLOUDS WILL LIKELY PREVAIL AS WELL FROM MONDAY THROUGH THURSDAY WITH COLD AIR AND UPSLOPE FLOW WITH OVER RUNNING CLOUDINESS ALSO WITH UPPER WAVE. HIGHS SHOULD ONLY REACH THE LOW TO MID 30S WEDNESDAY AND THURSDAY WITH SOME MODIFICATION ON FRIDAY INTO THE WEEKEND. NO MAJOR CHANGES WERE MADE TO GRIDS EXCEPT TO TWEAK DEWPOINTS AND WINDS SLIGHTLY.

&&

.PRELIMINARY POINT TEMPS/POPS... DDC 61 39 63 31 / 05 05 00 00 GCK 64 36 62 29 / 10 10 00 00 EHA 71 34 63 32 / 00 00 00 00 LBL 69 39 64 32 / 10 05 00 00 HYS 54 39 59 27 / 10 10 00 00 P28 61 44 66 38 / 10 05 05 10

&&

.DDC WATCHES/WARNINGS/ADVISORIES... .KS...NONE.

&&

$$

01/KRUSE



.SHORT TERM (TODAY THOUGH TONIGHT): WATER VAPOR LOOP SHOWS A TROUGH ANCHORED ACROSS EASTERN CANADA SOUTHEAST INTO THE NORTHERN ATLANTIC OCEAN. A WAVE EMBEDDED WITHIN THE MEAN FLOW ACROSS THE EASTERN GREAT LAKES CONTINUES TO DROP SOUTHEAST TOWARDS THE NORTHERN MID ATLANTIC. ACARS 400-250MB WIND OBSERVATIONS REVEAL DUAL 140-150KT UPPER LEVEL JETS...ONE STRETCHES FROM THE UPPER MIDWEST INTO THE MID ATLANTIC...WHILE THE SECOND SPANS FROM THE FOUR CORNERS REGION EAST SOUTHEAST INTO THE SOUTHEAST CONUS. 04Z SURFACE ANALYSIS PLACES A 1023MB CYCLONE OVER NORTHWEST NORTH CAROLINA...ALONG A NEARLY STATIONARY BOUNDARY WHICH STRETCHES FROM THE NORTHERN PLAINS EAST THROUGH THE MID ATLANTIC. DUAL ANTICYCLONES DOMINATE THE MIDWEST AND GULF COAST STATES RESPECTFULLY.

WARM ADVECTION FROM APPROACHING SHORTWAVE IS SUPPORTING THE DEVELOPMENT OF SCATTERED CLOUDS ACROSS THE APPALACHIANS UNDERNEATH THE INVERSION. EXPECTING THIS PROCESS TO SUPPORT A FEW CLOUDS MAINLY BEFORE SUNRISE...WHICH SHOULD DISSIPATE WITH THE PASSAGE OF THE FAST MOVING WAVE. RISING HEIGHTS BEHIND THIS WAVE WILL SUPPORT THE JET AXIS TO PROPAGATE NORTHEAST...ALLOWING A FEW HIGHER LEVEL CLOUDS INTO THE REGION FROM THE SOUTHWEST...ESPECIALLY DURING THE LATER PORTION OF THE AFTERNOON.

HEIGHT RISES WILL ALSO SUPPORT SURFACE HIGH PRESSURE BUILDING INTO THE MID ATLANTIC. THIS WILL DECREASE THE PRESSURE GRADIENT AND PROVIDE FOR LIGHT WINDS. BOTH THE ETA AND GFS INDICATE LOW LEVEL TEMPERATURES WILL RISE BY THE AFTERNOON...WHICH WILL ALLOW TEMPERATURES TO BOUNCE BACK TO THE UPPER 30S AND LOWER 40S.

AS THE NEXT SYSTEM ORGANIZES ACROSS THE MIDWEST AND THE MIDLEVEL RIDGE APPROACHES THE OHIO VALLEY OVERNIGHT...HIGHER AND MID LEVEL CLOUDS WILL CONTINUE TO STREAM INTO THE REGION. THE INCREASE IN CLOUDS AND MOISTURE WILL SUPPORT A MORE GRADUAL TEMPERATURE FALL THAN SEEN DURING THE PAST SEVERAL NIGHTS. WITH THE SURFACE RIDGE AXIS OVER THE REGION...LIGHT WINDS WILL PERSIST.

&&

.AVIATION: LIGHT WINDS...NO VISIBILITY/CEILING RESTRICTIONS ANTICIPATED DURING THE CURRENT VALID TAF CYCLE. UPPER LEVEL CLOUDS WILL GRADUALLY INCREASE DURING THE EVENING AND LOWER INTO THE MID LEVELS AS THE NIGHT PROGRESSES. OTHERWISE...SCATTERED CLOUDS NEAR 4KFT MAY DEVELOP ALONG THE APPALACHIANS AND MOVE EASTWARD TOWARDS THE BAY MAINLY DURING THE PRE-SUNRISE HOURS.

&& .MARINE: LOOSENING PRESSURE GRADIENT HAS ALLOWED WINDS TO RELAX ENOUGH TO DROP THE SMALL CRAFT ADVISORY. LIGHTER WINDS WILL BE THE RULE TODAY AND TONIGHT. WATER LEVELS ARE CURRENTLY RUNNING ABOUT A FOOT BELOW PREDICTED VALUES DUE TO THE PERSISTENT NORTHWEST FLOW...BUT SHOULD GRADUALLY RECOVER TODAY.

&&

.LONG TERM... GDNC CONSISTENT ON FCSTG WINTER STORM SUN-SUN NGT...THEN SOLNS DIVERGE MON. NAM APPEARS SUPERIOR DUE TO ITS RESOLUTION AND SFC TERRAIN.

RDGG SFC-H8 EASES OFF COAST DURING DAY SUN. STRONG H8 WAA PRSNT...W/ A 40-50 KT LLJ. ZNL FLOW ALOFT...SO OVERRUNNING WL BE MAIN PCPN TRIGGER. SFC LOPRES ENTERS LWR OHIO VLY. ALTHO TIMING SLGTLY DIFF... INGREDIENTS AVBL FOR MEASURABLE PCPN DVLPG SUNDAY...INCL FGEN FORCING. INCREASED POPS TO CAT IN THE W...KEPT IT AT CHC FOR DC/BALT METRO AREAS. KEPT TEMPS NEAR NAM VALUES AS AMS DRY...AND EVAP COOLING WL INHIBIT TEMPS.

STRONGEST ISENTROPIC LIFT SUN NGT. HWVR...AM CONCERNED THAT MDL BIAS OF ERODING COLD AIR TOO QUICKLY COMES INTO PLAY. THO IT WONT HV MUCH OPPORTUNITY TO SET UP...HIPRES OVR NEW ENGLND FVRBLY POSITIONED. WET BULB TEMPS SHUD BE LOW. AT THE SAME TIME...WAA H8-7 LEADS TO MELTING LYR IN MDL PROFILES AFTR MIDNGT...SPCLY IN S/SWRN CWFA. WL GO FOR SNW IN THE EVNG...THEN TREND TWD MIX AS WARM LYR MAKES IT INTERESTING. THUS...A TRICKY TYPE FCST. IF IT WERE JUST SNW... PARTS OF CWFA WUD THREATEN WATCH CRITERIA. WL HOLD OFF ONE MORE CYCLE DUE TO SLEET POTL DECREASING ACCUMS. BASED ON 12Z CYCLE...DAY SHIFT WL NEED TO CONSIDER WATCH...SPCLY FOR PTMC HIGHLANDS AND NRN MD.

NAM DOES A MUCH BETTER JOB OF HOLDING ONTO COLD AIR THAN GFS MON...WHICH MAKES IT A PREFERRED SOLN. W/ CLDS AND AN ELY COMPONENT TO THE WND...CANNOT SEE TEMPS RISING TO 55-60. ALL PCPN WL CHG OVR TO A COLD RAIN...MRNG S...AND MIDDAY IN THE N. DONT THINK THERE WL BE MUCH QPF BY AFTN THO.

LOPRES MVS OFFSHR AND STRENGTHENS. CWFA WL BE IN NWLY FLOW...AND SLOWLY WL DRY OUT. POPS TRIMMED THRU SHC MON NGT...AND DRY WX FOR TUE. ONCE AGN...NO CHGS TO DAY 5-7.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE.

&&

$$

SHORT TERM/AVIATION/MARINE FORECASTER: ROGOWSKI LONG TERM FORECASTER: HTS



.AVIATION (06Z-06Z)... HIGH PRESSURE CONTINES TO BUILD ACROSS THE LOWER LAKES. A FEW LIGHT SNOW SHOWERS NW PA AND A FEW LINGERING FLURRIES ACROSS NE AND NORTH CENTRAL OHIO ARE THE ONLY WEATHER ACROSS THE FOREAST AREA AT THIS TIME AND THAT WILL GRADUALLY END FROM THE WEST THIS MORNING.

CLEARING LINE NOW INTO TOLEDO AND MOVING EAST AT APPROXIMATELY 10-15 KNOTS. EXPECT CLOUDS TO SCATTER OUT FROM THE WEST THIS MORNING AS HIGH SPREADS EAST.

BY END OF PD A WARM FRONT WILL MOVE INTO MID MISSISSIPPI VALLEY SPREADING A MID LEVEL DECK ACROSS THE WESTERN AND CENTRAL PORTIONS OF THE FORECAST AREA. &&

.UPDATED SHORT TERM (TONIGHT)... CLOUDS HOLDING TOUGH ACROSS MUCH OF THE AREA TNGT ALTHOUGH SAT LOOP SHOWS THEY ARE CLEARLY ON THEIR WAY OUT. FOR NOW WILL REWORD ZONES TO ACCOUNT FOR CLOUDS EARLY WITH THE CLEARING REACHING THE AREA EITHER AFTER MIDNIGHT OR LATE DEPENDING ON LOCATION. CLOUDS DID BREAK IN THE EAST BUT LOOKS LIKE THEY WILL FILL BACK IN DURG THE NEXT FEW HOURS SO WL JUST GO WITH THE ABV CLRG TREND. NO MAJ CHG IN FCST LOWS ATTM. IF CLOUDS DO CLR OUT WOULD XPC FCST TO BE REACHED EASILY GVN VERY LOW DWPTS &&

.PREVIOUS SHORT TERM(TONIGHT THROUGH MON NIGHT)... DESPITE THE HIGH PRES RIDGE BUILDING INTO THE REGION...PLENTY OF LIGHT LAKE EFFECT SNOW SHOWERS CONTINUE IN THE SNOW BELTS. SNOW IS DIMINISHING UNDER NVA AND A LOWERING INVERSION SEEN PER TAMDAR DATA. FLOW WILL SLOWLY START TO BACK THIS EVENING IN RESPONSE TO THE RIDGE BUILDING OVER OHIO AND THE FLOW WILL EVENTUALLY BECOME SLIGHTLY OFFSHORE DUE TO A WK LAND BREEZE. SATELLITE AND RADAR SUGGEST THAT PLENTY OF WK LES BANDS CONTINUE ATTM...WHICH WILL REQUIRE LKLY POPS FOR THE SNOWBELTS THIS EVENING. HOWEVER...AS FLOW BACKS AND EVEN DRIER AIR MOVES INTO THE REGION...WILL BE ABLE TO CUT POPS TO SCT BY MIDNIGHT. CLDS SHOULD ALSO DIMINISH AS THE FLOW BACKS...ESPECIALLY OVER INLAND AREAS OF OHIO. THIS WILL ALLOW FOR DECENT RADIATIONAL COOLING OVERNIGHT...AND HAVE OPTED TO CUT BACK TEMPS TONIGHT WITH TEMPS IN THE 5-10 DEG RANGE. COULD POSSIBLY SEE TEMPS COLDER IF WINDS CAN DECOUPLE COMPLETELY. THIS WOULD BE MOST LIKELY SOUTHERN AREAS AS NEXT SYSTEM OVER THE UPR MS VLY WILL BE APPROACHING THE NRN AREAS LATE.

SATURDAY SHOULD BE GENERALLY QUIET DESPITE THE FACT THAT A WEAK TROUGH/COLD FNT WILL BE MOVING THRU THE AREA DURING THE DAY. THIS SYSTEM WILL LIKELY BE DRY...ALTHOUGH ENOUGH MOISTURE WILL REMAIN IN PLACE OVER THE NE AREAS TO WARRANT SMALL CHC POPS MAINLY ALONG THE LAKESHORE EAST OF CLE. WILL NOT BRING POPS INLAND MAINLY DUE TO THE FLOW BEING SWLY AHD OF THE FNT AND LITTLE MOISTURE TO WORK WITH OTHER THAN THAT FROM THE LAKE. FLOW TURNS NWLY BEHIND THE FRONT BUT MOISTURE IS SIGNIFICANTLY LACKING WITH LITTLE IF ANY DYNAMICS. WILL GO WITH CHC POPS IN THE SNOW BELTS SAT NIGHT...BUT DO NOT THINK THAT SNOW ACCUMULATIONS FROM THE SNOW SHOWERS WILL BE SIGNIFICANT DUE TO INVERSION BEING 4-5KFT.

BIG MODEL DIFFERENCES SUN AND SUN NIGHT WITH NEXT SYSTEM CURRENTLY STILL OVER CA. THIS SRN SYSTEM WILL TRY TO PHASE OVER THE PLAINS WITH A WEAKER NRN STREAM SYSTEM DIVING OUT OF CANADA. MDLS DIFFER ON THE TIMING...WITH THE ETA BEING SLOWER AND FARTHER SOUTH WHILE THE GFS IS A LITTLE FASTER AN N. THE ETA WOULD SUGGEST MUCH OF THE PCPN BEING SNOW...WHILE THE GFS WOULD SUGGEST A PERIOD OF SNOW MIXING WITH OR CHANGING OVER TO SNOW BY EVENING MOST AREAS. FCST FOR THIS TIME PERIOD QUITE COMPLEX NOT ONLY WITH PCPN TYPE...BUT ALSO WITH TRACK OF THE LOW AND TIMING OF PCPN. THE GFS TRACK N AND W OF OHIO WOULD SUGGEST PCPN SUN AND SUN EVENING...THEN THE AREA BECOMES DRY SLOTTED. HOWEVER...THE ETA TRACK ALONG I-70 AND SLOWER WOULD IMPLY THE PCPN STARTING LATER IN THE DAY ON SUN WITH MORE FROZEN PCPN OVER THE ENTIRE AREA. AM TRENDING SOMEWHAT TOWARD THE GFS FOR NOW...RECOGNIZING THAT THE ETA SOLN IS FEASIBLE AND KEEP AT LEAST A MIXTURE OF PCPN FOR THE ENTIRE AREA IN THE FCST. ALTHOUGH IT SEEMS NEARLY CERTAIN THAT THE ENTIRE AREA WILL SEE PCPN SUN OR SUN NIGHT (OR BOTH PERIODS) WITH STRONG UPR DYNAMICS...WITH THE MDL DIFFERENCES HAVE OPTED TO JUST KEEP LKLY POPS FOR BOTH PERIODS FOR NOW. REGARDLESS OF MDL SOLN...BOTH START THE PCPN OUT AS ALL SNOW AND HAVE FOLLOWED THIS IN THE FCST. WHERE IT STAYS SNOW THE LONGEST...2-4 INCHES IS POSSIBLE BEFORE THE CHANGEOVER OCCURS (IF IT DOES).

WILL NEED TO KEEP CHC POPS IN FOR MONDAY TO ACCT FOR MDL TIMING DIFFS. HOWEVER...IF THE GFS VERIFIES IT WILL BE MAINLY DRY MONDAY...ESPECIALLY WEST. IF THE ETA VERIFIES...POPS WILL NEED TO BE HIGHER MONDAY.

&&

.LONG TERM(TUE THROUGH FRI)... DESPITE THE SHORT TERM MODEL DIFFERENCES...THE MED RANGE MODELS ARE IN GOOD AGREEMENT IN THE EXTENDED...WHICH ALLOWS FOR RELATIVELY HIGH CONFIDENCE IN THE EXTENDED FCST. AFTER THE SUN/SUN NIGHT SYSTEM E... HIGH PRES WL BUILD INTO THE GREAT LAKES THRU FRIDAY. THE GFS SHOWS THAT COLD AIR WILL MOVE S OVER THE SRN LAKES MON NIGHT AND TUE WHICH MAY ALLOW FOR SOME MINOR LES THRU TUE. HOWEVER...OVERALL THE EXTENDED SHOULD BE VERY QUIET WX WITH TEMPS NR NORMAL WITH NO MAJOR COLD SPELLS. &&

.CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE.

&& SHORT TERM UPDATE...TK PRVS SHORT TERM...MRD LONG TERM...MRD AVIATION...DJB

$$



ONLY MINOR TWEAKS MADE TO WINDS AND SKY GRIDS. TEMPS LOOK FINE. 12Z ETA SUGGESTING A FASTER TRANSITION TO MIXED PRECIP SUNDAY EVENING THAN PREVIOUSLY EXPECTED ACROSS MOST OF THE CWA. STILL POSSIBILITY FOR MARGINAL WARNING CRITERIA SNOWS OVER NERN MD. MORE ON THIS IN THE AFTERNOON.

ROSA

PREVIOUS AFD...

.SHORT TERM (TODAY THOUGH TONIGHT): WATER VAPOR LOOP SHOWS A TROUGH ANCHORED ACROSS EASTERN CANADA SOUTHEAST INTO THE NORTHERN ATLANTIC OCEAN. A WAVE EMBEDDED WITHIN THE MEAN FLOW ACROSS THE EASTERN GREAT LAKES CONTINUES TO DROP SOUTHEAST TOWARDS THE NORTHERN MID ATLANTIC. ACARS 400-250MB WIND OBSERVATIONS REVEAL DUAL 140-150KT UPPER LEVEL JETS...ONE STRETCHES FROM THE UPPER MIDWEST INTO THE MID ATLANTIC...WHILE THE SECOND SPANS FROM THE FOUR CORNERS REGION EAST SOUTHEAST INTO THE SOUTHEAST CONUS. 04Z SURFACE ANALYSIS PLACES A 1023MB CYCLONE OVER NORTHWEST NORTH CAROLINA...ALONG A NEARLY STATIONARY BOUNDARY WHICH STRETCHES FROM THE NORTHERN PLAINS EAST THROUGH THE MID ATLANTIC. DUAL ANTICYCLONES DOMINATE THE MIDWEST AND GULF COAST STATES RESPECTFULLY.

WARM ADVECTION FROM APPROACHING SHORTWAVE IS SUPPORTING THE DEVELOPMENT OF SCATTERED CLOUDS ACROSS THE APPALACHIANS UNDERNEATH THE INVERSION. EXPECTING THIS PROCESS TO SUPPORT A FEW CLOUDS MAINLY BEFORE SUNRISE...WHICH SHOULD DISSIPATE WITH THE PASSAGE OF THE FAST MOVING WAVE. RISING HEIGHTS BEHIND THIS WAVE WILL SUPPORT THE JET AXIS TO PROPAGATE NORTHEAST...ALLOWING A FEW HIGHER LEVEL CLOUDS INTO THE REGION FROM THE SOUTHWEST...ESPECIALLY DURING THE LATER PORTION OF THE AFTERNOON.

HEIGHT RISES WILL ALSO SUPPORT SURFACE HIGH PRESSURE BUILDING INTO THE MID ATLANTIC. THIS WILL DECREASE THE PRESSURE GRADIENT AND PROVIDE FOR LIGHT WINDS. BOTH THE ETA AND GFS INDICATE LOW LEVEL TEMPERATURES WILL RISE BY THE AFTERNOON...WHICH WILL ALLOW TEMPERATURES TO BOUNCE BACK TO THE UPPER 30S AND LOWER 40S.

AS THE NEXT SYSTEM ORGANIZES ACROSS THE MIDWEST AND THE MIDLEVEL RIDGE APPROACHES THE OHIO VALLEY OVERNIGHT...HIGHER AND MID LEVEL CLOUDS WILL CONTINUE TO STREAM INTO THE REGION. THE INCREASE IN CLOUDS AND MOISTURE WILL SUPPORT A MORE GRADUAL TEMPERATURE FALL THAN SEEN DURING THE PAST SEVERAL NIGHTS. WITH THE SURFACE RIDGE AXIS OVER THE REGION...LIGHT WINDS WILL PERSIST.

&&

.AVIATION: LIGHT WINDS...NO VISIBILITY/CEILING RESTRICTIONS ANTICIPATED DURING THE CURRENT VALID TAF CYCLE. UPPER LEVEL CLOUDS WILL GRADUALLY INCREASE DURING THE EVENING AND LOWER INTO THE MID LEVELS AS THE NIGHT PROGRESSES. OTHERWISE...SCATTERED CLOUDS NEAR 4KFT MAY DEVELOP ALONG THE APPALACHIANS AND MOVE EASTWARD TOWARDS THE BAY MAINLY DURING THE PRE-SUNRISE HOURS.

&& .MARINE: LOOSENING PRESSURE GRADIENT HAS ALLOWED WINDS TO RELAX ENOUGH TO DROP THE SMALL CRAFT ADVISORY. LIGHTER WINDS WILL BE THE RULE TODAY AND TONIGHT. WATER LEVELS ARE CURRENTLY RUNNING ABOUT A FOOT BELOW PREDICTED VALUES DUE TO THE PERSISTENT NORTHWEST FLOW...BUT SHOULD GRADUALLY RECOVER TODAY.

&&

.LONG TERM... GDNC CONSISTENT ON FCSTG WINTER STORM SUN-SUN NGT...THEN SOLNS DIVERGE MON. NAM APPEARS SUPERIOR DUE TO ITS RESOLUTION AND SFC TERRAIN.

RDGG SFC-H8 EASES OFF COAST DURING DAY SUN. STRONG H8 WAA PRSNT...W/ A 40-50 KT LLJ. ZNL FLOW ALOFT...SO OVERRUNNING WL BE MAIN PCPN TRIGGER. SFC LOPRES ENTERS LWR OHIO VLY. ALTHO TIMING SLGTLY DIFF... INGREDIENTS AVBL FOR MEASURABLE PCPN DVLPG SUNDAY...INCL FGEN FORCING. INCREASED POPS TO CAT IN THE W...KEPT IT AT CHC FOR DC/BALT METRO AREAS. KEPT TEMPS NEAR NAM VALUES AS AMS DRY...AND EVAP COOLING WL INHIBIT TEMPS.

STRONGEST ISENTROPIC LIFT SUN NGT. HWVR...AM CONCERNED THAT MDL BIAS OF ERODING COLD AIR TOO QUICKLY COMES INTO PLAY. THO IT WONT HV MUCH OPPORTUNITY TO SET UP...HIPRES OVR NEW ENGLND FVRBLY POSITIONED. WET BULB TEMPS SHUD BE LOW. AT THE SAME TIME...WAA H8-7 LEADS TO MELTING LYR IN MDL PROFILES AFTR MIDNGT...SPCLY IN S/SWRN CWFA. WL GO FOR SNW IN THE EVNG...THEN TREND TWD MIX AS WARM LYR MAKES IT INTERESTING. THUS...A TRICKY TYPE FCST. IF IT WERE JUST SNW... PARTS OF CWFA WUD THREATEN WATCH CRITERIA. WL HOLD OFF ONE MORE CYCLE DUE TO SLEET POTL DECREASING ACCUMS. BASED ON 12Z CYCLE...DAY SHIFT WL NEED TO CONSIDER WATCH...SPCLY FOR PTMC HIGHLANDS AND NRN MD.

NAM DOES A MUCH BETTER JOB OF HOLDING ONTO COLD AIR THAN GFS MON...WHICH MAKES IT A PREFERRED SOLN. W/ CLDS AND AN ELY COMPONENT TO THE WND...CANNOT SEE TEMPS RISING TO 55-60. ALL PCPN WL CHG OVR TO A COLD RAIN...MRNG S...AND MIDDAY IN THE N. DONT THINK THERE WL BE MUCH QPF BY AFTN THO.

LOPRES MVS OFFSHR AND STRENGTHENS. CWFA WL BE IN NWLY FLOW...AND SLOWLY WL DRY OUT. POPS TRIMMED THRU SHC MON NGT...AND DRY WX FOR TUE. ONCE AGN...NO CHGS TO DAY 5-7.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE.

&&

$$

SHORT TERM/AVIATION/MARINE FORECASTER: ROGOWSKI LONG TERM FORECASTER: HTS