Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/19/12
AREA FORECAST DISCUSSION
NWS MIAMI FL
1000 PM EDT TUE SEP 18 2012
.UPDATE...THE HRRR HAD A GOOD HANDLE ON BRINGING GULF ACTIVITY
ACROSS THE EAST COAST METRO, JUST A COUPLE HR EARLY. THERE APPEARS
TO BE A BROAD LOW ALOFT JUST OFF THE FT. MYERS/NAPLES COAST WITH
MOVE CONVECTION, THOUGHT NOT AS ROBUST, TRAILING THIS FEATURE. THE
LATEST HRRR ACTUALLY SHOWS THIS ACTIVITY MOVING EAST AND
DEVELOPING FURTHER OVERNIGHT AND MOVING INTO THE EAST COAST METRO
WITH MORE TSTORMS WELL AFTER MIDNIGHT. THE MIAMI SOUNDING THIS EVENING
SHOWS HIGH MOISTURE WITH A PWAT OF 2.12 INCHES IN AN UNSTABLE
ATMOSPHERE WITH CAPE OF AROUND 3000 J/KG, LI -6.4C...AND WITH
SHORTWAVE ENERGY MOVING IN FROM THE GULF THE AFOREMENTIONED HRRR
SOLUTION LOOKS PLAUSIBLE. SO WITH THIS POTENTIAL, WILL KEEP THE
GOING FORECAST OF CHANCE OF TSTORMS EAST COAST AND LIKELY GULF
COAST GOING. /GREGORIA
&&
.PREV DISCUSSION... /ISSUED 750 PM EDT TUE SEP 18 2012/
AVIATION...
DEEP MOISTURE ACROSS THE SOUTHEASTERN GULF OF MEXICO WILL CONTINUE
TO STREAM INTO THE SOUTH FLORIDA PENINSULA OVER THE NEXT 24 HOURS.
THIS WILL ALLOW INTERMITTENT SHRAS/TSRAS TO AFFECT ALL TAF SITES
THROUGH THE PERIOD. A PRE-FRONTAL TROUGH COMBINED WITH POCKETS OF
DECENT UVV/S WILL ENHANCE AREAS OF TSRAS THROUGH THE OVERNIGHT
PERIOD AND INTO THE MORNING HOURS SO KEPT VCSH MENTION THROUGH
THE 06Z-08Z TIME FRAME. BY TOMORROW AFTERNOON...BEST CONCENTRATION
OF SHRAS AND TSRAS SHOULD BE CONFINED TO THE EAST COAST TERMINALS
WITH WEAKER SOUTHWEST STEERING FLOW. THE FLOW WILL THEN TURN MORE
TO THE NORTHWEST AS THE FRONT APPROACHES.
PREV DISCUSSION... /ISSUED 509 PM EDT TUE SEP 18 2012/
UPDATE...LINE OF SHOWERS AND THUNDERSTORMS OVER THE GULF OF
MEXICO IS MOVING TOWARDS THE GULF COAST/NAPLES AREA. THIS LINE
WILL IMPACT THIS AREA THROUGH EARLY EVENING. THE LINE IS MOVING
STEADILY EASTWARD...AND LATEST HRRR SHOWS THIS CONVECTION TRACKING
ACROSS SOUTH FLORIDA TONIGHT, REACHING THE EAST COAST METRO AREA
AT AROUND MIDNIGHT. GIVEN THE AMPLIFIED TROUGH AND INCOMING
SHORTWAVE, THIS SEEMS PLAUSIBLE. AS SUCH, HAVE UPDATED THE
FORECAST TO ACCOUNT FOR LIKELY ACTIVITY GULF COAST AND A CHANCE
OF THUNDERSTORMS EAST COAST METRO TONIGHT...AS THERE IS THE
POTENTIAL FOR THIS LINE OF STORMS TO MOVE INTO THE AREA TONIGHT.
IN OTHER WORDS, NOT OUR TYPICAL DIURNAL CYCLE. LIGHTNING/HEAVY
RAINS MAIN IMPACTS, BUT LOCALIZED WIND GUSTS OF 40-50 MPH
POSSIBLE. /GREGORIA
PREV DISCUSSION... /ISSUED 210 PM EDT TUE SEP 18 2012/
DISCUSSION...AN EXTREMELY COMPLEX WEATHER PATTERN IS DEVELOPING
ACROSS THE U.S. WHICH WILL HAVE ITS AFFECTS ON SOUTH FLORIDA. A MID
LEVEL TROUGH OVER THE GULF COAST NEAR THE LOWER MISSISSIPPI VALLEY
THIS MORNING IS BECOMING ABSORBED INTO LARGER SCALE TROUGH DEEPENING
INTO THE SOUTHEAST STATES WITH ITS ASSOCIATED COLD FRONT MOVING INTO
THE FL PANHANDLE. THIS SYSTEM WILL RAPIDLY LIFT TO THE NORTHEAST
TONIGHT AND WEDNESDAY AS ANOTHER TROUGH ROTATES THROUGH THE BASE OF
THE MAIN TROUGH AXIS AND MASSIVE RIDGES BUILD OVER THE WESTERN U.S.
AND THE WESTERN ATLANTIC. THIS IN TURN WILL ALLOW THE COLD FRONT TO
MOVE INTO NORTH CENTRAL FLORIDA AND STALL AS THE PENINSULA SOMEWHAT
BECOMES SANDWICHED IN BETWEEN ALL OF THESE SYSTEMS. THIS EVOLVING
SITUATION WILL ALSO RESULT IN ANOTHER DAY ON WEDNESDAY OF DEEP
SOUTHWESTERLY FLOW AND KEEP THE HIGHEST POPS OVER THE INTERIOR AND
EAST COAST METRO REGIONS.
ON THURSDAY, THE RIDGE OUT WEST WILL CONTINUE TO AMPLIFY WITH THE
MAIN ENERGY OF THE EASTERN TROUGH CONTINUING TO LIFT TO THE
NORTHEAST. THIS HAPPENS DUE TO THE ATLANTIC RIDGE SHIFTING WEST AS A
LARGE MID LEVEL TROUGH MOVES INTO THE CENTRAL ATLANTIC. REACTING TO
THIS WILL BE THE SFC RIDGE SHIFTING BACK NORTH PLACING SOUTH FLORIDA
IN A LOW LEVEL SOUTHEAST FLOW WITH WEAKER STEERING ALOFT. THE END
RESULT WILL BE SEA BREEZE DRIVEN ACTIVITY MOVING VERY LITTLE BUT
TENDING TO FAVOR THE INTERIOR SECTIONS. ALL IN ALL IN THE SHORT
TERM, MAJOR WEATHER SYSTEMS WILL BE FAR REMOVED FROM SOUTH FLORIDA
BUT PLACING US IN A FAVORABLE LOCATION FOR DAILY AFTERNOON/EVENING
SHOWERS AND THUNDERSTORMS.
IN THE EXTENDED PERIOD INTO THE WEEKEND AND EARLY NEXT WEEK, THE
WEATHER PATTERN WILL CHANGE VERY SLOWLY AND IT APPEARS THAT SOUTH
FLORIDA WILL BE UNDER THE INFLUENCE OF SEVERAL DAYS WITH SEA BREEZE
INTERACTION VARIETY THUNDERSTORM ACTIVITY. SO THE MAIN AREA OF
CONCERN FOR RAINFALL FROM THURSDAY INTO EARLY NEXT WEEK WILL BE THE
FAR WESTERN SUBURBS OF BOTH COASTS AND ANY LOCATION OVER THE
INTERIOR.
AVIATION...A RIDGE OF HIGH PRESSURE AT THE SURFACE AND ALOFT
SOUTHEAST OF THE AREA AND OVER THE FLA STRAITS WILL PERSIST THROUGH
THE PERIOD. WINDS WILL BE SOUTHERLY < 10 KTS THEN BECOME SSW TO SW
AND INCREASE 10 TO 15 KNOTS AS THE DAY PROGRESSES. NO E COAST SEA
BREEZE EXPECTED. WITH THE SSW-SW WIND FLOW...SOME VCSH AT KAPF WITH
VCTS EXPECTED AT ALL TERMINALS AFT 17Z. POSSIBLE THAT SOME MVFR
VSBY/CIG AT ANY ONE TERMINAL IF A TSRA MOVES OVER LATER TODAY.
MARINE...OUTSIDE OF SHOWERS AND THUNDERSTORMS, BOATING CONDITIONS
WILL BE TRANQUIL WITH A SOUTH TO SOUTHWEST WIND LESS THAN 15 KNOTS
THROUGH WEDNESDAY BECOMING SOUTHEASTERLY AT LESS THAN 15 KNOTS
THURSDAY INTO THE WEEKEND. THIS WILL RESULT IN SEAS OF LESS THAN 4 FEET.
FIRE WEATHER...NO PROBLEMS OR CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 89 75 87 / 40 50 30 40
FORT LAUDERDALE 77 90 76 87 / 40 40 20 40
MIAMI 77 90 78 88 / 40 40 20 40
NAPLES 76 89 74 89 / 60 30 20 40
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MIAMI FL
750 PM EDT TUE SEP 18 2012
.AVIATION...
DEEP MOISTURE ACROSS THE SOUTHEASTERN GULF OF MEXICO WILL CONTINUE
TO STREAM INTO THE SOUTH FLORIDA PENINSULA OVER THE NEXT 24 HOURS.
THIS WILL ALLOW INTERMITTENT SHRAS/TSRAS TO AFFECT ALL TAF SITES
THROUGH THE PERIOD. A PRE-FRONTAL TROUGH COMBINED WITH POCKETS OF
DECENT UVV/S WILL ENHANCE AREAS OF TSRAS THROUGH THE OVERNIGHT
PERIOD AND INTO THE MORNING HOURS SO KEPT VCSH MENTION THROUGH
THE 06Z-08Z TIME FRAME. BY TOMORROW AFTERNOON...BEST CONCENTRATION
OF SHRAS AND TSRAS SHOULD BE CONFINED TO THE EAST COAST TERMINALS
WITH WEAKER SOUTHWEST STEERING FLOW. THE FLOW WILL THEN TURN MORE
TO THE NORTHWEST AS THE FRONT APPROACHES.
&&
.PREV DISCUSSION... /ISSUED 509 PM EDT TUE SEP 18 2012/
UPDATE...LINE OF SHOWERS AND THUNDERSTORMS OVER THE GULF OF
MEXICO IS MOVING TOWARDS THE GULF COAST/NAPLES AREA. THIS LINE
WILL IMPACT THIS AREA THROUGH EARLY EVENING. THE LINE IS MOVING
STEADILY EASTWARD...AND LATEST HRRR SHOWS THIS CONVECTION TRACKING
ACROSS SOUTH FLORIDA TONIGHT, REACHING THE EAST COAST METRO AREA
AT AROUND MIDNIGHT. GIVEN THE AMPLIFIED TROUGH AND INCOMING
SHORTWAVE, THIS SEEMS PLAUSIBLE. AS SUCH, HAVE UPDATED THE
FORECAST TO ACCOUNT FOR LIKELY ACTIVITY GULF COAST AND A CHANCE
OF THUNDERSTORMS EAST COAST METRO TONIGHT...AS THERE IS THE
POTENTIAL FOR THIS LINE OF STORMS TO MOVE INTO THE AREA TONIGHT.
IN OTHER WORDS, NOT OUR TYPICAL DIURNAL CYCLE. LIGHTNING/HEAVY
RAINS MAIN IMPACTS, BUT LOCALIZED WIND GUSTS OF 40-50 MPH
POSSIBLE. /GREGORIA
PREV DISCUSSION... /ISSUED 210 PM EDT TUE SEP 18 2012/
DISCUSSION...AN EXTREMELY COMPLEX WEATHER PATTERN IS DEVELOPING
ACROSS THE U.S. WHICH WILL HAVE ITS AFFECTS ON SOUTH FLORIDA. A MID
LEVEL TROUGH OVER THE GULF COAST NEAR THE LOWER MISSISSIPPI VALLEY
THIS MORNING IS BECOMING ABSORBED INTO LARGER SCALE TROUGH DEEPENING
INTO THE SOUTHEAST STATES WITH ITS ASSOCIATED COLD FRONT MOVING INTO
THE FL PANHANDLE. THIS SYSTEM WILL RAPIDLY LIFT TO THE NORTHEAST
TONIGHT AND WEDNESDAY AS ANOTHER TROUGH ROTATES THROUGH THE BASE OF
THE MAIN TROUGH AXIS AND MASSIVE RIDGES BUILD OVER THE WESTERN U.S.
AND THE WESTERN ATLANTIC. THIS IN TURN WILL ALLOW THE COLD FRONT TO
MOVE INTO NORTH CENTRAL FLORIDA AND STALL AS THE PENINSULA SOMEWHAT
BECOMES SANDWICHED IN BETWEEN ALL OF THESE SYSTEMS. THIS EVOLVING
SITUATION WILL ALSO RESULT IN ANOTHER DAY ON WEDNESDAY OF DEEP
SOUTHWESTERLY FLOW AND KEEP THE HIGHEST POPS OVER THE INTERIOR AND
EAST COAST METRO REGIONS.
ON THURSDAY, THE RIDGE OUT WEST WILL CONTINUE TO AMPLIFY WITH THE
MAIN ENERGY OF THE EASTERN TROUGH CONTINUING TO LIFT TO THE
NORTHEAST. THIS HAPPENS DUE TO THE ATLANTIC RIDGE SHIFTING WEST AS A
LARGE MID LEVEL TROUGH MOVES INTO THE CENTRAL ATLANTIC. REACTING TO
THIS WILL BE THE SFC RIDGE SHIFTING BACK NORTH PLACING SOUTH FLORIDA
IN A LOW LEVEL SOUTHEAST FLOW WITH WEAKER STEERING ALOFT. THE END
RESULT WILL BE SEA BREEZE DRIVEN ACTIVITY MOVING VERY LITTLE BUT
TENDING TO FAVOR THE INTERIOR SECTIONS. ALL IN ALL IN THE SHORT
TERM, MAJOR WEATHER SYSTEMS WILL BE FAR REMOVED FROM SOUTH FLORIDA
BUT PLACING US IN A FAVORABLE LOCATION FOR DAILY AFTERNOON/EVENING
SHOWERS AND THUNDERSTORMS.
IN THE EXTENDED PERIOD INTO THE WEEKEND AND EARLY NEXT WEEK, THE
WEATHER PATTERN WILL CHANGE VERY SLOWLY AND IT APPEARS THAT SOUTH
FLORIDA WILL BE UNDER THE INFLUENCE OF SEVERAL DAYS WITH SEA BREEZE
INTERACTION VARIETY THUNDERSTORM ACTIVITY. SO THE MAIN AREA OF
CONCERN FOR RAINFALL FROM THURSDAY INTO EARLY NEXT WEEK WILL BE THE
FAR WESTERN SUBURBS OF BOTH COASTS AND ANY LOCATION OVER THE
INTERIOR.
AVIATION...A RIDGE OF HIGH PRESSURE AT THE SURFACE AND ALOFT
SOUTHEAST OF THE AREA AND OVER THE FLA STRAITS WILL PERSIST THROUGH
THE PERIOD. WINDS WILL BE SOUTHERLY < 10 KTS THEN BECOME SSW TO SW
AND INCREASE 10 TO 15 KNOTS AS THE DAY PROGRESSES. NO E COAST SEA
BREEZE EXPECTED. WITH THE SSW-SW WIND FLOW...SOME VCSH AT KAPF WITH
VCTS EXPECTED AT ALL TERMINALS AFT 17Z. POSSIBLE THAT SOME MVFR
VSBY/CIG AT ANY ONE TERMINAL IF A TSRA MOVES OVER LATER TODAY.
MARINE...OUTSIDE OF SHOWERS AND THUNDERSTORMS, BOATING CONDITIONS
WILL BE TRANQUIL WITH A SOUTH TO SOUTHWEST WIND LESS THAN 15 KNOTS
THROUGH WEDNESDAY BECOMING SOUTHEASTERLY AT LESS THAN 15 KNOTS
THURSDAY INTO THE WEEKEND. THIS WILL RESULT IN SEAS OF LESS THAN 4 FEET.
FIRE WEATHER...NO PROBLEMS OR CONCERNS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 89 75 87 / 40 50 30 40
FORT LAUDERDALE 77 90 76 87 / 40 40 20 40
MIAMI 77 90 78 88 / 40 40 20 40
NAPLES 76 89 74 89 / 60 30 20 40
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...57/DG
AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1205 AM CDT MON SEP 17 2012
.UPDATE...
ISSUED 1205 AM CDT MON SEP 17 2012
REVISED AVIATION DISCUSSION FOR 06Z TAFS.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
ISSUED 308 PM CDT SUN SEP 16 2012
THE WEAK SYSTEM RESPONSIBLE FOR THE SHOWERS LAST NIGHT AND EARLY
THIS MORNING DISSIPATED AS IT MOVED EAST TODAY. IN ITS WAKE...SOME
PARTIAL CLEARING DEVELOPED ACROSS THE LOWER OHIO VALLEY. WITH THE
SOLAR HEATING...A FEW ISOLATED SHOWERS POPPED UP NEAR KPOF THIS
AFTERNOON.
OF MORE SIGNIFICANCE IS A LARGER AREA OF SHOWERS AND EVEN A FEW
THUNDERSTORMS ALONG AND SOUTH OF INTERSTATE 40 AS OF 19Z. THE
MAJORITY OF THE MODELS BRING THIS AREA NORTHWARD INTO SE MISSOURI
AND SW KENTUCKY TONIGHT...AND EVENTUALLY UP INTO THE EVV AREA
SOMETIME LATE TONIGHT OR MONDAY MORNING. THE PRIMARY EXCEPTION IS
THE SREF...WHICH TENDS TO SUPPRESS THE SOUTHERN STREAM SHORTWAVE
AND ITS ASSOCIATED QPF TO OUR SOUTH. THE 15Z RUC MODEL WAS RATHER
AGGRESSIVE BRINGING MOISTURE NORTH FROM ARKANSAS...AND THIS WILL
BE THE BASIS FOR THROWING OUT THE SREF.
THE RATHER STRONG 500 MB SHORTWAVE OVER TEXAS WILL MOVE EAST
NORTHEAST TONIGHT...BACKING OUR MID LEVEL WINDS INTO THE
SOUTHWEST. THIS WILL OPEN THE DOOR FOR A SERIES OF VORT CENTERS
THAT WILL MOVE NORTHEAST INTO THE OHIO VALLEY OVERNIGHT AND
MONDAY. DEEP LAYER SOUTHERLY FLOW WILL BRING A SURGE OF HIGHER PW
AIR NORTHWARD...WITH PW VALUES CLIMBING ABOVE 1.5 INCHES BY
MONDAY. POPS WILL RISE INTO THE LIKELY CATEGORY OVERNIGHT ACROSS
FAR SOUTHERN PORTIONS OF THE FA...WITH CHANCE POPS ELSEWHERE.
LIKELY POPS WILL SPREAD NORTH AND EAST MONDAY ACROSS MOST OF
WESTERN KY AND SW INDIANA.
A STRONG COLD FRONT WILL SWING SOUTHEAST ACROSS THE LOWER OHIO
VALLEY ON MONDAY NIGHT. AS THIS COLD FRONT ENCOUNTERS MOISTURE
ASSOCIATED WITH THE SOUTHERN STREAM SHORTWAVE...NUMEROUS SHOWERS
AND SOME ISOLATED THUNDER WILL PERSIST ACROSS MUCH OF OUR REGION.
WHILE STORM TOTAL QPF IS GENERALLY UNDER AN INCH...THERE COULD BE
SOME ISOLATED HEAVIER AMOUNTS. HEAVIEST TOTALS WILL BE IN KHOP
AREA. DUE TO WIDESPREAD CLOUDS AND WEAK WIND FIELDS...CONVECTIVE
DEVELOPMENT SHOULD BE LIMITED IN COVERAGE AND INTENSITY.
ONCE THE COLD FRONT PASSES MONDAY NIGHT...WINDS WILL INCREASE FROM
THE NORTHWEST. 850 MB WINDS WILL BE AVERAGING 25 TO 30 KNOTS TUESDAY.
SURFACE WIND GUSTS MAY REACH 30 MPH WITH STRONG MIXING ON TUESDAY.
STRONG DRYING BEHIND THE FRONT WILL RESULT IN RAPID CLEARING ON
TUESDAY MORNING...BUT 850 MB TEMPS WILL BE FALLING QUICKLY INTO
THE SINGLE DIGITS. THEREFORE...HIGHS WILL NOT GET OUT OF THE 60S
DESPITE A FAIRLY MILD START TO THE DAY IN THE 50S.
TUESDAY NIGHT WILL BE CHILLY AS A SURFACE RIDGE PASSES OVER THE
OHIO VALLEY. CLEAR SKIES AND NEARLY CALM WINDS WILL BE FAVORABLE
FOR STRONG RADIATIONAL COOLING. MOS GUIDANCE IS OFTEN TOO HIGH IN
SUCH CASES...AND FORECAST WILL BE WEIGHTED TOWARD THE COOLER 2M
NAM TEMPS. THIS YIELDS UPPER 30S IN MANY PLACES...WHICH SUGGESTS
THE POSSIBILITY OF SOME PATCHY FROST.
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
ISSUED 308 PM CDT SUN SEP 16 2012
TROUGHING ALOFT OVER THE WESTERN GREAT LAKES TO BEGIN THE PERIOD
IS EXPECTED TO AMPLIFY AND DEVELOP SOUTHWARD TOWARD THE LOWER OHIO
VALLEY/MID MISSISSIPPI VALLEY FRIDAY INTO SATURDAY. CONFIDENCE HAS
IMPROVED IN KEEPING THE FORECAST DRY WEDNESDAY THROUGH THURSDAY
NIGHT...AS NO RECENT MODELS HAVE ROTATED A SIGNIFICANT ENOUGH
DISTURBANCE THROUGH THE BASE OF THE TROUGH TO DRAG PRECIPITATION
INTO THE FOUR STATE REGION.
CONFIDENCE IS ALSO INCREASING IN TIMING OF THE PRIMARY COLD FRONT
THROUGH THE REGION FRIDAY AND FRIDAY NIGHT...AS THE 12Z GFS AND
ECMWF BOTH HAVE THIS GENERAL TIMING. POPS ARE STILL RATHER LOW THESE
PERIODS...AS THE MODELS NEED TO SHOW SOME STABILITY FIRST.
ALSO...SURFACE RIDGING IS EXPECTED TO PERSIST BETWEEN HERE AND THE
GULF COAST...SO THERE WILL BE LITTLE IN THE WAY OF RETURN FLOW OF
MOISTURE INTO THE FRONT. THAT SAID...THE MID AND UPPER LEVEL FORCING
MAY BE STRONG ENOUGH TO GENERATE SOME ELEVATED INSTABILITY...SO KEPT
THUNDER MENTION AREAWIDE FRIDAY AND FRIDAY NIGHT.
SLIGHT POPS ARE FORECAST FOR SATURDAY AND SATURDAY NIGHT TO ACCOUNT
FOR THE 00Z ECMWF TIMING OF THE FRONT. THE 00Z ECMWF ENSEMBLES DID
SHOW SOME SUPPORT FOR THE OLD OPERATIONAL RUN...SO CANNOT RULE IT
OUT JUST YET.
AS FOR TEMPERATURES...IT WILL FEEL RATHER COOLISH WITH HIGHS NEAR 70
AND PLENTY OF SUNSHINE WEDNESDAY. A NICE WARMING TREND IS EXPECTED
THURSDAY AND FRIDAY WITH A FEW 80S POSSIBLE ON FRIDAY. LOOKS LIKE
PLEASANT EARLY FALL CONDITIONS FOR NEXT WEEKEND...ESPECIALLY IF THE
OLD ECMWF IS NOT RIGHT. TEMPERATURES WILL BE A COUPLE OF CATEGORIES
BELOW NORMAL...BUT STILL IN THE 70S FOR HIGHS.
&&
.AVIATION...
ISSUED AT 1205 AM CDT MON SEP 17 2012
VFR CONDITIONS WILL GIVE WAY TO A NORTHWARD RETURN OF SHOWERS AND
LOCAL IFR CONDITIONS OVERNIGHT. IFR CEILINGS AND VISIBILITIES WILL
IMPACT PRIMARILY THE KCGI/KPAH SITES THROUGH DAYBREAK. THE SHOWER
ACTIVITY AND MVFR CEILINGS AND VISIBILITIES WILL SPREAD ACROSS THE
KEVV/KOWB SITES AFTER DAYBREAK MONDAY. THE SHOWERS WILL PERSIST INTO
MONDAY AFTERNOON...AND MAY BE ACCOMPANIED BY AN INCREASE IN
THUNDERSTORM COVERAGE. LIGHT WINDS OVERNIGHT WILL BECOME SOUTHERLY
ON MONDAY.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
MO...NONE.
IL...NONE.
IN...NONE.
&&
$$
SHORT TERM...MY
LONG TERM....DRS
AVIATION...RJP
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
425 PM EDT MON SEP 17 2012
.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 423 PM EDT MON SEP 17 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH AXIS
FROM HUDSON BAY INTO NW MN AND SE SOUTH DAKOTAS. A SHORTWAVE OVER NE
SD WAS MOVING INTO THE BASE OF THE TROUGH. AT THE SFC...A COLD FRONT
EXTENDED FROM NRN LOWER MI INTO SE WI. A LARGE POST-FRONTAL RAINBAND
FROM CNTRL WI INTO CNTRL UPPER MI WAS SUPPORTED BY MODERATE TO
STRONG MID LEVEL FGEN AND UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF
THE 250-300 MB JET. NRLY WINDS AND 850 MB TEMPS FALLING TO AROUND 3C
SUPPORTED HEAVIER LAKE ENHANCED RAIN SHOWERS INTO N CNTRL UPPER MI.
WITH DRIER AIR UPSTREAM OVER NE MN THE WRN CWA...OVER THE FAR WRN
CWA VCNTY IWD...HAS DIMINISHED OR ENDED.
TONIGHT...MDLS SUGGEST THAT THE STRONGER FGEN DYNAMICS WILL LIFT OFF
TO THE NE LATE THIS AFTERNOON AND EVENING. HOWEVER...WITH CAA
DROPPING 850 MB TEMPS TO NEAR -3C OVER LAKE SUPERIOR TONIGHT LEADING
TO LK-H8 DELTA/T TO AROUND 20C AND THE 700-500 MB TROUGH MOVING
IN...LAKE EFFECT RAIN SHOWERS WILL DEVELOP AND INTENSIFY OVERNIGHT
FOR LOCATIONS FAVORED BY N WINDS. WITH THE LOW FREEZING LEVEL...SOME
GRAUPEL WILL BE POSSIBLE WITH THE HEAVIER SHOWERS. LAKE INDUCED
TROUGHING WITH MORE OF AN NNE FLOW OVER THE ERN LAKE SHOULD MINIMIZE
PCPN INTO THE FAR ERN CWA. UPSLOPE FLOW WILL LEAD TO THE HIGHEST
PCPN AMOUNTS OVER THE HIGHER TERRAIN OVER MARQUETTE AND BARAGA
COUNTIES.
TUESDAY...LAKE EFFECT PCPN WILL CONTINUE WITH THE 850 MB THERMAL
TROF STILL OVER THE AREA. AS WINDS BACK AND BECOME MORE ANTICYCLONIC
AND SOME LOW LEVEL DRYING MOVES IN FROM THE WEST...THE PCPN SHOULD
DIMINISH SHOULD DIMINISH FROM WEST TO EAST. SHOWERS DOWNWIND OF LAKE
SUPERIOR BECOMING MORE SCATTERED THROUGH THE DAY FROM WEST TO EAST.
.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 423 PM EDT MON SEP 17 2012
TUE NGT...EXPECT LINGERING LK CLDS/-SHRA OVER MAINLY THE E HALF THRU
06Z TO END WITH APRCH OF PROGRESSIVE SHRTWV RDG/DNVA/ACCOMPANYING
DRY AIRMASS AND PASSAGE OF SFC HI PRES THAT CAUSES WSHFT TO THE SW
AND EXIT OF H85 THERMAL TROF. OTRW...LOOKS LIKE THERE SHOULD BE A
SEVERAL HOUR WINDOW OF OPTIMAL RADIATIONAL COOLING CONDITIONS ACROSS
MAINLY THE INTERIOR W AND CNTRL ACCOMPANYING THE PASSAGE OF THE RDG
AXIS/DRY AIR/LIGHT WINDS. OVER THE W...QUICKER WSHFT TO THE SW AFT
06Z WITH SHARPENING PRES GRADIENT AND SOME INCRSG HI/MID CLDS IN
ADVANCE OF NEXT SHRTWV DROPPING INTO MN WL END THE FAVORABLE COOLING
CONDITIONS WELL BEFORE SUNRISE...BUT NOT BEFORE TEMPS HAVE A CHANCE
TO CRASH BEFORE 06Z FM BLO NORMAL MAX READINGS ON TUE AFTN. OPTED TO
ISSUE FREEZE WATCH FOR THE INTERIOR W HALF...WHERE MOST GUIDANCE
SHOWS WDSPRD MIN TEMPS FALLING BLO 32.
WED...NEXT FAIRLY IMPRESSIVE SHRTWV DIVING SEWD THRU NW FLOW ALF
INTO MEAN TROF OVER ERN NAMERICA IS FCST TO MOVE NEAR UPR MI BY 00Z
THU. ALTHOUGH THE MSTR RETURN AHEAD OF THIS DISTURBANCE WL BE
ANEMIC DESPITE STRENGTHENING LLVL SLY FLOW...VIGOROUS DPVA/DEEP LYR
QVECTOR CNVGC SUPPORTS LIKELY POPS OVER THE N HALF OF THE CWA ON THE
CYC SIDE OF VORT MAX TRACK AND WHERE MOISTENING OFF LK SUP MIGHT
PLAY A ROLE.
WED NGT...DNVA/LARGER SCALE QVECTOR DVGC/HIER LVL DRYING IN THE WAKE
OF SHRTWV WL END LARGER SCALE PCPN CHCS W-E. BUT INCOMING AIRMASS WL
BE COLD ENUF WITH H85 TEMPS FCST AS LO AS 1-3C TO SUPPORT LK EFFECT
-SHRA IN AREAS IMPACTED BY FCST WNW FLOW...ESPECIALLY IF THE MORE
CYC FLOW SHOWN BY THE 12Z NAM/CNDN MODELS VERIFIES.
THU...THE ARRIVAL OF ANOTHER SHRTWV/SFC LO PRES TROF WL BRING MORE
SHRA CHCS DESPITE AN ABSENCE OF SGNFT DEEP LYR MOISTENING. QUESTIONS
ON TIMING/INTENSITY OF THIS DISTURBANCE INDICATE NO MORE THAN CHC
POPS ARE APPROPRIATE.
IN THE MEDIUM/EXTENDED RANGE...WITH MEAN TROF LINGERING OVER ERN
NAMERICA...EXPECT BLO NORMAL TEMPS TO PERSIST INTO EARLY NEXT WEEK.
MODELS SHOW A SERIES OF DISTURBANCES MOVING THRU THE MEAN TROF...SO
EXPECT SHOWERS TO PERSIST ESPECIALLY THRU SAT AND NEAR THE GREAT
LAKES. BEST CHC FOR A MORE WDSPRD RAINFALL APPEARS ON FRI WHEN
MODELS SHOW A PARTICULARLY STRONG DISTURBANCE IMPACTING THE AREA.
RECENT GFS RUNS SHOW THE MOST VIGOROUS SFC CYCLOGENESIS...AND WARM
LK WATERS MIGHT SUPPORT THAT SCENARIO. VARIOUS MODELS HINT THE UPR
TROF AXIS WL SHIFT A BIT FARTHER TO THE E NEXT SUN/MON WITH EPISODES
OF MORE ACYC FLOW/DRIER WX...BUT TIMING OF THESE FEATURES IS NOT
POSSIBLE ATTM. WL FOLLOW MODEL OF CONSENSUS LOWER POPS.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 132 PM EDT MON SEP 17 2012
A PERIOD OF STEADIER LIGHT RAIN OR DRIZZLE WILL AFFECT MAINLY CNTRL
UPPER MI THIS AFTERNOON. THE PCPN ALONG WITH UPSLOPE NRLY FLOW WILL
MAINTAIN LOWER END MVFR CIGS AT KSAW AND AT CMX. FARTHER WEST...SOME
DRIER AIR WILL MOVE INTO WRN UPPER MI THIS AFTERNOON WITH VFR
CONDITIONS AT IWD. ENOUGH COLD AIR WILL MOVE IN TONIGHT INTO TUE
MORNING FOR LAKE EFFECT PCPN WITH MAINLY MVFR CIGS FOR ALL OF THE TAF
SITES.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 423 PM EDT MON SEP 17 2012
20 TO 30 KT NORTH WINDS WILL CONTINUE IN THE SHORT TERM BUT DIMINISH
LATER TUESDAY AS HIGH PRESSURE BUILDS INTO THE REGION FROM THE WEST.
WINDS WILL GRADUALLY SHIFTING TO THE NW THEN W BY TUESDAY EVENING.
WINDS WILL BECOME LIGHT FOR AWHILE ON TUE NIGHT WITH THE PASSAGE OF
A HI PRES RIDGE ACROSS THE LAKE. BUT S WINDS WILL INCREASE QUICKLY
LATER AT NIGHT OVER THE W UNDER THE SHARPENING PRES GRADIENT BETWEEN
THE QUICKLY DEPARTING RIDGE AND AN INCOMING LO PRES TROUGH. AS THIS
DEEP TROF MOVES TO THE E...S WINDS ON WED MAY REACH GALE FORCE WHERE
THIS FLOW IS TYPICALLY ENHANCED OVER THE NCENTRAL AND E. ISSUED A
GALE WATCH WED AFTERNOON/EVENING IN THIS AREA TO ACCOUNT FOR THIS
STRONG FLOW AND FAIRLY UNSTABLE CONDITIONS OVER THE WARM LAKE WATER
THAT WILL ENHANCE MIXING. FOLLOWING THE PASSAGE OF THE TROF...LOOK
FOR A WIND SHIFT TO THE WNW WITH WINDS UP TO 25 TO 30 KTS INTO THU.
DEPENDING ON THE INTENSITY OF ANOTHER DISTURBANCE MOVING THRU THE
GREAT LAKES ON FRI/SAT...A STRONGER NNW FLOW IS POSSIBLE THEN. BUT
NO GALES ARE EXPECTED AT THIS TIME.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
FREEZE WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY MORNING
FOR MIZ002-004-005-009>013-084.
LAKE SUPERIOR...
GALE WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY EVENING
FOR LSZ267.
GALE WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY EVENING
FOR LSZ266.
GALE WATCH FROM WEDNESDAY AFTERNOON THROUGH WEDNESDAY EVENING
FOR LSZ264.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...JLB
MARINE...JLB/KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
138 AM EDT MON SEP 17 2012
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 356 PM EDT SUN SEP 16 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A W FLOW ALF OVER
THE GRT LKS BTWN DEEPENING TROF IN SCNTRL CAN AND PROGRESSIVE SHRTWV
RDG MOVING THRU THE GRT LKS. THERE IS A WEAK SHRTWV EMBEDDED IN THIS
FLOW MOVING THRU WRN LK SUP EARLY THIS AFTN...BUT DRY AIRMASS
DOMINATING THE AREA AND SHOWN ON THE 12Z RAOBS IS LIMITING ANY
ACCOMPANYING WX TO JUST SOME PATCHY MID/HI CLDS. A STEADY WSW LLVL
FLOW BTWN SFC HI PRES MOVING INTO THE MID ATLANTIC STATES AND A LO
PRES TROF OVER THE KEWEENAW/WRN LK SUP ASSOCIATED WITH THE SHRTWV IS
BEGINNING TO DRAW MORE SFC-H9 MSTR SHOWN ON THE 12Z MPX RAOB TOWARD
THE AREA...BUT SFC DEWPTS HAVE MIXED OUT TO AS LO AS THE MID 40S AS
OF EARLY THIS AFTN OVER THE CWA IN ADVANCE OF THIS LLVL MOISTENING.
FARTHER TO THE NW...A SHARP COLD FNT STRETCHES FM NW ONTARIO ACRS MN
INTO SDAKOTA. DUE TO THE DRYNESS OF AIRMASS AHEAD OF THIS FNT...
THERE IS CURRENTLY NO SHRA AHEAD OF THIS BNDRY. BUT MORE CLDS/SOME
-SHRA ARE EVIDENT OVER NDAKOTA IN THE COLD AIR TRAILING THE FNT WITH
APRCH OF SHRTWVS EMBEDDED IN THE DEEPENING TROF OVER SCNTRL CAN AND
ACCOMPANYING DPVA/H7-3 QVECTOR CNVGC AS WELL AS UPR DVGC IN RRQ OF
ASSOCIATED H3 JET MAX NEAR LK WINNIPEG.
LATE THIS AFTN/EARLY EVNG...ISSUED WILDFIRE POTENTIAL STATEMENT
EARLIER IN THE SHIFT TO ACCOUNT FOR COMBINATION OF WELL ABV NORMAL
TEMPS...MIN RH FALLING TO 30-35 PCT...GUSTY WSW WINDS ENHANCED BY
DEEP MIXING...AND RECENT DRYNESS. THE MOST CRITICAL CONDITIONS ARE
OVER THE SCNTRL...WHERE SHARPER PRES GRADIENT/HIER WINDS ARE
EVIDENT. QUESTION IS WHETHER RETURNING LLVL MSTR SHOWN ON THE 12Z
MPX RAOB MIGHT CAUSE SOME CONVECTION ON INCOMING LO PRES TROF UNDER
SOME DPVA/H85-5 QVECTOR CNVGC ASSOCIATED WITH APRCHG SHRTWV. RECENT
GFS RUNS HAVE BEEN QUITE CONSISTENT SHOWING SOME CONVECTION. SINCE
THE 12Z RAPID REFRESH RUC MODEL...THE FINER RES CNDN MODEL...AND THE
NAM HINT SOME CONVECTION WL IMPACT MAINLY THE CNTRL ZNS WHERE LLVL
MOISTENING AND DYNAMICS COME INTO PHASE NEAR PEAK HEATING TIME...
MAINTAINED SCHC POPS OVER THE CNTRL DESPITE MID LVL DRYNESS THAT WL
LIMIT COVERAGE OF ANY ASSOCIATED SHRA/TS TO ISOLD.
TNGT...ANY INSTABILITY SHRA/TS WL DISSIPATE WITH LOSS OF DAYTIME
HEATING/ARRIVAL OF SOME DNVA/H85-5 QVECTOR DVGC IN THE WAKE OF
INITIAL SHRTWV PASSAGE. THEN COLD FNT ASSOCIATED WITH DEEPENING TROF
IN CANADA IS PROGGED TO PUSH ACRS THE W HALF OF UPR MI BY 12Z MON.
SINCE THE SHARPEST H7-3 QVECTOR CNVGC ASSOCIATED WITH SHRTWVS MOVING
THRU THE AMPLIFYING UPR TROF/UPR DVGC IN RRQ OF H3 JET MAX MOVING
INTO NW ONTARIO IS FCST TO FOLLOW THE FROPA...EXPECT THE BULK OF ANY
PCPN TO FALL ON THE COLD SIDE OF THE BNDRY...AS IS OBSVD TODAY IN
THE NRN PLAINS. GOING POPS INCRSG TOWARD CATEGORICAL OVER THE W
APPEAR PRETTY MUCH ON TRACK...BUT DID CUT POPS OVER THE E HALF WITH
AN ABSENCE OF UPR FORCING IN THAT AREA WITHIN DRIER AIRMASS AHEAD OF
THE FROPA.
MON...AREA OF SHRA/CATEGORICAL POPS OVER THE W HALF IN THE MRNG
SHOULD SPREAD INTO THE E AS UPR TROF AXIS SHIFTS SLOWLY TO THE E AND
AREA OF IMPRESSIVE H7-3 QVECTOR CNVGC/UPR DVGC IN RRQ OF UPR JET TO
THE N SHIFTS TO THE E FOLLOWING SFC COLD FROPA. ALTHOUGH MODELS
INDICATE SOME MID LVL DRYING MIGHT IMPACT THE W IN THE AFTN...
ARRIVAL OF COLDER H85 AIR...WITH TEMPS AT THAT LVL FCST NEAR 0C OVER
THE W LATER IN THE DAY...IN CYC NLY FLOW TO W OF SFC LO THAT DVLPS
ON THE COLD FNT TO THE E SHOULD MAINTAIN LK ENHANCED SHOWERS IN THAT
AREA THRU 00Z TUE. ALTHOUGH TEMPS MIGHT WARM A BIT OVER THE E BEFORE
COLD FROPA/THICKER CLDS ARRIVE...READINGS ARE LIKELY TO FALL
FOLLOWING THE FROPA. SO NON-DIURNAL TEMP CURVE WITH STEADY/SLOWLY
FALLING TEMPS AT MOST PLACES IN THE AFTN APPEARS IN ORDER. DID
RETAIN A MENTION OF TS OVER THE E NEAR AND JUST BEHIND FROPA TIME AS
NAM FCST SDNGS HINT AT MUCAPE UP TO 500 J/KG. WITH A GUSTY N WIND...
SHRA... AND FALLING TEMPS THRU THE 50S...MON WL HAVE A DISTINCT
AUTUMNAL FEEL.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 356 PM EDT SUN SEP 16 2012
MAIN CONCERN IN THE MON NIGHT-WED TIME PERIOD CONTINUES TO BE
POPS...AND ALSO THE POSSIBILITY OF A HARD FREEZE TUESDAY NIGHT
ACROSS THE INTERIOR.
NO MAJOR CHANGES OF FORECAST THINKING FOR MONDAY NIGHT. THE UPPER
TROUGH GRADUALLY SETTLES ACROSS THE UPPER LAKES MONDAY
NIGHT...CENTERED OVER LAKE SUPERIOR BY TUESDAY MORNING. DESPITE THE
SURFACE LOW MOVING NE AND AWAY FROM THE REGION...A LAKE AGGREGATE
TROUGH WILL PERSIST ACROSS THE LAKE AS THE UPPER TROUGH MOVES
OVERHEAD. THIS WILL KEEP PBL WINDS PEGGED TO A NORTHERLY DIRECTION
ACROSS THE LAKE WHICH COMBINED WITH STEEPENING LOW LEVEL LAPSE RATES
AS THE 850MB TEMPS DROP TO -3C SHOULD FAVOR A FAIRLY PERSISTANT RAIN
ACROSS NORTH CENTRAL UPPER MICHIGAN MONDAY NIGHT. THERE ARE SOME
DIFFERENCES BETWEEN THE GFS AND NAM REGARDING THE EVOLUTION OF LOW
LEVEL WIND FLOW. THE GFS SUGGESTS THE WIND WILL BACK SLIGHTLY MONDAY
NIGHT OVER UPPER MI WHICH WOULD KEEP THE HEAVIEST PCPN JUST TO THE
EAST OF MARQUETTE. MEANWHILE...THE NAM WANTS TO KEEP THE WINDS A
LITTLE EAST OF NORTH...WHICH WOULD BE HIGHLY FAVORABLE FOR THE
HIGHER ELEVATIONS WEST OF MARQUETTE. WOULD NOT BE SURPRISED IF THE
GFS WIND VERIFIES...BUT IT MAY NOT MAKE A DIFFERENCE IN PCPN CHANCES
GIVEN THE LAKE ENHANCED NATURE OF THE PCPN VS. LAKE EFFECT. THE NAM
AND GFS ALSO SUGGEST THAT THE RAIN WILL DIMINISH MON NIGHT SOME OF
THE MID LEVEL MOISTURE BRIEFLY SCOURS OUT BEFORE A REINFORCING SHOT
OF MOISTURE MOVES IN BY TUE MORNING. ALTHOUGH THIS MAY HAPPEN...THE
FACT THAT THE LAKE INDUCED EQULIBRIUM LEVEL RISES TO OVER 20 KFT
OVERNIGHT MONDAY AND LARGE SCALE FORCING PERSISTS AS THE UPPER
TROUGH MOVES OVERHEAD SHOULD HELP TO OFFSET ANY MID LEVEL DRYING.
THE 4KM NAM NEST AND THE LOCAL WRF-ARW SUGGEST THE LAKE ENHANCED
PCPN WILL DEVELOP IN EARNEST AS SOON AS THE 850MB TEMPS DROP...SOON
AFTER 00Z. IN ADDITION...THE MORE LAKE ENHANCED NATURE OF THE PCPN
/VS LAKE EFFECT/ WOULD SUGGEST A MORE EVENLY DISTRUBUTED AREA OF
PCPN ACROSS ALL OF NORTH CENTRAL UPPER MI. WITH ALL OF THIS BEING
SAID...WILL KEEP CATEGORICAL POPS FOR MUCH OF NORTH CENTRAL UPPER
MICHIGAN CLOSER TO LAKE SUPERIOR...SIMILAR TO PREVIOUS FORECASTS. AS
FOR THE FAR EAST...PCPN MAY LIGHTEN UP MON NIGHT AS NORTHERLY PBL
FLOW NOT TERRRIBLY FAVORABLE FOR PCPN IN THAT AREA.
WITH THE UPPER TROUGH OVERHEAD ON TUESDAY...AND NEUTRAL TO SLIGHTLY
CYCLONIC PBL FLOW...WILL OPT TO MAINTAIN POPS AND RAISE THEM
SLIGHTLY TUESDAY NEAR LAKE SUPERIOR. AS THE TROUGH EXITS DURING THE
DAY...THE ASSOCIATED MID LVL FORCING WILL EXIT. THIS WILL ALLOW FOR
THE SURFACE RIDGING TO BUILD IN DURING THE DAY AND AS SUCH SHOULD
ALLOW FOR LAKE EFFECT PCPN TO GRADUALLY DIMINISH BY EVENING. AM NOT
IN TOO MUCH OF A HURRY TO END PCPN ON TUESDAY THOUGH...AS THE RIDGE
AXIS REALLY DOES NOT BUILD IN UNTIL AFTER 00Z WED. TEMPS WILL
STRUGGLE TO REACH 50 ACROSS THE INTERIOR DUE TO CLOUDS AND SHOWERS.
IN FACT...ALL NWP WANTS TO KEEP THE INTERIOR IN THE MID-UPPER 40S ON
TUESDAY. THIS SEEMS REASONABLE ESPECIALLY IF CLOUDS PERSIST...AND
HAVE THEREFORE LOWERED TEMPS ACROSS THE ENTIRE AREA ON
TUESDAY...WITH MOST INTERIOR SECTIONS STAYING IN THE 40S.
ANY REMAINING SHOWERS SHOULD END EARLY TUE EVENING...THEN THE RIDGE
BUILDS IN. THIS RIDGING COMBINED WITH PRECIPITABLE WATER VALUES AS
LOW AS 0.45 INCH SHOULD ALLOW FOR SKIES TO CLEAR OUT ACROSS THE
WEST. LAKE CLOUDS SHOULD HANG ON EAST...BUT EVEN THERE IT MAY CLEAR
OUT BY MORNING. REGARDLESS...WITH CLEAR SKIES AND LIGHT WINDS...IT
SHOULD GET COLD ACROSS THE INTERIOR. AM NOW THINKING A HARD FREEZE
IS IN STORE BY WED MORNING FOR THE INTERIOR WEST. EVEN THE RAW NAM
WHICH USUALLY HAS A WARM BIAS DURING RADIATIONAL COOLING HAS TEMPS
ACROSS IRON COUNTY IN THE 20S...AND THE GFS HAS 2M TEMPS IN THE
LOWER 30S. NAM MOS GUIDANCE SUGGEST SIMILAR TO COLDER TEMPS FOR TUE
NIGHT. WILL THEREFORE LOWER TEMPS ACROSS THE ENTIRE AREA TUE NIGHT.
SOME MODEL DIFFERENCES REGARDING THE NEXT SYSTEM. THE GFS IS MUCH
FASTER...UP TO 12 HRS...BRINIGING PCPN IN BY LUNCHTIME WED.
MEANWHILE...THE NAM AND GEM ARE MUCH SLOWER...NOT BRINGING IN PCPN
UNTIL WED EVENING. THE COMBINATION OF THE INCREASING WARM
ADVECTION/ISENTROPIC LIFT AND INCREASING MID LVL MOISTURE ACROSS THE
WEST WED AFTN IN THE NAM WOULD IMPLY AT LEAST A CHANCE FOR RAIN WED
AFTN DESPITE THE MODEL NOT PRINTING OUT MUCH QPF. WILL THEREFORE GO
WITH 30 PCPN CHANCE FOR SHOWERS WED AFTN FOR WESTERN UPPER MI. WILL
KEEP A DRY FCST FOR THE REMAINDER OF THE AREA.
IN THE EXTENDED /WED NIGHT-NEXT SUNDAY/...THE FULL AMPLITUDE LONG
WAVE TROUGH WILL PERSIST FROM HUDSON BAY THROUGH THE GREAT LAKES
REGION THROUGH THE PERIOD. THIS WILL KEEP THE WEATHER FAIRLY
UNSETTLED THROUGH SATURDAY. THE NUMERICAL GUIDANCE IS IN GOOD
AGREEMENT REGARDING THE LONG WAVE...BUT DIFFER SOMEWHAT ON SPECIFIC
DETAILS REGARDING INDIVIDUAL SHORT WAVES AND AS SUCH THEY DIFFER ON
EXACT POSITION OF THE LONG WAVE TROUGH. THE MAIN OUTLIER WITH THE
00Z RUN IS THE OPERATIONAL ECMWF WHICH KEEPS THE MAIN TROUGH
POSITIVLY TILTED WITH THE TROUGH AXIS FURTHER WEST. THIS IS LIKELY
DUE TO THAT MODEL ALLOWING STRONGER SHORT WAVE ENERGY TO DIVE DOWN
THE BACK SIDE OF THE UPPER TROUGH THURSDAY INTO FRIDAY. AT THIS
TIME...THIS IS NOT SUPPORTED BY THE GFS...NOR THE MAJORITY OF THE
ENSEMBLE MEMBERS FROM THE GFS AND ECMWF. WILL THEREFORE TREND THE
FORECAST TOWARD THE GFS/GEM COMPROMISE...BUT THE REALITY OF THE
MATTER IS THAT EITHER SOLUTION WOULD MAINTAIN UNSETTLED WEATHER FOR
THE AREA FOR MUCH OF THE EXTENDED. THERE WILL BE PERIODS OF DRY
WEATHER...BUT GIVEN THE UNCERTAINTY OF EXACT SHORT WAVE POSITIONS
ESPECIALLY FOR LATE INTO THE WEEK...IT WILL BE TOUGH TO PIN DOWN
SPECIFICS. WITH THAT BEING SAID...WILL NEED TO GO WITH CHANCE POPS
EACH DAY OF THE EXTENDED THROUGH SATURDAY. THE BEST CHANCE FOR RAIN
MAY BE FRIDAY INTO FRIDAY NIGHT WHERE THE GFS AND GEM BOTH AGREE ON
A WAVE MOVING ACROSS THE UPPER LAKES WITH LOW PRESSURE ACROSS THE
AREA. IN FACT...EVEN THE ECMWF SHOWS PCPN FRIDAY. BY SUNDAY...THE
GFS SUGGESTS THAT THE TROUGH WILL SLOWLY EXIT EAST OF THE
AREA...ALLOWING SOME DRYING TO MOVE IN. WILL THEREFORE GO WITH A DRY
FORECAST FOR NOW ON SUNDAY...BUT THAT IS SUBJECT TO CHANGE IF THE
TROUGH IS A LITTLE SLOWER.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 138 AM EDT MON SEP 17 2012
AFTER PASSAGE OF COLD FRONT...ABUNDANT MOISTURE WILL PULL WIDESPREAD
RAIN AND CLOUDS EASTWARD ACROSS THE TAF SITES OVERNIGHT. EXPECT SOME
LOWERING OF VIS/CIGS AS A RESULT...THOUGH LATEST MODEL GUIDANCE SHOWS
A LOW LEVEL DRY AIR POCKET WHICH COULD INHIBIT SOME OF THE IFR
VIS/CIGS EXPECTED IN LAST TAF ISSUANCE. CHOSE TO KEEP SITES
MVFR...THOUGH SOME AMENDMENTS FOR EXACT TIMINGS AND CIG/VIS MAY NEED
TO BE MADE. THE EXCEPTION IS KSAW...WHICH DUE TO MOIST COLD AIRMASS
PULLING STRONG WINDS OFF THE WARM LAKE...COULD SEE HEAVIEST RAIN
SHOWERS...SO SOME IFR CONDITIONS ARE POSSIBLE. MAIN FORCING WILL
MOVE OFF TO THE EAST DURING THE AFTERNOON BRINGING RAIN TO AN END AT
KCMX. HOWEVER...COLD AIRMASS OVER WARM LAKE AND RESULTING STRONG N
WINDS WILL MAKE CONDITIONS FAVORABLE FOR LAKE EFFECT RAIN SHOWERS
/TRANSITION FROM RA TO SHRA IN TAF/ FOR KIWD AND KSAW THROUGH
REMAINDER OF TAF PERIOD.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 356 PM EDT SUN SEP 16 2012
EXPECT RELATIVELY LIGHT WINDS UNDER 20 KTS FOR MOST OF THIS EVENING
OVER THE LAKE WITH FAIRLY HI STABILITY/A WEAK LO PRES TROF CROSSING
THE AREA. THEN EXPECT A WIND SHIFT TO THE NNW WITH THE PASSAGE OF A
STRONG COLD FRONT BY LATE EVENING OVER THE W AND THEN ON MON MORNING
OVER THE E HALF. AS COLDER AIR FOLLOWS THE FRONT OVER THE RELATIVELY
WARM WATERS OF LAKE SUPERIOR AND STABILITY DECREASES...EXPECT
STRONGER N WINDS TO 25 TO 30 KTS TO DEVELOP W TO E. BUT SINCE LATEST
GUIDANCE INDICATES THE PRES GRADIENT WILL BE WEAKER THAN EXPECTED ON
PREVIOUS SHIFTS...GALES NOW APPEAR UNLIKELY. SO THE GOING GALE WATCH
THAT WAS IN EFFECT ON MON OVER PORTIONS OF THE W HALF WAS DROPPED.
NORTH WINDS WILL PERSIST MONDAY NIGHT INTO TUESDAY BEFORE GRADUALLY
SHIFTING TO THE NW THEN W BY TUESDAY EVENING. ANOTHER LOW PRESSURE
TROUGH WILL APPROACH WED THEN PASS ACROSS THE LAKE WED NIGHT. AHEAD
OF THE TROUGH...WINDS WILL TURN SOUTHERLY AT 15-25 KT...THEN WILL
TURN W-NW BY THU MORNING. OTHER THAN SOME GUSTS CLOSE TO GALE FORCE
MONDAY EVENING...GALES ARE NOT EXPECTED AT THIS TIME THROUGH FRIDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...MRD
AVIATION...JMW
MARINE...KC/MRD
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
116 AM EDT MON SEP 17 2012
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 356 PM EDT SUN SEP 16 2012
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A W FLOW ALF OVER
THE GRT LKS BTWN DEEPENING TROF IN SCNTRL CAN AND PROGRESSIVE SHRTWV
RDG MOVING THRU THE GRT LKS. THERE IS A WEAK SHRTWV EMBEDDED IN THIS
FLOW MOVING THRU WRN LK SUP EARLY THIS AFTN...BUT DRY AIRMASS
DOMINATING THE AREA AND SHOWN ON THE 12Z RAOBS IS LIMITING ANY
ACCOMPANYING WX TO JUST SOME PATCHY MID/HI CLDS. A STEADY WSW LLVL
FLOW BTWN SFC HI PRES MOVING INTO THE MID ATLANTIC STATES AND A LO
PRES TROF OVER THE KEWEENAW/WRN LK SUP ASSOCIATED WITH THE SHRTWV IS
BEGINNING TO DRAW MORE SFC-H9 MSTR SHOWN ON THE 12Z MPX RAOB TOWARD
THE AREA...BUT SFC DEWPTS HAVE MIXED OUT TO AS LO AS THE MID 40S AS
OF EARLY THIS AFTN OVER THE CWA IN ADVANCE OF THIS LLVL MOISTENING.
FARTHER TO THE NW...A SHARP COLD FNT STRETCHES FM NW ONTARIO ACRS MN
INTO SDAKOTA. DUE TO THE DRYNESS OF AIRMASS AHEAD OF THIS FNT...
THERE IS CURRENTLY NO SHRA AHEAD OF THIS BNDRY. BUT MORE CLDS/SOME
-SHRA ARE EVIDENT OVER NDAKOTA IN THE COLD AIR TRAILING THE FNT WITH
APRCH OF SHRTWVS EMBEDDED IN THE DEEPENING TROF OVER SCNTRL CAN AND
ACCOMPANYING DPVA/H7-3 QVECTOR CNVGC AS WELL AS UPR DVGC IN RRQ OF
ASSOCIATED H3 JET MAX NEAR LK WINNIPEG.
LATE THIS AFTN/EARLY EVNG...ISSUED WILDFIRE POTENTIAL STATEMENT
EARLIER IN THE SHIFT TO ACCOUNT FOR COMBINATION OF WELL ABV NORMAL
TEMPS...MIN RH FALLING TO 30-35 PCT...GUSTY WSW WINDS ENHANCED BY
DEEP MIXING...AND RECENT DRYNESS. THE MOST CRITICAL CONDITIONS ARE
OVER THE SCNTRL...WHERE SHARPER PRES GRADIENT/HIER WINDS ARE
EVIDENT. QUESTION IS WHETHER RETURNING LLVL MSTR SHOWN ON THE 12Z
MPX RAOB MIGHT CAUSE SOME CONVECTION ON INCOMING LO PRES TROF UNDER
SOME DPVA/H85-5 QVECTOR CNVGC ASSOCIATED WITH APRCHG SHRTWV. RECENT
GFS RUNS HAVE BEEN QUITE CONSISTENT SHOWING SOME CONVECTION. SINCE
THE 12Z RAPID REFRESH RUC MODEL...THE FINER RES CNDN MODEL...AND THE
NAM HINT SOME CONVECTION WL IMPACT MAINLY THE CNTRL ZNS WHERE LLVL
MOISTENING AND DYNAMICS COME INTO PHASE NEAR PEAK HEATING TIME...
MAINTAINED SCHC POPS OVER THE CNTRL DESPITE MID LVL DRYNESS THAT WL
LIMIT COVERAGE OF ANY ASSOCIATED SHRA/TS TO ISOLD.
TNGT...ANY INSTABILITY SHRA/TS WL DISSIPATE WITH LOSS OF DAYTIME
HEATING/ARRIVAL OF SOME DNVA/H85-5 QVECTOR DVGC IN THE WAKE OF
INITIAL SHRTWV PASSAGE. THEN COLD FNT ASSOCIATED WITH DEEPENING TROF
IN CANADA IS PROGGED TO PUSH ACRS THE W HALF OF UPR MI BY 12Z MON.
SINCE THE SHARPEST H7-3 QVECTOR CNVGC ASSOCIATED WITH SHRTWVS MOVING
THRU THE AMPLIFYING UPR TROF/UPR DVGC IN RRQ OF H3 JET MAX MOVING
INTO NW ONTARIO IS FCST TO FOLLOW THE FROPA...EXPECT THE BULK OF ANY
PCPN TO FALL ON THE COLD SIDE OF THE BNDRY...AS IS OBSVD TODAY IN
THE NRN PLAINS. GOING POPS INCRSG TOWARD CATEGORICAL OVER THE W
APPEAR PRETTY MUCH ON TRACK...BUT DID CUT POPS OVER THE E HALF WITH
AN ABSENCE OF UPR FORCING IN THAT AREA WITHIN DRIER AIRMASS AHEAD OF
THE FROPA.
MON...AREA OF SHRA/CATEGORICAL POPS OVER THE W HALF IN THE MRNG
SHOULD SPREAD INTO THE E AS UPR TROF AXIS SHIFTS SLOWLY TO THE E AND
AREA OF IMPRESSIVE H7-3 QVECTOR CNVGC/UPR DVGC IN RRQ OF UPR JET TO
THE N SHIFTS TO THE E FOLLOWING SFC COLD FROPA. ALTHOUGH MODELS
INDICATE SOME MID LVL DRYING MIGHT IMPACT THE W IN THE AFTN...
ARRIVAL OF COLDER H85 AIR...WITH TEMPS AT THAT LVL FCST NEAR 0C OVER
THE W LATER IN THE DAY...IN CYC NLY FLOW TO W OF SFC LO THAT DVLPS
ON THE COLD FNT TO THE E SHOULD MAINTAIN LK ENHANCED SHOWERS IN THAT
AREA THRU 00Z TUE. ALTHOUGH TEMPS MIGHT WARM A BIT OVER THE E BEFORE
COLD FROPA/THICKER CLDS ARRIVE...READINGS ARE LIKELY TO FALL
FOLLOWING THE FROPA. SO NON-DIURNAL TEMP CURVE WITH STEADY/SLOWLY
FALLING TEMPS AT MOST PLACES IN THE AFTN APPEARS IN ORDER. DID
RETAIN A MENTION OF TS OVER THE E NEAR AND JUST BEHIND FROPA TIME AS
NAM FCST SDNGS HINT AT MUCAPE UP TO 500 J/KG. WITH A GUSTY N WIND...
SHRA... AND FALLING TEMPS THRU THE 50S...MON WL HAVE A DISTINCT
AUTUMNAL FEEL.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 356 PM EDT SUN SEP 16 2012
MAIN CONCERN IN THE MON NIGHT-WED TIME PERIOD CONTINUES TO BE
POPS...AND ALSO THE POSSIBILITY OF A HARD FREEZE TUESDAY NIGHT
ACROSS THE INTERIOR.
NO MAJOR CHANGES OF FORECAST THINKING FOR MONDAY NIGHT. THE UPPER
TROUGH GRADUALLY SETTLES ACROSS THE UPPER LAKES MONDAY
NIGHT...CENTERED OVER LAKE SUPERIOR BY TUESDAY MORNING. DESPITE THE
SURFACE LOW MOVING NE AND AWAY FROM THE REGION...A LAKE AGGREGATE
TROUGH WILL PERSIST ACROSS THE LAKE AS THE UPPER TROUGH MOVES
OVERHEAD. THIS WILL KEEP PBL WINDS PEGGED TO A NORTHERLY DIRECTION
ACROSS THE LAKE WHICH COMBINED WITH STEEPENING LOW LEVEL LAPSE RATES
AS THE 850MB TEMPS DROP TO -3C SHOULD FAVOR A FAIRLY PERSISTANT RAIN
ACROSS NORTH CENTRAL UPPER MICHIGAN MONDAY NIGHT. THERE ARE SOME
DIFFERENCES BETWEEN THE GFS AND NAM REGARDING THE EVOLUTION OF LOW
LEVEL WIND FLOW. THE GFS SUGGESTS THE WIND WILL BACK SLIGHTLY MONDAY
NIGHT OVER UPPER MI WHICH WOULD KEEP THE HEAVIEST PCPN JUST TO THE
EAST OF MARQUETTE. MEANWHILE...THE NAM WANTS TO KEEP THE WINDS A
LITTLE EAST OF NORTH...WHICH WOULD BE HIGHLY FAVORABLE FOR THE
HIGHER ELEVATIONS WEST OF MARQUETTE. WOULD NOT BE SURPRISED IF THE
GFS WIND VERIFIES...BUT IT MAY NOT MAKE A DIFFERENCE IN PCPN CHANCES
GIVEN THE LAKE ENHANCED NATURE OF THE PCPN VS. LAKE EFFECT. THE NAM
AND GFS ALSO SUGGEST THAT THE RAIN WILL DIMINISH MON NIGHT SOME OF
THE MID LEVEL MOISTURE BRIEFLY SCOURS OUT BEFORE A REINFORCING SHOT
OF MOISTURE MOVES IN BY TUE MORNING. ALTHOUGH THIS MAY HAPPEN...THE
FACT THAT THE LAKE INDUCED EQULIBRIUM LEVEL RISES TO OVER 20 KFT
OVERNIGHT MONDAY AND LARGE SCALE FORCING PERSISTS AS THE UPPER
TROUGH MOVES OVERHEAD SHOULD HELP TO OFFSET ANY MID LEVEL DRYING.
THE 4KM NAM NEST AND THE LOCAL WRF-ARW SUGGEST THE LAKE ENHANCED
PCPN WILL DEVELOP IN EARNEST AS SOON AS THE 850MB TEMPS DROP...SOON
AFTER 00Z. IN ADDITION...THE MORE LAKE ENHANCED NATURE OF THE PCPN
/VS LAKE EFFECT/ WOULD SUGGEST A MORE EVENLY DISTRUBUTED AREA OF
PCPN ACROSS ALL OF NORTH CENTRAL UPPER MI. WITH ALL OF THIS BEING
SAID...WILL KEEP CATEGORICAL POPS FOR MUCH OF NORTH CENTRAL UPPER
MICHIGAN CLOSER TO LAKE SUPERIOR...SIMILAR TO PREVIOUS FORECASTS. AS
FOR THE FAR EAST...PCPN MAY LIGHTEN UP MON NIGHT AS NORTHERLY PBL
FLOW NOT TERRRIBLY FAVORABLE FOR PCPN IN THAT AREA.
WITH THE UPPER TROUGH OVERHEAD ON TUESDAY...AND NEUTRAL TO SLIGHTLY
CYCLONIC PBL FLOW...WILL OPT TO MAINTAIN POPS AND RAISE THEM
SLIGHTLY TUESDAY NEAR LAKE SUPERIOR. AS THE TROUGH EXITS DURING THE
DAY...THE ASSOCIATED MID LVL FORCING WILL EXIT. THIS WILL ALLOW FOR
THE SURFACE RIDGING TO BUILD IN DURING THE DAY AND AS SUCH SHOULD
ALLOW FOR LAKE EFFECT PCPN TO GRADUALLY DIMINISH BY EVENING. AM NOT
IN TOO MUCH OF A HURRY TO END PCPN ON TUESDAY THOUGH...AS THE RIDGE
AXIS REALLY DOES NOT BUILD IN UNTIL AFTER 00Z WED. TEMPS WILL
STRUGGLE TO REACH 50 ACROSS THE INTERIOR DUE TO CLOUDS AND SHOWERS.
IN FACT...ALL NWP WANTS TO KEEP THE INTERIOR IN THE MID-UPPER 40S ON
TUESDAY. THIS SEEMS REASONABLE ESPECIALLY IF CLOUDS PERSIST...AND
HAVE THEREFORE LOWERED TEMPS ACROSS THE ENTIRE AREA ON
TUESDAY...WITH MOST INTERIOR SECTIONS STAYING IN THE 40S.
ANY REMAINING SHOWERS SHOULD END EARLY TUE EVENING...THEN THE RIDGE
BUILDS IN. THIS RIDGING COMBINED WITH PRECIPITABLE WATER VALUES AS
LOW AS 0.45 INCH SHOULD ALLOW FOR SKIES TO CLEAR OUT ACROSS THE
WEST. LAKE CLOUDS SHOULD HANG ON EAST...BUT EVEN THERE IT MAY CLEAR
OUT BY MORNING. REGARDLESS...WITH CLEAR SKIES AND LIGHT WINDS...IT
SHOULD GET COLD ACROSS THE INTERIOR. AM NOW THINKING A HARD FREEZE
IS IN STORE BY WED MORNING FOR THE INTERIOR WEST. EVEN THE RAW NAM
WHICH USUALLY HAS A WARM BIAS DURING RADIATIONAL COOLING HAS TEMPS
ACROSS IRON COUNTY IN THE 20S...AND THE GFS HAS 2M TEMPS IN THE
LOWER 30S. NAM MOS GUIDANCE SUGGEST SIMILAR TO COLDER TEMPS FOR TUE
NIGHT. WILL THEREFORE LOWER TEMPS ACROSS THE ENTIRE AREA TUE NIGHT.
SOME MODEL DIFFERENCES REGARDING THE NEXT SYSTEM. THE GFS IS MUCH
FASTER...UP TO 12 HRS...BRINIGING PCPN IN BY LUNCHTIME WED.
MEANWHILE...THE NAM AND GEM ARE MUCH SLOWER...NOT BRINGING IN PCPN
UNTIL WED EVENING. THE COMBINATION OF THE INCREASING WARM
ADVECTION/ISENTROPIC LIFT AND INCREASING MID LVL MOISTURE ACROSS THE
WEST WED AFTN IN THE NAM WOULD IMPLY AT LEAST A CHANCE FOR RAIN WED
AFTN DESPITE THE MODEL NOT PRINTING OUT MUCH QPF. WILL THEREFORE GO
WITH 30 PCPN CHANCE FOR SHOWERS WED AFTN FOR WESTERN UPPER MI. WILL
KEEP A DRY FCST FOR THE REMAINDER OF THE AREA.
IN THE EXTENDED /WED NIGHT-NEXT SUNDAY/...THE FULL AMPLITUDE LONG
WAVE TROUGH WILL PERSIST FROM HUDSON BAY THROUGH THE GREAT LAKES
REGION THROUGH THE PERIOD. THIS WILL KEEP THE WEATHER FAIRLY
UNSETTLED THROUGH SATURDAY. THE NUMERICAL GUIDANCE IS IN GOOD
AGREEMENT REGARDING THE LONG WAVE...BUT DIFFER SOMEWHAT ON SPECIFIC
DETAILS REGARDING INDIVIDUAL SHORT WAVES AND AS SUCH THEY DIFFER ON
EXACT POSITION OF THE LONG WAVE TROUGH. THE MAIN OUTLIER WITH THE
00Z RUN IS THE OPERATIONAL ECMWF WHICH KEEPS THE MAIN TROUGH
POSITIVLY TILTED WITH THE TROUGH AXIS FURTHER WEST. THIS IS LIKELY
DUE TO THAT MODEL ALLOWING STRONGER SHORT WAVE ENERGY TO DIVE DOWN
THE BACK SIDE OF THE UPPER TROUGH THURSDAY INTO FRIDAY. AT THIS
TIME...THIS IS NOT SUPPORTED BY THE GFS...NOR THE MAJORITY OF THE
ENSEMBLE MEMBERS FROM THE GFS AND ECMWF. WILL THEREFORE TREND THE
FORECAST TOWARD THE GFS/GEM COMPROMISE...BUT THE REALITY OF THE
MATTER IS THAT EITHER SOLUTION WOULD MAINTAIN UNSETTLED WEATHER FOR
THE AREA FOR MUCH OF THE EXTENDED. THERE WILL BE PERIODS OF DRY
WEATHER...BUT GIVEN THE UNCERTAINTY OF EXACT SHORT WAVE POSITIONS
ESPECIALLY FOR LATE INTO THE WEEK...IT WILL BE TOUGH TO PIN DOWN
SPECIFICS. WITH THAT BEING SAID...WILL NEED TO GO WITH CHANCE POPS
EACH DAY OF THE EXTENDED THROUGH SATURDAY. THE BEST CHANCE FOR RAIN
MAY BE FRIDAY INTO FRIDAY NIGHT WHERE THE GFS AND GEM BOTH AGREE ON
A WAVE MOVING ACROSS THE UPPER LAKES WITH LOW PRESSURE ACROSS THE
AREA. IN FACT...EVEN THE ECMWF SHOWS PCPN FRIDAY. BY SUNDAY...THE
GFS SUGGESTS THAT THE TROUGH WILL SLOWLY EXIT EAST OF THE
AREA...ALLOWING SOME DRYING TO MOVE IN. WILL THEREFORE GO WITH A DRY
FORECAST FOR NOW ON SUNDAY...BUT THAT IS SUBJECT TO CHANGE IF THE
TROUGH IS A LITTLE SLOWER.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 109 AM EDT MON SEP 17 2012
AFTER PASSAGE OF COLD FRONT...ABUNDANT MOISTURE WILL PULL WIDESPREAD
RAIN AND CLOUDS EASTWARD ACROSS THE TAF SITES OVERNIGHT. EXPECT SOME
LOWERING OF VIS/CIGS AS A RESULT...THOUGH LATEST MODEL GUIDANCE SHOWS
A LOW LEVEL DRY AIR POCKET WHICH COULD INHIBIT SOME OF THE IFR
VIS/CIGS EXPECTED IN LAST TAF ISSUANCE. CHOSE TO KEEP SITES
MVFR...THOUGH SOME AMENDMENTS FOR EXACT TIMINGS AND CIG/VIS MAY NEED
TO BE MADE. THE EXCEPTION IS KSAW...WHICH DUE TO MOIST COLD AIRMASS
PULLING STRONG WINDS OFF THE WARM LAKE...COULD SEE HEAVIEST RAIN
SHOWERS...SO SOME IFR CONDITIONS ARE POSSIBLE. MAIN FORCING WILL
MOVE OFF TO THE EAST DURING THE AFTERNOON BRINGING RAIN TO AN END AT
KCMX. HOWEVER...COLD AIRMASS OVER WARM LAKE AND RESULTING STRONG N
WINDS WILL MAKE CONDITIONS FAVORABLE FOR LAKE EFFECT RAIN SHOWERS
/TRANSITION FROM RA TO SHRA IN TAF/ FOR KIWD AND KSAW THROUGH
REMAINDER OF TAF PERIOD. &&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 356 PM EDT SUN SEP 16 2012
EXPECT RELATIVELY LIGHT WINDS UNDER 20 KTS FOR MOST OF THIS EVENING
OVER THE LAKE WITH FAIRLY HI STABILITY/A WEAK LO PRES TROF CROSSING
THE AREA. THEN EXPECT A WIND SHIFT TO THE NNW WITH THE PASSAGE OF A
STRONG COLD FRONT BY LATE EVENING OVER THE W AND THEN ON MON MORNING
OVER THE E HALF. AS COLDER AIR FOLLOWS THE FRONT OVER THE RELATIVELY
WARM WATERS OF LAKE SUPERIOR AND STABILITY DECREASES...EXPECT
STRONGER N WINDS TO 25 TO 30 KTS TO DEVELOP W TO E. BUT SINCE LATEST
GUIDANCE INDICATES THE PRES GRADIENT WILL BE WEAKER THAN EXPECTED ON
PREVIOUS SHIFTS...GALES NOW APPEAR UNLIKELY. SO THE GOING GALE WATCH
THAT WAS IN EFFECT ON MON OVER PORTIONS OF THE W HALF WAS DROPPED.
NORTH WINDS WILL PERSIST MONDAY NIGHT INTO TUESDAY BEFORE GRADUALLY
SHIFTING TO THE NW THEN W BY TUESDAY EVENING. ANOTHER LOW PRESSURE
TROUGH WILL APPROACH WED THEN PASS ACROSS THE LAKE WED NIGHT. AHEAD
OF THE TROUGH...WINDS WILL TURN SOUTHERLY AT 15-25 KT...THEN WILL
TURN W-NW BY THU MORNING. OTHER THAN SOME GUSTS CLOSE TO GALE FORCE
MONDAY EVENING...GALES ARE NOT EXPECTED AT THIS TIME THROUGH FRIDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...MRD
AVIATION...JMW
MARINE...KC/MRD
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
118 PM CDT MON SEP 17 2012
.SHORT TERM...
ISSUED AT 334 AM CDT MON SEP 17 2012
(TODAY AND TONIGHT)
WHEN I WALKED IN THE DOOR AT 1000 PM LAST NIGHT I THOUGHT THE
FORECAST WAS GOING TO BE A BIT MORE CLEAR CUT THAN IT IS NOW. AREAS
OF DENSE FOG HAVE DEVELOPED OVERNIGHT...ESPECIALLY FROM ST LOUIS
NORTHWARD WHERE THERE ARE ONLY THIN HIGH CLOUDS AT THIS TIME.
MEANWHILE A PESKY AREA OF SHOWERS HAS ALSO DEVELOPED FROM SRN IL
ACROSS THE EASTERN OZARKS...APPARENTLY IN RESPONSE TO WEAK LOW
LEVEL WAA. VISIBILITIES HAVE IMPROVED SLIGHTLY IN THE ST LOUIS
AREA WITHIN THE LAST HOUR...AND THIS MAY BE DUE TO SOME THICKER
CLOUD COVER. I WILL HAVE TO MENTION SOME DENSE FOG THIS
MORNING...PROBABLY FROM I-70 NORTHWARD...BUT DONT HAVE ANY PLANS
FOR AN ADVISORY. THE PRECIPITATION TRENDS ARE A LITTLE MORE MURKY.
THE MODEL QPFS AND HRRR WANT TO KEEP A PERSIST THREAT OF SHOWERS
ACROSS THE SRN CWA THRU THE MORNING AND RAMPING UP INTO THE
AFTERNOON IN RESPONSE TO CONTINUED WAA AND LITTLE VORTS RIDING
ALONG THE NORTHERN FRINGE OF THE SHEAR AXIS THROUGH THE BOOTHEEL
REGION. MEANWHILE IT STILL LOOKS AS THOUGH THE AIR MASS ALONG AND
AHEAD OF THE ENCROACHING COLD FRONT WILL DESTABILIZE THIS
AFTERNOON AND THERE WILL BE SUFFICIENT FORCING FOR THE DEVELOPMENT
OF SCATTERED SHOWERS AND THUNDERSTORMS AND POSSIBLY A BROKEN LINE
FROM EASTERN MO INTO IL. THE POTENT NE-SW ORIENTED COLD FRONT
SHOULD BE BI-SECTING THE ST LOUIS AREA AT 00Z WITH GUSTY NORTHWEST
WINDS IN ITS WAKE AND GOOD CAA...WHILE A THREAT OF SHOWERS AND
THUNDERSTORMS WILL PERSIST ALONG AND AHEAD OF IT. THE FRONT SHOULD
CLEAR THE CWA BY MIDNIGHT ENDING THE PRECIPITATION THREAT AS
WELL...WITH CLOUDS CLEARING 3-4 HOURS BEHIND IT.
GLASS
&&
.LONG TERM...
ISSUED AT 334 AM CDT MON SEP 17 2012
(TUESDAY THROUGH SATURDAY)
WE WILL HAVE A TASTE OF FALL TUESDAY INTO WEDNESDAY MORNING WITH
WELL BELOW AVERAGE TEMPERATURES. GUSTY NORTHWEST WINDS WILL MAKE
IT FEEL EVEN COOLER ON TUESDAY. HIGH PRESSURE WILL SLIDE ACROSS
THE AREA ON TUESDAY NIGHT WITH THE CENTER OF THE HIGH NEAR THE
BOOTHEEL BY DAYBREAK WEDNESDAY. IT APPEARS THE COOLEST LOWS SHOULD
BE ACROSS THE SOUTHEAST HALF OF THE CWA AND ESPECIALLY THE EASTERN
OZARKS. SOME PATCHY FROST IS NOT OUT OF THE QUESTION IN SOME
SHELTERED SPOTS IN THE OZARKS WHERE MINS COULD FALL TO 36-38 DEGS.
LOW LEVEL WAA QUICKLY GETS UNDERWAY LATER ON WEDNESDAY MORNING AS
THE HIGH RETREATS AS SOUTHERLY FLOW KICKS IN. ANOTHER COLD FRONT
MAKES AN ATTEMPT TO MOVE THROUGH THE AREA ON THURSDAY BUT IT
WASHES OUT AS SURFACE PRESSURES BEGIN FALLING ACROSS THE PLAINS.
ANOTHER MORE FORMIDABLE COLD FRONT SHOULD MOVE THROUGH THE AREA ON
FRIDAY WITH A REINFORCING SHOT OF COOLER AIR ON ITS HEELS ABOUT
12H LATER.
GLASS
&&
.AVIATION...
ISSUED AT 117 PM CDT MON SEP 17 2012
FRONTAL BOUNDARY MAKING SLOW PROGRESS TO THE SOUTH ACROSS MO THIS
AFTERNOON. FRONT IS NEAR KUIN AND SHOULD MOVE THROUGH KCOU BY 19Z
AND METRO AREA BY 22Z. AS FOR PCPN CHANCES WITH BOUNDARY...
SCATTERED IN NATURE AND HARD TO PIN DOWN...SO JUST WENT WITH VCNTY
WORDING. ONLY MENTION VCTS IN KUIN AND KCOU AS THEY SHOULD SEE
SOME BREAKS IN THE CLOUD COVER...SO A BIT MORE INSTABILITY THERE.
OTHERWISE...FEEL THAT CLOUD COVER OVER METRO AREA TO REMAIN...SO
WILL BE HARD TO RECOVER...SO JUST HAVE VCNTY SHOWER MENTION THERE.
AS FOR WINDS...TO VEER TO THE WEST AS BOUNDARY MOVES
THROUGH...THEN A FEW HOURS LATER...VEER TO THE NORTH AND PICKUP TO
AROUND 10 KTS WITH GUSTS TO 20 KTS AT TIMES. SKIES TO GRADUALLY
CLEAR OUT AND WINDS DIMINISH OVERNIGHT. GRADIENT TIGHTENS ON
TUESDAY AND BRISK WINDS MIX DOWN...SO WILL SEE NORTHWEST WINDS
AROUND 15 KTS...GUSTING TO AROUND 25KTS...WITH JUST SOME SCATTERED
DIURNAL CU.
SPECIFICS FOR KSTL...FRONTAL BOUNDARY MAKING SLOW PROGRESS TO THE
SOUTH ACROSS MO THIS AFTERNOON. FRONT TO MOVE THROUGH METRO AREA
BY 22Z. AS FOR PCPN CHANCES WITH BOUNDARY... SCATTERED IN NATURE
AND HARD TO PIN DOWN...SO JUST WENT WITH VCNTY SHOWER WORDING...AS
CLOUD COVER TO LINGER...SO WILL BE HARD TO RECOVER. AS FOR
WINDS...TO VEER TO THE WEST AS BOUNDARY MOVES THROUGH...THEN A FEW
HOURS LATER...AROUND 02Z TUESDAY...VEER TO THE NORTH AND PICKUP TO
AROUND 10 KTS WITH GUSTS TO 20 KTS AT TIMES. SKIES TO GRADUALLY
CLEAR OUT AND WINDS DIMINISH BY 07Z TUESDAY. GRADIENT TIGHTENS ON
TUESDAY AND BRISK WINDS MIX DOWN...SO WILL SEE NORTHWEST WINDS
AROUND 15 KTS...GUSTING TO AROUND 25KTS...WITH JUST SOME SCATTERED
DIURNAL CU AFTER 16Z TUESDAY.
BYRD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
652 AM CDT MON SEP 17 2012
.SHORT TERM...
ISSUED AT 334 AM CDT MON SEP 17 2012
(TODAY AND TONIGHT)
WHEN I WALKED IN THE DOOR AT 1000 PM LAST NIGHT I THOUGHT THE
FORECAST WAS GOING TO BE A BIT MORE CLEAR CUT THAN IT IS NOW. AREAS
OF DENSE FOG HAVE DEVELOPED OVERNIGHT...ESPECIALLY FROM ST LOUIS
NORTHWARD WHERE THERE ARE ONLY THIN HIGH CLOUDS AT THIS TIME.
MEANWHILE A PESKY AREA OF SHOWERS HAS ALSO DEVELOPED FROM SRN IL
ACROSS THE EASTERN OZARKS...APPARENTLY IN RESPONSE TO WEAK LOW
LEVEL WAA. VISIBILITIES HAVE IMPROVED SLIGHTLY IN THE ST LOUIS
AREA WITHIN THE LAST HOUR...AND THIS MAY BE DUE TO SOME THICKER
CLOUD COVER. I WILL HAVE TO MENTION SOME DENSE FOG THIS
MORNING...PROBABLY FROM I-70 NORTHWARD...BUT DONT HAVE ANY PLANS
FOR AN ADVISORY. THE PRECIPITATION TRENDS ARE A LITTLE MORE MURKY.
THE MODEL QPFS AND HRRR WANT TO KEEP A PERSIST THREAT OF SHOWERS
ACROSS THE SRN CWA THRU THE MORNING AND RAMPING UP INTO THE
AFTERNOON IN RESPONSE TO CONTINUED WAA AND LITTLE VORTS RIDING
ALONG THE NORTHERN FRINGE OF THE SHEAR AXIS THROUGH THE BOOTHEEL
REGION. MEANWHILE IT STILL LOOKS AS THOUGH THE AIR MASS ALONG AND
AHEAD OF THE ENCROACHING COLD FRONT WILL DESTABILIZE THIS
AFTERNOON AND THERE WILL BE SUFFICIENT FORCING FOR THE DEVELOPMENT
OF SCATTERED SHOWERS AND THUNDERSTORMS AND POSSIBLY A BROKEN LINE
FROM EASTERN MO INTO IL. THE POTENT NE-SW ORIENTED COLD FRONT
SHOULD BE BI-SECTING THE ST LOUIS AREA AT 00Z WITH GUSTY NORTHWEST
WINDS IN ITS WAKE AND GOOD CAA...WHILE A THREAT OF SHOWERS AND
THUNDERSTORMS WILL PERSIST ALONG AND AHEAD OF IT. THE FRONT SHOULD
CLEAR THE CWA BY MIDNIGHT ENDING THE PRECIPITATION THREAT AS
WELL...WITH CLOUDS CLEARING 3-4 HOURS BEHIND IT.
GLASS
&&
.LONG TERM...
ISSUED AT 334 AM CDT MON SEP 17 2012
(TUESDAY THROUGH SATURDAY)
WE WILL HAVE A TASTE OF FALL TUESDAY INTO WEDNESDAY MORNING WITH
WELL BELOW AVERAGE TEMPERATURES. GUSTY NORTHWEST WINDS WILL MAKE
IT FEEL EVEN COOLER ON TUESDAY. HIGH PRESSURE WILL SLIDE ACROSS
THE AREA ON TUESDAY NIGHT WITH THE CENTER OF THE HIGH NEAR THE
BOOTHEEL BY DAYBREAK WEDNESDAY. IT APPEARS THE COOLEST LOWS SHOULD
BE ACROSS THE SOUTHEAST HALF OF THE CWA AND ESPECIALLY THE EASTERN
OZARKS. SOME PATCHY FROST IS NOT OUT OF THE QUESTION IN SOME
SHELTERED SPOTS IN THE OZARKS WHERE MINS COULD FALL TO 36-38 DEGS.
LOW LEVEL WAA QUICKLY GETS UNDERWAY LATER ON WEDNESDAY MORNING AS
THE HIGH RETREATS AS SOUTHERLY FLOW KICKS IN. ANOTHER COLD FRONT
MAKES AN ATTEMPT TO MOVE THROUGH THE AREA ON THURSDAY BUT IT
WASHES OUT AS SURFACE PRESSURES BEGIN FALLING ACROSS THE PLAINS.
ANOTHER MORE FORMIDABLE COLD FRONT SHOULD MOVE THROUGH THE AREA ON
FRIDAY WITH A REINFORCING SHOT OF COOLER AIR ON ITS HEELS ABOUT
12H LATER.
GLASS
&&
.AVIATION...
ISSUED AT 630 AM CDT MON SEP 17 2012
COMPLEX FORECAST IN STORE FOR THE NEXT 12 TO 18 HOURS. AREA OF
FG/ST SHUD CONTINUE TO MOVE N THIS MORNING WITH FG GRADUALLY
MOVING OUT OF THE REGION AND REPLACED BY ST. CIGS SHUD LIFT THRU
THE MORNING...BUT MAY BE SLOW TO LIFT UNTIL THIS AFTERNOON. EXPECT
TSRA TO DEVELOP TODAY WITH THE BEST CHANCES THIS AFTERNOON.
HOWEVER...WITH A WEAK CAP IN PLACE...SCT TSRA MAY DEVELOP LATE
THIS MORNING AHEAD OF THE APPROACHING CDFNT. BEHIND THE
CDFNT...BELIEVE ANOTHER ROUND OF LOW END MVFR CIGS WILL DEVELOP
WITH GUSTY NLY WINDS. WINDS WILL GRADUALLY DIMINISH LATE TONIGHT
WITH CLOUDS CLEARING.
SPECIFICS FOR KSTL...AREA OF SHRA CURRENTLY TO THE S OF TERMINAL
MAY IMPACT TERMINAL AROUND 14Z...BUT MAY REMAIN JUST E OF SITE.
EXPECT LOW MVFR CIGS...AND POSSIBLY IFR CIGS TO REACH TERMINAL
WITH OR JUST AFTER PRECIP. THESE CIGS SHUD GRADUALLY LIFT THIS
MORNING...BUT WILL LIKELY BE SLOW TO DO SO. EXPECT TSRA TO DEVELOP
AND IMPACT THE TERMINAL THIS AFTERNOON. HOWEVER...TIMING IS STILL
UNCERTAIN AS TSRA MAY DEVELOP AHEAD OF THE APPROACHING CDFNT.
EXPECT LOW MVFR CIGS AGAIN BEHIND THE FNT WITH GUSTY NLY WINDS.
WINDS SHUD GRADUALLY DIMINISH WITH CIGS BECOMING VFR LATE TONIGHT.
TILLY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
343 AM CDT MON SEP 17 2012
.SHORT TERM...
ISSUED AT 334 AM CDT MON SEP 17 2012
(TODAY AND TONIGHT)
WHEN I WALKED IN THE DOOR AT 1000 PM LAST NIGHT I THOUGHT THE
FORECAST WAS GOING TO BE A BIT MORE CLEAR CUT THAN IT IS NOW. AREAS
OF DENSE FOG HAVE DEVELOPED OVERNIGHT...ESPECIALLY FROM ST LOUIS
NORTHWARD WHERE THERE ARE ONLY THIN HIGH CLOUDS AT THIS TIME.
MEANWHILE A PESKY AREA OF SHOWERS HAS ALSO DEVELOPED FROM SRN IL
ACROSS THE EASTERN OZARKS...APPARENTLY IN RESPONSE TO WEAK LOW
LEVEL WAA. VISIBILITIES HAVE IMPROVED SLIGHTLY IN THE ST LOUIS
AREA WITHIN THE LAST HOUR...AND THIS MAY BE DUE TO SOME THICKER
CLOUD COVER. I WILL HAVE TO MENTION SOME DENSE FOG THIS
MORNING...PROBABLY FROM I-70 NORTHWARD...BUT DONT HAVE ANY PLANS
FOR AN ADVISORY. THE PRECIPITATION TRENDS ARE A LITTLE MORE MURKY.
THE MODEL QPFS AND HRRR WANT TO KEEP A PERSIST THREAT OF SHOWERS
ACROSS THE SRN CWA THRU THE MORNING AND RAMPING UP INTO THE
AFTERNOON IN RESPONSE TO CONTINUED WAA AND LITTLE VORTS RIDING
ALONG THE NORTHERN FRINGE OF THE SHEAR AXIS THROUGH THE BOOTHEEL
REGION. MEANWHILE IT STILL LOOKS AS THOUGH THE AIR MASS ALONG AND
AHEAD OF THE ENCROACHING COLD FRONT WILL DESTABILIZE THIS
AFTERNOON AND THERE WILL BE SUFFICIENT FORCING FOR THE DEVELOPMENT
OF SCATTERED SHOWERS AND THUNDERSTORMS AND POSSIBLY A BROKEN LINE
FROM EASTERN MO INTO IL. THE POTENT NE-SW ORIENTED COLD FRONT
SHOULD BE BI-SECTING THE ST LOUIS AREA AT 00Z WITH GUSTY NORTHWEST
WINDS IN ITS WAKE AND GOOD CAA...WHILE A THREAT OF SHOWERS AND
THUNDERSTORMS WILL PERSIST ALONG AND AHEAD OF IT. THE FRONT SHOULD
CLEAR THE CWA BY MIDNIGHT ENDING THE PRECIPITATION THREAT AS
WELL...WITH CLOUDS CLEARING 3-4 HOURS BEHIND IT.
GLASS
&&
.LONG TERM...
ISSUED AT 334 AM CDT MON SEP 17 2012
(TUESDAY THROUGH SATURDAY)
WE WILL HAVE A TASTE OF FALL TUESDAY INTO WEDNESDAY MORNING WITH
WELL BELOW AVERAGE TEMPERATURES. GUSTY NORTHWEST WINDS WILL MAKE
IT FEEL EVEN COOLER ON TUESDAY. HIGH PRESSURE WILL SLIDE ACROSS
THE AREA ON TUESDAY NIGHT WITH THE CENTER OF THE HIGH NEAR THE
BOOTHEEL BY DAYBREAK WEDNESDAY. IT APPEARS THE COOLEST LOWS SHOULD
BE ACROSS THE SOUTHEAST HALF OF THE CWA AND ESPECIALLY THE EASTERN
OZARKS. SOME PATCHY FROST IS NOT OUT OF THE QUESTION IN SOME
SHELTERED SPOTS IN THE OZARKS WHERE MINS COULD FALL TO 36-38 DEGS.
LOW LEVEL WAA QUICKLY GETS UNDERWAY LATER ON WEDNESDAY MORNING AS
THE HIGH RETREATS AS SOUTHERLY FLOW KICKS IN. ANOTHER COLD FRONT
MAKES AN ATTEMPT TO MOVE THROUGH THE AREA ON THURSDAY BUT IT
WASHES OUT AS SURFACE PRESSURES BEGIN FALLING ACROSS THE PLAINS.
ANOTHER MORE FORMIDABLE COLD FRONT SHOULD MOVE THROUGH THE AREA ON
FRIDAY WITH A REINFORCING SHOT OF COOLER AIR ON ITS HEELS ABOUT
12H LATER.
GLASS
&&
.AVIATION...
ISSUED AT 1139 PM CDT SUN SEP 16 2012
MVFR TO IFR FOG AND STRATUS ARE EXPECTED TO PERSIST AT THE
TERMINALS OVERNIGHT BEFORE CONDITIONS IMPROVE WITH DIURNAL MIXING
BY MID TO LATE MORNING TOMORROW. THERE IS A CHANCE OF PCPN
TOMORROW AS A CDFNT APPROACHES AND MOVES THROUGH THE REGION
HOWEVER CONFIDENCE IN THE TIMING REMAINS LOW ATTM. SEVERAL HOURS
OF GUSTY NNWLY WINDS ARE EXPECTED SHORTLY AFTER FROPA DUE TO THE
TIGHT PRESSURE GRADIENT.
SPECIFICS FOR KSTL...MVFR TO IFR FOG AND STRATUS ARE EXPECTED TO
PERSIST OVERNIGHT BEFORE CONDITIONS IMPROVE WITH DIURNAL MIXING
BY MID TO LATE MORNING TOMORROW. THERE IS A CHANCE OF PCPN
TOMORROW AS A CDFNT APPROACHES AND MOVES THROUGH THE REGION
HOWEVER CONFIDENCE IN THE TIMING REMAINS LOW ATTM. SEVERAL HOURS
OF GUSTY NNWLY WINDS ARE EXPECTED SHORTLY AFTER FROPA DUE TO THE
TIGHT PRESSURE GRADIENT.
KANOFSKY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
751 PM EDT TUE SEP 18 2012
.SYNOPSIS...
A COLD FRONT WILL SLOWLY PUSH ACROSS THE REGION TONIGHT...WITH
RAIN AND GUSTY WINDS SUBSIDING BY LATER THIS EVENING. HIGH
PRESSURE WILL BUILD IN...BRINGING DRY WEATHER FROM WEDNESDAY
THROUGH FRIDAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
610PM...REMOVED ENTIRE REMAINING REGION OF TORNADO WATCH.
SIGNIFICANT CONVECTION HAS MOVED EAST OF THE REGION. WHILE SRH
VALUES REMAIN EXTREME, INSTABILITY NEVER MATERIALIZED TO SUPPORT
CONVECTION.
5PM...REMOVED WESTERN PORTION OF TORNADO WATCH WHERE
RAIN COOLED AIR AS STABILIZED ATMOSPHERE QUITE A BIT, AND WIND
SHEAR HAS DECREASED. WILL CONTINUE EASTERN PORTION FOR AT LEAST
THE NEXT HOUR.
330 PM UPDATE... WE APPEAR TO BE TRANSITIONING FROM A SVR/WIND
THREAT...TO MORE OF A HVY RAIN THREAT ATTM.
THE BACK EDGE OF THE PRE-FRNTL BAND OF RAIN/EMBEDDED TSRA IS
SLOWLY PUSHING EWD FROM ABT THE I-81 CORRIDOR LATE THIS AFTN. THE
MAIN CONCERN IS TURNING TO A TRAINING SW-NE BATCH OF
+RA/TSRA...EXTENDING FROM S-CNTRL PA UP INTO OUR SERN ZNS...SO FF
WATCHES HAVE BEEN POSTED FOR LUZERNE/LACK/WAYNE/PIKE/SULL CNTYS. SINCE
THE LEADING NRN STREAM WV IS LIFTING OUT TO THE NE THROUGH
ONT...IT WILL LIKELY TAKE THE SECOND WV COMING IN BEHIND IT FROM
WI/UPR MI...TO FINALLY KICK THE HVYR RAIN BAND EWD AFTER 00Z.
AS FOR THE WIND/SVR SITN...STG SYNOPTIC-SCALE WINDS ARE PUSHING
EWD ATTM...AND THE OVERALL WIND THREAT SHOULD BE LWRG WITH TIME
TWDS 00Z. DITTO FOR THE SVR CONVECTIVE SITN.
LTR TNT...DRIER AIR WILL ULTIMATELY PUSH IN FROM THE W...WITH POPS
DIMINISHING BY/AFTER 06Z.
PREV DISC... 1230 PM UPDATE... TOR WATCH #643 ISSUED FOR NE PA
AND SULL CNTY NY...TIL 23Z. THUS...WE`VE ADDED SOME ENHANCED
WORDING FOR THE ISOLD TSRA THIS AREA.
LINEAR FEATURES ARE BCMG MORE PROMINENT ALG THE BACK EDGE OF THE
STEADIER PCPN...AS ALLUDED TO IN PREV DISC. ML CAPES REMAIN FAIRLY
LOW...ON THE ORDER OF 100-200...BUT LOW-LVL SHEAR IS EXTREMELY
IMPRESSIVE (0-1 KM SREL HEL OF 400+). UNLESS MORE DESTAB
OCCURS...DISCRETE CELL DVLPMT IS UNLIKELY...BUT LINES OF
SHRA/EMBEDDED TSRA...WITH LOCALIZED 50+ KT GUSTS ARE PLAUSIBLE.
WE`LL CONTINUE TO MONITOR CLOSELY.
PREV DISC... 10 AM UPDATE... BROAD SWATH OF RA/+RA CONTS TO TRACK
NEWD THROUGH CNY/NE PA ATTM...BEING FUELED BY STG POS THETA-E
ADVCTN ON THE LEADING EDGE OF AN INCRG LOW-LVL JET. WE EXPECT
STEADY RAIN TO PERSIST TIL PERHAPS MID TO LATE AFTN...WHEN THE
BACK EDGE OF THE MAIN PCPN SHIELD...NOW ACRS WRN PA...ATTEMPTS TO
MOVE INTO THE CWA FROM SW TO NE. A BIG QUESTION IS WHAT HAPPENS
AFTER THAT...JUST AHD OF THE COLD FROPA IN THE 21Z-01Z TIME FRAME.
MOST OF THE CONVECTION ALLOWING MODELS (HRRR AND 4 KM WRF...FOR
EXAMPLE) INDICATE THAT SOME SORT OF ENHANCED/CONVECTIVE LN FORMS
ON THE BACK EDGE OF THE STEADIER PCPN AFTER 21Z...TRANSLATING
MAINLY ACRS NE PA AND PTNS OF THE SRN TIER LATE IN THE DAY.
THIS...OF COURSE...WILL DEPEND ON HOW MUCH INSTAB CAN FORM. THE
LATEST RUC SHOWS ML CAPE OF 200-400 THIS TIME FRAME IN OUR SERN
ZNS...WITH THE 12Z NAM COMING IN SHOWING MORE (500-800). GIVEN
EXTENSIVE CLOUD COVER/PCPN FOR SVRL MORE HRS AT LEAST...AND WHAT`S
BEING OBSERVED UPSTREAM ON SPC MESO`S ATTM (ML CAPE OF 100-200 IN
SE PA)...WE`RE INCLINED TO BUY THE MORE CONSERVATIVE RUC. ACRS
ROUGHLY THE SERN HALF OF THE CWA...WE`LL STILL MENTION ISOLD
TSRA...WHILE SHOWING OCNL +RA JUST ABT EVERYWHERE. THE BEST SVR
POTENTIAL APPEARS TO BE JUST SE OF THE CWA...WHERE THE PRIMARY
IMPETUS FOR ANY DISCERNIBLE LN OR DISCRETE CELL FORMATION IS.
KBGM VWP HAS 20-30 KT SRLY FLOW AT 2K FT AGL ATTM...WITH 40-50 KT
AT 3-4K FT AGL. KBGM BASE VEL PRODS ALSO SHOW THE 50-60 KT CORE
MOVG NWD THROUGH ERN PA...AND DESCENDING SOMEWHAT WITH TIME. THE
MOST FAVORABLE TIME FOR CONSISTENTLY STG GRADIENT WIND GUSTS WILL BE
FROM ABT 17-22Z. WIND ADVISORIES REMAIN IN TACT.
UNLESS TRAINING OF HEAVY RAIN BANDS FORM...WE`RE STILL NOT
EXPECTING ANY SIG HYDRO RELATED PROBLEMS...SO NO WATCHES PLANNED
FOR THE TIME BEING.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY NIGHT/...
340 PM UPDATE... VERY BRIEF DISCN...DUE TO ONGOING SVR WX.
DRY WX STILL ANTICIPATED WED-FRI...OTHER THAN SOME ISOLD -SHRA
EARLY WED...DUE TO A WEAK LAKE RESPONSE.
TEMPS WILL BE UNCHANGED...AS CURRENT MAX/MIN TEMP GRIDS MATCH
BLENDED MOS WELL.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
730 PM UPDATE...LATE UPDATE TODAY WITH THE SEVERE WEATHER AND
FLASH FLOOD THREATS FROM EARLIER AND ONGOING. THE FORECAST GRIDS
WERE SENT OVER EARLIER THIS AFTERNOON AND NOW HERE ARE THE DETAILS.
BOTH THE EURO AND GFS ARE CONSISTENT IN SHOWING AN UPPER LEVEL
TROF MOVING INTO THE CWA SATURDAY INTO EARLY SUNDAY...KEEPING OUR
WEATHER UNSETTLED WITH SHOWERS. BOTH MODELS STILL HINT OUT SOME
SLIGHT IMPROVEMENT LATER SUNDAY INTO MONDAY AS THE MAIN WAVE LIFTS
FAR ENOUGH NORTH TO GET OUR CWA INTO A DRY SLOT. THE EXCEPTION MAY
BE ACROSS THE FAR NORTH WHERE SHOWERS MAY STILL LINGER WITH THE
CLOSER PROXIMITY TO THE LOW.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
A COLD FRONT IS MOVING THROUGH THE TERMINALS NOW...ROUGHLY ALONG
AND NEAR A LINE FROM KSYR SOUTH TO KITH AND KELM. THROUGH 01Z
ACROSS THE NY TERMINALS...BRIEF MVFR VSBYS POSSIBLE IN SHOWERS
WITH THE FRONTAL PASSAGE. WINDS WILL SHIFT FROM SOUTHWEST TO WEST
AND BECOME GUSTY WITH SUSTAINED WINDS 10 KTS AND GUSTS UP TO 25
KTS WITH THE FRONTAL PASSAGE ITSELF. VFR CIGS AHEAD OF THE FRONT WILL
QUICKLY DROP TO MVFR DURING THIS TIME...AND BECOME PREVAILING
THROUGH 04Z TO 07Z. SOME IFR IS STILL POSSIBLE AT KITH AND KBGM.
CONFIDENCE IS HIGH THAT WE WILL SEE AT LEAST SOME IFR HERE BUT
BASED ON SPOTTY IFR TO THE NORTH AND WEST...I WAS NOT CONFIDENT
ENOUGH TO PREVAIL IT. VFR CONDITIONS RETURN AFTER 06Z. FOG DOES
NOT APPEAR TO BE LIKELY AT KELM WITH STRONG BOUNDARY LAYER MIXING.
FARTHER SOUTH AT KAVP...MVFR CIGS POSSIBLE AHEAD OF THE FRONT
ITSELF...WITH A FROPA MORE IN THE 01Z TO 02Z RANGE. HERE BRIEF
MVFR VSBYS ALSO POSSIBLE IN SHOWERS BUT NOT QUITE AS LIKELY AS
WITH THE NY TERMINALS. LIGHT SOUTHWEST WINDS AT LESS THAN 10 KTS
MAY GUST TO 20 KTS AS WIND SHIFT INTO THE WEST WITH THE FROPA
THROUGH 04Z. MVFR CIGS LIKELY TO DEVELOP EARLY THIS EVENING AND
PERSIST THE LONGEST (THROUGH 08Z) WITH THE CLOSER PROXIMITY TO THE DEPARTING
FRONT. VFR CONDITIONS DEVELOPING TOWARD 12Z.
VFR WEDNESDAY WITH BKN TO SCT CIGS 4KFT TO 6KFT AND NORTHWEST
WINDS 5 T0 10 KTS.
OUTLOOK...
THU/FRI...VFR EXCEPT IFR FOG AT KELM EACH MORNING FROM 8 TO 14Z.
SAT...MVFR POSSIBLE IN SHOWERS.
SUN...GENERALLY VFR...MVFR POSSIBLE NORTH IN SHOWERS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR PAZ040-044-
047-048-072.
WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR PAZ048.
NY...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR NYZ062.
WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR NYZ046-057-062.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...DJP/MLJ
SHORT TERM...MLJ
LONG TERM...HEDEN
AVIATION...HEDEN
AREA FORECAST DISCUSSION
NWS BUFFALO NY
323 PM EDT MON SEP 17 2012
.SYNOPSIS...
HIGH PRESSURE OFF THE MID ATLANTIC COAST WILL SUPPLY OUR REGION WITH
ONE MORE BEAUTIFUL DAY AS TEMPERATURES WILL SOAR WELL ABOVE NORMAL.
CONDITIONS WILL THEN DETERIORATE TONIGHT AS A COMPLEX STORM SYSTEM
WILL APPROACH FROM THE OHIO VALLEY. THE MOISTURE RICH SYSTEM WILL
SPREAD A SOAKING RAIN ACROSS OUR REGION LATE TONIGHT AND TUESDAY...
WITH SOME SITES PICKING UP OVER AN INCH OF RAIN. HIGH PRESSURE WILL
BRING US A CRISP FALL LIKE DAY FOR WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
IDEAL LATE SUMMER WEATHER IS ON TAP FOR THE REST OF THE DAY AS
HIGH PRESSURE ANCHORED OFF THE MIDDLE ATLANTIC COAST REMAINS IN
CONTROL. SUBSIDENCE...COUPLED WITH A FAIRLY DRY AIRMASS...WILL
RESULT IN MOSTLY SUNNY SKIES...ALTHOUGH THERE WILL BE SOME
FAIR WEATHER CU...ESPECIALLY ACROSS THE GENESEE VALLEY AND FINGER
LAKES WHERE STEEPER LOW LEVEL LAPSE RATES ARE IN PLACE.
THE SOUTHERLY FLOW BETWEEN THE SURFACE HIGH AND THE MIDWEST COLD
FRONT WILL ALLOW TEMPERATURES TO WARM WELL INTO THE 70S...AND
POSSIBLY 80 DEGREES IN SOME OF THE WARMER VALLEYS. THESE READINGS
WILL BE AT LEAST 10 DEG ABOVE NORMAL.
CLOUDS WILL THEN INCREASE AND THICKEN ACROSS OUR AREA TONIGHT AS A
VERY ENERGETIC...COMPLEX STORM SYSTEM APPROACHES FROM THE OHIO VALLEY.
RICH GULF MOISTURE POOLING OVER THE SOUTHERN STATES AHEAD OF THE
DEVELOPING STORM SYSTEM WILL BE WHISKED NORTHWARDS WITHIN H85-70
WINDS OF 70-80 KTS. THE CORE OF THESE WINDS WILL BE SOUTH OF OUR
REGION TONIGHT...BUT ARE FORECAST TO MOVE OVER EASTERN NEW YORK ON
TUESDAY. THESE EXTREMELY ANOMALOUS WINDS WILL BE AS MUCH AS 5
STANDARD DEVIATIONS FROM NORMAL IN THEIR STRENGTH...WHICH EQUATE TO
AN EVENT THAT HAS LESS THAN ONE HALF OF A PERCENT CHANCE OF
OCCURRENCE FOR THE PARTICULAR CALENDAR DAY.
THE COMPLEX STORM SYSTEM ITSELF WILL FEATURE A WAVY FRONTAL BOUNDARY
THAT WILL EVENTUALLY INCLUDE A DEEPENING SFC LOW. THE BURGEONING LOW
WILL RIDE ALONG THE FRONT AND LIFT FROM ABOUT WEST VIRGINIA LATE
TONIGHT TO OUR FINGER LAKES ON TUESDAY. A POTENT SHORTWAVE DIVING
INTO THE BASE OF A DIGGING H5 TROUGH OVER THE UPPER MISSISSIPPI
VALLEY WILL ENERGIZE THIS SFC WAVE...WHILE A H25 JET OF 140 KTS OVER
THE UPPER GREAT LAKES WILL PLACE OUR FORECAST AREA UNDER THE
INFLUENCE OF THE JET ENTRANCE REGION. THE COMBINATION OF THE LIFT
FROM THE RR QUAD OF THE H25 JET...THE STRONG LOW LEVEL JET AND
STEADY HGT FALLS WILL PRODUCE DEEP ASCENT FOR THE MOISTURE RICH
AIRMASS. PWAT VALUES WILL INCREASE TO MORE THAN 1.5" FOR MOST SITES.
BREAKING THIS DOWN INTO A FORECAST FOR TONIGHT...RAIN SHOULD
APPROACH THE NEW YORK PENNSYLVANIA LINE AROUND MIDNIGHT...THEN
SPREAD NORTH-NORTHEAST DURING THE REMAINING OVERNIGHT HOURS. THE
RAIN SHOULD REACH THE THOUSANDS ISLAND REGION BY ABOUT DAYBREAK.
BECAUSE OF THE STRONG SOUTHERLY FLOW ALOFT...TEMPS SHOULD REMAIN
WELL ABOVE SEASONAL VALUES TONIGHT WITH LOWS ONLY FORECAST TO DROP
TO WITHIN A COUPLE DEGREES OF 60. NEAR LAKE ERIE AND OVER PARTS OF
THE IAG FRONTIER...LOWS MAY BE CLOSER TO 65. AGAIN...THESE VALUES
WILL BE 10 OR MORE DEG F ABOVE NORMAL.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY NIGHT/...
DEEP MOISTURE WILL BE ON ITS WAY OUT AT THE START OF THE PERIOD...
AS THE SURFACE LOW WILL BE IN THE PROCESS OF LIFTING INTO EASTERN
CANADA AND THE COLD FRONT WILL BE PUSHING EAST OF THE AREA. STILL
COULD BE LOOKING AT THE BACK EDGE OF A HEAVY RAIN AREA ACROSS
EASTERN SECTIONS TUESDAY EVENING...BUT THIS SHOULD EXIT THE ENTIRE
AREA BEFORE MIDNIGHT. ONCE THE HEAVY RAIN AREA MOVES
OUT...INCREASING OVER-LAKE INSTABILITY IN A STRONG COLD AIR
ADVECTION REGIME WILL KEEP A CONTINUED THREAT FOR LAKE INDUCED
SHOWERS TO THE LEE OF THE LAKES...ESPECIALLY IN FAVORED
WEST-NORTHWEST FLOW AREAS. THE ARRIVAL OF A MUCH COOLER AIRMASS WILL
SEND OVERNIGHT LOWS INTO THE 40S...ALTHOUGH THEY COULD REMAIN IN THE
LOWER 50S ALONG THE MOST IMMEDIATE LAKESHORE AREAS.
LINGERING OVER-LAKE INSTABILITY WILL END WEDNESDAY MORNING AS
INCREASING SUBSIDENCE AND DRIER AIR WORK INTO THE REGION...AS A
SURFACE HIGH PRESSURE NOSES IN FROM THE SOUTHWEST. CHILLY DAY IN
STORE WITH MOST HIGHS IN THE UPPER 50S TO LOWER 60S.
MODELS CONCUR THAT HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH
THURSDAY WITH A FAIR WEATHER DAY. STRENGTHENING WARM AIR ADVECTION
WILL BRING HELP REBOUND TEMPERATURES BACK INTO THE UPPER 60S TO
LOWER 70S.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
THE UPPER LEVEL PATTERN WILL BECOME HIGHLY AMPLIFIED THIS
PERIOD...AS A LONG WAVE TROUGH DEEPENS OVER THE EASTERN CONUS. A
BLOCKING PATTERN WILL HELP KEEP THE MAIN TROUGH AXIS FROM LIFTING
NORTHEAST...AS A SERIES OF SHORT WAVES DROP RAPIDLY SOUTHEAST OUT
OF CANADA INTO THE MAIN TROUGH OVER THE WESTERN GREAT LAKES
REGION.
LATEST MODELS SUGGESTING THAT A SHORTWAVE WILL PUSH ACROSS THE
NORTHERN GREAT LAKES LATE THURSDAY THEN INTO CANADA BY FRIDAY. THE
ASSOCIATED COLD FRONT WILL MAKE AN ATTEMPT TO APPROACH THE
REGION...BUT LOOKS TO GET HUNG UP IN AN UNFAVORABLE UPPER LEVEL FLOW
PATTERN. THIS BOUNDARY LOOKS TO DISSIPATE BEFORE IT REACHES THE
AREA. MOISTURE AND DYNAMICS REMAIN TO OUR NORTHWEST THEREFORE WE
SHOULD SEE LITTLE IF ANY PRECIPITATION ASSOCIATED WITH THIS FEATURE.
FRIDAY SHOULD BE THE WARMEST DAY OF THE WEEK WITH MOST HIGHS IN THE
MID TO UPPER 70S.
LATEST MEDIUM RANGE GUIDANCE AND ENSEMBLES CONTINUING TO INSIST
ON A RE-ENERGIZED COLD FRONT CROSSING THE AREA AT THE START OF THE
PERIOD. ALTHOUGH NOT A WASHOUT...THERE WILL BE A CHANCE OF
SCATTERED SHOWERS FRIDAY NIGHT AND SATURDAY WITH THE PASSAGE OF
THIS BOUNDARY. WEAK HIGH PRESSURE WILL BUILD ACROSS THE REGION IN
WAKE OF THE FRONT. HOWEVER...CYCLONIC FLOW PERSISTING ALOFT WILL
ALLOW FOR ADDITIONAL SHOWER DEVELOPMENT SATURDAY NIGHT AND SUNDAY.
COOLING 850 MB TEMPERATURES ALONG WITH WARM LAKE TEMPERATURES WILL
CREATE DELTA T/S NEAR 20C WHICH SHOULD SUPPORT RESPONSES OFF BOTH
LAKES. CYCLONIC FLOW DIMINISHES BY THE END OF THE PERIOD...AS
DRIER AIR BUILDS OVER THE LOWER LAKES WHICH SHOULD BRING IMPROVING
CONDITIONS FOR MONDAY. PATTERN ALOFT WOULD FAVOR GENERALLY BELOW
NORMAL TEMPERATURES THROUGH THE PERIOD.
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
HIGH PRESSURE CENTERED ALONG THE MID ATLANTIC COAST WILL KEEP FAIR
VFR WEATHER IN PLACE THROUGH THE FIRST HALF OF TONIGHT.
LATER TONIGHT AND TUESDAY...MOISTURE TRACKING NORTH FROM THE
TENNESSEE VALLEY WILL INTERACT WITH A COLD FRONT MOVING EAST FROM THE
CENTRAL GREAT LAKES. AS THIS RAIN OVERSPREADS THE AREA...MVFR
CONDITIONS WILL DEVELOP...WITH IFR CONDITIONS LIKELY ACROSS THE
SOUTHERN TIER. AFTER THE COLD FRONT CROSSES THE WESTERN TAF SITES
DURING THE AFTERNOON...EXPECT IFR CONDITIONS TO BECOME MORE
WIDESPREAD.
SOME LOW LEVEL WIND SHEAR HAS BEEN ADDED TO THE TAF SITES LATE
TONIGHT AND TUESDAY MORNING. AS A POTENT LOW LEVEL JET PUSHES EAST
ACROSS WESTERN AND CENTRAL NEW YORK. THE BEST CHANCES FOR LLWS WILL
BE FROM KROC TO KART.
OUTLOOK...
TUESDAY NIGHT...MVFR/IFR IMPROVING TO MVFR/VFR WITH -RA TAPERING OFF
FROM WEST TO EAST.
WEDNESDAY...IMPROVING TO VFR.
THURSDAY AND FRIDAY...MAINLY VFR.
SATURDAY...MAINLY VFR WITH CHANCE -SHRA.
&&
.MARINE...
WHILE HIGH PRESSURE ANCHORED OFF THE MIDDLE ATLANTIC COAST SHOULD
KEEP CONDITIONS BELOW SMALL CRAFT ADVISORY CRITERIA TODAY...WATERS
WILL BE QUITE CHOPPY ACROSS THE EASTERN PART OF LAKE ONTARIO THIS
MORNING AND THEN OVER PARTS OF LAKE ERIE DURING THE MIDDAY AND EARLY
AFTERNOON. IN THOSE AREAS...MODERATE SOUTHERLIES WILL PRODUCE WAVES
OF 2 TO 4 FEET SO THEY WILL HAVE TO BE CLOSELY WATCHED.
WINDS AND WAVES WILL BRIEFLY SUBSIDE ON BOTH LAKES THIS EVENING...
THEN A COMPLEX STORM SYSTEM WILL APPROACH THE LOWER GREAT LAKES
DURING THE OVERNIGHT. WINDS AHEAD OF THIS STORM SYSTEM WILL FRESHEN
OVER EASTERN LAKE ONTARIO LATER TONIGHT...POSSIBLY PRODUCING SCA
CONDITIONS BY DAYBREAK TUESDAY.
STRONGER WINDS ARE EXPECTED IN THE WAKE OF THE STORM SYSTEM TUESDAY
AFTERNOON AND NIGHT WITH FRESH WEST TO NORTHWEST BREEZES PRODUCING
SCA CONDITIONS ACROSS MUCH OF LAKE ONTARIO AND POSSIBLY FOR A SHORT
TIME...ON LAKE ERIE.
HIGH PRESSURE WILL MOVE IN ON WEDNESDAY TO PROMOTE WEAKER WINDS AND
LOWER WAVES.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 PM TUESDAY TO 11 AM EDT WEDNESDAY
FOR LEZ040-041.
SMALL CRAFT ADVISORY FROM 8 PM TUESDAY TO 2 PM EDT
WEDNESDAY FOR LOZ043-044.
SMALL CRAFT ADVISORY FROM 6 PM TUESDAY TO 11 AM EDT
WEDNESDAY FOR LOZ042.
SMALL CRAFT ADVISORY FROM 2 AM TO 7 AM EDT TUESDAY FOR
LOZ045.
SMALL CRAFT ADVISORY FROM 8 AM TUESDAY TO 8 AM EDT
WEDNESDAY FOR LOZ045.
&&
$$
SYNOPSIS...RSH
NEAR TERM...RSH/TJP
SHORT TERM...TMA
LONG TERM...TMA
AVIATION...TJP
MARINE...RSH
AREA FORECAST DISCUSSION
NWS BUFFALO NY
146 PM EDT MON SEP 17 2012
.SYNOPSIS...
HIGH PRESSURE OFF THE MID ATLANTIC COAST WILL SUPPLY OUR REGION WITH
ONE MORE BEAUTIFUL DAY AS TEMPERATURES WILL SOAR WELL ABOVE NORMAL.
CONDITIONS WILL THEN DETERIORATE TONIGHT AS A COMPLEX STORM SYSTEM
WILL APPROACH FROM THE OHIO VALLEY. THE MOISTURE RICH SYSTEM WILL
SPREAD A SOAKING RAIN ACROSS OUR REGION LATE TONIGHT AND TUESDAY...
WITH SOME SITES PICKING UP OVER AN INCH OF RAIN. HIGH PRESSURE WILL
BRING US A CRISP FALL LIKE DAY FOR WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
IDEAL LATE SUMMER WEATHER IS ON TAP FOR THE REST OF THE DAY AS
HIGH PRESSURE ANCHORED OFF THE MIDDLE ATLANTIC COAST REMAINS IN
CONTROL. SUBSIDENCE...COUPLED WITH A FAIRLY DRY AIRMASS...WILL
RESULT IN MOSTLY SUNNY SKIES...ALTHOUGH THERE WILL BE SOME
FAIR WEATHER CU...ESPECIALLY ACROSS THE GENESEE VALLEY AND FINGER
LAKES WHERE STEEPER LOW LEVEL LAPSE RATES ARE IN PLACE.
THE SOUTHERLY FLOW BETWEEN THE SURFACE HIGH AND THE MIDWEST COLD
FRONT WILL ALLOW TEMPERATURES TO WARM WELL INTO THE 70S...AND
POSSIBLY 80 DEGREES IN SOME OF THE WARMER VALLEYS. THESE READINGS
WILL BE AT LEAST 10 DEG ABOVE NORMAL.
CLOUDS WILL THEN INCREASE AND THICKEN ACROSS OUR AREA TONIGHT AS A
VERY ENERGETIC...COMPLEX STORM SYSTEM APPROACHES FROM THE OHIO VALLEY.
RICH GULF MOISTURE POOLING OVER THE SOUTHERN STATES AHEAD OF THE
DEVELOPING STORM SYSTEM WILL BE WHISKED NORTHWARDS WITHIN H85-70
WINDS OF 70-80 KTS. THE CORE OF THESE WINDS WILL BE SOUTH OF OUR
REGION TONIGHT...BUT ARE FORECAST TO MOVE OVER EASTERN NEW YORK ON
TUESDAY. THESE EXTREMELY ANOMALOUS WINDS WILL BE AS MUCH AS 5
STANDARD DEVIATIONS FROM NORMAL IN THEIR STRENGTH...WHICH EQUATE TO
AN EVENT THAT HAS LESS THAN ONE HALF OF A PERCENT CHANCE OF
OCCURRENCE FOR THE PARTICULAR CALENDAR DAY.
THE COMPLEX STORM SYSTEM ITSELF WILL FEATURE A WAVY FRONTAL BOUNDARY
THAT WILL EVENTUALLY INCLUDE A DEEPENING SFC LOW. THE BURGEONING LOW
WILL RIDE ALONG THE FRONT AND LIFT FROM ABOUT WEST VIRGINIA LATE
TONIGHT TO OUR FINGER LAKES ON TUESDAY. A POTENT SHORTWAVE DIVING
INTO THE BASE OF A DIGGING H5 TROUGH OVER THE UPPER MISSISSIPPI
VALLEY WILL ENERGIZE THIS SFC WAVE...WHILE A H25 JET OF 140 KTS OVER
THE UPPER GREAT LAKES WILL PLACE OUR FORECAST AREA UNDER THE
INFLUENCE OF THE JET ENTRANCE REGION. THE COMBINATION OF THE LIFT
FROM THE RR QUAD OF THE H25 JET...THE STRONG LOW LEVEL JET AND
STEADY HGT FALLS WILL PRODUCE DEEP ASCENT FOR THE MOISTURE RICH
AIRMASS. PWAT VALUES WILL INCREASE TO MORE THAN 1.5" FOR MOST SITES.
BREAKING THIS DOWN INTO A FORECAST FOR TONIGHT...RAIN SHOULD
APPROACH THE NEW YORK PENNSYLVANIA LINE AROUND MIDNIGHT...THEN
SPREAD NORTH-NORTHEAST DURING THE REMAINING OVERNIGHT HOURS. THE
RAIN SHOULD REACH THE THOUSANDS ISLAND REGION BY ABOUT DAYBREAK.
BECAUSE OF THE STRONG SOUTHERLY FLOW ALOFT...TEMPS SHOULD REMAIN
WELL ABOVE SEASONAL VALUES TONIGHT WITH LOWS ONLY FORECAST TO DROP
TO WITHIN A COUPLE DEGREES OF 60. NEAR LAKE ERIE AND OVER PARTS OF
THE IAG FRONTIER...LOWS MAY BE CLOSER TO 65. AGAIN...THESE VALUES
WILL BE 10 OR MORE DEG F ABOVE NORMAL.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
VERY ACTIVE WEATHER WILL KICK OFF THIS PERIOD AS A SHARP UPPER LEVEL
TROUGH SLIDES EAST ACROSS THE GREAT LAKES REGION. AT THE SURFACE...
AN ASSOCIATED COMPLEX SURFACE LOW OVER OHIO AND SOUTHERN ONTARIO
TUESDAY MORNING WILL LIFT NORTHEAST INTO QUEBEC BY TUESDAY
EVENING...BEFORE RAPIDLY EJECTING NORTHWARD INTO LABRADOR BY
WEDNESDAY MORNING.
AS HAS BEEN PREVIOUSLY DETAILED IN THIS SPACE...THIS SYSTEM WILL BE
ACCOMPANIED BY A RICH SUPPLY OF GULF MOISTURE...WITH PRECIPITABLE
WATER VALUES RISING TO BETWEEN 1.5 AND 2 INCHES COURTESY OF THE DEEP
SOUTHWESTERLY SYNOPTIC-SCALE FLOW PRECEDING THE LOW. PLENTY OF
FORCING MECHANISMS WILL ALSO BE IN PLACE TO STRONGLY LIFT THIS
MOISTURE...INCLUDING STRONG HEIGHT FALLS AND WARM AIR ADVECTION
ALOFT...EXCELLENT LOW LEVEL CONVERGENCE IN THE VICINITY OF THE
SURFACE WAVE AND AT THE NOSE OF A DEVELOPING 70-80 KT LOW LEVEL
JET...AND STRONG UPPER LEVEL JET DYNAMICS SUPPLIED BY THE RIGHT REAR
QUAD OF A 120+ KT UPPER LEVEL JET STREAK. IT SHOULD GO WITHOUT
SAYING THAT ALL OF THIS MOISTURE AND LIFT WILL ADD UP TO A NEAR
CERTAINTY OF RAINFALL ON TUESDAY...SOME OF WHICH COULD BE HEAVY AT
TIMES. IN ADDITION...SOME WEAK ELEVATED INSTABILITY WILL ALSO BE
PRESENT ALOFT...AND THIS WILL ALSO ALLOW FOR THE POSSIBILITY OF SOME
ISOLATED EMBEDDED THUNDERSTORMS...ESPECIALLY GIVEN THE VERY STRONG
AND DYNAMIC NATURE OF THIS SYSTEM.
IN TERMS OF POTENTIAL RAINFALL AMOUNTS...THE NAM/GFS/GEM/ECMWF HAVE
ALL COME INTO BETTER AGREEMENT ON A SOMEWHAT MORE EASTERLY TRACK TO
THE SURFACE WAVE COMPARED TO 24 HOURS AGO...WITH THE MODEL CONSENSUS
THUS SUPERIMPOSING THE BEST OVERALL LIFT AND RICHEST MOISTURE...AND
CONSEQUENTLY THE GREATEST QPF...ACROSS OUR EASTERN FINGER LAKES AND
NORTH COUNTRY ZONES. IN THIS SPECIFIC REGION...A BLEND OF THE ABOVE
GUIDANCE PACKAGES SUGGEST THAT RAINFALL AMOUNTS OF 1 TO 1.5 INCHES
APPEAR POSSIBLE...WITH LOCALIZED AMOUNTS UP TO 2 INCHES NOT OUT OF
THE QUESTION. MEANWHILE FURTHER TO THE WEST...SOMEWHAT LESSER
RAINFALL AMOUNTS OF A HALF INCH TO AN INCH NOW APPEAR MORE LIKELY.
GIVEN THE VERY DRY ANTECEDENT CONDITIONS...THESE RAINFALL AMOUNTS
WILL BE UNLIKELY TO CAUSE ANY REAL FLOODING CONCERNS ACROSS LARGE
AREAS OR ALONG OUR LARGER CREEKS AND RIVERS...WITH ANY ISSUES MORE
THAN LIKELY REMAINING CONFINED TO LOCALIZED AREAS ALONG SMALLER
STREAMS AND LOW LYING/OTHER AREAS OF POOR DRAINAGE ACROSS OUR
EASTERN ZONES.
WITH ALL OF THE ABOVE IN MIND...HAVE ELECTED TO CONFINE ANY AREAS OF
POTENTIALLY HEAVY RAIN ON TUESDAY TO AREAS FROM THE GENESEE VALLEY
EASTWARD IN THE GRIDS AND WORDED FORECAST...AND WILL ALSO PULL BACK
SOMEWHAT ON THE HEAVY RAIN POTENTIAL IN THE HWO...AGAIN FOCUSING
THIS MORE ON OUR EASTERN ZONES WHERE THE HEAVIER RAINFALL IS MORE
LIKELY.
IN TERMS OF THE TIMING OF THE STEADIEST RAIN...THE ABOVE MODEL
CONSENSUS SUPPORTS A SOMEWHAT FASTER OVERALL TIMING COMPARED TO WHAT
WAS SEEN YESTERDAY...WITH THE STEADIEST AND MOST WIDESPREAD RAIN NOW
APPEARING AS IF IT WILL FALL BETWEEN MID TUESDAY MORNING AND MID
TUESDAY AFTERNOON. AFTER THAT TIME...THE STEADIEST RAINS WILL
QUICKLY TAPER OFF FROM WEST TO EAST BETWEEN LATE TUESDAY AFTERNOON
AND TUESDAY EVENING WITH THE PASSAGE OF THE TRAILING COLD FRONT...
WITH THE BACK EDGE OF THIS NOW APPEARING LIKELY TO EXIT OUR EASTERN
ZONES BETWEEN 03Z AND 06Z WEDNESDAY.
IN THE WAKE OF THE TRAILING COLD FRONT...A WEST-NORTHWESTERLY FLOW
OF MUCH COOLER AIR WILL FLOOD ACROSS THE REGION LATER TUESDAY AND
TUESDAY NIGHT...WITH 850 MB TEMPS PLUNGING TO BETWEEN 0C AND +3C BY
WEDNESDAY MORNING...THEN REMAINING AT THESE LEVELS RIGHT THROUGH
WEDNESDAY. WITH LAKE SURFACE TEMPS STILL RUNNING AROUND 21C...THIS
WILL BE PLENTY COLD ENOUGH TO SET OFF A LAKE RESPONSE...HOWEVER
MOISTURE WILL ONCE AGAIN BE A BIG LIMITING FACTOR THANKS TO
PLENTIFUL DRY AIR AND SUBSIDENCE ADVECTING IN BEHIND THE DEPARTING
LOW/COLD FRONT. WITH THE BULK OF ANY MOISTURE CONFINED TO 5-6 KFT OR
BELOW...WILL ONLY INDICATE SOME LINGERING LOWER-END CHANCE POPS
EAST-SOUTHEAST OF THE LAKES TUESDAY NIGHT...WITH ANY SCATTERED LAKE
EFFECT RAIN SHOWERS THEN FALLING APART ALTOGETHER ON WEDNESDAY WITH
DIURNAL INFLUENCES...AND AS HIGH PRESSURE BUILDS DIRECTLY OVERHEAD
ALONG WITH FURTHER DRYING AND INCREASING SUBSIDENCE. AFTER
THAT...DRY AND QUIET WEATHER IS EXPECTED TO CONTINUE THROUGH
WEDNESDAY NIGHT WITH THE AXIS OF THE AFOREMENTIONED SURFACE RIDGE
REMAINING PARKED DIRECTLY OVERHEAD.
WITH REGARD TO TEMPERATURES...FOLLOWING HIGHS IN THE MID 60S TO
LOWER 70S ON TUESDAY...EXPECT A SHARP COOLDOWN FOR THE REMAINDER
OF THE PERIOD GIVEN THE STRONG COLD AIR ADVECTION PATTERN BEHIND
THE DEPARTING LOW. EXPECT LOWS TO FALL BACK TO THE MID TO UPPER
40S TUESDAY NIGHT...WITH DAYTIME HIGHS ON WEDNESDAY THEN BARELY
REACHING 60 OR SO ACROSS THE LOWER ELEVATIONS...AND LIKELY NOT
MAKING IT OUT OF THE UPPER 50S ACROSS THE HIGHER TERRAIN. EVEN
COOLER READINGS IN THE LOWER TO MID 40S WILL THEN FOLLOW FOR
WEDNESDAY NIGHT...WITH UPPER 30S FOUND ACROSS INTERIOR PORTIONS OF
THE SOUTHERN TIER AND NORTH COUNTRY.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE FIRST HALF OF THE EXTENDED PERIOD WILL BE CHARACTERIZED BY A
LINGERING BROAD/FLAT TROUGH OVER EASTERN NORTH AMERICA RELOADING TO
OUR WEST...AS ANOTHER STRONG SHORTWAVE TROUGH PLUNGES SOUTHEASTWARD
ACROSS THE NORTHERN PLAINS AND WESTERN GREAT LAKES. OUT AHEAD OF
THIS SHORTWAVE...THE PREVAILING SYNOPTIC-SCALE FLOW WILL AGAIN TURN
SOUTHWESTERLY...AND THIS WILL HELP TO TRANSPORT MUCH WARMER AIR BACK
INTO OUR REGION FOR A COUPLE OF DAYS. A BLEND OF THE 00Z GFS AND
ECMWF SUGGESTS 850 MB TEMPS RECOVERING TO BETWEEN +5C AND +8C
THURSDAY AND TO AROUND +11C/+12C FRIDAY...WHICH SHOULD BE ENOUGH TO
BOOST HIGH TEMPS BACK INTO THE 65-70 DEGREE RANGE ON THURSDAY...AND
AT LEAST THE LOWER TO MID 70S ON FRIDAY. THUS...WEDNESDAY`S SHARP
COOLDOWN WILL BE VERY BRIEF...WITH TEMPERATURES RECOVERING TO A BIT
ABOVE NORMAL LEVELS BY THE END OF THE WORK WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE GFS AND ECMWF ARE NOW IN
BETTER AGREEMENT THAT THE VAST MAJORITY OF THE THURSDAY-FRIDAY TIME
FRAME SHOULD REMAIN DRY. BOTH MODELS WEAKEN AN INITIAL LEAD COLD
FRONT AS IT TRIES TO PRESS TOWARD OUR AREA ON THURSDAY...WITH THIS
FEATURE EVENTUALLY FALLING APART OVER SOUTHERN ONTARIO LATE THURSDAY
AND THURSDAY NIGHT. BOTH PACKAGES ALSO ARE NOW IN BETTER AGREEMENT
ON THE EVOLUTION OF A SUBSEQUENT SURFACE WAVE AND ASSOCIATED
STRONGER COLD FRONT...WITH THIS LATTER FEATURE ONLY APPROACHING
FAR WESTERN NEW YORK BY LATE FRIDAY AFTERNOON/FRIDAY EVENING. WITH
THE ABOVE IN MIND...HAVE KEPT PRECIP CHANCES FOR BOTH DAYS LARGELY
CONFINED TO SLIGHT CHANCE OR LESS...WITH ONLY SOME LOW CHANCE POPS
INDICATED ACROSS FAR WESTERN NEW YORK LATER FRIDAY AFTERNOON.
AFTER THAT...BOTH GUIDANCE PACKAGES DIG THE LARGE-SCALE UPPER TROUGH
DEEPER INTO THE CENTRAL AND EASTERN GREAT LAKES NEXT WEEKEND...WITH
THE AFOREMENTIONED SECOND COLD FRONT SLOWLY PUSHING ACROSS THE AREA
BETWEEN FRIDAY NIGHT AND SATURDAY...FOLLOWED BY A SECONDARY AND
WEAKER AREA OF LOW PRESSURE PASSING BY TO OUR NORTH ON SUNDAY. AT
THIS DISTANT JUNCTURE...THIS EVOLUTION IN THE PATTERN WILL SUPPORT
SOME BROADBRUSH LOWER-END SHOWER CHANCES BOTH DAYS...ALONG WITH A
TREND TOWARD PROGRESSIVELY COOLER TEMPERATURES AS THE COLD POOL
ASSOCIATED WITH THE UPPER LOW OVERSPREADS OUR REGION.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
HIGH PRESSURE CENTERED ALONG THE MID ATLANTIC COAST WILL KEEP FAIR
VFR WEATHER IN PLACE THROUGH THE FIRST HALF OF TONIGHT.
LATER TONIGHT AND TUESDAY...MOISTURE TRACKING NORTH FROM THE
TENNESSEE VALLEY WILL INTERACT WITH A COLD FRONT MOVING EAST FROM THE
CENTRAL GREAT LAKES. AS THIS RAIN OVERSPREADS THE AREA...MVFR
CONDITIONS WILL DEVELOP...WITH IFR CONDITIONS LIKELY ACROSS THE
SOUTHERN TIER. AFTER THE COLD FRONT CROSSES THE WESTERN TAF SITES
DURING THE AFTERNOON...EXPECT IFR CONDITIONS TO BECOME MORE
WIDESPREAD.
SOME LOW LEVEL WIND SHEAR HAS BEEN ADDED TO THE TAF SITES LATE
TONIGHT AND TUESDAY MORNING. AS A POTENT LOW LEVEL JET PUSHES EAST
ACROSS WESTERN AND CENTRAL NEW YORK. THE BEST CHANCES FOR LLWS WILL
BE FROM KROC TO KART.
OUTLOOK...
TUESDAY NIGHT...MVFR/IFR IMPROVING TO MVFR/VFR WITH -RA TAPERING OFF
FROM WEST TO EAST.
WEDNESDAY...IMPROVING TO VFR.
THURSDAY AND FRIDAY...MAINLY VFR.
SATURDAY...MAINLY VFR WITH CHANCE -SHRA.
&&
.MARINE...
WHILE HIGH PRESSURE ANCHORED OFF THE MIDDLE ATLANTIC COAST SHOULD
KEEP CONDITIONS BELOW SMALL CRAFT ADVISORY CRITERIA TODAY...WATERS
WILL BE QUITE CHOPPY ACROSS THE EASTERN PART OF LAKE ONTARIO THIS
MORNING AND THEN OVER PARTS OF LAKE ERIE DURING THE MIDDAY AND EARLY
AFTERNOON. IN THOSE AREAS...MODERATE SOUTHERLIES WILL PRODUCE WAVES
OF 2 TO 4 FEET SO THEY WILL HAVE TO BE CLOSELY WATCHED.
WINDS AND WAVES WILL BRIEFLY SUBSIDE ON BOTH LAKES THIS EVENING...
THEN A COMPLEX STORM SYSTEM WILL APPROACH THE LOWER GREAT LAKES
DURING THE OVERNIGHT. WINDS AHEAD OF THIS STORM SYSTEM WILL FRESHEN
OVER EASTERN LAKE ONTARIO LATER TONIGHT...POSSIBLY PRODUCING SCA
CONDITIONS BY DAYBREAK TUESDAY.
STRONGER WINDS ARE EXPECTED IN THE WAKE OF THE STORM SYSTEM TUESDAY
AFTERNOON AND NIGHT WITH FRESH WEST TO NORTHWEST BREEZES PRODUCING
SCA CONDITIONS ACROSS MUCH OF LAKE ONTARIO AND POSSIBLY FOR A SHORT
TIME...ON LAKE ERIE.
HIGH PRESSURE WILL MOVE IN ON WEDNESDAY TO PROMOTE WEAKER WINDS AND
LOWER WAVES.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RSH
NEAR TERM...RSH/TJP
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...TJP
MARINE...RSH
AREA FORECAST DISCUSSION
NWS BUFFALO NY
946 AM EDT MON SEP 17 2012
.SYNOPSIS...
HIGH PRESSURE OFF THE MID ATLANTIC COAST WILL SUPPLY OUR REGION WITH
ONE MORE BEAUTIFUL DAY AS TEMPERATURES WILL SOAR WELL ABOVE NORMAL.
CONDITIONS WILL THEN DETERIORATE TONIGHT AS A COMPLEX STORM SYSTEM
WILL APPROACH FROM THE OHIO VALLEY. THE MOISTURE RICH SYSTEM WILL
SPREAD A SOAKING RAIN ACROSS OUR REGION LATE TONIGHT AND TUESDAY...
WITH SOME SITES PICKING UP OVER AN INCH OF RAIN. HIGH PRESSURE WILL
BRING US A CRISP FALL LIKE DAY FOR WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
PATCHY FOG/STRATUS LINGERING OVER THE SOUTHERN TIER WILL DISSIPATE
BY 11Z. OTHERWISE...MORE IDEAL LATE SUMMER WEATHER IS ON TAP FOR
THE REST OF THE DAY AS HIGH PRESSURE ANCHORED OFF THE MIDDLE
ATLANTIC COAST REMAINS IN CONTROL. SUBSIDENCE...COUPLED WITH A
FAIRLY DRY AIRMASS...WILL RESULT IN MOSTLY SUNNY SKIES...ALTHOUGH
THERE WILL BE SOME INCREASE IN HIGH LEVEL CLOUDS LATER IN THE
AFTERNOON. THE SOUTHERLY FLOW BETWEEN THE SURFACE HIGH AND THE
MIDWEST COLD FRONT WILL ALLOW TEMPERATURES TO WARM WELL INTO THE
70S...AND POSSIBLY 80 DEGREES IN SOME OF THE WARMER VALLEYS.
THESE READINGS WILL BE AT LEAST 10 DEG ABOVE NORMAL.
CLOUDS WILL THEN INCREASE AND THICKEN ACROSS OUR AREA TONIGHT AS A
VERY ENERGETIC...COMPLEX STORM SYSTEM APPROACHES FROM THE OHIO VALLEY.
RICH GULF MOISTURE POOLING OVER THE SOUTHERN STATES AHEAD OF THE
DEVELOPING STORM SYSTEM WILL BE WHISKED NORTHWARDS WITHIN H85-70
WINDS OF 70-80 KTS. THE CORE OF THESE WINDS WILL BE SOUTH OF OUR
REGION TONIGHT...BUT ARE FORECAST TO MOVE OVER EASTERN NEW YORK ON
TUESDAY. THESE EXTREMELY ANOMALOUS WINDS WILL BE AS MUCH AS 5
STANDARD DEVIATIONS FROM NORMAL IN THEIR STRENGTH...WHICH EQUATE TO
AN EVENT THAT HAS LESS THAN ONE HALF OF A PERCENT CHANCE OF
OCCURRENCE FOR THE PARTICULAR CALENDAR DAY.
THE COMPLEX STORM SYSTEM ITSELF WILL FEATURE A WAVY FRONTAL BOUNDARY
THAT WILL EVENTUALLY INCLUDE A DEEPENING SFC LOW. THE BURGEONING LOW
WILL RIDE ALONG THE FRONT AND LIFT FROM ABOUT WEST VIRGINIA LATE
TONIGHT TO OUR FINGER LAKES ON TUESDAY. A POTENT SHORTWAVE DIVING
INTO THE BASE OF A DIGGING H5 TROUGH OVER THE UPPER MISSISSIPPI
VALLEY WILL ENERGIZE THIS SFC WAVE...WHILE A H25 JET OF 140 KTS OVER
THE UPPER GREAT LAKES WILL PLACE OUR FORECAST AREA UNDER THE
INFLUENCE OF THE JET ENTRANCE REGION. THE COMBINATION OF THE LIFT
FROM THE RR QUAD OF THE H25 JET...THE STRONG LOW LEVEL JET AND
STEADY HGT FALLS WILL PRODUCE DEEP ASCENT FOR THE MOISTURE RICH
AIRMASS. PWAT VALUES WILL INCREASE TO MORE THAN 1.5" FOR MOST SITES.
BREAKING THIS DOWN INTO A FORECAST FOR TONIGHT...RAIN SHOULD
APPROACH THE NEW YORK PENNSYLVANIA LINE AROUND MIDNIGHT...THEN
SPREAD NORTH-NORTHEAST DURING THE REMAINING OVERNIGHT HOURS. THE
RAIN SHOULD REACH THE THOUSANDS ISLAND REGION BY ABOUT DAYBREAK.
BECAUSE OF THE STRONG SOUTHERLY FLOW ALOFT...TEMPS SHOULD REMAIN
WELL ABOVE SEASONAL VALUES TONIGHT WITH LOWS ONLY FORECAST TO DROP
TO WITHIN A COUPLE DEGREES OF 60. NEAR LAKE ERIE AND OVER PARTS OF
THE IAG FRONTIER...LOWS MAY BE CLOSER TO 65. AGAIN...THESE VALUES
WILL BE 10 OR MORE DEG F ABOVE NORMAL.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
VERY ACTIVE WEATHER WILL KICK OFF THIS PERIOD AS A SHARP UPPER LEVEL
TROUGH SLIDES EAST ACROSS THE GREAT LAKES REGION. AT THE SURFACE...
AN ASSOCIATED COMPLEX SURFACE LOW OVER OHIO AND SOUTHERN ONTARIO
TUESDAY MORNING WILL LIFT NORTHEAST INTO QUEBEC BY TUESDAY
EVENING...BEFORE RAPIDLY EJECTING NORTHWARD INTO LABRADOR BY
WEDNESDAY MORNING.
AS HAS BEEN PREVIOUSLY DETAILED IN THIS SPACE...THIS SYSTEM WILL BE
ACCOMPANIED BY A RICH SUPPLY OF GULF MOISTURE...WITH PRECIPITABLE
WATER VALUES RISING TO BETWEEN 1.5 AND 2 INCHES COURTESY OF THE DEEP
SOUTHWESTERLY SYNOPTIC-SCALE FLOW PRECEDING THE LOW. PLENTY OF
FORCING MECHANISMS WILL ALSO BE IN PLACE TO STRONGLY LIFT THIS
MOISTURE...INCLUDING STRONG HEIGHT FALLS AND WARM AIR ADVECTION
ALOFT...EXCELLENT LOW LEVEL CONVERGENCE IN THE VICINITY OF THE
SURFACE WAVE AND AT THE NOSE OF A DEVELOPING 70-80 KT LOW LEVEL
JET...AND STRONG UPPER LEVEL JET DYNAMICS SUPPLIED BY THE RIGHT REAR
QUAD OF A 120+ KT UPPER LEVEL JET STREAK. IT SHOULD GO WITHOUT
SAYING THAT ALL OF THIS MOISTURE AND LIFT WILL ADD UP TO A NEAR
CERTAINTY OF RAINFALL ON TUESDAY...SOME OF WHICH COULD BE HEAVY AT
TIMES. IN ADDITION...SOME WEAK ELEVATED INSTABILITY WILL ALSO BE
PRESENT ALOFT...AND THIS WILL ALSO ALLOW FOR THE POSSIBILITY OF SOME
ISOLATED EMBEDDED THUNDERSTORMS...ESPECIALLY GIVEN THE VERY STRONG
AND DYNAMIC NATURE OF THIS SYSTEM.
IN TERMS OF POTENTIAL RAINFALL AMOUNTS...THE NAM/GFS/GEM/ECMWF HAVE
ALL COME INTO BETTER AGREEMENT ON A SOMEWHAT MORE EASTERLY TRACK TO
THE SURFACE WAVE COMPARED TO 24 HOURS AGO...WITH THE MODEL CONSENSUS
THUS SUPERIMPOSING THE BEST OVERALL LIFT AND RICHEST MOISTURE...AND
CONSEQUENTLY THE GREATEST QPF...ACROSS OUR EASTERN FINGER LAKES AND
NORTH COUNTRY ZONES. IN THIS SPECIFIC REGION...A BLEND OF THE ABOVE
GUIDANCE PACKAGES SUGGEST THAT RAINFALL AMOUNTS OF 1 TO 1.5 INCHES
APPEAR POSSIBLE...WITH LOCALIZED AMOUNTS UP TO 2 INCHES NOT OUT OF
THE QUESTION. MEANWHILE FURTHER TO THE WEST...SOMEWHAT LESSER
RAINFALL AMOUNTS OF A HALF INCH TO AN INCH NOW APPEAR MORE LIKELY.
GIVEN THE VERY DRY ANTECEDENT CONDITIONS...THESE RAINFALL AMOUNTS
WILL BE UNLIKELY TO CAUSE ANY REAL FLOODING CONCERNS ACROSS LARGE
AREAS OR ALONG OUR LARGER CREEKS AND RIVERS...WITH ANY ISSUES MORE
THAN LIKELY REMAINING CONFINED TO LOCALIZED AREAS ALONG SMALLER
STREAMS AND LOW LYING/OTHER AREAS OF POOR DRAINAGE ACROSS OUR
EASTERN ZONES.
WITH ALL OF THE ABOVE IN MIND...HAVE ELECTED TO CONFINE ANY AREAS OF
POTENTIALLY HEAVY RAIN ON TUESDAY TO AREAS FROM THE GENESEE VALLEY
EASTWARD IN THE GRIDS AND WORDED FORECAST...AND WILL ALSO PULL BACK
SOMEWHAT ON THE HEAVY RAIN POTENTIAL IN THE HWO...AGAIN FOCUSING
THIS MORE ON OUR EASTERN ZONES WHERE THE HEAVIER RAINFALL IS MORE
LIKELY.
IN TERMS OF THE TIMING OF THE STEADIEST RAIN...THE ABOVE MODEL
CONSENSUS SUPPORTS A SOMEWHAT FASTER OVERALL TIMING COMPARED TO WHAT
WAS SEEN YESTERDAY...WITH THE STEADIEST AND MOST WIDESPREAD RAIN NOW
APPEARING AS IF IT WILL FALL BETWEEN MID TUESDAY MORNING AND MID
TUESDAY AFTERNOON. AFTER THAT TIME...THE STEADIEST RAINS WILL
QUICKLY TAPER OFF FROM WEST TO EAST BETWEEN LATE TUESDAY AFTERNOON
AND TUESDAY EVENING WITH THE PASSAGE OF THE TRAILING COLD FRONT...
WITH THE BACK EDGE OF THIS NOW APPEARING LIKELY TO EXIT OUR EASTERN
ZONES BETWEEN 03Z AND 06Z WEDNESDAY.
IN THE WAKE OF THE TRAILING COLD FRONT...A WEST-NORTHWESTERLY FLOW
OF MUCH COOLER AIR WILL FLOOD ACROSS THE REGION LATER TUESDAY AND
TUESDAY NIGHT...WITH 850 MB TEMPS PLUNGING TO BETWEEN 0C AND +3C BY
WEDNESDAY MORNING...THEN REMAINING AT THESE LEVELS RIGHT THROUGH
WEDNESDAY. WITH LAKE SURFACE TEMPS STILL RUNNING AROUND 21C...THIS
WILL BE PLENTY COLD ENOUGH TO SET OFF A LAKE RESPONSE...HOWEVER
MOISTURE WILL ONCE AGAIN BE A BIG LIMITING FACTOR THANKS TO
PLENTIFUL DRY AIR AND SUBSIDENCE ADVECTING IN BEHIND THE DEPARTING
LOW/COLD FRONT. WITH THE BULK OF ANY MOISTURE CONFINED TO 5-6 KFT OR
BELOW...WILL ONLY INDICATE SOME LINGERING LOWER-END CHANCE POPS
EAST-SOUTHEAST OF THE LAKES TUESDAY NIGHT...WITH ANY SCATTERED LAKE
EFFECT RAIN SHOWERS THEN FALLING APART ALTOGETHER ON WEDNESDAY WITH
DIURNAL INFLUENCES...AND AS HIGH PRESSURE BUILDS DIRECTLY OVERHEAD
ALONG WITH FURTHER DRYING AND INCREASING SUBSIDENCE. AFTER
THAT...DRY AND QUIET WEATHER IS EXPECTED TO CONTINUE THROUGH
WEDNESDAY NIGHT WITH THE AXIS OF THE AFOREMENTIONED SURFACE RIDGE
REMAINING PARKED DIRECTLY OVERHEAD.
WITH REGARD TO TEMPERATURES...FOLLOWING HIGHS IN THE MID 60S TO
LOWER 70S ON TUESDAY...EXPECT A SHARP COOLDOWN FOR THE REMAINDER
OF THE PERIOD GIVEN THE STRONG COLD AIR ADVECTION PATTERN BEHIND
THE DEPARTING LOW. EXPECT LOWS TO FALL BACK TO THE MID TO UPPER
40S TUESDAY NIGHT...WITH DAYTIME HIGHS ON WEDNESDAY THEN BARELY
REACHING 60 OR SO ACROSS THE LOWER ELEVATIONS...AND LIKELY NOT
MAKING IT OUT OF THE UPPER 50S ACROSS THE HIGHER TERRAIN. EVEN
COOLER READINGS IN THE LOWER TO MID 40S WILL THEN FOLLOW FOR
WEDNESDAY NIGHT...WITH UPPER 30S FOUND ACROSS INTERIOR PORTIONS OF
THE SOUTHERN TIER AND NORTH COUNTRY.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE FIRST HALF OF THE EXTENDED PERIOD WILL BE CHARACTERIZED BY A
LINGERING BROAD/FLAT TROUGH OVER EASTERN NORTH AMERICA RELOADING TO
OUR WEST...AS ANOTHER STRONG SHORTWAVE TROUGH PLUNGES SOUTHEASTWARD
ACROSS THE NORTHERN PLAINS AND WESTERN GREAT LAKES. OUT AHEAD OF
THIS SHORTWAVE...THE PREVAILING SYNOPTIC-SCALE FLOW WILL AGAIN TURN
SOUTHWESTERLY...AND THIS WILL HELP TO TRANSPORT MUCH WARMER AIR BACK
INTO OUR REGION FOR A COUPLE OF DAYS. A BLEND OF THE 00Z GFS AND
ECMWF SUGGESTS 850 MB TEMPS RECOVERING TO BETWEEN +5C AND +8C
THURSDAY AND TO AROUND +11C/+12C FRIDAY...WHICH SHOULD BE ENOUGH TO
BOOST HIGH TEMPS BACK INTO THE 65-70 DEGREE RANGE ON THURSDAY...AND
AT LEAST THE LOWER TO MID 70S ON FRIDAY. THUS...WEDNESDAY`S SHARP
COOLDOWN WILL BE VERY BRIEF...WITH TEMPERATURES RECOVERING TO A BIT
ABOVE NORMAL LEVELS BY THE END OF THE WORK WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE GFS AND ECMWF ARE NOW IN
BETTER AGREEMENT THAT THE VAST MAJORITY OF THE THURSDAY-FRIDAY TIME
FRAME SHOULD REMAIN DRY. BOTH MODELS WEAKEN AN INITIAL LEAD COLD
FRONT AS IT TRIES TO PRESS TOWARD OUR AREA ON THURSDAY...WITH THIS
FEATURE EVENTUALLY FALLING APART OVER SOUTHERN ONTARIO LATE THURSDAY
AND THURSDAY NIGHT. BOTH PACKAGES ALSO ARE NOW IN BETTER AGREEMENT
ON THE EVOLUTION OF A SUBSEQUENT SURFACE WAVE AND ASSOCIATED
STRONGER COLD FRONT...WITH THIS LATTER FEATURE ONLY APPROACHING
FAR WESTERN NEW YORK BY LATE FRIDAY AFTERNOON/FRIDAY EVENING. WITH
THE ABOVE IN MIND...HAVE KEPT PRECIP CHANCES FOR BOTH DAYS LARGELY
CONFINED TO SLIGHT CHANCE OR LESS...WITH ONLY SOME LOW CHANCE POPS
INDICATED ACROSS FAR WESTERN NEW YORK LATER FRIDAY AFTERNOON.
AFTER THAT...BOTH GUIDANCE PACKAGES DIG THE LARGE-SCALE UPPER TROUGH
DEEPER INTO THE CENTRAL AND EASTERN GREAT LAKES NEXT WEEKEND...WITH
THE AFOREMENTIONED SECOND COLD FRONT SLOWLY PUSHING ACROSS THE AREA
BETWEEN FRIDAY NIGHT AND SATURDAY...FOLLOWED BY A SECONDARY AND
WEAKER AREA OF LOW PRESSURE PASSING BY TO OUR NORTH ON SUNDAY. AT
THIS DISTANT JUNCTURE...THIS EVOLUTION IN THE PATTERN WILL SUPPORT
SOME BROADBRUSH LOWER-END SHOWER CHANCES BOTH DAYS...ALONG WITH A
TREND TOWARD PROGRESSIVELY COOLER TEMPERATURES AS THE COLD POOL
ASSOCIATED WITH THE UPPER LOW OVERSPREADS OUR REGION.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE CENTERED ALONG THE MID ATLANTIC COAST WILL KEEP FAIR
VFR WEATHER IN PLACE OVER OUR REGION THROUGH THE FIRST HALF OF
TONIGHT...ALTHOUGH THERE COULD BE ANOTHER HOUR OR TWO OF MVFR VSBYS
IN EARLY MORNING FOG FOR SITES SUCH AS KJHW AND KELZ.
DURING THE COURSE OF TONIGHT THOUGH...A COMPLEX STORM SYSTEM WILL
TAKE SHAPE OVER THE UPPER OHIO VALLEY AND SPREAD RAIN AND GENERALLY
DETERIORATING CONDITIONS NORTHWARDS. IFR CONDITIONS WILL DEVELOP
OVER THE WESTERN SOUTHERN TIER WITH MVFR VSBYS/CIGS POSSIBLE FOR THE
REMAINDER OF THE WRN COUNTIES.
SOME LOW LEVEL WIND SHEAR HAS BEEN ADDED TO THE KROC AND KART TAFS
FOR MARGINAL LLWS CONDITIONS LATE TONIGHT.
OUTLOOK...
TUESDAY AND TUESDAY NIGHT...MVFR/IFR WITH RAIN. LLWS.
WEDNESDAY...IMPROVING TO VFR.
THURSDAY AND FRIDAY...MAINLY VFR.
&&
.MARINE...
WHILE HIGH PRESSURE ANCHORED OFF THE MIDDLE ATLANTIC COAST SHOULD
KEEP CONDITIONS BELOW SMALL CRAFT ADVISORY CRITERIA TODAY...WATERS
WILL BE QUITE CHOPPY ACROSS THE EASTERN PART OF LAKE ONTARIO THIS
MORNING AND THEN OVER PARTS OF LAKE ERIE DURING THE MIDDAY AND EARLY
AFTERNOON. IN THOSE AREAS...MODERATE SOUTHERLIES WILL PRODUCE WAVES
OF 2 TO 4 FEET SO THEY WILL HAVE TO BE CLOSELY WATCHED.
WINDS AND WAVES WILL BRIEFLY SUBSIDE ON BOTH LAKES THIS EVENING...
THEN A COMPLEX STORM SYSTEM WILL APPROACH THE LOWER GREAT LAKES
DURING THE OVERNIGHT. WINDS AHEAD OF THIS STORM SYSTEM WILL FRESHEN
OVER EASTERN LAKE ONTARIO LATER TONIGHT...POSSIBLY PRODUCING SCA
CONDITIONS BY DAYBREAK TUESDAY.
STRONGER WINDS ARE EXPECTED IN THE WAKE OF THE STORM SYSTEM TUESDAY
AFTERNOON AND NIGHT WITH FRESH WEST TO NORTHWEST BREEZES PRODUCING
SCA CONDITIONS ACROSS MUCH OF LAKE ONTARIO AND POSSIBLY FOR A SHORT
TIME...ON LAKE ERIE.
HIGH PRESSURE WILL MOVE IN ON WEDNESDAY TO PROMOTE WEAKER WINDS AND
LOWER WAVES.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RSH
NEAR TERM...RSH/TJP
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...RSH
MARINE...RSH
AREA FORECAST DISCUSSION
NWS BUFFALO NY
735 AM EDT MON SEP 17 2012
.SYNOPSIS...
HIGH PRESSURE OFF THE MID ATLANTIC COAST WILL SUPPLY OUR REGION WITH
ONE MORE BEAUTIFUL DAY AS TEMPERATURES WILL SOAR WELL ABOVE NORMAL.
CONDITIONS WILL THEN DETERIORATE TONIGHT AS A COMPLEX STORM SYSTEM
WILL APPROACH FROM THE OHIO VALLEY. THE MOISTURE RICH SYSTEM WILL
SPREAD A SOAKING RAIN ACROSS OUR REGION LATE TONIGHT AND TUESDAY...
WITH SOME SITES PICKING UP OVER AN INCH OF RAIN. HIGH PRESSURE WILL
BRING US A CRISP FALL LIKE DAY FOR WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
IF YOU LIKED THE WEATHER ON SUNDAY...THEN YOU ARE GOING TO LOVE IT
TODAY. HIGH PRESSURE OFF THE MIDDLE ATLANTIC COAST WILL KEEP PLENTY
OF SUBSIDENCE OVER OUR REGION...AND COUPLED WITH A FAIRLY DRY
AIRMASS...WE CAN ANTICIPATE ANOTHER SUN FILLED DAY. THERE WILL BE AN
INCREASE IN HIGH LEVEL CLOUDS LATER IN THE AFTERNOON...BUT NOT
BEFORE H85 TEMPS OF 10C HELP TO BOOST OUR NEAR SFC TEMPS WELL INTO
THE 70S. IN FACT...SOME OF THE WARMER VALLEYS MAY TICKLE 80. THESE
READINGS WILL BE AT LEAST 10 DEG ABOVE NORMAL.
CLOUDS WILL THEN INCREASE AND THICKEN ACROSS OUR FORECAST AREA
DURING THE COURSE OF TONIGHT AS A VERY ENERGETIC...COMPLEX STORM
SYSTEM WILL APPROACH FROM THE OHIO VALLEY. RICH GULF MOISTURE
POOLING OVER THE SOUTHERN STATES AHEAD OF THE DEVELOPING STORM
SYSTEM WILL BE WHISKED NORTHWARDS WITHIN H85-70 WINDS OF 70-80 KTS.
THE CORE OF THESE WINDS WILL BE SOUTH OF OUR REGION TONIGHT...BUT
ARE FORECAST TO MOVE OVER EASTERN NEW YORK ON TUESDAY. THESE
EXTREMELY ANOMALOUS WINDS WILL BE AS MUCH AS 5 STANDARD DEVIATIONS
FROM NORMAL IN THEIR STRENGTH...WHICH EQUATE TO AN EVENT THAT HAS
LESS THAN ONE HALF OF A PERCENT CHANCE OF OCCURRENCE FOR THE
PARTICULAR CALENDAR DAY.
THE COMPLEX STORM SYSTEM ITSELF WILL FEATURE A WAVY FRONTAL BOUNDARY
THAT WILL EVENTUALLY INCLUDE A DEEPENING SFC LOW. THE BURGEONING LOW
WILL RIDE ALONG THE FRONT AND LIFT FROM ABOUT WEST VIRGINIA LATE
TONIGHT TO OUR FINGER LAKES ON TUESDAY. A POTENT SHORTWAVE DIVING
INTO THE BASE OF A DIGGING H5 TROUGH OVER THE UPPER MISSISSIPPI
VALLEY WILL ENERGIZE THIS SFC WAVE...WHILE A H25 JET OF 140 KTS OVER
THE UPPER GREAT LAKES WILL PLACE OUR FORECAST AREA UNDER THE
INFLUENCE OF THE JET ENTRANCE REGION. THE COMBINATION OF THE LIFT
FROM THE RR QUAD OF THE H25 JET...THE STRONG LOW LEVEL JET AND
STEADY HGT FALLS WILL PRODUCE DEEP ASCENT FOR THE MOISTURE RICH
AIRMASS. PWAT VALUES WILL INCREASE TO MORE THAN 1.5" FOR MOST SITES.
BREAKING THIS DOWN INTO A FORECAST FOR TONIGHT...RAIN SHOULD
APPROACH THE NEW YORK PENNSYLVANIA LINE AROUND MIDNIGHT...THEN
SPREAD NORTH-NORTHEAST DURING THE REMAINING OVERNIGHT HOURS. THE
RAIN SHOULD REACH THE THOUSANDS ISLAND REGION BY ABOUT DAYBREAK.
BECAUSE OF THE STRONG SOUTHERLY FLOW ALOFT...TEMPS SHOULD REMAIN
WELL ABOVE SEASONAL VALUES TONIGHT WITH LOWS ONLY FORECAST TO DROP
TO WITHIN A COUPLE DEGREES OF 60. NEAR LAKE ERIE AND OVER PARTS OF
THE IAG FRONTIER...LOWS MAY BE CLOSER TO 65. AGAIN...THESE VALUES
WILL BE 10 OR MORE DEG F ABOVE NORMAL.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
VERY ACTIVE WEATHER WILL KICK OFF THIS PERIOD AS A SHARP UPPER LEVEL
TROUGH SLIDES EAST ACROSS THE GREAT LAKES REGION. AT THE SURFACE...
AN ASSOCIATED COMPLEX SURFACE LOW OVER OHIO AND SOUTHERN ONTARIO
TUESDAY MORNING WILL LIFT NORTHEAST INTO QUEBEC BY TUESDAY
EVENING...BEFORE RAPIDLY EJECTING NORTHWARD INTO LABRADOR BY
WEDNESDAY MORNING.
AS HAS BEEN PREVIOUSLY DETAILED IN THIS SPACE...THIS SYSTEM WILL BE
ACCOMPANIED BY A RICH SUPPLY OF GULF MOISTURE...WITH PRECIPITABLE
WATER VALUES RISING TO BETWEEN 1.5 AND 2 INCHES COURTESY OF THE DEEP
SOUTHWESTERLY SYNOPTIC-SCALE FLOW PRECEDING THE LOW. PLENTY OF
FORCING MECHANISMS WILL ALSO BE IN PLACE TO STRONGLY LIFT THIS
MOISTURE...INCLUDING STRONG HEIGHT FALLS AND WARM AIR ADVECTION
ALOFT...EXCELLENT LOW LEVEL CONVERGENCE IN THE VICINITY OF THE
SURFACE WAVE AND AT THE NOSE OF A DEVELOPING 70-80 KT LOW LEVEL
JET...AND STRONG UPPER LEVEL JET DYNAMICS SUPPLIED BY THE RIGHT REAR
QUAD OF A 120+ KT UPPER LEVEL JET STREAK. IT SHOULD GO WITHOUT
SAYING THAT ALL OF THIS MOISTURE AND LIFT WILL ADD UP TO A NEAR
CERTAINTY OF RAINFALL ON TUESDAY...SOME OF WHICH COULD BE HEAVY AT
TIMES. IN ADDITION...SOME WEAK ELEVATED INSTABILITY WILL ALSO BE
PRESENT ALOFT...AND THIS WILL ALSO ALLOW FOR THE POSSIBILITY OF SOME
ISOLATED EMBEDDED THUNDERSTORMS...ESPECIALLY GIVEN THE VERY STRONG
AND DYNAMIC NATURE OF THIS SYSTEM.
IN TERMS OF POTENTIAL RAINFALL AMOUNTS...THE NAM/GFS/GEM/ECMWF HAVE
ALL COME INTO BETTER AGREEMENT ON A SOMEWHAT MORE EASTERLY TRACK TO
THE SURFACE WAVE COMPARED TO 24 HOURS AGO...WITH THE MODEL CONSENSUS
THUS SUPERIMPOSING THE BEST OVERALL LIFT AND RICHEST MOISTURE...AND
CONSEQUENTLY THE GREATEST QPF...ACROSS OUR EASTERN FINGER LAKES AND
NORTH COUNTRY ZONES. IN THIS SPECIFIC REGION...A BLEND OF THE ABOVE
GUIDANCE PACKAGES SUGGEST THAT RAINFALL AMOUNTS OF 1 TO 1.5 INCHES
APPEAR POSSIBLE...WITH LOCALIZED AMOUNTS UP TO 2 INCHES NOT OUT OF
THE QUESTION. MEANWHILE FURTHER TO THE WEST...SOMEWHAT LESSER
RAINFALL AMOUNTS OF A HALF INCH TO AN INCH NOW APPEAR MORE LIKELY.
GIVEN THE VERY DRY ANTECEDENT CONDITIONS...THESE RAINFALL AMOUNTS
WILL BE UNLIKELY TO CAUSE ANY REAL FLOODING CONCERNS ACROSS LARGE
AREAS OR ALONG OUR LARGER CREEKS AND RIVERS...WITH ANY ISSUES MORE
THAN LIKELY REMAINING CONFINED TO LOCALIZED AREAS ALONG SMALLER
STREAMS AND LOW LYING/OTHER AREAS OF POOR DRAINAGE ACROSS OUR
EASTERN ZONES.
WITH ALL OF THE ABOVE IN MIND...HAVE ELECTED TO CONFINE ANY AREAS OF
POTENTIALLY HEAVY RAIN ON TUESDAY TO AREAS FROM THE GENESEE VALLEY
EASTWARD IN THE GRIDS AND WORDED FORECAST...AND WILL ALSO PULL BACK
SOMEWHAT ON THE HEAVY RAIN POTENTIAL IN THE HWO...AGAIN FOCUSING
THIS MORE ON OUR EASTERN ZONES WHERE THE HEAVIER RAINFALL IS MORE
LIKELY.
IN TERMS OF THE TIMING OF THE STEADIEST RAIN...THE ABOVE MODEL
CONSENSUS SUPPORTS A SOMEWHAT FASTER OVERALL TIMING COMPARED TO WHAT
WAS SEEN YESTERDAY...WITH THE STEADIEST AND MOST WIDESPREAD RAIN NOW
APPEARING AS IF IT WILL FALL BETWEEN MID TUESDAY MORNING AND MID
TUESDAY AFTERNOON. AFTER THAT TIME...THE STEADIEST RAINS WILL
QUICKLY TAPER OFF FROM WEST TO EAST BETWEEN LATE TUESDAY AFTERNOON
AND TUESDAY EVENING WITH THE PASSAGE OF THE TRAILING COLD FRONT...
WITH THE BACK EDGE OF THIS NOW APPEARING LIKELY TO EXIT OUR EASTERN
ZONES BETWEEN 03Z AND 06Z WEDNESDAY.
IN THE WAKE OF THE TRAILING COLD FRONT...A WEST-NORTHWESTERLY FLOW
OF MUCH COOLER AIR WILL FLOOD ACROSS THE REGION LATER TUESDAY AND
TUESDAY NIGHT...WITH 850 MB TEMPS PLUNGING TO BETWEEN 0C AND +3C BY
WEDNESDAY MORNING...THEN REMAINING AT THESE LEVELS RIGHT THROUGH
WEDNESDAY. WITH LAKE SURFACE TEMPS STILL RUNNING AROUND 21C...THIS
WILL BE PLENTY COLD ENOUGH TO SET OFF A LAKE RESPONSE...HOWEVER
MOISTURE WILL ONCE AGAIN BE A BIG LIMITING FACTOR THANKS TO
PLENTIFUL DRY AIR AND SUBSIDENCE ADVECTING IN BEHIND THE DEPARTING
LOW/COLD FRONT. WITH THE BULK OF ANY MOISTURE CONFINED TO 5-6 KFT OR
BELOW...WILL ONLY INDICATE SOME LINGERING LOWER-END CHANCE POPS
EAST-SOUTHEAST OF THE LAKES TUESDAY NIGHT...WITH ANY SCATTERED LAKE
EFFECT RAIN SHOWERS THEN FALLING APART ALTOGETHER ON WEDNESDAY WITH
DIURNAL INFLUENCES...AND AS HIGH PRESSURE BUILDS DIRECTLY OVERHEAD
ALONG WITH FURTHER DRYING AND INCREASING SUBSIDENCE. AFTER
THAT...DRY AND QUIET WEATHER IS EXPECTED TO CONTINUE THROUGH
WEDNESDAY NIGHT WITH THE AXIS OF THE AFOREMENTIONED SURFACE RIDGE
REMAINING PARKED DIRECTLY OVERHEAD.
WITH REGARD TO TEMPERATURES...FOLLOWING HIGHS IN THE MID 60S TO
LOWER 70S ON TUESDAY...EXPECT A SHARP COOLDOWN FOR THE REMAINDER
OF THE PERIOD GIVEN THE STRONG COLD AIR ADVECTION PATTERN BEHIND
THE DEPARTING LOW. EXPECT LOWS TO FALL BACK TO THE MID TO UPPER
40S TUESDAY NIGHT...WITH DAYTIME HIGHS ON WEDNESDAY THEN BARELY
REACHING 60 OR SO ACROSS THE LOWER ELEVATIONS...AND LIKELY NOT
MAKING IT OUT OF THE UPPER 50S ACROSS THE HIGHER TERRAIN. EVEN
COOLER READINGS IN THE LOWER TO MID 40S WILL THEN FOLLOW FOR
WEDNESDAY NIGHT...WITH UPPER 30S FOUND ACROSS INTERIOR PORTIONS OF
THE SOUTHERN TIER AND NORTH COUNTRY.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE FIRST HALF OF THE EXTENDED PERIOD WILL BE CHARACTERIZED BY A
LINGERING BROAD/FLAT TROUGH OVER EASTERN NORTH AMERICA RELOADING TO
OUR WEST...AS ANOTHER STRONG SHORTWAVE TROUGH PLUNGES SOUTHEASTWARD
ACROSS THE NORTHERN PLAINS AND WESTERN GREAT LAKES. OUT AHEAD OF
THIS SHORTWAVE...THE PREVAILING SYNOPTIC-SCALE FLOW WILL AGAIN TURN
SOUTHWESTERLY...AND THIS WILL HELP TO TRANSPORT MUCH WARMER AIR BACK
INTO OUR REGION FOR A COUPLE OF DAYS. A BLEND OF THE 00Z GFS AND
ECMWF SUGGESTS 850 MB TEMPS RECOVERING TO BETWEEN +5C AND +8C
THURSDAY AND TO AROUND +11C/+12C FRIDAY...WHICH SHOULD BE ENOUGH TO
BOOST HIGH TEMPS BACK INTO THE 65-70 DEGREE RANGE ON THURSDAY...AND
AT LEAST THE LOWER TO MID 70S ON FRIDAY. THUS...WEDNESDAY`S SHARP
COOLDOWN WILL BE VERY BRIEF...WITH TEMPERATURES RECOVERING TO A BIT
ABOVE NORMAL LEVELS BY THE END OF THE WORK WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE GFS AND ECMWF ARE NOW IN
BETTER AGREEMENT THAT THE VAST MAJORITY OF THE THURSDAY-FRIDAY TIME
FRAME SHOULD REMAIN DRY. BOTH MODELS WEAKEN AN INITIAL LEAD COLD
FRONT AS IT TRIES TO PRESS TOWARD OUR AREA ON THURSDAY...WITH THIS
FEATURE EVENTUALLY FALLING APART OVER SOUTHERN ONTARIO LATE THURSDAY
AND THURSDAY NIGHT. BOTH PACKAGES ALSO ARE NOW IN BETTER AGREEMENT
ON THE EVOLUTION OF A SUBSEQUENT SURFACE WAVE AND ASSOCIATED
STRONGER COLD FRONT...WITH THIS LATTER FEATURE ONLY APPROACHING
FAR WESTERN NEW YORK BY LATE FRIDAY AFTERNOON/FRIDAY EVENING. WITH
THE ABOVE IN MIND...HAVE KEPT PRECIP CHANCES FOR BOTH DAYS LARGELY
CONFINED TO SLIGHT CHANCE OR LESS...WITH ONLY SOME LOW CHANCE POPS
INDICATED ACROSS FAR WESTERN NEW YORK LATER FRIDAY AFTERNOON.
AFTER THAT...BOTH GUIDANCE PACKAGES DIG THE LARGE-SCALE UPPER TROUGH
DEEPER INTO THE CENTRAL AND EASTERN GREAT LAKES NEXT WEEKEND...WITH
THE AFOREMENTIONED SECOND COLD FRONT SLOWLY PUSHING ACROSS THE AREA
BETWEEN FRIDAY NIGHT AND SATURDAY...FOLLOWED BY A SECONDARY AND
WEAKER AREA OF LOW PRESSURE PASSING BY TO OUR NORTH ON SUNDAY. AT
THIS DISTANT JUNCTURE...THIS EVOLUTION IN THE PATTERN WILL SUPPORT
SOME BROADBRUSH LOWER-END SHOWER CHANCES BOTH DAYS...ALONG WITH A
TREND TOWARD PROGRESSIVELY COOLER TEMPERATURES AS THE COLD POOL
ASSOCIATED WITH THE UPPER LOW OVERSPREADS OUR REGION.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE CENTERED ALONG THE MID ATLANTIC COAST WILL KEEP FAIR
VFR WEATHER IN PLACE OVER OUR REGION THROUGH THE FIRST HALF OF
TONIGHT...ALTHOUGH THERE COULD BE ANOTHER HOUR OR TWO OF MVFR VSBYS
IN EARLY MORNING FOG FOR SITES SUCH AS KJHW AND KELZ.
DURING THE COURSE OF TONIGHT THOUGH...A COMPLEX STORM SYSTEM WILL
TAKE SHAPE OVER THE UPPER OHIO VALLEY AND SPREAD RAIN AND GENERALLY
DETERIORATING CONDITIONS NORTHWARDS. IFR CONDITIONS WILL DEVELOP
OVER THE WESTERN SOUTHERN TIER WITH MVFR VSBYS/CIGS POSSIBLE FOR THE
REMAINDER OF THE WRN COUNTIES.
SOME LOW LEVEL WIND SHEAR HAS BEEN ADDED TO THE KROC AND KART TAFS
FOR MARGINAL LLWS CONDITIONS LATE TONIGHT.
OUTLOOK...
TUESDAY AND TUESDAY NIGHT...MVFR/IFR WITH RAIN. LLWS.
WEDNESDAY...IMPROVING TO VFR.
THURSDAY AND FRIDAY...MAINLY VFR.
&&
.MARINE...
WHILE HIGH PRESSURE ANCHORED OFF THE MIDDLE ATLANTIC COAST SHOULD
KEEP CONDITIONS BELOW SMALL CRAFT ADVISORY CRITERIA TODAY...WATERS
WILL BE QUITE CHOPPY ACROSS THE EASTERN PART OF LAKE ONTARIO THIS
MORNING AND THEN OVER PARTS OF LAKE ERIE DURING THE MIDDAY AND EARLY
AFTERNOON. IN THOSE AREAS...MODERATE SOUTHERLIES WILL PRODUCE WAVES
OF 2 TO 4 FEET SO THEY WILL HAVE TO BE CLOSELY WATCHED.
WINDS AND WAVES WILL BRIEFLY SUBSIDE ON BOTH LAKES THIS EVENING...
THEN A COMPLEX STORM SYSTEM WILL APPROACH THE LOWER GREAT LAKES
DURING THE OVERNIGHT. WINDS AHEAD OF THIS STORM SYSTEM WILL FRESHEN
OVER EASTERN LAKE ONTARIO LATER TONIGHT...POSSIBLY PRODUCING SCA
CONDITIONS BY DAYBREAK TUESDAY.
STRONGER WINDS ARE EXPECTED IN THE WAKE OF THE STORM SYSTEM TUESDAY
AFTERNOON AND NIGHT WITH FRESH WEST TO NORTHWEST BREEZES PRODUCING
SCA CONDITIONS ACROSS MUCH OF LAKE ONTARIO AND POSSIBLY FOR A SHORT
TIME...ON LAKE ERIE.
HIGH PRESSURE WILL MOVE IN ON WEDNESDAY TO PROMOTE WEAKER WINDS AND
LOWER WAVES.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...RSH
MARINE...RSH
AREA FORECAST DISCUSSION
NWS BUFFALO NY
707 AM EDT MON SEP 17 2012
.SYNOPSIS...
HIGH PRESSURE OFF THE MID ATLANTIC COAST WILL SUPPLY OUR REGION WITH
ONE MORE BEAUTIFUL DAY AS TEMPERATURES WILL SOAR WELL ABOVE NORMAL.
CONDITIONS WILL THEN DETERIORATE TONIGHT AS A COMPLEX STORM SYSTEM
WILL APPROACH FROM THE OHIO VALLEY. THE MOISTURE RICH SYSTEM WILL
SPREAD A SOAKING RAIN ACROSS OUR REGION LATE TONIGHT AND TUESDAY...
WITH SOME SITES PICKING UP OVER AN INCH OF RAIN. HIGH PRESSURE WILL
BRING US A CRISP FALL LIKE DAY FOR WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
IF YOU LIKED THE WEATHER ON SUNDAY...THEN YOU ARE GOING TO LOVE IT
TODAY. HIGH PRESSURE OFF THE MIDDLE ATLANTIC COAST WILL KEEP PLENTY
OF SUBSIDENCE OVER OUR REGION...AND COUPLED WITH A FAIRLY DRY
AIRMASS...WE CAN ANTICIPATE ANOTHER SUN FILLED DAY. THERE WILL BE AN
INCREASE IN HIGH LEVEL CLOUDS LATER IN THE AFTERNOON...BUT NOT
BEFORE H85 TEMPS OF 10C HELP TO BOOST OUR NEAR SFC TEMPS WELL INTO
THE 70S. IN FACT...SOME OF THE WARMER VALLEYS MAY TICKLE 80. THESE
READINGS WILL BE AT LEAST 10 DEG ABOVE NORMAL.
CLOUDS WILL THEN INCREASE AND THICKEN ACROSS OUR FORECAST AREA
DURING THE COURSE OF TONIGHT AS A VERY ENERGETIC...COMPLEX STORM
SYSTEM WILL APPROACH FROM THE OHIO VALLEY. RICH GULF MOISTURE
POOLING OVER THE SOUTHERN STATES AHEAD OF THE DEVELOPING STORM
SYSTEM WILL BE WHISKED NORTHWARDS WITHIN H85-70 WINDS OF 70-80 KTS.
THE CORE OF THESE WINDS WILL BE SOUTH OF OUR REGION TONIGHT...BUT
ARE FORECAST TO MOVE OVER EASTERN NEW YORK ON TUESDAY. THESE
EXTREMELY ANOMALOUS WINDS WILL BE AS MUCH AS 5 STANDARD DEVIATIONS
FROM NORMAL IN THEIR STRENGTH...WHICH EQUATE TO AN EVENT THAT HAS
LESS THAN ONE HALF OF A PERCENT CHANCE OF OCCURRENCE FOR THE
PARTICULAR CALENDAR DAY.
THE COMPLEX STORM SYSTEM ITSELF WILL FEATURE A WAVY FRONTAL BOUNDARY
THAT WILL EVENTUALLY INCLUDE A DEEPENING SFC LOW. THE BURGEONING LOW
WILL RIDE ALONG THE FRONT AND LIFT FROM ABOUT WEST VIRGINIA LATE
TONIGHT TO OUR FINGER LAKES ON TUESDAY. A POTENT SHORTWAVE DIVING
INTO THE BASE OF A DIGGING H5 TROUGH OVER THE UPPER MISSISSIPPI
VALLEY WILL ENERGIZE THIS SFC WAVE...WHILE A H25 JET OF 140 KTS OVER
THE UPPER GREAT LAKES WILL PLACE OUR FORECAST AREA UNDER THE
INFLUENCE OF THE JET ENTRANCE REGION. THE COMBINATION OF THE LIFT
FROM THE RR QUAD OF THE H25 JET...THE STRONG LOW LEVEL JET AND
STEADY HGT FALLS WILL PRODUCE DEEP ASCENT FOR THE MOISTURE RICH
AIRMASS. PWAT VALUES WILL INCREASE TO MORE THAN 1.5" FOR MOST SITES.
BREAKING THIS DOWN INTO A FORECAST FOR TONIGHT...RAIN SHOULD
APPROACH THE NEW YORK PENNSYLVANIA LINE AROUND MIDNIGHT...THEN
SPREAD NORTH-NORTHEAST DURING THE REMAINING OVERNIGHT HOURS. THE
RAIN SHOULD REACH THE THOUSANDS ISLAND REGION BY ABOUT DAYBREAK.
BECAUSE OF THE STRONG SOUTHERLY FLOW ALOFT...TEMPS SHOULD REMAIN
WELL ABOVE SEASONAL VALUES TONIGHT WITH LOWS ONLY FORECAST TO DROP
TO WITHIN A COUPLE DEGREES OF 60. NEAR LAKE ERIE AND OVER PARTS OF
THE IAG FRONTIER...LOWS MAY BE CLOSER TO 65. AGAIN...THESE VALUES
WILL BE 10 OR MORE DEG F ABOVE NORMAL.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
VERY ACTIVE WEATHER WILL KICK OFF THIS PERIOD AS A SHARP UPPER LEVEL
TROUGH SLIDES EAST ACROSS THE GREAT LAKES REGION. AT THE SURFACE...
AN ASSOCIATED COMPLEX SURFACE LOW OVER OHIO AND SOUTHERN ONTARIO
TUESDAY MORNING WILL LIFT NORTHEAST INTO QUEBEC BY TUESDAY
EVENING...BEFORE RAPIDLY EJECTING NORTHWARD INTO LABRADOR BY
WEDNESDAY MORNING.
AS HAS BEEN PREVIOUSLY DETAILED IN THIS SPACE...THIS SYSTEM WILL BE
ACCOMPANIED BY A RICH SUPPLY OF GULF MOISTURE...WITH PRECIPITABLE
WATER VALUES RISING TO BETWEEN 1.5 AND 2 INCHES COURTESY OF THE DEEP
SOUTHWESTERLY SYNOPTIC-SCALE FLOW PRECEDING THE LOW. PLENTY OF
FORCING MECHANISMS WILL ALSO BE IN PLACE TO STRONGLY LIFT THIS
MOISTURE...INCLUDING STRONG HEIGHT FALLS AND WARM AIR ADVECTION
ALOFT...EXCELLENT LOW LEVEL CONVERGENCE IN THE VICINITY OF THE
SURFACE WAVE AND AT THE NOSE OF A DEVELOPING 70-80 KT LOW LEVEL
JET...AND STRONG UPPER LEVEL JET DYNAMICS SUPPLIED BY THE RIGHT REAR
QUAD OF A 120+ KT UPPER LEVEL JET STREAK. IT SHOULD GO WITHOUT
SAYING THAT ALL OF THIS MOISTURE AND LIFT WILL ADD UP TO A NEAR
CERTAINTY OF RAINFALL ON TUESDAY...SOME OF WHICH COULD BE HEAVY AT
TIMES. IN ADDITION...SOME WEAK ELEVATED INSTABILITY WILL ALSO BE
PRESENT ALOFT...AND THIS WILL ALSO ALLOW FOR THE POSSIBILITY OF SOME
ISOLATED EMBEDDED THUNDERSTORMS...ESPECIALLY GIVEN THE VERY STRONG
AND DYNAMIC NATURE OF THIS SYSTEM.
IN TERMS OF POTENTIAL RAINFALL AMOUNTS...THE NAM/GFS/GEM/ECMWF HAVE
ALL COME INTO BETTER AGREEMENT ON A SOMEWHAT MORE EASTERLY TRACK TO
THE SURFACE WAVE COMPARED TO 24 HOURS AGO...WITH THE MODEL CONSENSUS
THUS SUPERIMPOSING THE BEST OVERALL LIFT AND RICHEST MOISTURE...AND
CONSEQUENTLY THE GREATEST QPF...ACROSS OUR EASTERN FINGER LAKES AND
NORTH COUNTRY ZONES. IN THIS SPECIFIC REGION...A BLEND OF THE ABOVE
GUIDANCE PACKAGES SUGGEST THAT RAINFALL AMOUNTS OF 1 TO 1.5 INCHES
APPEAR POSSIBLE...WITH LOCALIZED AMOUNTS UP TO 2 INCHES NOT OUT OF
THE QUESTION. MEANWHILE FURTHER TO THE WEST...SOMEWHAT LESSER
RAINFALL AMOUNTS OF A HALF INCH TO AN INCH NOW APPEAR MORE LIKELY.
GIVEN THE VERY DRY ANTECEDENT CONDITIONS...THESE RAINFALL AMOUNTS
WILL BE UNLIKELY TO CAUSE ANY REAL FLOODING CONCERNS ACROSS LARGE
AREAS OR ALONG OUR LARGER CREEKS AND RIVERS...WITH ANY ISSUES MORE
THAN LIKELY REMAINING CONFINED TO LOCALIZED AREAS ALONG SMALLER
STREAMS AND LOW LYING/OTHER AREAS OF POOR DRAINAGE ACROSS OUR
EASTERN ZONES.
WITH ALL OF THE ABOVE IN MIND...HAVE ELECTED TO CONFINE ANY AREAS OF
POTENTIALLY HEAVY RAIN ON TUESDAY TO AREAS FROM THE GENESEE VALLEY
EASTWARD IN THE GRIDS AND WORDED FORECAST...AND WILL ALSO PULL BACK
SOMEWHAT ON THE HEAVY RAIN POTENTIAL IN THE HWO...AGAIN FOCUSING
THIS MORE ON OUR EASTERN ZONES WHERE THE HEAVIER RAINFALL IS MORE
LIKELY.
IN TERMS OF THE TIMING OF THE STEADIEST RAIN...THE ABOVE MODEL
CONSENSUS SUPPORTS A SOMEWHAT FASTER OVERALL TIMING COMPARED TO WHAT
WAS SEEN YESTERDAY...WITH THE STEADIEST AND MOST WIDESPREAD RAIN NOW
APPEARING AS IF IT WILL FALL BETWEEN MID TUESDAY MORNING AND MID
TUESDAY AFTERNOON. AFTER THAT TIME...THE STEADIEST RAINS WILL
QUICKLY TAPER OFF FROM WEST TO EAST BETWEEN LATE TUESDAY AFTERNOON
AND TUESDAY EVENING WITH THE PASSAGE OF THE TRAILING COLD FRONT...
WITH THE BACK EDGE OF THIS NOW APPEARING LIKELY TO EXIT OUR EASTERN
ZONES BETWEEN 03Z AND 06Z WEDNESDAY.
IN THE WAKE OF THE TRAILING COLD FRONT...A WEST-NORTHWESTERLY FLOW
OF MUCH COOLER AIR WILL FLOOD ACROSS THE REGION LATER TUESDAY AND
TUESDAY NIGHT...WITH 850 MB TEMPS PLUNGING TO BETWEEN 0C AND +3C BY
WEDNESDAY MORNING...THEN REMAINING AT THESE LEVELS RIGHT THROUGH
WEDNESDAY. WITH LAKE SURFACE TEMPS STILL RUNNING AROUND 21C...THIS
WILL BE PLENTY COLD ENOUGH TO SET OFF A LAKE RESPONSE...HOWEVER
MOISTURE WILL ONCE AGAIN BE A BIG LIMITING FACTOR THANKS TO
PLENTIFUL DRY AIR AND SUBSIDENCE ADVECTING IN BEHIND THE DEPARTING
LOW/COLD FRONT. WITH THE BULK OF ANY MOISTURE CONFINED TO 5-6 KFT OR
BELOW...WILL ONLY INDICATE SOME LINGERING LOWER-END CHANCE POPS
EAST-SOUTHEAST OF THE LAKES TUESDAY NIGHT...WITH ANY SCATTERED LAKE
EFFECT RAIN SHOWERS THEN FALLING APART ALTOGETHER ON WEDNESDAY WITH
DIURNAL INFLUENCES...AND AS HIGH PRESSURE BUILDS DIRECTLY OVERHEAD
ALONG WITH FURTHER DRYING AND INCREASING SUBSIDENCE. AFTER
THAT...DRY AND QUIET WEATHER IS EXPECTED TO CONTINUE THROUGH
WEDNESDAY NIGHT WITH THE AXIS OF THE AFOREMENTIONED SURFACE RIDGE
REMAINING PARKED DIRECTLY OVERHEAD.
WITH REGARD TO TEMPERATURES...FOLLOWING HIGHS IN THE MID 60S TO
LOWER 70S ON TUESDAY...EXPECT A SHARP COOLDOWN FOR THE REMAINDER
OF THE PERIOD GIVEN THE STRONG COLD AIR ADVECTION PATTERN BEHIND
THE DEPARTING LOW. EXPECT LOWS TO FALL BACK TO THE MID TO UPPER
40S TUESDAY NIGHT...WITH DAYTIME HIGHS ON WEDNESDAY THEN BARELY
REACHING 60 OR SO ACROSS THE LOWER ELEVATIONS...AND LIKELY NOT
MAKING IT OUT OF THE UPPER 50S ACROSS THE HIGHER TERRAIN. EVEN
COOLER READINGS IN THE LOWER TO MID 40S WILL THEN FOLLOW FOR
WEDNESDAY NIGHT...WITH UPPER 30S FOUND ACROSS INTERIOR PORTIONS OF
THE SOUTHERN TIER AND NORTH COUNTRY.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE FIRST HALF OF THE EXTENDED PERIOD WILL BE CHARACTERIZED BY A
LINGERING BROAD/FLAT TROUGH OVER EASTERN NORTH AMERICA RELOADING TO
OUR WEST...AS ANOTHER STRONG SHORTWAVE TROUGH PLUNGES SOUTHEASTWARD
ACROSS THE NORTHERN PLAINS AND WESTERN GREAT LAKES. OUT AHEAD OF
THIS SHORTWAVE...THE PREVAILING SYNOPTIC-SCALE FLOW WILL AGAIN TURN
SOUTHWESTERLY...AND THIS WILL HELP TO TRANSPORT MUCH WARMER AIR BACK
INTO OUR REGION FOR A COUPLE OF DAYS. A BLEND OF THE 00Z GFS AND
ECMWF SUGGESTS 850 MB TEMPS RECOVERING TO BETWEEN +5C AND +8C
THURSDAY AND TO AROUND +11C/+12C FRIDAY...WHICH SHOULD BE ENOUGH TO
BOOST HIGH TEMPS BACK INTO THE 65-70 DEGREE RANGE ON THURSDAY...AND
AT LEAST THE LOWER TO MID 70S ON FRIDAY. THUS...WEDNESDAY`S SHARP
COOLDOWN WILL BE VERY BRIEF...WITH TEMPERATURES RECOVERING TO A BIT
ABOVE NORMAL LEVELS BY THE END OF THE WORK WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE GFS AND ECMWF ARE NOW IN
BETTER AGREEMENT THAT THE VAST MAJORITY OF THE THURSDAY-FRIDAY TIME
FRAME SHOULD REMAIN DRY. BOTH MODELS WEAKEN AN INITIAL LEAD COLD
FRONT AS IT TRIES TO PRESS TOWARD OUR AREA ON THURSDAY...WITH THIS
FEATURE EVENTUALLY FALLING APART OVER SOUTHERN ONTARIO LATE THURSDAY
AND THURSDAY NIGHT. BOTH PACKAGES ALSO ARE NOW IN BETTER AGREEMENT
ON THE EVOLUTION OF A SUBSEQUENT SURFACE WAVE AND ASSOCIATED
STRONGER COLD FRONT...WITH THIS LATTER FEATURE ONLY APPROACHING
FAR WESTERN NEW YORK BY LATE FRIDAY AFTERNOON/FRIDAY EVENING. WITH
THE ABOVE IN MIND...HAVE KEPT PRECIP CHANCES FOR BOTH DAYS LARGELY
CONFINED TO SLIGHT CHANCE OR LESS...WITH ONLY SOME LOW CHANCE POPS
INDICATED ACROSS FAR WESTERN NEW YORK LATER FRIDAY AFTERNOON.
AFTER THAT...BOTH GUIDANCE PACKAGES DIG THE LARGE-SCALE UPPER TROUGH
DEEPER INTO THE CENTRAL AND EASTERN GREAT LAKES NEXT WEEKEND...WITH
THE AFOREMENTIONED SECOND COLD FRONT SLOWLY PUSHING ACROSS THE AREA
BETWEEN FRIDAY NIGHT AND SATURDAY...FOLLOWED BY A SECONDARY AND
WEAKER AREA OF LOW PRESSURE PASSING BY TO OUR NORTH ON SUNDAY. AT
THIS DISTANT JUNCTURE...THIS EVOLUTION IN THE PATTERN WILL SUPPORT
SOME BROADBRUSH LOWER-END SHOWER CHANCES BOTH DAYS...ALONG WITH A
TREND TOWARD PROGRESSIVELY COOLER TEMPERATURES AS THE COLD POOL
ASSOCIATED WITH THE UPPER LOW OVERSPREADS OUR REGION.
&&
.AVIATION /11Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE CENTERED ALONG THE MID ATLANTIC COAST WILL KEEP FAIR
VFR WEATHER IN PLACE OVER OUR REGION THROUGH THE FIRST HALF OF
TONIGHT...ALTHOUGH THERE COULD BE ANOTHER HOUR OR TWO OF MVFR VSBYS
IN EARLY MORNING FOG FOR SITES SUCH AS KJHW AND KELZ.
DURING THE COURSE OF TONIGHT THOUGH...A COMPLEX STORM SYSTEM WILL
TAKE SHAPE OVER THE UPPER OHIO VALLEY AND SPREAD RAIN AND GENERALLY
DETERIORATING CONDITIONS NORTHWARDS. IFR CONDITIONS WILL DEVELOP
OVER THE WESTERN SOUTHERN TIER WITH MVFR VSBYS/CIGS POSSIBLE FOR THE
REMAINDER OF THE WRN COUNTIES.
OUTLOOK...
TUESDAY AND TUESDAY NIGHT...MVFR/IFR WITH RAIN. LLWS.
WEDNESDAY...IMPROVING TO VFR.
THURSDAY AND FRIDAY...MAINLY VFR.
&&
.MARINE...
WHILE HIGH PRESSURE ANCHORED OFF THE MIDDLE ATLANTIC COAST SHOULD
KEEP CONDITIONS BELOW SMALL CRAFT ADVISORY CRITERIA TODAY...WATERS
WILL BE QUITE CHOPPY ACROSS THE EASTERN PART OF LAKE ONTARIO THIS
MORNING AND THEN OVER PARTS OF LAKE ERIE DURING THE MIDDAY AND EARLY
AFTERNOON. IN THOSE AREAS...MODERATE SOUTHERLIES WILL PRODUCE WAVES
OF 2 TO 4 FEET SO THEY WILL HAVE TO BE CLOSELY WATCHED.
WINDS AND WAVES WILL BRIEFLY SUBSIDE ON BOTH LAKES THIS EVENING...
THEN A COMPLEX STORM SYSTEM WILL APPROACH THE LOWER GREAT LAKES
DURING THE OVERNIGHT. WINDS AHEAD OF THIS STORM SYSTEM WILL FRESHEN
OVER EASTERN LAKE ONTARIO LATER TONIGHT...POSSIBLY PRODUCING SCA
CONDITIONS BY DAYBREAK TUESDAY.
STRONGER WINDS ARE EXPECTED IN THE WAKE OF THE STORM SYSTEM TUESDAY
AFTERNOON AND NIGHT WITH FRESH WEST TO NORTHWEST BREEZES PRODUCING
SCA CONDITIONS ACROSS MUCH OF LAKE ONTARIO AND POSSIBLY FOR A SHORT
TIME...ON LAKE ERIE.
HIGH PRESSURE WILL MOVE IN ON WEDNESDAY TO PROMOTE WEAKER WINDS AND
LOWER WAVES.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...RSH
MARINE...RSH
AREA FORECAST DISCUSSION
NWS BUFFALO NY
345 AM EDT MON SEP 17 2012
.SYNOPSIS...
HIGH PRESSURE OFF THE MID ATLANTIC COAST WILL SUPPLY OUR REGION WITH
ONE MORE BEAUTIFUL DAY WITH TEMPERATURES SOARING WELL ABOVE NORMAL.
CONDITIONS WILL DETERIORATE TONIGHT AS A COMPLEX STORM SYSTEM WILL
APPROACH FROM THE OHIO VALLEY. THE MOISTURE RICH SYSTEM WILL SPREAD
A SOAKING RAIN ACROSS OUR REGION LATE TONIGHT AND TUESDAY...WITH
SOME SITES PICKING UP OVER AN INCH OF RAIN. HIGH PRESSURE WILL BRING
US A CRISP FALL LIKE DAY FOR WEDNESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
IF YOU LIKED THE WEATHER ON SUNDAY...THEN YOU ARE GOING TO LOVE IT
TODAY. HIGH PRESSURE OFF THE MIDDLE ATLANTIC COAST WILL KEEP PLENTY
OF SUBSIDENCE OVER OUR REGION...AND COUPLED WITH A FAIRLY DRY
AIRMASS...WE CAN ANTICIPATE ANOTHER SUN FILLED DAY. THERE WILL BE AN
INCREASE IN HIGH LEVEL CLOUDS LATER IN THE AFTERNOON...BUT NOT
BEFORE H85 TEMPS OF 10C HELP TO BOOST OUR NEAR SFC TEMPS WELL INTO
THE 70S. IN FACT...SOME OF THE WARMER VALLEYS MAY TICKLE 80. THESE
READINGS WILL BE AT LEAST 10 DEG ABOVE NORMAL.
CLOUDS WILL THEN INCREASE AND THICKEN ACROSS OUR FORECAST AREA
DURING THE COURSE OF TONIGHT AS A VERY ENERGETIC...COMPLEX STORM
SYSTEM WILL APPROACH FROM THE OHIO VALLEY. RICH GULF MOISTURE
POOLING OVER THE SOUTHERN STATES AHEAD OF THE DEVELOPING STORM
SYSTEM WILL BE WHISKED NORTHWARDS WITHIN H85-70 WINDS OF 70-80 KTS.
THE CORE OF THESE WINDS WILL BE SOUTH OF OUR REGION TONIGHT...BUT
ARE FORECAST TO MOVE OVER EASTERN NEW YORK ON TUESDAY. THESE
EXTREMELY ANOMALOUS WINDS WILL BE AS MUCH AS 5 STANDARD DEVIATIONS
FROM NORMAL IN THEIR STRENGTH...WHICH EQUATE TO AN EVENT THAT HAS
LESS THAN ONE HALF OF A PERCENT CHANCE OF OCCURRENCE FOR THE
PARTICULAR CALENDAR DAY.
THE COMPLEX STORM SYSTEM ITSELF WILL FEATURE A WAVY FRONTAL BOUNDARY
THAT WILL EVENTUALLY INCLUDE A DEEPENING SFC LOW. THE BURGEONING LOW
WILL RIDE ALONG THE FRONT AND LIFT FROM ABOUT WEST VIRGINIA LATE
TONIGHT TO OUR FINGER LAKES ON TUESDAY. A POTENT SHORTWAVE DIVING
INTO THE BASE OF A DIGGING H5 TROUGH OVER THE UPPER MISSISSIPPI
VALLEY WILL ENERGIZE THIS SFC WAVE...WHILE A H25 JET OF 140 KTS OVER
THE UPPER GREAT LAKES WILL PLACE OUR FORECAST AREA UNDER THE
INFLUENCE OF THE JET ENTRANCE REGION. THE COMBINATION OF THE LIFT
FROM THE RR QUAD OF THE H25 JET...THE STRONG LOW LEVEL JET AND
STEADY HGT FALLS WILL PRODUCE DEEP ASCENT FOR THE MOISTURE RICH
AIRMASS. PWAT VALUES WILL INCREASE TO MORE THAN 1.5" FOR MOST SITES.
BREAKING THIS DOWN INTO A FORECAST FOR TONIGHT...RAIN SHOULD
APPROACH THE NEW YORK PENNSYLVANIA LINE AROUND MIDNIGHT...THEN
SPREAD NORTH-NORTHEAST DURING THE REMAINING OVERNIGHT HOURS. THE
RAIN SHOULD REACH THE THOUSANDS ISLAND REGION BY ABOUT DAYBREAK.
BECAUSE OF THE STRONG SOUTHERLY FLOW ALOFT...TEMPS SHOULD REMAIN
WELL ABOVE SEASONAL VALUES TONIGHT WITH LOWS ONLY FORECAST TO DROP
TO WITHIN A COUPLE DEGREES OF 60. NEAR LAKE ERIE AND OVER PARTS OF
THE IAG FRONTIER...LOWS MAY BE CLOSER TO 65. AGAIN...THESE VALUES
WILL BE 10 OR MORE DEG F ABOVE NORMAL.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
VERY ACTIVE WEATHER WILL KICK OFF THIS PERIOD AS A SHARP UPPER LEVEL
TROUGH SLIDES EAST ACROSS THE GREAT LAKES REGION. AT THE SURFACE...
AN ASSOCIATED COMPLEX SURFACE LOW OVER OHIO AND SOUTHERN ONTARIO
TUESDAY MORNING WILL LIFT NORTHEAST INTO QUEBEC BY TUESDAY
EVENING...BEFORE RAPIDLY EJECTING NORTHWARD INTO LABRADOR BY
WEDNESDAY MORNING.
AS HAS BEEN PREVIOUSLY DETAILED IN THIS SPACE...THIS SYSTEM WILL BE
ACCOMPANIED BY A RICH SUPPLY OF GULF MOISTURE...WITH PRECIPITABLE
WATER VALUES RISING TO BETWEEN 1.5 AND 2 INCHES COURTESY OF THE DEEP
SOUTHWESTERLY SYNOPTIC-SCALE FLOW PRECEDING THE LOW. PLENTY OF
FORCING MECHANISMS WILL ALSO BE IN PLACE TO STRONGLY LIFT THIS
MOISTURE...INCLUDING STRONG HEIGHT FALLS AND WARM AIR ADVECTION
ALOFT...EXCELLENT LOW LEVEL CONVERGENCE IN THE VICINITY OF THE
SURFACE WAVE AND AT THE NOSE OF A DEVELOPING 70-80 KT LOW LEVEL
JET...AND STRONG UPPER LEVEL JET DYNAMICS SUPPLIED BY THE RIGHT REAR
QUAD OF A 120+ KT UPPER LEVEL JET STREAK. IT SHOULD GO WITHOUT
SAYING THAT ALL OF THIS MOISTURE AND LIFT WILL ADD UP TO A NEAR
CERTAINTY OF RAINFALL ON TUESDAY...SOME OF WHICH COULD BE HEAVY AT
TIMES. IN ADDITION...SOME WEAK ELEVATED INSTABILITY WILL ALSO BE
PRESENT ALOFT...AND THIS WILL ALSO ALLOW FOR THE POSSIBILITY OF SOME
ISOLATED EMBEDDED THUNDERSTORMS...ESPECIALLY GIVEN THE VERY STRONG
AND DYNAMIC NATURE OF THIS SYSTEM.
IN TERMS OF POTENTIAL RAINFALL AMOUNTS...THE NAM/GFS/GEM/ECMWF HAVE
ALL COME INTO BETTER AGREEMENT ON A SOMEWHAT MORE EASTERLY TRACK TO
THE SURFACE WAVE COMPARED TO 24 HOURS AGO...WITH THE MODEL CONSENSUS
THUS SUPERIMPOSING THE BEST OVERALL LIFT AND RICHEST MOISTURE...AND
CONSEQUENTLY THE GREATEST QPF...ACROSS OUR EASTERN FINGER LAKES AND
NORTH COUNTRY ZONES. IN THIS SPECIFIC REGION...A BLEND OF THE ABOVE
GUIDANCE PACKAGES SUGGEST THAT RAINFALL AMOUNTS OF 1 TO 1.5 INCHES
APPEAR POSSIBLE...WITH LOCALIZED AMOUNTS UP TO 2 INCHES NOT OUT OF
THE QUESTION. MEANWHILE FURTHER TO THE WEST...SOMEWHAT LESSER
RAINFALL AMOUNTS OF A HALF INCH TO AN INCH NOW APPEAR MORE LIKELY.
GIVEN THE VERY DRY ANTECEDENT CONDITIONS...THESE RAINFALL AMOUNTS
WILL BE UNLIKELY TO CAUSE ANY REAL FLOODING CONCERNS ACROSS LARGE
AREAS OR ALONG OUR LARGER CREEKS AND RIVERS...WITH ANY ISSUES MORE
THAN LIKELY REMAINING CONFINED TO LOCALIZED AREAS ALONG SMALLER
STREAMS AND LOW LYING/OTHER AREAS OF POOR DRAINAGE ACROSS OUR
EASTERN ZONES.
WITH ALL OF THE ABOVE IN MIND...HAVE ELECTED TO CONFINE ANY AREAS OF
POTENTIALLY HEAVY RAIN ON TUESDAY TO AREAS FROM THE GENESEE VALLEY
EASTWARD IN THE GRIDS AND WORDED FORECAST...AND WILL ALSO PULL BACK
SOMEWHAT ON THE HEAVY RAIN POTENTIAL IN THE HWO...AGAIN FOCUSING
THIS MORE ON OUR EASTERN ZONES WHERE THE HEAVIER RAINFALL IS MORE
LIKELY.
IN TERMS OF THE TIMING OF THE STEADIEST RAIN...THE ABOVE MODEL
CONSENSUS SUPPORTS A SOMEWHAT FASTER OVERALL TIMING COMPARED TO WHAT
WAS SEEN YESTERDAY...WITH THE STEADIEST AND MOST WIDESPREAD RAIN NOW
APPEARING AS IF IT WILL FALL BETWEEN MID TUESDAY MORNING AND MID
TUESDAY AFTERNOON. AFTER THAT TIME...THE STEADIEST RAINS WILL
QUICKLY TAPER OFF FROM WEST TO EAST BETWEEN LATE TUESDAY AFTERNOON
AND TUESDAY EVENING WITH THE PASSAGE OF THE TRAILING COLD FRONT...
WITH THE BACK EDGE OF THIS NOW APPEARING LIKELY TO EXIT OUR EASTERN
ZONES BETWEEN 03Z AND 06Z WEDNESDAY.
IN THE WAKE OF THE TRAILING COLD FRONT...A WEST-NORTHWESTERLY FLOW
OF MUCH COOLER AIR WILL FLOOD ACROSS THE REGION LATER TUESDAY AND
TUESDAY NIGHT...WITH 850 MB TEMPS PLUNGING TO BETWEEN 0C AND +3C BY
WEDNESDAY MORNING...THEN REMAINING AT THESE LEVELS RIGHT THROUGH
WEDNESDAY. WITH LAKE SURFACE TEMPS STILL RUNNING AROUND 21C...THIS
WILL BE PLENTY COLD ENOUGH TO SET OFF A LAKE RESPONSE...HOWEVER
MOISTURE WILL ONCE AGAIN BE A BIG LIMITING FACTOR THANKS TO
PLENTIFUL DRY AIR AND SUBSIDENCE ADVECTING IN BEHIND THE DEPARTING
LOW/COLD FRONT. WITH THE BULK OF ANY MOISTURE CONFINED TO 5-6 KFT OR
BELOW...WILL ONLY INDICATE SOME LINGERING LOWER-END CHANCE POPS
EAST-SOUTHEAST OF THE LAKES TUESDAY NIGHT...WITH ANY SCATTERED LAKE
EFFECT RAIN SHOWERS THEN FALLING APART ALTOGETHER ON WEDNESDAY WITH
DIURNAL INFLUENCES...AND AS HIGH PRESSURE BUILDS DIRECTLY OVERHEAD
ALONG WITH FURTHER DRYING AND INCREASING SUBSIDENCE. AFTER
THAT...DRY AND QUIET WEATHER IS EXPECTED TO CONTINUE THROUGH
WEDNESDAY NIGHT WITH THE AXIS OF THE AFOREMENTIONED SURFACE RIDGE
REMAINING PARKED DIRECTLY OVERHEAD.
WITH REGARD TO TEMPERATURES...FOLLOWING HIGHS IN THE MID 60S TO
LOWER 70S ON TUESDAY...EXPECT A SHARP COOLDOWN FOR THE REMAINDER
OF THE PERIOD GIVEN THE STRONG COLD AIR ADVECTION PATTERN BEHIND
THE DEPARTING LOW. EXPECT LOWS TO FALL BACK TO THE MID TO UPPER
40S TUESDAY NIGHT...WITH DAYTIME HIGHS ON WEDNESDAY THEN BARELY
REACHING 60 OR SO ACROSS THE LOWER ELEVATIONS...AND LIKELY NOT
MAKING IT OUT OF THE UPPER 50S ACROSS THE HIGHER TERRAIN. EVEN
COOLER READINGS IN THE LOWER TO MID 40S WILL THEN FOLLOW FOR
WEDNESDAY NIGHT...WITH UPPER 30S FOUND ACROSS INTERIOR PORTIONS OF
THE SOUTHERN TIER AND NORTH COUNTRY.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE FIRST HALF OF THE EXTENDED PERIOD WILL BE CHARACTERIZED BY A
LINGERING BROAD/FLAT TROUGH OVER EASTERN NORTH AMERICA RELOADING TO
OUR WEST...AS ANOTHER STRONG SHORTWAVE TROUGH PLUNGES SOUTHEASTWARD
ACROSS THE NORTHERN PLAINS AND WESTERN GREAT LAKES. OUT AHEAD OF
THIS SHORTWAVE...THE PREVAILING SYNOPTIC-SCALE FLOW WILL AGAIN TURN
SOUTHWESTERLY...AND THIS WILL HELP TO TRANSPORT MUCH WARMER AIR BACK
INTO OUR REGION FOR A COUPLE OF DAYS. A BLEND OF THE 00Z GFS AND
ECMWF SUGGESTS 850 MB TEMPS RECOVERING TO BETWEEN +5C AND +8C
THURSDAY AND TO AROUND +11C/+12C FRIDAY...WHICH SHOULD BE ENOUGH TO
BOOST HIGH TEMPS BACK INTO THE 65-70 DEGREE RANGE ON THURSDAY...AND
AT LEAST THE LOWER TO MID 70S ON FRIDAY. THUS...WEDNESDAY`S SHARP
COOLDOWN WILL BE VERY BRIEF...WITH TEMPERATURES RECOVERING TO A BIT
ABOVE NORMAL LEVELS BY THE END OF THE WORK WEEK.
IN TERMS OF PRECIPITATION CHANCES...THE GFS AND ECMWF ARE NOW IN
BETTER AGREEMENT THAT THE VAST MAJORITY OF THE THURSDAY-FRIDAY TIME
FRAME SHOULD REMAIN DRY. BOTH MODELS WEAKEN AN INITIAL LEAD COLD
FRONT AS IT TRIES TO PRESS TOWARD OUR AREA ON THURSDAY...WITH THIS
FEATURE EVENTUALLY FALLING APART OVER SOUTHERN ONTARIO LATE THURSDAY
AND THURSDAY NIGHT. BOTH PACKAGES ALSO ARE NOW IN BETTER AGREEMENT
ON THE EVOLUTION OF A SUBSEQUENT SURFACE WAVE AND ASSOCIATED
STRONGER COLD FRONT...WITH THIS LATTER FEATURE ONLY APPROACHING
FAR WESTERN NEW YORK BY LATE FRIDAY AFTERNOON/FRIDAY EVENING. WITH
THE ABOVE IN MIND...HAVE KEPT PRECIP CHANCES FOR BOTH DAYS LARGELY
CONFINED TO SLIGHT CHANCE OR LESS...WITH ONLY SOME LOW CHANCE POPS
INDICATED ACROSS FAR WESTERN NEW YORK LATER FRIDAY AFTERNOON.
AFTER THAT...BOTH GUIDANCE PACKAGES DIG THE LARGE-SCALE UPPER TROUGH
DEEPER INTO THE CENTRAL AND EASTERN GREAT LAKES NEXT WEEKEND...WITH
THE AFOREMENTIONED SECOND COLD FRONT SLOWLY PUSHING ACROSS THE AREA
BETWEEN FRIDAY NIGHT AND SATURDAY...FOLLOWED BY A SECONDARY AND
WEAKER AREA OF LOW PRESSURE PASSING BY TO OUR NORTH ON SUNDAY. AT
THIS DISTANT JUNCTURE...THIS EVOLUTION IN THE PATTERN WILL SUPPORT
SOME BROADBRUSH LOWER-END SHOWER CHANCES BOTH DAYS...ALONG WITH A
TREND TOWARD PROGRESSIVELY COOLER TEMPERATURES AS THE COLD POOL
ASSOCIATED WITH THE UPPER LOW OVERSPREADS OUR REGION.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE CENTERED ALONG THE MID ATLANTIC COAST WILL KEEP FAIR
VFR WEATHER IN PLACE OVER OUR REGION THROUGH TODAY...ALTHOUGH THERE
COULD BE A FEW HOURS OF MVFR VSBYS IN EARLY MORNING FOG FOR SITES
SUCH AS KJHW AND KELZ.
DURING THE COURSE OF TONIGHT THOUGH...A COMPLEX STORM SYSTEM
WILL DEVELOP OVER THE UPPER OHIO VALLEY AND SPREAD RAIN AND
GENERALLY DETERIORATING CONDITIONS NORTHWARDS. IFR CONDITIONS SHOULD
BE FOUND OVER THE WESTERN SOUTHERN TIER WITH MVFR VSBYS/CIGS
POSSIBLE FOR THE REMAINDER OF THE WRN COUNTIES.
OUTLOOK...
TUESDAY AND TUESDAY NIGHT...MVFR/IFR WITH RAIN. LLWS.
WEDNESDAY...IMPROVING TO VFR.
THURSDAY AND FRIDAY...MAINLY VFR.
&&
.MARINE...
WHILE HIGH PRESSURE ANCHORED OFF THE MIDDLE ATLANTIC COAST SHOULD
KEEP CONDITIONS BELOW SMALL CRAFT ADVISORY CRITERIA TODAY...WATERS
WILL BE QUITE CHOPPY ACROSS THE EASTERN PART OF LAKE ONTARIO THIS
MORNING AND THEN OVER PARTS OF LAKE ERIE DURING THE MIDDAY AND EARLY
AFTERNOON. IN THOSE AREAS...MODERATE SOUTHERLIES WILL PRODUCE WAVES
OF 2 TO 4 FEET SO THEY WILL HAVE TO BE CLOSELY WATCHED.
WINDS AND WAVES WILL BRIEFLY SUBSIDE ON BOTH LAKES THIS EVENING...
THEN A COMPLEX STORM SYSTEM WILL APPROACH THE LOWER GREAT LAKES
DURING THE OVERNIGHT. WINDS AHEAD OF THIS STORM SYSTEM WILL FRESHEN
OVER EASTERN LAKE ONTARIO LATER TONIGHT...POSSIBLY PRODUCING SCA
CONDITIONS BY DAYBREAK TUESDAY.
STRONGER WINDS ARE EXPECTED IN THE WAKE OF THE STORM SYSTEM TUESDAY
AFTERNOON AND NIGHT WITH FRESH WEST TO NORTHWEST BREEZES PRODUCING
SCA CONDITIONS ACROSS MUCH OF LAKE ONTARIO AND POSSIBLY FOR A SHORT
TIME...ON LAKE ERIE.
HIGH PRESSURE WILL MOVE IN ON WEDNESDAY TO PROMOTE WEAKER WINDS AND
LOWER WAVES.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...RSH
MARINE...RSH
AREA FORECAST DISCUSSION
NWS NEWPORT/MOREHEAD CITY NC
403 PM EDT MON SEP 17 2012
.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFFSHORE TONIGHT. A STRONG COLD FRONT WILL
APPROACH THE AREA TUESDAY AND MOVE OFFSHORE WEDNESDAY AFTERNOON. HIGH
PRESSURE WILL BUILD IN BEHIND THE FRONT THURSDAY AND FRIDAY. AN
EVEN STRONGER COLD FRONT WILL MOVE ACROSS THE AREA SATURDAY INTO
SUNDAY.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AS OF 345 PM MONDAY...SCATTERED SHOWERS CONTINUE OVER MOST OF
EASTERN NORTH CAROLINA AWAY FROM THE SOUTHERN COAST IN ASSOCIATION
WITH WEAK BOUNDARY. ALTHOUGH NO LIGHTNING HAS BEEN OBSERVED SO FAR
TODAY...THERE IS SUFFICIENT INSTABILITY FOR A FEW EMBEDDED TSTMS
AND WILL LEAVE IN FORECAST. RAP AND NAM12 INDICATE A BIT OF A
BREAK OF THE PRECIP LATER TONIGHT...BUT NOT CONFIDENT IN THAT
GIVEN THAT COVERAGE HAS ALREADY BEEN HIGHER THAN PREVIOUS FORECAST
BY THOSE MODELS. MINIMUM TEMPERATURES TONIGHT SHOULD BE IN THE
UPPER 60S TO LOWER 70S UNDER MOSTLY CLOUDY SKIES.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/...
AS OF 345 PM MONDAY...TUESDAY LOOKS TO BE A WET DAY AHEAD OF
APPROACHING STRONG COLD FRONT. PRECIPITABLE WATER VALUES SURGE TO
NEARLY 2.5 INCHES BY 18Z AND SHOWERS AND TSTMS BECOME WIDESPREAD.
HAVE HIGH LIKELY TO CATEGORICAL POPS OVER THE WESTERN AREAS BY
LATE MORNING...SPREADING TO THE COAST DURING THE AFTERNOON HOURS.
THE ENTIRE CWA REMAINS IN A SLIGHT RISK OF SEVERE TSTMS FOR
TUESDAY AS WELL. WHILE THERE WILL BE SOME MODERATE INSTABILITY
OVER THE SOUTHERN COUNTIES...ESPECIALLY IF WE GET SOME
INSOLATION...THE BEST SHEAR VALUES WILL MAINLY BE TO OUR NORTH
OVER VIRGINIA AND AREAS FURTHER NORTH. THINK THE BEST CHANCE FOR
SEVERE WOULD BE IN OUR NORTHERN COUNTIES CLOSER TO THE MID/UPPER
LEVEL JET MAXIMUM. WENT A COUPLE OF DEGREES BELOW NUMERICAL
GUIDANCE TEMPERATURES GIVEN EXPECTED CLOUD COVER AND ONGOING
PRECIPITATION EARLY IN THE DAY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
AS OF 330 PM MONDAY...LITTLE CHANGE IN FORECAST REASONING FOR THE
AFTERNOON PACKAGE. A COLD FRONT WILL APPROACH FROM THE W TUE NIGHT
AND SLOWLY MOVE OFFSHORE WED AS UPR TRF DEVELOPS TO THE W. VERY DEEP
MOISTURE AHEAD OF THE FRONT WITH PRECIP WTR VALUES AOA 2 INCHES
THROUGH TUE NIGHT OVER THE AREA. THIS COMBINED WITH DECENT FORCING
WILL LEAD TO GOOD CVRG OF SHRA AND A FEW TSRA. THREAT OF SOME
STRONG/SVR STORMS WITH GUSTY WINDS CONTINUES TUE NIGHT WITH DESCENT
FORCING DESPITE LOSS OF SFC BASED INSTABILITY. VERY WARM TEMPS ALOFT
SHLD LIMIT HAIL THREAT.
WITH THE UPR TRF EXPECTED TO CONT TO THE W THRU THE END OF THE WEEK
THE FRONT WILL ONLY SLOWLY CROSS LATE TUE NIGHT AND WED AND WL
LIKELY LINGER JUST OFF THE CST INTO THU. THIS WILL KEEP CHC OF SHRA
GOING ESPCLY CST WED AND WED NIGHT WITH SLIGHT CHC CST THU. SHLD BE
MAINLY DRY FRI AND SAT AS HIGH PRES CROSSES THEN CONT A SLIGHT POP
SUNDAY ASSOC WITH NEXT FRONT. VERY LITTLE QPF EXPECTED WITH THIS
FRONT WITH LIMITED GULF MOISTURE FEED.
HIGHS MAINLY 70S WED AND THU BEHIND FRONT AS EXPECT PLENTY OF
CLOUDS. WITH MORE SUN EXPECT LOWER 80S AGAIN MOST AREAS FRI INTO THE
WEEKEND. BELOW NORMAL TEMPS AND DRY CONDITIONS EXPECTED EARLY NEXT
WEEK WITH COOL HIGH PRES BUILDING IN BEHIND THE COLD FRONT.
&&
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
SHORT TERM /TONIGHT AND TUESDAY/...
AS OF 4 PM MONDAY...EXPECT CEILINGS TO GRADUALLY LOWER THROUGH THE
EVENING AND REACH MVFR STATUS DURING THE EARLY MORNING HOURS.
SHOWERS AND TSTMS BECOME WIDESPREAD BY MID-MORNING TUESDAY
ACCOMPANIED BY GUSTY SOUTH WINDS. WHILE CEILINGS WILL GENERALLY BE
VFR EXPECT NUMEROUS REDUCTIONS TO MVFR AND PERHAPS BRIEFLY IFR
IN HEAVIER SHOWERS TUESDAY AFTERNOON AND EVENING.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 330 PM MON...NUMEROUS SHRA AND A FEW TSRA WILL CONTINUE
TUE NIGHT WITH PDS OF REDUCED CIGS AND VSBYS LIKELY. PRECIP
WILL GRADUALLY END FROM W TO E WED AND WED NIGHT HOWEVER WITH POST
FRONTAL INVERSION AND PLENTY OF LOW LVL MOISTURE LOW CLOUDS IN
MVFR TO OCNL IFR RANGE WILL PERSIST. LOW LVLS SHLD DRY THU WITH
VFR BECOMING DOMINATE AND THAT SHLD CONT FRI AND SAT.
&&
.MARINE...
SHORT TERM /TONIGHT AND TUESDAY/...
AS OF 4 PM MONDAY...SE/SSE WINDS CONTINUE IN THE 10 TO 15 KNOT
RANGE LATE THIS AFTERNOON WITH 3 TO 4 FOOT SEAS ACCOMPANIED BY A
10 TO 12 SECOND SWELL COMPONENT. AS THE STRONG COLD FRONT
APPROACHES THIS EVENING...SOUTHERLY WINDS SHOULD START TO RAMP UP
AFTER MIDNIGHT AND BE GUSTY AT 20 TO 25 KNOTS ON TUESDAY. HAVE
ADDED THE ALBEMARLE AND PAMLICO SOUNDS TO THE SMALL CRAFT ADVISORY
FROM TUESDAY MORNING THROUGH THE DAY TUESDAY INTO EARLY WEDNESDAY.
SEAS SHOULD BUILD TO AS HIGH AS 7 TO 8 FEET...ESPECIALLY OVER THE
OUTER WATERS BY LATE TONIGHT AND THROUGH TUESDAY. THE ROUGH SEAS
AND HIGHER THAN NORMAL TIDES WILL LEAD TO A MODERATE RIP CURRENT
THREAT ON TUESDAY.
LONG TERM /TUESDAY EVENING THROUGH FRIDAY/...
AS OF 330 PM MON...SCA WILL BE ONGOING TUE EVE WITH SRLY WINDS OF 20
TO 25 KTS. 12Z WAVEWATCH A LITTLE HIGHER WITH SEAS...NOW PEAKING
AROUND 6 TO 8 FEET OUTER WTRS TUE NIGHT. THE GUSTY S/SW WINDS WILL
DIMINISH TOWARD WED MORN AS FRONT REACHES CST WITH SEAS EXPECTED TO
DROP BELOW SCA CRITERIA ALL WATERS AROUND MID DAY WED. DECENT NRLY
FLOW WILL DEVELOP WED AFTN AS FRONT DRIFTS OFFSHORE...FOR NOW HAVE
WINDS AOB 20 KTS BEHIND FRONT WITH SEAS NO HIGHER THAN 5 FEET. N/NE
WINDS WILL CONT THU THROUGH FRI AT MAINLY 10 TO 15 KTS AS HIGH PRES
BUILDS TO THE CST AND FRONT DRIFTS OFFSHORE. SEAS OF 2 TO 4 FEET THU
WILL SUBSIDE A BIT FRI AS WINDS BECOME LIGHT WITH HIGH NEAR THE CST.
WINDS COME AROUND TO S/SWLY SAT AS HIGH PRES WEAKENS AND A COLD
FRONT QUICKLY APPROACHES FROM THE NW. AT THIS TIME MODELS KEEP WINDS
AOB 15 KT WHILE WAVEWATCH BUILDS SEAS TO 3-5 FT.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...BEACH HAZARDS STATEMENT UNTIL 8 PM EDT THIS EVENING FOR NCZ095-
103-104.
MARINE...SMALL CRAFT ADVISORY FROM 5 AM TUESDAY TO 8 AM EDT WEDNESDAY
FOR AMZ130-135-150.
SMALL CRAFT ADVISORY FROM 5 AM TUESDAY TO 2 PM EDT WEDNESDAY
FOR AMZ152-154.
SMALL CRAFT ADVISORY FROM 5 AM TUESDAY TO 11 AM EDT WEDNESDAY
FOR AMZ156-158.
&&
$$
SYNOPSIS...CTC
NEAR TERM...CTC
SHORT TERM...CTC
LONG TERM...SK/RF
AVIATION...CTC/SK/RF
MARINE...CTC/SK/RF
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1000 AM EDT MON SEP 17 2012
.SYNOPSIS...
HIGH PRESSURE WILL SLIP OFFSHORE TODAY...AS A COLD FRONT APPROACHES
FROM THE WEST. THE FRONT WILL BRING SHOWERS AND THUNDERSTORMS TO THE
CAROLINAS TUESDAY...AND SOME STORMS MAY BE SEVERE. THE COLD FRONT
WILL LINGER NEAR THE COAST WEDNESDAY...BEFORE HIGH PRESSURE PUSHES
COOLER AND DRIER WEATHER INTO THE AREA THURSDAY AND FRIDAY. WEAK
HIGH PRESSURE WILL HOLD OVER THE REGION INTO NEXT WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 945 AM MONDAY...A WEAK WEST TO EAST BOUNDARY WAS POSITIONED
ACROSS OUR VERY NORTHERN TIER...AND THIS FEATURE WILL TRANSITION TO
A NORTHWARD LIFTING WARM FRONT THROUGH THE DAY AND TONIGHT. THIS
WILL LEAVE OUR FORECAST AREA IN AN UNSTABLE WARM SECTOR TODAY. THIS
SHOULD ALLOW AN ERUPTION OF ISOLATED TO SCATTERED SHOWERS AND TSTMS
THIS AFTERNOON. GIVEN THAT PLENTY SUNSHINE APPEARS IN THE CARDS FOR
TODAY...BELIEVE THE SEA BREEZE FRONT WILL PLAY A ROLE IN CONVECTIVE
INITIATION AND COULD FOCUS STRONGER STORMS INLAND THROUGH THE AFTN
HOURS. LOSS OF HEATING WILL WEAKEN CONVECTION IN THE EARLY EVENING
AND THE BULK OF ACTIVITY MAY HAVE CLEARED OR CLUSTERED STORMS OVER
OUR FAR INLAND AREAS LATE IN THE AFTERNOON TO EARLY EVENING.
TONIGHT A TAP OF GULF AND ATLANTIC MOISTURE WILL INCREASE PWAT
VALUES ABOVE 2 INCHES WITH INCREASING SOUTHERLY FLOW AHEAD OF AN
ENERGETIC UPPER TROUGH. FAVORABLE LOW-LEVEL HODOGRAPHS OVERNIGHT
MAY LEAD TO A FEW ROTATING TSTMS MOVING ONSHORE...MAINLY FROM
MIDNIGHT THROUGH EARLY TUESDAY MORNING.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...STRONG COLD FRONT STILL PROGGED TO CROSS THE
AREA TUESDAY BRINGING WIDESPREAD SHOWERS/TSTMS...POTENTIALLY WITH
DAMAGING WINDS AND HEAVY RAIN TO THE AREA...IN AN EARLY SEASON
HIGH SHEAR LOW CAPE EVENT.
PHASING OCCURRING AT 500MB TUESDAY BETWEEN SOUTHERN AND NORTHERN
STREAM IMPULSES CREATES A HIGHLY AMPLIFIED TROUGH ACROSS THE EASTERN
CONUS. SURFACE LOW RIDES UP THE APPALACHIANS AND DRIVES A COLD ACROSS
THE CAROLINAS. STRONG LOW LEVEL WINDS...APPROACHING 50 KTS AT
850MB...ADVECT COPIOUS MOISTURE INTO THE COLUMN AND STRONG MID-LEVEL
THETA-E ADVECTION OCCURS AHEAD OF THIS FRONT. SPC HAS PLACED THE
ENTIRE AREA IN A SLIGHT RISK FOR TUESDAY...30% PROBABILITIES ACROSS
THE I-95 COUNTIES...AND THIS SEEMS WARRANTED BASED OFF THE STRONG
LOW LEVEL WIND FIELDS.
DO NOT EXPECT WIDESPREAD SEVERE WINDS TUESDAY...BUT ISOLATED TO
POTENTIALLY SCATTERED DAMAGING WIND GUSTS ARE POSSIBLE. 0-6KM BULK
SHEAR RISES TO AROUND 30 KTS WHICH COULD SUPPORT MULTICELL CLUSTERS
WITH STRONG WINDS IN A UNIDIRECTIONAL SHEAR ENVIRONMENT...AND
FORECAST SBCAPE RISES TO AROUND 1000 J/KG AHEAD OF THE FRONT.
HOWEVER...DCAPE IS MINIMAL...UPPER FORCING LAGS BEHIND THE BEST
SURFACE DYNAMICS...AND FRONT ITSELF WILL CROSS DURING THE NIGHTTIME
HOURS...ALTHOUGH WITH STRONG THETA-E ADVECTION OCCURRING RIGHT UP
UNTIL FROPA...CONVECTION MAY SUSTAIN ITSELF WELL PAST NIGHTFALL.
SO...CANNOT RULE OUT A FEW DAMAGING WIND GUSTS...ESPECIALLY SINCE
SUSTAINED GRADIENT WINDS WILL LIKELY BE AROUND 20 MPH TO BEGIN
WITH...AND IT WILL NOT TAKE AN INCREDIBLY STRONG STORM TO MIX DOWN
THE LLJ WINDS. STILL...DO NOT ANTICIPATE A WIDESPREAD SEVERE WEATHER
EVENT IN THE ILM CWA...SINCE BEST COMBINATION OF FORCING SHOULD BE
DISPLACED NW OF THIS AREA. HEAVY RAIN ON THE OTHER HAND WILL BE THE
MORE SIGNIFICANT THREAT...WITH TORRENTIAL RAINFALL LIKELY IN
CONVECTION.
FRONT CROSSES THE AREA VERY EARLY WEDNESDAY...BUT INDICATIONS ARE
NOW THAT IT WILL HANG BACK NEAR THE COAST AS A SECONDARY LOW
DEVELOPS ACROSS THE SOUTHEAST AND UPPER TROUGHING LAGS BEHIND. THIS
WILL KEEP PRECIP CHANCES THROUGHOUT THE SHORT TERM...ALTHOUGH MUCH
LIGHTER QPF EXPECTED WEDNESDAY...HIGHEST NEAR THE COAST.
FORECAST PROFILES SUGGEST A WEAK WEDGE SCENARIO (RARE FOR THIS EARLY
IN THE SEASON) DEVELOPING WEDNESDAY NIGHT AS HIGH PRESSURE SETTLES
DOWN THE COAST WHILE SW FLOW REMAINS ABOVE 900MB. THIS SUGGESTS SOME
LIGHT RAIN OR EVEN DRIZZLE POTENTIALLY PERSISTING THROUGH THE END OF
THE PERIOD. VERY DRY AIR ABOVE THE WEDGE...PLUS THIS BEING OUT OF
SEASON...MEANS THAT ONLY SCHC POP WILL BE CONTINUED THROUGH THE END
OF THE SHORT TERM BUT CLOUD COVER SHOULD BE PRETTY
SIGNIFICANT...ESPECIALLY NEAR THE COAST.
HIGH TEMPS TUESDAY WILL BE RIGHT AROUND CLIMO...LOW 80S...AS STRONG
WAA IS COUNTERACTED BY CLOUD COVER AND SHOWERS...WHILE NIGHTTIME
MINS WILL BE HELD WELL ABOVE NORMAL...ONLY FALLING TO THE UPPER
60S/LOW 70S. WEDNESDAY WILL BE COOLER BEHIND THE FRONT...AROUND 80
FOR HIGHS AND NEAR 60 FOR LOWS AWAY FROM THE IMMEDIATE COAST.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 300 AM MONDAY...FRONT HOVERING JUST OFFSHORE MAY ALLOW FOR
CONTINUED SHOWERS NEAR THE COAST ON THURSDAY. FORECAST PROFILES DRY
OUT CONSIDERABLY HOWEVER...AND WILL DROP INHERITED CHC TO JUST SCHC
ON THE COAST...SILENT INLAND. BEST CHANCE WILL BE DURING THE EARLY
PART OF THE DAY BEFORE HIGH PRESSURE MORE FIRMLY RIDGES DOWN THE
COAST FORCING THE FRONT FURTHER OFFSHORE. OTHERWISE...THE EXTENDED
FEATURES DRY AND SEASONABLE WEATHER AS HIGH PRESSURE DOMINATES AT
THE SURFACE AND A LARGE UPPER TROUGH PERSISTS OVER THE EASTERN HALF
OF THE COUNTRY. ONLY FEATURE OF INTEREST IS A COLD FRONT WHICH WILL
TRY TO CROSS INTO THE AREA ON SATURDAY. WITH UPPER TROUGH RELOADING
ACROSS THE GREAT LAKES...MID LEVEL WINDS WILL REMAIN OUT OF THE WSW
WHICH WILL INHIBIT THIS FRONT FROM MAKING ANY NOTICEABLE IMPACT TO
THIS AREA...AND ANY COOLER AIR AND/OR PRECIP WILL BE DISPLACED NORTH
OF THE CWA.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
AS OF 14Z...MODELS ARE NOT IN GOOD AGREEMENT WITH PRECIPITATION
TODAY...AT ALL. NAM IS VERY BULLISH WITH PRECIPITATION ON AND OFF
FOR MOST OF THE NEXT 24 HOURS...WHILE THE GFS HAS HARDLY ANY THING
AT ALL. THE HRRR HAS THE PRECIPITATION WEST OF LBT WEAKENING OVER
THE NEXT FEW HOURS. THE WRF SEEMS TO BE THE MOST REASONABLE...WITH
SCATTERED CONVECTION FIRING NEAR THE COAST AND WORKING NORTHWEST
OVER TIME. THE MVFR CEILINGS ARE FEW AND FAR BETWEEN...SO WENT WITH
MAINLY VFR THIS MORNING. AS THE WARM FRONT LIFTS NORTHWARD...WINDS
WILL INCREASE AND BECOME MORE SOUTHERLY THROUGH TIME. TONIGHT...DEEP
MOISTURE APPROACHES OUT AHEAD OF A DEEPENING LOW. LOOK FOR MODERATE
TO HEAVY PRECIP TO MOVE INTO THE WESTERN TERMINALS TOWARD THE END OF
THE FORECAST PERIOD...WITH ONLY ISOLATED ACTIVITY ALONG THE COAST.
IFR CONDITIONS ARE POSSIBLE INLAND...BUT SHOULD BE PREDOMINATELY
MVFR.
THE EXTENDED OUTLOOK...SHRA/TSRA ON TUESDAY WITH MODERATE
CONFIDENCE FOR INTERMITTENT IFR CONDITIONS. CONVECTION WILL
CONTINUE INTO WEDNESDAY WITH IMPROVING CONDITIONS THURSDAY INTO
SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 AM MONDAY...SCA ALL WATERS FOR LATE TONIGHT. SE-S WINDS 10
KT...WILL BECOME SOUTHERLY 10-15 KT THIS AFTERNOON...THEN 15 TO 20
KT TONIGHT AHEAD OF AN APPROACHING SURFACE COLD FRONT FROM THE WEST.
SIGNIFICANT SEAS INITIALLY 2 TO 4 FT...WILL BUILD TO 4 TO 6 FT
ACROSS THE WATERS BY DAYBREAK TUESDAY.
WIND FIELDS SEVERAL HUNDRED FEET OFF THE SURFACE WILL REACH 40 KT
AFTER MIDNIGHT TONIGHT. AS A RESULT...CONVECTION THAT TRAVERSES THE
ILM WATERS WILL TAP INTO THESE HIGHER WINDS AND POTENTIALLY DROP
THEM TO THE OCEAN SFC WITH STRONG WIND GUSTS. FAVORABLE LOW-LEVEL
WIND SHEAR/HODOGRAPHS WILL FAVOR ROTATING OR STRONG TSTMS LATE
TONIGHT INTO EARLY TUESDAY.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...STRONG SOUTHERLY WINDS AHEAD OF A POTENT COLD
FRONT WILL CREATE SMALL CRAFT ADVISORY CONDITIONS THROUGH MUCH OF
TUESDAY. WINDS OF 15-25 KTS WILL HELP BUILD SEAS TO 4-6 FT...HIGHEST
ACROSS THE NORTHERN WATERS. WAVES WILL BE FORMED BY A COMBINATION OF
A WEAK SE SWELL AND THE MORE DOMINANT 6 SEC SOUTHERLY WIND
WAVES...SO EXPECT RELATIVELY STEEP WAVE FACES THROUGH THE DAY.
ADDITIONALLY...STRONG THUNDERSTORMS ARE POSSIBLE AHEAD OF THE COLD
FRONT AS IT ADVANCES EASTWARD THROUGH THE EVENING. THESE STORMS
COULD PRODUCE MUCH STRONGER WIND GUSTS AND TORRENTIAL RAINFALL...AS
WELL AS LOCALLY ENHANCED WAVE HEIGHTS.
WINDS TURN WESTERLY EARLY WEDNESDAY WITH THE FRONT AND THEN BECOME
LIGHT AND VARIABLE AS THE BOUNDARY WAVERS OVER THE COASTAL WATERS.
BY LATE WEDNESDAY WINDS WILL BECOME NE...BUT REMAIN LESS THAN 10
KTS. SEAS FALL QUICKLY DURING THE DAY...FROM 3-5 FT EARLY TO 2-3 FT
LATE...THANKS TO THE EASING WIND SPEEDS.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 300 AM MONDAY...HIGH PRESSURE RIDGES DOWN THE COAST THURSDAY
BEFORE DRIFTING OFFSHORE FRIDAY. NE WINDS OF AROUND 10 KTS PERSIST
MUCH OF THURSDAY BEFORE THE GRADIENT RELAXES...ALLOWING WINDS TO
BECOME LIGHT AND VARIABLE FRIDAY...BEFORE FINALLY TURNING TO THE SE
AT THE END OF THE PERIOD. WAVE GUIDANCE SHOWS SEVERAL DIFFERENT WAVE
GROUPS PRESENT IN THE SPECTRUM THROUGH THE EXTENDED...WITH NO GROUP
BECOMING DOMINANT. WITHOUT ANY MEANINGFUL SWELL OR PRESSURE
GRADIENT...SEAS WILL BE 1-3 FT THURSDAY...AND ONLY 1-2 FT ON FRIDAY.
&&
.TIDES/COASTAL FLOODING...
AS OF 350 AM MONDAY...BETWEEN 10 AM AND NOON TODAY...PROGGED MDL
WILMINGTON TIDE GAGE FORECASTS INDICATE A THREAT FOR GAGE READINGS
ABOVE THE 5.50 FT MLLW COASTAL FLOOD ADVISORY THRESHOLD BETWEEN 10
AM AND NOON TODAY. A PEAK OF 5.60 FT MLLW IS FORECAST AROUND 11
AM. THE PRONE LOCATIONS TO THIS TYPE OF SHALLOW FLOODING WILL
INCLUDE AREAS BORDERING ALONG THE CAPE FEAR RIVER SUCH AS WATER
STREET OF DOWNTOWN WILMINGTON... ROADWAYS LEADING TO AND FROM THE
USS NORTH CAROLINA BATTLESHIP... AND CANAL ROAD IN CAROLINA BEACH.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...COASTAL FLOOD ADVISORY FROM 10 AM THIS MORNING TO NOON EDT
TODAY FOR NCZ107-108.
MARINE...SMALL CRAFT ADVISORY FROM 5 AM TUESDAY TO 5 AM EDT WEDNESDAY
FOR AMZ250-252-254-256.
&&
$$
NEAR TERM...8
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...43
TIDES/COASTAL FLOODING...DCH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
716 AM EDT MON SEP 17 2012
.SYNOPSIS...
HIGH PRESSURE WILL DRIFT OFF THE CAROLINA COASTS TODAY AS A COLD
FRONT APPROACHES FROM THE WEST. LOW PRESSURE WILL MOVE THROUGH THE
WESTERN CAROLINAS TUESDAY...DRAGGING A STRONG COLD FRONT ACROSS
THE AREA. THIS COLD FRONT WILL PRODUCE WIDESPREAD SHOWERS AND
THUNDERSTORMS...SOME OF WHICH COULD BE STRONG. COLD FRONT WILL
LINGER NEAR THE COAST WEDNESDAY...BEFORE HIGH PRESSURE BRINGS
COOLER AND DRIER WEATHER INTO THE AREA FOR LATE WEEK AND THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 640 AM MONDAY...SFC WIND FIELD VIA LATEST HRRR INDICATES A
SFC BOUNDARY LYING ACROSS THE FA THIS MORNING...WHICH SHOULD
TRANSITION INTO A WARM FRONT AND LIFT NORTH OF THE FA MIDDAY
THROUGH THIS AFTERNOON. THE BEST SYNOPTIC LIFT UVVS WILL LIE ALONG
AND NORTH OF THIS BOUNDARY...MUCH OF THE UVVS COMING FROM THE
DYNAMICS ASSOCIATED WITH WEAK MID-LEVEL S/W TROFS/IMPULSES MOVING
EASTWARD ACROSS THE NORTHERN HALF OF NC. HAVE ADJUSTED THE HIGHER
POPS MAINLY ALONG AND NORTH OF THE ILM NC-SC BORDER FOR TODAY.
VIA VARIOUS MODEL TIME HEIGHT SECTIONS ACROSS THE FA...MID AND
HIGH LEVEL CLOUDS WILL BLANKET MUCH OF THE AREA TODAY. THIS IN
TURN WILL BLOCK A GOOD AMOUNT OF THE DAYS INSOLATION...RESULTING
WITH BORDERLINE WEAK INSTABILITY FOR CONVECTION. MAXES TO RANGE
FROM AROUND 80 NORTHERN PORTIONS...TO THE MID 80S SOUTHERN
PORTIONS.
FOR TONIGHT...THE MID AND UPPER LEVEL RIDGE AXIS MOVES OFF THE
COAST ALLOWING THE MID LEVEL S/W TROF ALONG THE US NW GULF COAST
TO TRACK EASTWARD...AND BEGIN TO PHASE WITH THE EXPANDING AND
DEEPENING HUDSON BAY/GREAT LAKES MID-UPPER LEVEL TROF. EARLY THIS
EVENING...SFC THRU 8H FLOW WILL HAVE TAPPED BOTH ATLANTIC AND GULF
OF MEXICO MOISTURE. AFTER MIDNIGHT...FLOW ABOVE 7H WILL HAVE
FURTHER TAPPED GULF OF MEXICO AND EVENTUALLY ATLANTIC MOISTURE
BY DAYBREAK. LOOK FOR MODEL PROGGED SOUNDING PWS TO EASILY
SURPASS 2.00 INCHES OVERNIGHT. WILL INDICATE INCREASING POPS DURING
TONIGHT...WITH HEAVY RAIN POSSIBLE FROM ANY CONVECTION. LOOK FOR A
SOMEWHAT FAVORABLE LOW LEVEL HODOGRAPHS FOR ONSHORE MOVEMENT OF
ROTATING THUNDERSTORMS BETWEEN MIDNIGHT TONIGHT TO UP TO SEVERAL
HRS AFTER DAYBREAK TUESDAY. ISOLATED CONVECTION THAT MOVES ONSHORE
LATE TONIGHT WILL BE THE ACTIVITY SUSCEPTIBLE TO PRODUCE THE
ISOLATED WATERSPOUT/TORNADO AS WELL AS DAMAGING WIND GUSTS. HAVE
PLACED ITS REMOTE POSSIBILITY WITHIN THE HWO. DECENT WAA TONIGHT
UNDER DEVELOPING STRONG ONSHORE SOUTHERLY WINDS...WILL PRODUCE MIN
TEMPS IN THE 70S THRU OUT THE FA.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...STRONG COLD FRONT STILL PROGGED TO CROSS THE
AREA TUESDAY BRINGING WIDESPREAD SHOWERS/TSTMS...POTENTIALLY WITH
DAMAGING WINDS AND HEAVY RAIN TO THE AREA...IN AN EARLY SEASON
HIGH SHEAR LOW CAPE EVENT.
PHASING OCCURRING AT 500MB TUESDAY BETWEEN SOUTHERN AND NORTHERN
STREAM IMPULSES CREATES A HIGHLY AMPLIFIED TROUGH ACROSS THE EASTERN
CONUS. SURFACE LOW RIDES UP THE APPALACHIANS AND DRIVES A COLD ACROSS
THE CAROLINAS. STRONG LOW LEVEL WINDS...APPROACHING 50 KTS AT
850MB...ADVECT COPIOUS MOISTURE INTO THE COLUMN AND STRONG MID-LEVEL
THETA-E ADVECTION OCCURS AHEAD OF THIS FRONT. SPC HAS PLACED THE
ENTIRE AREA IN A SLIGHT RISK FOR TUESDAY...30% PROBABILITIES ACROSS
THE I-95 COUNTIES...AND THIS SEEMS WARRANTED BASED OFF THE STRONG
LOW LEVEL WIND FIELDS.
DO NOT EXPECT WIDESPREAD SEVERE WINDS TUESDAY...BUT ISOLATED TO
POTENTIALLY SCATTERED DAMAGING WIND GUSTS ARE POSSIBLE. 0-6KM BULK
SHEAR RISES TO AROUND 30 KTS WHICH COULD SUPPORT MULTICELL CLUSTERS
WITH STRONG WINDS IN A UNIDIRECTIONAL SHEAR ENVIRONMENT...AND
FORECAST SBCAPE RISES TO AROUND 1000 J/KG AHEAD OF THE FRONT.
HOWEVER...DCAPE IS MINIMAL...UPPER FORCING LAGS BEHIND THE BEST
SURFACE DYNAMICS...AND FRONT ITSELF WILL CROSS DURING THE NIGHTTIME
HOURS...ALTHOUGH WITH STRONG THETA-E ADVECTION OCCURRING RIGHT UP
UNTIL FROPA...CONVECTION MAY SUSTAIN ITSELF WELL PAST NIGHTFALL.
SO...CANNOT RULE OUT A FEW DAMAGING WIND GUSTS...ESPECIALLY SINCE
SUSTAINED GRADIENT WINDS WILL LIKELY BE AROUND 20 MPH TO BEGIN
WITH...AND IT WILL NOT TAKE AN INCREDIBLY STRONG STORM TO MIX DOWN
THE LLJ WINDS. STILL...DO NOT ANTICIPATE A WIDESPREAD SEVERE WEATHER
EVENT IN THE ILM CWA...SINCE BEST COMBINATION OF FORCING SHOULD BE
DISPLACED NW OF THIS AREA. HEAVY RAIN ON THE OTHER HAND WILL BE THE
MORE SIGNIFICANT THREAT...WITH TORRENTIAL RAINFALL LIKELY IN
CONVECTION.
FRONT CROSSES THE AREA VERY EARLY WEDNESDAY...BUT INDICATIONS ARE
NOW THAT IT WILL HANG BACK NEAR THE COAST AS A SECONDARY LOW
DEVELOPS ACROSS THE SOUTHEAST AND UPPER TROUGHING LAGS BEHIND. THIS
WILL KEEP PRECIP CHANCES THROUGHOUT THE SHORT TERM...ALTHOUGH MUCH
LIGHTER QPF EXPECTED WEDNESDAY...HIGHEST NEAR THE COAST.
FORECAST PROFILES SUGGEST A WEAK WEDGE SCENARIO (RARE FOR THIS EARLY
IN THE SEASON) DEVELOPING WEDNESDAY NIGHT AS HIGH PRESSURE SETTLES
DOWN THE COAST WHILE SW FLOW REMAINS ABOVE 900MB. THIS SUGGESTS SOME
LIGHT RAIN OR EVEN DRIZZLE POTENTIALLY PERSISTING THROUGH THE END OF
THE PERIOD. VERY DRY AIR ABOVE THE WEDGE...PLUS THIS BEING OUT OF
SEASON...MEANS THAT ONLY SCHC POP WILL BE CONTINUED THROUGH THE END
OF THE SHORT TERM BUT CLOUD COVER SHOULD BE PRETTY
SIGNIFICANT...ESPECIALLY NEAR THE COAST.
HIGH TEMPS TUESDAY WILL BE RIGHT AROUND CLIMO...LOW 80S...AS STRONG
WAA IS COUNTERACTED BY CLOUD COVER AND SHOWERS...WHILE NIGHTTIME
MINS WILL BE HELD WELL ABOVE NORMAL...ONLY FALLING TO THE UPPER
60S/LOW 70S. WEDNESDAY WILL BE COOLER BEHIND THE FRONT...AROUND 80
FOR HIGHS AND NEAR 60 FOR LOWS AWAY FROM THE IMMEDIATE COAST.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 300 AM MONDAY...FRONT HOVERING JUST OFFSHORE MAY ALLOW FOR
CONTINUED SHOWERS NEAR THE COAST ON THURSDAY. FORECAST PROFILES DRY
OUT CONSIDERABLY HOWEVER...AND WILL DROP INHERITED CHC TO JUST SCHC
ON THE COAST...SILENT INLAND. BEST CHANCE WILL BE DURING THE EARLY
PART OF THE DAY BEFORE HIGH PRESSURE MORE FIRMLY RIDGES DOWN THE
COAST FORCING THE FRONT FURTHER OFFSHORE. OTHERWISE...THE EXTENDED
FEATURES DRY AND SEASONABLE WEATHER AS HIGH PRESSURE DOMINATES AT
THE SURFACE AND A LARGE UPPER TROUGH PERSISTS OVER THE EASTERN HALF
OF THE COUNTRY. ONLY FEATURE OF INTEREST IS A COLD FRONT WHICH WILL
TRY TO CROSS INTO THE AREA ON SATURDAY. WITH UPPER TROUGH RELOADING
ACROSS THE GREAT LAKES...MID LEVEL WINDS WILL REMAIN OUT OF THE WSW
WHICH WILL INHIBIT THIS FRONT FROM MAKING ANY NOTICEABLE IMPACT TO
THIS AREA...AND ANY COOLER AIR AND/OR PRECIP WILL BE DISPLACED NORTH
OF THE CWA.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AS OF 12Z...MODELS ARE NOT IN GOOD AGREEMENT WITH PRECIPITATION
TODAY...AT ALL. NAM IS VERY BULLISH WITH PRECIPITATION ON AND OFF
FOR MOST OF THE NEXT 24 HOURS...WHILE THE GFS HAS HARDLY ANY THING
AT ALL. THE HRRR HAS THE PRECIPITATION WEST OF LBT WEAKENING OVER
THE NEXT FEW HOURS. THE WRF SEEMS TO BE THE MOST REASONABLE...WITH
SCATTERED CONVECTION FIRING NEAR THE COAST AND WORKING NORTHWEST
OVER TIME. THE MVFR CEILINGS ARE FEW AND FAR BETWEEN...SO WENT WITH
MAINLY VFR THIS MORNING. AS THE WARM FRONT LIFTS NORTHWARD...WINDS
WILL INCREASE AND BECOME MORE SOUTHERLY THROUGH TIME. TONIGHT...DEEP
MOISTURE APPROACHES OUT AHEAD OF A DEEPENING LOW. LOOK FOR MODERATE
TO HEAVY PRECIP TO MOVE INTO THE WESTERN TERMINALS TOWARD THE END OF
THE FORECAST PERIOD...WITH ONLY ISOLATED ACTIVITY ALONG THE COAST.
IFR CONDITIONS ARE POSSIBLE INLAND...BUT SHOULD BE PREDOMINATELY
MVFR.
THE EXTENDED OUTLOOK...SHRA/TSRA ON TUESDAY WITH MODERATE
CONFIDENCE FOR INTERMITTENT IFR CONDITIONS. CONVECTION WILL
CONTINUE INTO WEDNESDAY WITH IMPROVING CONDITIONS THURSDAY INTO
SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 640 AM MONDAY...SCA RAISED FOR ALL ILM WATERS FOR LATE
TONIGHT. SE-S WINDS 10 KT...WILL BECOME SOUTHERLY 10-15 KT BY THIS
AFTERNOON...AND FURTHER INCREASE TO 15 TO 20 KT TONIGHT. THIS IN
RESPONSE TO AN ORGANIZING SFC PRESSURE PATTERN...AND TIGHTENING SFC
PRESSURE GRADIENT DEVELOPING AHEAD OF THE APPROACHING SURFACE COLD
FRONT FROM THE WEST. SIGNIFICANT SEAS WILL INITIALLY COMMENCE AT 2
TO 4 FT...MAINLY COMPRISED OF A 10-12 SECOND SE SWELL. WITH
INCREASING WINDS LATER TODAY AND TONIGHT...LOCALLY PRODUCED WIND
DRIVEN WAVES AT 4 TO 7 SECOND AVERAGE PERIODS WILL BECOME MORE
DOMINANT. AT THIS POINT...SWAN ADVERTISES SIG. SEAS REACHING 4 TO
6 FT ACROSS ALL WATERS JUST PRIOR TO DAYBREAK TUE...HENCE HAVE
RAISED THE SCA. WIND FIELDS JUST OFF THE DECK ARE PROGGED TO
REACH 40 KT AFTER MIDNIGHT TONIGHT. AS A RESULT...CONVECTION THAT
TRAVERSES THE ILM WATERS WILL TAP INTO THESE HIGHER WINDS AND
POTENTIALLY DROP THEM TO THE OCEAN SFC AS WIND GUSTS 35 KT OR
GREATER. FAVORABLE LOW LEVEL WIND SHEAR AND HODOGRAPHS WILL AID
ISOLATED WATERSPOUT POSSIBILITIES...MAINLY BETWEEN MIDNIGHT AND UP
TO SEVERAL HOURS AFTER DAYBREAK TUE.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...STRONG SOUTHERLY WINDS AHEAD OF A POTENT COLD
FRONT WILL CREATE SMALL CRAFT ADVISORY CONDITIONS THROUGH MUCH OF
TUESDAY. WINDS OF 15-25 KTS WILL HELP BUILD SEAS TO 4-6 FT...HIGHEST
ACROSS THE NORTHERN WATERS. WAVES WILL BE FORMED BY A COMBINATION OF
A WEAK SE SWELL AND THE MORE DOMINANT 6 SEC SOUTHERLY WIND
WAVES...SO EXPECT RELATIVELY STEEP WAVE FACES THROUGH THE DAY.
ADDITIONALLY...STRONG THUNDERSTORMS ARE POSSIBLE AHEAD OF THE COLD
FRONT AS IT ADVANCES EASTWARD THROUGH THE EVENING. THESE STORMS
COULD PRODUCE MUCH STRONGER WIND GUSTS AND TORRENTIAL RAINFALL...AS
WELL AS LOCALLY ENHANCED WAVE HEIGHTS.
WINDS TURN WESTERLY EARLY WEDNESDAY WITH THE FRONT AND THEN BECOME
LIGHT AND VARIABLE AS THE BOUNDARY WAVERS OVER THE COASTAL WATERS.
BY LATE WEDNESDAY WINDS WILL BECOME NE...BUT REMAIN LESS THAN 10
KTS. SEAS FALL QUICKLY DURING THE DAY...FROM 3-5 FT EARLY TO 2-3 FT
LATE...THANKS TO THE EASING WIND SPEEDS.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 300 AM MONDAY...HIGH PRESSURE RIDGES DOWN THE COAST THURSDAY
BEFORE DRIFTING OFFSHORE FRIDAY. NE WINDS OF AROUND 10 KTS PERSIST
MUCH OF THURSDAY BEFORE THE GRADIENT RELAXES...ALLOWING WINDS TO
BECOME LIGHT AND VARIABLE FRIDAY...BEFORE FINALLY TURNING TO THE SE
AT THE END OF THE PERIOD. WAVE GUIDANCE SHOWS SEVERAL DIFFERENT WAVE
GROUPS PRESENT IN THE SPECTRUM THROUGH THE EXTENDED...WITH NO GROUP
BECOMING DOMINANT. WITHOUT ANY MEANINGFUL SWELL OR PRESSURE
GRADIENT...SEAS WILL BE 1-3 FT THURSDAY...AND ONLY 1-2 FT ON FRIDAY.
&&
.TIDES/COASTAL FLOODING...
AS OF 350 AM MONDAY...BETWEEN 10 AM AND NOON TODAY...PROGGED MDL
WILMINGTON TIDE GAGE FORECASTS INDICATE A THREAT FOR GAGE READINGS
ABOVE THE 5.50 FT MLLW COASTAL FLOOD ADVISORY THRESHOLD BETWEEN 10
AM AND NOON TODAY. A PEAK OF 5.60 FT MLLW IS FORECAST AROUND 11
AM. THE PRONE LOCATIONS TO THIS TYPE OF SHALLOW FLOODING WILL
INCLUDE AREAS BORDERING ALONG THE CAPE FEAR RIVER SUCH AS WATER
STREET OF DOWNTOWN WILMINGTON... ROADWAYS LEADING TO AND FROM THE
USS NORTH CAROLINA BATTLESHIP... AND CANAL ROAD IN CAROLINA BEACH.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...COASTAL FLOOD ADVISORY FROM 10 AM THIS MORNING TO NOON EDT
TODAY FOR NCZ107-108.
MARINE...SMALL CRAFT ADVISORY FROM 5 AM TUESDAY TO 5 AM EDT WEDNESDAY
FOR AMZ250-252-254-256.
&&
$$
SYNOPSIS...JDW
NEAR TERM...DCH
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...43
TIDES/COASTAL FLOODING...DCH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
643 AM EDT MON SEP 17 2012
.SYNOPSIS...
HIGH PRESSURE WILL DRIFT OFF THE CAROLINA COASTS TODAY AS A COLD
FRONT APPROACHES FROM THE WEST. LOW PRESSURE WILL MOVE THROUGH THE
WESTERN CAROLINAS TUESDAY...DRAGGING A STRONG COLD FRONT ACROSS
THE AREA. THIS COLD FRONT WILL PRODUCE WIDESPREAD SHOWERS AND
THUNDERSTORMS...SOME OF WHICH COULD BE STRONG. COLD FRONT WILL
LINGER NEAR THE COAST WEDNESDAY...BEFORE HIGH PRESSURE BRINGS
COOLER AND DRIER WEATHER INTO THE AREA FOR LATE WEEK AND THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 640 AM MONDAY...SFC WIND FIELD VIA LATEST HRRR INDICATES A
SFC BOUNDARY LYING ACROSS THE FA THIS MORNING...WHICH SHOULD
TRANSITION INTO A WARM FRONT AND LIFT NORTH OF THE FA MIDDAY
THROUGH THIS AFTERNOON. THE BEST SYNOPTIC LIFT UVVS WILL LIE ALONG
AND NORTH OF THIS BOUNDARY...MUCH OF THE UVVS COMING FROM THE
DYNAMICS ASSOCIATED WITH WEAK MID-LEVEL S/W TROFS/IMPULSES MOVING
EASTWARD ACROSS THE NORTHERN HALF OF NC. HAVE ADJUSTED THE HIER
POPS MAINLY ALONG AND NORTH OF THE ILM NC-SC BORDER FOR TODAY.
VIA VARIOUS MODEL TIME HEIGHT SECTIONS ACROSS THE FA...MID AND
HIGH LEVEL CLOUDS WILL BLANKET MUCH OF THE AREA TODAY. THIS IN
TURN WILL BLOCK A GOOD AMOUNT OF THE DAYS INSOLATION...RESULTING
WITH BORDERLINE WEAK INSTABILITY FOR CONVECTION. MAXES TO RANGE
FROM AROUND 80 NORTHERN PORTIONS...TO THE MID 80S SOUTHERN
PORTIONS.
FOR TONIGHT...THE MID AND UPPER LEVEL RIDGE AXIS MOVES OFF THE
COAST ALLOWING THE MID LEVEL S/W TROF ALONG THE US NW GULF COAST
TO TRACK EASTWARD...AND BEGIN TO PHASE WITH THE EXPANDING AND
DEEPENING HUDSON BAY/GREAT LAKES MID-UPPER LEVEL TROF. EARLY THIS
EVENING...SFC THRU 8H FLOW WILL HAVE TAPPED BOTH ATLANTIC AND GULF
OF MEXICO MOISTURE. AFTER MIDNIGHT...FLOW ABOVE 7H WILL HAVE
FURTHER TAPPED GULF OF MEXICO AND EVENTUALLY ATLANTIC MOISTURE
BY DAYBREAK. LOOK FOR MODEL PROGGED SOUNDING PWS TO EASILY
SURPASS 2.00 INCHES OVERNIGHT. WILL INDICATE INCREASING POPS DURING
TONIGHT...WITH HEAVY RAIN POSSIBLE FROM ANY CONVECTION. LOOK FOR A
SOMEWHAT FAVORABLE LOW LEVEL HODOGRAPH FOR ONSHORE MOVEMENT OF
ROTATING THUNDERSTORMS BETWEEN MIDNIGHT TONIGHT TO UP TO SEVERAL
HRS AFTER DAYBREAK TUESDAY. ISOLATED CONVECTION THAT MOVES ONSHORE
LATE TONIGHT WILL BE THE ACTIVITY SUSCEPTIBLE TO PRODUCE THE
ISOLATED WATERSPOUT/TORNADO AS WELL AS DAMAGING WIND GUSTS. HAVE
PLACED ITS REMOTE POSSIBILITY WITHIN THE HWO. DECENT WAA TONIGHT
UNDER DEVELOPING STRONG ONSHORE SOUTHERLY WINDS...WILL PRODUCE MIN
TEMPS IN THE 70S THRU OUT THE FA.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...STRONG COLD FRONT STILL PROGGED TO CROSS THE
AREA TUESDAY BRINGING WIDESPREAD SHOWERS/TSTMS...POTENTIALLY WITH
DAMAGING WINDS AND HEAVY RAIN TO THE AREA...IN AN EARLY SEASON
HIGH SHEAR LOW CAPE EVENT.
PHASING OCCURRING AT 500MB TUESDAY BETWEEN SOUTHERN AND NORTHERN
STREAM IMPULSES CREATES A HIGHLY AMPLIFIED TROUGH ACROSS THE EASTERN
CONUS. SURFACE LOW RIDES UP THE APPALACHIANS AND DRIVES A COLD ACROSS
THE CAROLINAS. STRONG LOW LEVEL WINDS...APPROACHING 50 KTS AT
850MB...ADVECT COPIOUS MOISTURE INTO THE COLUMN AND STRONG MID-LEVEL
THETA-E ADVECTION OCCURS AHEAD OF THIS FRONT. SPC HAS PLACED THE
ENTIRE AREA IN A SLIGHT RISK FOR TUESDAY...30% PROBABILITIES ACROSS
THE I-95 COUNTIES...AND THIS SEEMS WARRANTED BASED OFF THE STRONG
LOW LEVEL WIND FIELDS.
DO NOT EXPECT WIDESPREAD SEVERE WINDS TUESDAY...BUT ISOLATED TO
POTENTIALLY SCATTERED DAMAGING WIND GUSTS ARE POSSIBLE. 0-6KM BULK
SHEAR RISES TO AROUND 30 KTS WHICH COULD SUPPORT MULTICELL CLUSTERS
WITH STRONG WINDS IN A UNIDIRECTIONAL SHEAR ENVIRONMENT...AND
FORECAST SBCAPE RISES TO AROUND 1000 J/KG AHEAD OF THE FRONT.
HOWEVER...DCAPE IS MINIMAL...UPPER FORCING LAGS BEHIND THE BEST
SURFACE DYNAMICS...AND FRONT ITSELF WILL CROSS DURING THE NIGHTTIME
HOURS...ALTHOUGH WITH STRONG THETA-E ADVECTION OCCURRING RIGHT UP
UNTIL FROPA...CONVECTION MAY SUSTAIN ITSELF WELL PAST NIGHTFALL.
SO...CANNOT RULE OUT A FEW DAMAGING WIND GUSTS...ESPECIALLY SINCE
SUSTAINED GRADIENT WINDS WILL LIKELY BE AROUND 20 MPH TO BEGIN
WITH...AND IT WILL NOT TAKE AN INCREDIBLY STRONG STORM TO MIX DOWN
THE LLJ WINDS. STILL...DO NOT ANTICIPATE A WIDESPREAD SEVERE WEATHER
EVENT IN THE ILM CWA...SINCE BEST COMBINATION OF FORCING SHOULD BE
DISPLACED NW OF THIS AREA. HEAVY RAIN ON THE OTHER HAND WILL BE THE
MORE SIGNIFICANT THREAT...WITH TORRENTIAL RAINFALL LIKELY IN
CONVECTION.
FRONT CROSSES THE AREA VERY EARLY WEDNESDAY...BUT INDICATIONS ARE
NOW THAT IT WILL HANG BACK NEAR THE COAST AS A SECONDARY LOW
DEVELOPS ACROSS THE SOUTHEAST AND UPPER TROUGHING LAGS BEHIND. THIS
WILL KEEP PRECIP CHANCES THROUGHOUT THE SHORT TERM...ALTHOUGH MUCH
LIGHTER QPF EXPECTED WEDNESDAY...HIGHEST NEAR THE COAST.
FORECAST PROFILES SUGGEST A WEAK WEDGE SCENARIO (RARE FOR THIS EARLY
IN THE SEASON) DEVELOPING WEDNESDAY NIGHT AS HIGH PRESSURE SETTLES
DOWN THE COAST WHILE SW FLOW REMAINS ABOVE 900MB. THIS SUGGESTS SOME
LIGHT RAIN OR EVEN DRIZZLE POTENTIALLY PERSISTING THROUGH THE END OF
THE PERIOD. VERY DRY AIR ABOVE THE WEDGE...PLUS THIS BEING OUT OF
SEASON...MEANS THAT ONLY SCHC POP WILL BE CONTINUED THROUGH THE END
OF THE SHORT TERM BUT CLOUD COVER SHOULD BE PRETTY
SIGNIFICANT...ESPECIALLY NEAR THE COAST.
HIGH TEMPS TUESDAY WILL BE RIGHT AROUND CLIMO...LOW 80S...AS STRONG
WAA IS COUNTERACTED BY CLOUD COVER AND SHOWERS...WHILE NIGHTTIME
MINS WILL BE HELD WELL ABOVE NORMAL...ONLY FALLING TO THE UPPER
60S/LOW 70S. WEDNESDAY WILL BE COOLER BEHIND THE FRONT...AROUND 80
FOR HIGHS AND NEAR 60 FOR LOWS AWAY FROM THE IMMEDIATE COAST.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 300 AM MONDAY...FRONT HOVERING JUST OFFSHORE MAY ALLOW FOR
CONTINUED SHOWERS NEAR THE COAST ON THURSDAY. FORECAST PROFILES DRY
OUT CONSIDERABLY HOWEVER...AND WILL DROP INHERITED CHC TO JUST SCHC
ON THE COAST...SILENT INLAND. BEST CHANCE WILL BE DURING THE EARLY
PART OF THE DAY BEFORE HIGH PRESSURE MORE FIRMLY RIDGES DOWN THE
COAST FORCING THE FRONT FURTHER OFFSHORE. OTHERWISE...THE EXTENDED
FEATURES DRY AND SEASONABLE WEATHER AS HIGH PRESSURE DOMINATES AT
THE SURFACE AND A LARGE UPPER TROUGH PERSISTS OVER THE EASTERN HALF
OF THE COUNTRY. ONLY FEATURE OF INTEREST IS A COLD FRONT WHICH WILL
TRY TO CROSS INTO THE AREA ON SATURDAY. WITH UPPER TROUGH RELOADING
ACROSS THE GREAT LAKES...MID LEVEL WINDS WILL REMAIN OUT OF THE WSW
WHICH WILL INHIBIT THIS FRONT FROM MAKING ANY NOTICEABLE IMPACT TO
THIS AREA...AND ANY COOLER AIR AND/OR PRECIP WILL BE DISPLACED NORTH
OF THE CWA.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AS OF 06Z...PERIODS OF MVFR/IFR OVERNIGHT AND INTO THE EARLY MORNING
HOURS WITH VCSH/SCATTERED SHRA AND POTENTIAL BR/LOW CIGS INLAND.
FOR SEVERAL HRS AFTER DAYBREAK...EXPECT VFR/MVFR WITH BRIEF
PERIODS OF IFR DUE TO SHRA/BR. FOR THE AFTERNOON/EVENING VFR WITH
BRIEF PERIODS OF MVFR/IFR FROM CONVECTION.
SHRA AND VCSH WILL CONTINUE THROUGH THE OVERNIGHT HOURS THROUGH
MID-MORNING. LOOKING AT NE-E LIGHT WINDS OVERNIGHT WITH THE BEST
CHANCE FOR LOW CEILINGS/FOG ACROSS THE INLAND SITES BEFORE
SUNRISE. AFTER DAYBREAK...LINGERING MVFR/IFR FOG WILL DISSIPATE
AND CIGS WILL LIFT GIVING WAY TO VFR. LOW TO MID SCT/BKN CLOUDS
WILL CONTINUE THROUGHOUT THE DAY WITH A CHANCE FOR MVFR FROM
SHRA/TSRA ACROSS THE AREA. EAST-SOUTHEAST WINDS WILL INCREASE TO
AOB 10 KTS BY THE AFTERNOON HOURS...BECOMING SOUTHERLY ALONG THE
COAST WITH GUSTS 15 TO 20 KTS. INTO THE EVENING HOURS...SHRA/TSRA
WILL GRADUALLY QUIET DOWN...EXCEPT FOR CONVECTIVE ACTIVITY OFF THE
ATL WATERS THAT COULD MOVE ONSHORE BY MIDNIGHT DUE TO A DEEPER
ONSHORE FLOW MATERIALIZING. SOUTHERLY WINDS TO INCREASE TO
SUSTAINED 10 KT BY MIDNIGHT...ESPECIALLY AT THE COASTAL TERMS.
THE EXTENDED OUTLOOK...SHRA/TSRA ON TUESDAY WITH MODERATE
CONFIDENCE FOR INTERMITTENT IFR CONDITIONS. CONVECTION WILL
CONTINUE INTO WEDNESDAY WITH IMPROVING CONDITIONS THURSDAY INTO
SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 640 AM MONDAY...SCA RAISED FOR ALL ILM WATERS FOR LATE
TONIGHT. SE-S WINDS 10 KT...WILL BECOME SOUTHERLY 10-15 KT BY THIS
AFTERNOON...AND FURTHER INCREASE TO 15 TO 20 KT TONIGHT. THIS IN
RESPONSE TO AN ORGANIZING SFC PRESSURE PATTERN...AND TIGHTENING SFC
PRESSURE GRADIENT DEVELOPING AHEAD OF THE APPROACHING SURFACE COLD
FRONT FROM THE WEST. SIGNIFICANT SEAS WILL INITIALLY COMMENCE AT 2
TO 4 FT...MAINLY COMPRISED OF A 10-12 SECOND SE SWELL. WITH
INCREASING WINDS LATER TODAY AND TONIGHT...LOCALLY PRODUCED WIND
DRIVEN WAVES AT 4 TO 7 SECOND AVERAGE PERIODS WILL BECOME MORE
DOMINANT. AT THIS POINT...SWAN ADVERTIZES SIG. SEAS REACHING 4 TO
6 FT ACROSS ALL WATERS JUST PRIOR TO DAYBREAK TUE...HENCE HAVE
RAISED THE SCA. WIND FIELDS JUST OFF THE DECK ARE PROGGED TO
REACH 40 KT AFTER MIDNIGHT TONIGHT. AS A RESULT...CONVECTION THAT
TRAVERSES THE ILM WATERS WILL TAP INTO THESE HIER WINDS AND
POTENTIALLY DROP THEM TO THE OCEAN SFC AS WIND GUSTS 35 KT OR
GREATER. FAVORABLE LOW LEVEL WIND SHEAR AND HODOGRAPH WILL AID
ISOLATED WATERSPOUT POSSIBILITIES...MAINLY BETWEEN MIDNIGHT AND UP
TO SEVERAL HOURS AFTER DAYBREAK TUE.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...STRONG SOUTHERLY WINDS AHEAD OF A POTENT COLD
FRONT WILL CREATE SMALL CRAFT ADVISORY CONDITIONS THROUGH MUCH OF
TUESDAY. WINDS OF 15-25 KTS WILL HELP BUILD SEAS TO 4-6 FT...HIGHEST
ACROSS THE NORTHERN WATERS. WAVES WILL BE FORMED BY A COMBINATION OF
A WEAK SE SWELL AND THE MORE DOMINANT 6 SEC SOUTHERLY WIND
WAVES...SO EXPECT RELATIVELY STEEP WAVE FACES THROUGH THE DAY.
ADDITIONALLY...STRONG THUNDERSTORMS ARE POSSIBLE AHEAD OF THE COLD
FRONT AS IT ADVANCES EASTWARD THROUGH THE EVENING. THESE STORMS
COULD PRODUCE MUCH STRONGER WIND GUSTS AND TORRENTIAL RAINFALL...AS
WELL AS LOCALLY ENHANCED WAVE HEIGHTS.
WINDS TURN WESTERLY EARLY WEDNESDAY WITH THE FRONT AND THEN BECOME
LIGHT AND VARIABLE AS THE BOUNDARY WAVERS OVER THE COASTAL WATERS.
BY LATE WEDNESDAY WINDS WILL BECOME NE...BUT REMAIN LESS THAN 10
KTS. SEAS FALL QUICKLY DURING THE DAY...FROM 3-5 FT EARLY TO 2-3 FT
LATE...THANKS TO THE EASING WIND SPEEDS.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 300 AM MONDAY...HIGH PRESSURE RIDGES DOWN THE COAST THURSDAY
BEFORE DRIFTING OFFSHORE FRIDAY. NE WINDS OF AROUND 10 KTS PERSIST
MUCH OF THURSDAY BEFORE THE GRADIENT RELAXES...ALLOWING WINDS TO
BECOME LIGHT AND VARIABLE FRIDAY...BEFORE FINALLY TURNING TO THE SE
AT THE END OF THE PERIOD. WAVE GUIDANCE SHOWS SEVERAL DIFFERENT WAVE
GROUPS PRESENT IN THE SPECTRUM THROUGH THE EXTENDED...WITH NO GROUP
BECOMING DOMINANT. WITHOUT ANY MEANINGFUL SWELL OR PRESSURE
GRADIENT...SEAS WILL BE 1-3 FT THURSDAY...AND ONLY 1-2 FT ON FRIDAY.
&&
.TIDES/COASTAL FLOODING...
AS OF 350 AM MONDAY...BETWEEN 10 AM AND NOON TODAY...PROGGED MDL
WILMINGTON TIDE GAGE FORECASTS INDICATE A THREAT FOR GAGE READINGS
ABOVE THE 5.50 FT MLLW COASTAL FLOOD ADVISORY THRESHOLD BETWEEN 10
AM AND NOON TODAY. A PEAK OF 5.60 FT MLLW IS FORECAST AROUND 11
AM. THE PRONE LOCATIONS TO THIS TYPE OF SHALLOW FLOODING WILL
INCLUDE AREAS BORDERING ALONG THE CAPE FEAR RIVER SUCH AS WATER
STREET OF DOWNTOWN WILMINGTON... ROADWAYS LEADING TO AND FROM THE
USS NORTH CAROLINA BATTLESHIP... AND CANAL ROAD IN CAROLINA BEACH.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...COASTAL FLOOD ADVISORY FROM 10 AM THIS MORNING TO NOON EDT
TODAY FOR NCZ107-108.
MARINE...SMALL CRAFT ADVISORY FROM 5 AM TUESDAY TO 5 AM EDT WEDNESDAY
FOR AMZ250-252-254-256.
&&
$$
SYNOPSIS...JDW
NEAR TERM...DCH
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...DCH/SGL
TIDES/COASTAL FLOODING...DCH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
527 AM EDT MON SEP 17 2012
.SYNOPSIS...
HIGH PRESSURE WILL DRIFT OFF THE CAROLINA COASTS TODAY AS A COLD
FRONT APPROACHES FROM THE WEST. LOW PRESSURE WILL MOVE THROUGH THE
WESTERN CAROLINAS TUESDAY...DRAGGING A STRONG COLD FRONT ACROSS
THE AREA. THIS COLD FRONT WILL PRODUCE WIDESPREAD SHOWERS AND
THUNDERSTORMS...SOME OF WHICH COULD BE STRONG. COLD FRONT WILL
LINGER NEAR THE COAST WEDNESDAY...BEFORE HIGH PRESSURE BRINGS
COOLER AND DRIER WEATHER INTO THE AREA FOR LATE WEEK AND THE
WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 440 AM MONDAY...SFC WIND FIELD VIA LATEST HRRR INDICATES A
SFC BOUNDARY LYING ACROSS THE FA THIS MORNING...WHICH SHOULD
TRANSITION INTO A WARM FRONT AND LIFT NORTH OF THE FA BY MIDDAY
THROUGH THIS AFTERNOON. THE BEST SYNOPTIC LIFT UVVS WILL LIE ALONG
AND NORTH OF THIS FRONT...MUCH OF IT FROM WEAK MID-LEVEL S/W
TROFS/IMPULSES MOVING EASTWARD ACROSS THE NORTHERN HALF OF NC.
HAVE ADJUSTED THE HIER POPS MAINLY ALONG AND NORTH OF THE ILM NC-
SC BORDER FOR TODAY. VIA VARIOUS MODEL TIME HEIGHT SECTIONS ACROSS
THE FA...MID AND HIGH LEVEL CLOUDS WILL BLANKET MUCH OF THE AREA
TODAY. THIS IN TURN WILL BLOCK A GOOD AMOUNT OF THE DAYS
INSOLATION...RESULTING WITH BORDERLINE WEAK INSTABILITY FOR
CONVECTION.
FOR TONIGHT...THE MID AND UPPER LEVEL RIDGE AXIS MOVES OFF THE
COAST ALLOWING THE MID LEVEL S/W TROF ALONG THE US NW GULF COAST
TO TRACK EASTWARD...AND BEGIN TO PHASE WITH THE EXPANDING AND
DEEPENING HUDSON BAY/GREAT LAKES MID-UPPER LEVEL TROF. EARLY THIS
EVENING...SFC THRU 8H FLOW WILL HAVE TAPPED BOTH ATLANTIC AND GULF
OF MEXICO MOISTURE. AFTER MIDNIGHT...FLOW ABOVE 7H WILL HAVE
FURTHER TAPPED GULF OF MEXICO AND EVENTUALLY ATLANTIC MOISTURE
BY DAYBREAK. LOOK FOR MODEL PROGGED SOUNDING PWS TO EASILY
SURPASS 2.00 INCHES. WILL INDICATE INCREASING POPS DURING
TONIGHT...WITH HEAVY RAIN POSSIBLE FROM ANY CONVECTION. LOOK FOR A
SOMEWHAT FAVORABLE LOW LEVEL HODOGRAPH FOR ROTATING THUNDERSTORMS
BETWEEN MIDNIGHT TONIGHT AND UP TO SEVERAL HRS AFTER DAYBREAK
TUESDAY. ISOLATED CONVECTION THAT MOVES ONSHORE LATE TONIGHT WILL
BE THE ACTIVITY SUSCEPTIBLE TO PRODUCE THE ISOLATED WATERSPOUT/TORNADO
... AS WELL AS DAMAGING WIND GUSTS. HAVE PLACED ITS REMOTE POSSIBILITY
WITHIN THE HWO.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...STRONG COLD FRONT STILL PROGGED TO CROSS THE
AREA TUESDAY BRINGING WIDESPREAD SHOWERS/TSTMS...POTENTIALLY WITH
DAMAGING WINDS AND HEAVY RAIN TO THE AREA...IN AN EARLY SEASON
HIGH SHEAR LOW CAPE EVENT.
PHASING OCCURRING AT 500MB TUESDAY BETWEEN SOUTHERN AND NORTHERN
STREAM IMPULSES CREATES A HIGHLY AMPLIFIED TROUGH ACROSS THE EASTERN
CONUS. SURFACE LOW RIDES UP THE APPALACHIANS AND DRIVES A COLD ACROSS
THE CAROLINAS. STRONG LOW LEVEL WINDS...APPROACHING 50 KTS AT
850MB...ADVECT COPIOUS MOISTURE INTO THE COLUMN AND STRONG MID-LEVEL
THETA-E ADVECTION OCCURS AHEAD OF THIS FRONT. SPC HAS PLACED THE
ENTIRE AREA IN A SLIGHT RISK FOR TUESDAY...30% PROBABILITIES ACROSS
THE I-95 COUNTIES...AND THIS SEEMS WARRANTED BASED OFF THE STRONG
LOW LEVEL WIND FIELDS.
DO NOT EXPECT WIDESPREAD SEVERE WINDS TUESDAY...BUT ISOLATED TO
POTENTIALLY SCATTERED DAMAGING WIND GUSTS ARE POSSIBLE. 0-6KM BULK
SHEAR RISES TO AROUND 30 KTS WHICH COULD SUPPORT MULTICELL CLUSTERS
WITH STRONG WINDS IN A UNIDIRECTIONAL SHEAR ENVIRONMENT...AND
FORECAST SBCAPE RISES TO AROUND 1000 J/KG AHEAD OF THE FRONT.
HOWEVER...DCAPE IS MINIMAL...UPPER FORCING LAGS BEHIND THE BEST
SURFACE DYNAMICS...AND FRONT ITSELF WILL CROSS DURING THE NIGHTTIME
HOURS...ALTHOUGH WITH STRONG THETA-E ADVECTION OCCURRING RIGHT UP
UNTIL FROPA...CONVECTION MAY SUSTAIN ITSELF WELL PAST NIGHTFALL.
SO...CANNOT RULE OUT A FEW DAMAGING WIND GUSTS...ESPECIALLY SINCE
SUSTAINED GRADIENT WINDS WILL LIKELY BE AROUND 20 MPH TO BEGIN
WITH...AND IT WILL NOT TAKE AN INCREDIBLY STRONG STORM TO MIX DOWN
THE LLJ WINDS. STILL...DO NOT ANTICIPATE A WIDESPREAD SEVERE WEATHER
EVENT IN THE ILM CWA...SINCE BEST COMBINATION OF FORCING SHOULD BE
DISPLACED NW OF THIS AREA. HEAVY RAIN ON THE OTHER HAND WILL BE THE
MORE SIGNIFICANT THREAT...WITH TORRENTIAL RAINFALL LIKELY IN
CONVECTION.
FRONT CROSSES THE AREA VERY EARLY WEDNESDAY...BUT INDICATIONS ARE
NOW THAT IT WILL HANG BACK NEAR THE COAST AS A SECONDARY LOW
DEVELOPS ACROSS THE SOUTHEAST AND UPPER TROUGHING LAGS BEHIND. THIS
WILL KEEP PRECIP CHANCES THROUGHOUT THE SHORT TERM...ALTHOUGH MUCH
LIGHTER QPF EXPECTED WEDNESDAY...HIGHEST NEAR THE COAST.
FORECAST PROFILES SUGGEST A WEAK WEDGE SCENARIO (RARE FOR THIS EARLY
IN THE SEASON) DEVELOPING WEDNESDAY NIGHT AS HIGH PRESSURE SETTLES
DOWN THE COAST WHILE SW FLOW REMAINS ABOVE 900MB. THIS SUGGESTS SOME
LIGHT RAIN OR EVEN DRIZZLE POTENTIALLY PERSISTING THROUGH THE END OF
THE PERIOD. VERY DRY AIR ABOVE THE WEDGE...PLUS THIS BEING OUT OF
SEASON...MEANS THAT ONLY SCHC POP WILL BE CONTINUED THROUGH THE END
OF THE SHORT TERM BUT CLOUD COVER SHOULD BE PRETTY
SIGNIFICANT...ESPECIALLY NEAR THE COAST.
HIGH TEMPS TUESDAY WILL BE RIGHT AROUND CLIMO...LOW 80S...AS STRONG
WAA IS COUNTERACTED BY CLOUD COVER AND SHOWERS...WHILE NIGHTTIME
MINS WILL BE HELD WELL ABOVE NORMAL...ONLY FALLING TO THE UPPER
60S/LOW 70S. WEDNESDAY WILL BE COOLER BEHIND THE FRONT...AROUND 80
FOR HIGHS AND NEAR 60 FOR LOWS AWAY FROM THE IMMEDIATE COAST.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 300 AM MONDAY...FRONT HOVERING JUST OFFSHORE MAY ALLOW FOR
CONTINUED SHOWERS NEAR THE COAST ON THURSDAY. FORECAST PROFILES DRY
OUT CONSIDERABLY HOWEVER...AND WILL DROP INHERITED CHC TO JUST SCHC
ON THE COAST...SILENT INLAND. BEST CHANCE WILL BE DURING THE EARLY
PART OF THE DAY BEFORE HIGH PRESSURE MORE FIRMLY RIDGES DOWN THE
COAST FORCING THE FRONT FURTHER OFFSHORE. OTHERWISE...THE EXTENDED
FEATURES DRY AND SEASONABLE WEATHER AS HIGH PRESSURE DOMINATES AT
THE SURFACE AND A LARGE UPPER TROUGH PERSISTS OVER THE EASTERN HALF
OF THE COUNTRY. ONLY FEATURE OF INTEREST IS A COLD FRONT WHICH WILL
TRY TO CROSS INTO THE AREA ON SATURDAY. WITH UPPER TROUGH RELOADING
ACROSS THE GREAT LAKES...MID LEVEL WINDS WILL REMAIN OUT OF THE WSW
WHICH WILL INHIBIT THIS FRONT FROM MAKING ANY NOTICEABLE IMPACT TO
THIS AREA...AND ANY COOLER AIR AND/OR PRECIP WILL BE DISPLACED NORTH
OF THE CWA.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
AS OF 06Z...PERIODS OF MVFR/IFR OVERNIGHT AND INTO THE EARLY MORNING
HOURS WITH VCSH/SCATTERED SHRA AND POTENTIAL BR/LOW CIGS INLAND.
FOR SEVERAL HRS AFTER DAYBREAK...EXPECT VFR/MVFR WITH BRIEF
PERIODS OF IFR DUE TO SHRA/BR. FOR THE AFTERNOON/EVENING VFR WITH
BRIEF PERIODS OF MVFR/IFR FROM CONVECTION.
SHRA AND VCSH WILL CONTINUE THROUGH THE OVERNIGHT HOURS THROUGH
MID-MORNING. LOOKING AT NE-E LIGHT WINDS OVERNIGHT WITH THE BEST
CHANCE FOR LOW CEILINGS/FOG ACROSS THE INLAND SITES BEFORE
SUNRISE. AFTER DAYBREAK...LINGERING MVFR/IFR FOG WILL DISSIPATE
AND CIGS WILL LIFT GIVING WAY TO VFR. LOW TO MID SCT/BKN CLOUDS
WILL CONTINUE THROUGHOUT THE DAY WITH A CHANCE FOR MVFR FROM
SHRA/TSRA ACROSS THE AREA. EAST-SOUTHEAST WINDS WILL INCREASE TO
AOB 10 KTS BY THE AFTERNOON HOURS...BECOMING SOUTHERLY ALONG THE
COAST WITH GUSTS 15 TO 20 KTS. INTO THE EVENING HOURS...SHRA/TSRA
WILL GRADUALLY QUIET DOWN...EXCEPT FOR CONVECTIVE ACTIVITY OFF THE
ATL WATERS THAT COULD MOVE ONSHORE BY MIDNIGHT DUE TO A DEEPER
ONSHORE FLOW MATERIALIZING. SOUTHERLY WINDS TO INCREASE TO
SUSTAINED 10 KT BY MIDNIGHT...ESPECIALLY AT THE COASTAL TERMS.
THE EXTENDED OUTLOOK...SHRA/TSRA ON TUESDAY WITH MODERATE
CONFIDENCE FOR INTERMITTENT IFR CONDITIONS. CONVECTION WILL
CONTINUE INTO WEDNESDAY WITH IMPROVING CONDITIONS THURSDAY INTO
SATURDAY.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 350 AM MONDAY...SCA RAISED FOR ALL ILM WATERS FOR LATE
TONIGHT. SE-S WINDS 10 KT...WILL BECOME SOUTHERLY 10-15 KT BY THIS
AFTERNOON...AND FURTHER INCREASE TO 15 TO 20 KT TONIGHT. THIS IN
RESPONSE TO AN ORGANIZING SFC PRESSURE PATTERN...AND INCREASING
GRADIENT DEVELOPING AHEAD OF THE APPROACH OF A SURFACE COLD FRONT
FROM THE WEST. SIGNIFICANT SEAS WILL INITIALLY COMMENCE AT 2 TO
4 FT...MAINLY COMPRISED OF A 10-12 SECOND SE SWELL. WITH
INCREASING WINDS LATER TODAY AND TONIGHT...LOCALLY PRODUCED WIND
DRIVEN WAVES AT 4 TO 7 SECOND AVERAGE PERIODS WILL BECOME MORE
DOMINANT. AT THIS POINT...SWAN ADVERTIZES SIG. SEAS REACHING 4 TO
6 FT ACROSS ALL WATERS JUST PRIOR TO DAYBREAK TUE...HENCE THE
RAISING OF A SCA. WIND FIELDS JUST OFF THE DECK ARE PROGGED TO
REACH 40 KT AFTER MIDNIGHT TONIGHT. AS A RESULT...CONVECTION THAT
TRAVERSES THE ILM WATERS WILL TAP INTO THESE HIER WINDS AND
POTENTIALLY DROP THEM TO THE OCEAN SFC AS WIND GUSTS 35 KT OR
GREATER. FAVORABLE LOW LEVEL WIND SHEAR AND HODOGRAPH WILL AID
ISOLATED WATERSPOUT POSSIBILITIES...MAINLY BETWEEN MIDNIGHT AND UP
TO SEVERAL HOURS AFTER DAYBREAK TUE.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM MONDAY...STRONG SOUTHERLY WINDS AHEAD OF A POTENT COLD
FRONT WILL CREATE SMALL CRAFT ADVISORY CONDITIONS THROUGH MUCH OF
TUESDAY. WINDS OF 15-25 KTS WILL HELP BUILD SEAS TO 4-6 FT...HIGHEST
ACROSS THE NORTHERN WATERS. WAVES WILL BE FORMED BY A COMBINATION OF
A WEAK SE SWELL AND THE MORE DOMINANT 6 SEC SOUTHERLY WIND
WAVES...SO EXPECT RELATIVELY STEEP WAVE FACES THROUGH THE DAY.
ADDITIONALLY...STRONG THUNDERSTORMS ARE POSSIBLE AHEAD OF THE COLD
FRONT AS IT ADVANCES EASTWARD THROUGH THE EVENING. THESE STORMS
COULD PRODUCE MUCH STRONGER WIND GUSTS AND TORRENTIAL RAINFALL...AS
WELL AS LOCALLY ENHANCED WAVE HEIGHTS.
WINDS TURN WESTERLY EARLY WEDNESDAY WITH THE FRONT AND THEN BECOME
LIGHT AND VARIABLE AS THE BOUNDARY WAVERS OVER THE COASTAL WATERS.
BY LATE WEDNESDAY WINDS WILL BECOME NE...BUT REMAIN LESS THAN 10
KTS. SEAS FALL QUICKLY DURING THE DAY...FROM 3-5 FT EARLY TO 2-3 FT
LATE...THANKS TO THE EASING WIND SPEEDS.
LONG TERM /THURSDAY THROUGH FRIDAY/...
AS OF 300 AM MONDAY...HIGH PRESSURE RIDGES DOWN THE COAST THURSDAY
BEFORE DRIFTING OFFSHORE FRIDAY. NE WINDS OF AROUND 10 KTS PERSIST
MUCH OF THURSDAY BEFORE THE GRADIENT RELAXES...ALLOWING WINDS TO
BECOME LIGHT AND VARIABLE FRIDAY...BEFORE FINALLY TURNING TO THE SE
AT THE END OF THE PERIOD. WAVE GUIDANCE SHOWS SEVERAL DIFFERENT WAVE
GROUPS PRESENT IN THE SPECTRUM THROUGH THE EXTENDED...WITH NO GROUP
BECOMING DOMINANT. WITHOUT ANY MEANINGFUL SWELL OR PRESSURE
GRADIENT...SEAS WILL BE 1-3 FT THURSDAY...AND ONLY 1-2 FT ON FRIDAY.
&&
.TIDES/COASTAL FLOODING...
AS OF 350 AM MONDAY...BETWEEN 10 AM AND NOON TODAY...PROGGED MDL
WILMINGTON TIDE GAGE FORECASTS INDICATE A THREAT FOR GAGE READINGS
ABOVE THE 5.50 FT MLLW COASTAL FLOOD ADVISORY THRESHOLD BETWEEN 10
AM AND NOON TODAY. A PEAK OF 5.60 FT MLLW IS FORECAST AROUND 11
AM. THE PRONE LOCATIONS TO THIS TYPE OF SHALLOW FLOODING WILL
INCLUDE AREAS BORDERING ALONG THE CAPE FEAR RIVER SUCH AS WATER
STREET OF DOWNTOWN WILMINGTON... ROADWAYS LEADING TO AND FROM THE
USS NORTH CAROLINA BATTLESHIP... AND CANAL ROAD IN CAROLINA BEACH.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...COASTAL FLOOD ADVISORY FROM 10 AM THIS MORNING TO NOON EDT
TODAY FOR NCZ107-108.
MARINE...SMALL CRAFT ADVISORY FROM 5 AM TUESDAY TO 5 AM EDT WEDNESDAY
FOR AMZ250-252-254-256.
&&
$$
SYNOPSIS...JDW
NEAR TERM...DCH
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...DCH/SGL
TIDES/COASTAL FLOODING...DCH
AREA FORECAST DISCUSSION
NWS NORMAN OK
1227 AM CDT MON SEP 17 2012
.AVIATION...
SKIES HAVE CLEARED ACROSS THE WEST WITH SOME MID/HIGH CLOUDS
LINGERING OVER EASTERN SITES. NAM AND HRRR SHOWING SOME DEVELOPMENT
OF LOW CLOUDS OVERNIGHT. GIVEN THAT LOW LEVELS REMAIN RELATIVELY
MOIST AND WITH A LIGHT SOUTHERLY FLOW EXPECTED TO CONTINUE WILL GO
WITH REDEVELOPMENT OF MVFR/IFR CIGS LATER TONIGHT. CLOUDS SHOULD
SCATTER OUT DURING THE MORNING GIVING WAY TO VFR CONDITIONS BY
MIDDAY. COLD FRONT IS EXPECTED TO MOVE ACROSS THE AREA DURING THE
DAY MONDAY SHIFTING WINDS BACK TO THE NORTH.
&&
.PREV DISCUSSION... /ISSUED 1015 PM CDT SUN SEP 16 2012/
.UPDATE...
NO SIGNIFICANT CHANGES TO THE FORECAST... ALTHOUGH HAVE UPDATED
THE CLOUD COVER SOMEWHAT. THE CURRENT OVERCAST IS ONLY SLOWLY
MOVING EAST. HRRR AND SOME OF THE NEW MOS GUIDANCE IS SUGGESTING
THAT STRATUS WILL REDEVELOP OVERNIGHT... MAINLY IN THE SOUTHEAST
THIRD OR SO OF THE AREA... BUT ALSO ACROSS THE WEST WHERE SKIES
ARE CURRENTLY CLEAR. IT REMAINS TO BE SEEN HOW WIDESPREAD IT WILL
BECOME... BUT WITH RELATIVELY LOW DEWPOINT DEPRESSIONS AND SOME
LOW-LEVEL MOISTURE ADVECTION WITH THE SOUTH WINDS... DO BELIEVE
THAT WE WILL SEE SOME STRATUS.
&&
.PREV DISCUSSION... /ISSUED 620 PM CDT SUN SEP 16 2012/
AVIATION...
MID/HIGH CLOUDS OVER EASTERN PART OF THE AREA SHOULD CONTINUE TO
GRADUALLY CLEAR FROM THE NW. COULD BE SOME PATCHY MVFR CONDITIONS
OVERNIGHT...MAINLY EAST BUT VFR CONDITIONS EXPECTED AREAWIDE BY
MONDAY MORNING. FRONT EXPECTED TO MOVE INTO NW OK MONDAY MORNING
AND THE PROGRESS THROUGH MOST SITES BY THE END OF THE PERIOD.
PRECIP CHANCES WITH THE FRONT TOO LOW TO INCLUDE IN TAFS ATTM.
PREV DISCUSSION... /ISSUED 224 PM CDT SUN SEP 16 2012/
DISCUSSION...
STILL DEALING WITH SLOW MOVING TROUGH ACROSS THE SOUTHERN PLAINS
AND TEXAS AND ASSOCIATED CLOUD COVER AND LIGHT RAIN ACROSS
SOUTHEAST OKLAHOMA. WILL KEEP SOME LOW POPS ACROSS THE SOUTHEAST
TONIGHT. MAY SEE SOME PATCHY FOG AGAIN LATE TONIGHT ACROSS PARTS
OF CENTRAL AND SOUTHEAST SECTIONS OF OKLAHOMA... BUT FOR NOW WILL
LEAVE OUT OF THE FORECAST.
MOST AREAS SHOULD SEE SUN ON MONDAY WITH WARMER TEMPS AHEAD OF
COLD FRONT WHICH WILL ENTER NORTHEAST OKLAHOMA BY LATE
MORNING/MIDDAY AND THEN MOVE QUICKLY SOUTH INTO NORTH TEXAS DURING
THE AFTN. CONT TO SEE VERY WEAK CONVERGENCE ALONG THIS FRONT...
HOWEVER MODELS STILL SHOW MODEST INSTABILITY AND MID-LEVEL LAPSE
RATES TO INITIATE STORMS. ALTHOUGH STILL APPEARS CHANCES WILL
REMAIN RATHER LOW WILL KEEP LOW POPS MONDAY AFTN AND MONDAY NIGHT
ON OUTSIDE CHANCE OF A STORM OR TWO ALONG AND BEHIND FRONT.
MILD MIDDLE OF THE WEEK WITH WARMING TREND BY LATE IN THE WEEK.
SOUTHERN PLAINS REMAIN IN NORTHWEST FLOW THROUGH NEXT WEEKEND.
HOWEVER MEDIUM RANGE MODELS CONT TO DISAGREE ON TIMING AND
STRENGTH OF SFC BOUNDARIES LATE THIS WEEK INTO NEXT WEEKEND. WILL
NOT MAKE ANY MAJOR CHANGES TO LATTER PART OF FORECAST AT THIS TIME
AS CONFIDENCE IN ANY PARTICULAR SCENARIO IS NOT HIGH. ESPECIALLY
WITH REGARDS TO PRECIP CHANCES.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 60 85 53 77 / 0 20 20 0
HOBART OK 58 86 52 76 / 0 20 20 0
WICHITA FALLS TX 61 88 57 80 / 0 10 20 10
GAGE OK 52 82 46 78 / 0 10 10 0
PONCA CITY OK 59 80 49 75 / 0 20 10 0
DURANT OK 63 85 58 78 / 20 10 20 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
319 PM CDT MON SEP 17 2012
DISCUSSION...CONTINUING TO SEE DEEPENING LOWER PRESSURE ALONG THE
GULF COAST THIS AFTERNOON. CURRENTLY...THIS FEATURE IS VERY CLOSE
TO THE COASTLINE OF LOUISIANA. MEANWHILE...UPPER LEVEL TROUGH OVER
EASTERN TX WITH THE ASSOCIATED AXIS EXTENDING NORTH NORTHEASTWARD.
STRONG PVA WILL CONTINUE TO RESIDE ALONG THE NE TRACK OF THE SFC
LOW AND THIS WILL RESULT IN FURTHER STRENGTHENING THROUGH TONIGHT.
IN ADVANCE OF THE APPROACHING SFC LOW...AN AREA OF INCREASING
INSTABILITY IS MOVING NORTHWARD FROM MS AND AL. THIS WILL CONTINUE
TO ADD TO THE FLOOD THREAT WITH THE POTENTIAL OF FLASH FLOODING.
LATEST HRRR RUN SHOWS SCATTERED TO BROKEN HEAVIER SHOWERS AND TSTMS
OCCURRING ACROSS OUR SOUTHERN AREAS BETWEEN NOW AND THIS EVENING.
THEN...LATER TONIGHT...ANOTHER ROUND OF WIDESPREAD RAINFALL WILL
MOVE ACROSS THE AREA. THIS ONSLAUGHT OF WIDESPREAD RAINFALL WILL BE
IN CONJUNCTION WITH THE STRENGTHENING SFC LOW THAT WILL BE MOVING
CLOSER. IN FACT...THE SFC LOW SHOULD REACH MIDDLE TN AROUND OR
SHORTLY AFTER MIDNIGHT TONIGHT. THE HEAVIEST RAINFALL SHOULD BEGIN
TO EXIT OUR PLATEAU AREA SHORTLY AFTER MIDNIGHT.
HOWEVER...RAINFALL...THOUGH LIGHTER...SHOULD CONTINUE INTO TUESDAY
MORNING.
ADDITIONAL PREDICTED RAINFALL AMOUNTS FROM 4 PM THROUGH TONIGHT WILL
INCLUDE 3 TO 5 INCHES ALONG THE CUMBERLAND PLATEAU...2 TO 3 INCHES
FOR THE CENTRAL THIRD OF THE MID STATE...AND AROUND 1 INCH ACROSS
THE WEST. LOCALLY HIGHER AMOUNTS WILL ALSO BE POSSIBLE. THE
PRECIPITATION SHOULD TAPER OFF TO LIGHT RAIN AND/OR DRIZZLE AFTER
SUNRISE ON TUESDAY.
OTHERWISE...COOLER AND DRIER AIR WILL BEGIN MOVING IN BY TUESDAY
AFTERNOON. CLOUDS SHOULD BEGIN TO DECREASE BY AFTERNOON ACROSS
WESTERN AREAS. THE COOL SPELL WILL CONTINUE THROUGH THURSDAY. AS THE
SFC HIGH REACHES MIDDLE TN ON WEDNESDAY AND THURSDAY
MORNING...OVERNIGHT LOW TEMPERATURES WILL FALL INTO THE 40S.
IN THE EXT FCST...A BRIEF WARMUP WILL OCCUR ON FRIDAY IN ADVANCE OF
THE NEXT FRONTAL SYSTEM. AFTER A 20-30 PERCENT CHANCE OF SHOWERS FOR
FRI NT AND SATURDAY...IT WILL AGAIN TURN COOL WITH LOWS IN THE 40S
AND HIGHS IN THE LOWER 70S FOR SUNDAY AND MONDAY.
.PRELIMINARY POINT TEMPS/POPS...
NASHVILLE 63 70 46 71 / 90 50 10 05
CLARKSVILLE 61 69 43 72 / 80 50 10 05
CROSSVILLE 62 69 46 67 / 100 80 10 10
COLUMBIA 64 71 46 72 / 90 50 10 05
LAWRENCEBURG 63 71 46 72 / 90 60 10 05
WAVERLY 62 70 43 72 / 80 50 10 05
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH THROUGH TUESDAY MORNING FOR TNZ008>011-027>034-
058>066-075-077>080-093>095.
&&
$$
21
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
831 PM CDT TUE SEP 18 2012
.SHORT TERM...TONIGHT INTO TOMORROW MORNING
831 PM CDT TUE SEP 18 2012
THE MAIN SHORT TERM CONCERN IS WITH THE POTENTIAL FOR FROST
OVERNIGHT...PARTICULARLY IN WESTERN WISCONSIN WHERE SKIES WILL BE
CLEAR AND WINDS WILL BE LIGHT FOR A BRIEF PERIOD LATE THIS EVENING
AND EARLY TOMORROW MORNING. SOME OF THE TYPICAL LOW SPOTS THAT RUN
FROM BLACK RIVER FALLS DOWN TO SPARTA AND ACROSS TO VOLK FIELD
FROM JACKSON COUNTY TO JUNEAU COUNTY HAVE ALREADY DROPPED INTO THE
37-40 DEGREE RANGE...BUT OTHER OBSERVATIONS IN SLIGHTLY HIGHER
TERRAIN ARE STILL IN THE 40-50 DEGREE RANGE. CLOUD COVER WILL BE
ON THE INCREASE THROUGH THE NIGHT FROM THE WEST ALONG THE WARM AIR
ADVECTION WING AS WELL AS FROM THE NORTH AS THE MID LEVEL TROUGH
DIVES INTO THE REGION. THE 18.23Z RAP AND 18.18Z NAM/GFS ALL SHOW
THIS BROKEN TO OVERCAST CLOUD COVER MOVING IN ACROSS WESTERN
WISCONSIN AROUND 6Z...WHICH WOULD HELP KEEP TEMPERATURES UP ONCE
IT MOVES IN. WHILE TEMPERATURES WILL DIP IN THESE LOW LYING
LOCATIONS THIS EVENING AND FROST WILL LIKELY FORM IN THEM...IT
WILL LIKELY NOT BE WIDESPREAD ENOUGH ACROSS THIS REGION TO ISSUE
AN ADVISORY FOR OVERNIGHT. ON TOP OF THAT...THE WINDOW FOR
TEMPERATURES TO BE COLD ENOUGH AND WINDS TO REMAIN LIGHT TO
PRODUCE FROST IS SHORT ENOUGH THAT THE IMPACTS FROM A TRUE FROST
MAY NOT OCCUR. ALL OF THIS LEADS TO CONFIDENCE NOT BEING HIGH
ENOUGH TO PULL THE TRIGGER ON AN ADVISORY.
.LONG TERM...SATURDAY THROUGH TUESDAY
230 PM CDT TUE SEP 18 2012
MODELS REMAIN VERY PERSISTENT ON HAVING THE DEEP UPPER LEVEL TROUGH
IMPACT THE AREA...WITH THIS DIRTY CYCLONIC FLOW SPITTING A SHORTWAVE
OR TWO ACROSS THE REGION. SOME DIFFERENCES IN TIMING AND POSITIONING
OF THE BITS OF ENERGY...BUT ALL POINT TO A CONTINUATION OF THE BELOW
NORMAL TEMPERATURES.
THE MODELS DO SUGGEST THAT THE TROUGH WILL FINALLY PUSH EAST FOR THE
BEGINNING OF NEXT WEEK. THE REGION WILL STILL BE UNDER NORTHWEST
FLOW...BUT TEMPERATURES SHOULD REBOUND CLOSER TO THE SEASONABLE
NORMALS.
&&
.AVIATION...TONIGHT AND WEDNESDAY
641 PM CDT TUE SEP 18 2012
ALTHOUGH VFR CONDITIONS ARE EXPECTED AT KRST/KLSE DURING THE NEXT 24
HOURS...FORECAST CONCERNS ARE FOCUSED ON A WARM AND COLD FRONTAL
PASSAGE...ALONG WITH THE CHANCE FOR SHOWERS/STORMS WEDNESDAY
AFTERNOON. AS OF 00Z...A NORTH/SOUTH ORIENTED WARM FRONT WAS ACROSS
CENTRAL MINNESOTA AND IOWA...RIGHT ALONG THE I-35 CORRIDOR...MAKING
A SLOW BUT STEADY PROGRESS EASTWARD. MID LEVEL CLOUDS WERE
ASSOCIATED WITH THIS FRONT...WHICH IS EXPECTED TO PASS KRST AROUND
03Z AND KLSE BY 06Z. THEN A STRONG 925 MB LOW-LEVEL JET SETS UP
ACROSS THE AREA OVERNIGHT SUCH THAT BY 09Z LATEST FORECAST SOUNDINGS
DEPICT 925 MB WINDS AROUND 50 KTS AT KRST AND 45 KTS AT
KLSE...SUFFICIENT FOR LLWS GIVEN SURFACE WINDS AROUND 12 KTS. AFTER
SUNRISE...THE LLJ MIXES OUT AND BY 14Z LLWS CONDITIONS SHOULD
SUBSIDE AT KRST/KLSE.
A COLD FRONT WILL SWEEP THROUGH THE AREA WEDNESDAY AFTERNOON AND AHEAD
OF THIS FRONT...A VERY TIGHT PRESSURE GRADIENT ALONG WITH DEEP
MIXING WILL RESULT IN GUSTS AROUND 30 KTS AT BOTH KRST/KLSE. THE
FRONT IS EXPECTED TO PASS KRST AROUND 21Z...CLOSER TO 23Z AT KLSE.
REGARDING SHOWER/THUNDERSTORM CHANCES...THE BEST FORCING AND
INSTABILITY LOOK TO MISS KRST...BUT COULD BE CLOSE ENOUGH AT KLSE.
CONFIDENCE ON A THUNDERSTORM IMPACTING THE AIRPORT IS LOW AT THIS
TIME...SO WILL INTRODUCE JUST A VICINITY SHOWER MENTION FOR NOW.
BROKEN MID LEVEL CLOUDS WILL ACCOMPANY THIS FRONTAL PASSAGE AS
WELL.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
230 PM CDT TUE SEP 18 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM....RIECK
AVIATION...ZT
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1212 PM CDT MON SEP 17 2012
.UPDATE...MAIN CONCERN THIS UPDATE WERE WX AND POP GRIDS. RADAR
MOSAIC SHOWS A SWATH OF PRECIP STRETCHING FROM NORTHERN WISCONSIN
TO SOUTHEAST MN AND CENTRAL IA. THIS FEATURE ANTICIPATED TO
PROVIDE THE BULK OF THE PRECIPITATION TODAY...AND IS ASSOCIATED
WITH LOW LEVEL FRONOTOGENESIS. SURFACE FRONT IS SEEN ALONG OUR FAR
NW PORTION OF THE FORECAST AREA AT THE MOMENT...AND IT SHOULD EXIT
THE FAR SE BETWEEN 21 AND 00 UTC.
WX AND POPS WERE PUSHED BACK SOMEWHAT THIS AFTERNOON. HRRR AND
NAM12 MODEL REFLECTIVITY FIELDS HAVE BEEN TRENDING WELL WITH RADAR
MEASUREMENTS. GIVEN THIS AND LATEST RADAR TRENDS...EXPECT AREA OF
SHOWERS AND ISOLATED THUNDERSTORMS TO ENTER SOUTH CENTRAL WI
BETWEEN 2 AND 4 PM CDT...AND SOUTHEAST WI BETWEEN 4 PM AND 6 PM.
KEPT AN AREA OF SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ALONG
AND AHEAD OF THE FRONT AS WELL EARLIER THIS AFTERNOON.
THE AREA OF RAIN SHOWERS SHOULD CORRESPOND WELL WITH WHERE THE
BETTER LOW LEVEL FRONTOGENETIC RESPONSE IS SEEN. THIS WILL BE IN
THE LOWER LEVELS OF THE ATMOSPHERE AT 18 AND 00 UTC...LOOKING AT
1000-850 AND 850-700 HPA LAYERS.
&&
.AVIATION/18Z TAFS/...COLD FRONT WILL PUSH SOUTHEAST ACROSS TAF
SITES THROUGH 22Z THIS AFTERNOON...WITH QUICK WIND SHIFT TO THE
NORTHWEST ACCOMPANYING THE FRONT. NORTHWEST WINDS WILL BE GUSTY
BEHIND THE FRONT...GUSTING IN THE 20 TO 25 KNOT RANGE UNTIL EARLY
THIS EVENING.
A BAND OF SHOWERS IS EXPECTED TO SHIFT THROUGH THE AREA BEHIND
THE FRONT LATER THIS AFTERNOON...LASTING INTO EARLY THIS EVENING
ACROSS THE EASTERN TAF SITES. ISOLATED THUNDERSTORMS MAY FORM
ALONG THE COLD FRONT AS WELL...BUT LEFT MENTION OUT OF TAFS FOR
NOW. MVFR CEILINGS ARE POSSIBLE WITH THE BAND OF SHOWERS...THOUGH
SHOULD ALTERNATE BETWEEN MVFR AND VFR CATEGORY.
NORTHWEST WINDS WILL REMAIN MODERATE TONIGHT INTO TUESDAY...WITH
GUSTS UP TO 20 KNOTS POSSIBLE TUESDAY AFTERNOON. VFR CEILINGS
SHOULD GRADUALLY MIX OUT AS THE NIGHT GOES ON...WITH DRIER AIR
WORKING INTO THE REGION.
UNSTABLE CONDITIONS TUESDAY AFTERNOON SHOULD ALLOW FOR SCATTERED
TO BROKEN CUMULUS CLOUDS TO DEVELOP...WITH A FEW SHOWERS POSSIBLE.
LEFT SHOWER MENTION OUT OF TAFS FOR NOW DUE TO UNCERTAINTY WITH
AREAL COVERAGE.
&&
.MARINE...SMALL CRAFT ADVISORY GOES INTO EFFECT FOR THE NEARSHORE
WATERS AT 21Z THIS AFTERNOON...LASTING THROUGH 00Z WEDNESDAY.
TIGHT PRESSURE GRADIENT DEVELOPS BEHIND THE COLD FRONT LATE THIS
AFTERNOON AND TONIGHT...SLOWLY WEAKENING ON TUESDAY. THIS SHOULD
ALLOW FOR GUSTY NORTHWEST WINDS TO 25 KNOTS DURING THIS TIME.
SUBSEQUENT HIGH WAVES OF 3 TO 6 FEET SHOULD DEVELOP TOWARD THE
OPEN WATERS LATER TONIGHT INTO TUESDAY...BEFORE SUBSIDING LATE ON
TUESDAY.
&&
.PREV DISCUSSION... /ISSUED 334 AM CDT MON SEP 17 2012/
SHORT TERM...
TODAY AND TONIGHT...CONFIDENCE - MEDIUM.
MID-LEVEL CLOUDS INCREASING AHEAD OF APPROACHING SFC COLD
FRONT...CURRENTLY EXTENDING FROM NORTHEAST WI TO NEAR KLSE. CLOUDS
AN INDICATOR OF INCREASING LOW-MID LEVEL RH IN OUR AREA AS GOES
SOUNDER MEASURED PRECIPITABLE WATER VALUES OVER AN INCH UPSTREAM IN
THE NORTHERN PLAINS. EXPC CLOUDS TO CONTINUE INCREASING EARLY THIS
MRNG ACROSS THE AREA. A FEW SHOWERS POSSIBLE EARLY IN VCNTY OF FRONT
BUT BETTER CHANCE LATER THIS MRNG WITH BEST CHANCE THIS AFTERNOON.
GFS AND ECMWF SHOWING BEST RUN TO RUN CONTINUITY WITH MID-LEVEL
FEATURES THIS AFTN AND EVE. INITIALLY THOUGHT I WOULD NEED TO LOWER
POPS IN SOME AREAS THIS AFTN AS LOW-MID LEVEL DEFORMATION ASSOCIATED
WITH SHORT WAVE INDICATED TO WEAKEN AS IT PASSES ACROSS SRN WI.
HOWEVER WITH MID-LEVEL WAVE EXPECTED TO SHARPEN AS IT PASSES ACROSS
SOUTHERN WI...AND IMPRESSIVE LAYER FN VECTOR RESPONSE TO
FRONTOGENETICAL FORCING...WL CONTINUE HIGH POPS THIS AFTN. LAYER
Q-VECTOR CONVERGENCE TIED TO SURGE OF HIGHER LAYER RH PASSES THRU
SRN WI DURING THE AFTN AS WELL...WHICH IS ALSO TIED TO PERIOD OF
ENHANCED FORCING FROM RIGHT ENTRANCE REGION OF 3H JET. BETTER
CHANCE FOR MORE PROLONGED SHOWERS IN NORTH CLOSER TO
DEFORMATION...AND IN THE SOUTHEAST WHERE MUCAPES MAY CLIMB TO OVER
500 J/KG ALONG CDFNT. WL CONTINUE TO MENTION SMALL T THREAT TODAY.
SHWRS WL END FROM WEST TO EAST ACROSS SRN WI FROM MID-AFTN THRU THE
EVE AS COOLER...DRIER AIR RUSHES IN FROM THE NORTH AND DEFORMATION
SLIDES OFF TO THE EAST. PARTIAL CLEARING AND CHILLY AIR WL ALLOW
TEMPS TO FALL INTO THE UPPER 30S IN THE WEST TONIGHT.
TUESDAY...FORECAST CONFIDENCE MEDIUM.
WEAK VORTICITY WITHIN THE AXIS OF THE 500MB TROUGH AND THE 850MB
THERMAL TROUGH WILL BE MOVING ACROSS WISCONSIN ON TUESDAY...MOST
LIKELY IN THE MORNING. GFS AND NAM MODEL SOUNDINGS STILL LOOK
CONDUCIVE FOR DIURNAL CUMULUS CLOUDS AND SOME ISOLATED SHOWERS OR
SPRINKLES...EVEN THOUGH THEY ARE NOT SHOWING MUCH/ANY QPF. THE 00Z
ECMWF CAME IN WITH 0.01 TO 0.03 ACROSS MUCH OF WI. COMPARISON OF
MODEL CU RULE INDICATES WIDESPREAD CLOUDS QUICKLY DEVELOPING IN THE
MORNING AND THEN DISSIPATING FROM WEST TO EAST EARLY IN THE
AFTERNOON AS THE VERY DRY AIR WORKS ITS WAY IN.
KEPT A SMALL CHANCE FOR LIGHT SHOWERS OR SPRINKLES IN THE FORECAST
ON TUESDAY. MAX TEMPS WILL ONLY BE IN THE UPPER 50S TO AROUND 60
WITH 925MB TEMPS AROUND 8C.
TUESDAY NIGHT...FORECAST CONFIDENCE HIGH.
CLEAR SKIES AND VERY COOL TEMPERATURES WILL SETTLE INTO SOUTHERN WI
ON TUESDAY NIGHT AS A RIDGE OF HIGH PRESSURE BRIEFLY MOVES ACROSS
THE REGION. THE NAM IS MORE BULLISH WITH WARM AIR ADVECTION IN
RETURN FLOW AROUND THE HIGH TUE NIGHT WHILE THE OTHER MODELS KEEP
925MB TEMPS AROUND 8C AND 850MB TEMPS AROUND 1C TO 2C. MIN TEMPS
SHOULD DROP INTO THE MID 30S INLAND.
CONTINUED MENTION OF PATCHY FROST IN THE FORECAST FOR MUCH OF THE
FORECAST AREA BUT KEEP IN MIND THAT PATCHY IS THE KEY WORD. WITH
SOIL TEMPS IN THE 60S TO LOW 70S AND POSSIBLY SOME HIGH CLOUDS
STREAMING IN LATE WITH THE WARM AIR ADVECTION KEEPING THE AREA
SLIGHTLY WARMER...ESPECIALLY IN THE WEST...THERE IS A LIMITED
POTENTIAL FOR FROST.
LONG TERM...
WEDNESDAY AND THURSDAY...FORECAST CONFIDENCE MEDIUM.
ANOTHER UPPER TROUGH WITH A DECENT VORT MAX WILL CROSS WI WED
AFTERNOON/EVENING AND BRING ANOTHER CHANCE FOR SHOWERS. SHOWERS
WOULD BE SCATTERED IN NATURE AND PRECIP AMOUNTS WILL BE LIGHT.
TIGHT PRESSURE GRADIENT BETWEEN EXITING HIGH PRESSURE AND THE
SURFACE TROUGH APPROACHING WILL CREATE BREEZY SOUTH TO SOUTHWEST
WINDS WED AFTERNOON. WIND GUSTS OF 25 TO 30 MPH WILL BE POSSIBLE.
THE WINDS WILL ALSO USHER IN WARMER AIR...WITH HIGHS RANGING FROM
AROUND 70 IN THE WESTERN FORECAST AREA TO THE UPPER 60S EAST.
THE SURFACE FRONT WILL CLEAR SOUTHEAST WI BY 12Z THU AND ANY PRECIP
SHOULD BE OUT OF THE AREA BY THEN. NOT SURE WHAT TO EXPECT FOR CLOUD
COVER ON THURSDAY...EXCEPT IT LOOKS LIKE AT LEAST HIGH CLOUDS WILL
BE STREAMING OVER THE REGION DUE TO THE UPPER JET OVER NORTHERN
WISCONSIN. LOW LEVELS LOOK DRY AT THIS TIME.
FRIDAY THROUGH SUNDAY...FORECAST CONFIDENCE MEDIUM.
SEVERAL 500MB TROUGHS ASSOCIATED WITH DEEP LOW PRESSURE OVER HUDSON
BAY WILL SWING ACROSS THE UPPER GREAT LAKES REGION FOR MUCH OF THE
WEEKEND. MODELS SHOW THAT UPPER TROUGH SHIFTING EAST DURING THE DAY
ON SUNDAY. THIS MEANS COOL TEMPERATURES...PLENTY OF CLOUDS DURING
THE DAYTIME...A BRISK NORTHWEST BREEZE...AND A SMALL CHANCE OF
SHOWERS OR SPRINKLES FOR FRIDAY AND SATURDAY. THE SUN SHOULD BE OUT
MORE ON SUNDAY AS THE TROUGH MOVES AWAY.
AVIATION/12Z TAFS/...MID-LEVEL CLOUDS FILLING IN AHEAD OF
APPROACHING SFC FRONT OVER CENTRAL WI. EXPC CLOUDS TO CONTINUE TO
INCREASE EARLY THIS MRNG. THESE INCREASING CLOUDS AN INDICATOR OF
INCREASING LOW-MID LEVEL RH AND LOW LEVEL CONVERGENCE. GOES SOUNDER
INDICATED UPSTREAM PRECIPITABLE WATER VALUES OVER 1.0 INCH. HENCE
NEED TO WATCH FOR SHRA DEVELOPMENT AND ISOLD T ALONG PASSING FRONT.
EXPECT A SWATH OF SHRA AND ISOLD T TO SWEEP ACROSS TAF SITES THIS
AFTN AND EARLY EVE WHEN STRONGEST FORCING ASSOCD WITH MID-LEVEL
SHORT WAVE MOVES THRU. MAY BE A PERIOD OF MVFR CIGS AND VSBYS WITH
SHRA AND LOW LEVEL COLD AIR ADVECTION THIS AFTN AND EVENING BEFORE
CLEARING.
MARINE...COLD FRONT CUTTING ACROSS WI WL SWEEP ACROSS THE LAKE MI
NEARSHORE WATERS FROM LATE THIS MRNG THRU MID-LATE AFTN. SOUTHWEST
WINDS WL BRIEFLY TURN TO THE NORTH BUT WL BE PREDOMINANTLY NORTHWEST
AFT FROPA WITH A FEW HIGHER GUSTS IMMEDIATELY AFT FROPA. STRONG LOW
LEVEL COLD AIR ADVECTION TONIGHT WILL CREATE STEEP LOW LEVEL LAPSE
RATES OVER THE NEAR SHORE WATERS. THE UNSTABLE CONDITIONS ALONG WITH
A TIGHTENING PRESSURE GRADIENT SHOULD CAUSE WIND GUSTS TO REACH
SMALL CRAFT ADVY LEVELS...POSSIBLY LATER THIS AFTN...BUT MOSTLY TNGT
WHEN THE MOST UNSTABLE CONDITIONS ARE ANTICIPATED. WILL ISSUE SMALL
CRAFT ADVY FROM 21Z TODAY THRU 00Z/WED. STRONGEST WINDS GUSTS WL
LIKELY BE TNGT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 7 PM CDT
TUESDAY FOR LMZ643>646.
&&
$$
UPDATE...ET/WOOD
TODAY/TONIGHT AND AVIATION/MARINE...MBK
TUESDAY THROUGH SUNDAY...MRC
AREA FORECAST DISCUSSION
NWS TAUNTON MA
409 AM EDT WED SEP 19 2012
.SYNOPSIS...
A COLD FRONT WILL PUSH THROUGH THE AREA THIS MORNING WITH RAIN
COMING TO AN END AND SKIES GRADUALLY CLEARING. HIGH PRESSURE WILL
THEN BUILD OVER THE AREA THROUGH THE LATTER PART OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
TWO WEAKENING LLJ/S ARE MOVING THROUGH ERN PORTIONS OF THE FA THIS
MORNING. THE FIRST IS ASSOCIATED WITH A WEAK LOW-TOPPED CONVECTIVE
LINE WHICH IS JUST MAKING IT TO CAPE COD AND THE ISLANDS THIS
HOUR. THIS WILL CONTINUE TO PUSH TO THE E AND WILL LIKELY BE
OFFSHORE BY SUNRISE. THE SECOND LLJ IS JUST NOW MOVING INTO THE
SRN COASTAL WATERS AND THE SE COASTAL PLAIN OF RI/MA. WHILE WINDS
ARE GENERALLY WEAKER WITH THIS LLJ...THERE IS ENOUGH MOISTURE WITH
IT THAT IT WILL ALLOW RAINFALL TO LINGER OVER PORTIONS OF SE MA/RI
THROUGH THE MID MORNING TIMEFRAME.
IN ANY CASE A COLD FRONT IS ALREADY MAKING ITS WAY THROUGH CENTRAL
MA ASSOCIATED WITH A TILTING KICKER TROF MOVING INTO SRN NEW
ENGLAND PER LATEST WV IMG. THIS WILL USHER IN SOME COOLER/DRIER
AIR AND PUSH THE RAIN BANDS OFFSHORE BY MID MORNING.
INDEED...DWPTS HAVE ALREADY DROPPED INTO THE LOW 50S IN BERKSHIRE
COUNTY AND WINDS HAVE SHIFTED TO THE NW IN THE CT VALLEY SO THE
DRY AIR IS ALREADY MOVING IN RAPIDLY. THIS WILL ALLOW FOR
GRADUALLY CLEARING SKIES AND IMPROVING CONDITIONS THROUGH THE
MORNING...WITH THE WHOLE AREA EXPECTING TO BE DRY WITH ONLY PARTLY
CLOUDY SKIES BY THE LATE AFTERNOON HOURS. HRRR HAS BEEN HANDLING
POPS RATHER WELL SO TIMING OF PRECIP END IS BASED ON ITS FORECAST.
IN TERMS OF THE WIND THREAT...WILL BE DROPPING WIND ADVISORY/HIGH
WIND WARNINGS FOR ALL AREAS SAVE FOR SE MA...ALTHOUGH THESE
WARNINGS TOO WILL BE ENDING SOON. THE STRONG HIGH PRES MOVING IN
WILL KEEP CONDITIONS COOL AND BREEZY DURING THE DAY TODAY...BUT
MOST WIND GUSTS SHOULD BE 30 MPH OR LESS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
TONIGHT...
HIGH PRES WILL CONTINUE TO BUILD OVER THE REGION FROM THE W WITH
CLEARING SKIES AND DECENT SUBSIDENCE INVERSION. BREEZY CONDITIONS
MAY LINGER INTO THE EVENING HOURS OVER EXTREME ERN PORTIONS OF THE
AREA...BUT EXPECT NEAR CALM CONDITIONS DURING THE LATE NIGHT HOURS
INLAND. THE COMBINATION OF THESE NEAR CALM CONDITIONS...CLEARING
SKIES AND H92 TEMPS DIPPING TO ABOUT +6C IN SRN NH BY LATE
NIGHT...RADIATIONAL COOLING WILL ALLOW TEMPS IN VALLEYS TO DIP
VERY CLOSE TO THE FREEZING MARK. WILL ISSUE A FROST ADVISORY FOR
HILLSBOROUGH COUNTY...WHERE VALLEYS HAVE BEST CHANCE OF DIPPING TO
NEAR FREEZING. THIS LINES UP WITH NEIGHBORS AS WELL. OTHERWISE...
TEMPS RANGING IN THE UPPER 30S TO MID 40S WILL BE LIKELY.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
* DUE TO ONGOING HIGH-IMPACT WEATHER OVERNIGHT LITTLE CHANGE *
* HAS BEEN MADE TO THE LONG TERM. *
HIGHLIGHTS...
* SLIGHTLY BELOW NORMAL TEMPS WED NIGHT AND THU
* MAINLY DRY THROUGH EARLY SAT OTHER THAN A SPOT SHOWER ON COAST
* A COLD FRONT MAY BRING A ROUND OF SHOWERS SOMETIME SAT NIGHT/SUN
* MAINLY DRY WEATHER LIKELY FOLLOWS NEXT MON-TUE
DETAILS...
WEDNESDAY NIGHT...
HIGH PRESSURE BUILDING ACROSS NEW ENGLAND BEHIND THE COLD FRONT WILL
BRING A DRY AND CHILLY NIGHT. LOW TEMPS WILL LIKELY BOTTOM OUT IN
THE MIDDLE TO UPPER 30S ACROSS THE NORMALLY COOLER OUTLYING
LOCATIONS OF SOUTHWEST NH/WESTERN MA...TO MAINLY THE 40S ELSEWHERE.
SOME FROST MAY OCCUR ACROSS OUR NORTHWEST INTERIOR ZONES...BUT ITS
UNCERTAIN WHETHER IT WILL BE WIDESPREAD ENOUGH TO WARRANT A FROST
ADVISORY. SOMETHING LATER SHIFTS WILL HAVE TO CONSIDER.
THURSDAY...
HIGH PRESSURE CENTERED OVER QUEBEC AND NORTHERN NEW ENGLAND WILL
RESULT IN GENERALLY DRY WEATHER WITH SLIGHTLY BELOW NORMAL TEMPS.
HIGH SHOULD BE HELD IN THE 60S TO AROUND 70...WITH THE COOLEST
READINGS ALONG THE COAST WITH AN ONSHORE FLOW.
THURSDAY NIGHT AND FRIDAY...
SOME UNCERTAINTY WITH A WEAK WAVE OF LOW PRESSURE TRACKING SOUTHEAST
OF THE BENCHMARK. IT LOOKS LIKE AT THIS POINT THAT MOST OF THE
PRECIPITATION WILL STAY OFFSHORE...ALTHOUGH A FEW SPOT SHOWERS MAY
GRAZE THE COAST. WE DID INCLUDE SOME LOW POPS FOR PERHAPS A FEW
SPOT SHOWERS ALONG THE COAST THU NIGHT/FRI WITH THE BEST CHANCE
ACROSS THE CAPE/NANTUCKET. HOWEVER...WERE STILL 60+ HOURS OUT SO
CAN/T COMPLETELY RULE OUT A WETTER SCENARIO IF LATER MODEL RUNS
TREND WEST. LATER SHIFTS WILL HAVE TO MONITOR TRENDS.
SATURDAY AND SUNDAY...
GENERALLY EXPECT A MILD AND MAINLY DRY DAY SATURDAY OUT AHEAD OF A
COLD FRONT. HIGH TEMPS SHOULD RECOVER WELL INTO THE 70S. A COLD
FRONT MAY BRING A ROUND OF SHOWERS SOMETIME SAT NIGHT AND/OR
SUNDAY...BUT TIMING IS LOW THIS FAR OUT.
MONDAY AND TUESDAY...
MAINLY DRY WEATHER WILL PROBABLY FOLLOW WITH NEAR OR JUST BELOW
NORMAL TEMPERATURES FOR THE BEGINNING OF THE NEXT WORK WEEK.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...
A COLD FRONT MAKING ITS WAY THROUGH THE AREA FROM THE W. AN AREA
OF RAINFALL AND MVFR /ISOLATED IFR/ CONDITIONS WILL CONTINUE
PARTICULARLY THROUGH EASTERN MA/RI THROUGH THE NEXT FEW
HOURS...BUT EXPECT GRADUAL IMPROVEMENT AS THE FRONT MOVES THROUGH
THE AREA FROM W TO E. EXPECT THE FRONT THROUGH CENTRAL PORTIONS OF
THE AREA BY ABOUT 08Z...AND CONTINUE MOVING E FROM THERE. IT MAY
TAKE UNTIL AFTER SUNRISE TO LIFT MVFR CONDITIONS AND SHOWERS OVER
THE CAPE AND ISLANDS. ONCE THE WIND SHIFTS TO THE NW...EXPECT
IMPROVEMENT TO VFR CONDITIONS WHICH WILL CONTINUE INTO THE DAY.
WINDS WILL BE GENERALLY DIMINISHING TO SUSTAINED 10-15 KT WITH
GUSTS 20 TO 25 KT LATER THIS MORNING.
KBOS TAF...
MODERATE TO HIGH CONFIDENCE. LINE OF HEAVIER RAINFALL SHOULD BE
GENERALLY CLEAR OF THE TERMINAL BY 0730Z...WITH GRADUAL
IMPROVEMENT FROM MVFR TO VFR ESPECIALLY AFTER WIND SHIFT TO THE WNW
AFTER 09Z.
KBDL TAF...
MODERATE TO HIGH CONFIDENCE. EXPECTING A WIND SHIFT TO THE WNW IN
THE NEXT COUPLE OF HOURS WHICH WILL BEGIN THE GRADUAL IMPROVEMENT
FROM MVFR TO VFR WHICH WILL LAST THROUGH THE DAY.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
WEDNESDAY NIGHT THROUGH SATURDAY...
MODERATE CONFIDENCE. MAINLY VFR CONDITIONS EXPECTED OVER THIS TIME.
CAN/T RULE OUT A PERIOD OF MVFR CEILINGS ALONG THE COAST WITH
ONSHORE FLOW.
SATURDAY NIGHT AND SUNDAY...
LOW TO MODERATE CONFIDENCE. A PERIOD OF MVFR CONDITIONS ARE
POSSIBLE WITH A ROUND OF SHOWERS ASSOCIATED WITH A COLD FRONT. LOW
CONFIDENCE ON TIMING.
&&
.MARINE...
TODAY AND TONIGHT...HIGH CONFIDENCE IN OVERALL TRENDS...LOWER
CONFIDENCE IN EXACT TIMING.
A COLD FRONT WILL BE MOVING OVER THE WATERS DURING THE MORNING
HOURS. THIS WILL ALLOW RAINFALL WITH LOW VSBYS TO GRADUALLY COME
TO AN END FROM W TO E. GALES FORCE WINDS WILL CONTINUE UNTIL THE
FRONT MOVES THROUGH AND WINDS SHIFT TO THE NW INTO THE MID
MORNING. AFTERWARD...WIND GUSTS SHOULD REMAIN GENERALLY 30 KT OR
LESS SO SMALL CRAFT ADVISORIES WILL BE NEEDED INTO THE NIGHT
TONIGHT.
OUTLOOK...THURSDAY THROUGH SUNDAY...
MODERATE TO HIGH CONFIDENCE. NORTHEAST WINDS MAY GUST TO AROUND 25
KNOTS AT TIMES OVER THE OPEN OCEAN WED NIGHT INTO EARLY FRI IN THE
COOL AIR ADVECTION PATTERN. WHILE THE WINDS SHOULD DIMINISH SOME
LATER ON FRI...SCA SEAS MAY LINGER ACROSS THE OUTER-WATERS RIGHT
THROUGH THE WEEKEND. THIS A RESULT OF SWELL FROM A DISTANT LOW
PRESSURE SYSTEM WELL OFFSHORE.
&&
.SURF...
A LINGERING SOUTHERLY SWELL UP TO 7 FT WILL CAUSE A RISK FOR
STRONG RIP CURRENTS AND HIGH SURF PARTICULARLY AT SOUTHERN FACING
BEACHES FOR THE CAPE AND ISLANDS. THE RISK WILL GRADUALLY DIMINISH
DURING THE DAY AS THIS SWELL SUBSIDES. A HIGH SURF ADVISORY HAS
BEEN ISSUED.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...HIGH WIND WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR MAZ018-
019-021>024.
HIGH SURF ADVISORY UNTIL 6 PM EDT THIS EVENING FOR MAZ023-024.
NH...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EDT THURSDAY FOR
NHZ011.
RI...NONE.
MARINE...GALE WARNING UNTIL 11 AM EDT THIS MORNING FOR ANZ231>237-250-
251-254>256.
GALE WARNING UNTIL 10 AM EDT THIS MORNING FOR ANZ230.
&&
$$
SYNOPSIS...BELK/DOODY
NEAR TERM...DOODY
SHORT TERM...DOODY
LONG TERM...FRANK
AVIATION...FRANK/DOODY
MARINE...FRANK/DOODY
TIDES/COASTAL FLOODING...DOODY
AREA FORECAST DISCUSSION
NWS TAUNTON MA
350 AM EDT WED SEP 19 2012
.SYNOPSIS...
A COLD FRONT WILL PUSH THROUGH THE AREA THIS MORNING WITH RAIN
COMING TO AN END AND SKIES GRADUALLY CLEARING. HIGH PRESSURE WILL
THEN BUILD OVER THE AREA THROUGH THE LATTER PART OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
TWO WEAKENING LLJ/S ARE MOVING THROUGH ERN PORTIONS OF THE FA THIS
MORNING. THE FIRST IS ASSOCIATED WITH A WEAK LOW-TOPPED CONVECTIVE
LINE WHICH IS JUST MAKING IT TO CAPE COD AND THE ISLANDS THIS
HOUR. THIS WILL CONTINUE TO PUSH TO THE E AND WILL LIKELY BE
OFFSHORE BY SUNRISE. THE SECOND LLJ IS JUST NOW MOVING INTO THE
SRN COASTAL WATERS AND THE SE COASTAL PLAIN OF RI/MA. WHILE WINDS
ARE GENERALLY WEAKER WITH THIS LLJ...THERE IS ENOUGH MOISTURE WITH
IT THAT IT WILL ALLOW RAINFALL TO LINGER OVER PORTIONS OF SE MA/RI
THROUGH THE MID MORNING TIMEFRAME.
IN ANY CASE A COLD FRONT IS ALREADY MAKING ITS WAY THROUGH CENTRAL
MA ASSOCIATED WITH A TILTING KICKER TROF MOVING INTO SRN NEW
ENGLAND PER LATEST WV IMG. THIS WILL USHER IN SOME COOLER/DRIER
AIR AND PUSH THE RAIN BANDS OFFSHORE BY MID MORNING.
INDEED...DWPTS HAVE ALREADY DROPPED INTO THE LOW 50S IN BERKSHIRE
COUNTY AND WINDS HAVE SHIFTED TO THE NW IN THE CT VALLEY SO THE
DRY AIR IS ALREADY MOVING IN RAPIDLY. THIS WILL ALLOW FOR
GRADUALLY CLEARING SKIES AND IMPROVING CONDITIONS THROUGH THE
MORNING...WITH THE WHOLE AREA EXPECTING TO BE DRY WITH ONLY PARTLY
CLOUDY SKIES BY THE LATE AFTERNOON HOURS. HRRR HAS BEEN HANDLING
POPS RATHER WELL SO TIMING OF PRECIP END IS BASED ON ITS FORECAST.
IN TERMS OF THE WIND THREAT...WILL BE DROPPING WIND ADVISRY/HIGH
WIND WARNINGS FOR ALL AREAS SAVE FOR SE MA...ALTHOUGH THESE
WARNINGS TOO WILL BE ENDING SOON. THE STRONG HIGH PRES MOVING IN
WILL KEEP CONDITIONS COOL AND BREEZY DURING THE DAY TODAY...BUT
MOST WIND GUSTS SHOULD BE 30 MPH OR LESS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
TONIGHT...
HIGH PRES WILL CONTINUE TO BUILD OVER THE REGION FROM THE W WITH
CLEARING SKIES AND DECENT SUBSIDENCE INVERSION. BREEZY CONDITIONS
MAY LINGER INTO THE EVENING HOURS OVER EXTREME ERN PORTIONS OF THE
AREA...BUT EXPECT NEAR CALM CONDITIONS DURING THE LATE NIGHT HOURS
INLAND. THE COMBINATION OF THESE NEAR CALM CONDITIONS...CLEARING
SKIES AND H92 TEMPS DIPPING TO ABOUT +6C IN SRN NH BY LATE
NIGHT...RADIATIONAL COOLING WILL ALLOW TEMPS IN VALLEYS TO DIP
VERY CLOSE TO THE FREEZING MARK. WILL ISSUE A FROST ADVISORY FOR
HILLSBOROUGH COUNTY...WHERE VALLEYS HAVE BEST CHANCE OF DIPPING TO
NEAR FREEZING. THIS LINES UP WITH NEIGHBORS AS WELL. OTHERWISE...
TEMPS RANGING IN THE UPPER 30S TO MID 40S WILL BE LIKELY.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
* DUE TO ONGOING HIGH-IMPACT WEATHER OVERNIGHT LITTLE CHANGE *
* HAS BEEN MADE TO THE LONG TERM. *
HIGHLIGHTS...
* SLIGHTLY BELOW NORMAL TEMPS WED NIGHT AND THU
* MAINLY DRY THROUGH EARLY SAT OTHER THAN A SPOT SHOWER ON COAST
* A COLD FRONT MAY BRING A ROUND OF SHOWERS SOMETIME SAT NIGHT/SUN
* MAINLY DRY WEATHER LIKELY FOLLOWS NEXT MON-TUE
DETAILS...
WEDNESDAY NIGHT...
HIGH PRESSURE BUILDING ACROSS NEW ENGLAND BEHIND THE COLD FRONT WILL
BRING A DRY AND CHILLY NIGHT. LOW TEMPS WILL LIKELY BOTTOM OUT IN
THE MIDDLE TO UPPER 30S ACROSS THE NORMALLY COOLER OUTLYING
LOCATIONS OF SOUTHWEST NH/WESTERN MA...TO MAINLY THE 40S ELSEWHERE.
SOME FROST MAY OCCUR ACROSS OUR NORTHWEST INTERIOR ZONES...BUT ITS
UNCERTAIN WHETHER IT WILL BE WIDESPREAD ENOUGH TO WARRANT A FROST
ADVISORY. SOMETHING LATER SHIFTS WILL HAVE TO CONSIDER.
THURSDAY...
HIGH PRESSURE CENTERED OVER QUEBEC AND NORTHERN NEW ENGLAND WILL
RESULT IN GENERALLY DRY WEATHER WITH SLIGHTLY BELOW NORMAL TEMPS.
HIGH SHOULD BE HELD IN THE 60S TO AROUND 70...WITH THE COOLEST
READINGS ALONG THE COAST WITH AN ONSHORE FLOW.
THURSDAY NIGHT AND FRIDAY...
SOME UNCERTAINTY WITH A WEAK WAVE OF LOW PRESSURE TRACKING SOUTHEAST
OF THE BENCHMARK. IT LOOKS LIKE AT THIS POINT THAT MOST OF THE
PRECIPITATION WILL STAY OFFSHORE...ALTHOUGH A FEW SPOT SHOWERS MAY
GRAZE THE COAST. WE DID INCLUDE SOME LOW POPS FOR PERHAPS A FEW
SPOT SHOWERS ALONG THE COAST THU NIGHT/FRI WITH THE BEST CHANCE
ACROSS THE CAPE/NANTUCKET. HOWEVER...WERE STILL 60+ HOURS OUT SO
CAN/T COMPLETELY RULE OUT A WETTER SCENARIO IF LATER MODEL RUNS
TREND WEST. LATER SHIFTS WILL HAVE TO MONITOR TRENDS.
SATURDAY AND SUNDAY...
GENERALLY EXPECT A MILD AND MAINLY DRY DAY SATURDAY OUT AHEAD OF A
COLD FRONT. HIGH TEMPS SHOULD RECOVER WELL INTO THE 70S. A COLD
FRONT MAY BRING A ROUND OF SHOWERS SOMETIME SAT NIGHT AND/OR
SUNDAY...BUT TIMING IS LOW THIS FAR OUT.
MONDAY AND TUESDAY...
MAINLY DRY WEATHER WILL PROBABLY FOLLOW WITH NEAR OR JUST BELOW
NORMAL TEMPERATURES FOR THE BEGINNING OF THE NEXT WORK WEEK.
&&
.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...
A COLD FRONT MAKING ITS WAY THROUGH THE AREA FROM THE W. AN AREA
OF RAINFALL AND MVFR /ISOLATED IFR/ CONDITIONS WILL CONTINUE
PARTICULARLY THROUGH EASTERN MA/RI THROUGH THE NEXT FEW
HOURS...BUT EXPECT GRADUAL IMPROVEMENT AS THE FRONT MOVES THROUGH
THE AREA FROM W TO E. EXPECT THE FRONT THROUGH CENTRAL PORTIONS OF
THE AREA BY ABOUT 08Z...AND CONTINUE MOVING E FROM THERE. IT MAY
TAKE UNTIL AFTER SUNRISE TO LIFT MVFR CONDITIONS AND SHOWERS OVER
THE CAPE AND ISLANDS. ONCE THE WIND SHIFTS TO THE NW...EXPECT
IMPROVEMENT TO VFR CONDITIONS WHICH WILL CONTINUE INTO THE DAY.
WINDS WILL BE GENERALLY DIMINISHING TO SUSTAINED 10-15 KT WITH
GUSTS 20 TO 25 KT LATER THIS MORNING.
KBOS TAF...
MODERATE TO HIGH CONFIDENCE. LINE OF HEAVIER RAINFALL SHOULD BE
GENERALLY CLEAR OF THE TERMINAL BY 0730Z...WITH GRADUAL
IMPROVEMENT FROM MVFR TO VFR ESPECIALLY AFTER WIND SHIFT TO THE WNW
AFTER 09Z.
KBDL TAF...
MODERATE TO HIGH CONFIDENCE. EXPECTING A WIND SHIFT TO THE WNW IN
THE NEXT COUPLE OF HOURS WHICH WILL BEGIN THE GRADUAL IMPROVEMENT
FROM MVFR TO VFR WHICH WILL LAST THROUGH THE DAY.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
WEDNESDAY NIGHT THROUGH SATURDAY...
MODERATE CONFIDENCE. MAINLY VFR CONDITIONS EXPECTED OVER THIS TIME.
CAN/T RULE OUT A PERIOD OF MVFR CEILINGS ALONG THE COAST WITH
ONSHORE FLOW.
SATURDAY NIGHT AND SUNDAY...
LOW TO MODERATE CONFIDENCE. A PERIOD OF MVFR CONDITIONS ARE
POSSIBLE WITH A ROUND OF SHOWERS ASSOCIATED WITH A COLD FRONT. LOW
CONFIDENCE ON TIMING.
&&
.MARINE...
TODAY AND TONIGHT...HIGH CONFIDENCE IN OVERALL TRENDS...LOWER
CONFIDENCE IN EXACT TIMING.
A COLD FRONT WILL BE MOVING OVER THE WATERS DURING THE MORNING
HOURS. THIS WILL ALLOW RAINFALL WITH LOW VSBYS TO GRADUALLY COME
TO AN END FROM W TO E. GALES FORCE WINDS WILL CONTINUE UNTIL THE
FRONT MOVES THROUGH AND WINDS SHIFT TO THE NW INTO THE MID
MORNING. AFTERWARDS...WIND GUSTS SHOULD REMAIN GENERALLY 30 KT OR
LESS SO SMALL CRAFT ADVISORIES WILL BE NEEDED INTO THE NIGHT
TONIGHT.
OUTLOOK...THURSDAY THROUGH SUNDAY...
MODERATE TO HIGH CONFIDENCE. NORTHEAST WINDS MAY GUST TO AROUND 25
KNOTS AT TIMES OVER THE OPEN OCEAN WED NIGHT INTO EARLY FRI IN THE
COOL AIR ADVECTION PATTERN. WHILE THE WINDS SHOULD DIMINISH SOME
LATER ON FRI...SCA SEAS MAY LINGER ACROSS THE OUTER-WATERS RIGHT
THROUGH THE WEEKEND. THIS A RESULT OF SWELL FROM A DISTANT LOW
PRESSURE SYSTEM WELL OFFSHORE.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...HIGH WIND WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR MAZ018-
019-021>024.
NH...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EDT THURSDAY FOR
NHZ011.
RI...NONE.
MARINE...GALE WARNING UNTIL 11 AM EDT THIS MORNING FOR ANZ231>237-250-
251-254>256.
GALE WARNING UNTIL 10 AM EDT THIS MORNING FOR ANZ230.
&&
$$
SYNOPSIS...BELK/DOODY
NEAR TERM...DOODY
SHORT TERM...DOODY
LONG TERM...FRANK
AVIATION...FRANK/DOODY
MARINE...FRANK/DOODY
AREA FORECAST DISCUSSION
NWS TOPEKA KS
304 AM CDT WED SEP 19 2012
.DISCUSSION...
SURFACE WINDS COMING AROUND TO THE SOUTH ATTM AS NEXT ROUND OF
HIGH PRESSURE GEARS UP TO SLIDE INTO THE CENTRAL PLAINS TODAY.
VIGOROUS SHORTWAVE NOTED ON WV IMAGERY DROPPING INTO NORTH DAKOTA
WHICH WILL AID IN BRINGING A COLD FRONT ACROSS THE STATE.
FOR MUCH OF THE DAY THE AREA WILL BE UNDER THE THERMAL RIDGE OUT
AHEAD OF THE INCOMING FRONT...AND THEREFORE EXPECT TEMPERATURES TO
MIX OUT INTO THE 80S FOR MOST AREAS. FRONTAL TIMING IS A FEW HOURS
DIFFERENT IN MODEL RUNS WITH NAM JUST A FEW HOURS FASTER THAN EC
OR GFS. NOTEWORTHY IN THAT THE SLOWER APPROACH WOULD LEAD TO LOWER
WINDSPEEDS IN THE NORTHERN COUNTIES AND THEREFORE WOULD KEEP THE
AREA OUT OF RED FLAG WEATHER CONDITIONS. RH VALUES EXPECTED TO
DROP TO NEAR 20 IN THE MID TO LATE AFTERNOON. AFTER LOOKING AT
SATELLITE VEGETATION IMAGERY AND AFTER DISCUSSIONS WITH AREA LAND
MANAGERS THINK THE VEGETATION IN OUR FAR NORTHWESTERN COUNTIES ARE
NOT IN A STATE TO CARRY LARGE FIRE GROWTH AND WILL NOT POST A RED
FLAG WARNING AT THIS TIME. FRONT MOVES THROUGH IN THE
EVENING/OVERNIGHT HOURS AND DOES APPEAR TO BRING ONLY CLOUDS
WITHOUT PRECIP. BETTER MIXING AS THE AIRMASS MOVES SOUTH SHOULD
KEEP LOWS IN THE UPPER 40S TO LOWER 50S. WITH THE COOLER AIRMASS
IN PLACE HAVE HIGHS ON TUESDAY IN THE 70S TO NEAR 80 FAR WEST.
ISENTROPIC LIFT OVER THE RETREATING COLD FRONT ALONG WITH SOME
UPPER ENERGY MAY BRING A CHANCE FOR RAIN ACROSS THE SOUTHERN
COUNTIES THURSDAY NIGHT INTO FRIDAY MORNING AND HAVE KEPT POPS
ACROSS THE SOUTHEAST. COOLER AIRMASS AGAIN SLIDES SOUTHWARD INTO
FRIDAY WITH HIGHS GENERALLY IN THE 70S. NEXT SHOT OF COLD AIR
MOVES IN FRIDAY NIGHT INTO SATURDAY MORNING WHICH WILL BRING LOWS
IN THE 40S WITH HIGHS NOT LIKELY TO MAKE IT OUT OF THE 60S ON
SATURDAY. THIS STRONGER HIGH PRESSURE CENTER IS NOSING INTO
EASTERN KANSAS BY SATURDAY MORNING AND MAY HAVE SOME LOCATIONS IN
THE 30S BY SUNRISE WITH ANOTHER DAY OF HIGHS ONLY IN THE 60S.
UPPER NORTHWEST FLOW FINALLY BREAKS BY EARLY NEXT WEEK AND MAY SEE
A RETURN BACK INTO THE 80S FOR MONDAY AND TUESDAY AS UPPER RIDGING
MOVES INTO THE PLAINS STATES. 67
&&
.AVIATION...
THE RAP AND NAM CONTINUE TO SHOW THE LOW LEVEL JET INCREASING TO AT
LEAST 40 KTS AT AROUND 1 KFT...AND AREA PROFILER AND VWP PLOTS SHOW
THE 925 WINDS PICKING UP. WHILE THE SFC PRESSURE GRADIENT MAY
SLIGHTLY STRENGTHEN OVERNIGHT...DO NOT HAVE ENOUGH CONFIDENCE THAT
SFC WINDS WILL INCREASE GIVEN OBJECTIVE GUIDANCE KEEPING SPEEDS IN
THE 5 TO 7 KT RANGE. THEREFORE WILL INCLUDE A MENTION OF LOW LEVEL
WIND SHEAR. OTHERWISE A RELATIVELY DRY AIRMASS SHOULD MAINTAIN VFR
CONDITIONS THROUGH WEDNESDAY EVENING.
WOLTERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1119 PM CDT TUE SEP 18 2012
.DISCUSSION...
SEE PREV DISCUSSION.
&&
.AVIATION...
THE RAP AND NAM CONTINUE TO SHOW THE LOW LEVEL JET INCREASING TO AT
LEAST 40 KTS AT AROUND 1 KFT...AND AREA PROFILER AND VWP PLOTS SHOW
THE 925 WINDS PICKING UP. WHILE THE SFC PRESSURE GRADIENT MAY
SLIGHTLY STRENGTHEN OVERNIGHT...DO NOT HAVE ENOUGH CONFIDENCE THAT
SFC WINDS WILL INCREASE GIVEN OBJECTIVE GUIDANCE KEEPING SPEEDS IN
THE 5 TO 7 KT RANGE. THEREFORE WILL INCLUDE A MENTION OF LOW LEVEL
WIND SHEAR. OTHERWISE A RELATIVELY DRY AIRMASS SHOULD MAINTAIN VFR
CONDITIONS THROUGH WEDNESDAY EVENING.
WOLTERS
&&
.PREV DISCUSSION... /341 PM CDT TUE SEP 18 2012/
WINDS HAVE COME AROUND TO THE SOUTH ACROSS THE WESTERN HALF OF THE
CWA AS THE SURFACE RIDGE MOVES TO THE SOUTHEAST. WINDS WILL BECOME
SOUTH THIS EVENING OVER THE EAST. SKIES WILL REMAIN CLEAR TONIGHT
AND THE LOWER BOUNDARY LAYER WILL BE MIXED AND LOWS WILL WARMER
MAINLY IN THE MID 40S TO LOWER 50S.
WARM ADVECTION AHEAD OF AN APPROACHING FRONT ACROSS NEBRASKA WILL
SEND TEMPERATURES INTO THE MID AND UPPER 80S. WITH THE WARMEST
TEMPERATURES NEAR CENTRAL KANSAS. AFTERNOON RELATIVE HUMIDITY WILL
BE NEAR 20 PERCENT IN NORTH CENTRAL KANSAS BUT WINDS WILL SLACKEN
DURING THE AFTERNOON AS THE THE FRONT APPROACHES. SO NOT GOING TO GO
WITH ANY FIRE WEATHER HEADLINES.
53
NORTHWEST FLOW WILL CONTINUE ACROSS THE COUNTY WARNING AREA THROUGH
THE END OF THE WEEK AND THROUGH THE WEEKEND. THE FRONT LATE
WEDNESDAY/WEDNESDAY NIGHT WILL MOVE THROUGH THE AREA DRY BEFORE
STALLING TO THE SOUTH OF THE AREA ON THURSDAY. THIS WILL RESULT
IN COOLER HIGHS ON THURSDAY IN THE UPPER 70S TO NEAR 80 DEGREES.
AS THE NEXT WAVE DROPS INTO THE PLAINS...VEERING LOW LEVEL FLOW
WILL ALLOW MOISTURE POOLED ALONG AND SOUTH OF THE BOUNDARY TO
ADVANCE BACK TO THE NORTH INTO THE SOUTHERN PORTIONS OF THE CWA
THURSDAY NIGHT AHEAD OF THE NEXT FRONT AND SHORTWAVE TROUGH. WILL
KEEP A CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS GENERALLY THE
SOUTHEAST HALF OF THE CWA THURSDAY NIGHT...ENDING ON FRIDAY IN THE
FAR SOUTHEAST CORNER AS THE FRONT USHERS IN MUCH COOLER AND DRIER
AIR AGAIN. THIS WILL NOT ONLY RESULT IN COOLER HIGHS IN THE 70S
FOR FRIDAY...BUT EVEN COOLER HIGHS IN THE UPPER 60S AND LOWER 70S
ON THROUGH THE WEEKEND AS CANADIAN HIGH PRESSURE DROPS SOUTH
THROUGH THE PLAINS. LOWS WILL GENERALLY BE IN THE 40S...BUT IF
WINDS DECREASE ENOUGH SUNDAY MORNING...SOME LOWS IN THE UPPER 30S
CANNOT BE RULED OUT ACROSS THE NORTHERN COUNTIES. AT THAT POINT...THE
UPPER FLOW WILL BEGIN TO TRANSITION TO A WARMER MORE ZONAL PATTERN
AS THE EASTERN TROUGH SHIFTS EASTWARD AND A LOWER AMPLITUDE
WESTERN TROUGH PERSISTS IN THE GREAT BASIN AREA EARLY NEXT WEEK.
HIGHS MONDAY AND TUESDAY WILL RISE BACK INTO THE UPPER 70S AND
LOWER 80S WITH LOWS GENERALLY IN THE UPPER 40S AND 50S. THE FCST
WILL REMAIN DRY THROUGH TUESDAY. 63
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PORTLAND OR
220 AM PDT WED SEP 19 2012
.SYNOPSIS...INCREASING ONSHORE FLOW IS PRODUCING A COOLING TREND FOR
THE NEXT COUPLE DAYS...PUSHING TEMPERATURES CLOSER TO NORMAL ACROSS
THE INTERIOR. MEANWHILE THE COAST WILL REMAIN COOL AND CLOUDY AS AN
UPPER LEVEL LOW GRADUALLY DEEPENS THE MARINE LAYER. NIGHT AND MORNING
LOW CLOUDS AND FOG WILL PUSH FURTHER INTO THE INTERIOR VALLEYS AS THE
WEEK PROGRESSES.
&&
.SHORT TERM...SATELLITE FOG PRODUCT SHOWS SOLID MARINE LAYER OVER THE
WATERS...PUSHING INTO COASTAL GAPS AND UP THE COLUMBIA JUST PAST
KKLS. MIGHT SEE THE LOW CLOUDS PUSH INTO THE SOUTHERN VALLEY THIS
MORNING...WITH ONLY LIMITED LOW CLOUDS MAKING IT INTO THE NORTHERN
VALLEY. LOW CLOUDS WILL CLEAR TO THE NEAR THE COAST BY EARLY
AFTERNOON. TEMPERATURES NEAR THE INTERSTATE 5 CORRIDORSHOULD BE A
FEW DEGREES COOLER THAN YESTERDAY DUE TO THE ENHANCED MARINE
INFLUENCE. FURTHER INLAND...IN THE COLUMBIA GORGE AND THE
CASCADES...IT IS UNLIKELY THERE WILL BE MUCH COOLDOWN TODAY.
A BROAD UPPER LEVEL LOW PERSISTS WELL OFF THE CALIFORNIA AND SOUTHERN
OREGON COAST. A STRONG PACIFIC JET NOW NEAR 170W AND ASSOCIATED UPPER
TROUGH WILL MOVE THIS SYSTEM EASTWARD TOWARD THE COAST BY FRIDAY.
HOWEVER...MODEL SOLUTIONS CONTINUE TO VARY ON THE DETAILS ON HOW THIS
IS GOING TO HAPPEN. LATEST GFS/ECMWF/GEM/NAM ALL HAVE SOME VARIATION
OF THE UPPER LOW SLOWLY APPROACHING THE WEST COAST FRIDAY.
THE MARINE LAYER WILL SLOWLY DEEPEN OVER THE NEXT FEW DAYS...YIELDING
GREATER INLAND EXTENT OF LOW CLOUDS THU MORNING AND POSSIBLY FRI
MORNING. THIS SUPPORTS THE IDEA OF A GRADUAL COOLDOWN TO NEAR-NORMAL
TEMPS... MID TO UPPER 70S FOR THE INLAND VALLEYS AND AROUND 80 FOR
THE COLUMBIA GORGE...BY FRIDAY. THIS ALSO MEANS THE COAST CAN LOOK
FORWARD TO A COOL AND CLOUDY WEEK...WITH PATCHY DRIZZLE POSSIBLE AT
TIMES.LIKENS
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...SLIGHT MODEL
DISCREPANCIES CONTINUE IN THE EXTENDED PORTION OF THE FORECAST
PERIOD. BEGINNING FRIDAY NIGHT...THE LOW OFFSHORE WILL BEGIN TO MOVE
INLAND. WHERE THE LOW CENTER MOVES ASHORE IS THE BIGGEST DISCREPANCY
BETWEEN VARIOUS MODELS...SO A BLENDED SOLUTION WAS USED TO BRING THE
LOW ASHORE NEAR THE SRN OREGON COAST DURING THE DAY SATURDAY. THIS
PATTERN WOULD BRING CONVECTIVE ACTIVITY AROUND THE LOW TO AT LEAST
THE CASCADES LATE FRIDAY INTO SATURDAY...WITH THE POTENTIAL
CONTINUING THROUGH THE WEEKEND AND POSSIBLY SPREADING IN TO THE
VALLEY AREAS. THE LOW THEN MOVES EAST OF THE FORECAST AREA EARLY NEXT
WEEK. BROWN
&&
.AVIATION...HIGH END IFR TO LOW END MVFR CIGS WILL CONTINUE ALONG
THE COAST WITH LITTLE IN THE WAY TO SUGGEST ANY SIGNIFICANT
CLEARING. THE MARINE LAYER LOOKS TO CONTINUE TO DEEPEN SLIGHTLY
THROUGH THE PERIOD. IFR/MVFR CIGS SHOULD BE ABLE TO PENETRATE INTO
THE SOUTH WILLAMETTE VALLEY AROUND KEUG EARLY THIS MORNING...WITH
LATEST RAP GUIDANCE AND 6Z NAM FINALLY CATCHING UP TO CURRENT
SATELLITE OBSERVATIONS AND SUGGESTING THAT A PERIOD OF LOW MVFR OR
IFR CONDITIONS ARE POSSIBLE IN STRATUS/PATCHY FOG THIS MORNING
AROUND THE NORTH VALLEY TERMINALS...INCLUDING PDX/VUO/TTD. IT WILL
BE A CLOSE CALL AS BOUNDARY LAYER WINDS ARE LIGHT SE AND MOST
GUIDANCE SUGGESTS THE CLOUDS WILL STAY OUT.
KPDX AND APPROACHES...VFR CONDITIONS ARE EXPECTED...BUT A BRIEF
PERIOD OF HIGH END IFR TO LOW END MVFR CIGS IS POSSIBLE BETWEEN
ABOUT 11Z AND 16Z WEDNESDAY. CONFIDENCE OF KPDX CIG IS AROUND
50-60 PERCENT AS MOS GUIDANCE/SREF/AND HRRR SUGGEST THERE IS LITTLE
THREAT...THOUGH CURRENT BUFR SOUNDINGS AND RAP MODEL AND SATELLITE
TRENDS OF LOW CLOUDS INCHING THEIR WAY UP THE COLUMBIA SEEMS TO
SUGGEST OTHERWISE. WILL KEEP THE MENTION IN THE TAF. KMD
&&
.MARINE...WINDS ARE EXPECTED TO REMAIN WELL BELOW SMALL CRAFT
ADVISORY THRESHOLDS THROUGH MOST OF THE WEEK...GENERALLY IN THE 15
KT RANGE OR LESS. SEAS WILL GENERALLY REMAIN IN THE 3 TO 5 FT
RANGE AS WELL. INCREASING WESTERLY SWELL LOOKS TO ARRIVE EARLY
NEXT WEEK...WITH WAVE GUIDANCE INDICATING SEAS INCREASING TO NEAR
10 FT. KMD
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.
&&
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1139 PM CDT TUE SEP 18 2012
.SHORT TERM...TONIGHT INTO TOMORROW MORNING
831 PM CDT TUE SEP 18 2012
THE MAIN SHORT TERM CONCERN IS WITH THE POTENTIAL FOR FROST
OVERNIGHT...PARTICULARLY IN WESTERN WISCONSIN WHERE SKIES WILL BE
CLEAR AND WINDS WILL BE LIGHT FOR A BRIEF PERIOD LATE THIS EVENING
AND EARLY TOMORROW MORNING. SOME OF THE TYPICAL LOW SPOTS THAT RUN
FROM BLACK RIVER FALLS DOWN TO SPARTA AND ACROSS TO VOLK FIELD
FROM JACKSON COUNTY TO JUNEAU COUNTY HAVE ALREADY DROPPED INTO THE
37-40 DEGREE RANGE...BUT OTHER OBSERVATIONS IN SLIGHTLY HIGHER
TERRAIN ARE STILL IN THE 40-50 DEGREE RANGE. CLOUD COVER WILL BE
ON THE INCREASE THROUGH THE NIGHT FROM THE WEST ALONG THE WARM AIR
ADVECTION WING AS WELL AS FROM THE NORTH AS THE MID LEVEL TROUGH
DIVES INTO THE REGION. THE 18.23Z RAP AND 18.18Z NAM/GFS ALL SHOW
THIS BROKEN TO OVERCAST CLOUD COVER MOVING IN ACROSS WESTERN
WISCONSIN AROUND 6Z...WHICH WOULD HELP KEEP TEMPERATURES UP ONCE
IT MOVES IN. WHILE TEMPERATURES WILL DIP IN THESE LOW LYING
LOCATIONS THIS EVENING AND FROST WILL LIKELY FORM IN THEM...IT
WILL LIKELY NOT BE WIDESPREAD ENOUGH ACROSS THIS REGION TO ISSUE
AN ADVISORY FOR OVERNIGHT. ON TOP OF THAT...THE WINDOW FOR
TEMPERATURES TO BE COLD ENOUGH AND WINDS TO REMAIN LIGHT TO
PRODUCE FROST IS SHORT ENOUGH THAT THE IMPACTS FROM A TRUE FROST
MAY NOT OCCUR. ALL OF THIS LEADS TO CONFIDENCE NOT BEING HIGH
ENOUGH TO PULL THE TRIGGER ON AN ADVISORY.
.LONG TERM...SATURDAY THROUGH TUESDAY
230 PM CDT TUE SEP 18 2012
MODELS REMAIN VERY PERSISTENT ON HAVING THE DEEP UPPER LEVEL TROUGH
IMPACT THE AREA...WITH THIS DIRTY CYCLONIC FLOW SPITTING A SHORTWAVE
OR TWO ACROSS THE REGION. SOME DIFFERENCES IN TIMING AND POSITIONING
OF THE BITS OF ENERGY...BUT ALL POINT TO A CONTINUATION OF THE BELOW
NORMAL TEMPERATURES.
THE MODELS DO SUGGEST THAT THE TROUGH WILL FINALLY PUSH EAST FOR THE
BEGINNING OF NEXT WEEK. THE REGION WILL STILL BE UNDER NORTHWEST
FLOW...BUT TEMPERATURES SHOULD REBOUND CLOSER TO THE SEASONABLE
NORMALS.
&&
.AVIATION...THROUGH 06Z THURSDAY
1139 PM CDT TUE SEP 18 2012
THE MAIN FORECAST CONCERNS ARE WITH THE PRECIPITATION CHANCES
WEDNESDAY AFTERNOON AS A COLD FRONT MOVES THROUGH THE REGION.
UPPER LEVEL CLOUD COVER IS CURRENTLY ON THE INCREASE AS A WARM
FRONT LIFTS NORTHEAST ACROSS MINNESOTA INTO WESTERN WISCONSIN.
SURFACE WINDS HAVE STARTED TO INCREASE AS THE SURFACE LOW DROPS
DOWN FROM SOUTH CENTRAL CANADA. LOW LEVEL WINDS HAVE ALSO BEGUN TO
PICK UP AND WILL LIKELY LEAD TO SOME LOW LEVEL WIND SHEAR WITH
WIND SPEEDS INCREASING TO AROUND 50KT BY 2KFT. THE STRONGEST CORE
OF LOW LEVEL WINDS APPEAR TO MOVE ACROSS RST AND LSE BETWEEN
08-15Z WEDNESDAY MORNING BEFORE SHIFTING TO THE EAST.
WINDS WILL BE STRONG OUT OF THE SOUTHWEST THROUGH MUCH OF THE DAY
WITH GUSTS TOPPING OUT AROUND 30KTS AT TIMES. SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO DEVELOP BY MID AFTERNOON AHEAD OF A
COLD FRONT THAT WILL BE ANGLED FROM NORTHEAST TO SOUTHWEST FROM
NORTH CENTRAL WISCONSIN TO SOUTH CENTRAL MINNESOTA. THESE
SHOWERS/STORMS WILL BE VERY BRIEF AHEAD OF THE FRONT AS IT MOVES
THROUGH RST/LSE BETWEEN 20-23Z. CONFIDENCE IS NOT HIGH ENOUGH YET
TO PUT A MENTION OF THUNDER IN THE TAFS...BUT IT AT LEAST LOOKS
POSSIBLE AS SOME INSTABILITY BUILDS AHEAD OF THE FRONT IN THE
AFTERNOON. CONDITIONS SHOULD BE VFR THROUGH THE NEXT 24
HOURS...THOUGH A VERY BRIEF DROP TO MVFR OR IFR CAN NOT BE RULED
OUT IF A FEW THUNDERSTORMS DEVELOP.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
230 PM CDT TUE SEP 18 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM....RIECK
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
948 AM MDT WED SEP 19 2012
.UPDATE...
&&
.SHORT TERM...SURFACE ANALYSIS SHOWING FRONT MOVING INTO NORTHERN
WELD...LOGAN...PHILLIPS AND SEDGWICK COUNTIES AT THIS TIME. MAS
PRESSURE CHANGE INDICATING RISES OVER MUCH OF THE PLAINS. HRRR
AND RUC STILL INDICATING FRONT TO MOVE ACROSS PLAINS BY 16Z. COULD
STILL SEE SOME GUSTS AROUND 30 MPH FOR A SHORT TIME DURING THE
MORNING. BUT BY 18Z...MODELS CONTINUE TO INDICATE DECREASING WINDS
AS GRADIENT RELAXES. MAY BRIEFLY SEE CONDITIONS MEET RED FLAG
CRITERIA ACROSS FAR EASTERN PLAINS THIS MORNING AS HUMIDITY WILL
BE LOW...BUT LOOKS TO BE SHORT LIVED AND WILL HOLD OFF ON ANY RED
FLAG WARNING. OTHERWISE...CURRENT FORECASTS LOOK ON TRACK...SO NO
MAJOR CHANGES EXPECTED.
.AVIATION...CURRENT TAF TRENDS LOOKING REASONABLE. FRONT STILL
EXPECTED TO PUSH ACROSS AREA AIRPORTS AROUND 16Z OR SHORTLY
THEREAFTER WITH SOME GUSTS AROUND 25 KTS POSSIBLE UNTIL AROUND
19Z. AIRMASS DRY SO NO THREAT OF ANY LOW CLOUDS.
&&
.PREV DISCUSSION... /ISSUED 323 AM MDT WED SEP 19 2012/
SHORT TERM...AN UPPER RIDGE OVER THE WESTERN STATES AND AN UPPER
TROUGH OVER THE GREAT LAKES REGION WILL KEEP DRY NORTHWESTERLY
FLOW OVER COLORADO TODAY AND TONIGHT. A SLIGHT DISTURBANCE IN THE
FLOW WILL PUSH A SURFACE TROUGH OVER THE CO/KS BORDER EAST INTO
THE GREAT PLAINS. THIS WILL ALLOW A COOL FRONT...CURRENTLY UP BY
THE WY/MT BORDER...TO PUSH DOWN SOUTH ACROSS THE COLORADO PLAINS
BEGINNING LATE THIS MORNING. NORTHERLY WINDS BEHIND THIS FRONT
WILL BE AROUND 10 TO 20 MPH WITH GUSTS UP TO 30 MPH AT TIMES.
HUMIDITY LEVELS WILL BE LOW AGAIN...BUT ANTICIPATING TO STAY
WETTER THAN CRITERIA FOR ANY FIRE WEATHER HIGHLIGHTS. THE AREA OF
CONCERN WOULD BE GENERALLY ALONG AND EAST OF A LINE FROM STERLING
TO LIMON. BY LATE AFTERNOON THE WINDS WILL BE DIMINISHING AND
BECOMING LIGHT EASTERLY UPSLOPE DIRECTION AND HUMIDITIES WILL
BEGIN TO INCREASE. MAX TEMPERATURES WILL BE SIMILAR TO YESTERDAY
EXCEPT A FEW DEGREES COOLER OVER THE NORTHERN PARTS OF THE
FORECAST AREA AND A FEW DEGREES WARMER OVER THE SOUTHERN
HALF...DUE TO THE FRONTAL PASSAGE. WILL SEE SOME SCATTERED HIGH
CLOUDS TODAY AND INTO TONIGHT...MAINLY OVER THE NORTHEAST CORNER
AS WELL AS SOME HINTS OF WAVE CLOUDS FORMING OVER THE FRONT RANGE
MOUNTAINS AND FOOTHILLS.
LONG TERM...DRY NORTHWEST FLOW WILL REMAIN OVER THE FORECAST AREA
THROUGH THE WEEKEND. THERE ARE JUST A COUPLE SURGES OF COOL AIR TO
DEAL WITH...ONE WEAK PUSH FRIDAY MORNING AND A SECOND SOMEWHAT
STRONGER ONE FRIDAY NIGHT. THIS WILL BRING SLIGHT COOLING ON
FRIDAY AND A FEW MORE DEGREES SATURDAY. THE LATEST MODEL RUNS HAVE
BEEN TRENDING TOWARD A STRONGER DISTURBANCE DROPPING INTO THE
GREAT LAKES REGION AND THUS A STRONGER ASSOCIATED COLD FRONT
MOVING ACROSS THE PLAINS SATURDAY...SO HAVE SHAVED A COUPLE MORE
DEGREES OFF SATURDAYS HIGHS. SUNDAYS WARMUP COULD EVEN BE DELAYED
A BIT.
THERE ARE SIGNS OF A LITTLE BETTER CHANCE OF SHOWERS AND
THUNDERSTORMS DEVELOPING IN THE MOUNTAINS BY EARLY NEXT WEEK.
MOST MEDIUM RANGE MODELS AND ENSEMBLES POINT TO A WEAK SHORT WAVE
PUSHING EASTWARD INTO THE CENTRAL ROCKIES BY TUESDAY OR TUESDAY
NIGHT. DEPENDING ON EVENTUAL SPEED OF THIS DISTURBANCE...A FEW
SHOWERS/STORMS MAY SPILL OUT ONTO THE PLAINS BY TUESDAY AFTERNOON
SO OPTED TO INTRODUCE A SLIGHT CHANCE OF STORMS ON THE ADJACENT
PLAINS/PALMER DIVIDE AREA.
AVIATION...VFR THROUGH THE PERIOD. DRAINAGE WINDS EARLY THIS
MORNING WILL BECOME NORTHERLY MID TO LATE MORNING WITH GUSTS UP TO
25 KTS WITH A FRONTAL PASSAGE. THESE WILL VEER THROUGH EAST-
SOUTHEAST AND SOUTH DURING THE AFTERNOON TO BECOME DRAINAGE AGAIN
TONIGHT.
HYDROLOGY...NO ISSUES THROUGH THE WEEKEND.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....BARJENBRUCH
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS TAUNTON MA
730 AM EDT WED SEP 19 2012
.SYNOPSIS...
A COLD FRONT WILL PUSH THROUGH THE AREA THIS MORNING WITH RAIN
COMING TO AN END AND SKIES GRADUALLY CLEARING. HIGH PRESSURE WILL
THEN BUILD OVER THE AREA THROUGH THE LATTER PART OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
730 AM UPDATE...
ONLY MINOR TWEAKS TO THE ONGOING FORECAST...MAINLY TO ADJUST
TIMING OF SHOWERS.
PREVIOUS DISCUSSION...
WILL BE DROPPING THE LAST REMAINING HIGH WIND ADVISORY FOR
SOUTHEAST MA. WIND GUSTS HAVE DRAMATICALLY DROPPED OFF AND THE
COLD FRONT CURRENTLY FROM RI TO CAPE AN WILL USHER IN NW FLOW WITH
WIND GUSTS GENERALLY BELOW 30 MPH.
PREVIOUS DISCUSSION...
TWO WEAKENING LLJ/S ARE MOVING THROUGH ERN PORTIONS OF THE FA
THIS MORNING. THE FIRST IS ASSOCIATED WITH A WEAK LOW- TOPPED
CONVECTIVE LINE WHICH IS JUST MAKING IT TO CAPE COD AND THE
ISLANDS THIS HOUR. THIS WILL CONTINUE TO PUSH TO THE E AND WILL
LIKELY BE OFFSHORE BY SUNRISE. THE SECOND LLJ IS JUST NOW MOVING
INTO THE SRN COASTAL WATERS AND THE SE COASTAL PLAIN OF RI/MA.
WHILE WINDS ARE GENERALLY WEAKER WITH THIS LLJ...THERE IS ENOUGH
MOISTURE WITH IT THAT IT WILL ALLOW RAINFALL TO LINGER OVER
PORTIONS OF SE MA/RI THROUGH THE MID MORNING TIMEFRAME.
IN ANY CASE A COLD FRONT IS ALREADY MAKING ITS WAY THROUGH CENTRAL
MA ASSOCIATED WITH A TILTING KICKER TROF MOVING INTO SRN NEW
ENGLAND PER LATEST WV IMG. THIS WILL USHER IN SOME COOLER/DRIER
AIR AND PUSH THE RAIN BANDS OFFSHORE BY MID MORNING.
INDEED...DWPTS HAVE ALREADY DROPPED INTO THE LOW 50S IN BERKSHIRE
COUNTY AND WINDS HAVE SHIFTED TO THE NW IN THE CT VALLEY SO THE
DRY AIR IS ALREADY MOVING IN RAPIDLY. THIS WILL ALLOW FOR
GRADUALLY CLEARING SKIES AND IMPROVING CONDITIONS THROUGH THE
MORNING...WITH THE WHOLE AREA EXPECTING TO BE DRY WITH ONLY PARTLY
CLOUDY SKIES BY THE LATE AFTERNOON HOURS. HRRR HAS BEEN HANDLING
POPS RATHER WELL SO TIMING OF PRECIP END IS BASED ON ITS FORECAST.
IN TERMS OF THE WIND THREAT...WILL BE DROPPING WIND ADVISORY/HIGH
WIND WARNINGS FOR ALL AREAS SAVE FOR SE MA...ALTHOUGH THESE
WARNINGS TOO WILL BE ENDING SOON. THE STRONG HIGH PRES MOVING IN
WILL KEEP CONDITIONS COOL AND BREEZY DURING THE DAY TODAY...BUT
MOST WIND GUSTS SHOULD BE 30 MPH OR LESS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
TONIGHT...
HIGH PRES WILL CONTINUE TO BUILD OVER THE REGION FROM THE W WITH
CLEARING SKIES AND DECENT SUBSIDENCE INVERSION. BREEZY CONDITIONS
MAY LINGER INTO THE EVENING HOURS OVER EXTREME ERN PORTIONS OF THE
AREA...BUT EXPECT NEAR CALM CONDITIONS DURING THE LATE NIGHT HOURS
INLAND. THE COMBINATION OF THESE NEAR CALM CONDITIONS...CLEARING
SKIES AND H92 TEMPS DIPPING TO ABOUT +6C IN SRN NH BY LATE
NIGHT...RADIATIONAL COOLING WILL ALLOW TEMPS IN VALLEYS TO DIP
VERY CLOSE TO THE FREEZING MARK. WILL ISSUE A FROST ADVISORY FOR
HILLSBOROUGH COUNTY...WHERE VALLEYS HAVE BEST CHANCE OF DIPPING TO
NEAR FREEZING. THIS LINES UP WITH NEIGHBORS AS WELL. OTHERWISE...
TEMPS RANGING IN THE UPPER 30S TO MID 40S WILL BE LIKELY.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
* DUE TO ONGOING HIGH-IMPACT WEATHER OVERNIGHT LITTLE CHANGE *
* HAS BEEN MADE TO THE LONG TERM. *
HIGHLIGHTS...
* SLIGHTLY BELOW NORMAL TEMPS WED NIGHT AND THU
* MAINLY DRY THROUGH EARLY SAT OTHER THAN A SPOT SHOWER ON COAST
* A COLD FRONT MAY BRING A ROUND OF SHOWERS SOMETIME SAT NIGHT/SUN
* MAINLY DRY WEATHER LIKELY FOLLOWS NEXT MON-TUE
DETAILS...
WEDNESDAY NIGHT...
HIGH PRESSURE BUILDING ACROSS NEW ENGLAND BEHIND THE COLD FRONT WILL
BRING A DRY AND CHILLY NIGHT. LOW TEMPS WILL LIKELY BOTTOM OUT IN
THE MIDDLE TO UPPER 30S ACROSS THE NORMALLY COOLER OUTLYING
LOCATIONS OF SOUTHWEST NH/WESTERN MA...TO MAINLY THE 40S ELSEWHERE.
SOME FROST MAY OCCUR ACROSS OUR NORTHWEST INTERIOR ZONES...BUT ITS
UNCERTAIN WHETHER IT WILL BE WIDESPREAD ENOUGH TO WARRANT A FROST
ADVISORY. SOMETHING LATER SHIFTS WILL HAVE TO CONSIDER.
THURSDAY...
HIGH PRESSURE CENTERED OVER QUEBEC AND NORTHERN NEW ENGLAND WILL
RESULT IN GENERALLY DRY WEATHER WITH SLIGHTLY BELOW NORMAL TEMPS.
HIGH SHOULD BE HELD IN THE 60S TO AROUND 70...WITH THE COOLEST
READINGS ALONG THE COAST WITH AN ONSHORE FLOW.
THURSDAY NIGHT AND FRIDAY...
SOME UNCERTAINTY WITH A WEAK WAVE OF LOW PRESSURE TRACKING SOUTHEAST
OF THE BENCHMARK. IT LOOKS LIKE AT THIS POINT THAT MOST OF THE
PRECIPITATION WILL STAY OFFSHORE...ALTHOUGH A FEW SPOT SHOWERS MAY
GRAZE THE COAST. WE DID INCLUDE SOME LOW POPS FOR PERHAPS A FEW
SPOT SHOWERS ALONG THE COAST THU NIGHT/FRI WITH THE BEST CHANCE
ACROSS THE CAPE/NANTUCKET. HOWEVER...WERE STILL 60+ HOURS OUT SO
CAN/T COMPLETELY RULE OUT A WETTER SCENARIO IF LATER MODEL RUNS
TREND WEST. LATER SHIFTS WILL HAVE TO MONITOR TRENDS.
SATURDAY AND SUNDAY...
GENERALLY EXPECT A MILD AND MAINLY DRY DAY SATURDAY OUT AHEAD OF A
COLD FRONT. HIGH TEMPS SHOULD RECOVER WELL INTO THE 70S. A COLD
FRONT MAY BRING A ROUND OF SHOWERS SOMETIME SAT NIGHT AND/OR
SUNDAY...BUT TIMING IS LOW THIS FAR OUT.
MONDAY AND TUESDAY...
MAINLY DRY WEATHER WILL PROBABLY FOLLOW WITH NEAR OR JUST BELOW
NORMAL TEMPERATURES FOR THE BEGINNING OF THE NEXT WORK WEEK.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...
A COLD FRONT WAS LOCATED ALONG THE EAST COAST...AND WILL MOVE
ACROSS THE CAPE AND ISLANDS LATER THIS MORNING. HEAVIEST RAINFALL
HAS MOVED OFF THE COAST...AND SHOULD STAY OFFSHORE THIS MORNING.
ONCE THE WIND SHIFTS TO THE NW...EXPECT IMPROVEMENT TO VFR
CONDITIONS WHICH WILL CONTINUE INTO THE DAY. WINDS WILL BE
GENERALLY DIMINISHING TO SUSTAINED 10-15 KT WITH GUSTS 20 TO 25 KT
LATER THIS MORNING.
KBOS TAF...
HIGH CONFIDENCE IN TAF.
KBDL TAF...
HIGH CONFIDENCE IN TAF.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
WEDNESDAY NIGHT THROUGH SATURDAY...
MODERATE CONFIDENCE. MAINLY VFR CONDITIONS EXPECTED OVER THIS TIME.
CAN/T RULE OUT A PERIOD OF MVFR CEILINGS ALONG THE COAST WITH
ONSHORE FLOW.
SATURDAY NIGHT AND SUNDAY...
LOW TO MODERATE CONFIDENCE. A PERIOD OF MVFR CONDITIONS ARE
POSSIBLE WITH A ROUND OF SHOWERS ASSOCIATED WITH A COLD FRONT. LOW
CONFIDENCE ON TIMING.
&&
.MARINE...
TODAY AND TONIGHT...HIGH CONFIDENCE IN OVERALL TRENDS...LOWER
CONFIDENCE IN EXACT TIMING.
6 AM UPDATE...
HAVE DROPPED GALES TO SMALL CRAFT ADVISORIES FOR ALL WATERS.
BOSTON HARBOR AND IPSWICH BAY SHOULD SEE SCA CONDITIONS ENDING BY
THIS AFTERNOON...HOWEVER THE THREAT FOR 25 KT WINDS TONIGHT INTO
TOMORROW AS WELL AS A LINGERING SWELL WILL KEEP SCA/S GOING FOR
REMAINING WATERS.
PREVIOUS DISCUSSION...
A COLD FRONT WILL BE MOVING OVER THE WATERS DURING THE MORNING
HOURS. THIS WILL ALLOW RAINFALL WITH LOW VSBYS TO GRADUALLY COME
TO AN END FROM W TO E. GALES FORCE WINDS WILL CONTINUE UNTIL THE
FRONT MOVES THROUGH AND WINDS SHIFT TO THE NW INTO THE MID
MORNING. AFTERWARD...WIND GUSTS SHOULD REMAIN GENERALLY 30 KT OR
LESS SO SMALL CRAFT ADVISORIES WILL BE NEEDED INTO THE NIGHT
TONIGHT.
OUTLOOK...THURSDAY THROUGH SUNDAY...
MODERATE TO HIGH CONFIDENCE. NORTHEAST WINDS MAY GUST TO AROUND 25
KNOTS AT TIMES OVER THE OPEN OCEAN WED NIGHT INTO EARLY FRI IN THE
COOL AIR ADVECTION PATTERN. WHILE THE WINDS SHOULD DIMINISH SOME
LATER ON FRI...SCA SEAS MAY LINGER ACROSS THE OUTER-WATERS RIGHT
THROUGH THE WEEKEND. THIS A RESULT OF SWELL FROM A DISTANT LOW
PRESSURE SYSTEM WELL OFFSHORE.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...HIGH SURF ADVISORY UNTIL 6 PM EDT THIS EVENING FOR MAZ023-024.
NH...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EDT THURSDAY FOR
NHZ011.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR ANZ231-232-
250-254>256.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ233-
234-236.
SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR ANZ230-
251.
SMALL CRAFT ADVISORY UNTIL 2 AM EDT THURSDAY FOR ANZ235-237.
&&
$$
SYNOPSIS...BELK/DOODY
NEAR TERM...BELK/DOODY
SHORT TERM...DOODY
LONG TERM...FRANK
AVIATION...FRANK/DOODY
MARINE...FRANK/DOODY
AREA FORECAST DISCUSSION
NWS TAUNTON MA
602 AM EDT WED SEP 19 2012
.SYNOPSIS...
A COLD FRONT WILL PUSH THROUGH THE AREA THIS MORNING WITH RAIN
COMING TO AN END AND SKIES GRADUALLY CLEARING. HIGH PRESSURE WILL
THEN BUILD OVER THE AREA THROUGH THE LATTER PART OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
6 AM UPDATE...
WILL BE DROPPING THE LAST REMAINING HIGH WIND ADVISORY FOR
SOUTHEAST MA. WIND GUSTS HAVE DRAMATICALLY DROPPED OFF AND THE
COLD FRONT CURRENTLY FROM RI TO CAPE AN WILL USHER IN NW FLOW WITH
WIND GUSTS GENERALLY BELOW 30 MPH.
PREVIOUS DISCUSSION...
TWO WEAKENING LLJ/S ARE MOVING THROUGH ERN PORTIONS OF THE FA
THIS MORNING. THE FIRST IS ASSOCIATED WITH A WEAK LOW- TOPPED
CONVECTIVE LINE WHICH IS JUST MAKING IT TO CAPE COD AND THE
ISLANDS THIS HOUR. THIS WILL CONTINUE TO PUSH TO THE E AND WILL
LIKELY BE OFFSHORE BY SUNRISE. THE SECOND LLJ IS JUST NOW MOVING
INTO THE SRN COASTAL WATERS AND THE SE COASTAL PLAIN OF RI/MA.
WHILE WINDS ARE GENERALLY WEAKER WITH THIS LLJ...THERE IS ENOUGH
MOISTURE WITH IT THAT IT WILL ALLOW RAINFALL TO LINGER OVER
PORTIONS OF SE MA/RI THROUGH THE MID MORNING TIMEFRAME.
IN ANY CASE A COLD FRONT IS ALREADY MAKING ITS WAY THROUGH CENTRAL
MA ASSOCIATED WITH A TILTING KICKER TROF MOVING INTO SRN NEW
ENGLAND PER LATEST WV IMG. THIS WILL USHER IN SOME COOLER/DRIER
AIR AND PUSH THE RAIN BANDS OFFSHORE BY MID MORNING.
INDEED...DWPTS HAVE ALREADY DROPPED INTO THE LOW 50S IN BERKSHIRE
COUNTY AND WINDS HAVE SHIFTED TO THE NW IN THE CT VALLEY SO THE
DRY AIR IS ALREADY MOVING IN RAPIDLY. THIS WILL ALLOW FOR
GRADUALLY CLEARING SKIES AND IMPROVING CONDITIONS THROUGH THE
MORNING...WITH THE WHOLE AREA EXPECTING TO BE DRY WITH ONLY PARTLY
CLOUDY SKIES BY THE LATE AFTERNOON HOURS. HRRR HAS BEEN HANDLING
POPS RATHER WELL SO TIMING OF PRECIP END IS BASED ON ITS FORECAST.
IN TERMS OF THE WIND THREAT...WILL BE DROPPING WIND ADVISORY/HIGH
WIND WARNINGS FOR ALL AREAS SAVE FOR SE MA...ALTHOUGH THESE
WARNINGS TOO WILL BE ENDING SOON. THE STRONG HIGH PRES MOVING IN
WILL KEEP CONDITIONS COOL AND BREEZY DURING THE DAY TODAY...BUT
MOST WIND GUSTS SHOULD BE 30 MPH OR LESS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
TONIGHT...
HIGH PRES WILL CONTINUE TO BUILD OVER THE REGION FROM THE W WITH
CLEARING SKIES AND DECENT SUBSIDENCE INVERSION. BREEZY CONDITIONS
MAY LINGER INTO THE EVENING HOURS OVER EXTREME ERN PORTIONS OF THE
AREA...BUT EXPECT NEAR CALM CONDITIONS DURING THE LATE NIGHT HOURS
INLAND. THE COMBINATION OF THESE NEAR CALM CONDITIONS...CLEARING
SKIES AND H92 TEMPS DIPPING TO ABOUT +6C IN SRN NH BY LATE
NIGHT...RADIATIONAL COOLING WILL ALLOW TEMPS IN VALLEYS TO DIP
VERY CLOSE TO THE FREEZING MARK. WILL ISSUE A FROST ADVISORY FOR
HILLSBOROUGH COUNTY...WHERE VALLEYS HAVE BEST CHANCE OF DIPPING TO
NEAR FREEZING. THIS LINES UP WITH NEIGHBORS AS WELL. OTHERWISE...
TEMPS RANGING IN THE UPPER 30S TO MID 40S WILL BE LIKELY.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
* DUE TO ONGOING HIGH-IMPACT WEATHER OVERNIGHT LITTLE CHANGE *
* HAS BEEN MADE TO THE LONG TERM. *
HIGHLIGHTS...
* SLIGHTLY BELOW NORMAL TEMPS WED NIGHT AND THU
* MAINLY DRY THROUGH EARLY SAT OTHER THAN A SPOT SHOWER ON COAST
* A COLD FRONT MAY BRING A ROUND OF SHOWERS SOMETIME SAT NIGHT/SUN
* MAINLY DRY WEATHER LIKELY FOLLOWS NEXT MON-TUE
DETAILS...
WEDNESDAY NIGHT...
HIGH PRESSURE BUILDING ACROSS NEW ENGLAND BEHIND THE COLD FRONT WILL
BRING A DRY AND CHILLY NIGHT. LOW TEMPS WILL LIKELY BOTTOM OUT IN
THE MIDDLE TO UPPER 30S ACROSS THE NORMALLY COOLER OUTLYING
LOCATIONS OF SOUTHWEST NH/WESTERN MA...TO MAINLY THE 40S ELSEWHERE.
SOME FROST MAY OCCUR ACROSS OUR NORTHWEST INTERIOR ZONES...BUT ITS
UNCERTAIN WHETHER IT WILL BE WIDESPREAD ENOUGH TO WARRANT A FROST
ADVISORY. SOMETHING LATER SHIFTS WILL HAVE TO CONSIDER.
THURSDAY...
HIGH PRESSURE CENTERED OVER QUEBEC AND NORTHERN NEW ENGLAND WILL
RESULT IN GENERALLY DRY WEATHER WITH SLIGHTLY BELOW NORMAL TEMPS.
HIGH SHOULD BE HELD IN THE 60S TO AROUND 70...WITH THE COOLEST
READINGS ALONG THE COAST WITH AN ONSHORE FLOW.
THURSDAY NIGHT AND FRIDAY...
SOME UNCERTAINTY WITH A WEAK WAVE OF LOW PRESSURE TRACKING SOUTHEAST
OF THE BENCHMARK. IT LOOKS LIKE AT THIS POINT THAT MOST OF THE
PRECIPITATION WILL STAY OFFSHORE...ALTHOUGH A FEW SPOT SHOWERS MAY
GRAZE THE COAST. WE DID INCLUDE SOME LOW POPS FOR PERHAPS A FEW
SPOT SHOWERS ALONG THE COAST THU NIGHT/FRI WITH THE BEST CHANCE
ACROSS THE CAPE/NANTUCKET. HOWEVER...WERE STILL 60+ HOURS OUT SO
CAN/T COMPLETELY RULE OUT A WETTER SCENARIO IF LATER MODEL RUNS
TREND WEST. LATER SHIFTS WILL HAVE TO MONITOR TRENDS.
SATURDAY AND SUNDAY...
GENERALLY EXPECT A MILD AND MAINLY DRY DAY SATURDAY OUT AHEAD OF A
COLD FRONT. HIGH TEMPS SHOULD RECOVER WELL INTO THE 70S. A COLD
FRONT MAY BRING A ROUND OF SHOWERS SOMETIME SAT NIGHT AND/OR
SUNDAY...BUT TIMING IS LOW THIS FAR OUT.
MONDAY AND TUESDAY...
MAINLY DRY WEATHER WILL PROBABLY FOLLOW WITH NEAR OR JUST BELOW
NORMAL TEMPERATURES FOR THE BEGINNING OF THE NEXT WORK WEEK.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
OVERVIEW...
A COLD FRONT MAKING ITS WAY THROUGH THE AREA FROM THE W. AN AREA
OF RAINFALL AND MVFR /ISOLATED IFR/ CONDITIONS WILL CONTINUE
PARTICULARLY THROUGH EASTERN MA/RI THROUGH THE NEXT FEW
HOURS...BUT EXPECT GRADUAL IMPROVEMENT AS THE FRONT MOVES THROUGH
THE AREA FROM W TO E. EXPECT THE FRONT THROUGH CENTRAL PORTIONS OF
THE AREA BY ABOUT 08Z...AND CONTINUE MOVING E FROM THERE. IT MAY
TAKE UNTIL AFTER SUNRISE TO LIFT MVFR CONDITIONS AND SHOWERS OVER
THE CAPE AND ISLANDS. ONCE THE WIND SHIFTS TO THE NW...EXPECT
IMPROVEMENT TO VFR CONDITIONS WHICH WILL CONTINUE INTO THE DAY.
WINDS WILL BE GENERALLY DIMINISHING TO SUSTAINED 10-15 KT WITH
GUSTS 20 TO 25 KT LATER THIS MORNING.
KBOS TAF...
MODERATE TO HIGH CONFIDENCE. LINE OF HEAVIER RAINFALL SHOULD BE
GENERALLY CLEAR OF THE TERMINAL BY 0730Z...WITH GRADUAL
IMPROVEMENT FROM MVFR TO VFR ESPECIALLY AFTER WIND SHIFT TO THE WNW
AFTER 09Z.
KBDL TAF...
MODERATE TO HIGH CONFIDENCE. EXPECTING A WIND SHIFT TO THE WNW IN
THE NEXT COUPLE OF HOURS WHICH WILL BEGIN THE GRADUAL IMPROVEMENT
FROM MVFR TO VFR WHICH WILL LAST THROUGH THE DAY.
OUTLOOK...WEDNESDAY NIGHT THROUGH SATURDAY...
WEDNESDAY NIGHT THROUGH SATURDAY...
MODERATE CONFIDENCE. MAINLY VFR CONDITIONS EXPECTED OVER THIS TIME.
CAN/T RULE OUT A PERIOD OF MVFR CEILINGS ALONG THE COAST WITH
ONSHORE FLOW.
SATURDAY NIGHT AND SUNDAY...
LOW TO MODERATE CONFIDENCE. A PERIOD OF MVFR CONDITIONS ARE
POSSIBLE WITH A ROUND OF SHOWERS ASSOCIATED WITH A COLD FRONT. LOW
CONFIDENCE ON TIMING.
&&
.MARINE...
TODAY AND TONIGHT...HIGH CONFIDENCE IN OVERALL TRENDS...LOWER
CONFIDENCE IN EXACT TIMING.
6 AM UPDATE...
HAVE DROPPED GALES TO SMALL CRAFT ADVISORIES FOR ALL WATERS.
BOSTON HARBOR AND IPSWICH BAY SHOULD SEE SCA CONDITIONS ENDING BY
THIS AFTERNOON...HOWEVER THE THREAT FOR 25 KT WINDS TONIGHT INTO
TOMORROW AS WELL AS A LINGERING SWELL WILL KEEP SCA/S GOING FOR
REMAINING WATERS.
PREVIOUS DISCUSSION...
A COLD FRONT WILL BE MOVING OVER THE WATERS DURING THE MORNING
HOURS. THIS WILL ALLOW RAINFALL WITH LOW VSBYS TO GRADUALLY COME
TO AN END FROM W TO E. GALES FORCE WINDS WILL CONTINUE UNTIL THE
FRONT MOVES THROUGH AND WINDS SHIFT TO THE NW INTO THE MID
MORNING. AFTERWARD...WIND GUSTS SHOULD REMAIN GENERALLY 30 KT OR
LESS SO SMALL CRAFT ADVISORIES WILL BE NEEDED INTO THE NIGHT
TONIGHT.
OUTLOOK...THURSDAY THROUGH SUNDAY...
MODERATE TO HIGH CONFIDENCE. NORTHEAST WINDS MAY GUST TO AROUND 25
KNOTS AT TIMES OVER THE OPEN OCEAN WED NIGHT INTO EARLY FRI IN THE
COOL AIR ADVECTION PATTERN. WHILE THE WINDS SHOULD DIMINISH SOME
LATER ON FRI...SCA SEAS MAY LINGER ACROSS THE OUTER-WATERS RIGHT
THROUGH THE WEEKEND. THIS A RESULT OF SWELL FROM A DISTANT LOW
PRESSURE SYSTEM WELL OFFSHORE.
&&
.SURF...
A LINGERING SOUTHERLY SWELL UP TO 7 FT WILL CAUSE A RISK FOR
STRONG RIP CURRENTS AND HIGH SURF PARTICULARLY AT SOUTHERN FACING
BEACHES FOR THE CAPE AND ISLANDS. THE RISK WILL GRADUALLY DIMINISH
DURING THE DAY AS THIS SWELL SUBSIDES. A HIGH SURF ADVISORY HAS
BEEN ISSUED.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...HIGH SURF ADVISORY UNTIL 6 PM EDT THIS EVENING FOR MAZ023-024.
NH...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 8 AM EDT THURSDAY FOR
NHZ011.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT THURSDAY FOR ANZ231-232-
250-254>256.
SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ233-
234-236.
SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR ANZ230-
251.
SMALL CRAFT ADVISORY UNTIL 2 AM EDT THURSDAY FOR ANZ235-237.
&&
$$
SYNOPSIS...BELK/DOODY
NEAR TERM...DOODY
SHORT TERM...DOODY
LONG TERM...FRANK
AVIATION...FRANK/DOODY
MARINE...FRANK/DOODY
TIDES/COASTAL FLOODING...STAFF
AREA FORECAST DISCUSSION
NWS BUFFALO NY
925 AM EDT WED SEP 19 2012
.SYNOPSIS...
COOL HIGH PRESSURE WILL SETTLE INTO THE REGION TODAY WITH A CRISP
FALL LIKE FEEL TO THE DAY. LAKE EFFECT SHOWERS SOUTH AND EAST OF
BOTH LAKES WILL END THROUGH THE MORNING HOURS. A COOL NIGHT IS IN
STORE WEDNESDAY NIGHT BEFORE TEMPERATURES MODERATE THURSDAY AND
FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
MONTAGUE RADAR IS SHOWING A BAND OF LAKE EFFECT RAIN SHOWERS
ORIENTED ALONG THE SOUTHERN SHORE OF LAKE ONTARIO FROM JUST NORTH OF
ROCHESTER EAST ACROSS NORTHERN WAYNE...NORTHERN CAYUGA...AND
SOUTHERN OSWEGO COUNTIES THIS MORNING. THIS BAND HAS FORMED DUE TO
CONVERGENT FLOW ALONG THE SOUTHERN SHORELINE. LAKE INDUCED
INSTABILITY WITH 850MB TEMPS AROUND +1C AND LAKE TEMPS AROUND +20C
IS YIELDING LAKE CLOUDS/RAIN SHOWERS WITH TOPS UP TO 12KFT. THE RGEM
AND HRRR MODELS SHOW THIS BAND PERSISTING INTO THE EARLY AFTERNOON SO
HAVE FEATURES SHOWERS TAPERING OFF AFTER 18Z SOUTHEAST OF LAKE
ONTARIO. SOME EMBEDDED HEAVIER BURSTS OF RAIN WILL OCCUR IN THE MOST
INTENSE AREA OF THE BAND. SEE NOWCASTS FOR MORE SPECIFIC INFO.
FULTON (KFZY) HAS PICKED UP 0.18" OF LAKE EFFECT RAIN SINCE 5AM.
OFF LAKE ERIE THE BUFFALO RADAR IS SHOWING SOME WEAKENING ECHOS
ALONG CATTARAUGUS CREEK AND ANOTHER BAND ORIENTED FROM LONG POINT
SOUTHEAST ACROSS THE LAKE TO SOUTHERN CHAUTAUQUA COUNTY. THESE WEAKER
BANDS WILL BRING SCATTERED LIGHT RAIN SHOWERS TO SECTIONS OF THE
WESTERN SOUTHERN TIER THROUGH THE MORNING THEN MODELS SHOW THE BAND
BREAKING UP BEFORE NOON.
DRIER AIR WILL FILTER IN THROUGH THE BOUNDARY LAYER...AND WITH
DAYTIME MIXING AND THE SFC CONVERGENCE WEAKENING EXPECT THESE LAKE
EFFECT RAIN SHOWERS TO BECOME MORE CELLULAR AND DIMINISH BY THE
EARLY AFTERNOON HOURS.
THIS AFTERNOON WILL FEATURE MOSTLY SUNNY SKIES ACROSS MUCH OF THE
REGION AS SFC HIGH PRESSURE RIDGES INTO THE EASTERN GREAT LAKES
REGION FROM THE OHIO VALLEY. BOTH THE 12Z NAM AND GFS ARE DEPICTING
A NEAR SATURATED LEVEL AROUND 4K FEET LATER THIS MORNING...AND
EXPECTING A DECK OF FAIR WEATHER CU TO FORM FROM THIS LAYER.
TEMPERATURES ALOFT WILL REMAIN COOL AT 850 HPA...RANGING FROM +1 TO
+4C WHICH SUPPORTS COOL AFTERNOON HIGHS IN THE UPPER 50S TO LOWER
60S.
TONIGHT THIS HIGH PRESSURE AT THE SURFACE WILL PUSH TO THE EAST. WINDS WILL
BECOME LIGHT THIS EVENING AND WITH CLEAR SKIES OVERNIGHT
TEMPERATURES WILL DROP TO NEAR TO BELOW SEASONAL NORMS.
WINDS AT THE SURFACE WILL BACK TO SOUTH-SOUTHEASTERLY THROUGH THE
NIGHT FROM WEST TO EAST BEHIND THIS SFC HIGH. COMBINED WITH WAA ALOFT
AND A TIGHTENING SFC GRADIENT BETWEEN THIS SFC HIGH AND A SFC TROUGH
ACROSS THE CENTRAL GREAT LAKES DO NOT BELIEVE FROST WILL BE
WIDESPREAD ACROSS INLAND SOUTHWESTERN NEW YORK. HOWEVER TO THE EAST
WHERE GOOD RADIATIONAL COOLING WILL BE PRESENT FOR SEVERAL
ADDITIONAL HOURS EXPECT TEMPERATURES TO COOL INTO THE MID AND UPPER
30S ACROSS THE PORTIONS OF THE NORTH COUNTRY. FROST COVERAGE WILL BE
GREATEST ACROSS LEWIS COUNTY AND WILL PLACE A FROST ADVISORY
OVERNIGHT FOR THIS COUNTY. FARTHER TO THE NORTH
TEMPERATURES...ESPECIALLY THROUGH THE SAINT LAWRENCE VALLEY AND NEAR
LAKE ONTARIO WILL HOLD HIGH ENOUGH TO PROHIBIT FROST FORMATION.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
AN IMPRESSIVE FULL LATITUDE LONG WAVE TROUGH WILL REMAIN POSITIONED
OVER CENTRAL CANADA AND THE UPPER GREAT LAKES DURING THIS TIME FRAME
WHILE ANOMALOUSLY STRONG RIDGING WILL PERSIST OVER THE YUKON AND THE
CANADIAN MARITIMES. THE POSITION OF THIS HIGH AMPLITUDE PATTERN IS
ONE THAT LAKE EFFECT SNOW LOVERS IN THE BUFFALO AREA DREAM OF...BUT
ONE THAT WE HAVE NOT SEEN FOR QUITE SOME TIME. BUT ALAS...THE
CALENDAR SAYS SEPTEMBER SO WE WILL BE DEALING WITH NEAR TO ABOVE
NORMAL TEMPERATURES WITH SOME RAIN BY THE END OF THE PERIOD.
LOOKING AT THE DETAILS...
FOR THURSDAY...SFC HIGH PRESSURE WILL CONTINUE TO EXIT VIA THE
CANADIAN MARITIMES WHILE A WEAKENING FRONTAL BOUNDARY OVER LOWER
MICHIGAN WILL GET HUNG UP WITHIN THE BROAD SOUTHWESTERLY FLOW. THIS
WILL KEEP THE DOOR OPEN FOR A BEAUTIFUL DAY ACROSS OUR REGION WITH
DOUBLE DIGIT H85 TEMPS SUPPORTING AFTERNOON HIGHS IN THE LOW TO MID
70S (UP 60S TERRAIN).
SINCE THE AXIS OF THE DEEP TROUGH WILL REMAIN OVER THE UPPER GREAT
LAKES THURSDAY NIGHT...THE AFOREMENTIONED COLD FRONT WILL COMPLETELY
WASH OUT OVER OUR REGION WITH ONLY A TEMPORARY INCREASE IN CLOUDS
AND POSSIBLY A FEW SPRINKLES MARKING ITS DYING PRESENCE.
ON FRIDAY...A PAIR OF VIGOROUS SHORTWAVES WILL DROP INTO THE BASE OF
THE ESTABLISHED LONG WAVE TROUGH AND THIS WILL HELP TO GENERATE A
BROAD AND SOMEWHAT NEBULOUS STORM SYSTEM OVER THE UPPER GREAT LAKES.
THE ONLY REASON THAT I ADDRESS THE SFC STORM IS THAT IT WILL
EVENTUALLY DEVELOP A COLD FRONT THAT WILL IMPACT OUR WEATHER FOR THE
WEEKEND. FOR FRIDAY ITSELF THOUGH...WE SHOULD BE ABLE TO SQUEEZE OUT
ONE MORE NICE DAY DESPITE A GRADUAL INCREASE IN CLOUDS. THIS LAST
FULL DAY OF SUMMER WILL APPROPRIATELY FEATURE A TASTE OF SUMMER-LIKE
WARMTH AS MOST AREAS WILL EXPERIENCE AFTERNOON HIGHS IN THE MID TO
UPPER 70S.
UNLIKE THE FRONTAL BOUNDARY THAT WASHED OUT IN THE SOUTHWESTERLY
FLOW EARLIER IN THE WEEK...THE NEWLY FORMED COLD FRONT OVER THE MID
WEST WILL MAKE IT ACROSS OUR REGION DURING THE FIRST PART OF THE
WEEKEND. THE ROBUST SHORTWAVES THAT DROPPED INTO THE TROUGH ON
FRIDAY WILL ROUND THE BASE OF THE TROUGH FRIDAY NIGHT AND
SATURDAY...AND THIS WILL BE MORE THAN ENOUGH TO PUSH A STRENGTHENING
FRONTAL BOUNDARY ACROSS OUR REGION TO NEW ENGLAND. IN FACT...BOTH
THE NAM AND GFS SUGGEST THAT A STRONG 50KT LOW LEVEL JET WILL BE IN
PLACE FRIDAY NIGHT...BUT A STRONG INVERSION BASED ARND 1500 FT
SHOULD KEEP THESE WINDS FROM MIXING TO THE SFC. THE EXCEPTION WILL
BE ACROSS THE HIGHER TERRAIN OF THE SRN TIER WHERE GUSTS OVER 30
HAVE BEEN ADDED TO THE GRIDS. OTHERWISE...SHOWERS WILL BREAK OUT
OVER THE WESTERN COUNTIES AHEAD OF THE SLOW MOVING FRONT FRIDAY
EVENING...WITH SHOWERS ANTICIPATED REGIONWIDE LATE FRIDAY NIGHT AND
SATURDAY. WILL USE HIGH CHC POPS TO COVER THIS POTENTIAL.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
A HIGH AMPLITUDE PATTERN...FEATURING A BROAD FULL LATITUDE TROUGH
OVER HUDSON BAY AND THE UPPER GREAT LAKES...WILL CONTINUE TO
DOMINATE THE MAJORITY OF NORTH AMERICA DURING THIS PERIOD. SINCE THE
AXIS OF THIS DEEP TROUGH WILL BE A COUPLE HUNDRED MILES FURTHER EAST
THAN IT WAS EARLIER IN THE WEEK...WE CAN ANTICIPATE COOLER WEATHER
WITH BELOW NORMAL TEMPERATURES THROUGH AT LEAST MONDAY.
IN TERMS OF PRECIPITATION...THE BASE OF A SHORTWAVE TROUGH WILL
ROTATE ACROSS THE LOWER GREAT LAKES ON SUNDAY TO PRODUCE SCATTERED
SHOWERS ACROSS THE REGION. THE SHOWERS WILL BE ENHANCED BY CHILLY
H85 TEMPS OF 2C CROSSING LAKES ERIE AND PARTICULARLY LK ONTARIO.
WILL PLAY UP THIS LAKE ASSISTANCE BY USING 50 POPS ACROSS THE
EASTERN LAKE ONTARIO REGION.
EXPANSIVE SFC BASED HIGH PRESSURE OVER THE LOWER OHIO VALLEY SUNDAY
NIGHT WILL THEN BUILD EAST ACROSS THE OHIO VALLEY ON MONDAY BEFORE
MAKING ITS WAY ACROSS THE MIDDLE ATLANTIC STATES ON TUESDAY. THIS
WILL PROMOTE A RETURN TO GENERALLY FAIR WEATHER TO OUR REGION WITH A
DAY TO DAY WARMING TREND. AFTERNOON TEMPERATURES THAT WILL BE CLOSE
TO 60 ON SUNDAY WILL BE CLOSER TO 70 IN MANY AREAS ON TUESDAY.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
AT 12Z MAINLY VFR FLIGHT CONDITIONS WERE FOUND THIS MORNING...WITH
THE EXCEPTION BEING DOWNWIND OF BOTH LAKES WHERE SOME MVFR
CONDITIONS IN LAKE EFFECT RAIN SHOWERS IS POSSIBLE THROUGH MID
MORNING. THE BAND OF SHOWERS OFF LAKE ONTARIO IS NOW THE DOMINATE
BAND...WITH THE SHOWERS OFF LAKE ERIE NOW DIMINISHING. STILL WILL
CARRY A VCSH FOR KJHW FOR AN HOUR THIS MORNING. FOR THE BAND OFF
LAKE ONTARIO IT WILL REMAIN TO THE SOUTH AND EAST OF THE LAKE AND
DIMINISH THROUGH THE MORNING HOURS.
OTHERWISE EXPECT VFR FLIGHT CONDITIONS TO PREVAIL THROUGH THE
REMAINDER OF THE TAF PERIOD AS HIGH PRESSURE AT THE SFC QUICKLY
PASSES THROUGH THE REGION. WINDS WILL GO LIGHT AND VARIABLE TONIGHT
BEFORE BACKING TO SOUTHERLY LATE FROM WEST TO EAST ACROSS THE
REGION.
OUTLOOK...
THURSDAY AND FRIDAY...MAINLY VFR.
SATURDAY AND SUNDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
&&
.MARINE...
SMALL CRAFT ADVISORIES WILL CONTINUE ON BOTH LAKES TODAY WITH A COOL
AIRMASS ALOFT PASSING OVER THE WARM WATERS OF BOTH LAKES. THOUGH
WINDS WILL SUBSIDE TO LESS THAN 20 KNOTS EARLY THIS MORNING...WAVES
WILL CONTINUE AT OR ABOVE SCA LEVELS TO START THE MORNING. EXPECT
THESE WAVES TO DROP BELOW SCA LATER THIS MORNING ON LAKE ERIE AND
EARLY THIS AFTERNOON ON LAKE ONTARIO. WITH THE COOL AIR ALOFT...A
CHANCE FOR WATERSPOUTS ON THE LAKES CONTINUES THROUGH THE MORNING
HOURS. IN ADDITION ISOLATED BANDS OF LAKE EFFECT RAIN SHOWERS WILL
BRING BRIEF HEAVY DOWNPOURS THROUGH THE MORNING.
WIND AND WAVES WILL THEN SUBSIDE LATER WEDNESDAY AS HIGH PRESSURE
RIDGES NORTHEAST FROM THE OHIO VALLEY. A SOUTHERLY BREEZE ON
THURSDAY AHEAD OF THE NEXT SFC TROUGH WILL INCREASE WAVES
AGAIN...THOUGH THE HIGHEST WAVES WILL REMAIN ON THE NORTHERN HALF OF
BOTH LAKES.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...FROST ADVISORY FROM 2 AM TO 8 AM EDT THURSDAY FOR NYZ008.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR LEZ040-
041.
SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON
FOR LOZ043>045.
SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR
LOZ042.
&&
$$
SYNOPSIS...THOMAS
NEAR TERM...SMITH/THOMAS
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...THOMAS
MARINE...SMITH/THOMAS
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
306 PM CDT WED SEP 19 2012
.SYNOPSIS...
12Z UA ANALYSIS HAD A STRONG UPPER LOW EAST OF LAKE WINNIPEG. THE
850MB COLD FRONT RAN FROM THE ARROW HEAD OF MINNESOTA TO EASTERN
WYOMING. THE 850MB WARM FRONT RAN SOUTH ROUGHLY ALONG THE
MISSISSIPPI RIVER. STRONG CAA WAS OCCURRING BEHIND THE UPPER FRONT
WITH 850MB TEMPERATURES QUICKLY DROPPING INTO THE SINGLE DIGITS AT
THE INTERNATIONAL BORDER. SATELLITE TRENDS THROUGH MID AFTERNOON
SHOW RAPID DEVELOPMENT OF CLOUDS ALONG THE SFC COLD FRONT FROM
SOUTHEAST MINNESOTA INTO NORTHWEST IOWA. RADARS WERE SHOWING VIRGA
DEVELOPING FROM NORTHEAST IOWA INTO WESTERN WISCONSIN.
18Z SFC ANALYSIS HAD THE COLD FRONT RUNNING FROM THE KDLH AREA TO
SOUTHEAST COLORADO. A NARROW TONGUE OF LOW AND MID 50 DEW POINTS RAN
FROM THE SOUTHERN PLAINS INTO WESTERN IOWA. DEW POINTS IN THE 40S
WERE COMMON ACROSS MUCH OF THE MIDWEST AND WESTERN GREAT LAKES. DEW
POINTS IN THE 30S WERE ACROSS THE NORTHERN PLAINS AND GREAT LAKES.
&&
.SHORT TERM...TONIGHT AND THURSDAY...
BASED ON RADAR TRENDS...VIRGA IS BECOMING MORE PRONOUNCED FROM THE
CU FIELD THAT IS DEVELOPING ALONG THE COLD FRONT AND PRE-FRONTAL
TROF. RAP TRENDS CONTINUE TO SHOW MID LEVEL FORCING WILL INCREASE
THROUGH THE REMAINDER OF THE AFTERNOON WITH IT MAXIMIZING RIGHT
AROUND 00Z. FCST SOUNDINGS INDICATE CLOUD BASES IN THE 7-10 KFT AGL
RANGE SO THE VIRGA SHOULD BE QUITE OBVIOUS LATE THIS AFTERNOON IN
THE NORTHWEST PART OF THE CWFA WITH IT POTENTIALLY COMING FROM RADAR
RETURNS OF 30 DBZ OR HIGHER. EVENTUALLY...PRECIP WILL REACH THE
GROUND SO THE SCHC/CHC FOR LATE THIS AFTERNOON STILL LOOKS OKAY.
THE FRONT WILL SWEEP ACROSS THE CWFA DURING THE EVENING HOURS. AS
THE FORCING REACHES A MAXIMUM EARLY THIS EVENING THE POTENTIAL FOR A
COUPLE OF TSRA RIGHT ALONG THE FRONT IS POSSIBLE. HOWEVER...THE
NUMBER OF TSRA SHOULD BE NO MORE THAN A HANDFUL. THERE SHOULD STILL
BE CONSIDERABLE VIRGA INTO THE EARLY EVENING WITH THE MEASURABLE
RAIN LIKELY CONFINED TO A NARROW BAND ALONG THE FRONT.
BY MID EVENING THE RAIN SHOULD BE EAST OF THE MISSISSIPPI AND EXIT
THE AREA BY MIDNIGHT. STRONG SUBSIDENCE BEHIND THE SHORTWAVE SHOULD
RESULT IN SKIES CLEARING FAIRLY QUICKLY. AS THE HIGH BUILDS IN WINDS
SHOULD BECOME LIGHT WHICH WILL ALLOW TEMPERATURES TO DROP AS THE
SKIES CLEAR. THE WAPSI VALLEY ALONG WITH FAVORED COLD AREAS IN THE
NORTHERN CWFA SHOULD SEE THE COOLEST TEMPERATURES BY SUNRISE
THURSDAY.
ON THURSDAY QUIET AND DRY CONDITIONS WITH COOLER TEMPERATURES WILL
BE SEEN AS HIGH PRESSURE QUICKLY MOVES ACROSS THE AREA. ..08..
.LONG TERM...THURSDAY NIGHT THROUGH NEXT WEDNESDAY...
THE EXTENDED FORECAST REMAINS VERY ACTIVE WITH MANY PASSING STRONG
SHORT WAVES ROUNDING THE BASE OF A STRONG UPPER AIR TROF IN THE
GREAT LAKES. THIS RESULTS IN SEVERAL DAYS OF FORECAST RAIN
CHANCES...WHICH ARE ALL LOW IN CONFIDENCE DUE TO THE CHANGEABLE
FORCING FORECAST FROM RUN TO RUN...AND MODEL TO MODEL. MUCH HIGHER
CONFIDENCE IS THAT WE WILL SEE A VERY COOL PERIOD OF DAYS...FOLLOWED
BY MODERATE WARMING. BY THURSDAY NIGHT THE PATTERN WILL ALREADY BE
ESTABLISHED...WITH THE 1ST OF SEVERAL WAVES ALREADY APPROACHING.
THIS SHOULD GENERATE WARM ADVECTION THEN STRONGLY FORCED COLD
FRONTAL SHOWERS FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING.
RAINFALL AMOUNTS SHOULD BE LIGHT...BUT COULD BE UP TO 0.25 IN
SPOTS...ESPECIALLY NORTHEAST. FRIDAY LOOKS TO BE BLUSTERY UNDER
THE CLOUD COVER...THEN AFTER SEVERAL HOURS OF EASING EVENING
WINDS...AND CLEAR SKIES...WE WILL SEE A VERY STRONG UPPER WAVE DROP
SOUTH. THIS FRONT WILL SWEEP THROUGH EARLY SATURDAY...RESULTING IN
GUSTY NORTH WINDS...AND VERY STRONG COLD ADVECTION. SATURDAYS
TEMPERATURES FORECAST WITH HIGHS IN THE MID 50S NORTH TO LOWER 60S
SOUTH SEEMS OPTIMISTIC DESPITE IT BEING LOWER THAN MOST GUIDANCE.
SHOULD RAIN LINGER INTO THE DAY FOR MORE THAN A FEW HOURS...WE COULD
SEE HIGHS IN THE 40S...WITH PLENTY OF WIND. SHOULD SUNSHINE BECOME
WIDESPREAD SATURDAY AFTERNOON...RESULTING IN DEEPER MIXING...A WIND
ADVISORY IS NOT OUT OF THE QUESTION.
SATURDAY NIGHT...AND SUNDAY NIGHT...A FROST OR FREEZE IS POSSIBLE.
THIS PAST MORNING...WITH ONLY 1/2 OF A NIGHT SEEING CLEAR SKIES...WE
HIT THE MID 30S WITH 850MB TEMPERATURES OF 3 DEGREE. BOTH UPCOMING
NIGHTS THIS WEEKEND SHOULD SEE 850MB TEMPS OF +1 TO -2 DEGREES.
WHILE WINDS MAY NOT BE AS LIGHT...THIS SHOULD STILL RESULT IN COOLER
NIGHTS THAN LAST NIGHT. FOR NOW...UNTIL WE ARE CERTAIN...WILL KEEP
LOWS OF MID 30S FORECAST. SUNDAY ITSELF SHOULD BE A PLEASANT BUT
COOL DAY IN THE UPPER 50S TO LOWER 60S...AS WIND SHOULD BE LESS OF
AN ISSUE.
MONDAY INTO TUESDAY...MODERATING TEMPERATURES AND A DEVELOPING
SOUTHERLY FLOW SHOULD ALLOW FOR TEMPERATURES TO RETURN TO THE UPPER
60S MONDAY...AND MID 70S TUESDAY. TUESDAY INTO WEDNESDAY...MOISTURE
ADVECTION OVER A DEVELOPING WARM FRONT NEARBY SHOULD ALLOW FOR RAIN
POSSIBILITIES...AND POSSIBLE CONVECTION.
ERVIN
&&
.AVIATION... /ISSUED 1225 PM CDT WED SEP 19 2012/
DEEP MIXING IS ALLOWING WINDS TO GUST OVR 30 KTS. MAINLY VFR WX
IS EXPECTED THROUGH 00Z/21 IN SPITE OF A COLD FRONT MOVING THROUGH
IN THE 23Z/19 TO 04Z/20 TIME FRAME. WINDS WILL DIMINISH AHEAD OF
THE FRONT LATE THIS AFTERNOON AND WITH SUNSET WITH VFR CIGS AND A
WIND SHIFT INDICATING FRONTAL PASSAGE. KDBQ HAS THE BEST CHANCE AT
SEEING A SHRA WITH THE POTENTIAL OF BRIEF MVFR CONDITIONS. HIGH
PRESSURE BUILDING IN LATE TONIGHT AND THURSDAY WILL RESULT IN
LOWER SUSTAINED WINDS. ..08..
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
320 PM CDT WED SEP 19 2012
.DISCUSSION...
CDFNT NOW PUSHING INTO WC WI WITH AIRMASS STILL FAIRLY WARM BEHIND
IT WITH SUN ACROSS MUCH OF S MN. DEEP MIXING HAS ALLOWED GUSTY NW
WINDS AND DRY AIR TO MIX DOWN IN WAKE OF FRONT. WILL LET WIND ADVY
RUN UNTIL SCHD 00Z EXPIRATION TIME...OCCASIONALLY GETTING
SUSTAINED WINDS NEAR 30 MPH. A COUPLE OF AREAS OF PCPN CURRENTLY
ONGOING. ONE IS ACROSS N MN INTO NW WI ASSOCIATED WITH VORT MAX
DROPPING SE ACROSS N MN. ANOTHER WEAKER AREA OF SHOWERS HAS BEEN
TRYING TO DEVELOP ACROSS CENTRAL WI...NOW JUST E OF EAU AHEAD OF
CDFNT. MOST PCPN SHOULD END ACROSS OUR AREA BY 00Z...ASIDE FROM A
SMALL CHANCE IN A FEW OF OUR WI COUNTIES.
DURING THE NEXT FEW DAYS WE REMAIN IN NW FLOW WITH HEIGHTS
DROPPING INTO SATURDAY AS SUCCESSION OF SHORTWAVES CONTINUE TO
CARVE OUT DEEPER AND COOLER UPPER TROF. TIMING OF SHORTWAVES AND
ASSOCIATED CDFNTS COMING THRU WILL MAKE TEMPERATURE FORECASTS A
BIT OF A CHALLENGE.
FIRST ONE DROPS OUT OF N MN ACROSS OUR AREA THURSDAY EVENING/NIGHT
BRINGING A FEW SHOWERS. WINDS BACK AHEAD OF THIS FRONT WICH WILL
GIVE SC MN SHOT OF GETTING TEMPS NEAR 70 TOMORROW.
STRONGER TROF COMES DOWN ON FRIDAY NIGHT WHICH SHOULD GIVE A BIT
MORE COVERAGE OF PCPN. 500 MB TEMPS DROP TO B30 WITH THIS SYSTEM
GIVING SOME INDICATION OF COLD AIR SUPPLY. SOME OF THE TRADITIONAL
THICKNESS PARAMETERS WOULD INDICATE A CHANCE OF SNOW -SN MIXING IN
FRIDAY NIGHT/EARLY SATURDAY...BUT NAM/GFS/ECMWF ALL KEEP 925 MB
TEMPS WARM ENUF TO KEEP PCPN AS RAIN. WITH COLD AIR ALOFT WOULD
NOT BE SURPRISED TO SEE SLEET FROM ANY AFTN CONVECTIVE SHOWERS
WHICH MIGHT DEVELOP.
WEATHER SHUD REMAIN UNSETTLED ENUF THROUGH SATURDAY TO PREVENT ANY
SIGNIFICANT FROST...BUT SUNDAY MORNING MAY BE ANOTHER STORY AS
COLD HIGH PRESSURE (AROUND 1025 MB) BUILDS ACROSS AREA.
WARMING TREND THEN BEGINNING EARLY IN THE WEEK AS COLD UPPER TROF
OPENS UP AND FLOW BECOMES MORE ZONAL.
&&
.AVIATION.../18Z TAF ISSUANCE/
COLD FRONT CURRENTLY PUSHING THROUGH THE TWIN CITIES METRO...WITH
NW WINDS PICKING UP IN STRENGTH BEHIND THE FRONT. THIS FRONT WILL
CLEAR EAU AROUND 20Z...MEANING ANY POTENTIAL PRE-FRONTAL
CONVECTION WILL OCCUR SE OF ALL MPX TERMINALS. EXTENSIVE STRATOCU
FIELD WITH EMBEDDED SHRA UNDERNEATH MID LEVEL COLD POCKET NOW
SLIDING SE OUT OF NRN MN. WILL PROVIDE BKN CIGS BTWN 050 AND 070
FOR ALL BUT RWF THIS AFTERNOON. HRRR REFLECTIVITY FORECAST HAS
BEEN TRENDING LESS AND LESS WITH CONVECTIVE SHRA ACROSS THE MPX
AREA THIS AFTERNOON...SO LIMITED ANY PRECIP MENTION TO VCSH AT ALL
LOCATIONS. STILL LOOKS LIKE WI TERMINALS HAVE THE BEST CHANCE AT
SEEING A SHOWER THIS AFTERNOON. SEEING SOME GUSTS OVER 30 KTS IN
WRN MN...SO GOING TAFS LOOK TO CAPTURE AFTERNOON WIND SPEEDS WELL.
WINDS WILL COME DOWN UNDER 10KTS TONIGHT...BUT GUSTS TO 20 KTS
LOOK TO RETURN AS MIXING PICKS UP THU MORNING. WITH STRONG NW JET
OVERHEAD...WILL BE A FAIRLY CLOUDY PERIOD...WITH PERSISTENT BOUTS
OF MID AND HIGH CLOUDS EXPECTED THROUGH THE PERIOD...THOUGH NO
OTHER PRECIP INDUCING WAVES LOOK TO COME DOWN UNTIL THU EVENING.
KMSP...COLD FRONT WILL PASS THROUGH THE FIELD AROUND 19Z...WITH
SOME GUSTS OVER 25 KTS EXPECTED THIS AFTERNOON. DOWNPLAYED PRECIP
MENTION GIVEN DRY GFS AND INCREASINGLY DRY HRRR...THOUGH WINDOW
FOR PRECIP STILL LOOKS TO BE CENTERED AROUND 00Z. CLOUDS TOMORROW
LOOK TO START OUT AROUND 200 AND DESCEND TOWARD 080 BY THE END OF
THE TAF. ANY PRECIP WILL COME JUST AFTER THIS TAF PERIOD.
/OUTLOOK FOR KMSP/
.FRIDAY...VFR. CHC MORNING SHRA. WINDS NW 10-15 KTS.
.SATURDAY...MVFR POSSIBLE WITH CHC SHRA. WINDS NW 12-18 KTS.
.SUNDAY...VFR. WINDS W 5-10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR BLUE EARTH-BROWN-
CHIPPEWA-DOUGLAS-KANDIYOHI-LAC QUI PARLE-MCLEOD-MEEKER-
NICOLLET-POPE-REDWOOD-RENVILLE-SIBLEY-STEARNS-STEVENS-SWIFT-
TODD-WATONWAN-YELLOW MEDICINE.
WI...NONE.
&&
$$
BAP/MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
123 PM CDT WED SEP 19 2012
.UPDATE...
18Z AVIATION DISCUSSION ADDED BELOW.
&&
.DISCUSSION...
TODAY WILL BE WINDY AND COOL AS THE FIRST ROUND OF COLD AIR STREAMS
IN FROM CANADA. TEMPERATURES WILL REMAIN WELL BELOW THE SEASONAL
AVERAGE THROUGH THE END OF THE WEEK. ASIDE FROM A BRIEF WARM DAY
ON MONDAY...THE NEXT SEVERAL DAYS WILL BE CHARACTERIZED BY
CLOUDY...BREEZY...AND COOL CONDITIONS WITH PERIODIC CHANCES FOR
LIGHT RAINFALL.
TODAY...EARLY MORNING WATER VAPOR IMAGERY IDENTIFIED A POTENT
SHORTWAVE OVER NORTH DAKOTA. THIS UPPER LEVEL WAVE WAS RESPONSIBLE
FOR A 996MB SURFACE LOW OVER LAKE WINNIPEG...WITH A COLD FRONT
EXTENDING SOUTHWARD THROUGH THE EASTERN DAKOTAS. LATER TODAY AN AREA
OF PRECIP WILL DEVELOP OVER NORTHERN MN/WI CLOSER TO THE BETTER
UPPER LEVEL FORCING. MEANWHILE...DIABATIC HEATING AND COLD AIR
ADVECTION IN THE LOWER LEVELS BEHIND THE AFOREMENTIONED SURFACE COLD
FRONT WILL DESTABILIZE THE BOUNDARY LAYER AND ALLOW STRONG WINDS TO
MIX DOWN TO THE SURFACE. FORECAST SOUNDINGS SHOW POTENTIAL WINDS OF
25 TO 30KTS BY THIS AFTERNOON...ESPECIALLY ALONG THE MINNESOTA RIVER
VALLEY. THEREFORE HAVE ISSUED A WIND ADVISORY FOR THIS AREA.
FORECAST SOUNDINGS ALSO SHOW A CLOUD LAYER AROUND 5000FT AGL WHICH
SHOULD ACT TO MODERATE TEMPERATURES WHICH IN TURN WILL KEEP HUMIDITY
LEVELS FROM BOTTOMING OUT THIS AFTERNOON. BASED ON THESE HIGHER RH
VALUES...HAVE DECIDED TO CANCEL THE FIRE WEATHER WATCH AND DID NOT
UPGRADE TO A RED FLAG WARNING. CONDITIONS WILL STILL BE DRY WITH
STRONG WINDS...BUT SHOULD REMAIN BELOW RED FLAG CRITERIA ACROSS THE
WEST. FURTHER EAST...THE COMBINATION OF THE UPPER LEVEL DYNAMICS AND
MID LEVEL INSTABILITY SHOULD BE ENOUGH TO SPARK A FEW SHOWERS WITH
EVEN SOME ISOLATED THUNDER OVER EASTERN MN AND WESTERN WI. THIS
PRECIP SHOULD TAPER OFF BY SUNSET...WITH SKIES CLEARING OUT
OVERNIGHT.
THURSDAY THROUGH TUESDAY...A DEEP UPPER LEVEL TROUGH WILL PERSIST
ACROSS CENTRAL CANADA AND THE UPPER MIDWEST. EMBEDDED SHORTWAVES
WITHIN THIS CYCLONIC FLOW WILL TRACK ACROSS THE REGION AND BRING
COOL RAIN SHOWERS...NAMELY THURSDAY NIGHT AND FRIDAY NIGHT.
THEREFORE NOT EXPECTING MUCH IN THE WAY OF DIURNAL TEMPERATURE
SWINGS DURING THIS TIME PERIOD. NORTHWEST WINDS WILL ALSO PREVAIL
WITH BLUSTERY CONDITIONS ACTING TO ERASE ANY MEMORY OF THE RECENT
WARM SUMMER. FINALLY BY SUNDAY THE LONGWAVE TROUGH WILL HEAD TOWARDS
NEW ENGLAND WITH H850 SOUTHWEST FLOW BRINGING WARMER TEMPERATURES
FOR MONDAY...WHICH MAY LINGER THROUGH THE MIDDLE OVER NEXT WEEK.
THEREFORE HAVE BUMPED UP TEMPERATURES ON MONDAY A FEW DEGREES FROM
THE LONG RANGE CONSENSUS.
&&
.AVIATION.../18Z TAF ISSUANCE/
COLD FRONT CURRENTLY PUSHING THROUGH THE TWIN CITIES METRO...WITH
NW WINDS PICKING UP IN STRENGTH BEHIND THE FRONT. THIS FRONT WILL
CLEAR EAU AROUND 20Z...MEANING ANY POTENTIAL PRE-FRONTAL
CONVECTION WILL OCCUR SE OF ALL MPX TERMINALS. EXTENSIVE STRATOCU
FIELD WITH EMBEDDED SHRA UNDERNEATH MID LEVEL COLD POCKET NOW
SLIDING SE OUT OF NRN MN. WILL PROVIDE BKN CIGS BTWN 050 AND 070
FOR ALL BUT RWF THIS AFTERNOON. HRRR REFLECTIVITY FORECAST HAS
BEEN TRENDING LESS AND LESS WITH CONVECTIVE SHRA ACROSS THE MPX
AREA THIS AFTERNOON...SO LIMITED ANY PRECIP MENTION TO VCSH AT ALL
LOCATIONS. STILL LOOKS LIKE WI TERMINALS HAVE THE BEST CHANCE AT
SEEING A SHOWER THIS AFTERNOON. SEEING SOME GUSTS OVER 30 KTS IN
WRN MN...SO GOING TAFS LOOK TO CAPTURE AFTERNOON WIND SPEEDS WELL.
WINDS WILL COME DOWN UNDER 10KTS TONIGHT...BUT GUSTS TO 20 KTS
LOOK TO RETURN AS MIXING PICKS UP THU MORNING. WITH STRONG NW JET
OVERHEAD...WILL BE A FAIRLY CLOUDY PERIOD...WITH PERSISTENT BOUTS
OF MID AND HIGH CLOUDS EXPECTED THROUGH THE PERIOD...THOUGH NO
OTHER PRECIP INDUCING WAVES LOOK TO COME DOWN UNTIL THU EVENING.
KMSP...COLD FRONT WILL PASS THROUGH THE FIELD AROUND 19Z...WITH
SOME GUSTS OVER 25 KTS EXPECTED THIS AFTERNOON. DOWNPLAYED PRECIP
MENTION GIVEN DRY GFS AND INCREASINGLY DRY HRRR...THOUGH WINDOW
FOR PRECIP STILL LOOKS TO BE CENTERED AROUND 00Z. CLOUDS TOMORROW
LOOK TO START OUT AROUND 200 AND DESCEND TOWARD 080 BY THE END OF
THE TAF. ANY PRECIP WILL COME JUST AFTER THIS TAF PERIOD.
/OUTLOOK FOR KMSP/
.FRIDAY...VFR. CHC MORNING SHRA. WINDS NW 10-15 KTS.
.SATURDAY...MVFR POSSIBLE WITH CHC SHRA. WINDS NW 12-18 KTS.
.SUNDAY...VFR. WINDS W 5-10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR BLUE EARTH-BROWN-
CHIPPEWA-DOUGLAS-KANDIYOHI-LAC QUI PARLE-MCLEOD-MEEKER-
NICOLLET-POPE-REDWOOD-RENVILLE-SIBLEY-STEARNS-STEVENS-SWIFT-
TODD-WATONWAN-YELLOW MEDICINE.
WI...NONE.
&&
$$
JRB/MPG
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
201 PM EDT WED SEP 19 2012
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH FRIDAY. A COLD FRONT
WILL APPROACH THE MID ATLANTIC ON SATURDAY...WHICH WILL BRING A
CHANCE OF SCATTERED SHOWERS FOR THIS WEEKEND. HIGH PRESSURE WILL
RETURN BY MONDAY TO BRING DRIER AND SIGNIFICANTLY COOLER WEATHER.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1200 PM EDT WEDNESDAY...
HIGH TEMPERATURES WERE BUMPED UP A DEGREE OR TWO...AS SKIES HAVE
ALMOST CLEARED WEST OF THE BLUE RIDGE...AND CLOUD COVER OVER THE
PIEDMONT HAS BEGUN TO SCATTER DURING THE PAST COUPLE HOURS. WIND
SPEEDS WERE BUMPED SLIGHTLY UPWARD FOR THE NORTHERLY FLOW TAKING
SHAPE. ALTHOUGH THE RECENT NAM AND RAP MODELS SHOW A TINY AMOUNT
OF PRECIPITATION ALONG THE NORTHWEST NORTH CAROLINA MOUNTAINS DUE
TO UPSLOPE FLOW...THERE IS LITTLE IF ANY CHANCE OF SIGNIFICANT
MOISTURE DUE TO THE DRY AIR MASS SETTLING OVER THE MID ATLANTIC.
AS OF 1000 AM EDT WEDNESDAY...
CLOUD COVER STILL LINGERS OVER THE PIEDMONT FROM THE DEPARTING
COLD FRONT. HOWEVER...SKIES ARE QUICKLY CLEARING WEST OF THE BLUE
RIDGE. THE 12Z RNK SOUNDING REVEALS A CONSIDERABLE DROP IN
PRECIPITABLE WATER...FROM 1.31 INCHES LAST NIGHT TO ONLY 0.54
INCHES THIS MORNING. HIGH PRESSURE WILL CONTINUE TO BUILD OVERHEAD
THIS AFTERNOON. HIGH TEMPERATURES FOR TODAY STILL APPEAR ON
TARGET...AND NO OTHER SIGNIFICANT CHANGES WERE MADE.
AS OF 345 AM EDT WEDNESDAY...
THE COLD FRONT HAS EXITED EAST OF OUR AREA THIS MORNING...AND
INFRARED SATELLITE IMAGERY INDICATES THAT SKIES ARE CLEARING FOR
AREAS ALONG AND WEST OF THE BLUE RIDGE...WHILE LOW CLOUDS LINGER
ACROSS THE PIEDMONTS. AS DRIER AIR CONTINUES TO FILTER IN FROM THE
NORTHWEST THIS MORNING...EXPECT THE CLEARING TO CONTINUE...WITH
MOSTLY CLEAR SKIES EXPECTED ACROSS ALL BUT OUR FAR WESTERN
RIDGELINES DURING THE AFTERNOON...WHERE PARTLY CLOUDY SKIES WILL
PERSIST.
WITH BROAD UPPER LEVEL TROUGHING SITUATED ACROSS THE EASTERN
STATES FOR TODAY...TEMPERATURES WILL RANGE ANYWHERE FROM 7 TO 10
DEGREES BELOW NORMAL FOR THE SECOND HALF OF SEPTEMBER...BUT WILL
STILL REMAIN ON THE MILD SIDE. EXPECT HIGHS FOR TODAY TO RANGE
FROM THE LOW TO MID 60S ACROSS THE MOUNTAINS...TO THE LOW 70S
ACROSS THE PIEDMONTS. STUCK PRETTY CLOSE TO MAV GUIDANCE FOR
HIGHS...BUT WENT A DEGREE OR TWO BELOW MOST AREAS TO ACCOUNT FOR
MOIST SOIL CONDITIONS FROM TUESDAYS WIDESPREAD RAINFALL.
LOOKING INTO TONIGHT...HIGH PRESSURE WILL BEGIN TO SETTLE ALONG
THE APPALACHIAN SPINE...WHICH WILL MAKE FOR LIGHT WINDS ACROSS THE
AREA...AND MORE INDICATIONS THAT AUTUMN IS ALMOST OFFICIALLY UPON
US. EXPECT OVERNIGHT LOW TEMPERATURES TO RANGE FROM THE LOW TO MID
40S ACROSS THE MOUNTAINS...A FEW UPPER 30S ALONG THE HIGHER
RIDGELINES...TO THE LOW 50S ACROSS THE NORTH CAROLINA PIEDMONT.
WITH LIGHT WINDS EXPECTED...MOSTLY CLEAR SKIES AND MOIST SOILS...
EXPECT PATCHY FOG WILL DEVELOP MAINLY ACROSS THE MOUNTAINS AND
ESPECIALLY IN THE RIVER VALLEYS. MAY STILL HAVE ENOUGH
NORTHEASTERLY WIND FLOW IN THE PIEDMONTS TO KEEP A LID ON
WIDESPREAD FOG FORMATION...BUT STILL EXPECT TO SEE LOCALIZED DROPS
IN VISIBILITY FURTHER EAST BY SUNRISE THURSDAY MORNING.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
AS OF 245 AM EDT WEDNESDAY...
ON THURSDAY...THE AXIS OF SURFACE HIGH PRESSURE WILL EXTENT FROM THE
PARENT HIGH OVER NEW ENGLAND SOUTHWEST ALONG THE LEE OF THE
APPALACHIANS. CONCURRENTLY...AN UPPER LOW WILL BE JUST NORTH OF LAKE
SUPERIOR WITH ITS ASSOCIATED TROUGH AXIS EXTENDING SOUTH INTO THE
MID-MISSISSIPPI VALLEY. AS WE PROGRESS INTO THE START OF THE
UPCOMING WEEKEND...THE LOW/TROUGH IS EXPECTED TO AMPLIFY. THIS WILL
HAVE THE EFFECT OF TRENDING ANY ASSOCIATED COLD FRONTS SLOWER IN
THEIR APPROACH OF THE REGION. SOUTHWEST FLOW WILL BE ON THE INCREASE
ACROSS THE AREA AS THE CENTER OF THE SURFACE HIGH SHIFTS EAST AND
FLOW IN ADVANCE OF THE DEEPENING LOW INCREASES. ANTICIPATE DRY
WEATHER WITH A TREND FOR MODERATING TEMPERATURES THURSDAY AND
FRIDAY.
BY SATURDAY...TEMPERATURES WILL CONTINUE TO TREND MILDER.
HOWEVER...BY THE AFTERNOON...EXPECT INCREASING CLOUDS AND ISOLATED
TO SCATTERED SHOWERS ACROSS THE MOUNTAINS AS A COLD FRONT
APPROACHES. THE FRONT WILL CROSS THE REGION LATE IN THE AFTERNOON
INTO THE EVENING HOURS ON SATURDAY. THE BEST INSTABILITY LOOKS TO
REMAIN CLOSER TO THE COAST...SO WILL ONLY MENTION SHOWERS AT THIS
TIME.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 330 AM EDT WEDNESDAY...
BY SUNDAY...THE MODEL GUIDANCE DIVERGES SIGNIFICANTLY. THE GFS
BECOMES VERY PROGRESSIVE IN PUSHING THE UPPER LEVEL TROUGH
EASTWARD...WHICH WOULD CLEAR THE MID ATLANTIC AND PROVIDE DRIER
CONDITIONS. MEANWHILE...THE ECMWF HOLDS THE TROUGH BACK OVER THE
GREAT LAKES...AND BRINGS A SECOND SHORTWAVE TROUGH WITH A MORE
POTENT COLD FRONT THAT WOULD PROVIDE A BETTER CHANCE OF SHOWERS.
GIVEN THE PROGRESSIVE BIAS OF THE GFS...AND THE FACT THAT DEEP
UPPER LEVEL TROUGHS PROPAGATE AT A CONSIDERABLY SLOW RATE...ALL
THE FORECAST GRIDS WERE ADJUSTED TOWARD THE ECMWF SOLUTION. THE
UPPER LEVEL TROUGH WILL EVENTUALLY MOVE EASTWARD BY SUNDAY NIGHT.
A LARGE AREA OF HIGH PRESSURE WILL BUILD IN ON MONDAY AND PERSIST
THROUGH THE FIRST HALF OF NEXT WEEK. NORTHWEST WINDS BEHIND THE
DEPARTING COLD FRONT SHOULD PROVIDE DECENT COLD AIR ADVECTION. AS
DEWPOINTS FALL CONSIDERABLY...TEMPERATURES WILL ALSO DROP TO MAKE IT
FEEL LIKE AUTUMN...WITH HIGHS ONLY REACHING THE LOWER 60S TO LOWER
70S ON MONDAY. CALM WINDS AND MAINLY CLEAR SKIES DUE TO HIGH
PRESSURE OVERHEAD SHOULD ALLOW SUFFICIENT DECOUPLING IN THE LOWER
TROPOSPHERE DURING MONDAY NIGHT...WHICH WILL CAUSE LOWS TO PLUMMET
INTO THE UPPER 30S TO MID 40S BY TUESDAY MORNING.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AS OF 200 PM EDT WEDNESDAY...
CLOUD COVER HAS DISSIPATED ENOUGH TO ALLOW VFR CONDITIONS FOR THE
REST OF THIS AFTERNOON AND EVENING. WINDS SHOULD RELAX OVERNIGHT
AS HIGH PRESSURE BUILDS OVERHEAD. THE MOIST SOIL FROM RECENT
RAINFALL SHOULD ALLOW SOME BOUNDARY LAYER FOG TO FORM LATER
TONIGHT. GUIDANCE SHOWS THAT THE ROA/LYH/DAN SITES WILL REMAIN
VFR THROUGH THE NIGHT...BUT THERE COULD BE BRIEF MOMENTS OF MVFR
DURING THE EARLY MORNING. MEANWHILE...LWB AND BCB WILL EXPERIENCE
VISIBILITIES FALLING TO IFR AND LIKELY LIFR DUE TO LOCALLY DENSE
FOG. DEWPOINTS ARE CURRENTLY DROPPING TO THE LOWER 40S AT THESE
SITES...SO IT MAY BE POSSIBLE FOR THE FOG TO REMAIN JUST AT MVFR.
FOR BLF...MODEL GUIDANCE SUGGESTS THE POTENTIAL FOR MVFR FOG...BUT
ANY FURTHER DROP TO LIFR IS NOT CERTAIN. THE EARLY MORNING FOG
SHOULD LIFT BY 14Z AT ALL SITES.
WITH HIGH PRESSURE REMAINING IN CONTROL THROUGH FRIDAY...GOOD
FLYING WEATHER SHOULD PERSIST OUTSIDE OF POTENTIAL MORNING FOG FOR
THE USUAL LOCATIONS. A COLD FRONT WILL ARRIVE BY SATURDAY...WHICH
WILL BRING SCATTERED SHOWERS THROUGH SUNDAY. THUNDERSTORM CHANCES
FROM THIS FRONT APPEAR LOW DUE TO LACKING INSTABILITY. PERIODS OF
MVFR AND IFR CONDITIONS STILL SEEM POSSIBLE DURING THIS TIME. VFR
CONDITIONS SHOULD RETURN BY MONDAY...AS ANOTHER LARGE AREA OF HIGH
PRESSURE BUILDS OVER THE MID ATLANTIC.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...PW
NEAR TERM...NF/PW
SHORT TERM...DS
LONG TERM...PW
AVIATION...PW
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1201 PM EDT WED SEP 19 2012
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH FRIDAY. A COLD FRONT
WILL APPROACH THE MID ATLANTIC ON SATURDAY...WHICH WILL BRING THE
NEXT CHANCE OF RAIN.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1200 PM EDT WEDNESDAY...
HIGH TEMPERATURES WERE BUMPED UP A DEGREE OR TWO...AS SKIES HAVE
ALMOST CLEARED WEST OF THE BLUE RIDGE...AND CLOUD COVER OVER THE
PIEDMONT HAS BEGUN TO SCATTER DURING THE PAST COUPLE HOURS. WIND
SPEEDS WERE BUMPED SLIGHTLY UPWARD FOR THE NORTHERLY FLOW TAKING
SHAPE. ALTHOUGH THE RECENT NAM AND RAP MODELS SHOW A TINY AMOUNT
OF PRECIPITATION ALONG THE NORTHWEST NORTH CAROLINA MOUNTAINS DUE
TO UPSLOPE FLOW...THERE IS LITTLE IF ANY CHANCE OF SIGNIFICANT
MOISTURE DUE TO THE DRY AIR MASS SETTLING OVER THE MID ATLANTIC.
AS OF 1000 AM EDT WEDNESDAY...
CLOUD COVER STILL LINGERS OVER THE PIEDMONT FROM THE DEPARTING
COLD FRONT. HOWEVER...SKIES ARE QUICKLY CLEARING WEST OF THE BLUE
RIDGE. THE 12Z RNK SOUNDING REVEALS A CONSIDERABLE DROP IN
PRECIPITABLE WATER...FROM 1.31 INCHES LAST NIGHT TO ONLY 0.54
INCHES THIS MORNING. HIGH PRESSURE WILL CONTINUE TO BUILD OVERHEAD
THIS AFTERNOON. HIGH TEMPERATURES FOR TODAY STILL APPEAR ON
TARGET...AND NO OTHER SIGNIFICANT CHANGES WERE MADE.
AS OF 345 AM EDT WEDNESDAY...
THE COLD FRONT HAS EXITED EAST OF OUR AREA THIS MORNING...AND
INFRARED SATELLITE IMAGERY INDICATES THAT SKIES ARE CLEARING FOR
AREAS ALONG AND WEST OF THE BLUE RIDGE...WHILE LOW CLOUDS LINGER
ACROSS THE PIEDMONTS. AS DRIER AIR CONTINUES TO FILTER IN FROM THE
NORTHWEST THIS MORNING...EXPECT THE CLEARING TO CONTINUE...WITH
MOSTLY CLEAR SKIES EXPECTED ACROSS ALL BUT OUR FAR WESTERN
RIDGELINES DURING THE AFTERNOON...WHERE PARTLY CLOUDY SKIES WILL
PERSIST.
WITH BROAD UPPER LEVEL TROUGHING SITUATED ACROSS THE EASTERN
STATES FOR TODAY...TEMPERATURES WILL RANGE ANYWHERE FROM 7 TO 10
DEGREES BELOW NORMAL FOR THE SECOND HALF OF SEPTEMBER...BUT WILL
STILL REMAIN ON THE MILD SIDE. EXPECT HIGHS FOR TODAY TO RANGE
FROM THE LOW TO MID 60S ACROSS THE MOUNTAINS...TO THE LOW 70S
ACROSS THE PIEDMONTS. STUCK PRETTY CLOSE TO MAV GUIDANCE FOR
HIGHS...BUT WENT A DEGREE OR TWO BELOW MOST AREAS TO ACCOUNT FOR
MOIST SOIL CONDITIONS FROM TUESDAYS WIDESPREAD RAINFALL.
LOOKING INTO TONIGHT...HIGH PRESSURE WILL BEGIN TO SETTLE ALONG
THE APPALACHIAN SPINE...WHICH WILL MAKE FOR LIGHT WINDS ACROSS THE
AREA...AND MORE INDICATIONS THAT AUTUMN IS ALMOST OFFICIALLY UPON
US. EXPECT OVERNIGHT LOW TEMPERATURES TO RANGE FROM THE LOW TO MID
40S ACROSS THE MOUNTAINS...A FEW UPPER 30S ALONG THE HIGHER
RIDGELINES...TO THE LOW 50S ACROSS THE NORTH CAROLINA PIEDMONT.
WITH LIGHT WINDS EXPECTED...MOSTLY CLEAR SKIES AND MOIST SOILS...
EXPECT PATCHY FOG WILL DEVELOP MAINLY ACROSS THE MOUNTAINS AND
ESPECIALLY IN THE RIVER VALLEYS. MAY STILL HAVE ENOUGH
NORTHEASTERLY WIND FLOW IN THE PIEDMONTS TO KEEP A LID ON
WIDESPREAD FOG FORMATION...BUT STILL EXPECT TO SEE LOCALIZED DROPS
IN VISIBILITY FURTHER EAST BY SUNRISE THURSDAY MORNING.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
AS OF 245 AM EDT WEDNESDAY...
ON THURSDAY...THE AXIS OF SURFACE HIGH PRESSURE WILL EXTENT FROM THE
PARENT HIGH OVER NEW ENGLAND SOUTHWEST ALONG THE LEE OF THE
APPALACHIANS. CONCURRENTLY...AN UPPER LOW WILL BE JUST NORTH OF LAKE
SUPERIOR WITH ITS ASSOCIATED TROUGH AXIS EXTENDING SOUTH INTO THE
MID-MISSISSIPPI VALLEY. AS WE PROGRESS INTO THE START OF THE
UPCOMING WEEKEND...THE LOW/TROUGH IS EXPECTED TO AMPLIFY. THIS WILL
HAVE THE EFFECT OF TRENDING ANY ASSOCIATED COLD FRONTS SLOWER IN
THEIR APPROACH OF THE REGION. SOUTHWEST FLOW WILL BE ON THE INCREASE
ACROSS THE AREA AS THE CENTER OF THE SURFACE HIGH SHIFTS EAST AND
FLOW IN ADVANCE OF THE DEEPENING LOW INCREASES. ANTICIPATE DRY
WEATHER WITH A TREND FOR MODERATING TEMPERATURES THURSDAY AND
FRIDAY.
BY SATURDAY...TEMPERATURES WILL CONTINUE TO TREND MILDER.
HOWEVER...BY THE AFTERNOON...EXPECT INCREASING CLOUDS AND ISOLATED
TO SCATTERED SHOWERS ACROSS THE MOUNTAINS AS A COLD FRONT
APPROACHES. THE FRONT WILL CROSS THE REGION LATE IN THE AFTERNOON
INTO THE EVENING HOURS ON SATURDAY. THE BEST INSTABILITY LOOKS TO
REMAIN CLOSER TO THE COAST...SO WILL ONLY MENTION SHOWERS AT THIS
TIME.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 330 AM EDT WEDNESDAY...
BY SUNDAY...THE MODEL GUIDANCE DIVERGES SIGNIFICANTLY. THE GFS
BECOMES VERY PROGRESSIVE IN PUSHING THE UPPER LEVEL TROUGH
EASTWARD...WHICH WOULD CLEAR THE MID ATLANTIC AND PROVIDE DRIER
CONDITIONS. MEANWHILE...THE ECMWF HOLDS THE TROUGH BACK OVER THE
GREAT LAKES...AND BRINGS A SECOND SHORTWAVE TROUGH WITH A MORE
POTENT COLD FRONT THAT WOULD PROVIDE A BETTER CHANCE OF SHOWERS.
GIVEN THE PROGRESSIVE BIAS OF THE GFS...AND THE FACT THAT DEEP
UPPER LEVEL TROUGHS PROPAGATE AT A CONSIDERABLY SLOW RATE...ALL
THE FORECAST GRIDS WERE ADJUSTED TOWARD THE ECMWF SOLUTION. THE
UPPER LEVEL TROUGH WILL EVENTUALLY MOVE EASTWARD BY SUNDAY NIGHT.
A LARGE AREA OF HIGH PRESSURE WILL BUILD IN ON MONDAY AND PERSIST
THROUGH THE FIRST HALF OF NEXT WEEK. NORTHWEST WINDS BEHIND THE
DEPARTING COLD FRONT SHOULD PROVIDE DECENT COLD AIR ADVECTION. AS
DEWPOINTS FALL CONSIDERABLY...TEMPERATURES WILL ALSO DROP TO MAKE IT
FEEL LIKE AUTUMN...WITH HIGHS ONLY REACHING THE LOWER 60S TO LOWER
70S ON MONDAY. CALM WINDS AND MAINLY CLEAR SKIES DUE TO HIGH
PRESSURE OVERHEAD SHOULD ALLOW SUFFICIENT DECOUPLING IN THE LOWER
TROPOSPHERE DURING MONDAY NIGHT...WHICH WILL CAUSE LOWS TO PLUMMET
INTO THE UPPER 30S TO MID 40S BY TUESDAY MORNING.
&&
.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
AS OF 730 AM EDT WEDNESDAY...
CLOUD COVER CONTINUES TO BREAK UP THIS MORNING UNDER THE DOWNSLOPE
FLOW...WITH WINDS BECOMING INCREASING NORTHERLY AS HIGH PRESSURE
BUILDS INTO THE UPPER OHIO RIVER VALLEY. THE NORTHERLY WIND SHIFT
IS HELPING TO SCOUR OUT LOW LEVEL MOISTURE/CLOUDS THAT WERE DAMMED
AGAINST OUR WESTERN RIDGELINES OVERNIGHT...INCLUDING AT BLF...AND
EXPECT TO SEE THESE CLOUDS SCATTER BY LATE MORNING...MAKING FOR
VFR CONDITIONS THROUGH THE REMAINDER OF WEDNESDAY AREAWIDE.
WINDS WILL BECOME LIGHT TONIGHT AS HIGH PRESSURE CONTINUES TO
BUILD IN...SETTLING ALONG THE APPALACHIAN SPINE BY SUNRISE
THURSDAY MORNING. WITH COLD AIR ADVECTION DECREASING...MOIST SOIL
CONDITIONS FROM RECENT WIDESPREAD HEAVY RAINFALL...AND MINIMAL
CLOUD COVER EXPECTED...EXPECT TO SEE AREAS OF FOG DEVELOP ACROSS
THE MOUNTAINS...AND ESPECIALLY IN THE RIVER VALLEYS...AFTER
MIDNIGHT. VISIBILITIES WILL ALSO DROP FOR ROA...LYH AND DAN...BUT
WITH NORTHEASTERLY WINDS EXPECTED TO PERSIST...LIGHT COLD AIR
ADVECTION MAY LIMIT VISIBILITY DROPS TO THE 2SM TO 4SM RANGE.
HIGH PRESSURE WILL REMAIN ACROSS OUR AREA THROUGH THE REMAINDER OF
THE WORKWEEK...MAKING FOR VFR CONDITIONS OUTSIDE OF EARLY MORNING
FOG. ANOTHER COLD FRONT WILL APPROACH THE AREA ON SATURDAY
AFTERNOON AND EVENING...BRINGING A RETURN OF SHOWER ACTIVITY...
WITH A FEW THUNDERSTORMS POSSIBLE...AS WELL AS PERIODS OF MVFR AND
IFR CONDITIONS.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...PW
NEAR TERM...NF/PW
SHORT TERM...DS
LONG TERM...PW
AVIATION...NF