000
FXUS61 KCTP 171648
AFDCTP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1248 PM EDT THU MAY 17 2012
.SYNOPSIS...
HIGH PRESSURE BUILDING IN FROM THE GREAT LAKES WILL BRING DRY
WEATHER AND WARMING TEMPERATURES FOR THE WEEKEND. GREAT
UNCERTAINTY EXISTS CONCERNING THE POSSIBLE DEVELOPMENT OF AN
UPPER LOW WHICH MAY FORM OVER THE EAST COAST LATE THIS WEEKEND.
AT THIS POINT...THE NEXT CHANCE OF RAIN LOOKS TO BE MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
TEMPS WARMING QUICKLY UNDER FULL SUNSHINE IN MOST LOCATIONS AT
13Z. THE EXCEPTION WAS THE DEEPER VALLEYS IN NORTHWESTERN
PENNSYLVANIA /CONTAINING RIVERS AND LARGE STREAMS/ WHERE LOCALLY
DENSE FOG FORMED AS A RESULT OF AN AIR/WATER TEMP SPREAD OF 20 DEG
F OR MORE...WITH LOW TEMPS IN THE 30S AND STREAM TEMPS IN THE MID
TO UPPER 50S.
HIGH PRESSURE OVER THE GREAT LAKES WILL BUILD GRADUALLY EAST INTO
THE REGION TODAY. THIS WEATHER FEATURE...COMBINED WITH DRY LLVL
NORTHERLY FLOW AND DECREASING LAPSE RATES ALOFT WILL KEEP SKIES
ESSENTIALLY CLOUD-FREE.
MAX TEMPS THIS AFTERNOON IN THE UPPER 60S TO LOWER 70S WILL BE
SEASONAL FOR MOST OF THE AREA...AND JUST SLIGHTLY BELOW NORMAL IN
THE NORTH WITH HIGHS IN THE LOWER 60S.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
THE BIGGEST FORECAST PROBLEM FOR TONIGHT IS AGAIN THE POSSIBILITY
OF FROST IN THE NRN MTS. GOOD RADIATIONAL COOLING UNDER LOW PWAT
COLUMN WILL HELP TEMPS DROP INTO THE M30S AGAIN IN THE
NORTH...AND WINDS SHOULD BE LIGHT/NIL. DEWPOINTS WILL BE IN THE
U20S N TO THE M30S S. WHILE PATCHES OF FROST ARE POSSIBLE DOWN TO
I-80...WILL JUST TAKE A DEG OR TWO OFF THE MOS PROGS FOR TONIGHT.
WILL CONTINUE TO MENTION FROST IN THE HWO AND WX GRIDS...BUT HOLD
OFF ISSUING AN ADVY AT THIS TIME. SINCE THERE IS A CURRENT FROST
ADVY OUT...PEOPLE SHOULD ALREADY BE ATTUNED...AND FEEL WAITING
UNTIL THE CURRENT ADVY IS DEAD TO POST ONE FOR THE NEXT NIGHT WILL
DO NO HARM.
FRIDAY LOOKS LIKE A STELLAR DAY. PERIOD. IT WILL FEEL VERY WARM IN
THE FULL SUN...BUT THE DRY AIR WILL MAKE IT MORE-COMFORTABLE.
IT WILL BE A DRY HEAT - AS THEY SAY IN ARIZONA. MAXES WILL TRY TO
GET TO 80F IN VALLEY LOCATIONS OF THE EAST...WITH WIDESPREAD M70S
ELSEWHERE. ONLY THE HILL TOPS WILL HAVE THE THERMOMETER STOP
AROUND 70F DUE TO A SLIGHTLY SHALLOW-ER MIXING DEPTH.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE WILL CONTINUE FAIR AND DRY WEATHER INTO THE
UPCOMING WEEKEND. HEIGHTS WILL RISE ALOFT INTO THE UPPER OH VLY
BUT IT APPEARS AND UPPER LOW WILL UNDERCUT THE RIDGE AND FORM A
WEAK REX-BLOCK CONFIGURATION OVER THE NORTHEAST/MID-ATLC STATES
THIS WEEKEND.
...UPDATE CONCERNING ELONGATED/STATIONARY CIRCULATION
UNDERCUTTING THE UPPER RIDGE OVER THE MID-ATLC REGION THIS WEEKEND...
THE 17/00Z MODEL AND ENSEMBLE SPREAD NARROWED TO SOME EXTENT BUT
THERE WERE STILL SIGNIFICANT DIFFS...SOME OF WHICH LEAD TO
DRASTICALLY DIFFERENT SENSIBLE WEATHER CONDITIONS THAN CURRENTLY
FORECAST. AN INTERMEDIATE SOLUTION COMPRISED OF A 50/50 SPLIT OF
THE 00Z NAM AND CANADIAN WAS THE OVERNIGHT MODEL PREFERENCE AND
HAD BROAD SUPPORT FROM OTHER GLOBAL MODEL AND ENSEMBLE DATA.
THE 17/12Z NAM REMAINS QUITE BULLISH ON CONSOLIDATING THE
ELONGATED N-S SHEAR ZONE/DEEP MSTR AXIS ALONG WRN ATLC GULF
STREAM INTO A DIFFUSE VORTEX...AND WRAPS PCPN NWWD INTO THE MID-
ATLC STATES SAT-SUN AS THE UPPER WEAKNESS MIGRATES WWD/INLAND. THE
12Z CANADIAN AND UKMET CLUSTER REASONABLY WELL WITH THE
NAM...WHILE THE 12Z GFS AND 00Z ECMWF /TO A LESSER EXTENT/ KEEP
THE MOISTURE AXIS/PCPN MOSTLY OFFSHORE.
GIVEN THE SPREAD IN THE MODEL DATA...CONFIDENCE REMAINS BELOW AVG
FROM LATE IN THE WEEKEND INTO EARLY NEXT WEEK. THE AFTN FINALS
WILL LKLY BE COMPRISED OF A MULTI-MODEL AND HPC BLEND IN THE HOPE
OF MITIGATING SOME OF THE UNCERTAINTY RELATED TO THE SYSTEM
LURKING OFF THE EAST COAST.
AT LONGER RANGES IT STILL LOOKS LIKE A FRONTAL BOUNDARY WILL TRY
TO PUSH EWD FM THE GRT LKS BUT WILL LKLY BE IMPEDED BY THE SYSTEM
NEAR THE COAST. HIGH PRES WOULD FOLLOW IN THE WAKE OF THIS SYSTEM
FOR THE MIDDLE OF NEXT WEEK.
&&
.AVIATION /16Z THURSDAY THROUGH MONDAY/...
HIGH PRESSURE AND ASSOCIATED DRY AIR MASS WILL BUILD SOUTHEAST
FROM THE GRT LKS TODAY AND TONIGHT...RESULTING IN A HIGH
CONFIDENCE FORECAST OF CLEAR SKIES AND LIGHT WINDS.
OUTLOOK...
FRI-SUN...NO SIG WX EXPECTED.
MON...ISOLD PM THUNDERSTORM IMPACTS POSSIBLE.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO/LAMBERT
NEAR TERM...DANGELO/LAMBERT
SHORT TERM...DANGELO
LONG TERM...STEINBUGL
AVIATION...FITZGERALD
NWS CTP Office Area Forecast Discussion
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