Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 102347
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
747 PM EDT THU JUL 10 2014

.SYNOPSIS...
A STATIONARY FRONTAL BOUNDARY WILL REMAIN OVER THE DELMARVA TONIGHT
BEFORE SLOWLY PUSHING SOUTH OF THE AREA FRIDAY. HIGH PRESSURE BUILDS
IN FROM THE NORTHEAST FRIDAY INTO SATURDAY. RETURN FLOW DEVELOPS
LATE IN THE WEEKEND AND EARLY NEXT WEEK AS HIGH PRESSURE MOVES
OFFSHORE AND AN STRONG UPPER LOW DIGS INTO THE UPPER MIDWEST. A COLD
FRONT WILL APPROACH THE EASTERN SEABOARD TUESDAY BEFORE MOVING
OFFSHORE BY WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
BACKDOOR COLD FRONT HAS CLEARED OUR CWA. BUT WITH TROFFING ALOFT,
THERE IS STILL SUFFICIENT INSTABILITY FOR SHOWERS AND
THUNDERSTORMS TO FORM. IF 7/8/14 WAS THE DAY THE HRRR AND COSPA
RAN TO THEIR AGENT AND RENEGOTIATE THEIR CONTRACTS, TODAY IS THE DAY
TO BE THANKFUL THE REVERSE CANT BE DONE. DIFFICULT MORE SUBTLE SCENARIO
WITH NONE OF THE MESOSCALE MODELS HANDLING/VERIFYING CONVECTION
WELL AND FALLING OFF TRACK RATHER QUICKLY WITHIN OUR CWA. WITH
SHORT WAVES STILL PROGGED TO PROGRESS THROUGH THE TROF, SFC BASED
INSTABILITY EXCEEDING 2K JOULES WEST, BOUNDARIES PROVIDING LIFT,
WE ARE GOING TO KEEP THE PRESENT FORECAST, WATCH, GOING UNTIL WE
SEE WHAT COMES OF THE CONVECTION EXITING THE ALLEGHENIES. ANY ESTF
UPDATES ARE GOING TO BE BASED ON ADJUSTING FOR TEMPS WHERE PCPN IS
OR JUST RECENTLY HAS OCCURRED.


A FLASH FLOOD WATCH HAS BEEN ISSUED FOR OUR DELMARVA AND SOUTHERN
NEW JERSEY COUNTIES WHERE IT HAS RAINED HEAVILY DURING THE DAY
TODAY, AND THE POTENTIAL FOR ADDITIONAL HEAVY RAIN EXISTS.
PW VALUES REMAIN HIGH WITH VALUES 1.75-2 INCHES ACROSS THE AREA.
MEANWHILE, THE MID-LEVEL TROUGH CONTINUES TO APPROACH THE AREA
FROM THE WEST AND SEVERAL VORTICITY IMPULSES WILL CONTINUE TO
SLIDE ACROSS THE AREA THROUGH THIS EVENING. ALL OF THIS COMBINED
WILL HELP ADDITIONAL SHOWERS AND THUNDERSTORMS DEVELOP. IT HAS
ALREADY RAINED ACROSS PORTIONS OF THE WATCH AREA TODAY, AND WHERE
IT HAS RAINED, IT`S BEEN VERY HEAVY WITH UP TO 3-4 INCHES IN SOME
AREAS IN AN HOUR OR TWO. WITH THE POTENTIAL FOR ADDITIONAL HEAVY
RAINFALL ACROSS THESE AREAS, WE HAVE ISSUED A FLASH FLOOD WATCH
THROUGH THIS EVENING.

THERE ARE SCATTERED SHOWERS AND THUNDERSTORMS MOVING THROUGH CENTRAL
AND NORTHEASTERN PENNSYLVANIA, THROUGH THESE HAVE BEEN MOVING AND
WILL LIKELY BE MORE DIURNAL IN NATURE AND SHOULD DISSIPATE AROUND
SUNSET; SO NO WATCH FURTHER NORTH.

WE EXPECT MUCH OF THE PRECIPITATION TO BEGIN TO DIMINISH LATER THIS
EVENING AND TOWARD MIDNIGHT AS INSATIABILITY WANES AND PW VALUES
BEGIN TO LOWER. THEREFORE THE WATCH ENDS AT LOCAL MIDNIGHT. HOWEVER,
WITH THE FRONT REMAINING NEARBY AND THE MID-LEVEL TROUGH STILL TO
OUR WEST, THERE WILL STILL BE THE POTENTIAL FOR A FEW SHOWERS AND
THUNDERSTORMS INTO FRIDAY MORNING.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
THE PESKY FRONTAL BOUNDARY IS EXPECTED TO PUSH BACK OFFSHORE ON
FRIDAY, AND STALL ACROSS THE OCEAN WATERS TO OUR EAST. PW VALUES
CONTINUE TO LOWER THROUGH THE DAY, BUT THE MID-LEVEL THROUGH WILL BE
MOVING OVERHEAD THROUGH THE DAY. THERE WILL REMAIN THE CHANCE FOR
ISOLATED-SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE AREA, WITH
THE BEST POTENTIAL ACROSS SOUTHERN NEW JERSEY AND SOUTHERN DELMARVA.

HIGHS ON FRIDAY WILL DEPEND ON HOW MUCH SUNSHINE WE GET, WITH CLOUDY
AREAS LIKELY BEING CLOSER TO THE COOLER MET GUIDANCE AND SUNNIER
AREAS CLOSER TO THE WARMER MAV GUIDANCE. FOR NOW, WE TOOK A BLEND OF
THE MAV/MET/MOSGUIDE FOR DAYTIME HIGHS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
SURFACE HIGH PRESSURE CENTERED JUST EAST OF NEW ENGLAND WILL PROVIDE
NICE WEATHER THROUGH SATURDAY. FRIDAY NIGHT WILL FEATURE CLEAR SKIES
AND COOL TEMPERATURES FOR THIS TIME OF YEAR, AND AN EASTERLY FLOW
WILL KEEP HIGHS IN THE 80S ON SATURDAY. CONDITIONS WILL BEGIN TO
DETERIORATE SOMEWHAT ON SUNDAY AS A FRONTAL BOUNDARY APPROACHES FROM
THE WEST. CLOUDS WILL BE ON THE INCREASE AND SHOWERS AND
THUNDERSTORM ACTIVITY WILL BECOME INCREASINGLY LIKELY FROM WEST TO
EAST AS THE DAY WEARS ON. THESE CLOUDS SHOULD KEEP THE HIGH
TEMPERATURES ON SUNDAY ONE OR TWO DEGREES COOLER THAN SATURDAY.

AN ANOMALOUSLY STRONG NRN STREAM CLOSED LOW IS FORECAST TO DIVE SOUTHWARD
FROM NEAR HUDSON BAY INTO THE UPPER MIDWEST EARLY NEXT WEEK, SETTING
UP A RATHER UNUSUAL PATTERN FOR THIS TIME OF YEAR. THE MID-ATLANTIC
REGION WILL BE SITUATED IN AN INCREASINGLY DIFFLUENT FLOW PATTERN
ALOFT ON THE SOUTHEASTERN PERIPHERY OF THE AMPLIFYING UPPER TROUGH
AND ON THE WESTERN PERIPHERY OF THE WESTERN ATLANTIC RIDGE. THE HEAT
AND HUMIDITY WILL RETURN MONDAY AND TUESDAY DURING THIS TIME AS
STRENGTHENING SOUTHWESTERLY FLOW AHEAD OF THE LOW BECOMES
ESTABLISHED OVER THE EASTERN CONUS. MAX TEMPS IN THE LOWER 90S
APPEAR LIKELY MONDAY AND TUESDAY. LEANED TOWARD THE SLOWER ECMWF
SOLUTION REGARDING THE ARRIVAL OF THE FROPA ON TUESDAY. RAISED MAX
TEMPS A FEW DEGREES FROM 12Z WPC GUIDANCE AS A SLOWER SOLUTION WOULD
KEEP THE PRE-FRONTAL WARM AIRMASS THAT IS CHARACTERIZED BY 850 MB
TEMPS NEAR 20C OVER THE AREA INTO TUESDAY. MAX TEMPS IN THE LOWER
90S OVER THE COASTAL MID-ATLANTIC REGION FOR ONE MORE DAY.

MONDAY AND TUESDAY BOTH LOOK TO BE A RATHER STORMY PERIOD FOR THE
AREA. THE FOCUS FOR CONVECTION APPEARS TO BE A PRE-FRONTAL/LEE
TROUGH ON MONDAY AND THE MAIN COLD FRONT FOR TUESDAY. FAVORABLE
DYNAMICS IN THE RIGHT ENTRANCE REGION OF AN UNSEASONABLY STRONG
UPPER-LEVEL JET STREAK AND AHEAD OF THE APPROACHING LONGWAVE TROUGH
ALSO LOOKS TO CONTRIBUTE TO SYNOPTIC LIFT OVER THE AREA ON TUESDAY.
THERE ARE STILL PLENTY OF DETAILS THAT NEED TO BE WORKED OUT THIS
FAR OUT, BUT THE POTENTIAL IS THERE FOR SEVERE THUNDERSTORM EVENTS
BOTH DAYS. SPC HAS DEPICTED THE AREA IN A DAY 6 SLIGHT RISK FOR
TUESDAY.

COLD FROPA LIKELY TUESDAY NIGHT OR EARLY WEDNESDAY. MUCH COOLER
AND DRIER CONDITIONS ARE FORECAST TO RETURN BEHIND THE COLD FRONT
BY WEDNESDAY. THE 12Z ECMWF INDICATES H8 TEMPS DROPPING INTO THE
SINGLE DIGITS BEHIND THE FRONT.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

00Z TAFS CARRY SOME MVFR CONDITIONS INLAND AT FOGGIER TERMINALS
AND IFR CIGS AT COASTAL TERMINALS LATER TONIGHT.

FOR THIS EVENING, CONVECTION IN THE SUSQUEHANNA VALLEY IS ONLY
SLOWLY DRIFTING EASTSOUTHEAST. SHOWERS INCLUDED AT KRDG INITIALLY,
ALTHOUGH KILG MIGHT NEED AN AMENDMENT IF THEY STAY TOGETHER
LONGER THAN ANTICIPATED. OTHERWISE NON COASTAL TERMINALS SHOULD
HAVE VFR CONDITIONS WITH MAINLY MID LEVEL CIGS OR HIGHER AND LIGHT
EAST WINDS. AT THE COAST, CONFIDENCE IS LESS THAN AVERAGE, BUT
WITH RAIN OFFSHORE AND ONSHORE WIND, WE ARE PREDICTING AN IFR CIG
TO FORM AT THE TERMINALS.

OVERNIGHT, PRIMARILY VFR CONDITIONS WITH SOME MVFR RESTRICTIONS
DUE TO FOG AT SMALLER AIRPORTS AND TERMINALS. ANY CIG SHOULD BE
VFR MID LEVEL OR HIGHER. WINDS WILL BE LIGHT. AT THE COASTAL
TERMINALS (KACY AND KMIV), WE WILL CONTINUE THE IFR CIG WITH SOME
MVFR VSBY RESTRICTIONS. CONFIDENCE LESS THAN AVERAGE.

ON FRIDAY VFR CONDITIONS EXPECTED OR WILL BE REACHED (AT THE COASTAL
TERMINALS) AT ALL AIRPORTS DURING THE MORNING. PCPN CHANCES
OVERALL ARE LESS THAN TODAY AND NO MENTION WILL BE MADE. SOME
CUMULUS CLOUDS SHOULD FORM, BUT NOT EXPECTING A VFR CIG. WINDS
WILL BE LIGHT FROM THE EAST AND A BAY AND SEA BREEZE FRONT SHOULD
FORM. NOT SURE IF A VERY SHARP DISCONTINUITY WILL FORM AS THE
GENERAL WIND FIELD SHOULD BE FROM THE EAST.


OUTLOOK...
FRIDAY NIGHT THRU SATURDAY NIGHT...POTENTIAL FOR IFR CIGS WITH
MARINE STRATUS TO IMPACT TERMINALS, PARTICULARLY ACY/MIV, FRIDAY AND
SATURDAY NIGHTS WITH ONSHORE FLOW. OTHERWISE VFR EXPECTED WITH DRY
CONDITIONS.

SUNDAY AND MONDAY...CHANCE FOR SHRA/TSRA BOTH DAYS. BETTER CHANCE
MAY BE MONDAY WITH A WELL-DEFINED SFC TROUGH DEVELOPING OVER THE
EASTERN SEABOARD. LOCAL/BRIEF RESTRICTIONS POSSIBLE.

TUESDAY...BETTER CHANCE FOR SHRA/TSRA TUESDAY AS A COLD FRONT
APPROACHES.

&&

.MARINE...
SUB-ADVISORY CONDITIONS ARE EXPECTED THROUGH TONIGHT AND FRIDAY WITH
A FRONTAL BOUNDARY DRAPED ACROSS THE WATERS. THERE REMAINS A CHANCE
FOR SHOWERS AND THUNDERSTORMS THROUGH FRIDAY; EXPECT HIGHER WINDS
AND WAVES NEAR THUNDERSTORMS.

OUTLOOK...
FRIDAY NIGHT THROUGH AND SATURDAY NIGHT...HIPRES BUILDS IN FROM THE
NORTHEAST STATES TO START THE WEEKEND. ONSHORE FLOW WILL BE LIGHT.

SUNDAY THROUGH TUESDAY...WINDS VEER, BECOMING SOUTHWESTERLY ON SUNDAY.
SOUTHWEST WINDS STRENGTHEN MONDAY BUT SHOULD REMAIN BELOW SCA
LEVELS. GUSTY SOUTHERLY WINDS AHEAD OF A COLD FRONT ON TUESDAY.
MARGINAL SCA POSSIBLE. CHANCE FOR SHRA/TSRA LATE SUNDAY. BETTER
CHANCE ON MONDAY AND TUESDAY.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR NJZ016-
     021>024.
DE...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR DEZ001>004.
MD...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR MDZ008-012-
     015-019-020.
MARINE...NONE.

&&

$$
SYNOPSIS...KLEIN
NEAR TERM...GIGI/ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...KLEIN/MIKETTA
AVIATION...GIGI/KLEIN
MARINE...KLEIN/ROBERTSON





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