Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 271517
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1117 AM EDT SUN JUL 27 2014

.SYNOPSIS...
A WARM FRONT WILL MOVE NORTHWARD THROUGH OUR AREA TODAY. A LOW
PRESSURE SYSTEM WILL MOVE EASTWARD FROM THE GREAT LAKES REGION AND
DRAG A COLD FRONT ACROSS THE AREA ON MONDAY. HIGH PRESSURE WILL
START TO MOVE INTO THE REGION ON TUESDAY, BUILDING ACROSS THE REGION
THROUGH THE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
NO BIG CHANGES ARE PLANNED WITH THIS UPDATE. KPBZ MORNING SOUNDING
SHOWING WHY THERE IS A LULL IN ACTIVITY AT THE PRESENT MOMENT AS
THERE WAS A POCKET OF COOL AIR ADVECTION OVER PA AT 925MB AND
850MB. GENERAL UA ANALYSIS SHOWING A PAIR OF 700MB TROFS, ONE JUST
EAST OF THE SUSQ VALLEY AND THE OTHER IN THE CENTRAL OH VALLEY.
THIS ALSO COINCIDES WITH MUCH DRIER AIR AT 500MB AND THE EXIT
REGION OF THE APPROACHING 300/250MB JET. THIS IS THE REAL DEAL AS
THERE IS WAA WEST OF PBZ AT 925/850MB AS WELL AS PRESENTLY THE
BEST VALUES OF EFFECTIVE BULK SHEAR AND ML CAPES ALREADY EXCEEDING
1000J.

LOCALLY THE WEST WINDS BEHIND THE DEPARTING SHORT WAVE HAVE
DROPPED DEW POINTS BACK DOWN INTO THE MID TO UPPER 60S MOST
PLACES. CONVECTIVE TEMPS THOUGH ARE IN THE LOWER 80S NORTH, BUT
NEAR 90 DELMARVA. THE DELMARVA PBLM IS COMPLICATED BY DEBRIS
CLOUDINESS OVERHEAD AND TO THE WEST.

THUS THE WAITING GAME CONTINUES WITH THE HARDEST AND MOST LIKELY
IMPACT FOR OUR CWA DURING TONIGHT. THE MESOSCALE MODELS ARE
POPPING SOME DISCRETE CELLS DURING THE AFTERNOON OVER THE HIGHER
TERRAIN. HAVE GREATER CONFIDENCE ABOUT THE POCONOS THAN THE BLUE
RIDGE ATTM BECAUSE OF CLOUDS OVER THE LATTER. BUT THE AFTERNOON IS
LONG ENOUGH THAT NEITHER CAN BE DISCOUNTED. GIVEN THE PREDICTED
INCREASE IN BULK SHEAR, THESE TOO ARE CAPABLE OF BEING
STRONG/SEVERE TSTMS AND WE WILL KEEP ENHANCED WORDING IN FOR THIS
AFTERNOON.

GIVEN HOW QUICKLY TEMPERATURES ARE RESPONDING, WE ARE GOING TO UP
MAX TEMPS TO INCLUDE SOME 90S. BUT DEW POINTS HAVE DROPPED AND
THIS KEEPS HEAT INDEX VALUES BELOW ANY HEAT ADVISORY THRESHOLDS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
FOR TONIGHT, THE AFOREMENTIONED CDFNT WILL CROSS THE REGION.  THE
HIGHEST POPS THRU THIS WHOLE EVENT COULD END UP BEING TONIGHT FIRST
WITH TSTMS THEN WITH SOME SHWRS.  THERE ARE STILL TIMING ISSUES WRT
TO THE FRONT, BUT IT STILL WILL NOT HAVE CLEARED THE REGION BY
DAYBREAK MON.  THE GFS IS FASTER THAN THE ECMWF, WHICH IS NOT
SURPRISING.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
AT THE SURFACE...A COLD FRONT WILL CROSS THE REGION ON MONDAY. HIGH
PRESSURE FROM THE WEST WILL GRADUALLY BUILD INTO THE REGION THROUGH
THE END OF THE WEEK.

IN THE MID LEVELS...A MID LEVEL TROUGH WILL DIG DOWN ACROSS THE
EASTERN UNITED STATES, WITH MULTIPLE SHORTWAVES ROTATING THROUGH IT
DURING THE WEEK. THE TROUGH STARTS TO RETROGRADE AND WILL DEEPEN AS
IT SETTLES TO OUR WEST.

BY MONDAY MORNING, A LOW PRESSURE SYSTEM WILL BE LOCATED ACROSS
EASTERN NEW YORK AND WILL BE MOVING INTO NEW ENGLAND. THIS LOW WILL
DRAG A COLD FRONT INTO OUR REGION DURING THE MORNING, CROSSING
THROUGH THE REGION DURING THE DAY. SHOWERS AND THUNDERSTORMS WILL
REMAIN POSSIBLE WITH FRONTAL PASSAGE AND WITH PRECIPITABLE WATER
VALUES INCHING UP TOWARDS 2 INCHES, THERE WILL BE A THREAT FOR SOME
HEAVY RAINFALL. SHOWERS WILL DECREASE THROUGH THE DAY AS THE FRONT
PUSHES OFFSHORE, WITH ONLY SOME LINGERING SHOWERS THROUGH THE
EVENING WITH PRECIPITATION ENDING BEFORE MIDNIGHT.

HIGH PRESSURE WILL START TO BUILD INTO THE REGION ON TUESDAY AND
EVENTUALLY WILL OVERSPREAD THE AREA BY THE END OF THE WEEK. WHILE IT
APPEARS WE SHOULD REMAIN MOSTLY DRY THIS WEEK WITH THE HIGH
BUILDING INTO OUR AREA, SHORTWAVES EMBEDDED IN THE MID LEVEL FLOW
WILL BE ROTATING THROUGH THE BASE OF THE TROUGH AND MAY HELP TO
SPARK OFF SOME SHOWERS. HOWEVER, THIS WILL BE DEPENDENT ON WHERE THE
SHORTWAVES MOVES THROUGH THE REGION FROM DAY TO DAY.

AS THE TROUGH RETROGRADES, IT DEEPENS AND AS A RESULT, WE SHOULD
START TO HAVE AN INCREASE IN MOISTURE ACROSS OUR AREA. SHORTWAVES
WILL CONTINUE TO ROTATE THROUGH THE MID LEVEL FLOW AND AGAIN MAY AID
IN THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS, MAINLY TOWARD THE
END OF THE WEEK AND HEADING INTO THE WEEKEND.

WITH THE DEEPENING MID LEVEL TROUGH NEAR OUR AREA, OUR TEMPERATURES
WILL COOL OFF A BIT AND BE BELOW NORMAL BEHIND THE COLD FRONTAL
PASSAGE. AS THE TROUGH STARTS TO PUSH TO THE WEST, WE SHOULD START
TO SEE A MODERATION IN THE TEMPERATURES OCCUR FOR MID TO LATE WEEK.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

A LOW CONFIDENCE AND COMPLICATED FCST DAY, BUT SHWRS AND TSTMS ARE
EXPECTED TO IMPACT THE TERMINAL SITES LATER TODAY.  LATEST RADAR
ALREADY HAS SOME SCT SHWRS AROUND AS REMNANTS OF A SYS FROM THE
MIDWEST WEAKEN AND GENLY MOVE BY TO OUR SW.  THEN, A COMPLEX LOW
PRES SYS IN SERN CANADA AND ITS ASSOCD CDFNT WILL APPROACH AND MOVE
THRU TONIGHT INTO MON.  THIS FRONT WILL TRIGGER SHWRS AND TSRA.  ANY
OF THE OR TSRA THIS MRNG OR LATER COULD BRING REDUCED CIGS/VSBYS.

THE GUID SEEMS TO HAVE PUSHED BACK THE ONSET TIME WITH THE ACTIVITY
LATER THIS AFTN/EVE, SO HAVE TAKEN THAT APPROACH IN THE TAFS, SO
HAVE TRENDED IN THAT DIRECTION AND STILL COULD BE TOO FAST...OR NOT.

ONCE THE CONVECTION MOVES THROUGH, THERE WILL LIKELY BE SOME
LINGERING SHOWERS INTO THE NIGHT UNTIL SOME IMPROVEMENT CLOSER TO
DAYBREAK OR BEYOND.

A GENL S WIND IS EXPECTED ERLY.  IT WILL BECOME MORE SWLY AND
INCREASE TO THE 10 TO 15 KT RANGE DURG THE DAY. IT WILL DECREASE
AND BECOME LIGHT (OUTSIDE OF ANY TSRA) OVERNIGHT AND GRADUALLY
BECOME MORE WLY BY DAYBREAK AS THE FRONT MOVES THRU.

OUTLOOK...
MONDAY...A COLD FRONT WILL CROSS THE REGION WITH MVFR/IFR CONDITIONS
POSSIBLE WITHIN SHOWERS AND THUNDERSTORMS. WEST TO SOUTHWEST WINDS
10 TO 15 KT WITH GUSTS 20 TO 25 KT.

MONDAY NIGHT...VFR CONDITIONS ARE EXPECTED TO RETURN DURING MONDAY
NIGHT AS THE FRONT PUSHES OFFSHORE. SHOWERS EARLY...THEN CLEARING.
WINDS WILL DIMINISH THROUGH THE EVENING, AROUND 5 KT OR LESS THROUGH
THE OVERNIGHT.

TUESDAY THROUGH THURSDAY...MAINLY VFR CONDITIONS ARE EXPECTED.

&&

.MARINE...
SLY TO SWLY FLOW WILL PREVAIL OVER THE AREA WATERS AND SEAS WILL
CONTINUE TO SLOWLY RISE.  BY DAYBREAK MON, WE COULD BE VERY CLOSE TO
SCA CONDS, ESPECIALLY OVER THE SRN WATERS, BUT CONFIDENCE IS NOT
HIGH ENOUGH TO ISSUE ANY HEADLINES ATTM.

OUTLOOK...
MONDAY...SEAS WILL BUILD IN ADVANCE OF A COLD FRONT AND LOOK TO
BUILD NEAR 5 FEET WITH WINDS GUSTING BETWEEN 20-25 KT. A SMALL CRAFT
ADVISORY MAY BE NEEDED FOR MONDAY.

MONDAY NIGHT...IMPROVING CONDITIONS AS BOTH SEAS AND WINDS ARE
EXPECTED TO DROP AS THE COLD FRONT MOVES OFFSHORE.

TUESDAY THROUGH THURSDAY...SUB-ADVISORY CONDITIONS ARE EXPECTED.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...MEOLA
NEAR TERM...GIGI
SHORT TERM...NIERENBERG
LONG TERM...MEOLA
AVIATION...NIERENBERG/MEOLA
MARINE...NIERENBERG/MEOLA






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