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313
FXUS61 KPHI 170029
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
829 PM EDT WED APR 16 2014

.SYNOPSIS...
HIGH PRESSURE WILL CREST ACROSS THE AREA TONIGHT BEFORE MOVING INTO
NEW ENGLAND THURSDAY. A RIDGE EXTENDING ACROSS THE MIDDLE ATLANTIC
REGION WILL CONTINUE TO INFLUENCE OUR WEATHER INTO FRIDAY. A COLD
FRONT AND UPPER TROUGH WILL CROSS OUR AREA FRIDAY NIGHT AND EARLY
SATURDAY. MORE HIGH PRESSURE WILL ARRIVE LATER SATURDAY AND REMAIN
OVER THE AREA INTO MONDAY. A DISTURBANCE WILL MOVE TOWARDS THE AREA
NEXT TUESDAY.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
MAINLY CLEAR CONDITIONS CONTINUE ACROSS THE REGION THIS EVENING,
WITH JUST A LITTLE CIRRUS STREAMING IN FROM THE WEST. WINDS HAVE
DIMINISHED ACROSS THE CWA BUT SHOULD REMAIN IN THE 5 TO 10 MPH
RANGE MOST OF THE NIGHT, VEERING FROM THE NORTH TO THE NORTHEAST.
THE CLEAR SKIES AND LIGHTER WINDS, AS WELL AS A DRY AIRMASS IN
PLACE, WILL ALLOW FOR GOOD RADIATING CONDITIONS, ESPECIALLY
THROUGH THE OVERNIGHT. MINIMUM TEMPS STILL LOOK ON TRACK WITH THE
LATEST GUIDANCE, BUT WE DID ADJUST HOURLY TEMPS AND DEWPOINTS
USING THE LAV/LAMP GUIDANCE TO CAPTURE CURRENT TRENDS AND
OBSERVATIONS.

OTHERWISE, THE SFC HIGH PRES WILL CONT TO MOVE EWD THROUGH NY AND
INTO NEW ENGLAND BEFORE MORNING. A SFC RIDGE EXTDS SWWD FROM THE
CENTER ACROSS THE MID-ATL REGION BUT OUR FCST AREA REMAINS IN A
PRES GRAD PATTERN WHICH SHOULD MAINTAIN NE TO E WINDS OVERNIGHT.
IN SPITE OF THE WINDS HWVR...WITH CLEAR SKIES AND AN UNSEASONABLY
COLD AIR MASS IN PLACE WE EXPECT TEMPS TO FALL BELOW FREEZING IN
MOST AREAS FOR SEVERAL HOURS BETWEEN MIDNIGHT AND SUNRISE THURSDAY
MORNING. HENCE WE MAINTAIN A FREEZE WARNING FOR AREAS IN SE
PA...CNTRL/SRN NJ...AND NRN DELMARVA WHERE THE GROWING SEASON HAS
BEGUN. THE MET/MAV/ECS GUIDANCE ARE IN GOOD AGREEMENT ON THE
FREEZING TEMPS.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
FOR THURSDAY...THE SFC HIGH PRES RIDGE PRETTY MUCH REMAINS IN PLACE
OVER THE EASTERN SEABOARD...WHICH IN COMBO WITH THE OFFSHORE FRONTAL
TROF WILL MAINTAIN AN E/NE ONSHORE FLOW. FCST RH FOR THE LOWER TROP
IS RATHER LOW...BUT THE PERSISTENT ONSHORE LOW-LVL FLOW MAY
EVENTUALLY BRING IN SOME MOISTURE AND CLOUDINESS. THE AIR MASS TMRW
SHOULD NOT BE AS COLD AS TODAY AND CAA IS REPLACED BY WAA. HENCE MAX
TEMPS ON THURS SHOULD BE A FEW DEGREES WARMER THAN TODAY BUT STILL
QUITE A BIT BELOW NORMAL FOR MID APRIL.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
HIGH PRESSURE TO THE NORTHEAST WILL CONTINUE TO INFLUENCE OUR
WEATHER THURSDAY NIGHT AND FRIDAY. CLOUDS WILL BE ON THE INCREASE
FRIDAY...AS OUR REGION BEGINS TO FEEL THE EFFECTS OF THE ERLY FLOW
AROUND THE PERIPHERY OF THE RIDGE. WE WILL CONTINUE WITH A DRY
FCST FOR THU NIGHT...AND ONLY MENTION SOME SLGT CHC FOR DRIZZLE OR
LIGHT RAIN ALONG THE MARINE ZONES FOR FRIDAY. LATER FCSTS MAY
INCLUDE SOME PCPN NEAR THE SHORE FOR FRI...BUT RIGHT NOW THAT
LOOKS NOT TOO LIKELY. TEMPS WILL BE SLIGHTLY BELOW NORMAL WITH THE
ONSHORE FLOW THU NIGHT AND FRI.

A UPPER TROUGH AND SFC COLD FRONT WILL CROSS THE AREA FRI NIGHT
AND EARLY SAT. THE FCST MODELS ARE NOT SHOWING MUCH PCPN WITH THE
SYSTEM. BOTH BRING MORE ENHANCED PCPN BOTH NORTH AND SOUTH OF THE
REGION. WE HAVE THEREFORE JUST KEPT SLGT CHC POPS FOR THE REGION
FOR FRI NIGHT. EXTRA CLOUDINESS MAY LINGER INTO SAT MORNING.

SAT THRU MON WILL HAVE DRY WEATHER OVER THE AREA AS HIGH PRESSURE
FROM CANADA EXTENDS ACROSS THE AREA. TEMPERATURES SAT WILL BE A
BIT BELOW NORMAL...BUT BY MON READINGS WILL JUMP BACK TO SEVERAL
DEGREES ABOVE NORMAL...WITH HIGHS IN THE UPPER 60S TO LOW 70S
REGION-WIDE. A SLGT CHC FOR A SHOWER WAS KEPT IN THE GRIDS FOR THE
EXTREME WRN/NRN MOST COUNTIES OF THE CWA...CONFID IN THIS IS LOW.

ANOTHER LOW AND COLD FRONT WILL APPROACH FOR MON NIGHT AND PERSIST
INTO TUE/TUE NIGHT. THE GFS AND EC BOTH SHOW SOME LIGHT QPF WITH
THE SYSTEM...SO THE CHC POPS OFFERED BY THE WPC WERE ACCEPTED FOR
THOSE PERIODS. TEMPS EARLY NEXT WEEK WILL REMAIN ABOVE NORMAL.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
CLEAR SKIES AND VFR CONDS ARE EXPECTED FOR THE REST OF THIS
EVENING AND TONIGHT. SOME LOW CLOUDS WITH BASES AROUND 3000 FT MAY
DEVELOP ON THURS WITH ONSHORE LOW-LVL WINDS...MORE LIKELY FROM PHL
SOUTH AND INTO THE AFTN...BUT OVERALL VFR CONDS SHOULD PREVAIL.
THE CONTINUED ONSHORE FLOW INTO THURSDAY NIGHT COULD LEAD TO SUB-
VFR CIGS, BUT CONFIDENCE ON THIS OCCURRENCE IS BELOW AVERAGE AND
WE ONLY HINTED AT THIS IDEA IN THE TAFS.

OTHERWISE, WINDS WILL CONTINUE TO VEER FROM A NORTHERLY DIRECTION
TO A MORE NORTHEAST DIRECTION THIS EVENING AND OVERNIGHT, BECOMING
MORE EASTERLY DURING THURSDAY. SPEEDS WILL AVERAGE 5 TO 10 KT
OVERNIGHT AND MORE IN THE 10 TO 15 KT RANGE DURING THURSDAY...SOMEWHAT
STRONGER TOWARD THE COAST AND WEAKER INTO ERN PA. SOME GUSTINESS
TO AROUND 20 KT MAY OCCUR FROM ABOUT MID-MORNING ONWARD, ESPECIALLY
AT KACY, BUT THIS WAS NOT INCLUDED IN THE TAFS AT THIS TIME.

OUTLOOK...
THU NIGHT AND FRIDAY...MOSTLY VFR. INCREASING CLOUDS FRIDAY.

FRIDAY NIGHT...VFR N/W. MVFR OR LOWER POSSIBLE NEAR THE SHORE WITH
AN ONSHORE FLOW. MVFR POSSIBLE OVER THE DEL VALLEY SITES.

SAT THRU MON...MOSTLY VFR.

&&

.MARINE...
AS BEST WE CAN TELL...WINDS OVER DEL BAY AND NJ/DE COASTAL WATERS
APPEAR TO HAVE DIMINISHED BELOW SCA THRESHOLD. HOWEVER...SEAS REMAIN
AROUND 5 FEET SO A SCA CONTINUES FOR ALL COASTAL WATERS. ALSO...THE
SFC PRES GRADIENT IS FCST TO INCREASE OVERNIGHT RESULTING IN
INCREASING NE WINDS AND GRADUALLY BUILDING SEAS. SCA CONDS ARE
LIKELY TO CONTINUE THROUGH THURSDAY AND BEYOND.

OUTLOOK...
THU NIGHT THRU FRIDAY...SCA CONDITIONS FOR SEAS...DIMINISHING.
FRI NIGHT THRU SUNDAY...SUB-SCA CONDITIONS EXPECTED.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...FREEZE WARNING FROM 1 AM TO 9 AM EDT THURSDAY FOR PAZ060-070-
     101>104-106.
NJ...FREEZE WARNING FROM 1 AM TO 9 AM EDT THURSDAY FOR NJZ012-013-
     015>023-027.
DE...FREEZE WARNING FROM 1 AM TO 9 AM EDT THURSDAY FOR DEZ001>003.
MD...FREEZE WARNING FROM 1 AM TO 9 AM EDT THURSDAY FOR MDZ008-012-
     015-019-020.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT FRIDAY FOR ANZ450>455.

&&

$$
SYNOPSIS...O`HARA
NEAR TERM...AMC/KLINE
SHORT TERM...AMC
LONG TERM...O`HARA
AVIATION...AMC/KLINE/O`HARA
MARINE...AMC/O`HARA







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