000
FXUS61 KPHI 111616
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1216 PM EDT TUE MAR 11 2014

.SYNOPSIS...
LOW PRESSURE IN EASTERN KANSAS WILL INTENSIFY RAPIDLY AFTER IT
ARRIVES IN KENTUCKY WEDNESDAY MORNING...THEN CROSSES NORTHERN NEW
JERSEY WEDNESDAY EVENING AND OUT TO THE GULF OF MAINE BY THURSDAY
MORNING. LOW PRESSURE IN EASTERN CANADA FRIDAY AND SATURDAY WILL
SEND ANOTHER COLD FRONT THROUGH THE MID ATLANTIC STATES EARLY
SUNDAY. LOW PRESSURE THEN DEVELOPS ALONG THE SOUTHEAST COAST OF
THE UNITED STATES NEXT MONDAY AND TUESDAY...COMPETING WITH GREAT
LAKES HIGH PRESSURE FOR DOMINANT INFLUENCE HERE IN THE MID
ATLANTIC STATES.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A WEAK SHORT WAVE/VORT MAX IS SWINGING INTO THE SOUTHERN PORTION
OF THE AREA THIS MORNING INTO THE EARLY AFTERNOON, WHILE THE COLD
FRONT IS SAGGING INTO THE AREA FROM THE NORTH. THIS IS LEADING TO
THE ENHANCEMENT OF CLOUD COVER ACROSS THE AREA, AS WELL AS SOME
REFLECTIVITY ON THE RADAR ACROSS THE DELMARVA. WE THINK MOST OF
THIS IS VIRGA, SO IT WOULD BE HARD FOR IT TO REACH THE GROUND
SINCE IT`S FALLING OUT OF THE MID-LEVELS, AND EVEN IF IT DOES, IT
SHOULD ONLY BE SPRINKLES. SO FOR NOW WE HAVE KEPT ANY MENTION OF
SHOWERS/SPRINKLES OUT OF THE FORECAST FOR NOW.

STAT GUIDANCE HAS BEEN UNDER DOING THE FORECAST HIGHS AND THE
NUMERICAL GUIDANCE HAS BEEN TOO COLD UPSTREAM AT 925 AND 850 MB.
ONCE AGAIN WENT ABOVE STAT GUIDANCE TODAY BY A COUPLE OF DEGREES
IN MOST SPOTS SO WE SHOULD CLIMB INTO THE LOW-60S AROUND THE
PHILLY METRO AREA AND FURTHER SOUTH AND EAST ONCE THE CLOUD COVER
BREAKS APART THIS AFTERNOON.

WITH THE WARMER TEMPERATURES AND MORE LOW-LEVEL MOISTURE ADVECTING
INTO THE REGION FROM THE SOUTHWEST, WE SHOULD REACH CONVECTIVE
TEMPERATURES ALLOWING A STRATOCU DECK TO FORM. ACROSS THE COASTAL
PLAIN IT LOOKS AS THOUGH A SEA BREEZE FRONT WILL BE ABLE TO MOVE
INLAND WITH THE LACK OF STRONGER LOW-LEVEL WINDS COMBATING IT.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
WE WILL BE UNDER THE INFLUENCE OF DEEP LAYER WARM AIR ADVECTION
TONIGHT SO WE EXPECT TO SEE THICKENING CLOUDS LOWERING WITH TIME
LATE TONIGHT. TEMPERATURES WILL NOT BE ABLE TO DROP OFF MUCH AFTER
SUNSET WITH AMPLE MID AND UPPER LEVEL CLOUD COVER AROUND AND
ADVECTING IN. THE WINDS DO BECOME LIGHT AND VARIABLE SO SOME
DECOUPLING IS EXPECTED BUT WITH A WARMER STARTING POINT WE SHOULD
BE SEVERAL DEGREES WARMER THAN THIS MORNING...MET/MAVMOS BLEND WAS
USED.

THE CURRENT 00Z GUIDANCE HAS TRENDED A LITTLE FURTHER NORTH
WITH THE TRACK OF THE SURFACE LOW KEEPING OUR ENTIRE CWA WITHIN THE
WARM SECTOR AND THEREFORE AN ALL LIQUID PRECIPITATION TONIGHT. THE
GFS HAS BEEN RUNNING FASTER THAN THE EC AND THE RGEM AND BRINGS THE
FIRST SHOT OF OVERRUNNING RAIN SHORTLY AFTER MIDNIGHT. THE 3 MODELS
ARE IN RELATIVELY GOOD AGREEMENT WITH THE STRENGTH AND EVOLUTION OF
THE SYSTEM AS IT ENTERS THE OHIO VALLEY LATE TONIGHT SO BASICALLY
USED A BLEND OF THE 3 TO GET A BETTER TIMING CONSENSUS FOR
INCREASING POPS. CHANCE TO LIKELY POPS ACROSS THE NORTH BY BEFORE
DAYBREAK WEDNESDAY MORNING.

WEDNESDAY...GFS, ECMWF, AND UKMET ARE IN RELATIVELY GOOD AGREEMENT
WITH THE TRACK OF THE LOW. THE NAM, ON THE OTHER HAND, IS THE
OUTLIER IN DIGGING AND INTENSIFYING THE LOW. FOR NOW, IT LOOKS
THAT A MAJORITY OF THE ASSOCIATED PRECIPITATION WILL OCCUR DURING
THE DAY WEDNESDAY AS THE REGION REMAINS IN THE WARM SECTOR. THE
COLD FRONT SHOULD SWEEP THROUGH THE REGION LATE WEDNESDAY
AFTERNOON INTO WEDNESDAY EVENING. ONE AREA OF NOTABLE DISAGREEMENT
AMONG THE MODELS IS THE POTENTIAL FOR WRAP AROUND, POST FRONTAL
PRECIPITATION WEDNESDAY EVENING, WHICH THE ECMWF SHOWS, BUT THE
GFS AND UKMET SHOW ONLY A VERY BRIEF WINDOW OF OPPORTUNITY. THIS
WOULD MAKE A BIG DIFFERENCE ON IMPACTS AS THE ONLY WINDOW OF
WINTRY PRECIPITATION WOULD BE BEHIND THE FRONT. FOR NOW, GIVEN THE
SOURCE REGION OF THE AIRMASS, AND THE MODEL DEW-POINT TEMPERATURES
POST FRONTAL, THINK THAT ANY POST FRONTAL WINTRY PRECIPITATION
WILL BE BRIEF. THE OTHER CONCERN IS THUNDERSTORMS AHEAD OF AND
WITH THE FRONT. THOUGH INSTABILITY IS VERY LIMITED, MU CAPE VALUES
LESS THAN 500 J/KG, GIVEN THE IMPRESSIVE LOW AND MID LEVEL FLOW,
GUSTY WINDS WILL BE POSSIBLE ESPECIALLY IF A LINE OF STORMS
DEVELOPS ALONG THE FRONT, AND IS ABLE TO TRANSLATE THE LOW LEVEL
JET DOWN TO THE SURFACE.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
WE ARE POSTING THE SYNOPSIS...LONG TERM SECTIONS EARLIER THAN
USUAL SINCE THE 12Z/11 GFS HAS CONFIRMED THE 12Z/11 NAM. WE`LL
UPDATE THE WEEKEND/EARLY NEXT WEEK SECTIONS FURTHER IN THE 330 PM
AFD UPDATE.

500 MB: A SHARP COLD TROUGH CROSSES THE REGION WEDNESDAY NIGHT WITH
RIDGING TO FOLLOW LATE THURSDAY AND FRIDAY. THEREAFTER... A LARGE
SCALE CYCLONIC FLOW APPEARS TO DOMINATE THE PATTERN ACROSS THE
NORTHEASTERN UNITED STATES WITH SPOKES OF SHORT WAVE ENERGY
TRANSITING THROUGH THE OVERALL WESTERLY FLOW IN OUR AREA.

TEMPERATURES: CALENDAR DAY AVERAGE WELL BELOW NORMAL THURSDAY AND FRIDAY
WITH DAYTIME MAX TEMPS AT LEAST 20 DEGREES BELOW NORMAL THURSDAY.
TEMPS WARMING TO NEAR NORMAL THIS WEEKEND BUT COOLING TO MAYBE 10
DEGREES BELOW NORMAL EARLY NEXT WEEK. STILL SOME UNCERTAINTY
REGARDING HOW MUCH COOLING EARLY NEXT WEEK.

FORECAST BASIS...12Z/11 50-50 BLENDED GFS/NAM MOS GUIDANCE WED NIGHT-
THU NIGHT, GFS MEX MOS GUIDANCE FRIDAY AND FRIDAY NIGHT THEN
1522Z/11 WPC GUIDANCE SAT-TUE. THE 09Z/11 SREF 3 HR POPS AND
12Z/11 GEFS 6 HR POPS FOR .05 WILL BE REVIEWED WITH ANY
SIGNIFICANT ADJUSTMENTS TO THE ABOVE IN THE FORECAST NOTED.

AS OF 1230PM...THE FORECAST BEYOND THURSDAY MORNING HAS NOT YET
BEEN UPDATED.

THE DAILIES BELOW...

WED NIGHT...WIND ADVISORY POTENTIAL WITH ABOUT 10 MB 3 HR PRESSURE
RISES COMBINING WITH STRONG CAA AND A DEEPENING 980MB SFC LOW MOVING
ENE FROM BOSTON SHOULD PERMIT ISOLATED POWER OUTAGES CAUSED BY
DOWNED TREE BRANCHES. STRONGEST WIND (BL IN EXCESS OF 30 KT) IS
CURRENTLY MODELED FOR THE DELMARVA IN THE 01Z-08Z/13 TIME FRAME.
AM EXPECTING WIDESPREAD GUSTS 35-45 MPH LATER WED NIGHT WITH THE
STRONGEST WIND ON THE DELMARVA WHERE GUSTS TO 50 MPH ARE POSSIBLE.

ANY LEFTOVER THUNDER-SVR RISK IN THE DELAWARE VALLEY THROUGH
DELAWARE SHOULD EXIT THE COAST AROUND 01Z. 12Z NAM SIMULATION
LOOKS A LITTLE SLOW BUT WE`LL REREVIEW THIS AFTN.

MODEL DIFFERENCES ON HOW FAST THE COLD AIR ARRIVES WILL RESULT IN
LOWER CONFIDENCE ON TIMING THE TEMPS FALLING BELOW FREEZING. FOR
NOW EXPECT A FASTER DROP WEDNESDAY NIGHT THAN OUR 930AM FCST.

THE QUESTION OF LEFTOVER MOISTURE YIELDING SNOW OR SNOW SHOWERS
PTNS OF E PA AND NNJ. AT THIS TIME SINCE THIS ISNT A MID LVL CLOSED
LOW AT OUR LATITUDE... NOT THINKING MUCH NEW SNOW COVER EXCEPT MAYBE
I80 NORTH. CONFIDENCE BELOW AVG ON ACCURATELY PREDICTING SNOW
ACCUM BUT AT THIS TIME...UNLIKELY TO HAVE MORE THAN A DUSTING
ANYWHERE EXCEPT THE POCONOS AND HIGH TERRAIN SUSSEX COUNTY WHERE
AN INCH OR 2 MAY OCCUR. DUE TO FLASH FREEZE N OF I80...CAN SEE
THE NEED FOR A WINTER WX ADVY FOR A SHORT PERIOD OF TIME
HIGHLIGHTING THE ISSUE.

WIND CHILL...10 BELOW IN THE POCONOS FOR A TIME THURSDAY MORNING.


THURSDAY...BLUSTERY AND VERY COLD FOR THE END OF WINTER DOWN HERE.
MANY NORTHWEST GUSTS NEAR 40 MPH WITH POTENTIAL FOR ISOLATED GUSTS
NEAR 50 MPH. MAX TEMPS GENERALLY AOB 30 EXCEPT DELMARVA. MAX`S AT
LEAST 20F BELOW NORMAL....POSSIBLY 25 BELOW NORMAL IN THE POCONOS.


FRIDAY...NOT AS COLD NOR AS WINDY WITH WIND SHIFTING TO SOUTHWEST
AND ONLY GUSTY TO 20-25 MPH DURING THE AFTERNOON.  WARM ADVECTION
CIRRUS DURING THE AFTN.

SATURDAY...VARIABLE CLOUDS AHEAD OF A CFP WITH A SMALL CHC OF A
LIGHT SHOWER.

SUNDAY...DRY AND COLDER.

MONDAY-TUESDAY OF NEXT WEEK...UNCERTAINTY...

&&

.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

TODAY...VFR. A COLD FRONT WILL MOVE INTO THE REGION EARLY THIS
MORNING AND WINDS WILL BACK TOWARDS THE WEST AND REMAIN UNDER 10
KNOTS. HIGH LEVEL CLOUDS WILL CONTINUE TO STREAM IN FROM THE WEST
WELL AHEAD OF THE NEXT LOW PRESSURE SYSTEM. SHOULD BE ABLE TO
REACH CONVECTIVE TEMPERATURES LATER THIS AFTERNOON SO A FEW
STRATOCU ARE POSSIBLE. ANOTHER CHANCE FOR A SEABREEZE TO DEVELOP
AND MOVE THROUGH ACY LATER THIS AFTERNOON.

TONIGHT...MOSTLY VFR. WINDS BECOME LIGHT AND VARIABLE FOR A TIME
AHEAD OF THE NEXT SYSTEM....ULTIMATELY VEERING TOWARDS THE
SOUTHEAST. WILL START TO SEE THE LOWERING CLOUD BASES TOWARDS MVFR
LATE TONIGHT.

WEDNESDAY...VFR AND EVEN BRIEF IFR CONDITIONS WILL BE POSSIBLE
UNDER THE HEAVER SHOWERS EXPECTED THROUGH THE DAY WEDNESDAY.
ISOLATED TSRA IS ALSO POSSIBLE WEDNESDAY AFTERNOON.

OUTLOOK...
WEDNESDAY NIGHT...MVFR AND EVEN BRIEF IFR CONDITIONS WILL BE POSSIBLE
DURING THE EVENING IN SHOWERS. A COLD FRONT WILL PRODUCE AN ABRUPT
CHANGE WITH GUSTY WESTERLY AND NORTHWESTERLY WINDS WEDNESDAY
EVENING. A LINE OF TSRA WITH GUSTY WINDS IS POSSIBLE WITH THIS
FRONT NEAR 00Z/13 ALONG THE COAST. HOWEVER, CONDITIONS SHOULD
IMPROVE TO VFR WITHIN HOURS OF THE FRONTAL PASSAGE. NORTHWEST
WINDS GUST 28-38 KT....ISOLATED 42 KT VCNTY KILG/KRDG AND KMPO.

THURSDAY...VFR SCT-BKN AOA 3500 FT. NW WIND GUST 30-38KT WITH
ISOLATED 40 KT POSSIBLE DURING THE MORNING.

FRIDAY...VFR CIRRUS WITH SW WIND GUST 15-20 KT DURING THE
AFTERNOON.

SATURDAY...MVFR CONDITIONS POSSIBLE IN SHRA PRIMARILY AT KABE AND
KRDG. OTHERWISE VFR CONDITIONS EXPECTED.  WSHIFT FROM SW TO NW.

SUNDAY...VFR. NW WIND GUST 20 KT.

&&

.MARINE...
SUB-ADVY CONDITIONS WILL PERSIST ON THE WATERS TODAY AND TONIGHT. A
WEAK COLD FRONT WILL CREEP INTO THE WATERS LATER THIS MORNING
BACKING WINDS TO THE WEST. WEAK HIGH PRESSURE WILL MOVE IN AHEAD
OF THE APPROACHING DEEPENING LOW PRESSURE ACROSS THE OHIO VALLEY
THIS EVENING. WINDS AND SEAS WILL RELAX BY THEN UNDER A LOOSE
PRESSURE GRADIENT. WINDS THEN VEER TOWARDS THE SOUTHEAST AND
INCREASE LATE TONIGHT AS THE LOW PRESSURE APPROACHES OUR REGION.

WEDNESDAY...WINDS INCREASING TO SCA AS A LOW APPROACHES THE REGION.

OUTLOOK...
WEDNESDAY NIGHT AND THURSDAY...GALE CONDITIONS EXPECTED BEHIND A
COLD FRONT THAT WILL PUSH THROUGH WEDNESDAY EVENING. WINDS NOT
EXPECTED TO SUBSIDE BELOW GALE UNTIL THURSDAY EVENING. LIGHT
FREEZING SPRAY LIKELY ON THE OCEAN WATERS DURING THURSDAY MORNING.

FRIDAY...CONDITIONS DECREASING BELOW SCA, BUT MAY APPROACH SCA
AGAIN ON FRIDAY NIGHT.

SATURDAY...SUB-SCA CONDITIONS WITH UNCERTAINTY.

SUNDAY...PROBABLY SUB SCA CONDITIONS.

&&

.HYDROLOGY...
SO FAR, QPF WITH THE MID WEEK SYSTEM LOOKS TO STAY LESS THAN ONE
INCH. HOWEVER, BRIEF, HEAVY DOWNPOURS UNDER THE THUNDERSTORMS ARE
POSSIBLE LEADING TO INCREASED RUNOFF, AND POSSIBLY A HIGHER THREAT
FOR MINOR FLOODING. HOWEVER, WHERE THIS WILL OCCUR IS STILL
UNCERTAIN. WE WILL CONTINUE TO MONITOR THE SITUATION.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY EVENING FOR
     ANZ430-431-450>455.
     SMALL CRAFT ADVISORY FROM NOON TO 6 PM EDT WEDNESDAY FOR
     ANZ430-431-450>455.

&&

$$
SYNOPSIS...DRAG  1215
NEAR TERM...HEAVENER/ROBERTSON
SHORT TERM...HEAVENER/JOHNSON
LONG TERM...DRAG 1215
AVIATION...DRAG/HEAVENER 1215
MARINE...DRAG/HEAVENER 1215
HYDROLOGY...