Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 231336
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
936 AM EDT MON MAR 23 2015

.SYNOPSIS...
HIGH PRESSURE CENTERED NEAR THE UPPER GREAT LAKES WILL EXPAND
SOUTHEASTWARD AND OVER OUR AREA THROUGH TUESDAY. A WARM FRONT
ARRIVES ON WEDNESDAY, FOLLOWED BY A STRONG COLD FRONT THURSDAY
NIGHT. HIGH PRESSURE THEN STARTS TO BUILD TOWARD THE MID ATLANTIC
SATURDAY INTO SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE OVER THE GREAT LAKES REGION WILL CONTINUE TO EXPAND
SOUTHEASTWARD AND OVER OUR AREA TODAY. THIS WILL ALLOW FOR LESS WIND
COMPARED TO YESTERDAY. THE AIRMASS IS COLD THOUGH AND WITH LESS
MIXING THE TEMPERATURES WILL PROBABLY BE A BIT SLOWER TO RESPOND TO
THE SUNSHINE THIS MORNING. THIS WAS ACCOUNTED FOR IN THE UPDATED
HOURLY TEMPERATURE GRIDS.

AN UPPER-LEVEL TROUGH REMAINS ACROSS THE EAST AND A STRONG SHORT
WAVE IS ROUNDING THE TROUGH IN NEW ENGLAND. SIMILAR TO YESTERDAY, A
SMALL AREA OF SNOW SHOWERS IS SETTLING SOUTH-SOUTHEASTWARD INTO
NORTHEAST PENNSYLVANIA, HOWEVER THESE SHOULD CONTINUE TO WEAKEN
BEFORE REACHING THE POCONOS. OTHERWISE, SOME FLAT STRATOCUMULUS
ESPECIALLY UP NORTH HOWEVER THIS SHOULD BE LIMITED GIVEN HOW DRY THE
AIRMASS IS ESPECIALLY BELOW 850 MB /VIA THE 12Z STERLING, VA RAOB/.
SOME HIGH LEVEL CLOUDS BRUSHING MOSTLY OUR SOUTHERN AREAS AT TIMES
AS A SHEARING SHORT WAVE PASSES WELL TO OUR SOUTH.

NO CHANGES WERE MADE ATTM TO THE HIGH TEMPERATURES.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
THE AFOREMENTIONED HIGH MOVES EVEN CLOSER OVERNIGHT
AND A DRY FCST IS IN STORE.  THE WIND SHUD GENLY BE LIGHT, BUT A
S/WV IS EXPECTED TO MOVE ACRS SRN AREAS AND THIS WILL CAUSE AN
INCREASE IN CLOUDS.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
TUESDAY...ONE LAST QUIET BUT COOL DAY IS ON TAP AS THE SURFACE
HIGH WILL BE RIGHT OVER THE REGION BEFORE SHIFTING OFF SHORE
TUESDAY NIGHT.

WEDNESDAY...THE MAIN QUESTION THROUGH THIS DAY WILL BE THE TIMING OF
THE WARM FRONT AND HOW MUCH, IF ANY, PRECIP WE WILL HAVE WITH THE
INITIAL FRONTAL PASSAGE. OF NOTE WITH TODAY/S MODEL RUNS IS THE
TREND TOWARDS DRIER WITH THE INITIAL WARM FRONT PASSAGE. THE
NAM, ECMWF, AND CMC ALL SHOWED THIS TREND, ALTHOUGH TO VARYING
DEGREES, OVER THE LAST FEW MODEL RUNS. GFS HAD BEEN SHOWING THIS
TREND, BUT TRENDED BACK TO WETTER WITH THE 00Z RUN. RELATED TO
THIS, THE PREVIOUSLY MENTIONED MODELS NOW SHOW THE INITIAL LOW
SURFACE LOW AND UPPER LEVEL SHORT WAVE TROUGH ASSOCIATED WITH THE
WARM FRONT TRACKING FURTHER NORTH.

WEDNESDAY NIGHT INTO THURSDAY...BY WEDNESDAY NIGHT THE SECONDARY
SURFACE LOW AND UPPER LEVEL SHORT WAVE TROUGH BEGIN THEIR APPROACH
TOWARDS THE REGION, AND WITH PLENTY OF MOIST AIR IN PLACE, SHOULD
RESULT IN WIDESPREAD RAIN ACROSS THE REGION. CONTINUED
SOUTHWESTERLY FLOW SHOULD HELP TO WARM THE LOW LEVELS AND INCREASE
INSTABILITY. EVEN SO, MODEL CAPE VALUES, EVEN FOR MU CAPE, ARE
LIMITED (GENERALLY LESS THAN 500 J/KG. THEREFORE, WHILE THERE IS
STILL A SMALL CHANCE FOR THUNDERSTORMS, WOULD NOT EXPECT
WIDESPREAD THUNDERSTORMS ACROSS THE REGION UNLESS THERE IS MORE
WARM AIR ADVECTION IN THE LOW LEVELS AND THE COLD FRONT WILL HOLD
OFF IT`S ARRIVAL UNTIL VERY LATE IN THE DAY ON THURSDAY (A FEW 00Z
MODEL RUNS DID TREND THIS WAY). BULK SHEAR VALUES (FOR THE 0-6 KM
LAYER) LOOK TO BE NEAR 50 KT ESPECIALLY AS THE COLD FRONT
APPROACHES. SO IF STORMS DO DEVELOP, A FEW STRONG STORMS ARE NOT
OUT OF THE QUESTION DESPITE THE LIMITED CAPE VALUES. COLD FRONT IS
EXPECTED TO QUICKLY SWEEP THROUGH EITHER THURSDAY EVENING OR
OVERNIGHT.

FRIDAY THROUGH SUNDAY... BOTH THE GFS AND ECMWF CONTINUED THE
TREND STARTED YESTERDAY WITH DRY AIR ADVECTION DOMINATING ANY LIFT
ASSOCIATED WITH THE TRAILING UPPER LEVEL TROUGH. ALSO, MOST MODELS
AND ENSEMBLE MEMBERS NOW SHOW THE COASTAL LOW TAKING A TRACK WELL
OUT TO SEA AT THIS TIME. GIVEN THE ROSSBY NUMBER OF 5 AND THE
RECENT PATTERN, WOULD THINK THIS WOULD BE A MORE PROGRESSIVE
PATTERN, THUS WOULD FAVOR THE LOW BEING WELL EAST OF THE REGION.
THEREFORE, TRENDED POPS DOWN THROUGH THIS PERIOD.

SUNDAY NIGHT AND MONDAY...A FAST MOVING UPPER LEVEL TROUGH COULD
CROSS THE REGION THROUGH THIS PERIOD, THOUGH THERE ARE
CONSIDERABLE DIFFERENCES IN THE TIMING BETWEEN THE GFS AND ECMWF.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE,
KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS.

REST OF TODAY...VFR WITH MAINLY SOME HIGH CLOUDS AT TIMES. NORTH-
NORTHEAST TO NORTHWEST WINDS MAINLY AROUND 10 KNOTS.

TONIGHT...VFR, WITH INCREASING CLOUDS AND A CEILING DEVELOPING.
NORTH-NORTHEAST WINDS LESS THAN 10 KNOTS.

OUTLOOK...
TUESDAY...VFR CONDITIONS EXPECTED.

WEDNESDAY...CEILINGS MAY BEGIN TO LOWER TO MVFR WITH RA.

THURSDAY...MVFR AND POSSIBLY IFR CEILINGS FOR MUCH OF THE DAY.
VISIBILITY RESTRICTIONS IN SHRA AND ISOLATED TSRA POSSIBLE AS
WELL. GUSTY WINDS POSSIBLE BEHIND A COLD FRONT LATE ON THURSDAY.

FRIDAY...CEILINGS EXPECTED TO GRADUALLY INCREASE TO VFR.

&&

.MARINE...
A COLD BOUNDARY LAYER IS HELPING TO ALLOW FOR BETTER MIXING THIS
MORNING, WITH SOME GUSTS TO ABOUT 25 KNOTS AND HIGHER SEAS. THIS IS
ANTICIPATED TO BE SHORT IN DURATION AND MOSTLY FARTHER OFFSHORE,
THEREFORE HELD OFF ON A SMALL CRAFT ADVISORY ATTM.

OTHERWISE, HIGH PRESSURE WILL GENERALLY DOMINATE THROUGH TONIGHT.
OTHER THAN FOR A SHORT TIME THIS MORNING, WINDS AND SEAS ARE
EXPECTED TO BE BELOW SCA CRITERIA THROUGH TONIGHT.

OUTLOOK...
TUESDAY AND WEDNESDAY...WINDS AND SEAS ARE EXPECTED TO REMAIN
BELOW SCA CRITERIA.

THURSDAY AND FRIDAY...SOUTHWESTERLY WINDS WILL WILL QUICKLY
INCREASE ABOVE 25KT EARLY ON THURSDAY. WINDS WILL STAY GUSTY AND
SHIFT QUICKLY WITH A COLD FRONT EXPECTED LATE IN THE DAY ON
THURSDAY OR OVERNIGHT THURSDAY NIGHT. WINDS GUSTING TO NEAR 30 KT
POSSIBLE. SEAS WILL SUBSEQUENTLY INCREASE AND SCA CONDITIONS ARE
EXPECTED THROUGH THE DAY FRIDAY.

&&

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

&&

$$
SYNOPSIS...GORSE/JOHNSON
NEAR TERM...GORSE
SHORT TERM...NIERENBERG
LONG TERM...JOHNSON
AVIATION...GORSE/JOHNSON
MARINE...GORSE/JOHNSON/NIERENBERG


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