000
FXUS61 KPHI 191505
AFDPHI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1105 AM EDT FRI MAR 19 2010
.SYNOPSIS...
AN AREA OF HIGH PRESSURE NEAR THE CENTRAL GULF COAST WILL SLIDE
EASTWARD THROUGH TONIGHT, AND GRADUALLY MOVE OFF THE EAST COAST
LATER SATURDAY. MEANWHILE, A WEAK COLD FRONT WILL BE SETTLING
SOUTHEASTWARD FROM CANADA AND NEW ENGLAND SATURDAY. THIS FRONT LOOKS
TO STALL NEAR OUR AREA LATE SATURDAY AND SUNDAY AS A STRONG STORM
SYSTEM ORGANIZES ACROSS THE CENTRAL AND SOUTHERN PLAINS. THIS SYSTEM
WILL SLOWLY MOVE EASTWARD AND ARRIVE IN OUR AREA MONDAY, THEN MOVE
AWAY DURING TUESDAY. HIGH PRESSURE THEN SETTLES IN FOR WEDNESDAY AND
THURSDAY, ALTHOUGH A COLD FRONT MAY APPROACH THURSDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
OTHER THAN A FEW AC AND CI, SKIES WERE CLEAR OVER THE FORECAST
AREA LATE THIS MORNING. NOT MUCH CHANGE EXPECTED IN THE SKY COVER
THIS AFTERNOON. THAT WILL MEAN PLENTY OF SUNSHINE TO WARM US INTO
THE 60S AND LOWER 70S WHICH IS MUCH ABOVE NORMAL FOR THIS TIME OF
YEAR. WE DO EXPECT A SEABREEZE TO SET IN ALONG OUR COASTAL OCEAN
AREAS. ONCE THAT OCCURS, TEMPERATURES WILL DROP A BIT SINCE THE
WATER TEMPERATURES ARE STILL QUITE LOW.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
THE STRETCH OF WARM WEATHER FOR MOST WILL CONTINUE DURING THIS TIME
FRAME AS A MIDLEVEL RIDGE MOVES ACROSS THE AREA SATURDAY. THE ONLY
FLY IN THE OINTMENT THOUGH WILL BE A FRONTAL BOUNDARY SITUATED TO
OUR NORTH. THIS BOUNDARY WILL TRY AND SETTLE SOUTHWARD DURING
SATURDAY INTO AT LEAST A PART OF OUR AREA, HOWEVER IT REALLY DOES
NOT LOOK ALL THAT WELL DEFINED. AT THE SAME TIME, STRONG ENERGY
EJECTING OUT INTO THE SOUTHERN PLAINS WILL ORGANIZE A SURFACE LOW.
THIS FEATURE WILL PROBABLY TEND TO HANG UP THE FRONT TO OUR NORTH
AFTER AWHILE AS OUR FLOW CONTINUES TO BE SOUTHWESTERLY ESPECIALLY
ALOFT.
OUR SENSIBLE WEATHER LOOKS TO CONSIST OF MOSTLY JUST A GRADUAL
INCREASE IN SOME HIGH CLOUDS SATURDAY AND ESPECIALLY SUNDAY. THE
TREND THIS WINTER HAS BEEN FOR MIDLEVEL ENERGY TO END UP BEING
STRONGER AND CLOSING OFF WITH TIME. THIS LATEST SYSTEM LOOKS TO
FOLLOW THIS AS THE SOUTHERN ENERGY IS STRONG AND AMPLIFIES THE
UPPER-LEVEL TROUGH. THIS WILL HOLD THINGS BACK LONGER TO OUR WEST,
ALLOWING MOST AREAS TO SQUEEZE IN ANOTHER NICE DAY SUNDAY.
THE ONLY POSSIBLE EXCEPTION IS THE NORTHWESTERN ZONES AS SOME WEAK
LIFT MAY GENERATE A FEW SHOWERS OR SPRINKLES. WE CONFINED SOME
SLIGHT CHC AND LOW CHC POPS ACROSS THE FAR NORTHWEST AREAS SUNDAY
AFTERNOON. WE WILL HAVE TO MONITOR THE POSSIBLE BACKDOOR FRONT,
HOWEVER AS OF NOW IN GENERAL WE CONTINUE TO NOT HIT THIS FEATURE ALL
THAT HARD.
AS FOR TEMPERATURES, WE GENERALLY BLENDED THE NAM/GFS MOS ALTHOUGH
DID GO A LITTLE ABOVE ON THE MAXIMUM TEMPERATURES FOR SOME LOCALES
ESPECIALLY THE MORE URBAN AREAS. THE LOW-LEVEL FLOW GRADUALLY
INCREASES SATURDAY AND SUNDAY, WHICH MAY TEND TO LIMIT THE
DEVELOPMENT OF A SEA BREEZE, ALTHOUGH MORE OF A SOUTHERLY SYNOPTIC
WIND IS FORECAST WHICH MAY BE ENOUGH TO KEEP IT COOLER RIGHT ALONG
THE COAST. AS A SIDE NOTE, SPRING ARRIVES ON SATURDAY AT 132 PM.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THIS TIME FRAME WILL TRANSITION INTO ACTIVE WEATHER AFTER A NICE
BREAK. THE CONSENSUS OF THE MODEL GUIDANCE IS TO INDICATE A STRONGER
CLOSED LOW SLIDING ACROSS THE SOUTHERN PLAINS SUNDAY AND SUNDAY
NIGHT, THEN MOVING INTO THE MID ATLANTIC REGION MONDAY. INITIALLY
THIS SYSTEM LOOKED TO BE JUST A STRONG COLD FRONTAL PASSAGE FOR OUR
AREA, CENTERED ON SUNDAY NIGHT, HOWEVER THE TREND OF THIS WINTER
CONTINUES AS THE UPPER-LEVEL ENERGY BECOMES STRONG AND MORE CLOSED
OFF. THIS IS DUE TO THE NORTHERN AND SOUTHERN STREAM ENERGY
REMAINING MORE SEPARATE, THEREFORE THE SOUTHERN STREAM ENERGY
DOMINATES. THIS ALSO LEADS INTO A SLOWER SOLUTION, WHICH THE MODELS
HAVE BEEN TRENDING TOWARDS. THE SLOWER EASTWARD PROGRESSION OF THIS
SYSTEM SHOULD ALLOW FOR MORE MOISTURE RETURN. AS THIS SYSTEM WINDS
UP ACROSS THE SOUTHERN PLAINS AND GRADUALLY MOVES EASTWARD, THE
NORTHERN STREAM ENERGY WILL TRY AND DROP A WEAK COLD FRONT
SOUTHEASTWARD INTO SUNDAY NIGHT. THIS BOUNDARY LOOKS TO STALL NEAR
OUR AREA AREA DURING THAT TIME, AND IT APPEARS THAT THIS BOUNDARY IS
MOSTLY SHALLOW WITH NOT MUCH CHANGE IN AIRMASS.
AS THE STORM SYSTEM NEARS OUR AREA SUNDAY NIGHT, WE WILL SEE AN
INCREASE IN CLOUDS AS THE MOISTURE DEPTH BEGINS TO INCREASE SOME.
THE LOW TO MID LEVEL FLOW WILL INCREASE AHEAD OF THIS FEATURE, WHICH
WILL STRENGTHEN THE WAA AND MOISTURE ADVECTION. AS AMPLE LIFT
OVERSPREADS THE AREA MOSTLY ON MONDAY, NUMEROUS SHOWERS ARE
EXPECTED TO DEVELOP. THE MODEL GUIDANCE DOES NOT REALLY SHOW THE
STALLED SURFACE FRONT ALL THAT WELL, WHICH ALLOWS US TO BELIEVE THAT
IT IS RATHER WEAK THIS FAR SOUTH. DEPENDING ON WHERE THIS BOUNDARY
IS THOUGH, MAY ALLOW FOR SOME ENHANCED LIFT. THE FORECAST SOUNDINGS
CONTINUE TO INDICATE SOME ELEVATED CAPE DEVELOPING SUNDAY INTO
MONDAY. THE ATMOSPHERIC PROFILE CONTINUES TO BECOME RATHER
SATURATED THEREFORE THE CAPE PROFILE IS SKINNY. WE CANNOT RULE
OUT SOME ISOLATED TO SCATTERED CONVECTION OCCURRING. AS A RESULT, A
CHC OF THUNDER WILL CONTINUE TO BE CARRIED FOR MOST AREAS ALTHOUGH
WE WILL MOVE IT FROM SUNDAY NIGHT TO MONDAY. THE 850 MB DEW POINTS
ARE FORECAST TO INCREASE TO NEAR +10C FOR A TIME AHEAD OF THE SYSTEM
WITH THE PW VALUES RISING TO AROUND AN INCH. AS A RESULT, HEAVIER
DOWNPOURS WILL BE POSSIBLE AND IF THIS TENDS TO BE MORE WIDESPREAD,
WE WILL HAVE TO MONITOR THE POTENTIAL FOR A RENEWED FLOOD THREAT AS
SOME RIVER/CREEKS ARE STILL RUNNING RATHER HIGH. OVERALL, WE
CONTINUED WITH THE RAMPING UP OF POPS TO HIGH LIKELY, BUT JUST
SLOWED THIS DOWN SOME.
AS THE SYSTEM GRADUALLY PULLS AWAY DURING TUESDAY, THE SHOWER CHCS
WILL BE ON THE DECREASE. SOME RIDGING IS THEN FORECAST TO FOLLOW
THIS SYSTEM WEDNESDAY AND THURSDAY AND HIGH PRESSURE BUILDS IN. THIS
LOOKS TEMPORARY THOUGH AS ENERGY DIVES INTO THE MIDWEST AND ALSO
EJECTS INTO THE CENTRAL PLAINS WEDNESDAY. THIS WILL EVENTUALLY TOSS
A COLD FRONT OUR WAY THURSDAY, ALTHOUGH DEPENDING ON HOW THE
NORTHERN AND SOUTHERN STREAMS BEHAVE, WE MAY HAVE ANOTHER CLOSED LOW
ON OUR HANDS WITH AN ASSOCIATED SURFACE LOW. FOR NOW, WE WILL
MAINTAIN THE LOW CHC POPS ON THURSDAY. THAT IS ALL FOR NOW. THANKS
TO THE SURROUNDING OFFICES FOR THE COLLABORATION EARLY THIS MORNING.
HAVE A GOOD ONE!
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.
VFR CONDITIONS ARE FORECAST THROUGH THE TAF PERIOD, WITH ONLY SOME
WISPS OF CIRRUS PASSING OVERHEAD AT TIMES. WINDS AT MOST LOCATIONS
WILL BE RATHER LIGHT, PERHAPS BACKING FROM NORTHWEST TO SOUTHWEST
THROUGH THE PERIOD. WE WILL FORECAST THE SEA BREEZE TO MAKE IT TO
ACY FOR A FEW HOURS AGAIN THIS AFTERNOON, BUT CONFINE IT TO THAT
LOCATION.
OUTLOOK...
DRY WEATHER SHOULD CONTINUE THROUGH SATURDAY. AS A FRONTAL BOUNDARY
DROPS DOWN FROM THE NORTH ON SATURDAY NIGHT AND AS LOW PRESSURE
APPROACHES FROM THE SOUTHWEST EARLY IN THE NEW WEEK, WE HAVE THE
POSSIBILITY OF SOME RAIN OR RAIN SHOWERS ON SUNDAY /ESPECIALLY
NORTHWEST/, MONDAY AND TUESDAY. THE BEST CHANCES FOR RAIN ARE ON
MONDAY.
&&
.MARINE...
BENIGN CONDITIONS ON THE WATERS ARE FORECAST THROUGH SUNDAY. A COLD
FRONT FROM THE NORTH IS FORECAST TO DROP INTO OR NEAR OUR REGION ON
SATURDAY NIGHT OR SUNDAY. LOW PRESSURE FROM THE SOUTHWEST IS
EXPECTED TO ARRIVE ON MONDAY NIGHT OR TUESDAY. AS THE LOW APPROACHES
AND PASSES NEARBY, WE MAY AGAIN EXPERIENCE SMALL CRAFT ADVISORY
CONDITIONS FOR A TIME FROM MONDAY INTO TUESDAY. THERE IS AN OUTSIDE
CHANCE OF GALE FORCE CONDITIONS IN THE WAKE OF THE LOW PER THE
ECMWF, BUT WE'RE NOT FORECASTING THAT WITH THIS PACKAGE.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...GORSE
NEAR TERM...GORSE/RPW
SHORT TERM...GORSE
LONG TERM...GORSE
AVIATION...DELISI/IOVINO
MARINE...DELISI
