Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 282106
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
406 PM EST SUN DEC 28 2014

.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO PUSH FURTHER SOUTH OF OUR REGION
TONIGHT. THEN A WEAK AREA OF LOW PRESSURE MOVES ALONG THE FRONT,
STALLED TO OUR SOUTH, TOMORROW. COLD HIGH PRESSURE WILL RIDGE
ACROSS THE REGION TUESDAY AND REMAIN IN CONTROL OF THE WEATHER
THROUGH FRIDAY. A LOW PRESSURE SYSTEM AND WARM FRONT MAY ADVANCE
TOWARD OUR AREA NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
THE SURFACE COLD FRONT CONTINUES TO SLIDE TO OUR SOUTH AND EAST
WHILE DRIER SURFACE AIR IS PUSHING IN FROM THE NORTHWEST THIS
EVENING. REGIONAL RADAR IS SHOWING SOME ENHANCED RETURNS WITHIN THE
DRIER AIRMASS BUT GIVEN THAT THE RAIN SHOULD BE FALLING OUT OF AN
ALTOCU DECK, ITS DOUBTFUL ANY IS REACHING THE GROUND...WE ARE
BASICALLY POPLESS FROM THE PHILLY METRO NORTH AND WEST. THE MAIN
ACTION THIS EVENING AND TONIGHT WILL CONTINUE TO RESIDE ACROSS OUR
SOUTHERN ZONES, ALONG THE FRONTAL BOUNDARY WHERE MULTIPLE WAVES MOVE
OVERHEAD.

WE EXPECT LIGHT RAIN TO CONTINUE THROUGH THE LATE AFTERNOON HOURS
BEFORE DECREASING AHEAD OF THE NEXT MID-LEVEL WAVE. MOST OF THE
GUIDANCE HAS THE NEXT INCREASE IN POPS EXPECTED SHORTLY BEFORE
MIDNIGHT, BUT AS THE SURFACE FRONT SAGS FARTHER SOUTH, THE BETTER
CHANCES/QPF DO THE SAME.

TEMPERATURES TONIGHT SHOULD STILL BE WELL ABOVE AVERAGE WITH PLENTY
OF CLOUD COVER STILL IN PLACE AND A LAG IN THE PUSH OF THE REALLY
COLD AIR ALOFT. USED A BLEND OF THE MET/MAVMOS AS BOTH MODELS LOOKED
REASONABLE WITH THEIR THERMAL INITIALIZATIONS.

&&

.SHORT TERM /6 AM MONDAY THROUGH 6 AM MONDAY/...
CONTINUED RAIN THREAT ACROSS OUR EXTREME SOUTH AS THE LAST OF THE
MID-LEVEL WAVES NEARS LATE IN THE MORNING/EARLY AFTERNOON. AFTER
THIS WAVE WE SHOULD REALLY START TO DRY OUT EVERYWHERE AS MORE
ESTABLISHED ZONAL FLOW WITH RIDGING UPSTREAM TAKES OVER.
NORTH-NORTHWEST WINDS WILL ALLOW FOR CONTINUED DRYING AND
DOWNSLOPING FLOW MAY HELP TO BREAK THE CLOUD DECK LEAVING US WITH
PARTLY TO MOSTLY SUNNY SKIES. TEMPERATURES WILL BE SEVERAL DEGREES
COLDER THAN THE PAST COUPLE OF DAYS BUT WE COULD END UP BEING AT OR
SLIGHTLY ABOVE AVERAGE, ESPECIALLY IF WE GET AN ENHANCED DOWNSLOPE
FLOW TO HELP WARM US.

&&

.LONG TERM /MONDAY THROUGH SUNDAY/...
TWO MAIN PERIODS OF FOCUS IN THE LONG TERM. FIRST, THE SURFACE LOW
RIDING ON THE STALLED FRONT WHICH LIKELY WON/T BRING MUCH IN THE
WAY OF AN IMPACT TO US, BUT A FEW OUTLIER ENSEMBLE MEMBERS
CONTINUE TO DEPICT A SNOW EVENT FOR DELMARVA AND SOUTHERN NJ
MONDAY NIGHT THROUGH TUESDAY. SECOND IS THE SYSTEM NEXT WEEKEND.

FIRST IN THE MONDAY NIGHT AND TUESDAY TIME FRAME. CHANGED LITTLE
IN THE GOING FORECAST. MOST DETERMINISTIC MODELS, INCLUDING THE
GFS, ECMWF, AND CMC SHOW THE FRONT PUSHING FAR ENOUGH SOUTH OF OUR
REGION (GENERALLY FROM THE FL PANHANDLE TO THE COAST OF THE
CAROLINAS BY MONDAY EVENING) BEFORE THE SECONDARY LOW DEVELOPS
THAT OUR REGION WILL SEE LITTLE, IF ANY PRECIP. THIS SOLUTION
GENERALLY HAS PRECIP IN OUR REGION, IF ANY, CONFINED TO CENTRAL
DELMARVA. UNCERTAINTY COMES IN WITH SOME OF THE SREF MEMBERS, AND
TO A LESSER EXTENT THE NAM, HOLDING ON TO A SNOWIER SOLUTION
FOR MUCH OF OUR REGION SOUTH OF PHL. STAYED CLOSE TO THE PREVIOUS
FORECAST AND THE DRIER SOLUTION, FOR ONE BECAUSE THIS HAS BEEN
RATHER CONSISTENT THE LAST SEVERAL MODEL RUNS. ALSO, ALL THE
DETERMINISTIC MODELS, INCLUDING THE NAM, SHOW CONSISTENT 6 HR
PRESSURE RISES OF 3MB OR MORE IN THE WAKE OF THE FRONT THROUGH
MONDAY EVENING AT LEAST, SUGGESTING THE FRONT SHOULD BE ABLE TO
PUSH WELL SOUTH OF THE REGION BEFORE STALLING.

WEDNESDAY THROUGH FRIDAY STILL LOOK COOL AND TRANQUIL. FLOW ALOFT
STAYS MOSTLY ZONAL, MEANING WE WILL LIKELY NOT SEE THE BRUNT OF
THIS COLD AIR MASS. STILL, PORTIONS OF THE POCONOS AND NW NJ MAY
NOT MAKE IT ABOVE FREEZING UNTIL FRIDAY.

FRIDAY NIGHT THROUGH SUNDAY...STILL WATCHING A SYSTEM WHICH BY
FRIDAY IS MODELED TO BE A 500 MB CLOSED LOW OVER THE SW U.S.. THE
GFS AND ECMWF TRENDED CONSIDERABLY SLOWER WITH THE LOW FROM FRIDAY
THROUGH THE WEEKEND. NOT SURPRISING, GIVEN THAT THEY ALSO DEPICT
THE ROSBY NUMBER DECREASING THROUGH THIS TIME. OTHERWISE, THE GFS
STAYED PRETTY CLOSE TO WHAT PREVIOUS RUNS HAD WITH THE LOW LIFTING
TO THE GREAT LAKES REGION, RESULTING IN PRECIP FOR OUR REGION
MAINLY WITH IN THE WARM SECTOR (IN OTHER WORDS, MOSTLY RAIN). THE
ECMWF ON THE OTHER HAND, WHICH HAD BEEN SHOWING A TRACK SIMILAR TO
THE GFS YESTERDAY, NOW BRINGS THE LOW FROM SOUTHERN KY EAST TO SE
VA, LEAVING OUR REGION IN THE SECTION FOR WRAP AROUND (POTENTIALLY
WINTRY) PRECIPITATION. THE ECMWF SOLUTION IS FAR DIFFERENT THAN
THE TRACKS OF THE LAST SEVERAL SYSTEMS, BUT NOT TOTALLY OUT OF THE
QUESTION GIVEN THE LARGE SCALE PATTERN CHANGE IT IS MODELING (AS
SHOWN BY THE ROSBY WAVE PATTERN CHANGE). STILL, GIVEN HOW
STUBBORNLY THE PATTERN HAS HELD THIS WINTER, AM HESITANT TO
FORECAST SUCH A DRASTIC CHANGE WHEN IT IS STILL 5 TO 6 DAYS OUT.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

TODAY - TONIGHT...VFR. LIGHT NORTHWESTERLY WINDS AROUND 8 KNOTS.
CONTINUED SHOWER THREAT FROM PHL SOUTHWARD WITH A SOUTHERN SHIFT
EXPECTED THROUGH TONIGHT. CONFIDENCE: HIGH.

MONDAY...VFR. WINDS VEER TOWARDS THE NORTH FOR A TIME BEFORE BACKING
TOWARDS THE NORTHWEST LATE IN THE CYCLE. WE SHOULD BE PRECIPITATION
FREE TOMORROW.

OUTLOOK...
MONDAY NIGHT THROUGH TUESDAY...VFR CONDITIONS EXPECTED FROM KPHL
AND NORTH. AT KACY...KMIV...AND KILG THERE IS A RISK OF MVFR
CEILINGS AT TIMES.

TUESDAY NIGHT THROUGH FRIDAY...MOSTLY VFR CONDITIONS EXPECTED.

&&

.MARINE...
TODAY - MONDAY...SUB-SCA CONDITIONS EXPECTED. SEAS WILL CONTINUE
AROUND 3 TO 4 FEET. SOUTHWEST WINDS VEER NORTHWEST LATER TONIGHT BUT
REMAIN LIGHTER, 10 TO 15 KNOTS. CONTINUED VEERING TOWARDS THE
NORTH-NORTHEAST IS EXPECTED BY TOMORROW.

OUTLOOK...
MONDAY NIGHT AND TUESDAY...OCCASIONAL GUSTS NEAR 25 KT ARE
POSSIBLE ON THE ATLANTIC COASTAL WATERS. OTHERWISE, CONDITIONS ARE
EXPECTED TO STAY BELOW SCA THRESHOLDS.

WEDNESDAY...SUB SCA CONDITIONS EXPECTED.

THURSDAY AND THURSDAY NIGHT...WESTERLY WINDS WITH GUSTS NEAR 25KT
ARE POSSIBLE, PRIMARILY ON THE ATLANTIC COASTAL WATERS.

FRIDAY...SUB SCA CONDITIONS EXPECTED.

&&

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

&&

$$
SYNOPSIS...JOHNSON
NEAR TERM...HEAVENER
SHORT TERM...HEAVENER
LONG TERM...JOHNSON
AVIATION...HEAVENER/JOHNSON
MARINE...HEAVENER/JOHNSON





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