Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KPHI 201829
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
229 PM EDT WED AUG 20 2014

.SYNOPSIS...
LOW PRESSURE IN GREAT LAKES REGION WILL WEAKEN AS IT MOVES TO NEAR LAKE
ONTARIO THURSDAY. A SECOND AREA OF LOW PRESSURE WILL DEVELOP NEAR
THE CHESAPEAKE BAY THURSDAY NIGHT. HIGH PRESSURE IN EASTERN CANADA
WILL BUILD DOWN ALONG THE EAST COAST LATER THIS WEEKEND INTO NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
A WEAK SHORT MOVING ESEWD THRU NORTHERN PA SHOULD SHOVE THE BAND OF
SHOWERS AND ISOLATED TSTMS IN CENTRAL PA EWD INTO PARTS OF OUR
AREA THIS EVENING AND TONIGHT WITH A TENDENCY FOR THE BAND TO
PROBABLY DIMINISH DURING THE NIGHT. STILL A PWAT OF 1.5" PLUS
PERMITS SOME OF THE SHOWERS THIS EVENING TO BE POTENTIALLY BRIEFLY
HEAVY IN E PA.

FORECAST BASIS: POPS WERE BLENDED NCEP MOS POPS WITH THE 09Z SREF AND
THAT GIVES THE BEST CHANCE FOR SOME NEEDED RAIN TO E PA. OTRW A 50
50 BLEND OF 12Z/20 NCEP MOS EXCEPT BLENDED RGEM SKY WITH NAM SKY
AND GFS MOS GUIDE.

NEAR OR SLIGHTLY ABOVE NORMAL TEMPS.

&&

.SHORT TERM /THURSDAY/...
THURSDAY...ANOTHER SHORT WAVE IN THE WNW FLOW OVER SOUTHERN NEW
YORK STATE SHOULD REDEVELOP HEAVY CONVECTION DURING THE AFTN OVER
E PA...POSSIBLY EXTENDING INTO W NJ AND THE MD E SHORE CLOSER TO THE
CONVERGENCE OF THE SFC LOW AND INVERTED TROUGH EXTENDING NWD FROM
THE VCNTY OF DCA. PWAT VALUES ARE GENERALLY FORECAST AROUND
1.5-1.75 INCHES, SO SOME SHOWERS/STORMS COULD PRODUCE A PERIOD OF
MODERATE TO HEAVY RAINFALL. ISOLATED SMALL HAIL NOT IMPOSSIBLE AS
TT NEAR 50 IN AREA OF MAX INSTABILITY IN NJ (NEAR THE DELAWARE
RIVER).

FORECAST BASIS: POPS WERE BLENDED NCEP MOS POPS WITH THE 09Z SREF AND
THAT GIVES THE BEST CHANCE FOR SOME NEEDED RAIN TO E PA. OTRW A 50
50 BLEND OF 12Z/20 NCEP MOS EXCEPT BLENDED RGEM SKY WITH NAM SKY
AND GFS MOS GUIDE.

NEAR OR SLIGHTLY ABOVE NORMAL TEMPS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THE LONG TERM FORECAST STARTS OFF WITH RAIN CHANCES, BEFORE A DRYING
OUT PERIOD SETS IN ACROSS THE AREA.

THURSDAY NIGHT...A SECOND AREA OF SURFACE LOW PRESSURE IS FORECAST
TO DEVELOP NEAR THE CHESAPEAKE BAY ALONG THE STATIONARY BOUNDARY
TO OUR SOUTH. IT IS POSSIBLE THAT THIS MAY HELP KEEP A FOCUS FOR
PRECIPITATION THURSDAY NIGHT, BEFORE IT SAGS TO OUR SOUTH.

FOR FRIDAY INTO THE WEEKEND, THE MID/UPPER LOW WILL REMAIN TO OUR
NORTHEAST, KEEPING A NORTHWEST FLOW ALOFT ACROSS OUR AREA.
MEANWHILE, HIGH PRESSURE WILL BEGIN BUILDING DOWN ACROSS THE EAST
COAST FROM EASTERN CANADA. BEFORE THE HIGH TAKES FULL CONTROL OF THE
WEATHER, THERE WILL REMAIN A CHANCE OF SCATTERED SHOWERS FRIDAY AND
SATURDAY AS THERE MAY BE A FEW SHORT WAVE/VORT MAXES THAT AFFECT THE
AREA IN THE NORTHWEST FLOW ALOFT.

BY SUNDAY INTO EARLY NEXT WEEK, THE SURFACE HIGH BUILDS FURTHER INTO
THE MID-ATLANTIC REGION, WHICH SHOULD BRING DRY WEATHER TO THE AREA.

HIGHS ARE EXPECTED TO START OUT CLOSE TO OR SLIGHTLY ABOVE NORMAL
THURSDAY INTO FRIDAY, BUT AS THE HIGH BUILDS DOWN OUT OF EASTERN
CANADA AND THE NORTHWEST FLOW ALOFT REMAINS ACROSS THE AREA OVER THE
WEEKEND, 925/850 MB TEMPS AND THICKNESSES LOWER. THIS WILL ALLOW FOR
SLIGHTLY BELOW NORMAL TEMPERATURES OVER THE WEEKEND. AS WE MOVE INTO
EARLY NEXT WEEK, WE SHOULD START TO GET MORE OF A RETURN SURFACE
FLOW AND RIDGING ALOFT BEGINS TO TAKE PLACE ONCE AGAIN, ALLOWING
FOR REBOUNDING TEMPERATURES.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

REST OF TODAY...VFR SCT-BKN AOA 4000 FT. LIGHT SE TO S WIND.

TONIGHT...VFR CIGS AOA 4000 FT SPREAD EWD DURING THE NIGHT WITH A
PERIOD OF SHOWERS POSSIBLE. LIGHT SOUTH WIND.

THURSDAY...GENERALLY VFR CIGS. LIGHT SOUTH WIND. SCATTERED SHOWERS
AND THUNDERSTORMS WHICH MAY LOWER CIGS/VSBYS TO BRIEFLY IFR CONDITIONS.

OUTLOOK...
THURSDAY NIGHT...GENERALLY VFR. CHANCE OF SHOWERS AND THUNDERSTORMS
WHICH MAY LOWER CIGS/VSBYS.

FRIDAY-SUNDAY...PERIODS OF LOW END VFR OR MVFR CIGS POSSIBLE WITH A
CHANCE OF SHOWERS, ESPECIALLY FRIDAY INTO SATURDAY.

&&

.MARINE...
NO MARINE RELATED HEADLINES THROUGH THURSDAY.

EAST-SOUTHEAST WINDS BETWEEN 5-15 KT.

OUTLOOK...
THURSDAY-FRIDAY NIGHT...SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED.

SATURDAY-SUNDAY...SEAS MAY BEGIN TO APPROACH SMALL CRAFT ADVISORY
LEVELS AS A LONG FETCH DEVELOPS AROUND HIGH PRESSURE BUILDING IN
FROM THE NORTHEAST OUT OF EASTERN CANADA.

&&

.CLIMATE...
WE ARE AWARE HOW DRY ITS BEEN RECENTLY IN FAR NORTHERN NEW JERSEY...I80
NORTH AND IN FACT 70 TO 90 PCT OF NORMAL THERE THE PAST YEAR AND 5 O
25 PCT OF NORMAL THERE THE PAST MONTH. WHATEVER RAINFALL OCCURS THERE
NEEDS TO DEVELOP BETWEEN TONIGHT AND FRI EVENING...OTRW WE PROBABLY
NEED TO WAIT TIL THE END OF NEXT WEEK.

&&

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

&&

$$
SYNOPSIS...DRAG/ROBERTSON
NEAR TERM...DRAG  229
SHORT TERM...DRAG 229
LONG TERM...ROBERTSON
AVIATION...DRAG/ROBERTSON
MARINE...DRAG/ROBERTSON
CLIMATE...






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.