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Area Forecast Discussion
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000
FXUS61 KPHI 182218
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
618 PM EDT WED MAR 18 2015

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN ACROSS THE MIDDLE ATLANTIC AND
NORTHEAST STATES TONIGHT THROUGH THURSDAY NIGHT. LOW PRESSURE WILL
DEVELOP OVER THE CAROLINAS ON FRIDAY AND DEEPEN OFF THE COAST
FRIDAY NIGHT AND SATURDAY. A COLD FRONT WILL CROSS THE REGION
SATURDAY NIGHT. HIGH PRESSURE WILL BUILD BACK ACROSS THE AREA
SUNDAY AND REMAIN INTO THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
SKIES SHOULD CLEAR OR CONTINUE CLEAR THIS EVENING WITH GUSTY
WINDS DIMINISHING STEADILY AROUND OR SHORTLY AFTER SUNSET.

THE FCST IS THE COLDEST OF THE AVBL MOS GUIDANCE BUT NO SPECIAL
RADIATIONAL ADDED SINCE THERE SEEMS TO BE SOME LIGHT NW BREEZE
THROUGH THE NIGHT.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
THURSDAY...MOSTLY SUNNY. (THIN CIRRUS AT TIMES). CLOSE TO
CONTINUITY OF THIS MORNINGS 330 AM FCST AND USED THE WARMER THE
12Z/18 GFS/NAM MOS GUIDANCE, SHADED TO THE ECMWF 2M 18Z/19 TEMPS
(PLUS 4-5F), AS ISSUED WITHIN THE 12Z/18 ECMWF OPERATIONAL CYCLE.
N-NW WINDS 10-15 MPH LESS AS COMPARED TO WHAT OCCURRED TODAY.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
THU NIGHT...HIGH PRESSURE WILL BE CRESTING ACROSS THE AREA THU
NIGHT. SKIES WILL BE PARTLY CLOUDY TO MOSTLY CLR EARLY...THEN
INCREASING CLOUDS OVERNIGHT. LIGHT PRECIPITATION ARRIVES ACROSS
THE ERN SHORE COUNTIES OF MD BEFORE DAWN FRI...BUT NOTHING
SIGNIFICANT IN THE WAY OF QPF BEFORE 12Z FRI. IT WILL BE A COOL
NIGHT WITH LOWS IN THE UPPER 20S/LOW 30S SOUTH AND UPPER TEENS TO
MID 20S NORTH.

FRI AND FRI NIGHT... LOW PRESSURE DEEPENS OVER THE CAROLINAS THEN
MOVES NORTH/NORTHEAST OFF THE COAST. PRECIPITATION OVERSPREADS THE
REST OF THE FORECAST AREAS FRI MORNING AND THE EVENT LASTS THE
REST OF THE DAY AND THE FIRST PART OF THE NIGHT. P-TYPES AT THE
ONSET WILL BE MOSTLY SNOW...BUT AS THE DAY PROGRESSES...THE
SOUTH/EAST AREAS WILL CHANGE TO RAIN. THIS TRANSITION AREAS WILL
THEN PROGRESS N/W ACROSS THE DEL VALLEY AND UP INTO THE LEHIGH
VALLEY. THERE STILL EXISTS PLENTY OF UNCERTAINTY WITH REGARDS TO
SNOWFALL AMOUNTS BEFORE ANY TRANSITION...THIS BEING SAID...OUR
PRESENT FCST HAS SNOW AMTS SIMILAR TO THE PREVIOUS ONES...AND THEY
MOSTLY ALIGN WITH THE WWD. THERE COLD BE SOME 4 TO 6 INCH AMTS
ACROSS THE SRN POCONOS...TAPERING DOWN TO 1-2 INCHES ACROSS THE
DEL VALLEY AND THE LESS THAN AN INCH ACROSS SRN NJ AND MUCH OF
DEL. MUCH OF THE SNOW ON THE SRN/ERN AREAS MAY FALL IN THE MORNING
AND THEN LARGELY MELT DURING THE AFTERNOON. BE AWARE OF FUTURE
SNOW FSTS AND POSSIBLE WSW FLAGS OVERNIGHT. FCST CONFID IN SNOW
AMOUNTS IS LOW/MODERATE ATTM.

SAT AND SAT NIGHT... THE LOW PRESSURE SYSTEM WHICH CAUSES ALL THE
SNOW FRI WILL BE WELL NORTH/EAST OF THE REGION SAT. ANOTHER LOW
MOVING ACROSS CANADA WILL CAUSE A COLD FRONT TO CROSS THE AREA SAT
EVENING/NIGHT. A REINFORCING SHOT OF COLD AIR WILL ARRIVE BEHIND
IT. SCT SHOWERS WILL ACCOMPANY THE FRONT. HIGHS SAT MOSTLY IN THE
MID/UPPER 40S WITH LOW 40S NORTH.

SUN THRU TUE...MORE HIGH PRESSURE BEGINS TO BUILD IN SUN AND IT
PERSISTS INTO TUE. A MOSTLY DRY FCST IS EXPECTED WITH TEMPERATURES
MOSTLY BELOW NORMAL. THE 12Z GFS INDICATES THAT A LOW COULD GRAZE
THE SRN AREAS MON NIGHT AND TUE...BUT THE 12Z HAS THE SYSTEM MUCH
FURTHER AND THERE IS LOW CONFID IN ITS POSITIONS ATTM. WE WILL
KEEP POPS SUB-14 PCT FOR NOW.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

TONIGHT...VFR CLEAR OR SCT CLOUDS AOA 20000 FT. NW WIND GUSTS
DIMINISH UNDER 10 KT. CONFIDENCE: ABOVE AVERAGE.

THURSDAY...VFR THIN SCT-BKN CLOUDS AOA 20000 FT. NW WIND GUST
AROUND 15-20 KT. CONFIDENCE: ABOVE AVERAGE.

OUTLOOK...

THURSDAY NIGHT...VFR. INCREASING CLOUDS OVERNIGHT

FRIDAY...DIMINISHING CONDITIONS TO MVFR/IFR. PRECIPITATION
STARTING AS SNOW, THEN POSSIBLY CHANGING TO RAIN SOUTH AND EAST OF
PHL. PRECIPITATION MAY STAY ALL SNOW NORTH AND WEST OF PHL.
 
FRIDAY NIGHT...PRECIPITATION SHOULD END DURING THE EVENING.
IFR/MVFR CONDITIONS MAY LINGER INTO THE NIGHT.
 
SATURDAY-SATURDAY NIGHT...CONDITIONS IMPROVING TO VFR. COLD FRONT
EXPECTED SATURDAY NIGHT, WITH SCATTERED SHOWERS POSSIBLE.

SUNDAY INTO MONDAY...VFR. GUSTY NORTHWEST WINDS AROUND 20 KT
POSSIBLE SUNDAY.

&&

.MARINE...
SCA THROUGH 04Z FOR THE NNJ WATERS, ESPECIALLY ANZ450 FOR NW WIND
GUSTS 25-30 KT.

SCA NOT ANTICIPATED IN ANY OF OUR WATERS LATE TONIGHT AND
THURSDAY THOUGH THERE IS A SMALL CHANCE ANZ 450 WILL SEE A FEW
GUSTS TO NEAR 25 KT ON THURSDAY.


OUTLOOK...

THURSDAY NIGHT...SUB-SMALL CRAFT ADVISORY CONDITIONS EXPECTED.
 
FRIDAY-FRIDAY NIGHT...POOR WEATHER FRIDAY...THEN LOW END SMALL
CRAFT ADVISORY CONDITIONS FRI NIGHT FOR SEAS (OCEAN) AS LOW
PRESSURE PASSES JUST TO THE EAST.

SATURDAY-SATURDAY NIGHT...LOW END SCA CONDITIONS SAT/SAT NIGHT
FOR SEAS ON THE OCEAN.

SUNDAY AND MONDAY...SUB-SCA CONDITIONS. FAIR WEATHER.

&&

.CLIMATE...
SNOW ON FRIDAY WHILE SIGNIFICANT IN PORTIONS OF OUR AREA, IS NOT
EXPECTED TO EXCEED RECORD VALUES.

FOR PERSPECTIVE: MARCH 20 DAILY RECORD SNOWFALL VALUES FOLLOW

1958 WAS THE YEAR. 

KABE 16.5 - 1958
KACY  5.0 - 1958
KILG 10.3 - 1958
KPHL  9.6 - 1958

LATEST OCCURRENCE OF MEASURABLE SNOW AND AMOUNT DURING THE
2013-2014 WINTER FOLLOWS...

KABE - 4/15/14 0.3" 
KACY - 3/16/14 0.3" 
(NOTE: LATEST OCCURRENCE ON RECORD IS 4/24/56 0.4") 
KPHL - 3/25/14 0.4" 
KILG - 3/25/14 0.7"

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ450-451.

&&

$$

SYNOPSIS...O'HARA
NEAR TERM...DRAG
SHORT TERM...DRAG
LONG TERM...O'HARA
AVIATION...DRAG/O'HARA
MARINE...DRAG/O'HARA
CLIMATE...FRANCK/DRAG



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