Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 272056
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
356 PM EST TUE JAN 27 2015

.SYNOPSIS...
A STRONG STORM SYSTEM EAST OF NEW ENGLAND TONIGHT WILL REACH THE
CANADIAN MARITIMES ON WEDNESDAY. HIGH PRESSURE WILL MOVE IN FROM
THE OHIO VALLEY WEDNESDAY AND SETTLE OVER THE REGION WEDNESDAY NIGHT
AND THURSDAY MORNING. LOW PRESSURE WILL MOVE THRU THE GREAT LAKES
ON THURSDAY AND REFORM EAST OF NEW ENGLAND ON FRIDAY. HIGH PRESSURE
WILL MOVE IN FROM THE GREAT LAKES ON SATURDAY...FOLLOWED BY A LOW
PRESSURE SYSTEM MOVING THROUGH THE APPALACHIANS EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
ALL WINTER STORM WARNINGS AND ADVISORIES WERE CANCELED EARLY THIS
AFTERNOON. SOME SCATTERED SNOW SHOWERS OR FLURRIES ARE POSSIBLE
EARLY THIS EVENING IN THE SOUTHERN POCONOS AND NORTHWEST NEW
JERSEY...BUT ANY SUCH ACTIVITY IS EXPECTED TO END BEFORE MIDNIGHT.
THE LOW PRESSURE SYSTEM RESPONSIBLE FOR THE WINTRY WEATHER THE PAST
DAY OR SO WILL CONTINUE TO MOVE SLOWLY NORTHEAST
OVERNIGHT...REACHING THE CANADIAN MARITIMES BY MORNING. SKIES ARE
EXPECTED TO GRADUALLY CLEAR FROM WEST TO EAST DURING THE OVERNIGHT
HOURS AS THIS LOW MOVES FURTHER AWAY. ON THE OTHER HAND, NORTHWEST
WINDS IN THE 10 TO 20 MPH RANGE...WITH HIGHER GUSTS...WILL CONTINUE
AS THE GRADIENT BETWEEN THIS LOW AND INCOMING HIGH PRESSURE FROM THE
WEST PERSISTS INTO WEDNESDAY. ONCE THE CLOUDS CLEAR...THE FRESH SNOW
COVER UP NORTH SHOULD ALLOW TEMPERATURES TO DROP INTO THE SINGLE
DIGITS. LOWS IN THE MID-TEENS TO AROUND 20 ARE EXPECTED FURTHER
SOUTH WERE THE SNOW COVER ISN/T AS DEEP OR WIDESPREAD. A BLEND OF
MAV/MET GUIDANCE WAS USED FOR OVERNIGHT TEMPERATURES, UNDERCUT BY A
DEGREE OR TWO UP NORTH TO ACCOUNT FOR SNOWCOVER.


&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
MOSTLY SUNNY CONDITIONS ARE EXPECTED...EXCEPT FOR MORNING
CLOUDINESS IN NORTHERN NJ (LINGERING EFFECTS FROM THE DEPARTING
LOW). NORTHWEST WINDS WILL PICKUP ONCE AGAIN AS DAYTIME MIXING TAKES
PLACE...THEN GRADUALLY DECREASE LATE IN THE DAY AS THE SUN BEGINS TO
SET AND AS THE PRESSURE GRADIENT CONTINUES TO DECREASE. TEMPS ARE
EXPECTED TO MAX OUT IN THE LOW TO MID 20S FAR NORTH, AND IN THE LOW
30S SOUTH. AGAIN...A BLEND OF MAV/MET GUIDANCE WAS USED FOR HIGH
TEMPERATURES WITH A SLIGHT CUT IN THE LOCATIONS OF DEEPER SNOWPACKS.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
THE MID LEVEL PATTERN AT 00Z THU IS COMPRISED OF A DEEP TROUGH AT
70W WITH A NORTHERN STREAM RIDGE ALONG THE BRITISH COLUMBIA COAST
AND A SOUTHERN STREAM CLOSED LOW INVOF THE CALIFORNIA COAST.
BETWEEN THESE TWO FEATURES...S/WV RIDGE WILL CREST OVER THE MID
ATL ON THU...THEN NORTHERN AND SOUTHERN STREAM S/WV ENERGY IS
PROGGED TO PHASE INVOF THE MISSISSIPPI VALLEY AND BECOME NEG
TILTED AS IT REACHES 70W AROUND 00Z SAT. THIS LEADS TO LOW
PRESSURE MOVING THRU THE GREAT LAKES ON THU WITH REDEVELOPMENT
CURRENTLY MODELED INVOF GEORGES BANK ON FRI. BY SAT...NORTHERN
STREAM S/WV ENERGY ENTERING THE NORTHERN PLAINS IS EXPECTED TO
INTERACT WITH SOUTHERN STREAM S/WV ENERGY EJECTING OUT OF A CLOSED
LOW INVOF THE FOUR CORNERS REGION. THIS LEADS TO A COMPLEX AREA OF
LOW PRESSURE...WHICH IS CURRENTLY PROGGED TO MOVE THRU THE
APPALACHIANS EARLY NEXT WEEK.

THE BEST CHANCES FOR PRECIP IN THE LONG TERM WILL BE THU NIGHT INTO
EARLY FRI AND THEN AGAIN EARLY NEXT WEEK...WITH PTYPE ISSUES LIKELY
WITH BOTH SYSTEMS...AS TEMPERATURES ROLLER COASTER FROM NEAR NORMAL
TO WELL BELOW NORMAL THROUGHOUT THE PERIOD.

DETAILS...

WED NIGHT AND THU...
GENERALLY TRANQUIL WEATHER AS A RIDGE OF HIGH PRES CRESTS OVER THE
REGION. EXPECTING IDEAL CONDITIONS FOR RADIATIONAL COOLING THU AM AS
ATMOS DECOUPLES WITH CLEAR SKIES...LIGHT WINDS...AND FRESH SNOW
COVER. EXPECTING MIN TEMPS 10 TO 15 DEGREES BELOW NORMAL REGION-
WIDE. ON THU LARGE SCALE FLOW BECOMES SOUTHWEST AND MODEL X-SECS
INDICATE MID LEVEL MOISTURE STREAMING INTO THE REGION...ESPECIALLY
IN THE AFTN. THE GFS AND CANADIAN ARE MOST AGGRESSIVE IN BRINGING
PRECIP IN PRIOR TO 00Z ALONG AND WEST OF THE DE RIVER...AND THIS
TIMING IS REFLECTED IN THE FCSR. MAX TEMPS WILL GENERALLY BE
5 TO 10 DEGREES BELOW NORMAL.

THU NIGHT THRU FRIDAY NIGHT...
LOW PRESSURE MOVES THRU THE SAINT LAWRENCE VALLEY WITH GOOD MODEL
AGREEMENT ON THE STRONGEST DYNAMICS JUST TO THE NORTH AND WEST...
AND THUS RESULTANT QPF BULLSEYE. ATTM...MODEL QPF IS GENERALLY A
TRACE OVER THE DELMARVA TO 0.2 INCHES OVER THE FAR NORTHWEST. THE
GREATEST UNCERTAINTY IS IN MODEL THERMAL PROFILES AND THUS PTYPE.
THIS DOES NOT APPEAR TO BE A COLD AIR DAMMING SITUATION WITH HIGH
PRES OFFSHORE AND THE ABSENCE OF AN INVERSION. NEVERTHELESS...LOW
PRES WELL NORTHWEST WILL LEAD TO BOUNDARY LAYER WINDS INSUFFICIENT
FOR WARM AIR ADVECTION. MODEL SOUNDINGS INDICATE A RAIN/SNOW EVENT
WITH CURRENT PROFILES CONFINING RAIN TO SOUTHEAST NJ...DE...AND MD
WHERE MODEL QPF IS LIGHTEST. EXPECTING SNOW-LIQUID RATIOS RANGING
FROM 5:1 TO 10:1 WHICH WOULD GIVE ACCUMULATIONS UP TO 1 INCH INVOF
I-95 TO 3 INCHES OVER THE NORTHWEST...BUT THIS IS PRELIMINARY...
STAY TUNED. PRECIP ENDS EARLY FRI WITH STRONG COLD AIR ADVECTION
AS LOW PRESSURE REDEVELOPS EAST OF NEW ENG...AS TEMPS FALL THRU
THE DAY AFTER MORNING MAXS. THERE IS ALSO THE POTENTIAL FOR SNOW
SQUALLS...PARTICULARLY OVER THE POCONOS...WITH A COLD FRONTAL
PASSAGE FRI AFTN. MODEL SOUNDINGS SHOW MIXING TO 850 HPA
WITH POTENTIAL FOR WIND GUSTS AROUND 30 KNOTS. THE COMBINATION
OF BLUSTERY WINDS AND BELOW NORMAL TEMPERATURES ON FRIDAY NIGHT
WILL LEAD TO LOW WIND CHILLS...THEREFORE...A WIND CHILL ADVISORY
MAY EVENTUALLY BE NEEDED.

SAT AND SUN...
MID-LEVEL CYCLONIC FLOW OVER THE REGION ON SAT GRADUALLY GIVES WAY
TO BRIEF RIDGING ON SUN. ON SAT THE COLUMN WILL DRY OUT...ASIDE
FOR POSSIBILITY OF STRATOCUMULUS BENEATH A MODELED SUBSIDENCE
INVERSION...WITH ONE LAST BRISK DAY IN NORTHWEST FLOW BEHIND
DEPARTING LOW. MID LEVEL FLOW ON SUNDAY BECOMES SOUTHWEST...AND
THE COLUMN WILL GRADUALLY MOISTEN IN ADVANCE OF STORM SYSTEM TO
THE SOUTHWEST. TEMPS EXPECTED TO BE 10 TO 15 DEGREES BELOW NORMAL.

SUNDAY NIGHT THRU TUESDAY...
COMPLICATED FORECAST AS LOW PRESSURE TRAVERSES THE APPALACHIANS
LATE SUNDAY INTO EARLY MONDAY. STRONG MID-LEVEL VORT MAX APPROACHES
THE COAST WITH DUAL JET SETUP FAVORING REDEVELOPMENT INVOF MID ATL
OR NEW ENGLAND. ATTM...THERMAL PROFILES GENERALLY FAVOR SNOW WITH
RAIN MIXING IN CLOSER TO THE COAST...BUT THIS IS HIGHLY UNCERTAIN.
REDEVELOPMENT COULD LEAD TO COLDER AIR BEING DRAWN IN...WHICH
WOULD BRING SNOW FURTHER SOUTH ALONG THE COAST. ANY WINTER WX
WOULD BE EXACERBATED BY COLD ANTECEDENT CONDITIONS...MAKING
SURFACES MORE PRONE TO ICING.

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...

THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

CONDITIONS HAVE GRADUALLY IMPROVED TO VFR AND SKIES WILL TRANSITION
TO BROKEN AND SCATTERED THROUGHOUT THE EVENING. NORTHWEST WIND GUSTS
AROUND 20 KNOTS WILL CONTINUE AT ALL TAF SITES. FOR TONIGHT THERE IS
POTENTIAL FOR SOME SCATTERED LOW CLOUDS AROUND 2,000 FEET TO FORM.
HOWEVER, WITH CONTINUED NORTHWEST WINDS OVER 10 KNOTS THERE IS
LITTLE TO MODERATE CONFIDENCE THIS WILL OCCUR.

WEDNESDAY WILL BE A VFR DAY WITH NORTHWEST GUSTS AGAIN AROUND 20
KNOTS. SOME HIGHER GUSTS ARE POSSIBLE IN THE AFTERNOON. GUSTS
WILL AGAIN DECREASE AFTER SUNSET.

OUTLOOK...

WEDNESDAY NIGHT...PRIMARILY VFR.

THURSDAY INTO FRIDAY MORNING...PRIMARILY VFR FOR MUCH OF THU. LIGHT
SNOW IS EXPECTED TO OVERSPREAD THE AREA FROM WEST TO EAST THU NIGHT
BUT MAY REACH ABE/RDG BY LATE AFTERNOON. MVFR/IFR POSSIBLE WITH THE
SNOW. HIGHEST CONFIDENCE IS AT NORTHERN TERMINALS.

FRIDAY AFTERNOON...VFR WITH NW WINDS GUSTING AROUND 30 KT.

FRI NIGHT...VFR WITH GUSTY NW WINDS EXPECTED TO CONTINUE.

SATURDAY...VFR.

SUNDAY...LIGHT SNOW IS EXPECTED TO OVERSPREAD THE AREA FROM WEST TO
EAST DURING THE DAY...LOW CONFIDENCE ON TIMING. MVFR/IFR POSSIBLE
WITH THE SNOW.

&&

.MARINE...
GALE WIND GUSTS HAVE TAPERED OFF IN CONJUNCTION WITH THE DEPARTING
LOW PRESSURE SYSTEM. HOWEVER, ON THE BACKSIDE OF THE LOW PRESSURE
STRONG NORTHWEST WINDS WITH SCA GUSTS WILL LIKELY CONTINUE TILL
AROUND 18Z WEDNESDAY IN ALL MARINE ZONES, WITH SOME SCATTERED SCA
GUSTS THROUGH 23Z. WAVE HEIGHTS WILL GRADUALLY DECREASE BY WEDNESDAY
AFTERNOON TO AROUND FIVE FEET. WE HAVE CANCELLED THE REMAINDER OF
THE GALE WARNING AND REPLACED WITH A SCA THROUGH 23Z WEDNESDAY,
ENDING EARLIER ON THE BAY.

OUTLOOK...

WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...NO MARINE HEADLINES
ARE ANTICIPATED. SOME FREEZING SPRAY POSSIBLE WEDNESDAY NIGHT.

FRIDAY...NEAR GALE-FORCE NW GUSTS BEHIND DEPARTING LOW PRESSURE.

FRIDAY NIGHT...POSSIBLE LEFTOVER NW GALE FORCE GUSTS. FREEZING
SPRAY LIKELY.

SATURDAY...SCA CONDITIONS POSSIBLE. FREEZING SPRAY POSSIBLE...
ESPECIALLY EARLY.

SUNDAY...CONDITIONS ARE EXPECTED TO REMAIN BELOW SCA THRESHOLDS.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING UNTIL 6 PM EST THIS EVENING FOR ANZ430-431-
     450>455.

&&

$$
SYNOPSIS...FRANCK
NEAR TERM...MIKETTA
SHORT TERM...MIKETTA
LONG TERM...FRANCK
AVIATION...FRANCK/GAINES
MARINE...FRANCK/GAINES






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