Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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552
FXUS61 KPHI 111714
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1214 PM EST THU FEB 11 2016

.SYNOPSIS...
HIGH PRESSURE WILL BUILD EASTWARD INTO THE REGION TODAY AND THEN
MOVE THROUGH THE REGION TONIGHT. AN ARCTIC COLD FRONTAL BOUNDARY
WILL THEN MOVE THROUGH THE AREA FRIDAY NIGHT. BY SUNDAY, ANOTHER
AREA OF HIGH PRESSURE WILL BUILD SOUTHWARD INTO THE REGION AS LOW
PRESSURE FORMS ACROSS THE SOUTHERN UNITED STATES BY MONDAY. THIS
AREA OF LOW PRESSURE WILL THEN TRACK UP THE EAST COAST TUESDAY INTO
WEDNESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
1140 AM ESTF: HAVE UPDATED THE AFTN PACKAGE AND ONLY CHANGES
FORTHCOMING WITH THE STANDARD 1230PM MIGHT BE A SLIGHT UPWARD
ADJUSTMENT OF SNOW AMTS IN THE POCONOS AND SUSSEX COUNTY NJ. WE
HAVE WIDESPREAD 1/2 INCH IN THE GRIDS FOR THE REGION I-78 NORTH
BUT THE LEGACY READS FOR THE MOST PART, LITTLE OR NO.

"HEAVY" WORDING NOW RESERVED FOR I-78 REGION NORTH THIS AFTN.

UPDATED SNOW MAP POSTED.

COLD... MINOR ADJUSTMENTS TO THE MID SHIFT TEMPS AND DEWS. WINDS
WERE BOOSTED ABOUT 5 MPH ON THE LAND....GUSTS 25-35 MPH.

THE SCIENCE BEHIND THE SNOW SHOWERS...EXTREME AND MOIST BOUNDARY
LAYER LAPSE RATES ASSOCIATED WITH THE COLD POOL UP THROUGH MID
LVLS--- ROUGHLY 500MB. BOTH THE BGM WINDEX TOOL AND THE BTV SNOWSQL
PARM TOOLS SHOW HUGE VALUES BOTH THIS MORNING, THIS AFTERNOON AND
PROBABLY AGAIN SATURDAY WITH REAL DEAL TRUE ARCTIC PLUNGE.

TONIGHT...SNOW SHOWERS TRAIL OUT TO SEA AND DISSIPATE THIS EVENING
AS THE SFC HEATING WANES AND THE COLD POOL ALOFT WARMS A BIT. SKIES
CLEAR MOST OF THE AREA AND WINDS DIMINISH AS A RIDGE OF HIGH PRESSURE
POKES FROM THE SOUTHWEST IN WITH SOME RADIATIONAL COOLING ON TODAYS
FRESHENED SNOW COVER. WE WILL RUN A 50 50 BLEND OF 12Z/11 GFS/NAM
MOS BUT WILL PROBABLY ALLOW FOR COOLER THAN THIS FCST BY SEVERAL
DEGREES OVER E PA AND NW NJ RADIATORS. SHOULD GET CLOSE TO 3 ABOVE
IN PARTS OF E PA RADIATIORS PER GFS 2M TEMPS. WESTERLY WINDS
BECOME LIGHT LATE.

&&

.SHORT TERM /FRIDAY/...
SUNNY, THEN INCREASING CLOUDS...MAINLY HIGH CLOUDS. WINDS TURN SW
AND THE UNSTABLE AIR OVER THE STILL OPEN WATERS OF THE BAYS MAY
YIELD SOME BAY EFFECT FLURRIES LATE IN THE DAY. OTHERWISE, SNOW
SHOWERS IN THE WAA PATTERN IN PA COULD DEVELOP FLURRIES OR SNOW
SHOWERS IN THE POCONOS AFTER 5 PM.  SW WIND.

50 50 BLENDED 12Z/11 GFS/NAM MOS GUIDANCE.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
OUR UPDATED BRIEFING PACKAGE AT MIDDAY WILL INCLUDE MORE INFORMATION
ON THE UPCOMING DANGEROUS COLD, INCLUDING A POSSIBLE WIND CHILL
WATCH FOR SAT NIGHT WHICH IS ALREADY A HIGH CONFIDENCE LIKELIHOOD.

THE EXTENDED WILL FEATURE BOTH THE PROSPECTS FOR THE COLDEST AIR
OF THE SEASON CENTERED ON SUNDAY MORNING AND A STRENGTHENING LOW
PRESSURE SYSTEM TRACKING UP THE EAST COAST EARLY NEXT WEEK.

FRIDAY AND SATURDAY: HIGH PRESSURE WILL MOVE THROUGH THE REGION ON
FRIDAY. THIS HIGH PRESSURE SYSTEM WILL GIVE WAY TO ANOTHER ARCTIC
COLD FRONT FRIDAY NIGHT. THE COLD FRONT SHOULD PROVIDE ENOUGH
LIFT AND MOISTURE FOR SOME SCATTERED SNOW SHOWERS TO DEVELOP.
THESE MAY PRODUCE SOME LIGHT ACCUMULATIONS OF UNDER AN INCH.

BEHIND THE FRONT, IT WILL BE A VERY COLD AND WINDY PERIOD WITH
SOME ADDITIONAL SNOW SHOWERS AND/OR FLURRIES IN ASSOCIATION WITH
THE NW FLOW OFF OF THE EASTERN GREAT LAKES. THE FAVORED REGIONS TO
SEE SNOW SHOWERS ARE IN THE HIGH TERRAIN AREAS OF EASTERN PA AND
NW NJ. BUFKIT ANALYSIS YIELDS THE POTENTIAL FOR 30-40 MPH GUSTS
SATURDAY AFTERNOON ACROSS THE REGION WITH THE GFS BEING THE MOST
AGGRESSIVE WITH THE GUST POTENTIAL. THE STRONG CAA WILL NOT ALLOW
TEMPERATURES TO RISE MUCH DURING THE DAY.

SATURDAY NIGHT THROUGH SUNDAY NIGHT: ANOTHER POTENT AREA OF ARCTIC
HIGH PRESSURE WILL BUILD INTO THE REGION WITH THE COLDEST SHOT OF
AIR OF THE SEASON SO FAR. MODELING HAS BEEN HOLDING STEADY ON THE
IDEA THAT 850 MB TEMPERATURES LOOK TO DIVE BELOW -25C. WILL
NUDGE TEMPERATURES A COUPLE OF DEGREES COOLER THAN MOST ENSEMBLE
GUIDANCE THROUGH THE WEEKEND DUE TO THE DEGREE OF THE COLD AIR
BEING MODELED. STRONG NORTHWEST WIND GUSTS, THOUGH NOT AS STRONG
AS ON SATURDAY WILL CONTINUE IN THE WAKE OF THE DEPARTING SYSTEM.
THE COLD AND WIND WILL RESULT IN WIND CHILLS FROM -10 TO -30 BELOW
ZERO SATURDAY NIGHT AND SUNDAY MORNING. PLEASE TO MAKE SURE TO
PREPARE FOR THE COLD WEATHER THAT IS COMING. PREPARATIONS INCLUDE
CHECKING PIPES AND MAKING SURE YOUR VEHICLE IS IN GOOD WORKING
CONDITION. LOW TEMPERATURES SUNDAY MORNING WILL LIKELY NEAR OR
BELOW ZERO AS WELL. PLEASE REFER TO THE CLIMATE SECTION ON RECORD
POTENTIAL.

PRESIDENTS DAY THROUGH TUESDAY NIGHT: HIGH PRESSURE WILL GRADUALLY
MOVE EAST OF THE REGION AND WILL GIVE WAY TO A STORM SYSTEM THAT IS
CURRENTLY MODELED TO FORM ACROSS THE SOUTHERN UNITED STATES AND
INTENSIFY AS IT MOVES UP THE EAST COAST. THE 00Z 2/11 OPERATIONAL
MODELS HAVE NARROWED THE GOAL POSTS OF POSSIBLE TRACKS FROM
EARLIER MODEL RUNS. THIS ALSO MATCHES OR IS JUST EAST OF THE 12Z
2/10 ECMWF ENSEMBLE MEAN TRACK. THIS TRACK GOES FROM SOUTH CENTRAL
AL/GA NORTHEAST TO THE CAROLINA COASTLINE THEN DUE NORTH UP THE
EAST COAST INTO SOUTHERN NEW ENGLAND. TWO MAIN FEATURES ARE
PRESENT TO TRACK WITH REGARDS TO MODELS OR RESPECTIVE ENSEMBLES
CHANGING THE FORECAST TRACK OF THIS SYSTEM IN FUTURE RUNS. THIS
FIRST IS A LEADING SHORTWAVE WHICH MOVES INTO THE THE OHIO VALLEY
ON MONDAY AND THE SECOND IS THE DEGREE OF MID- LEVEL HEIGHT RISES
THAT OCCUR AHEAD OF THE STORM SYSTEM. A STRONGER SHORTWAVE WOULD
TEND TO PUSH THE OVERALL TROUGH WITH THIS STORM FURTHER EAST.
WHILE A WEAKER SHORTWAVE WOULD ALLOW FOR HIGHER MID- LEVEL HEIGHT
RISES LEADING TO A FURTHER WEST TRACK OF THE LOW. RIGHT NOW THE
FAVORED TRACK WOULD RESULT IN SNOW CHANGING TO RAIN ACROSS MOST OF
THE REGION WITH THE HIGHEST CHANCES FOR PRECIPITATION MONDAY NIGHT
AND TUESDAY. IT WILL LIKELY BE WINDY AS WELL WITH THE
STRENGTHENING LOW PRESSURE SYSTEM TRACKING NEAR THE REGION.

WEDNESDAY: THE REGION SHOULD GRADUALLY BEGIN TO CLEAR OUT AS
ANOTHER HIGH PRESSURE SYSTEM BUILDS EASTWARD TOWARD THE REGION.
SOME UNCERTAINTY THOUGH AS 2/11 00Z ECMWF BRINGS ANOTHER SYSTEM
INTO THE REGION BY THIS PERIOD.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

THIS AFTERNOON...VFR SCT-BKN AOA 4000 FT. BRIEF IFR CONDS IN SNOW
SHOWERS DEVELOP KTTN/KRDG AND KABE DURING MID AFTN AND MAY SLIP
SOUTH TO VCNTY KPHL AND KACY AROUND 22Z. WEST WIND GUSTY AROUND 30
KT, ISOLATED 35 KT.

SNOW SHOWERS ARE ASSOCIATED WITH EXTREMELY LARGE AND MOIST LOW
LVL LAPSE RATES. ALSO AIDING MAY BE THE LAKE ERIE MOISTURE PLUME
(RECENTLY LARGELY NON ICE COVERED).

WEST WIND GUSTS INCREASING TO 30 KT BY 16Z. ISOLATED 35 KT POSSIBLE.

TONIGHT...VFR SCT-BKN CLOUDS AOA 4000 FT DURING THE EVENING BECOMING
CLEAR. ANY LEFTOVER SNOW SHOWERS SHOULD END BY 02Z. GUSTY WNW WINDS
20-30 KT SLOWLY DIMINISHING DURING THE NIGHT.

FRIDAY...VFR. CIRRUS CIGS ARRIVE AND THEN LOWER DURING THE AFTN.
SW WIND.

OUTLOOK...

FRIDAY NIGHT AND SATURDAY: MAINLY VFR, POSSIBLE MVFR RESTRICTIONS
IN SCATTERED SNOW SHOWERS. NORTHWEST WINDS INCREASING SATURDAY
FROM 15-25 KNOTS WITH GUSTS UP TO 40 KNOTS SATURDAY AFTERNOON.

SATURDAY NIGHT AND SUNDAY...VFR CONDITIONS EXPECTED. NORTHWEST WINDS
10 TO 25 KNOTS.

MONDAY...VFR CONDITIONS FOR MOST OF THE DAY THEN BECOMING MVFR AND
IFR BY EVENING WITH RAIN AND SNOW.

&&

.MARINE...
GALES IN PROGRESS AND GLW CONTINUES AS POSTED. AN SCA WILL BE NEEDED
FOR MUCH IF NOT ALL OF THE OVER NIGHT HOURS ONCE THE GALES SUBSIDE.

LIGHT FREEZING SPRAY IS OCCURRING AND CONTINUES TO BE EXPECTED ON
THE BAY AS WELL AS THE NEAR COASTAL WATERS THROUGH TONIGHT.

FRIDAY NO HEADLINE! A GOOD DAY TO FINISH UP ANY MARINE RELATED ACTIVITY.

OUTLOOK...

OUR MID AFTERNOON MARINE PRODUCTS WILL HEADLINE A NEW HIGH CONFIDENCE
GALE WATCH FOR THE PERIOD ROUGHLY 4 AM SATURDAY THROUGH 8 AM SUNDAY.

SO WHILE, SEAS AND WINDS WILL START OUT FAIRLY LIGHT ON FRIDAY.
HOWEVER, A QUICK RAMP UP IS EXPECTED AFTER THE PASSAGE OF AN
ARCTIC COLD FRONTAL BOUNDARY FRIDAY NIGHT. NORTHWEST WINDS WILL
INCREASE AND REACH GALE FORCE BY SATURDAY AND CONTINUE GALE FORCE
THROUGH SATURDAY NIGHT. CONFIDENCE FOR GALES ON SATURDAY IS
VERY HIGH. SEAS WILL RISE TO BETWEEN 5 AND 7 FEET FOR A PERIOD AS
WELL ON SATURDAY. SEAS AND WINDS ARE EXPECTED TO DECREASE ON
SUNDAY. WAVE HEIGHTS WILL LIKELY START INCREASING AGAIN BY MONDAY
NIGHT IN RESPONSE TO A DEVELOPING LOW PRESSURE SYSTEM TO OUR
SOUTH.

&&

.CLIMATE...
NEAR RECORD COLD IS EXPECTED FOR PORTIONS OF OUR AREA SUNDAY
MORNING AND BY FAR THE COLDEST AIR OF THE SEASON SO FAR.

ANTICIPATING TEMPS THROUGHOUT OUR FORECAST AREA WITHIN SEVERAL
DEGREES OF ZERO (WIND IS THE EQUALIZER) ANYTIME FROM MIDNIGHT
THROUGH 8 AM SUNDAY EXCEPT COLDER KMPO (NEAR -12F). THIS HAS BEEN
ADVERTISED BY THE GFS/ECMWF 2M TEMPS CYCLICALLY SINCE AT LEAST THE
00Z/7 OPERATIONAL CYCLES. THEREFORE, BEST CHANCE FOR RECORD
EQUALING OR EXCEEDING FOR VALENTINES DAY THE 14TH WOULD BE KABE,
KTTN, KPHL AND KMPO.

SNOW COVER MAY HELP A BIT I-95 NORTHWESTWARD...AND WE`LL SEE
WHERE WE ARE WITH SNOW COVER BY THURSDAY EVENING. NEW DUSTINGS
APPEAR ON THE WAY THROUGH FRIDAY NIGHT.

PLEASE NOTE... GUIDANCE IN PART IS BEING CLIMO BIASED HIGHER THAN
WHAT THE ONCOMING GFS/ECMWF LITERAL AIRMASS AND 2M TEMPS ARE INDICATING
FOR SUNDAY MORNING. TEMPS SUNDAY MORNING IN THE URBAN AREAS SHOULD
BE ABOUT 25 COLDER THAN NORMAL. THAT MEANS GUIDANCE TEMPS FOR PHL
OF 5 AND 6 DEGREES APPEAR TOO WARM...ESPECIALLY WITH A NORMAL
PHILADELPHIA LOW ON SUNDAY OF 28.

HAVE SEEN THE 12Z/11 2M TEMPS FOR PHL...1 ABOVE RANGING DOWN TO
-11 AT KMPO AND AM LIKING THOSE VALUES AS WITHIN 2F OF THE
UPCOMING REALITY.

RECORD LOW MAX`S CAN ONLY OCCUR FOR THIS EVENT ON SUNDAY THE
14TH, IF THEN.  THOSE HAVE BEEN ADDED RECENTLY BELOW.

SITE 2015-16 COLDEST SO FAR RECORD LOW FEB. 14TH ----RER LOW MAX
---------------------- --------------------

ABE             8                         -1 IN 1979     14-1979

ACY             10                        -6 IN 1979     13-1979

PHL             12                        +2 IN 1979     14-1979

ILG             12                        -4 IN 1979     13-1979

RDG             10                        -4 IN 1983

TTN              9                         0 IN 1916

GED             13                        -7 IN 1979

MPO             -1                       -12 IN 1970

SO, THIS WILL BE WIND DRIVEN COLD WITH MANY AREAS EXPERIENCING
WIND CHILL VALUES OF 15 TO 25 BELOW ZERO...POSSIBLY 30 BELOW IN
THE HILLS AND MOUNTAINS OF NORTHWEST NEW JERSEY AND NORTHEAST
PENNSYLVANIA.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...GALE WARNING UNTIL 1 AM EST FRIDAY FOR ANZ450>455.
     GALE WARNING UNTIL 11 PM EST THIS EVENING FOR ANZ430-431.

&&

$$
SYNOPSIS...FRANCK
NEAR TERM...DRAG 1214
SHORT TERM...DRAG 1214
LONG TERM...GAINES
AVIATION...DRAG/GAINES 1214
MARINE...DRAG/GAINES 1214
CLIMATE...1214



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