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Area Forecast Discussion
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000
FXUS61 KPHI 200855
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
355 AM EST SAT DEC 20 2014

.SYNOPSIS...
HIGH PRESSURE CENTERED OVER SOUTHWESTERN QUEBEC THIS MORNING WILL
DRIFT EASTWARD AND IT SHOULD REACH ATLANTIC CANADA ON MONDAY. WEAK
LOW PRESSURE IS FORECAST TO DEVELOP OFF THE CAROLINA COAST ON
MONDAY BEFORE MOVING SLOWLY NORTHEASTWARD AND DISSIPATING. STRONG
LOW PRESSURE IS EXPECTED TO LIFT NORTHWARD FROM THE LOWER
MISSISSIPPI RIVER VALLEY AND ACROSS THE GREAT LAKES DURING THE MID
WEEK PERIOD. THE LOW IS ANTICIPATED TO PULL A WARM FRONT THROUGH
OUR REGION ON WEDNESDAY, FOLLOWED BY A COLD FRONT ON WEDNESDAY
NIGHT. HIGH PRESSURE IS EXPECTED TO FOLLOW FROM THE SOUTHWEST FOR
THURSDAY AND FRIDAY. ANOTHER COLD FRONT IS FORECAST TO APPROACH
FROM THE WEST AND IT MAY ARRIVE ON SATURDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS EASTERN CANADA AND
NORTHERN NEW ENGLAND TODAY, WITH THE MID-ATLANTIC BEING ON THE
SOUTHERN FRINGE. THIS WILL KEEP A DRY, LIGHT NORTHERLY FLOW ACROSS
THE AREA. WITH PW VALUES BETWEEN ONE-QUARTER AND ONE-THIRD OF AN
INCH, NO PRECIPITATION IS FORECAST. HOWEVER, THERE WILL REMAIN
MOISTURE CAUGHT UP UNDERNEATH THE INVERSION WHICH SHOULD KEEP SOME
CLOUD COVER ACROSS THE AREA. EVEN IF THE LOWER LEVEL CLOUDS
SCATTER OUT DURING THE DAY, WE SHOULD SEE AN INCREASE IN HIGH
LEVEL CLOUDS AS A SHORT WAVE/VORTICITY MAX SLIDES ACROSS THE AREA.
THE NORTHERLY WIND, ALONG WITH ANY CLOUD COVER SHOULD PREVENT
TEMPERATURES FROM WARMING SIGNIFICANTLY TODAY, SO WE USED A BLEND
OF MAV/MET MOS AND MOSGUIDE WHICH WERE IN PRETTY GOOD AGREEMENT.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
NOT MUCH OF A CHANGE TO THE FORECAST TONIGHT FROM THE DAY TIME.
HIGH PRESSURE, CENTERED ACROSS NORTHERN NEW ENGLAND AND EASTERN
CANADA REMAINS IN CONTROL OF THE WEATHER. WITH CONTINUING LOW PW
VALUES, NO PRECIPITATION IS EXPECTED. CLOUD COVER SHOULD REMAIN
ACROSS THE AREA, ESPECIALLY AS A SHORT WAVE/VORTICITY MAX SLIDES
TOWARD THE AREA OVERNIGHT.

OVERNIGHT LOWS WERE A BLEND OF MAV/MET MOS AND MOSGUIDE WHICH
WERE IN PRETTY GOOD AGREEMENT.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
A MID LEVEL SHORT WAVE THAT WAS LOCATED OVER WESTERN IOWA AND
VICINITY EARLY THIS MORNING WILL PROGRESS EASTWARD AND IT SHOULD
PASS OVER OUR REGION EARLY ON SUNDAY MORNING. WHILE WE ARE
ANTICIPATING SOME CLOUDS WITH THE SYSTEM THERE SHOULD NOT BE
ENOUGH MOISTURE TO PRODUCE ANY PRECIPITATION.

SURFACE HIGH PRESSURE IS FORECAST TO BE LOCATED OVER SOUTHERN
QUEBEC ON SUNDAY MORNING. THE CENTER OF THE HIGH SHOULD DRIFT
EASTWARD REACHING ATLANTIC CANADA ON MONDAY AND MONDAY NIGHT. A
RIDGE AXIS IS EXPECTED TO NOSE SOUTHWESTWARD ALONG THE LEE OF THE
APPALACHIANS AT THAT TIME WITH AN INVERTED TROUGH DEVELOPING OFF
THE COAST. WEAK LOW PRESSURE IS ANTICIPATED TO DEVELOP ON THE
TROUGH OFF THE CAROLINA COAST ON MONDAY. THE FEATURE IS FORECAST
TO REMAIN WEAK AS IT DRIFTS NORTHEASTWARD REACHING THE WATERS OFF
THE DELMARVA BEFORE DISSIPATING ON TUESDAY.

AREAS OF LIGHT PRECIPITATION ARE EXPECTED TO SPREAD SLOWLY
NORTHWARD INTO OUR REGION ON MONDAY AND THEY SHOULD REMAIN HERE
FOR MONDAY NIGHT AND TUESDAY. THE OVERALL TREND WILL BE TOWARD
WARMING TEMPERATURES. AS A RESULT, MOST OF THE PRECIPITATION IS
ANTICIPATED TO BE IN THE FORM OF RAIN. HOWEVER, POCKETS OF BELOW
FREEZING TEMPERATURES MAY LINGER IN THE POCONOS ON MONDAY NIGHT
INTO EARLY TUESDAY MORNING SO WE HAVE MENTIONED A CHANCE OF
FREEZING RAIN THERE.

OUR MAIN WEATHER FEATURE FOR THE COMING WEEK IS THE DEEP MID
LEVEL TROUGH THAT IS FORECAST TO DIG OVER THE MIDDLE PART OF THE
COUNTRY ON MONDAY AND TUESDAY. THE TROUGH IS EXPECTED TO LIFT
NORTHEASTWARD AND ITS AXIS SHOULD PASS OVERHEAD EARLY ON THURSDAY.

SURFACE LOW PRESSURE IS ANTICIPATED TO DEVELOP OVER THE LOWER
MISSISSIPPI RIVER VALLEY ON TUESDAY IN RESPONSE TO THE TROUGH. THE
LOW IS FORECAST TO STRENGTHEN AS IT MOVES ACROSS THE GREAT LAKES
ON WEDNESDAY AND WEDNESDAY NIGHT. THE SYSTEM SHOULD HAVE AN
OPPORTUNITY TO TAP INTO GULF MOISTURE AND IT WILL BRING THE
POTENTIAL FOR SOME MODERATE TO HEAVY RAINFALL TO OUR REGION FROM
WEDNESDAY INTO EARLY WEDNESDAY NIGHT.

THE LOW IS EXPECTED TO PULL A WARM FRONT THROUGH OUR REGION ON
WEDNESDAY WITH TEMPERATURES FORECAST TO RISE INTO THE 50S AT MOST
LOCATIONS. SOME 60 DEGREE READINGS ARE POSSIBLE ON THE DELMARVA
AND PERHAPS IN FAR SOUTHERN NEW JERSEY. CONDITIONS MAY BECOME
QUITE BREEZY IN THE WARM SECTOR WHERE THE ATMOSPHERE SHOULD MIX
RATHER EFFICIENTLY. A STRONG COLD FRONT IS FORECAST TO FOLLOW ON
WEDNESDAY NIGHT WITH TEMPERATURES DROPPING BACK INTO THE 30S BY
DAYBREAK ON THURSDAY. THE PROBABILITY OF PRECIPITATION DECREASES
RAPIDLY ON WEDNESDAY NIGHT AS DRY AIR IS EXPECTED TO BUILD INTO
OUR REGION FROM THE SOUTHWEST.

RIDGING IS FORECAST TO DEVELOP AT THE SURFACE AND ALOFT FOR
THURSDAY INTO FRIDAY WITH MAINLY DRY WEATHER AND SEASONABLE
TEMPERATURES ANTICIPATED.

A MID LEVEL SHORT WAVE MAY APPROACH FROM THE WEST ON SATURDAY
ALONG WITH AN ASSOCIATED SURFACE COLD FRONT. THE GUIDANCE DIFFERS
A BIT ON THE TIMING OF THE FEATURE AT THIS POINT AS WELL ON THE
AMOUNT OF MOISTURE ASSOCIATED WITH THE SYSTEM.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

MOST OF THE TAF SITES ARE NOW MVFR, EXCEPT PHL/ILG/MIV, ALTHOUGH
THEY SHOULD BE THERE SHORTLY. THE MVFR CIGS WILL CONTINUE ACROSS
THE TAF SITES THROUGH THIS MORNING AS MOISTURE REMAINS TRAPPED
UNDERNEATH THE INVERSION. CLOUDS MAY SCATTER OUT DURING THE DAY
WITH HIGHER LEVEL CLOUDS OVERHEAD, LEADING TO VFR CONDITIONS FOR
THE REMAINDER OF THE PERIOD. IF THE CLOUDS DO NOT BEGIN TO SCATTER
OUT BY MIDDAY, IT'S POSSIBLE WE COULD SEE AN EXTENDED PERIOD OF
MVFR CIGS THROUGH THE DAY INTO TONIGHT.

NORTHERLY WINDS WILL BE LIGHT, GENERALLY AROUND 5-10 KNOTS OR
LESS THROUGH THE DAY. SOME NORTHWEST TO WEST WINDS ARE POSSIBLE
EARLY, BUT SHOULD BECOME MORE NORTHERLY DURING THE DAY. EVERYONE
IS EXPECTED TO BECOME LIGHT AND VARIABLE/CALM LATER THIS AFTERNOON
INTO THE EVENING/OVERNIGHT.

OUTLOOK...
SUNDAY AND SUNDAY NIGHT...MAINLY VFR.

MONDAY...MAINLY VFR WITH A CHANCE OF LIGHT RAIN SPREADING
NORTHWARD INTO OUR REGION.

MONDAY NIGHT AND TUESDAY...CONDITIONS POSSIBLY LOWERING INTO THE
MVFR CATEGORY WITH A CHANCE OF LIGHT RAIN.

TUESDAY NIGHT...MVFR AND IFR CONDITIONS ANTICIPATED WITH RAIN
LIKELY.

WEDNESDAY...MVFR AND IFR CONDITIONS WITH RAIN LIKELY. THE RAIN
MAY BE HEAVY AT TIMES. A GUSTY SOUTH WIND MAY DEVELOP, ESPECIALLY
IN THE AFTERNOON.

&&

.MARINE...
SUB-SMALL CRAFT ADVISORY CONDITIONS WILL REMAIN TODAY INTO
TONIGHT AS HIGH PRESSURE FROM THE NORTH WILL AFFECT THE WATERS.

OUTLOOK...
SUNDAY THROUGH MONDAY NIGHT...NO MARINE HEADLINES ARE
ANTICIPATED.

TUESDAY AND TUESDAY NIGHT...WAVE HEIGHTS ON OUR OCEAN WATERS MAY
BUILD TO 5 TO 6 FEET IN A DEVELOPING ONSHORE FLOW.

WEDNESDAY...SOUTHERLY WIND GUSTS IN EXCESS OF 25 KNOTS ARE
EXPECTED. WAVE HEIGHTS ON OUR OCEAN WATERS MAY BUILD TO 6 TO 9
FEET IN A STRONG SOUTHERLY FLOW.

&&

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

&&

$$

SYNOPSIS...IOVINO
NEAR TERM...ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...IOVINO
AVIATION...IOVINO/ROBERTSON
MARINE...IOVINO/ROBERTSON






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