Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 190455
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
1155 PM EST THU DEC 18 2014

.SYNOPSIS...
COLD NORTHWEST WINDS WILL KEEP FLURRIES AND SCATTERED LIGHT SNOW
SHOWERS OVER THE NORTH AND WEST INTO FRIDAY MORNING. HIGH
PRESSURE WILL SLIDE DOWN FROM THE UPPER GREAT LAKES AND PROVIDE A
GENERALLY FAIR PERIOD FOR MOST OF THE WEEKEND.

AN UNSETTLED PATTERN WILL SET UP IN THE FIRST PART OF THE NEW
WEEK. A WEAK LOW PRESSURE AREA COULD AFFECT THE AREA MONDAY. THEN
A MORE SIGNIFICANT STORM IS EXPECTED MOVE INTO THE REGION FOR
CHRISTMAS EVE...FOLLOWED BY STRONG WINDS AND SCATTERED SNOW
SHOWERS FOR CHRISTMAS DAY.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AFTER COORDINATING WITH SURROUNDING OFFICES..HAVE OPTED FOR AN
ADVISORY FOR FREEZING DRIZZLE OVER MY NORTHERN COUNTIES. STILL NOT
EXPECTING MUCH...BUT TRAVEL COULD BE IMPACTED SO WE HAVE THE
HEADLINE OUT THROUGH 7 AM.

NO OTHER CHANGES MADE TO THE NEAR TERM FORECAST.

HAVE TINKERED WITH THE NEAR TERM POPS AS MAINLY LIGHT SNOW
SHOWERS OR FLURRIES SEEM THE MOST LIKELY OUTCOME THIS EVENING AND
OVERNIGHT FOR MUCH OF MY WESTERN AND NORTHERN FORECAST AREA. WEST
FACING SLOPES OF THE WEST CENTRAL MOUNTAINS AND LAUREL HIGHLANDS
MAY SEE A LOCALIZED COATING OF SNOW LATE TONIGHT INTO FRI MORNING.

OTHERWISE EXPECT WIDESPREAD STRATUS TO PERSIST ACROSS MOST OF
CENTRAL PA. THE SOUTHEAST WILL LIKELY SEE SOME DISSIPATION BY
FRIDAY MORNING. SURFACE HIGH CENTERED OVER THE NORTHERN GREAT
LAKES AND EASTERN QUEBEC WILL KEEP NORTH/NORTHWEST BOUNDARY LAYER
FLOW GOING THROUGH FRI MORNING...TRANSLATING TO SFC WINDS IN THE 7
TO 11 MPH RANGE.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
UPPER FORCING SLIDES EAST OF THE REGION EARLY FRIDAY MORNING...
WITH EXPANSIVE SURFACE HIGH PRESSURE BUILDING OVER THE AREA IN THE
AFTERNOON. THUS...THE AMOUNT/COVERAGE OF THE SNOW SHOWERS AND
FLURRIES SHOULD DIMINISH COMPLETELY ON FRIDAY. MINS WILL STAY A
LITTLE MILDER THAN CLIMO WITH CLOUDS AROUND. MAXES ON FRIDAY VERY
SIMILAR TO TODAY...WITH 30S FOR THE MOUNTAINS AND NEAR 40 IN THE
LOW LANDS WITH THE HELP OF SOME DOWNSLOPE WARMING.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL SHIFT SLOWLY EASTWARD FROM THE GREAT LAKES
INTO NORTHERN NEW ENGLAND BY 12Z MONDAY. RESIDUAL LOW LEVEL
MOISTURE ALONG WITH NRN STREAM SHORTWAVE ENERGY ATTEMPTING TO
UNDERCUT AN UPPER RIDGE/HIGH HEIGHTS MIGRATING OVER SOUTHEASTERN
CANADA SHOULD LIMIT SUN INTERVALS---HOWEVER THE SUN SHOULD AT
LEAST MAKE A BRIEF APPEARANCE THIS WEEKEND. SPLIT FLOW REGIME
ACROSS THE LOWER 48 WILL TRANSITION TO A HIGHLY AMPLIFIED PATTERN
BY EARLY NEXT WEEK ACROSS THE LOWER 48...WITH A DEEP NEGATIVELY
TILTED TROUGH EVOLVING OVER THE EASTERN 1/3RD OF THE CONUS.

THE MODELS SEEM TO BE FORMING A CONSENSUS ON THE PESKY LOW
THAT REFUSES TO BE WELL FORECAST...LIFTING IT SLOWLY FROM FL
PANHANDLE NNEWD JUST OFF THE EAST COAST SUN-MON ALONG A LOW LEVEL
BAROCLINIC ZONE THAT MAY NOT BUDGE PAST THE GULF STREAM AS THE
FLOW ALOFT TURNS SOUTHWESTERLY/PARALLEL TO THE COASTAL FRONT.
INCREASED POPS FOR MONDAY OVER THE SE BASED ON MULTI-MODEL/WPC
BLEND. COMPLEX SFC PATTERN WITH SOME HINTS AT LOW LEVEL CAD ALONG
WITH WAA ALOFT VIA SLY FLOW COULD MAKE FOR A MESSY MIXED PTYPE
TRANSITION.

AN INTENSE TRIPLE POINT SYSTEM DEVELOPING ON DEC 23-24 WILL
LIKELY STEAL THE HEADLINES GIVEN ITS TIMING AND LARGE PORTION OF
REAL ESTATE THAT WILL BE AFFECTED. WHILE THE DETAILS REMAIN
UNCLEAR AT THIS POINT...TEMPERATURES SHOULD BE WARM ENOUGH TO
SUPPORT RAIN ON THE FRONT SIDE OF THE SYSTEM BEFORE BRISK WNW
WINDS DRIVE STRONG CAA EAST OF THE APPALACHIANS. THE TIMING OF THE
COLD/OCCLUDED FRONT WILL BE KEY FOR PRECIPITATION TRANSITION FROM
RAIN TO SNOW SHOWERS. AS THE SYSTEM SPINS UP INTO EASTERN
CANADA...THE STRONG CAA CIRCULATING THROUGH THE GREAT LAKES AND OH
VLY SHOULD LEAD TO LAKE EFFECT/UPSLOPE/WRAP AROUND SNOW SHOWERS
OVER THE WESTERN ALLEGHENIES BY CHRISTMAS DAY. A PERIOD OF STRONG
GUSTY WINDS ARE HIGHLY PROBABLE AS THE DYNAMIC SYSTEM INTENSIFIES
SHIFTING NWWD FROM NEW ENGLAND INTO ONTARIO/QUEBEC.

THE TAKE HOME MESSAGE IS THAT A VOLATILE PERIOD OF WEATHER WILL
IMPACT THE AREA THROUGH CHRISTMAS DAY WITH POTENTIAL WIND...RAIN
AND SNOW IMPACTS ALL ON THE TABLE. STAY TUNED.

&&

.AVIATION /05Z FRIDAY THROUGH TUESDAY/... LOW LVL MOISTURE
TRAPPED BENEATH INVERSION AND NORTHWEST FLOW OVER THE EASTERN
GLAKS WILL KEEP STRATO CU IN PLACE ACROSS MOST OF CENTRAL PA
THROUGH TONIGHT. LATEST MDL SOUNDINGS POINT TOWARD PREDOMINANTLY
IFR CIGS/VSBYS AT KBFD AND KJST. THE MODELS SHOW SOME VARIATION
BUT MVFR CIGS AT ALL OTHER TAF SITES EITHER ARE CURRENTLY
OCCURRINGOR WILL OCCUR BETWEEN 06Z TO 12Z. IPT SHOULD DEVELOP
BETWEEN 09Z TO 12Z.

A TROUGH OF LOW PRESSURE WILL PUSH THRU THE REGION OVERNIGHT...PERHAPS
PRODUCING A PERIOD OF STEADIER LGT SNOW AT KBFD AND KJST BTWN 06Z-
12Z FRIDAY WITH VSBYS IN THE 2 TO 4SM RANGE. SKIES WILL STEADILY
IMPROVE AS THE DAY CONTINUES WITH VFR CIGS BY 15Z AT ALL TAF
SITES. EXPECT REDUCING CONDITIONS TOMORROW EVENING AT ONLY BFD
AND POSSIBLY JST.


OUTLOOK...

FRI...EARLY AM -SHSN/REDUCED VSBYS POSS AT KJST.

SAT-SUN...NO SIG WX EXPECTED.

MON...LOW CIGS WITH LGT RAIN/SNOW POSSIBLE.

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 7 AM EST FRIDAY FOR PAZ004>006-
010-011-037.

&&

$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...DEVOIR
LONG TERM...STEINBUGL
AVIATION...DEVOIR/CERU


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