Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 190612 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 112 AM EST FRI DEC 19 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 THIS 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 THIS MORNING THROUGH 6 PM SATURDAY/... 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 /SATURDAY 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 /06Z FRIDAY THROUGH TUESDAY/...
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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 THE OVERNIGHT. 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 OCCURRING OR WILL OCCUR BETWEEN 06Z 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 FRI 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. TUE...LOW CIGS WITH RAIN LIKELY.
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&& .CTP WATCHES/WARNINGS/ADVISORIES...
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WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR PAZ004>006-010-011-037.
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&& $$ SYNOPSIS...LA CORTE NEAR TERM...LA CORTE SHORT TERM...DEVOIR LONG TERM...STEINBUGL AVIATION...CERU/RXR

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