Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 020026 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 726 PM EST SUN MAR 1 2015 .SYNOPSIS... WEAK LOW PRESSURE AND A DISTURBANCE AT UPPER LEVELS OF THE ATMOSPHERE WILL TRACK NORTHEAST UP THE OHIO VALLEY AND CROSS PENNSYLVANIA THIS EVENING. THIS PAIR OF WEATHER FEATURES WILL BRING PERIODS OF LIGHT TO BRIEFLY MODERATE SNOW...THEN SOME MIXED PRECIPITATION TO SOUTH-CENTRAL PA AND THE LOWER SUSQ VALLEY INTO THIS EVENING. HIGH PRESSURE WILL BRING FAIR AND COLD CONDITIONS TO REGION MONDAY AND MONDAY NIGHT. A STRONGER AREA OF LOW PRESSURE WILL LIKELY TRACK WEST OF PENNSYLVANIA LATE TUESDAY AND EARLY WEDNESDAY...BRINGING MAINLY RAIN TO THE AREA. COLDER TEMPERATURES WILL FOLLOW FOR THE LATER PART OF THE WEEK. && .NEAR TERM /UNTIL 11 PM THIS EVENING/... DID ADJUST THE AREA OF FREEZING RAIN SOME...TO FIT IN WITH THE CURRENT OBS. EARLIER DISCUSSION BELOW. BRIGHT BANDING AND ELEVATED CCS SHOWING THE PRECIP TRANSITION ZONE WELL AS IT TRANSLATES NORTH OF THE MD BORDER INTO THE SOUTH CENTRAL MOUNTAINS AND FAR LOWER SUSQ RIVER VALLEY. 3" OF NEW SNOW O.G. NEAR GREENCASTLE FROM A TRUSTED WEATHER SPOTTER AND NOW FREEZING RAIN OCCURRING AT 27F. SLEET HAD BRIEFLY MIXED IN EARLIER ACROSS SOUTHERN YORK. A GENERAL 2-4" IS EXPECTED SOUTH OF INTERSTATE 80 AND EAST OF ROUTE 99...WITH THE ADDITIONAL CHANGEOVER TO ICE ACROSS SOUTHERN PORTIONS OF THE SOUTH CENTRAL MOUNTAINS AND LOWER SUSQ RIVER VALLEY ADDING ANOTHER .1 TO .15" OF ICE ON TOP IN THOSE AREAS. OVERALL SCENARIO PLAYING OUT WITH WITH PERIODS OF SNOW (OF VARYING INTENSITY) CONTINUING TO INCREASE IN AREAL COVERAGE THIS AFTERNOON FROM SOUTHWEST TO NORTHEAST. STRONG VERTICAL SHEAR EVIDENT ACROSS THE REGION WITH 150+ KT 250 MB JET SLICING ENE ACROSS THE NORTHERN OHIO VALLEY AND EASTERN GLAKS. BOUNDARY LAYER CONVERGENCE AND FORCING IS BEST ACROSS SOUTHERN PA THIS AFTERNOON AND EVENING...IN VICINITY OF 850 MB JET FEATURES...FIRST OF WHICH HAS SPAWNED A FEW HOURS OF MODERATE TO LOCALLY HEAVY PRECIP RATES FROM NORTHERN MARYLAND INTO MY SOUTHEAST COUNTIES. THIS IS PROGGED TO EXIT EASTWARD BY LATE AFTERNOON/EVENING BEFORE A MORE BROAD AREA OF BOUNDARY LAYER CONVERGENCE DEVELOPS AS THE UPPER TROF NEARS. 12Z RAP HANDLED THE ONGOING CHANGEOVER QUITE WELL FOR AREAS ALONG THE MD BORDER...AND EXPECT MDT TO BE CHANGING OVER IN THE NEXT HOUR OR TWO...STARTING WITH A MIXTURE OF SLEET AND THEN MAINLY LIGHT FREEZING RAIN AFTERWARD WITH AROUND 0.10 INCH QPF. WILL CONTINUE TO RIDE WITH A BLEND OF CURRENT AND UPCOMING HIGH RES GUIDANCE FOR ICE ACROSS OUR SRN ZONES...UNLESS WE SEE REASON TO SIGNIFICANTLY DEVIATE. WE WILL CONTINUE TO HOLD OFF ON ANY UPGRADES TO WINTER STORM/ICE STORM WARNINGS AT THIS TIME...AS AMOUNTS ARE EXPECTED TO REMAIN IN THE .1 TO .15" RANGE OVERALL...WITH SOME APPROACHING .20" ON TOP OF THE 2-4" OF SNOW ACCUM. ELSEWHERE...GOOD CONSISTENCY OF PAST SEVERAL MODEL/ENSEMBLE CYCLES CONTINUES THIS AFTERNOON WITH RESPECT TO PTYPE...WITH BULK OF THIS WINTRY EVENT FALLING AS SNOW TO THE NORTH OF THE RT22/322 CORRIDOR IN CENTRAL PENN. AMOUNTS AND DISTRIBUTION HAVE BEEN TRICKY GIVEN THE LACK OF FORCING FARTHER NORTH...BUT IN GENERAL IT APPEARS THAT 2-4" WILL BE COMMON FOR MOST...WHILE BETTER UPSLOPE AND MOISTURE TRANSPORT INTO THE WEST CENTRAL MOUNTAINS AND LAUREL HIGHLANDS PRODUCE MAX AMOUNTS THERE...GENERALLY UP TO 6" BUT WE COULD SEE SOME SPOT AMOUNTS COME IN HIGHER. TEMPS WILL WILL CONTINUE TO SLOWLY RISE TO A LATE DAY HIGH IN THE UPPER 20S ACROSS THE CENTRAL AND NORTHERN MTNS...AND LOWER TO MID 30S ACROSS THE LOWER SUSQ VALLEY AND LAUREL HIGHLANDS RESPECTIVELY. WINDS WILL BE SOUTH TO SW AT 5-8 KTS IN MOST PLACES THROUGH TODAY. && .SHORT TERM /11 PM THIS EVENING THROUGH MONDAY NIGHT/... PRECIP LOOKS TO TAPER OFF IN ALL AREAS DURING THE LATE EVENING THROUGH VERY EARLY MORNING HOURS OF MONDAY. LOW TEMPS TONIGHT /UNDER PLENTY OF LINGERING AND MORE SHALLOW...WARMER LOWER CLOUDS/ WILL RANGE FROM NEAR 20 DEG IN THE NORTH TO 30F IN ACROSS THE SOUTH. BLUSTERY AND COLDER CONDITIONS WILL MAKE A RETURN ON MONDAY AS SYSTEM NUMBER ONE SLIDES OFF TO OUR EAST. OTHER THAN THE USUAL POST FRONTAL SNOWS SHOWERS...FAVORING WESTERN HIGHER ELEVATIONS...CONDITIONS WILL BE GRADUALLY IMPROVING OVERALL THROUGHOUT THE DAY. DID NOT MAKE ANY LARGE CHANGES TO MONDAY. && .LONG TERM /TUESDAY THROUGH SUNDAY/... HIGH PRESSURE AND ITS FAIR WEATHER AND LIGHT WIND WILL BE SHORT LIVED MONDAY NIGHT INTO TUESDAY WHEN THE NEXT IN THE SERIES OF STORM SYSTEMS IS SLATED TO ENTER THE LOCAL WEATHER SCENE. THIS ONE PROMISES MORE OF A MESSY OUTCOME AS IT SHOULD TRACK WELL TO OUR NW...MEANING WARM AIR EVENTUALLY INVADING THE REGION...WITH A SNOW TO SLEET/FREEZING RAIN AND EVEN RAIN SCENARIO. SNOW AMOUNTS DO NOT LOOK TO BE THE BIGGEST PART OF THE MIDWEEK STORM AS WE ARE PROGGED TO WARM ALOFT RATHER QUICKLY. WITH A DEEP SNOW PACK AND A LOT OF COLD AIR TO DISPLACE...WE WILL LIKELY SEE A PERIOD OF ICING BEFORE WARM AIR EVENTUALLY CHANGES EVERYTHING TO RAIN TUESDAY NIGHT INTO WEDNESDAY. MAIN CHANGE WAS TO ADJUST POPS SOME TUE INTO TUE NIGHT. THINK MAIN TYPE OF PCPN WILL BE RAIN TUE NIGHT INTO WED. DID PUT SMALL AMTS OF .01 ICE ACROSS THE AREA...GIVEN THAT OBJECT TEMPS WILL STILL LIKELY BE COLD. TEMPERATURES TUE NIGHT MAY DROP A LITTLE...BEFORE COMING BACK UP LATE. RAIN SHOULD TAPER OFF TO SCATTERED SHOWERS WITH THE PASSAGE OF THE TRAILING COLD FRONT EARLY WEDNESDAY. FOR WED...TOOK SNOW SHOWERS OUT OF THE NW. TIGHT THICKNESS PATTERN ACROSS THE AREA...SUPPORT A LARGE TEMPERATURE GRADIENT FROM NW PA TO SE PA. THERE COULD BE A FEW SHOW SHOWERS ACROSS THE FAR NW...BUT IT LOOKS LIKE MAINLY NW OF OUR AREA. LEFT POPS UP...THINK FRONT WILL BE SLOW TO MOVE OUT. A TREND TOWARD COLDER WEATHER AGAIN LATER IN THE WEEK...GIVEN SPLIT FLOW. PUSH OF ARCTIC AIR WILL BRING TEMPS AND POPS BACK WELL BELOW NORMAL FOR LATE THURSDAY INTO FRIDAY. THE ONLY GOOD THING SEEMS TO BE EACH ARCTIC SHOT IS A LITTLE LESS POTENT THAN THE LAST AS WE LEAVE THE RECORD COLD OF FEBRUARY BEHIND. && .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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ONE LAST BAND OF HEAVIER SNOW ASSOCIATED WITH COLD FRONT TRACKING THROUGH CENTRAL PENNSYLVANIA FROM KIPT TO KUNV TO KAOO AT 00Z. WHAT REMAINS OF THE LIGHT PRECIPITATION OVER THE SOUTHEAST SECTIONS CONTINUES TO BE IN THE FORM OF LIGHT FZRA OR PL. KJST HAS CREPT INTO THE WARM SECTOR...AND IS NOW 34 DEGREES WITH PLAIN RAIN. EXPECT PRECIPITATION TO LIGHTEN CONSIDERABLY FROM WEST TO EAST OVER THE NEXT 3 TO 6 HOURS. THIS WILL INTRODUCE A SLOW IMPROVEMENT IN FLYING CONDITIONS OVERNIGHT...BUT MANY LOCATIONS WILL REMAIN IFR TO MVFR OVERNIGHT. CONDITIONS WILL SLOWLY IMPROVE ON MONDAY...BUT EXPECT RESTRICTIONS TO LINGER IN THE WESTERN AND NORTHERN HIGHER TERRAIN ON COLD NORTHWEST WINDS AND TYPICAL OROGRAPHIC SNOW SHOWERS. BRIEF RESPITE LATER MONDAY INTO EARLY TUESDAY...BEFORE THE NEXT SYSTEM PUSHES ANOTHER ROUND OF PRECIPITATION AND REDUCED FLYING CONDITIONS INTO THE AREA LATER TUESDAY AND WEDNESDAY. OUTLOOK... TUE...VFR AM. MIXED PRECIP WITH CIG/VIS REDUCTIONS POSSIBLE LATE. WED...CIG/VIS REDUCTIONS CONTINUE IN WINTRY MIX/RAIN. THU...SLOWLY IMPROVING CONDITIONS...LINGERING MVFR NW AND SE. FRI...MAINLY VFR.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 2 AM EST MONDAY FOR PAZ019-027- 028-037-041-042-045-046-049>053-056>059-063>066. WINTER WEATHER ADVISORY UNTIL 7 AM EST MONDAY FOR PAZ004>006- 010>012-017-018-024-033. WINTER WEATHER ADVISORY UNTIL 11 PM EST THIS EVENING FOR PAZ025-026-034>036. && $$ SYNOPSIS...DEVOIR/LAMBERT/MARTIN NEAR TERM...DEVOIR/LAMBERT/MARTIN SHORT TERM...DEVOIR/LAMBERT/MARTIN LONG TERM...LA CORTE/LAMBERT/MARTIN AVIATION...JUNG

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