Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 250954 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 554 AM EDT SAT APR 25 2015 .SYNOPSIS... HIGH PRESSURE RIDGING INTO PENNSYLVANIA FROM THE NORTH WILL HELP TO MAINTAIN DRY...COLD CONDITIONS EARLY TODAY...AS A THICKENING LAYER OF MID LEVEL CLOUDS SPREADS ACROSS THE COMMONWEALTH. LOW PRESSURE MOVING FROM THE MID MISSISSIPPI TO THE CAROLINA COAST WILL BRING THE RISK OF LIGHT RAIN ACROSS SOUTHERN PENNSYLVANIA LATER TODAY INTO SUNDAY...WITH THE POSSIBILITY OF SOME WET SNOW MIXING IN ACROSS THE HIGHEST ELEVATIONS OF THE LAUREL HIGHLANDS. A PERSISTENT UPPER LEVEL TROUGH OVER THE NORTHEASTERN UNITED STATES WILL FAVOR UNSEASONABLY COOL TEMPERATURES THROUGH THE END OF THIS MONTH. HEADING INTO THE FIRST FEW DAYS OF MAY ANOTHER SHARP TROUGH WILL FORM OVER THE EASTERN U.S. WITH A LIKELIHOOD OF BLUSTERY CONDITIONS WITH WELL BELOW NORMAL TEMPERATURES. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THICKENING ALTO CU AND ALTOSTRATUS DECK WILL ADVANCE EAST AND BLANKET MOST OR ALL OF OUR FCST AREA BY 12Z. FAVORABLE CONDITIONS FOR RADIATIONAL COOLING OF THE EARTH/S SURFACE OCCURRED FOR MUCH OF THE NIGHT ACROSS THE EASTERN HALF OF OUR CWA AND ALLOWED TEMPS TO TUMBLE...BUT FALL A FEW DEG F SHY OF RECORD LOWS AT KMDT AND KIPT. RECORD LOWS OF 30F AND 26F FOR THIS DATE AT KMDT AND KIPT ARE PROBABLY SAFE...BUT IT SHOULD BE CLOSE. A FREEZE WARNING REMAINS IN EFFECT THROUGH 13Z TODAY FOR THE COUNTIES ACROSS THE SOUTHEAST...WHERE GROWING SEASON HAS BEGUN. LATEST MESO OBS SHOW TEMPS IN THE UPPER 20S TO LOWER 30S IN THE RURAL VALLEY OF THE SCENT AND SE COUNTIES...WHILE THE LARGER METRO AREAS AND HILLTOP OB SITES SHOULD STAY GENERALLY BETWEEN 33 AND 35F. THIS MAY BE THE COLDEST MORNING UNTIL THE FALL...BUT EARLY MAY MAY HOLD A SURPRISE OR TWO BASED ON LATEST MEDIUM RANGE GUIDANCE WHICH SHOWS ANOTHER DEEP TROUGH FORMING OVER THE ERN U.S. LATE IN THE UPCOMING WEEK. MORE ON THAT IN THE LONG TERM SECTION BELOW. INITIAL ARM OF MID LEVEL WAA LIGHT RAIN /AHEAD OF A WEAKENING SHORTWAVE TROUGH/ WAS SPREADING SE ACROSS NERN OHIO AND FAR SWRN PENN. ENHANCED REFLECTIVITIES INVOF KPIT AND KCLE DUAL POL RADAR SITES INDICATE THE LOW MELTING LAYER OF ONLY 1000-2000 FT AGL. THIS STRATIFORM PRECIP AREA SHOULD CONTINUE TO DISSIPATE GRADUALLY AS IT ENCOUNTERS THE SLIGHTLY DRIER AIR AND NE EDGE OF STRONGER DEEP LAYER SUBSIDENCE BENEATH STRONG CONFLUENT FLOW ALOFT. MENTIONED A SLIGHT CHANCE FOR RAIN/SNOW SHOWERS ACROSS THE LAURELS EARLY TODAY. HIGH RES MODEL DATA APPEARS TO BE DISSIPATING THE PRECIP SHIELD QUICKER THAN WHAT WE/RE SEEING ON THE REGIONAL RADAR MOSAIC LOOP ATTM. WOULDN`T BE SURPRISED TO SEE A LIGHT COATING OF SNOW/PL ACROSS THE LAURELS THIS MORNING. ELSEWHERE...SKIES WILL BE MOSTLY CLOUDY TO CLOUDY WITH A FEW SPRINKLES /OR EARLY MORNING FLURRIES/ FALLING IN THE CORRIDOR BETWEEN RT22 AND INTERSTATE 80. AS A NEARLY EAST/WEST BELT OF -2 TO -3 SIGMA 850 MB EAST- NORTHEASTERLY WINDS SLIDES ACROSS FAR SOUTHERN PENN LATE TODAY AND TONIGHT...RAIN SHOULD BECOME STEADIER AND EVEN FALL MODERATELY HEAVY FOR BRIEF PERIODS. ELEVATIONS AOA 2400 MSL COULD SEE SOME WET SNOW MIXED IN AS 850 MB TEMPS TEETER ON 0C. HIGH TEMPS THIS AFTERNOON WILL VARY FROM NEAR 50F ACROSS THE LAUREL HIGHLANDS AND NRN MTNS...TO BETWEEN 55 AND 60 ELSEWHERE ACROSS CENTRAL AND SOUTHERN PENN. THESE FCST MAX TEMPS COULD BUST SLIGHTLY BY BEING A FEW TO SVRL DEG F TOO HIGH THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... WEAKENING SHORTWAVE AND ASSOCIATED ANOMALOUS EASTERLY 925-850 MB FLOW /APPROACHING FROM THE MISS VALLEY/ WILL LIKELY SPREAD A SHIELD OF STEADIER /MAINLY LIGHT/ RAIN INTO THE SW COUNTIES TOWARD EVENING. MODELS CONTINUE TO SHOW A SHARP MOISTURE GRADIENT ACROSS SOUTHERN/CENTRAL PA TONIGHT. WILL CARRY CAT POPS ACROSS SOMERSET CO THIS MORNING...BUT CARRY NO MENTION OF RAIN FROM I-80 NORTHWARD. ONLY A FEW SREF AND GEFS ENSEMBLE MEMBERS BRING MEASURABLE RAIN AS FAR NORTH AS KUNV. POPS DECREASE FROM NW TO SE LATE TONIGHT/EARLY SUNDAY...AS LG SCALE FORCING WANES BEHIND THE DEPARTING SHORTWAVE. HOWEVER...MDLS INDICATE LINGERING FGEN FORCING/DEEP LYR MOISTURE ALONG THE S TIER THRU SUN AM...SO OCNL LGT RAIN MAY LINGER THRU 16Z SUN DOWN THERE. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... WAVE SLIDING W-E THROUGH THE MID ATLANTIC REGION ALONG A FRONTAL BOUNDARY WILL KEEP MENTION OF PRIMARILY LIGHT RAIN IN THE FORECAST HEADING INTO SUNDAY FOR SOUTHERN PORTIONS OF CWA...WITH PRECIP SHIELD ALREADY RECEDING TOWARD THE SE BY 12Z SUN...AND EXITING THE REGION BY LATE MORNING. CONSENSUS OF MED RANGE MDLS SUPPORTS FAIR AND COOL WX FOR REMAINDER OF SUNDAY...AS WEAK SFC RIDGING BUILDS SOUTHWARD ACROSS PA. EARLY NEXT WEEK A SHOT OF COOL UNSETTLED WEATHER ARRIVES AS A BACK DOOR COLD FRONT IS NUDGED SOUTHWARD ACROSS PA FROM AN UPPER LOW OVR NEW ENG. COOL TEMPS ALOFT ASSOC WITH UPPER LOW WILL LIKELY LEAD TO A GOOD DEAL OF DAYTIME CLOUDINESS AND SCT SHRA /ESP OVR THE MTNS/ MONDAY AND TUESDAY. BY MIDWEEK...THIS LOW FINALLY LIFTS OUT FOR GOOD. BUT DIGGING TROUGH FROM UPPER MIDWEST WILL EXTEND INTO THE SOUTHEAST U.S. BY LATE WEEK...COMBINED WITH A SOUTHERN STREAM SHORTWAVE LIFTING OUT OF THE S PLAINS TOWARD THE E COAST WILL BRING POSSIBILITY OF A DEVELOPING STORM SLIDING NORTHEASTWARD OFF THE EASTERN SEABOARD. TRACK/STRENGTH STILL QUITE UNCERTAIN...BUT AT THIS TIME LOOKS LIKE WE/LL BE BETWEEN THAT LOW PRESSURE AREA AND A HIGH OVER OHIO VALLEY...LIKELY KEEPING CLOUDS AND SCT SHOWERS AROUND AS TEMPS COOL BACK DOWN A BIT. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... SFC HIGH PRES INITIALLY PROVIDING M/CLR SKIES AND LGT/VRB WINDS WILL YIELD TO LOW PRESSURE TRACKING EASTWARD FROM THE CENTRAL PLAINS TO JUST WEST OF THE CENTRAL APPALACHIANS BY TONIGHT BEFORE REDEVELOPING OFF THE NC COAST ON SUNDAY. CLOUDS WILL THICKEN AND GRADUALLY LOWER TODAY BUT EXPECT FLGT CATS TO GENERALLY REMAIN VFR. JST AND AOO HAVE THE HIGHEST RISK FOR A PERIOD OF LIGHT RAIN AND MVFR CIGS FROM THIS EVENING THROUGH TONIGHT. A LARGE UPPER LEVEL LOW OVER NEW ENGLAND WILL DOMINATE THE REGIONAL WEATHER PATTERN EARLY NEXT WEEK WITH SEVERAL SMALL SCALE DISTURBANCES ROTATING AROUND THE WESTERN PERIPHERY OF THE CIRCULATION CENTER. THE MODELS SEEM TO AGREE THAT ONE OF THESE DISTURBANCES WILL BRING A PERIOD OF SHOWERS TO THE AIRSPACE ON MONDAY. THE N-NW FLOW SHOULD FAVOR THE GREATEST RISK OF MVFR CIGS OVER THE NRN AND WRN AIRSPACE IN ZOB SECTOR. OUTLOOK... TUE...IMPROVING CONDITIONS WEST TO EAST. WED...GENERALLY VFR EARLY WITH CHC OF PM SHOWERS. && .CTP WATCHES/WARNINGS/ADVISORIES... FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR PAZ026>028-035- 036-049>052-056-057-059-063>066. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LAMBERT/ROSS LONG TERM...LAMBERT/RXR AVIATION...STEINBUGL

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