Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 240124 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 924 PM EDT TUE SEP 23 2014 .SYNOPSIS... HIGH PRESSURE CENTERED OVER WESTERN PENNSYLVANIA WILL DRIFT TO THE MAINE COAST BY WEDNESDAY AFTERNOON. A LOW PRESSURE SYSTEM WILL TRACK UP THE MID ATLANTIC COAST WEDNESDAY AND THURSDAY. DEEP AND MODERATELY STRONG EASTERLY FLOW BETWEEN THESE TWO WEATHER FEATURES WILL TRANSPORT ABUNDANT MOISTURE IN FROM THE ATLANTIC...LEADING TO PERIODS OF RAIN WEDNESDAY NIGHT INTO THURSDAY ACROSS THE EASTERN HALF OF THE STATE. AN ANOMALOUS UPPER RIDGE WILL MIGRATE EASTWARD FROM THE GREAT LAKES THIS WEEKEND AND BRING A STRING OF SUNNY...WARM DAYS. && .NEAR TERM /UNTIL 9 AM WEDNESDAY MORNING/... CIRRUS SHOULD INCREASE A LITTLE IN THE SE...BUT MUCH OF THE AREA WILL REMAIN CLEAR OVERNIGHT. LOWS TEMPS TONIGHT WILL BE MAINLY IN THE LOWER TO MID 40S. A FEW SPOTS ACROSS THE NORTH WILL LIKELY DIP INTO THE U30S. THUS...THE USUAL VALLEY LOCATIONS WILL HAVE FOG AROUND SUNRISE...WHICH SHOULD BURN AWAY BY 9 OR 10 AM. VERY PATCHY FROST IS POSSIBLE IN A FEW SPOTS...BUT NOT ENOUGH TO WARRANT A FROST ADVY ANYWHERE SPECIFIC. && .SHORT TERM /9 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... A DECENT AMOUNT OF SUNSHINE IS EXPECTED EARLY IN THE DAY. CIRRUS WILL GRADUALLY SPREAD NORTH-NORTHWEST DURING THE MIDDAY AND AFTERNOON HOURS...WITH A THICK ALTOSTRATUS DECK EXPECTED ACROSS THE LOWER SUSQ VALLEY /AND POSSIBLY ACROSS THE SCENT MTNS AS WELL/ BY 22Z WED. LIGHT RAIN WILL BE KNOCKING ON THE DOORSTEP OF THE LOWER SUSQ VALLEY LATE WEDNESDAY AFTERNOON AS THE NOSE OF A HIGHLY ANOMALOUS ESE 850 MB JET /-3 TO -4 ST DEVIATIONS/...AND PWATS IN EXCESS OF 1.5 INCHES BECOMES AIMED RIGHT INTO THAT REGION. POPS WILL BE ESSENTIALLY ZERO ACROSS PRACTICALLY ALL OF THE CWA THROUGH 00Z THURSDAY...BUT INCREASE TO 20-30 PERCENT TO THE SE OF A KTHV AND KLNS LINE. TEMPS WED SHOULD BE FAIRLY UNIFORM IN THE U60S TO ARND 70F DUE TO THE THICKEST CLOUDS ARRIVING OVR THE NORMALLY WARMER SOUTHERN COUNTIES. SHOULD CLOUDS THICKEN UP FASTER THAN ANTICIPATED ACROSS THE SOUTH...DAYTIME TEMPS MAY HAVE TO BE TRIMMED BY A FEW TO SEVERAL DEG F. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... THE MODELS CONTINUE TO SHOW INCONSISTENCY IN A RUN BY RUN BASIS AS THE NAM/EC/GEFS/SREF AND GFS NOW BACK PRECIP EASTWARD...THOUGH STILL WESTWARD ENOUGH TO AFFECT CENTRAL PA. GFS REMAINS THE MOST CONSISTENT OF THEM AS IT CONTINUES THE HEAVIEST PRECIP IN THE DELMARVA REGION. MADE CHANGES TO THE WED NITE/THURSDAY FCST...DUE TO THE CHANGE IN TRACK OF THE COASTAL LOW ACROSS THE DELMARVA. THIS SYSTEM SHOULD BRING MOIST EAST TO SOUTHEASTERLY FLOW AND ACCOMPANYING RAINSHOWERS TO AT LEAST THE SE COUNTIES ON THURSDAY. THE EC BRINGS THE PRECIP NORTHWARD THROUGH CENTRAL PA BEFORE IT SHIFTS NORTHEASTWARD AND HEADS UP THE COAST. A TIGHT PRESSURE GRADIENT BETWEEN THE HIGH EAST OF NEW ENG AND SFC LOW RIDING UP THE EAST COAST SHOULD AMPLIFY THE ANOMALOUS EASTERLY WINDS/PWATS IN THE 12Z GEFS...THOUGH THE HIGHEST PWATS SHOULD ONLY AFFECT SE PA WED NIGHT THROUGH THURSDAY MORNING. SOME ENSEMBLE AND OPERATIONAL RUNS INDICATE A SUBSTANTIAL RAINFALL OF OVER AN INCH IS POSSIBLE ACROSS PARTS OF SE PA. GIVEN THE VARIABILITY BETWEEN THE OUTPUTS HAVE QPFS IN THE 0.75 TO ONE INCH RANGE. HAVE INCREASED MIN TEMPS WED NIGHT AND LOWERED MAX TEMPS WED SIGNIFICANTLY DUE TO THE EXPECTED CLOUD COVER/RAIN. GENERAL AGREEMENT AMONG MED RANGE GUIDANCE THAT COASTAL LOW WILL EXIT THE MID ATLANTIC COAST THURSDAY NIGHT INTO FRIDAY...BRINGING A RETURN TO FAIR AND MILD WX. ANOMALOUS UPPER LVL RIDGE OVR THE GRT LKS IS THEN PROGGED TO SLIDE EAST INTO PA OVR THE WEEKEND...BRINGING THE AREA A PERIOD OF FAIR AND WARM WX THAT SHOULD LAST INTO EARLY NEXT WEEK. LG SCALE SUBSIDENCE BENEATH THIS SYSTEM SHOULD RESULT IN MCLEAR SKIES THRU THE WEEKEND. MID LEVEL TEMPERATURES IN THE GEFS AND ECMWF SHOULD SUPPORT HIGH TEMPS ARND 10F ABOVE NORMAL...WITH AFTN READINGS BTWN 75-80F OVR MUCH OF THE AREA THROUGH THE WEEKEND. ANOTHER LOW LOOKS TO BE APPROACHING THE REGION BY THE MIDDLE OF NEXT WEEK. DUE TO THE LARGE VARIATION IN TIMING HAVE ONLY CHANCE POPS TUESDAY INTO WEDNESDAY. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... NICE EARLY FALL EVENING WITH OUTSIDE WITH VFR CONDITIONS. INTERESTING RETURNS ON RADAR...COULD BE BIRDS. NOT EXPECTING A LOT OF FOG LATE TONIGHT. PERHAPS A LITTLE AT UNV AND AOO. LOW CIGS AND SOME FOG WILL BE POSSIBLE AT IPT. BASED ON GUIDANCE AND HOW THINGS WENT LAST NIGHT...ALONG WITH HAVING A FAIRLY DRY AIRMASS IN PLACE. FOR WED...A DEVELOPING...DEEP AND MDTLY STRONG EASTERLY FLOW /BETWEEN HIGH PRESSURE OVER THE NEW ENGLAND STATES...AND UPPER LEVEL LOW PRESSURE SYSTEM/SFC TROUGH OVER THE SE U.S./ WILL BRING CLOUDY SKIES AND A CHANCE FOR RAIN WED NIGHT AND THU...ESP ACROSS THE EASTERN HALF OF PENN. WIDESPREAD IFR TO MVFR CIGS /AND VSBYS IN THE SAME CATEGORY/ APPEAR LIKELY WED NIGHT THROUGH THURSDAY. OUTLOOK... WED...PATCHY FOG IN THE MORNING...OTHERWISE VFR. WED NIGHT AND THU...LOW CIGS AND AREAS OF -RA/DZ LIKELY. FRI-SUN...PATCHY 1/2SM FOG IN THE MORNING...OTHERWISE VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/LAMBERT NEAR TERM...DANGELO SHORT TERM...LAMBERT LONG TERM...FITZGERALD/CERU AVIATION...LAMBERT/MARTIN

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