Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 291814 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 214 PM EDT MON SEP 29 2014 .SYNOPSIS... A WEAK COLD FRONT AND AN UPPER LEVEL DISTURBANCE WILL MOVE OUT OF THE GREAT LAKES AND BRING AN INCREASE IN CLOUDS ALONG WITH SOME SHOWERS OR THUNDERSTORMS TUESDAY INTO WEDNESDAY. A STRONGER COLD FRONT WILL PUSH EAST INTO THE COMMONWEALTH LATE FRIDAY NIGHT OR SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... SATELLITE SHOWS A LARGE SHIELD OF MAINLY MID AND HIGH CLOUDS STREAMING NE AHEAD OF A WEAK SHORTWAVE LIFTING OUT OF THE OHIO VALLEY. WHILE RADAR SHOWS SOME RETURNS...ESPECIALLY OVER SERN SXNS...SURFACE OBSERVATIONS SHOW NO RAIN REACHING THE GROUND ANYWHERE NEARBY. TEMPS ARE STILL ON TRACK TO TOP 70 IN ALL AREAS...REACHING NEAR 80 OVER THE SOUTHEAST DESPITE THE CLOUDCOVER. LATEST SHORT RANGE OPERATIONAL GUIDANCE INDICATES THE OVERNIGHT...WHILE PROBABLY SEEING CLOUDS INCREASE...SHOULD STAY DRY IN MOST AREAS. I DID PUT MORE AREAS OF FOG AFTER MIDNIGHT...BUT CONFIDENCE IS LOWER THAN RECENT NIGHTS DUE TO THE CLOUDS THAT SHOULD BE MOVING IN FROM THE APPROACHING SYSTEM. && .SHORT TERM /TUESDAY/... A COMPACT UPPER SHORTWAVE/LOW WILL DROP OUT OF THE LOWER GR LAKES TUESDAY. DECREASING STABILITY UNDER THE COLD POOL ALOFT WILL HELP SUPPORT THE DEVELOPMENT OF SCATTERED SHOWERS AND THUNDERSTORMS. ENSEMBLES AND OPERATIONAL GUIDANCE INDICATE THAT CAPE WILL BE MODEST...BUT FORECAST TOTAL-TOTALS IN EXCESS OF 50 ARE USUALLY A GOOD INDICATOR FOR THE POTENTIAL OF SOME LOW TOPPED CONVECTION. BASIN AVERAGE RAINFALL IS EXPECTED TO BE LIGHT...ON THE ORDER OF 0.10 OF AN INCH OR LESS...BUT AMOUNTS COULD BE SLIGHTLY HEAVIER...0.15 TO 0.25 OF AN INCH...ACROSS THE FAR NW TUESDAY AFTERNOON AND EVENING. MAX TEMPS TUESDAY ARE EXPECTED TO BE JUST A FEW DEG COOLER AND IN THE LOWER TO MID 70S. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... EXPANSIVE UPPER RIDGE OVER THE EASTERN HALF OF THE CONUS WILL REMAIN IN CONTROL TO A LARGE DEGREE THROUGH MUCH OF THE PERIOD. SEVERAL SHORTWAVES IN THE NRN STREAM WILL SLOWLY BREAK DOWN THE RIDGE...WITH A LARGE SCALE UPPER TROF FORECAST TO MOVE INTO THE EASTERN PART OF THE COUNTRY BY NEXT WEEKEND. MODELS CONTINUE IN FAIR AGREEMENT AS BOTH THE EC AND THE GFS BRING A SHORT WAVE TROUGH THROUGH THE REGION MONDAY NIGHT INTO WEDNESDAY....WITH THE EC STRONGER WITH THE MID LEVEL LOW. A WEAK FRONT SHOULD BE ASSOCIATED WITH THIS TROUGH...HOWEVER LACK OF MOISTURE SHOULD ONLY ALLOW FOR POTENTIAL FOR LIGHT PRECIPITATION THROUGH THE NW MTNS LATE MONDAY NIGHT/TUESDAY MORNING DUE TO LAKE MOISTURE AND UPSLOPE FLOW. LATEST...00Z U.S. AND EC MODEL GUIDANCE /AND GEFS/ STILL SHOW A GREAT DEAL OF SPREAD IN THEIR SOLUTIONS WITH RESPECT TO THE LOCATION AND STRENGTH OF THE AFOREMENTIONED UPPER TROUGH THAT WILL BECOME CARVED OUT ACROSS THE ERN U.S DURING THE TUES-THUR TIME- FRAME. MOST SOLUTIONS WARRANT AT LEAST A LOW CHC FOR SHOWERS EACH OF THOSE 3 DAYS...WITH THE GREATEST CHC FOR SHOWERS BECOMING CONFINED OVER THE EASTERN HALF OF THE CWA TUESDAY NIGHT THROUGH THURSDAY AS AN ANOMALOUS EASTERN LLVL FLOW DEVELOPS BETWEEN 1030 MB SFC HIGH PRESSURE OVER QUEBEC...AND A RELATIVELY WEAK 1008-1010MB LOW NEAR THE CAROLINA OR DELMARVA COAST. TRIMMED TEMPS BY A FEW DEG F TUESDAY THROUGH THURSDAY. IT APPEARS LIKELY THAT THE INCREASING EASTERLY FLOW AT LLVLS WILL BRING INCREASING CLOUDS AND WITH SLIGHTLY COOLER DAYS AND MILDER NIGHTS. EVEN MORE UNCERTAINTY IN FURTHER REACHES OF EXTENDED FORECAST. RIDGING SLIPS BACK IN FOR LATE WEEK AS A DECENT WAVE SLIDES SE FROM CANADIAN ROCKIES IN WAKE OF WEAKENING UPPER LOW /THAT LIFTED INTO CENTRAL CANADA FROM CALIFORNIA/. AT THIS TIME...EC WEAKER AND MORE PROGRESSIVE WHILE GFS DEEPER AND SLOWER. APPEARS TO BE SOME CONSENSUS THAT PCPN ARRIVES INTO WRN PA ON FRIDAY...AND SIG PCPN WITH THE SFC FRONT EXITS THE STATE EARLY ON SAT. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... THE REGION IS EXPERIENCING SOME LAYERED MID-HIGH CLOUDS DRIFTING ACROSS THE SKY AHEAD OF A WEAK UPPER DISTURBANCE. EXPECT WIDESPREAD VFR CONDITIONS TO CONTINUE INTO TONIGHT. REDUCED CONDITIONS WITH LOCALIZED FOG MAY AGAIN BE A CONCERN LATER TONIGHT. IF THE UPSTREAM CLOUDS FROM THE APPROACHING GR LAKES FRONTAL SYSTEM MOVE IN QUICKER THAN EXPECTED...THIS WOULD PUT A DAMPER ON THE FOG AND ASSURE VFR CONDITIONS CONTINUE INTO THE DAY TUESDAY. TUE-WED...AN UPPER TROUGH/LOW DROPPING OUT OF THE GR LAKES INTO THE LOCAL AREA WILL BRING SCT RAIN SHOWERS AND EVEN SOME THUNDERSTORMS. LOW CIGS PROBABLE AT NIGHT. OUTLOOK /THU THROUGH SAT/... THU...LOW CIGS COULD LINGER MUCH OF THE DAY AS HIGH PRESSURE TO THE EAST PROVIDES AN EAST-SOUTHEAST MARITIME FLOW. FRI...SHOWERS AND THUNDERSTORMS PSBL ASSOC WITH GUSTY FROPA. SAT...BREEZY WITH IMPROVING CONDITIONS. SHOWERS AND LOCAL MVFR POSSIBLE OVER NWRN AREAS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE NEAR TERM...LA CORTE SHORT TERM...LA CORTE LONG TERM...LAMBERT/GARTNER AVIATION...LA CORTE

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