Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 041910 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 310 PM EDT MON MAY 4 2015 .SYNOPSIS...
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AFTER A SUNNY...BREEZY AND UNSEASONABLY WARM DAY...A SLOW MOVING COLD FRONT OVER THE LOWER GREAT LAKES THIS EVENING WILL SAG SOUTHEAST AND BECOME NEARLY STATIONARY OVER PENNSYLVANIA TUESDAY INTO WEDNESDAY. NUMEROUS...MAINLY AFTERNOON SHOWERS AND SCATTERED THUNDERSTORMS WILL OCCUR IN THE VICINITY OF THIS FRONTAL BOUNDARY TUESDAY. HIGH PRESSURE WILL RETURN FOR THE END OF THE WEEK. MUCH OF THIS WEEK WILL BE MUCH WARMER THAN NORMAL.
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&& .NEAR TERM /THROUGH TONIGHT/...
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THE DIFFERENCE IN PRESSURE BETWEEN AN AREA OF HIGH PRESSURE OFF THE EAST COAST AND A COLD FRONT HEADED OUR WAY FROM THE GREAT LAKES REGION WILL CREATE A GUSTY SOUTHWEST BREEZE AND AN UNSEASONABLY WARM AFTERNOON AND EVENING. WARMING ALOFT ACROSS CENTRAL AND WESTERN PENN HAS LEAD TO JUST A SPLECKLING OF FLAT/HIGH-BASED CU...AND HIS WILL BE THE CASE FOR THE REST OF THE AFTERNOON. THE EXCEPTION WILL BE ACROSS THE NW MTNS WHERE AN INCREASE IN LAYERED MID-LEVEL CLOUDS WILL OCCUR AFTER 20Z. STABILITY WILL BEGIN TO ERODE LATE IN THE DAY ACROSS THE FAR NW AS THE COLD FRONT PUSHES ACROSS THE EASTERN GR LAKES. HOWEVER...ONLY A FEW TO SVRL HUNDRED J/KG OF SFC BASED CAPE WILL BE ABLE TO BE GENERATED TO THE WEST OF RT 219 BRIEFLY LATE TODAY AND EARLY THIS EVENING..WELL AHEAD OF THE CFRONT. HIGH RES MODELS SUCH AS THE HRRR AND WRF ARW INDICATE THAT MOST OR ALL OF THE SHOWERS /CURRENTLY IN A BKN NARROW LINE ALONG AND JUST AHEAD OF THE CFRONT WILL BREAK APART AND HOLD OFF UNTIL WELL AFTER DARK ACROSS OUR CWA...EVEN ACROSS THE FAR NW ZONES. STILL THE LIKELIHOOD EXISTS FOR A FEW LATE NIGHT/PREDAWN SHOWERS ACROSS THE NRN HALF OF PENN AS A WEAK SHORT WAVE RIPPLES EAST OVER THE FRONTAL BOUNDARY. RAINFALL BETWEEN 00Z AND 12Z TUESDAY MAY BE UPWARDS OF 0.10-0.20 ACROSS THE NW MTNS...BUT LESS THAN 0.10 OF AN INCH ACROSS CENTRAL PENN...AND NOTHING ACROSS THE SE THIRD OF THE CWA. THE COLD FRONT WILL SETTLE SLOWLY SOUTH THROUGH THE STATE OVERNIGHT...CONTINUING THE THREAT FOR SHOWERS AND THUNDERSTORMS. A RIBBON OF ANOMALOUSLY HIGH PWATS WILL BECOME ORIENTED WEST- EAST ACROSS THE STATE OVERNIGHT...SO THE POSSIBILITY OF LOCALLY HEAVY SHOWERS CANNOT BE RULED OUT...ESPECIALLY IF ANY KIND OF SIGNIFICANT ORGANIZED CONVECTION CAN MANAGE TO FORM UPSTREAM THIS AFTERNOON OR EVENING. LOWS EARLY TUESDAY WILL BE GENERALLY IN THE 50S...OR SOME 10-15 DEG ABOVE NORMAL.
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&& .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
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THE WAVY QUASI EAST/WEST FRONTAL BOUNDARY WILL BECOME QUASI- STATIONARY OVER THE AREA TUESDAY...AND THE DUAL TO TRI-LAYERED CLOUD COVER SURROUNDING IT SHOULD BE BKN-OVC FOR MUCH OF THE TIME. ANY HOLES AND LOCALIZED ISOLATION THAT OCCUR WILL WORK ALONG WITH THE HIGH PWAT AIR /IN EXCESS OF 1 INCH/ TO BUBBLE UP SCTD- NUMEROUS...MAINLY AFTERNOON AND EARLY EVENING SHRA/TSRA WITH BRIEF DOWNPOURS AND GUSTY WINDS OF 30-40 MPH POSSIBLE. HIGH TEMPS TUESDAY WILL BE 8-10F COOLER THAN MONDAY ACROSS THE NW HALF OF THE STATE...BUT JUST 2-5 DEG LOWER THAN THE PRIOR DAY ACROSS THE SCENT ZONES AND LOWER SUSQ REGION. BASIN AVG RAINFALL TUESDAY SHOULD BE 2-4 TENTHS WITH LOCALLY OVER ONE-HALF OF AND INCH WHERE SEVERAL SHRA AND TSRA OCCUR. MAINLY CLOUDY SKIES...AND LINGERING...MAINLY EVENING SHOWERS/ISOLATED TSRA ARE IN STORE FOR TUESDAY NIGHT.
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&& .LONG TERM /WEDNESDAY THROUGH MONDAY/... THE FRONT THAT WILL BE SLOW TO SETTLE THROUGH THE REGION LOOKS LIKE IT WILL BECOME VERY DIFFUSE OR EVEN WASH OUT ALTOGETHER OFF TO OUR SOUTH AS THE UPPER RIDGE BUILDS OVER TOP OF IT THROUGH MID WEEK. THERE COULD BE A LINGERING SHOWER OR THUNDERSTORM OVER SOUTHERN AREAS WEDNESDAY...BUT THE TREND FROM MID WEEK ONWARD WILL BE FOR IMPROVING CONDITIONS AS THE UPPER RIDGE BUILDS...AND BY WEEK`S END TAKES ON THE LOOK OF A REX BLOCK OVER THE EASTERN US. INTERESTING TO NOTE THAT THE MODELS STILL WANT TO DEVELOP A TROPICAL SYSTEM OFF THE SERN COAST NEAR THE BAHAMAS LATER IN THE WEEK. NHC HAS BEEN ISSUING SPECIAL STATEMENTS ON THIS POTENTIAL. TEMPERATURES THIS WEEK WILL CONTINUE TO RUN WELL ABOVE AVERAGE AS WE SEE TO HAVE SUDDENLY TRANSITIONED INTO AN EARLY SUMMER TYPE PATTERN. && .AVIATION /19Z MONDAY THROUGH SATURDAY/...
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HIGH PRESSURE JUST OFF THE EAST COAST WILL MAINTAIN VFR CONDS WITH EXCELLENT VSBYS THROUGH THIS REST OF THIS AFTERNOON. SOUTHWEST WINDS WILL AVERAGE 10-15 MPH THIS AFTERNOON ACROSS CENTRAL AND WRN PENN TAF SITES...WHILE MORE OF A SOUTH TO SOUTH- SOUTHWEST IS EXPECTED ACROSS THE LOWER SUSQ VALLEY...TO THE EAST OF A DEVELOPING LEE TROUGH. GUSTS OF 22-28 MPH WILL BE COMMON THROUGH ABOUT 23Z BEFORE WINDS AND GUSTS GRADUALLY DECREASE. AN APPROACHING COLD FRONT WILL TRIGGER SCT SHRA/TSRA ACROSS NORTHWEST PA THIS EVENING WITH A BRIEF VIS REDUCTION POSSIBLE AT KBFD. BRIEF REDUCTIONS POSSIBLE FURTHER SE BY TUE AM. MORE NUMEROUS SHOWERS AND SCTD TSRA WILL DEVELOP TUESDAY AFTERNOON AS THE FRONTAL BOUNDARY STRETCHES OUT NEARLY EAST/WEST ACROSS THE REGION AND AN UPPER LEVEL DISTURBANCE RIDES EAST OVER IT. EXPECT MAINLY HIGH END MVFR TO VFR CIGS AND VSBYS...BUT BRIEF IFR CIGS AND VSBYS POSSIBLE IN THE HEAVIER SHRA/AND ANY TSRA. CIGS AND VSBYS SHOULD GRADUALLY LOWER BY ABOUT 1 FLIGHT CATEGORY TUESDAY NIGHT WITH AREAS OF LIFR ACROSS THE NRN AND WRN MTNS...AND MVFR TO IFR CIGS THROUGHOUT THE CENTRAL MTNS AND SUSQ VALLEY. VSBYS SHOULD BECOME MAINLY MVFR WITH AREAS OF IFR VSBYS IN FOG. OUTLOOK... WED...AM LOW CIGS POSS KJST. THU-FRI...NO SIG WX EXPECTED.
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&& .FIRE WEATHER...
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A WARM...DRY...AND GUSTY SOUTHWESTERLY FLOW WILL CONTINUE UNTIL SHORTLY BEFORE DUSK. MIN RH`S WILL BE BELOW 30% AND THE GUSTY SW WINDS OF 20 TO 25 KTS HAS LED TO A RED FLAG WARNING FOR APPROX THE EASTERN THIRD OF THE STATE THROUGH 00Z. RHS AND CLOUDS WILL STEADILY INCREASE TONIGHT WITH SCATTERED LATE NIGHT SHOWERS DEVELOPING SOUTH AND EAST ACROSS THE REGION AS A COLD FRONT SAGS SLOWLY SE FROM THE GLAKES. THE SHOWERS WILL BECOME MORE NUMEROUS WITH COMPARATIVELY HIGHER RH VALUES /THAN MONDAY/ DURING THE MIDDAY AND AFTERNOON HOURS TUESDAY WITH SCATTERED TSRA AS THE FRONT BECOMES NEARLY STATIONARY ACROSS THE REGION.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 8 PM EDT THIS EVENING FOR PAZ037-041- 042-046-051>053-058-059-066. && $$ SYNOPSIS...LAMBERT NEAR TERM...LAMBERT SHORT TERM...LA CORTE LONG TERM...LA CORTE AVIATION...LAMBERT FIRE WEATHER...LAMBERT

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