Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 052208 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 508 PM EST THU MAR 5 2015 .SYNOPSIS... A WAVE OF LOW PRESSURE WILL TRACK SOUTH OF PENNSYLVANIA THIS EVENING. HIGH PRESSURE WILL BUILD SOUTHEAST INTO THE STATE FRIDAY AND SATURDAY. A STRONG UPPER-LEVEL RIDGE WILL BUILD INTO THE REGION EARLY NEXT WEEK. THIS SHOULD PROVIDE GENERALLY FAIR WEATHER AND SEVERAL DAYS OF NEAR NORMAL TEMPERATURES AND RELATIVELY DRY WEATHER. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... BACK EDGE OF SNOW HAS EXITED LANCASTER CO AS OF 22Z. MAY LET REMAINING WARNINGS ACROSS THE LOWER SUSQ VALLEY RIDE UNTIL EXPIRATION AT 00Z...AS WEB CAMS SUGGEST MANY ROADS REMAIN IN POOR CONDITION. VISIBLE IMAGERY SHOWS CLEARING SKIES ACROSS THE NW MTNS AT 22Z...AND EXPECT THIS CLEARING TREND TO SPREAD SE THIS EVENING AS ARCTIC HIGH PRES SYSTEM OVERSPREADS THE STATE. DIMINISHING WIND...CLEARING SKIES AND FRESH SNOW COVER WILL RESULT IN NEAR RECORD LOW TEMPERATURES...RANGING FROM 5-10 BLW ZERO OVR THE NW MTNS...TO THE LOWER SINGLE DIGITS ACROSS THE LOWER SUSQ VALLEY. AT THIS POINT...WE ARE COUNTING ON THE WIND TO DROP OFF ENOUGH TO MINIMIZE WIND CHILLS...SO NO HEADLINES ARE PLANNED AT THIS TIME. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... HIGH PRESSURE WILL PROVIDE A MUCH BRIGHTER DAY FRIDAY. FORECAST SOUNDINGS SUGGEST THE POTENTIAL FOR SOME STRATOCU TO GATHER UNDER THE STRONG SUBSIDENCE INVERSION...BUT A FAIR AMOUNT OF SUNSHINE SHOULD MANAGE TO MIX WITH ANY CLOUDS THAT FORM. ONCE AGAIN IT WILL BE MUCH COLDER THAN NORMAL WITH HIGHS GENERALLY IN THE 20S. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... SFC HIGH PRESSURE RIDGE AXIS WILL MIGRATE EWD ACROSS THE MID ATLANTIC REGION FRIDAY NIGHT AND SETTLE INTO THE SOUTHEAST STATES ON SATURDAY. AN INCREASE IN SW GRADIENT WINDS AND CLOUDS ARE EXPECTED ACROSS THE NW HALF OF THE CWA IN ADVANCE OF A WEAK LOW MOVING ACROSS THE GREAT LAKES. MEANWHILE MAINLY CLEAR SKIES AND LIGHTER WINDS ACROSS THE LOWER SUSQ VALLEY SHOULD PREVAIL NEAR THE DEPARTING SFC RIDGE. THIS PATTERN FAVORS A NON-DIURNAL TREND WITH LOWS IN THE MID TEENS OCCURRING EARLY ACROSS THE NW MTNS FRIDAY NIGHT WITH A STEADY TO SLOW RISE INTO SATURDAY MORNING. A MORE TYPICAL NOCTURNAL TEMP CURVE SHOULD ALLOW TEMPS TO FALL TO AROUND 10F OVER THE LOWER SQV. BROAD UPPER CYCLONIC FLOW WILL CONTINUE INTO EARLY NEXT WEEK AS ADDITIONAL SHORTWAVE IMPULSES MOVE FROM CENTRAL CANADA THROUGH THE NORTHERN TIER OF THE U.S. THERE ARE FEWER DIFFERENCES NOTED OVERALL COMPARED TO PREVIOUS MODEL CYCLES WITH RESPECT TO THE TIMING AND DEPTH OF EACH IMPULSE. ONE IMPULSE WILL DRIVE A SURFACE WAVE AND ASSOCIATED FRONT THROUGH THE GREAT LAKES REGION ON SAT AND THEN INTO NEW ENGLAND ON SUN. AN ADDITIONAL IMPULSE WILL TAKE A SIMILAR TRACK THROUGH THE GREAT LAKES LATER SUN INTO EARLY MON ALONG WITH A WEAK FRONT. GIVEN THE FAST DEEPER LAYER WEST NORTHWEST FLOW OVER THE REGION...THE AMPLITUDE OF EACH IMPULSE SHOULD BE RATHER SMALL WITH MOISTURE AVAILABILITY QUITE LIMITED. THEREFORE EXPECT OCCASIONAL SNOW SHOWERS MAINLY OVER THE HIGHER TERRAIN OF THE NORTHERN ALLEGHENIES WITH 48 ACCUMS OF 1-2" POSSIBLE OVER THE NW MTNS BY 12Z MON. THE MODELS AND ENSEMBLE MEANS ARE AGREEABLE/CONSISTENT WITH THE MAIN THEMES OF THE LARGE SCALE PATTERN INTO NEXT WEEK. THESE INCLUDE AN INCREASINGLY ZONAL/PROGRESSIVE NRN STREAM FLOW ACROSS SRN CANADA...AND SRN ROCKIES/PLAINS INTO MEXICO MEAN TROUGH AND STRONG RIDGE E OF THE BAHAMAS. AS THE MEAN PATTERN ALOFT BECOMES INCREASINGLY FLATTER...CONFIDENCE IS RELATIVELY HIGH IN A MAINLY DRY PERIOD WITH STEADILY INCREASING/MODERATING TEMPERATURES TO AT OR SLIGHTLY ABOVE EARLY-MID MARCH CLIMATE NORMALS. && .AVIATION /22Z THURSDAY THROUGH TUESDAY/... MOST OF THE FLYING AREA WILL REMAIN VFR NORTH OF THE BANDED PRECIPITATION THAT IS CAUSING MVFR-IFR/LIFR FROM JOHNSTOWN EAST THROUGH THE LOWER SUSQ VALLEY. CONDITIONS WILL SLOWLY IMPROVE OVER SOUTHERN AND SOUTHEASTERN AREAS THIS AFTERNOON...WITH LANCASTER-HARRISBURG LIKELY BEING THE LAST TO ENJOY IN THE IMPROVING CONDITIONS. EXPECT MOST TERMINALS TO BE VFR OVERNIGHT. JST MAY BE THE EXCEPTION WITH LOW CLOUDS HANGING IN TOUGH UNDER THE UPSLOPE FLOW. OUTLOOK... FRI-SAT...MAINLY VFR. SUN-MON...MVFR WITH CHC -SHSN MAINLY NORTH AND WEST. VFR SE. TUE...NO SIG WX. && .CLIMATE... DAILY RECORD LOWS ARE IN SERIOUS JEOPARDY TONIGHT AT MANY LOCATIONS. THE RECORD LOW FOR MARCH 6TH AT HARRISBURG IS 7F SET BACK IN 1901 AND -1F AT WILLIAMSPORT SET IN 1978. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR PAZ036- 057-059-063>066. && $$ SYNOPSIS...LA CORTE NEAR TERM...FITZGERALD/LA CORTE SHORT TERM...LA CORTE LONG TERM...STEINBUGL AVIATION...LA CORTE CLIMATE...

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