Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 210545 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 145 AM EDT TUE APR 21 2015 .SYNOPSIS... A COLD FRONT WILL PUSH EAST OF THE AREA EARLY THIS MORNING. A LARGE UPPER LEVEL LOW OVER THE GREAT LAKES WILL SLOWLY EDGE EASTWARD TO NORTHERN NEW ENGLAND BY LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... HEAVY SHOWERS AND A FEW LINGERING LIGHTNING STRIKES OBSERVED ACROSS FROM THE SUSQ RIVER EASTWARD AT 05Z ALONG AXIS OF LL JET AND ASSOC BAND OF ANOMALOUS PWATS. COLD FRONT...WHICH IS BISECTING THE STATE AT 05Z FROM ARND KUNV TO KAOO...SHOULD EXIT THE EASTERN COUNTIES BY ARND 09Z. MUCH DRIER AIR HAS ALREADY ARRIVED OVER THE ALLEGHENY PLATEAU WITH DWPTS FALLING INTO THE L40S. PASSAGE OF UPPER LVL SHORTWAVE WILL SUSTAIN A FEW LINGERING POST-FRONTAL -SHRA INTO THE PREDAWN HOURS. HOWEVER...LATEST RAP/HRRR INDICATE THE LAST OF THE -SRHA SHOULD BE EXITING THE EASTERN COUNTIES BY ARND 11Z. EXPECT PARTIAL CLEARING TO DEVELOP EAST OF THE MTNS TOWARD DAWN...AS DRIER WESTERLY FLOW ARRIVES. FURTHER WEST...SHALLOW LYR OF MOISTURE ASCENDING THE MTNS WILL LIKELY RESULT IN BKN STRATOCU PERSISTING OVR THE ALLEGHENIES. TWEAKED MIN TEMPS A BIT BASED ON LATEST LAMP/RAP GUIDANCE. READINGS BY DAWN SHOULD RANGE FROM ARND 40F OVR THE HIGH TERRAIN OF THE ALLEGHENIES...TO THE M50S SE OF HARRISBURG. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/... MDL DATA INDICATES CENTRAL PA WILL BE IN A REGION OF LG SCALE SUBSIDENCE/SFC RIDGING LATE THIS MORNING WITH DRY WX ANTICIPATED. HAVE REDUCED POPS SIGNIFICANTLY BTWN 12Z-18Z. MDL SOUNDINGS AND UPSTREAM SATL IMAGERY IMPLY THERE WILL BE A FAIR AMT OF SUNSHINE LATER THIS MORNING...ESP EAST OF THE MTNS...WITH PSUNNY SKIES ACROSS THE NW MTNS. DIURNAL HEATING/DEEPENING BLYR DEPTH WILL RESULT GUSTY WSW WINDS DEVELOPING DURING THE LATE AM AND AFTN HOURS. BUFKIT SOUNDINGS SUPPORT WIDESPREAD GUSTS TO ARND 25KTS BY AFTN. ANOMALOUSLY COLD MID LVL TEMPS WILL PROMOTE DIURNAL CONVECTION DURING THE AFTN...PRIMARILY OVR THE NW MTNS. LACK OF DEEP MOISTURE WILL RESULT IN LIGHT RAINFALL AMTS. HOWEVER...HAVE BUMPED UP POPS TO BTWN 60-70PCT ACROSS THE NW MTNS BASED ON ENSEMBLE QPF OUTPUT. PER SPC OUTLOOK...HAVE INCLUDED THE CHC OF A PM TSRA OVR THE NW COUNTIES...WHERE MDL SOUNDINGS BECOME MARGINALLY UNSTABLE BTWN 18Z-00Z. ENS MEAN 8H TEMPS SUPPORT MAX TEMPS TODAY FROM AROUND 50F OVR THE NW MTNS TO THE L60S ACROSS THE LOWER SUSQ. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... THE LONG TERM PATTERN WILL BE DOMINATED BY A LARGE UPPER LEVEL LOW MOVING THROUGH THE NORTHERN GREAT LAKES...AND THROUGH SOUTHERN CANADA MIDWEEK TO THE WEEKEND. THERE IS GOOD MODEL CONSENSUS THROUGH THE MID RANGE PERIOD. AFTER THE FRONT LIFTS OUT BY TUESDAY MORNING THE UPPER LOW HANGS AROUND S CANADA/NEW ENGLAND FOR SEVERAL DAYS KEEPING FAIRLY BRISK W/NW FLOW ACROSS PA. THIS WILL BRING A STEADY STREAM OF COLDER AIR AS TEMPS SLOWLY SLIP A BIT LOWER EACH DAY WITH BELOW NORMAL READINGS FOR A SEVERAL DAY PERIOD LINGERING INTO NEXT WEEKEND. PROXIMITY OF UPPER LOW WILL ALSO KEEP MENTION OF SCT SHOWERS IN THE FORECAST. A SHORTWAVE SHOULD DROP THROUGH THE REGION WEDNESDAY AFTERNOON INTO THURSDAY MORNING. THIS COULD DROP EVEN COLDER AIR INTO THE REGION BRINGING THE POSSIBILITY OF SNOW TO THE NW TO THE CENTRAL REGIONS OF PA. THE MODELS ARE BECOMING CLOSER TO A CONSENSUS SOLUTION...HOWEVER SOLUTION IS TRENDING TOWARD THE UPPER LEVEL LOW TO BECOME QUASI-STATIONARY AND SLOWLY SPINNING OVER QUEBEC.WITH ONLY A SLIGHT CHANCE FOR PRECIPITATION NEXT WEEKEND. THE MOVEMENT OF THE LOW WILL DOMINATE THE PATTERN NEXT WEEK WITH IT POSSIBLY RETROGRADING AND SWINGING ANOTHER TROUGH THROUGH THE REGION NEXT WEEK. && .AVIATION /05Z TUESDAY THROUGH SATURDAY/... ASIDE FROM BRIEF IFR VIS IN +TSRA INVOF MDT/LNS THRU 06Z...EXPECT MVFR/VFR CONDITIONS TO PREVAIL OVERNIGHT AND INTO TUESDAY. SFC WNDS FROM 250 TO 300 DEGREES WILL BECOME GUSTY AT 25-30KTS BY TUESDAY MORNING WITH PREDOMINATELY SCT TO BKN MVFR TO VFR CIGS. OUTLOOK... WED-SAT...PERSISTENT NW FLOW PATTERN WILL FAVOR MVFR CIGS OVER THE NW AIRSPACE IN ZOB SECTOR...WITH MAINLY VFR CONDITIONS PREVAILING IN ZNY DOMAIN. ISOLD TO SCT SHOWERS WILL BE POSSIBLE ACROSS ALL OF THE AIRSPACE THROUGH THE REMAINDER OF THE WEEK. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD/LA CORTE NEAR TERM...FITZGERALD SHORT TERM...FITZGERALD/CERU LONG TERM...CERU/RXR AVIATION...STEINBUGL

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