Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 021253 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 853 AM EDT MON MAY 2 2016 .SYNOPSIS... LOW PRESSURE WILL MOVE NORTHEAST FROM THE OHIO RIVER VALLEY AND COMBINE WITH A POTENT UPPER LEVEL DISTURBANCE TO PRODUCE NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS TODAY INTO THIS EVENING. A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE COMMONWEALTH LATE TODAY AND TONIGHT. UNSETTLED WEATHER WILL BE IN STORE FOR MUCH OF THE WEEK. MODERATING TEMPERATURES WILL OCCUR INTO THE MIDDLE OF THE UPCOMING WEEK...FOLLOWED BY SOME COOL AND SHOWERY CONDITIONS LATER IN THE WEEK AS A DEEP UPPER LOW MOVES SOUTHEAST FROM THE UPPER GREAT LAKE TO THE CENTRAL APPALACHIANS. && .NEAR TERM /UNTIL 7 PM THIS EVENING/...
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RAIN MOVING OUT QUICKLY AND PARTIAL CLEARING IN SW IS ALREADY WORKING TO HAPPY VALLEY. WILL TWEAK POPS AND SKY A BIT FOR THESE DEVELOPMENTS. PREV... SFC WARM FRONT DEPICTED RATHER NICELY BY LATEST RAP LLVL /SFC-925 MB/ ANALYSIS OF LIFTED INDICES. THE FRONT SNAKES IT WAY FROM NEAR KBTP...TO A WEAK 1010 MB SFC LOW NEAR KDUJ...THEN EXTENDS SOUTH TO KIDI AND ON INTO MD PANHANDLE. WEAKER ELEVATED INSTABILITY AND WIDESPREAD SHRA/TSRA EXTENDED FURTHER NE ACROSS MUCH OF THE CWA AT 10Z...WHERE 850 MB BASED LI/S WERE ABOUT -1 TO -2C. THE HIGHEST POPS /90-100 PERCENT/ WILL BE ACROSS THE NWRN HALF OF THE FCST AREA...BENEATH THE LEFT EXIT REGION OF THE UPR LEVEL JET AND COLLOCATED WITH THE NOSE OF 1-2 SIGMA SOUTHERLY LLJ. OVER THE SERN HALF OF PENN...POPS WILL BE MAINLY IN THE 50-70 PERCENT RANGE DURING THE MID MORNING HOURS AS THE UPPER LEVEL JET MAX RACES NE ACROSS THE CENTRAL AND NRN MTNS. THE INCREASING MOISTURE JUST ABOVE THE SHALLOW COOL AIRMASS ENTRENCHED ACROSS THE CWA WAS LEADING TO SOME 1/2-1SM FOG OVER THE HIGHER TERRAIN OF NRN AND WRNPENN...AND THIS IS EXPECTED TO PERSIST THROUGH SHORTLY AFTER SUNRISE. TEMPS EARLY TODAY WILL VARY FROM THE MID AND UPPER 40S ACROSS THE NORTH AND EAST...TO THE MID 50S OVER THE LAUREL HIGHLANDS. WINDS WILL BE LIGHT AND FROM THE SOUTH TO SOUTHEAST. INITIAL BATCH OF TSRA /IN THE FORM OF MAINLY ELEVATED CONVECTION ACROSS THE NRN MTNS...CENTRAL RIDGE AND VALLEY REGION AND SUSQ VALLEY/ WILL MOVE OFF TO THE NE OF THE REGION LATE THIS MORNING. THERE SHOULD BE A FEW TO SVRL HOUR LULL IN PRECIP...PRIOR TO ANOTHER ROUND OR TWO OF TSRA FORMING ACROSS THE CENTRAL MTNS...IN THE WARM SECTOR AND ALONG A NEARLY NORTH/SOUTH LEE TROUGH. MODELS PAINT MDT INSTABILITY AND MDTLY STRONG LLVL SHEAR ACROSS THE SCENT MTNS AND LOWER SUSQ VALLEY BETWEEN 18-23Z. RAP/NAM EHIS BRIEFLY POKE UP INTO THE 1-1.5 M2/S2 RANGE TO THE SE OF I-81 IN THE LOWER SUSQ VALLEY BETWEEN 20-23Z...BETWEEN THE SFC LEE TROUGH AND QUASI- STNRY/WARM FRONTAL BOUNDARY EXPECTED TO BE LOCATED ABOUT 15 TO 25 SM TO THE EAST OF THE LOWER SUSQ MAINSTEM. PRIOR TO ANY UPSCALE GROWTH IN INDIVIDUAL TSRA TO A BKN LINE /QLCS/...SOME OF THE STORMS COULD CONTAIN WEAK TO MDTLY STRONG MESOS. ANY THREAT FOR A WEAK ISOLATED TORNADO WOULD BE EAST OF THE SUSQ RIVER...INVOF OF BETTER LLVL SHEAR AND LOWER LCL HEIGHTS NEAR THE STNRY FRONT. ANY PRECIP ACROSS THE NW ZONES LATER TODAY WILL BE IN THE FORM OF ISOLATED -SHRA AS THE COLD FRONT IS EXPECTED TO PUSH THROUGH THE KBFD AREA BETWEEN 16-18Z. MAX TEMPS /USING A CONSENSUS MODEL BLEND/ RANGE FORM THE L-M 50S IN THE NW...TO THE UPPER 60S AND LOWER 70S IN THE SOUTHERN VALLEYS.
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&& .SHORT TERM /7 PM THIS EVENING THROUGH 6 AM TUESDAY/... LINGERING LLVL MOISTURE SOME PULSES OF WEAK-MDT UVVEL INVOF OF THE SLOWING CFRONT ACROSS SERN PENN WILL BRING THE CHC FOR A FEW SHOWERS...MAINLY ACROSS THE SE HALF OF THE CWA...WITH HIGHLY ISOLATED SHOWERS ACROSS THE NW MTNS. THE CHC FOR SHOWERS WILL CONTINUE ACROSS THE SE HALF OF THE STATE TUESDAY AS A FEW WEAK SFC WAVE AND UPPER LEVEL IMPULSE RIPPLE NE ALONG THE NEARLY STALLED CFRONT JUST TO OUR SE WITH AN INVERTED TROUGH EXTENDING NNW INTO THE REGION. WILL STRONGLY CONSIDER BOOSTING POPS UP LATE TONIGHT AND TUES MORNING WITH THE NEXT UPDATE...MAINLY NEAR AND TO THE SE OF THE I-81 CORRIDOR WHERE LATEST SREF/GEFS SHOW 90+ PERCENT PROBS FOR 0.10 OF AN INCH OF RAINFL...WITH 60-80 PROBS FOR 0.25 INCH OF QPF. LOW TEMPS TONIGHT WILL RANGE FROM THE COOL UPPER 30S IN THE NORTH...TO THE U40S AND MID 50S ACROSS THE SOUTHERN TIER COUNTIES. && .LONG TERM /TUESDAY THROUGH SUNDAY/... WEDNESDAY SHOULD BE MOSTLY CLOUDY BUT MAINLY DRY A WEAK RIDGE OF HIGH PRESSURE SLIDES EAST ACROSS THE STATE IN THE MORNING. THE PATTERN TURNS QUITE UNSETTLED FOR LATER WEDNESDAY THROUGH FRIDAY AS A DEEP...SLOW-MOVING CLOSED LOW DROPS SE ACROSS THE GREAT LAKES...BEFORE BECOMING SITUATED FROM THE CENTRAL APPALACHIANS TO THE MID ATLANTIC COAST. LATEST 00Z/06Z OPER/ENS GUIDANCE IS FAIRLY CONSISTENT IN EVOLUTION/LOCATION OF THIS UPPER LOW COMPARED TO THE PREVIOUS FEW MODEL RUNS. LATEST GUIDANCE SUGGESTS THAT A STEADY FEED/PLUME OF MOISTURE WILL STREAM NWWD AND SPIRAL AROUND THIS UPPER LOW...WITH THE CURRENT TARGET AREA FOR THE STEADIEST AND HEAVIEST SHOWERS LOCATED SOMEWHERE ACRS CENTRAL AND NRN PENN...EAST TO THE SUSQ VALLEY. PLENTY OF TIME TO WORK OUT THE FINER DETAILS FOR THIS MDTLY HEAVY PRECIP EVENT. UPPER LOW SLOWLY PROGRESSES EASTWARD AWAY FROM THE REGION LATER FRIDAY AND OVER THE UPCOMING WEEKEND AS RIDGE WORKS IN FROM THE WEST. STILL KEPT MENTION OF A SHOWER SE ON SAT. POTENTIAL FOR ANOTHER WAVE TO BRING CHANCE FOR PRECIP ON SUNDAY...BUT MODEL CONFIDENCE DECREASES BY THIS TIME. SO OVERALL...SEASONAL TEMPS MIDWEEK FOLLOWED BY COOLER READING HEADING INTO THE WEEKEND...THEN A WARMING TREND. NOT MUCH SUNSHINE TO BE HAD THIS WEEK WITH PLENTY OF CLOUDS AND INTERMITTENT SHOWERS. && .AVIATION /13Z MONDAY THROUGH FRIDAY/... SHOWERS ARE MOVING EAST AND NORTHWARD WITH IMPROVING CONDITIONS AT JST AND AOO...WITH THE EASTERN TAF SITES STILL MVFR AND LOWER. EXPECT IMPROVING CONDITIONS AT ALL TAF SITES OVER THE NEXT FEW HOURS WITH MAINLY VFR BY 16Z. WINDS WILL SHIFT TO THE WEST FOLLOWING THE STATIONARY BOUNDARY. THERE COULD BE LINGERING MVFR AT BFD. AFTERNOON CONVECTION THROUGH THE SOUTHERN TIER OF COUNTIES IS POSSIBLE MONDAY AFTERNOON...ESPECIALLY THROUGH THE LOWER SUSQUEHANNA. THIS COULD AFFECT MDT/LNS. OUTLOOK... TUE...AM RAIN/LOW CIGS POSS...MAINLY SE. WED...PATCHY AM FOG POSSIBLE. THU-FRI...OCNL SHOWERS/RESTRICTIONS POSSIBLE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...DANGELO/LAMBERT SHORT TERM...LAMBERT LONG TERM...LAMBERT/RXR AVIATION...FITZGERALD/CERU

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