Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 260920 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 520 AM EDT SAT JUL 26 2014 .SYNOPSIS... A SERIES OF DISTURBANCES WILL MOVE ACROSS THE FORECAST AREA THIS WEEKEND AS A DEEP UPPER TROUGH DEVELOPS OVER THE NORTHEASTERN UNITED STATES. THERE WILL BE SEVERAL CHANCES FOR PRECIPITATION BEFORE ANOTHER SHOT OF UNSEASONABLY COOL AIR MOVES IN AND REMAINS OVER THE REGION THROUGHOUT THE NEW WORK WEEK. && .NEAR TERM /THROUGH TONIGHT/... A POTENT SHORTWAVE CAN BE SEEN ON WATER VAPOR IMAGERY SLIDING EAST THROUGH THE REGION. SHORT RANGE OPERATIONAL MODELS AREN`T DOING PARTICULARLY WELL HANDLING THE SMALL TIGHT AREA OF LIGHT SHOWERS ASSOCIATED WITH THE SYSTEM. WITH THE SHORTWAVE SLIDING THROUGH EARLY IN THE DAY...RIDGING ALOFT SHOULD GIVE A RESPITE IN THE SHOWER ACTIVITY. AS A RESULT...I WENT BELOW MODEL POPS AS HEIGHTS ALOFT RISE AHEAD OF THE NEXT TROUGH THAT WILL BE DIGGING INTO THE GR LAKES. MID LEVEL LAPSE RATES WILL BE FAIRLY STEEP SO I CANNOT RULE OUT A STRAY SHOWER OR T-STORM...BUT THINKING IS THAT COVERAGE WILL BE SMALL ENOUGH TO AVOID MENTION IN MOST AREAS. 850 TEMPS POP UP TO 16-18C WHICH SHOULD BE SUITABLE FOR DAYTIME HIGHS TO HIT 80 OR ABOVE OVER MOST OF THE AREA. MORE CLOUDS UP NORTH WILL PROBABLY KEEP READINGS IN THE UPPER 70S. HUMIDITY WILL BE ON A SLOW RISE...BUT NOT TERRIBLE GIVEN THAT WE ARE IN THE HEIGHT OF THE CLIMATOLOGICAL SUMMER. SPC HAS A MODERATE RISK FOR A GOOD CHUNK OF IL-IN EXPECTING AN MCS TO FORM AHEAD OF A COLD FRONT THAT WILL BE MOVING INTO THE MIDWEST. THESE DEVELOPMENTS WILL HAVE TO BE CLOSELY MONITORED FOR SOUTHWESTERN SECTIONS LATER TONIGHT AS MODELS SHOW A RARE LATE NIGHT SURGE OF INSTABILITY MOVING INTO WESTERN AREAS. WITH CONVECTIVE PLACEMENT CONFIDENCE BEING LOW AT THIS RANGE...I OPTED FOR CHANCE POPS CENTERED MAINLY AFTER MIDNIGHT. && .SHORT TERM /SUNDAY/... SUNDAY COULD BE A BUSY DAY AS AN UNSEASONABLY STRONG UPPER LOW DROPS THROUGH THE LOWER LAKES AND TAKES AIM AT THE LOCAL AREA. SPC HAS OUTLOOKED MUCH OF KY AND WV WITH A MODERATE RISK WHICH LOOKS REASONABLE GIVEN THE STRENGTH OF THE APPROACHING DYNAMICS AND INSTABILITY. WE COULD BE VULNERABLE LOCALLY INTO THE EVENING GIVEN THE EXPECTED TIMING OF THE COLD FRONT ENTERING THE REGION AND THE AMOUNT OF UPSTREAM INSTABILITY THE SYSTEM WILL HAVE AVAILABLE. WHERE THE OHIO VALLEY DEVELOPMENTS TAKE PLACE WILL HAVE MUCH TO SAY ABOUT HOW FAR NORTH INTO CENTRAL PA THE STRONGEST STORMS WILL MANAGE TO MOVE. AS USUAL...BEING ABOUT 2 DAYS OUT...THIS REMAINS MURKY BUT THIS IS A REMARKABLY ROBUST SYSTEM FOR MID SUMMER AND IT WILL BE SURPRISING IF IT PASSES WITHOUT CAUSING SEVERE STORMS. GIVEN CURRENT PROJECTIONS OF WIND AND INSTABILITY...THE AREA SOUTH OF I-80 WOULD SEEM TO BE THE REGION MOST UNDER THREAT FOR SEVERE WEATHER. HIGHS IN THE UPPER 70S TO MID 80S WILL BE TRENDING DOWN OVER THE NEXT FEW DAYS. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... ALL THE ACTION OF NOTE WILL BE PRETTY MUCH OVER BY MONDAY WITH POST FRONTAL SHOWERS GRADUALLY DIMINISHING IN COVERAGE AS THE LOW AND FRONT SLIDE THROUGH NEW ENGLAND. IN A PATTERN THAT LOOKS MORE LIKE IT BELONGS IN MID WINTER THAN MID SUMMER...AN ANOMALOUSLY DEEP UPPER TROUGH IS MADE TO SET UP OVER THE EASTERN US AND REMAIN IN PLACE ALL WEEK. THE DETAILS OF MINOR SHORTWAVES SLIDING INTO THE TROUGH DIFFER AMONG THE AVAILABLE GUIDANCE...BUT DEEP MOISTURE WILL HAVE MOVED EAST SO WE`LL BE LEFT DEALING WITH MAINLY DIURNAL INSTABILITY UNDER THE COLD AIR ALOFT. WE COULD SEE MORE SIGNIFICANT MOISTURE RETURN LATER IN THE WEEK AS THE GFS/GEFS/ECMWF ALL HINT AT THE UPPER TROUGH RETROGRADING A BIT...POSSIBLY PAVING THE WAY FOR SOME ATLANTIC MOISTURE TO WORK UP THE EASTERN SEABOARD. 500MB HEIGHTS IN THE 3-4STD DEV BELOW NORMAL RANGE AND 850 TEMPS OF 1-3 STD DEV BELOW NORMAL POINT TO THE MOST CERTAIN PART OF THE FORECAST BEING SEVERAL DAYS OF TEMPERATURES AVERAGING WELL BELOW NORMAL. A SLOW MODERATION CAN BE EXPECTED BY LATE IN THE WEEK. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... MOST LOCATIONS JUST HAVE SOME HIGH CLDS. WESTERN AND SOUTHERN AREAS MAY SEE A FEW SHOWERS OVERNIGHT. SOME ADJUSTMENTS MADE. 06Z TAFS SENT. EARLIER DISCUSSION BELOW. HIGH PRESSURE AND ASSOC DRY AIR MASS WILL PROVIDE CENTRAL PA WITH VFR CONDS AND LGT WINDS THIS EVENING. EARLIER CONCERN ABOUT LATE NIGHT VALLEY FOG HAS DIMINISHED...AS PLENTY OF MID LVL CLOUDINESS IS NOW EXPECTED TO LIMIT RADIATIONAL COOLING AND THREAT OF FOG. A FEW -SHRA ARE POSSIBLE DURING THE EARLY AM HOURS ACROSS SOUTHERN PA IN ASSOCIATION WITH PASSAGE OF AN UPPER LVL DISTURBANCE...BUT CONFIDENCE IS QUITE HIGH OF VFR CONDS EVERYWHERE THRU DAWN. WIDESPREAD VFR FLYING CONDS EXPECTED FOR THE REST OF SATURDAY...AS HIGH PRESSURE OFF THE E COAST MAINTAINS AN INFLUENCE ACROSS PA. CAN/T RULE OUT AN ISOLD LATE DAY TSRA ACROSS THE NW MTNS...AS SWRLY FLOW DRAWS INCREASING HUMIDITY INTO THE REGION. HOWEVER...ODDS VERY SMALL OF ANY RESTRICTIONS DURING THE DAYLIGHT HOURS. ARRIVAL OF A WARM FRONT SHOULD BRING SCT SHRA/TSRA TO THE AREA SAT NIGHT. BEST CHC OF ANY IMPACTS IN THE FORM OF BRIEF WGUSTS OR VIS REDUCTIONS WOULD BE AT KBFD. OUTLOOK... SUN...SCT TSRA IMPACTS EXPECTED. MON...AM LOW CIG POSS W MTNS. TUE-WED...NO SIG WX EXPECTED. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE NEAR TERM...LA CORTE SHORT TERM...LA CORTE LONG TERM...LA CORTE AVIATION...FITZGERALD/MARTIN

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