Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 270004 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 804 PM EDT SAT JUL 26 2014 .SYNOPSIS... A SERIES OF DISTURBANCES WILL MOVE ACROSS THE FORECAST AREA THE SECOND HALF OF THIS WEEKEND AS A DEEP UPPER TROUGH DEVELOPS OVER THE NORTHEASTERN UNITED STATES. THERE WILL BE SEVERAL CHANCES FOR PRECIPITATION...INCLUDING STRONG TO POTENTIALLY SEVERE THUNDERSTORMS SUNDAY INTO SUNDAY NIGHT...BEFORE ANOTHER SHOT OF UNSEASONABLY COOL AIR MOVES IN AND REMAINS OVER THE REGION THROUGHOUT THE NEW WORK WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... MOISTURE FLUX CONVERGENCE INTO EASTERN OH AND WESTERN PA AHEAD OF SEVERAL SHORTWAVE TROFS IS MAINTAINING A LARGE AREA OF SHOWERS AND EMBEDDED THUNDERSTORMS. MOST ACTIVE CONVECTION IS NOW APPROACHING SOUTHERN PORTIONS OF THE LAUREL HIGHLANDS AND WEST CENTRAL MOUNTAINS WITH SOME HEAVY DOWNPOURS AND LIKELY SUB SEVERE WIND GUSTS. SLOW DECREASE IN STRENGTH IS ANTICIPATED THROUGH THE EVENING AS DAYTIME HEATING IS LOST BUT LL CONVERGENCE MAINTAINS THE OVERALL AREA OF CONVECTION SPREADING EASTWARD. GOING FORECAST IN GOOD SHAPE THIS EVENING FOR CURRENT RADAR TRENDS. NO SIG UPDATES AT THIS TIME. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... SUNDAY SHAPING UP TO BE A POTENTIALLY BUSY DAY AS AN UNSEASONABLY STRONG UPPER LOW DROPS THROUGH THE LOWER LAKES AND TAKES AIM AT THE LOCAL AREA. SPC HAS OUTLOOKED REGION JUST TO OUR SW /INCLUDING PORTIONS OF OH-KY-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/SHEAR THE SYSTEM WILL HAVE AVAILABLE. WHERE THE OHIO VALLEY DEVELOPMENTS TAKE PLACE TONIGHT WILL HAVE MUCH TO SAY ABOUT HOW FAR NORTH INTO CENTRAL PA THE STRONGEST STORMS WILL MANAGE TO MOVE. BUT THIS SYSTEM IS ROBUST ENOUGH THAT WE MAY INITIALLY SEE ONE WAVE OF STORMS DEVELOP ACROSS THE SOUTH DURING THE DAY...WITH A SECOND WAVE DEVELOPING FURTHER NORTH LATE IN THE AFTERNOON INTO THE EVENING. THE SOUTHERN STORMS LOOK TO HAVE THE HIGHEST POTENTIAL FOR LARGE HAIL/DAMAGING WINDS/EVEN AN ISO TORNADO...WITH NORTHERN STORMS MAINLY WIND PRODUCERS. FIRST HALF OF THE EVENING SHOULD STILL BE QUITE BUSY WITH ONGOING STORMS...WITH DECREASING ACTIVITY INTO THE OVERNIGHT BEHIND THE COLD FRONT. && .LONG TERM /MONDAY THROUGH SATURDAY/... RAINFALL WILL DIMINISH IN COVERAGE MONDAY AS THE FRONTAL BOUNDARY MOVES EAST OF THE AREA. LINGERING SHOWERS ARE MOST LIKELY OVER EASTERN PA WITH THE WESTERN CWA DRYING OUT. A DEEP TROUGH OVER THE EASTERN US WILL CONTINUE THROUGH THE UPCOMING WEEK...WITH THE AXIS WAFFLING EAST TO WEST AS INDIVIDUAL SHORT WAVES MOVE THROUGH. ONLY PAINTED ISOLATED SHOWERS IN THE LONG TERM AS SPECIFICS WILL DEPEND ON THE DAY TO DAY LOCATION OF RIPPLES MOVING THROUGH THE TROUGH. WE COULD SEE MORE SIGNIFICANT MOISTURE RETURN NEXT WEEKEND AS THE GFS/GEFS/ECMWF ALL HINT AT THE UPPER TROUGH RETROGRADING A BIT...PAVING THE WAY FOR A SOUTH TO SOUTHEAST FETCH OF ATLANTIC MOISTURE WORKING INTO THE NORTHEAST. 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 /00Z SUNDAY THROUGH THURSDAY/...
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TROUGH OF LOW PRES APPROACHING FROM THE GRT LKS WILL SPREAD SCT SHRA AND A FEW TSRA INTO CENTRAL PA OVERNIGHT. RADAR AT 00Z SHOWS FIRST BATCH OF SHRA/TSRA MOVING THRU SW PA...WITH ADDITIONAL ACTIVITY LIKELY TO FOLLOW LATER TONIGHT. FOR MOST OF CENTRAL PA...THE BEST CHC OF PRECIP WILL COME BTWN 04Z-09Z WITH PASSAGE OF UPPER TROUGH. BRIEF VIS REDUCTIONS ARE POSSIBLE IN ANY SHRA/TSRA. HOWEVER...THE LARGER AVIATION CONCERN IS THE POSSIBILITY OF LOW CIGS DEVELOPING TOWARD DAWN AT KBFD...THE RESULT OF INCREASING LOW LVL MOISTURE ASCENDING THE HIGH TERRAIN OF NW PA. A BAND OF MODERATELY STRONG WINDS ALOFT PRECEDING THE TROUGH COULD PRODUCE MARGINAL LLWS OVERNIGHT...MAINLY OVR THE NW MTNS. ANY EARLY LOW CIGS SHOULD MIX OUT OVR THE N MTNS ON SUNDAY...LEAVING WIDESPREAD VFR CONDS FOR THE REST OF THE DAY. MAIN AVIATION CONCERN WILL COME LATE SUNDAY AND SUNDAY NIGHT...AS A POTENT LOW PRES SYSTEM APPROACHES FROM THE GRT LKS. LATEST MDL DATA POINTS TOWARD THE POSSIBILITY OF SOME STRONG TSRA ACROSS SOUTHERN PA DURING THE LATE AFTN AND EVENING. FURTHER NORTH...THE THREAT OF STRONG WGUSTS IS LOWER. HOWEVER...VSBY REDUCTIONS STILL APPEAR LIKELY IN SHRA/TSRA SUNDAY NIGHT. OUTLOOK... MON...AM LOW CIG POSS W MTNS. TUE-THU...NO SIG WX EXPECTED.
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&& .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RXR NEAR TERM...DEVOIR/RXR SHORT TERM...RXR LONG TERM...LA CORTE/TYBURSKI AVIATION...FITZGERALD

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