Area Forecast Discussion
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPBZ 301733 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 133 PM EDT SAT MAY 30 2015 .SYNOPSIS... WARM AND HUMID CONDITIONS WILL CONTINUE UNTIL THE PASSAGE OF A STRONG COLD FRONT LATE SUNDAY. COOLER WEATHER WILL SETTLE OVER THE REGION TO START THE WORK WEEK. && .NEAR TERM /THROUGH SUNDAY/... SEVERAL ADJUSTMENTS MADE TO THE NEAR TERM FORECAST AS CONVECTION HAS ALREADY BEGUN TO DEVELOP WHERE CAPPING IS NO LONGER PRESENT OVER OHIO. WHILE COVERAGE OF CONVECTION SHOULD BE RATHER ISOLATED THROUGH NOON...SURFACE HEATING AND DESTABILIZATION SHOULD SUPPORT AN INCREASE IN COVERAGE THIS AFTERNOON. WITHOUT THE PRESENCE OF A STRONG LIFTING MECHANISM AND WEAK SHEAR...THE ENVIRONMENT MAINLY SUPPORTS THE RUN-OF-THE-MILL SUMMER-TIME AIRMASS THUNDERSTORMS. HOWEVER...WITH STEEPENING LOW LEVEL LAPSE RATES...ANY OUTFLOW BOUNDARIES COULD SUPPORT A STRONG STORM OR TWO THIS AFTERNOON. THIS IS SUPPORTED BY THE SPC MARGINAL RISK TODAY. IN REGARD TO THE FORECAST...HAVE UPPED POPS JUST ABOUT 10% THOUGH THE AFTERNOON AND MADE ADJUSTMENTS TO CLOUD COVER...DIURNAL TEMPS...AND DEWPOINTS THROUGH THIS EVENING BASED ON LATEST OBSERVATIONS...TRENDS...AND HI RES MODEL OUTPUT. DIURNAL CONVECTION WILL DIMINISH WITH THE LOSS OF HEATING TONIGHT AS THE FRONT REMAINS WEST OF THE AREA. TEMPERATURES SHOULD STILL TREND ABOVE NORMAL SUNDAY MORNING AS THE VORT MAX SHIFTS NORTHWARD TO LAKE ERIE AND SW FLOW CONTINUES. WHILE THE SURFACE LOW WILL MOVE RIGHT ACROSS OHIO AND WESTERN PA ON SUNDAY...SUPPORTING THE LIKELY POPS IN THE FORECAST...THE BULK OF THE UPPER LEVEL SUPPORT AND MID LEVEL MOISTURE WILL REMAIN NORTH...SO QPF DOES NOT LOOK OVERLY IMPRESSIVE. THE ONLY EXCEPTION WOULD BE IN THE HIGHER TERRAIN WITH OROGRAPHIC ENHANCEMENT. PRECIPITATION AND CLOUD COVER SHOULD HOLD TEMPERATURES A BIT DOWN COMPARED TO TODAY...BUT ARE STILL FORECAST TO BE ABOVE SEASONAL AVERAGES. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... SURFACE LOW DIRECTLY OVERHEAD SUNDAY NIGHT VERTICALLY TILTED BACK TOWARDS THE THUMB OF MICHIGAN. PLACEMENT OF THE MID-LEVEL LOW IS FAVORABLE FOR THE DRY SLOT...CLEARLY EVIDENT ON MID-LEVEL MODEL RH FIELDS...TO MOVE IN LATE SUNDAY EVENING AND SQUASH WIDESPREAD PRECIPITATION. MID-LEVEL LOW SHIFTS NORTHEAST OF THE AREA IN THE PRE-DAWN HOURS MONDAY...ALLOWING STRONG COLD AIR ADVECTION TO INVADE THE AREA...SETTING A COOLER TONE TO THE NEW WORK WEEK. 00Z GFS HAS 850MB TEMPERATURES DROPPING ABOUT 1C/HR TO 5-7C BY DAWN MONDAY. THIS STEEPENS THE LOW-LEVEL LAPSE RATES AND TRAPS COPIOUS LOW-LEVEL MOISTURE UNDER AN INVERSION NEAR 800MB. STRATO-CU WILL BE STUBBORN MIXING OUT MONDAY...HOLDING FOR MOST OF THE DAY. MOISTURE DEPTH WONT BE CONDUCIVE FOR MUCH PRECIPITATION DEVELOPMENT MONDAY...BUT DEEPER MOISTURE OVER THE HIGH TERRAIN OF MD/WV/PA DOES WARRANT THE NEED FOR CHANCE POPS. CURRENT FORECAST CALLS FOR TEMPS A FEW NOTCHES BELOW AVERAGE. UPPER-LEVEL LOW DEEPENS AND CUTS OFF NORTH OF LAKE HURON MONDAY EVENING. THIS WILL WORK TO QUICKLY LIFT THE REMAINING MOISTURE ASSOCIATED WITH THE MID-LEVEL LOW NORTH AND OUT OF THE AREA. THE FLUSHING MECHANISM OF THE UPPER-LOW WILL PAVE THE WAY FOR DRIER AIR TO MOVE IN WITH A BUILDING SURFACE HIGH. TUESDAYS HIGH TEMPERATURES WILL RECOVER NICELY WITH MORE SUN EXPECT THAN MONDAYS OFFERING...BUT COOL NORTHWEST FLOW ALOFT MEANS A RETURN TO WELL-ABOVE NORMAL TEMEPRATURES IS NOT ANTICIPATED FOR TUESDAY. TAX && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
-- Changed Discussion --
SURFACE HIGH PRESSURE WILL BRING DRY AND SEASONAL CONDITIONS MID WEEK. A WARMING TREND INTO NEXT WEEKEND AS HEIGHTS BUILD ALOFT. INCREASING DEEP MOISTURE AND AN APPROACHING COLD FRONT WILL BRING THUNDERSTORM CHANCES LATER FRIDAY AND SATURDAY. OVERALL CLOSE TO LATEST WPC PROGS.
-- End Changed Discussion --
&& .AVIATION /17Z SATURDAY THROUGH THURSDAY/...
-- Changed Discussion --
SCATTERED SHOWERS AND STORMS WILL BRING MVFR AT TIMES TO PORTS INTO THE EARLY EVENING...WITH BRIEF IFR POSSIBLE. LACK OF DAYTIME HEATING WILL HELP DIMINISH SHOWERS TOWARD 00Z. THEN GENERAL VFR OVERNIGHT ALTHOUGH SOME MFVR FOG MAY DEVELOP BEFORE DAYBREAK...LEFT OUT OF TERMINALS FOR NOW. AS COLD FRONT SLOWLY SINKS SOUTH LATER TONIGHT AND SUNDAY INCREASING SHOWERS WITH MVFR CIGS AT TIMES. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... RESTRICTIONS WILL BE POSSIBLE WITH WITH A SLOW MOVING COLD FRONT AND LOW PRESSURE INTO MONDAY.
-- End Changed Discussion --
&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.