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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPBZ 020855 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 455 AM EDT SAT MAY 2 2015 .SYNOPSIS... HIGH PRESSURE WILL BRING DRIER AND WARMER WEATHER FOR THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... NORTHERLY FLOW CONTINUES TO RULE THE ROOST IN THE UPPER OHIO VALLEY...WITH MUCH MORE STABLE AIR ALREADY TAKING CONTROL OF THE ENTIRE REGION. ON THE HEELS OF NORTHERLY FLOW...SLIGHTLY DRIER DEWPOINTS ARE BEING FILTERED SOUTHWARD. ALONG WITH THE LOSS OF DIURNALLY-DRIVEN INSTABILITY...SKIES ARE RAPIDLY CLEARING IN ALL SECTORS OF THE CWA. THE RESULT LOOKS TO BE A DRY AND CLEAR NIGHT...WITH TEMPERATURES LIKELY FALLING OFF FROM THE READINGS OF LAST NIGHT. OVERNIGHT LOW TEMPERATURES WERE ADJUSTED DOWNWARD A BIT...OWING TO DEWPOINTS ALREADY FALLING OFF INTO THE MID 30S IN OHIO AND NORTHWEST PENNSYLVANIA. A CONTINUATION OF THE WIDE DEWPOINT DEPRESSIONS IN THE BOUNDARY LAYER LOOKS TO BE ON TAP FOR SATURDAY. OTHER THAN A FEW FLAT CUMULUS...SUNNY SKIES AGAIN SEEM TO BE IN STORE. LIKEWISE...STRONG LOW LEVEL LAPSE RATES WILL PROMOTE DECENT MIXING. EVEN THOUGH THERE WILL LIKELY BE A LACK OF LOW LEVEL FLOW RELATIVE TO TODAY...A MIX OUT TO 850 MB SEEMS LIKELY. AS A RESULT...MUCH OF THE REGION WILL AGAIN JUMP INTO THE LOWER 70S AS 850 MB TEMPERATURES JUMP PAST 8C. FRIES && .SHORT TERM /SUNDAY THROUGH MONDAY/...
-- Changed Discussion --
THE WARMING TREND WILL CONTINUE SUNDAY AND MONDAY AS RIDGING CONTINUES TO BUILD OVER THE REGION. FLOW WILL BECOME MORE SOUTHWESTERLY LATE SUNDAY INTO MONDAY WHICH WILL ALLOW FOR ADDITIONAL MOISTURE ADVECTION ACROSS THE REGION. MODELS HAVE TRENDED SLOWER IN TRANSITIONING A BOUNDARY SOUTH AND OVER THE FORECAST AREA WHICH NOW LOOKS MOST LIKELY TO OCCUR LATE MONDAY INTO TUESDAY MORNING. WITH THAT AND CONTINUED WARMING ALOFT...SURFACE BASED LIFT LOOKS LIKELY TO BE CAPPED OFF BETWEEN 6-8KFT AND EXPECT NOTHING MORE THAN AN INCREASE IN CLOUD COVERAGE MONDAY AFTERNOON.
-- End Changed Discussion --
&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
-- Changed Discussion --
THE AFOREMENTIONED BOUNDARY WILL SAG SOUTH ACROSS THE REGION LATE MONDAY INTO TUESDAY WITH PRECIPITATION SPREADING FROM NORTH TO SOUTH AS THIS OCCURS. BY TUESDAY PRECIPITABLE WATER VALUES ARE PROGGED TO BE AROUND 1.25" ON AVERAGE WHICH IS IN THE 90TH-95TH PERCENTILE FOR EARLY MAY. AT THE MOMENT TUESDAY DOES NOT LOOK TO BE OVERLY UNSTABLE WITH CAPE VALUES AROUND 500 JOULES ON AVERAGE ...BUT DO EXPECT THUNDERSTORM DEVELOPMENT DURING THE AFTERNOON WITH THE INCREASED LOW LEVEL INSTABILITY AND SLIGHT COOLING ALOFT AS THE BOUNDARY SAGS SOUTH. ONE CONCERN FOR TUESDAY WILL BE THE POTENTIAL FOR LOCALIZED AREAS OF HEAVY RAIN. WITH HIGH PRECIPITABLE WATER VALUES AND FORECAST SOUNDINGS INDICATING A FAIRLY DEEP WARM CLOUD LAYER...LOW LCLS...WEAK VERTICAL WIND SHEAR AND STEERING LAYER FLOW...AND LOW MBE VELOCITIES...THE POTENTIAL FOR A BACK BUILDING SCENARIO TO SET UP ALONG THE SLOW SOUTHWARD MOVING BOUNDARY IS DEFINITELY THERE. AT THIS POINT IT IS FAR FROM A CERTAINTY BUT DEFINITELY BEARS WATCHING. ANOTHER POSSIBLE SCENARIO ON TUESDAY FOR LOCALIZED HEAVY RAIN IN THE ABSENCE OF BACKBUILDING CONVECTION WOULD BE WITH CONTINUED UPSTREAM CONVECTION RIDING OVER THE RIDGE AND MOVING OVER THE SAME AREAS UNDER WESTERLY FLOW. THE POTENTIAL FOR PRECIPITATION WILL DECREASE WEDNESDAY MORNING AS THE BOUNDARY CONTINUES SOUTH OF THE FORECAST AREA...AND THE INCREASING TREND IN TEMPERATURES WILL CONTINUE THROUGH THE REMAINDER OF THE PERIOD AS AS RIDGING PUMPS UP OVER THE EASTERN STATES AND A DEEP LOW CLOSES OFF OVER THE WEST. MAX TEMPERATURES ARE FORECAST TO RANGE FROM THE LOW TO MID 80S ACROSS THE REGION.
-- End Changed Discussion --
&& .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS THROUGH THE PERIOD. PATCHY CIRRUS MAY BE SEEN OVERNIGHT AND INTO SATURDAY...AND SOME SCATTERED FLAT CU ARE POSSIBLE DURING SATURDAY AFTERNOON. WINDS WILL GENERALLY REMAIN UNDER 10 KNOTS FROM THE NORTH AND NORTHWEST. .OUTLOOK.../SATURDAY THROUGH WEDNESDAY/... THE NEXT CHANCE FOR GENERAL RESTRICTIONS IS EXPECTED WITH TUESDAY FRONTAL ENCROACHMENT. && .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.