Area Forecast Discussion
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000 FXUS61 KPBZ 040732 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 332 AM EDT MON MAY 4 2015 .SYNOPSIS... WARM TEMPERATURES CONTINUE TODAY WITH DEPARTING HIGH PRESSURE. A SLOW-MOVING FRONTAL BOUNDARY BRINGS RAIN CHANCES TONIGHT AND INTO WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... ANOTHER QUIET NIGHT IS IN PROGRESS...WITH PATCHES OF CIRRUS FLOATING BY IN SOUTHWEST FLOW ALOFT. HOWEVER...FORECAST BEGINS TO BECOME MORE ACTIVE DURING THIS PERIOD. SURFACE HIGH WILL CONTINUE TO TRACK AWAY FROM THE CAROLINA COAST OVER THE NEXT 24 HOURS. H500 PATTERN HAS A SUMMER-LIKE FEEL TO IT...WITH OUR CWA ON THE OUTER PERIPHERY OF A STRONG RIDGE SOUTH OF THE MASON/DIXON LINE. EXPECT ANOTHER ROUND OF CU TO DEVELOP TODAY. THESE WILL HAVE MORE VERTICAL DEPTH AS COMPARED TO YESTERDAY AS THE H700 CAP WILL NOT BE PRESENT TODAY. WESTERLIES TRY TO SETTLE SOUTH LATER TODAY AND TONIGHT...WITH A FRONTAL BOUNDARY MAKING A PUSH. WHILE MODELS ARE IN GOOD AGREEMENT WITH THE LARGE-SCALE FIELDS...THERE IS UNCERTAINTY IN HOW FAR AND HOW QUICKLY THE FRONT MAKES SOUTHERLY PROGRESS. FOR NOW...NAM/GFS AND SREF POINT TO A 12Z TUESDAY POSITION IN THE CWA BUT NORTH OF PIT...AND WILL TAKE THIS SUGGESTION. PLACED LIKELY POPS NORTH OF A PHD/BTP/DUJ LINE DUE TO THIS THINKING...WITH CHANCE POPS TO THE SOUTH. ALTHOUGH THE FIRST RAINDROPS COULD ARRIVE PRIOR TO 00Z...MOST CONFIDENT IN SEEING ACTIVITY AFTER THAT TIME AS WE SHOULD ONCE AGAIN SEE DEEP MIXING AND A DRY BOUNDARY LAYER DURING THE AFTERNOON. MODELS HAVE REALLY STRUGGLED WITH DEWPOINTS THE LAST COUPLE OF DAYS...UNDERESTMATING THE DOWNWARD MIXING OF DRY AIR. WENT LIGHT ON THE THUNDER CHANCES THIS AFTERNOON/EVENING WITH UNIMPRESSIVE INSTABILITY NOTED ON MODEL SOUNDINGS. STILL LOOKS TOO WARM ALOFT TO SUPPORT DEEP CONVECTION. ONLY TWEAKED PREVIOUS HIGH TEMPERATURE FORECAST...AS IT WAS ALREADY WELL PLACED ON THE WARMER SIDE OF GUIDANCE. H850 TEMPS LOOK TO BE 1- 2C WARMER THAN YESTERDAY...AND WITH GOOD MIXING...THAT WOULD CORRESPOND TO HIGH TEMPERATURES 3-5 DEGREES WARMER THAN YESTERDAY IN MANY CASES. STUCK CLOSER TO MODEL CONSENSUS WITH LOW TEMPS TONIGHT WITH CONTINUED MIXING AND THICKENING CLOUDS. CL && .SHORT TERM /TUESDAY/... SURFACE HIGH PRESSURE OFF THE COAST WILL KEEP SOUTHWESTERLY WINDS ACROSS THE REGION THROUGH THE PERIOD...RESULTING IN CONTINUED WARM AIR ADVECTION. DAYTIME MAX TEMPERATURES WILL BE APPROXIMATELY 10 DEGREES ABOVE NORMAL. POPS INCREASE LATE MONDAY AS MOISTURE ADVECTION RAMPS UP OUT AHEAD OF A BOUNDARY SLOWLY TRANSITIONING SOUTH ACROSS THE FORECAST AREA. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... WARM TEMPERATURES WILL BE THE WEATHER HIGHLIGHT THROUGH THE EXTENDED PERIOD AS RIDGING REMAINS IN PLACE ACROSS THE EASTERN STATES. TEMPERATURES ARE EXPECTED TO RANGE BETWEEN 10 AND 15 DEGREES ABOVE THE AVERAGES. THE BEST CHANCE OF ANY PRECIPITATION STILL LOOKS TO BE TUESDAY INTO WEDNESDAY MORNING AS A FRONTAL BOUNDARY SLIDES OVER THE UPPER OHIO REGION. FORECAST SOUNDINGS SHOW MARGINAL INSTABILITY...BUT IMPROVED MOISTURE...MID LEVEL THERMAL TROUGHING...AND AFTERNOON WARMTH MAY SUPPORT SOME THUNDERSTORM DEVELOPMENT...WITH BETTER CHANCES OVER HIGHER TERRAIN. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... MAINTAINING VFR FORECAST FOR THE NEXT 24 HOURS...ALTHOUGH SOME ISSUES START TO CROP UP TOWARDS 06Z TUESDAY AND BEYOND. TODAY WILL ONCE AGAIN FEATURE DEEP MIXING...WITH HIGH-BASED CU DURING THE AFTERNOON. WINDS WILL BE A BIT STRONGER AS COMPARED TO YESTERDAY...WITH GUSTS OF 17-22 KNOTS OUT OF THE SOUTHWEST EXPECTED THIS AFTERNOON. MID AND UPPER CLOUDS WILL BEGIN TO THICKEN DURING THE LATE AFTERNOON AND EVENING HOURS AHEAD OF AN APPROACHING COLD FRONT. THE FIRST SHRA SHOULD ARRIVE AT FKL...AND POSSIBLY DUJ...PRIOR TO 06Z. .OUTLOOK.../TUESDAY THROUGH THURSDAY/... RESTRICTIONS ARISING FROM A FRONTAL INCURSION FROM THE NORTH ARE EXPECTED FROM LATE TONIGHT INTO TUESDAY NIGHT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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