Area Forecast Discussion
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000 FXUS61 KPBZ 012124 AAA AFDPBZ AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PITTSBURGH PA 524 PM EDT WED APR 1 2015 .SYNOPSIS... DRY WEATHER TONIGHT WILL BE FOLLOWED BY A WARM THURSDAY WITH INCREASING SHOWER AND THUNDERSTORM CHANCES. && .NEAR TERM /THROUGH THURSDAY/...
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530PM UPDATE...SKIES HAVE JUST ABOUT CLEARED AS THE FLOW HAS VEERED TO THE WEST AND THE COLD AIR ALOFT IS BEING EJECTED TO THE NORTHEAST. SKY COVERAGE HAS BEEN ADJUSTED AS WELL AS OVERNIGHT TEMPS. PREVIOUS DISCUSSION... SHORTWAVE IS IN THE PROCESS OF EXITING TO THE EAST AT PRESENT. WHAT WAS A MORE SOLID DECK OF STRATUS/STRATOCU HAS LIFTED AND BROKEN UP INTO MAINLY HIGH CU OR LOW AC. THESE CLOUDS WILL MOVE OUT/BREAK UP DURING THE LATE AFTERNOON AND EARLY EVENING...LEADING TO A MOSTLY CLEAR OVERNIGHT PERIOD AS H500 RIDGE AXIS ARRIVES BY 12Z. WITH SURFACE HIGH MOVING OFF TO THE EAST...SURFACE PRESSURE GRADIENT STARTS TO TIGHTEN UP AFTER MIDNIGHT. THIS WILL HELP TO KEEP THE BOUNDARY LAYER STIRRED AND KEEP TEMPERATURES FROM FALLING OFF TOO FAR. TRIED TO LEAN AT OR A TOUCH ABOVE THE MODEL CONSENSUS FOR LOW TEMPS. SOUTHERLY FLOW AND WARM ADVECTION INCREASE ON THURSDAY WITH H850 TEMPS CLIMBING TO +9/+10 DURING THE AFTERNOON. THIS WILL HELP DRIVE TEMPERATURES AROUND 15 DEGREES ABOVE NORMAL...AND HAVE HIGH TEMPS NEAR THE TOP END OF GUIDANCE. PIT HAS A CHANCE TO REACH 70 DEGREES FOR THE FIRST TIME SINCE LAST NOVEMBER 11. THIS IS IN ADVANCE OF THE NEXT MAJOR WEATHER SYSTEM...WITH A FRONTAL BOUNDARY EXTENDING ACROSS THE GREAT LAKES INTO THE MISSISSIPPI VALLEY FROM A CANADIAN LOW. EXPECTING THE BULK OF THE PRECIPITATION TO ARRIVE TOWARDS AND AFTER SUNSET FROM THE WEST...AND DO HAVE LIKELY POPS HERE BY 00Z. HOWEVER...SOME MEAGER INSTABILITY AND ISENTROPIC LIFT MAY POP SOME SHRA FROM LATE MORNING ON. ENOUGH INSTABILITY FOR A FEW THUNDERSTORMS AS WELL...BUT NOT ENOUGH FOR A SEVERE WEATHER CONCERN. DESPITE THE STRONG SOUTHERLY FLOW...MODEL SOUNDINGS ARE NOT SUGGESTING VERY DEEP MIXING...WHICH WOULD KEEP 50+ KNOT H850 WINDS LOCKED UP ALOFT. DO EXPECT SOME 25-30 KNOT GUSTS AT THE SURFACE BUT NOT ENOUGH FOR A WIND ADVISORY. QPF THROUGH 00Z SHOULD REMAIN BELOW A QUARTER INCH IN GENERAL...WITH THE MORE SIGNIFICANT RAIN TO FOLLOW.
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