Area Forecast Discussion
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000 FXUS61 KPBZ 190809 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 409 AM EDT SUN APR 19 2015 .SYNOPSIS... A DRY BEGINNING TO THE DAY...BUT SHOWERS WILL OVERSPREAD THE REGION THIS AFTERNOON AND CONTINUE THROUGH MONDAY. UNSEASONABLY COOL TEMPERATURES ARE EXPECTED FOR THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LOW PRESSURE ADVANCING OUT OF THE LOWER MISSISSIPPI VALLEY WILL SPREAD CLOUDS AND EVENTUALLY SHOWERS OVER THE REGION. WITH CLOUDS AND RAIN...TEMPERATURES WILL HOLD CLOSER TO THE SEASONAL AVERAGES. INCREASING PRECIP CHANCES TO CATEGORICAL NUMBERS BY THIS EVENING WERE MAINTAINED WITH JUST SOME MINOR ADJUSTMENTS IN TIMING. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY/... SHOWER COVERAGE WILL DECREASE OVERNIGHT AS UPPER LEVEL SUPPORT SHIFTS TO THE EAST AND A LARGE UPPER LEVEL DRY SLOT OVERSPREADS THE AREA. THE RESULTING SUBSIDENCE IS EXPECTED TO CONTINUE THROUGH MONDAY MORNING...AND MAY PROMOTE MODEST HEATING OF A RELATIVELY-MOIST BOUNDARY LAYER WITH 45-50KT OF SOUTHWEST FLOW ALOFT. A SECOND SHORTWAVE TROUGH IS PROJECTED TO MOVE QUICKLY NORTHEASTWARD AND CROSS THE REGION BY LATE DAY. LIFT IN ASSOCIATION WITH THAT DISTURBANCE WOULD AID CONVECTIVE DEVELOPMENT DURING THE AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED WITH THIS SCENARIO. WIDESPREAD SEVERE THUNDERSTORMS ARE NOT EXPECTED OWING TO PROGNOSIS OF WEAK MID LEVEL LAPSE RATES. UNUSUALLY STRONG UPPER LOW PRESSURE IS FORECAST TO BUILD SEWD INTO THE GREAT LAKES REGION BY TUESDAY...WITH ITS ASSOCIATED COLD FRONT TO CROSS THE FORECAST AREA DURING THE MORNING. COLD ADVECTION BEHIND THE FRONTAL PASSAGE IS PROGGED TO PROVIDE INCREASED COVERAGE OF STRATOCU AND POSSIBLE LAKE ENHANCEMENT TO LIGHT PRECIPITATION...WITH THAT LIMITED TO THE NORTHERN ZONES WITH EXPECTATIONS OF WESTERLY FETCH AND DRY ADVECTION. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... BROAD UPPER TROUGHING WILL REMAIN OVER THE EASTERN CONUS THROUGH THE EXTENDED AND RESULT IN BELOW NORMAL TEMPERATURES EACH DAY ALONG WITH CLOUDY SKIES AND SLIGHT CHANCES FOR PRECIPITATION THROUGHOUT THE PERIOD AS SHORTWAVES TRANSITION THROUGH THE FLOW AND CAA ALOFT PERSISTS. CONFIDENCE IS HIGH IN THE GENERAL FORECAST AS MODELS HAVE BEEN FAIRLY CONSISTENT IN PROGGING THIS LONGWAVE PATTERN...REFLECTED IN LATEST RMOP AND MODTRENDS GUIDANCE. HOWEVER...CONFIDENCE IN TIMING OF ANY MORE SIGNIFICANT PERIODS OF PRECIPITATION IS RELATIVELY LOW. FORECAST MAX/MIN TEMPERATURES ARE NOT EXCEPTIONALLY COLD...BUT PERSISTENT AROUND 10 DEGREES BELOW NORMALS AS ENSEMBLE ANOMALIES ARE SHOWING TEMPS AND HEIGHTS ALOFT ONLY RANGING FROM 1-2 STANDARD DEVIATIONS BELOW NORMAL THROUGH THE PERIOD. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... POTENTIAL LLWS CONDITIONS UNTIL GUSTY SOUTHEASTERLY WINDS MIX DOWN TO THE SURFACE AHEAD OF AN APPROACHING WARM FRONT LATER THIS MORNING. NO RESTRICTIONS ARE ANTICIPATED UNTIL RAIN SHOWERS ASSOCIATED WITH THE WARM FRONT DEVELOP LATE THIS AFTERNOON. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... PERIODIC RESTRICTIONS ARE EXPECTED THROUGH MONDAY NIGHT AS LOW PRESSURE CROSSES THE REGION. RESTRICTIONS ARE POSSIBLE WITH A MID WEEK UPPER TROUGH. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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