Area Forecast Discussion
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000 FXUS61 KPBZ 041630 AAC AFDPBZ AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PITTSBURGH PA 1230 PM EDT TUE AUG 4 2015 .SYNOPSIS... GENERALLY DRY AND SUNNY CONDITIONS ARE EXPECTED THROUGH WEDNESDAY. RAIN CHANCES INCREASE ON THURSDAY AS AN UPPER-LEVEL DISTURBANCE APPROACHES THE REGION. && .NEAR TERM /THROUGH WEDNESDAY/... A TROUGH AT H5 WILL LINGER OVER ERN CANADA TODAY...MAINTAINING GENERAL WLY FLOW ALOFT IN THE GREAT LAKES REGION. HIGH PRESSURE AT THE SURFACE WILL BUILD EWD FROM INDIANA/OHIO AND WILL AID IN DRYING THE LOW LEVELS FOR MOST OF THE FORECAST AREA AND MOSTLY SUNNY-PARTLY CLOUDY CONDITIONS FOR THE DAY. THE PRIMARY EXCEPTION WILL BE IN THE NRN ZONES...WHERE A SECONDARY FRONTAL SURGE OVERNIGHT WILL BE PRECEDED BY A PLUME OF ENHANCED LOW-LEVEL MOISTURE...EVIDENT THIS AFTERNOON BY THE MORE ROBUST CU FIELD PRESENT. IN THIS AREA...MODELS INDICATE EXISTENCE OF MODEST INSTABILITY AND GENERATE LIGHT PRECIPITATION. WITH THE THREE INGREDIENTS FOR CONVECTION PRESENT...POPS WERE INCREASED TO CHANCE CATEGORY OVERNIGHT AS THE FRONTAL SURGE TRANSLATES SEWD. AMID CONTINUED HIGH PRESSURE...WEDNESDAY WILL FEATURE CONSIDERABLE SUN IN THE MORNING...GIVING WAY TO PARTLY CLOUDY CONDITIONS AS COLD AIR ADVECTION AND STRONG HEATING YIELD A BROAD STRATOCU FIELD. DRY AIR AND HIGH PRESSURE JUSTIFY ELIMINATING POPS ALMOST EVERYWHERE WEDNESDAY AND WEDNESDAY NIGHT. MAXIMA WILL BE SLIGHTLY BELOW NORMAL WITH THE PRESENCE OF THE UNSEASONABLY COOL UPPER TROUGH...AND MINIMA ALSO BELOW NORMAL OWING TO DRY AIR AND GENERALLY EFFICIENT RADIATIONAL COOLING. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/... DEEP SHORTWAVE TROUGH WILL DIG INTO THE MIDWEST THURSDAY MORNING. A SURFACE LOW WILL ACCOMPANY THE UPPER-LEVEL SYSTEM AND MOVE ACROSS MISSOURI INTO ILLINOIS. THE EASTWARD MOVEMENT OF THE SYSTEM HAS SLOWED FROM PREVIOUS RUNS...SO SHOWERS FROM THIS SYSTEM WILL HOLD OFF UNTIL LATER IN THE DAY. MODELS STILL WRANGLING WITH THE TRACK OF THE SURFACE LOW...STRENGTH OF THE UPPER-LEVEL WAVE...AND IN TURN THE TIMING AND LOCATION OF SHOWERS. MODELS ARE IN MODERATE AGREEMENT THAT THE SOUTHERN HALF OF THE AREA WILL SEE THE BEST CHANCE FOR RAIN. THE MOST UNSTABLE ATMOSPHERE REMAINS TO THE SOUTH OF THE SURFACE LOW...SO DO NOT EXPECT CONVECTION TO DEVELOP. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... MODELS STILL TRYING TO DETERMINE A SOLUTION FOR A SURFACE WAVE WHICH WILL MOVE OUT OF THE MIDWEST AND CROSS THE MID-ATLANTIC LATE THIS WEEK AND INTO THE FIRST HALF OF THE WEEKEND. AFTER THIS POINT...A LOW CONFIDENCE FORECAST DUE TO MODEL DISCREPANCIES IN TIMING OF SHORTWAVES IN THE NORTHWEST FLOW ALOFT. && .AVIATION /05Z TUESDAY THROUGH SATURDAY/... HIGH PRESSURE AT THE SURFACE WILL CONTINUE THE DRYING TREND CURRENTLY OBSERVED AT ALL TERMINALS...LEADING TO A VFR FCST FOR ALL TAFS. AMID DEEP MIXING...WNWLY WIND WILL INCREASE AND BECOME GUSTY TO 15-20 KT THIS AFTERNOON. A PLUME OF MOISTURE AHEAD OF A SECONDARY FRONTAL SURGE MAY GENERATE SHOWERS AT KFKL/KDUJ OVERNIGHT TONIGHT...BUT VFR CONDITIONS OTHERWISE ARE EXPECTED TO PERSIST THROUGH WEDNESDAY NIGHT AT ALL TERMINALS. OUTLOOK...THURSDAY THROUGH FRIDAY... THE NEXT CHANCE FOR RESTRICTIONS IS EXPECTED WITH A THURSDAY UPPER DISTURBANCE. && .EQUIPMENT... KPBZ RADAR REMAINS DOWN. TECHNICIANS ADVISE THAT A RETURN TO SERVICE IS EXPECTED LATE THIS AFTERNOON. GREGS KNOB NOAA WEATHER RADIO IS OFF THE AIR WITH A FAILED TRANSMITTER. RESTORATION IS EXPECTED WITHIN 24 HOURS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ UPDATE...KRAMAR

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