Area Forecast Discussion
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000 FXUS61 KPBZ 261408 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 1008 AM EDT THU MAR 26 2015 .SYNOPSIS... SHOWERS EXPECTED TODAY WITH A CHANCE OF THUNDERSTORMS DURING THE LATE MORNING AND AFTERNOON AS LOW PRESSURE CROSSES THE REGION. MUCH COLDER WEATHER WILL FOLLOW THROUGH THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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MAIN CHANGE WAS TO INCREASE WIND GUSTS ACROSS THE EAST TODAY...PARTICULARLY ALONG THE SOUTHEAST RIDGES. VWP/MORNING SOUNDINGS SHOW 40-50 KNOT WINDS JUST A FEW THOUSAND FEET OFF THE GROUND. AREAS LIKE MGW AND LBE WILL LIKELY ABLE TO MIX SOME OF THAT WIND DOWN WITH AT LEAST A LITTLE SUN BEFORE THE MAIN FRONTAL PRECIP ARRIVES...AND HAVE ADDED 25-35 KNOT GUSTS TO THE AREA. SHOULD BE ENOUGH INSTABILITY FOR A FEW THINK ANY SCATTERED CONVECTION WILL NOT BE ABLE TO BRING STRONGER/SEVERE GUSTS TO THE GROUND AT THIS TIME BUT WILL MONITOR. MOST OTHER CHANGES WERE MAINLY MINOR...BUT DID REDUCE POPS IN THE SOUTHEAST FOR A FEW HOURS IN THE WARM SECTOR. DID NOT CHANGE OVER FKL TO SNOW PRIOR TO 00Z FOR NOW BUT THIS REMAINS POSSIBLE DEPENDING ON HOW QUICKLY COLDER AIR CAN MOVE IN. STILL THINK FRONT CLEARS CWA BY 21Z OR SO. PREVIOUS DISCUSSION... AS THE LONGWAVE PATTERN AMPLIFIES ACROSS THE EASTERN STATES A COLD FRONT WILL SLOWLY TRANSITION ACROSS THE REGION TODAY WITH THE FRONTAL BOUNDARY EAST OF THE FORECAST AREA BY EARLY THIS EVENING. THERE IS SLIGHT CHANCE OF THUNDERSTORM DEVELOPMENT SOUTH OF INTERSTATE 70 LATE THIS MORNING THROUGH MID AFTERNOON WITH SURFACE DEWPOINTS PUSHING OVER 50F AND MODEL SOUNDINGS SHOWING A THIN BUT POSITIVE CAPE PROFILE. SREF MEAN VALUES ARE LOW BUT PRESENT AROUND 50 J/KG AS FAR NORTH AS PITTSBURGH BUT FURTHER SOUTH TOWARDS MORGANTOWN MEAN VALUES INCREASE TO BETWEEN 300-400. EASTERN COUNTIES WITH FRONTAL PASSAGE LATER IN THE DAY WILL ALSO BE MORE UNSTABLE WITH MORE TIME TO WARM UP IN THE STRONG WARM AIR ADVECTION AHEAD OF THE FRONT. EXPECT ANY DEVELOPMENT TO BE CONFINED TO ALONG THE FRONT IN THE ABSENCE OF ANY OTHER TRIGGER...WITH MAIN POTENTIAL IMPACT BEING STRONG WIND GUSTS WITH LAPSE RATES RANGING FROM 8-10 C/KM IN THE LOWER LEVELS AND A FAIR AMOUNT LOW LEVEL SHEAR. PRECIPITABLE WATER VALUES ARE RESPECTABLE...BETWEEN ONE AND TWO STANDARD DEVIATIONS ABOVE CLIMATOLOGICAL NORMS...AND WITH THE AREA UNDER THE RIGHT ENTRANCE REGION OF A JET MAX...INCREASED LIFT ASSOCIATED WITH THE DEEPENING SURFACE LOW...AND POTENTIAL FOR MORE CONVECTIVE PRECIPITATION...THE FORECAST AREA SHOULD SEE AROUND A HALF INCH OF QPF IN GENERAL. THE SURFACE LOW WILL TRACK ALONG THE SOUTHERN OHIO BORDER AND UP ACROSS CENTRAL PA...WITH THE GREATEST QPF AMOUNTS EXPECTED ALONG AND JUST NORTH OF THIS TRACK...UP TO THREE QUARTERS OF AN INCH ACROSS NORTHERN ZONES DOWN TO BELOW ONE HALF INCH ACROSS THE SOUTH. EXPECTING A NON-DIURNAL TEMPERATURE TRACE ESPECIALLY IN THE WEST...WITH MUCH ABOVE NORMAL TEMPERATURES ESPECIALLY IN THE SOUTHEAST COUNTIES....FALLING RAPIDLY AFTER FRONTAL PASSAGE.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... PRECIP COVERAGE WILL DECREASE QUICKLY BEHIND THE FRONT AS THE COLDER AIR RUSHES IN AND SUPPORT WAVERS...WITH ANY REMAINING PRECIPITATION CHANGING OVER TO SNOW FROM NORTHWEST TO SOUTHEAST WITH TIME AS SUBZERO 850 MB AIR LAGS THE FRONT A BIT. GIVEN THE TIME OF YEAR AND RELATIVELY WARM GROUND...NOT EXPECTING MUCH SNOW ACCUMULATION. SHOWERS WILL REDEVELOP ON FRIDAY AS THE UPPER SHORTWAVE TROUGH ROTATES SOUTHEAST ACROSS THE GREAT LAKES. MOISTURE WILL BE SHALLOW AND LIMITED AND EVEN THOUGH TEMPERATURES WILL BE WELL BELOW NORMAL UNDER COLD AIR ADVECTION THROUGHOUT THE DAY...THE BOUNDARY LAYER LOOKS TO BE WARM ENOUGH TO WHERE WE WILL SEE A MIX OR CHANGEOVER TO RAIN IN MANY AREAS BEFORE CHANGING BACK TO SNOW FRIDAY NIGHT. PRECIPITATION WILL TAPER OFF BY MIDDAY SATURDAY AS H850 THERMAL TROUGH BEGINS TO LIFT OUT. TEMPERATURES WILL REMAIN WELL BELOW NORMAL ON SATURDAY. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... COLD HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH SUNDAY WITH A MODERATION IN TEMPS DURING THE AFTERNOON. THE NEXT SYSTEM WILL QUICKLY MOVE THROUGH THE GREAT LAKES SUNDAY NIGHT...BRINGING THE RISK FOR RAIN OR SNOW AND ANOTHER SHOT OF COLD AIR ON MONDAY. DRY WEATHER AND A SLOW MODERATION IN TEMPS IS EXPECTED TUESDAY AND WEDNESDAY. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... CONDITION DETERIORATION IS EXPECTED LATE TONIGHT WITH THE ADVANCE OF LOW PRESSURE. MVFR CEILING DEVELOPMENT WILL DEGRADE TO IFR IN SHOWERS DURING THE AROUND DAWN AND INTO THE AFTERNOON HOURS. IMPROVEMENT IS NOT ANTICIPATED UNTIL AFTER THE COLD FRONT PASSAGE LATE IN THE DAY. .OUTLOOK.../THURSDAY NIGHT THROUGH MONDAY/... RESTRICTIONS ARE POSSIBLE INTO SATURDAY AS COLD ADVECTION CONTINUES IN THE WAKE OF THE FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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