Area Forecast Discussion
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPBZ 261052 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 652 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/...
-- Changed Discussion --
LATEST RADAR SHOWS SCATTERED SHOWERS SPREADING ACROSS THE FORECAST AREA WITH GREATER COVERAGE STILL TO THE WEST AND ALIGNED WELL WITH A BAND OF 850MB FRONTOGENESIS. WITH THAT...NO MAJOR CHANGES LOOK NEEDED AT THIS POINT AS LATEST MODEL PROGS OF THIS FEATURE LINE UP WELL WITH THE ONGOING FORECAST. ONLY MINOR CHANGES WERE MADE TO BETTER ALIGN TEMPERATURES WITH OBS TRENDS AND ALSO INCLUDE MENTION OF ISOLATED THUNDERSTORMS ACROSS EASTERN OHIO ZONES EARLIER THAN PREVIOUSLY FORECAST. PREVIOUS DISCUSSION FOLLOWS.. 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.
-- End Changed Discussion --
&& .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 /12Z 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. && $$

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.