Area Forecast Discussion
Issued by NWS

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KPBZ 232216 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 616 PM EDT TUE SEP 23 2014 .SYNOPSIS... DRY WEATHER CAN BE EXPECTED FOR THE REMAINDER OF THE WEEK AND TEMPERATURES WILL GRADUALLY WARM. && .NEAR TERM /THROUGH WEDNESDAY/... ONLY CHANGES NEEDED FOR THE EARLY EVE UPDATE WERE SOME DOWNWARD TWEAKS TO OVRNGT LOWS BASED ON THE LATEST DEWPOINT AND GUIDANCE TRENDS. OTHERWISE...SFC HIPRES CNTRD IN ERN OH WILL DVLP NEWD AS AN UPR TROF OVER THE COASTAL SERN CONUS CUTS OFF AND BUILDS NWD SLOWLY THRU WED NGT. AT THE SAME TIME...UPR RDG OVER THE NRN PLNS WILL AMPLIFY. SERN CONUS TROF WILL MOVE NWD ALONG THE APLCNS ON WED AS ASSOCIATED COASTAL LOPRES DVLPS TWD THE CHSPK BAY. CI ASSOCIATED WITH THIS TROF WILL BGN TO SPREAD NWWD ACRS FCST AREA ON WED MRNG. PCPN IS NOT XPCD TO REACH THE FCST AREA AS STRONG UPR RDG TO W SHOULD BE SUFFICIENT TO PREVENT WWD MVMT OF UPR LOW. RISING HTS/WARM ADVCNT WL SPPRT AN INCR IN TEMPS FOR WED TO SLGTLY ABV CLIMO AMID DPR MIXING AND STRONG MRNG SUNSHINE. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... MODEL GUIDANCE IS SOMEWHAT SPLIT ON THE TRACK OF A MID-LEVEL LOW UP THE EAST COAST GOING INTO THURSDAY. MOST DOMESTIC GUIDANCE KEEPS THE MAJORITY OF THE HEIGHT FALLS AND MOISTURE TO OUR EAST...WHILE THE ECMWF WRAPS ATLANTIC MOISTURE A TAD FARTHER WEST...AND THE CANADIAN WRAPS IT ALL THE WAY BACK INTO OUR FORECAST AREA. THIS IS A MANIFESTATION OF A WEAKENING OF THE MID- LEVEL RIDGE OVER THE CENTRAL GREAT LAKES FROM WEDNESDAY AFTERNOON INTO THURSDAY ON ALL THE MODELS...HOWEVER A TRACKING OF THE SYSTEM UP THE COAST DIRECTLY INTO THIS WEAKENING RIDGING SEEMS A BIT FAR- FETCHED. AS SUCH...THE DOMESTIC PREPONDERANCE OF GUIDANCE WAS FOLLOWED MORE CLOSELY...WHICH MAINTAINS A DRY FORECAST THROUGH THURSDAY WITH ONLY NOMINAL INCREASES IN SKY COVER ALONG THE EASTERN PERIPHERY OF THE FORECAST AREA. IT WOULD SEEM LATER MODEL CYCLES WILL BE LIKELY TO FOCUS IN ON A MORE WELL CLUSTERED SOLUTION OVER THE NEXT FEW CYCLES...BUT FOR THE MOMENT...IT WOULD SEEM THE MOST PRUDENT FORECAST IS CONTINUITY. BY THURSDAY NIGHT AND FRIDAY...WHATEVER TRACK THAT MID-LEVEL SYSTEM TAKES QUICKLY BECOMES IRRELEVANT AS THE PREPONDERANCE OF GUIDANCE HAS WEAKENED IT AND ABSORBED IT INTO THE POLAR JET FLOW WELL TO OUR NORTH. THIS ALLOWS FOR STRONG RIDGING TO OVER-ARCH A WEAK MID-LEVEL LOW IN THE CENTRAL PLAINS...BRINGING A STRONG MID- LEVEL RIDGE FROM THE FOUR CORNERS TO THE RED RIVER VALLEY OF ND/MN...TOWARD LAKE ONTARIO. THIS MEANS ABUNDANT WARM AIR ALOFT AND STRONG STABILIZATION. AS SUCH...THE CHANCE OF RAINFALL LOOKS TO BE ESSENTIALLY ZERO...AND EVEN CLOUDS WILL BE DIFFICULT TO MUSTER AS THE LAPSE RATES WILL BE SO UNFAVORABLE IN A VERY DRY COLUMN. ADDITIONALLY...GIVEN THAT WE WILL BE ON THE DOWNSTREAM SIDE OF THE RIDGE...DEWPOINTS SEEM UNLIKELY TO JUMP UP TOO QUICKLY WITH VERY LIGHT EAST/NORTHEAST FLOW IN THE LOW LEVELS LIKELY TO CONTINUE. THIS MEANS A GRADUAL WARM UP WITH LOW HUMIDITY SEEMS LIKELY. WHILE 500 MB HEIGHT VALUES WILL BE IMPRESSIVE...A LACK OF VERTICAL MIXING AND STRONG STABILITY WILL KEEP 850 MB TEMPERATURE VALUES FROM BEING REALIZED DRY ADIABATICALLY AT THE SURFACE...EVEN WITH THE DRY COLUMN. AS SUCH...WHILE THE +13 TO +15C THAT CAN BE NOTED ON MOST MODELS BY LATE IN THE WEEK IS IMPRESSIVE AT 850 MB FOR SEPTEMBER...MID TO A FEW UPPER 70S SEEM MORE LIKELY THAN THE 80S THAT WILL BE MORE LIKELY OVER THE UPPER MIDWEST ON THE UPSTREAM SIDE OF THE SURFACE HIGH...WHERE MIXING WILL BE MUCH MORE EFFICIENT. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... TEMPERATURES WILL HOVER BETWEEN 5 TO 10 DEGREES ABOVE NORMAL INTO EARLY NEXT WEEK AS A LARGE RIDGE OF HIGH PRESSURE TRANSITIONS ACROSS THE REGION. && .AVIATION /22Z TUESDAY THROUGH SUNDAY/... VF AND LGT SFC WIND CAN BE EXPECTED INTO THE PRE DAWN HRS...WHEN IFR VSBY RESTRICTIONS BECOME LKLY AT MOST TERMINALS OWING TO VALLEY FOG. THE SHALLOW FOG WILL LIFT BY 13-14 UTC. OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/... HIGH PRES WL MAINTAIN GENL VFR THROUGH THE WEEKEND. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ 15

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