Area Forecast Discussion
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000 FXUS61 KPBZ 170809 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 409 AM EDT WED SEP 17 2014 .SYNOPSIS... DRY AND SEASONABLE COOL CONDITIONS CAN BE EXPECTED INTO FRIDAY. && .NEAR TERM /THROUGH THURSDAY/... LOW LEVEL CLOUD COVERAGE THAT HAS DEVELOPED OVER THE PAST COUPLE HOURS HAS LIMITED TEMPERATURE FALLS OVERNIGHT...WHILE LATEST GUIDANCE GIVES INDICATION THAT SCATTERED TO BROKEN CLOUD COVERAGE BETWEEN 3-5KFT SHOULD PERSIST UNTIL AFTER SUNRISE. WITH THAT...STILL EXPECT A FAIR AMOUNT OF FOG DEVELOPMENT AS DEWPOINT DEPRESSIONS ARE MINIMAL BUT WIDESPREAD DENSE FOG IS NOT LIKELY AND ADVISORIES WILL NOT BE NEEDED. SCATTERED SHALLOW CUMULUS WILL DEVELOP TOMORROW AS THERE IS ENOUGH MOISTURE TRAPPED UNDER A STRONG SUBSIDENCE INVERSION AT 5KFT. WITH HIGH PRESSURE BUILDING IN AND LIMITED MIXING ALOFT...TEMPERATURES WILL REMAIN SLIGHTLY BELOW NORMAL. TOMORROW NIGHTS MINIMUM TEMPERATURES WILL BE SIMILAR TO THOSE OBSERVED TONIGHT AND WHILE THERE WILL BE PATCHES OF FOG THAT DEVELOP...THE EXTENT WILL BE LESS THAN WHAT HAS RECENTLY BEEN OBSERVED DURING THE MORNINGS. && .SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/... SFC HIGH MOVES SOUTHEAST ACROSS THE GREAT LAKES THURS INTO FRI...REINFORCING THE COOL AND DRY CONDITIONS. BY FRI AFTERNOON THE CENTER OF THE HIGH SHIFTS FAR ENOUGH EAST TO ALLOW SOUTHEASTERLY FLOW IN THE LOW LEVELS. THIS ADVECTS WARMER TEMPS INTO THE AREA...ALONG WITH A ATLANTIC MOISTURE MOVING FROM THE PIEDMONT OF VA/NC INTO THE ERN SLOPES OF THE APPALACHIANS. WHILE THE 00Z NAM IS BULLISH ON THE LLVL MOISTURE ADVECTION TO THE POINT OF QPF GENERATION OVER OUR RIDGES...DRY AIR JUST ABOVE THE SFC AS WELL AS COPIOUS DRY AIR ALOFT SHOULD PRECLUDE SHOWERS. AS THE HIGH PUSHES FURTHER OFF THE ATLANTIC SEABOARD FRI NIGHT...LLVL SOUTHERLY FLOW INCREASES. WAA BRINGS H85 TEMPS IN THE 12-14C RANGE SAT WITH PLENTY OF MIXING AND MOSTLY SUNNY SKIES. THIS ALL RESULTS IN WHAT SHOULD BE ONE OF THE WARMEST DAYS IN THE LAST WEEK OR TWO. DAYTIME HIGHS SHOULD TOP OUT IN THE MID TO UPPER 70S ACROSS THE LOWER TERRAIN...LOWER 70S IN THE HIGH TERRAIN AND NRN ZONES. TAX && .LONG TERM /SUNDAY THROUGH TUESDAY/... TEMPERATURES REMAIN AT OR SLIGHTLY ABOVE AVERAGE INTO SUNDAY WITH A COLD FRONT JUST WEST OF THE AREA. MODELS CONTINUE TO SLOW DOWN THE FROPA SUN NIGHT ALLOWING...KEEPING US IN THE WARM SECTOR WITH SOUTHERLY FLOW. TIMING AND RELATIVELY WARM MID-LEVELS LOOK TO MINIMIZE INSTABILITY AHEAD AND ALONG THE FRONT...SO KEEPING MENTION OF THUNDER OUT OF FORECAST FOR NOW. THE INFLUENCE OF THE UPPER TROUGH MON WILL KEEP POPS IN THE FORECAST BEFORE YET ANOTHER COOL AND DRY CANADIAN AIR MASS MOVES IN FOR MID-WEEK. TAX && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... AREAS OF SCATTERED TO BROKEN CLOUD COVERAGE THAT HAS DEVELOPED WILL LIMIT OVERALL FOG FORMATION OVERNIGHT IN GENERAL...HOWEVER...IFR FOG WILL STILL BE POSSIBLE AT TERMINALS BY DAYBREAK THIS MORNING. PARTICULARLY IN THE VALLEYS AND OVER AREAS WHERE CLOUDS WERE LIMITED OVERNIGHT. FOG WILL BURN OFF BY 14-15Z...LEAVING SCATTERED SHALLOW CUMULUS AROUND 5KFT AGL. OUTLOOK...WEDNESDAY THROUGH SUNDAY... OUTSIDE OF THE POSSIBILITY OF VALLEY FOG ONE OR TWO MORNINGS...VFR CONDITIONS ARE EXPECTED THROUGH THE WEEK. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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