Area Forecast Discussion
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000 FXUS61 KPBZ 050129 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 929 PM EDT SAT JUL 4 2015 .SYNOPSIS... HIGH PRESSURE PROVIDES DRY WEATHER AND SEASONABLE TEMPERATURES SUNDAY. RAIN CHANCES RETURN MONDAY WITH AN UPPER DISTURBANCE...AND CONTINUE INTO WEDNESDAY WITH AN APPROACHING FRONT. && .NEAR TERM /THROUGH SUNDAY/...
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DRIER AIR HAS MADE SOME INROADS INTO THE CWA THIS EVENING...HOWEVER DEWPOINTS ALONG THE RIDGES...IN THE SOUTHERN TIER OF THE CWA...AND IN MOST OF OHIO FAILED TO DROP BELOW 60F. THIS COULD BE PROBLEMATIC GOING INTO TONIGHT AS MOSTLY CLEAR SKIES DOMINATE THE REGION AND RADIATION FOG STARTS TO BECOME POSSIBLE. THERE ARE A FEW PROBLEMS WITH THIS THEORY...HOWEVER...AS AFTERNOON VISIBLE IMAGERY REVEALED ABUNDANT HIGH LEVEL SMOKE FROM UPSTREAM WILDFIRES MAKING ITS WAY INTO THE AREA. THIS SMOKE IS GENERALLY OPAQUE TO OUTGOING LONGWAVE RADIATION...SO IT MAY ACTUALLY WORK TO HOLD TEMPERATURES UP A BIT MORE THAN WOULD HAVE OTHERWISE BEEN THE CASE. THIS WOULD WORK AGAINST WIDESPREAD FOG FORMATION. THAT SAID...DECOUPLING SEEMS TO HAVE ALREADY OCCURRED...AND GIVEN OUR RECENT PROPENSITY FOR FOG AND OUR RECENT RAIN ALLOWING FOR ABUNDANT SOIL MOISTURE WHICH WILL ALLOW FOR UPWARD MOISTURE FLUX OVERNIGHT...IT WOULD SEEM SOME FOG IS POSSIBLE. IT HAS BEEN ADDED TO THE GRIDS...AND WILL LIKELY DEVELOP BY SUNRISE AND DISSIPATE FAIRLY QUICKLY AFTER SUNRISE. FRIES PREVIOUS DISCUSSION FOLLOWS...THE HIGH SLOWLY SLIDES EAST SUNDAY. MOST LOCATIONS WILL ENJOY A MOSTLY SUNNY DAY. HOWEVER...SOUTHEAST FLOW WILL PROMOTE A MOISTURE INCREASE NEAR THE RIDGES IN THE SOUTHEAST CWA. SOUNDINGS SHOW SOME MODEST INSTABILITY DURING THE AFTERNOON AS WELL. CANNOT RULE OUT AN ISOLATED DIURNAL SHRA HERE AND HAVE INCLUDED THIS POSSIBILITY IN THE HIGHER ELEVATIONS OF WV AND MD. DROPPED LOW TEMPS A COUPLE DEGREES TONIGHT GIVEN THE CLEARING SKIES...LIGHT WIND...AND LOWERING DEWPOINTS. READINGS RECOVER TOWARDS SEASONABLE LEVELS SUNDAY AFTERNOON WITH WARMER H850 AIR AND SLIGHTLY MORE EFFICIENT MIXING.
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&& .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
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DRY...AND WARMER WEATHER IS THEN EXPECTED AS HIGH PRESSURE BUILDS THROUGH SUNDAY. SUNDAY NIGHT AND MONDAY ANOTHER DISTURBANCE IS NOW PROJECTED TO BRING CHANCE OF PRECIPITATION TO OUR SOUTHERN CWA OF WV AND MD. WILL KEEP CURRENT FORECAST OF INCREASING CHANCE WITH THE TUESDAY FRONTAL SYSTEM ALL AREAS AND TEMPERATURES READINGS AT OR SLIGHTLY ABOVE SEASONAL AVERAGES.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... A DEAMPLIFIED...FLATTENED UPPER FLOW IS PROGGED BY MODEL ENSEMBLES THROUGH THE LONG TERM PERIOD. INDIVIDUAL SHORTWAVES ADVANCING THROUGH THE FLOW ACROSS THE UPPER OHIO VALLEY ARE EXPECTED TO BRING PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS. USED WPC ENSEMBLE BASED GUIDANCE TO SMOOTH OUT MODEL DIFFERENCES...WITH SOME ADJUSTMENTS TO POPS AND THE PROGGED SEASONALLY WARM TEMPERATURES. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... DIURNAL CU SHOULD DIMINISH SHORTLY WITH THE LOSS OF HEATING WITH ONLY SOME RESIDUAL CLOUDINESS ALONG THE RIDGES WHERE A BIT MORE MID-LOW LEVEL MOISTURE REMAINS. HIGH PRESSURE WILL SETTLE OVERHEAD TONIGHT WHICH SHOULD ALLOW FOR FOG FORMATION TOWARD SUNRISE AS DEWPOINT DEPRESSIONS GET SMALLER. QUESTION IS HOW SIGNIFICANT FOG FORMATION WILL BE. GENERALLY FEEL MOST CONFIDENT IN IFR VISIBILITIES WHERE LOW LEVEL MOISTURE...I.E DEWPOINTS...ARE HIGHEST THIS EVENING. HIGH CLOUDS OVER MGW MAY LIMIT RADIATIONAL COOLING AND FOG FORMATION BUT FOR NOW WILL CARRY IFR. FURTHER AWAY FROM THE RIDGES AND TOWARD LAKE ERIE CONFIDENCE IN WIDESPREAD IFR WAS LOWER...SO MVFR VISIBILITIES WERE CARRIED AT PIT/FKL FOR NOW. GUIDANCE DOES NOT SUGGEST MUCH FOG ANYWHERE...WHICH SEEMS TO BE INCORRECT WITH THE SATURATED GROUND AND DECOUPLING EXPECTED. CONDITIONS SHOULD RETURN TO VFR AFTER SUNRISE SUNDAY. .OUTLOOK.../SUNDAY NIGHT THROUGH WEDNESDAY/... RESTRICTION CHANCES ARE EXPECTED TO INCREASE EARLY NEXT WEEK WITH SEVERAL CROSSING DISTURBANCES. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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