Area Forecast Discussion
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FXUS61 KPBZ 222342
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
742 PM EDT TUE JUL 22 2014

.SYNOPSIS...
THE AREA WILL SEE SHOWERS AND THUNDERSTORMS ON WEDNESDAY AS COLD
FRONT PASSES ACROSS THE REGION...WITH SLIGHTLY BELOW NORMAL
TEMPERATURES AND DRY CONDITIONS THE REMAINDER OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
6 PM - UPDATED TO AMP UP POPS SLIGHTLY FOR THE SOUTHEAST RIDGES
WHERE SHRA CONTINUE TO FIRE...THIS SHOULD CONTINUE FOR A FEW HOURS
UNTIL JUST AFTER SUNSET...WHEN THESE AND ANY REMAINING CU WILL
FALL APART.  MINOR CHANGES OTHERWISE.

PREVIOUS DISCUSSION...

CUMULUS BUILDUPS CONTINUE TO BE LIMITED BY A FAIRLY STRONG CAP
AROUND 10 KFT. HOWEVER...STRONG LOW LEVEL LAPSE RATES GENERATED
BY INTENSE INSOLATION EARLIER TODAY AND A FAIRLY MOIST COLUMN
BELOW 10 KFT HAVE MANAGED TO ALLOW FOR SAID CUMULUS TO BE QUITE
WIDESPREAD AROUND THE REGION. THAT SAID...ONLY AROUND THE HIGHEST
RIDGELINES DO THESE BUILDUPS SEEM TO BE CAPABLE OF REACHING
SUFFICIENT VERTICAL EXTENT TO CAUSE A SHOWER OR TWO.

OVERNIGHT...DIURNAL CUMULUS WILL QUICKLY FADE AS RAGGED MID-CLOUD
APPROACHES FROM THE NORTHWEST. THIS WILL BE AN EARLY HARBINGER OF
THE WEATHER FOR WEDNESDAY...HOWEVER THE BEST COLUMN RH VALUES FAIL
TO REACH OUR CWA PRIOR TO SUNUP. AS A RESULT...GENERALLY CLEAR
SKIES SEEM LIKELY TO DOMINATE THE REGION OVERNIGHT. HOWEVER...WITH
STRONG WARM ADVECTION AT THE TOP OF THE BOUNDARY LAYER...RIDGETOP
TEMPERATURES ARE LIKELY TO STAY WELL UP OVERNIGHT AS 17-18C IS
ABOUT AS LOW AS WE WILL MUSTER AT 850 MB. RADIATIONAL COOLING WILL
LIKELY BE A BIT MORE EFFECTIVE IN THE VALLEYS...HOWEVER DEWPOINTS
STRADDLING 70F WILL MAKE DIURNAL FALLS DIFFICULT TO MANAGE. AS A
RESULT...A WARM NIGHT IS EXPECTED ACROSS THE REGION...WITH SOME
PATCHY RIVER FOG POSSIBLE BY MORNING AND AHEAD OF THE INCOMING
CLOUDS FROM THE NEXT SYSTEM. FRIES

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
A COLD FRONT WILL PASS ACROSS THE FORECAST AREA WEDNESDAY
AFTERNOON THROUGH WEDNESDAY NIGHT. SCATTERED THUNDERSTORMS WILL
DEVELOP DURING THE AFTERNOON AHEAD OF THE FRONT WITH SFC
DEWPOINTS STILL IN UPPER 60S TO LOW 70S AND MID LEVELS BEGINNING
TO COOL AS HEIGHTS FALL. INSTABILITY IS NOT ENTIRELY IMPRESSIVE
WITH LOCAL HI RES MODELS PROGGING THE HIGHEST LEVELS OF
CAPE...AROUND 1500-1700J/KG. CONVECTION SHOULD REMAIN FAIRLY
UNORGANIZED AS SHEAR STILL LOOKS TO BE MARGINAL AT BEST. SCATTERED
SHOWERS WILL LINGER BEHIND THE FRONT OVERNIGHT AS THE ASSOCIATED
MIDLEVEL SHORTWAVE PASSES. DRY CONDITIONS AND COOLER TEMPERATURES
WILL THEN PREVAIL THE REMAINDER OF THE WEEK AS HIGH PRESSURE
BUILDS IN ACROSS THE REGION.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
DRY HIGH PRESSURE WILL DOMINATE INTO SATURDAY. BY SATURDAY NIGHT
INTO SUNDAY NEXT SYSTEM WILL APPROACH FROM THE GREAT LAKES WITH
INCREASING DEW POINTS AND CHANCE POPS FOR SHOWERS AND
THUNDERSTORMS. A SERIES OF COLD FRONTS WILL THEN BRING COOLER
TEMPERATURES WITH CONTINUED SHOWER CHANCES INTO EARLY NEXT WEEK.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
CLEARING TREND CONTINUES INTO THE OVERNIGHT HOURS WITH A COLD
FRONT STILL WELL TO THE WEST. TEMPERATURES AND DEWPOINTS ARE A FEW
DEGREES HIGHER THAN 24 HOURS AGO...BUT THE SPREAD BETWEEN REMAINS
ABOUT THE SAME. NOT EXPECTING CLOUDS ASSOCIATED WITH THE COLD
FRONT TO MAKE IT INTO THE AREA UNTIL AROUND SUNRISE WEDS...SO A REPEAT
OF MON NIGHT/TUES MORNING COULD BE IN STORE. IN SHORT...SHOULD
SEE DEVELOPMENT OF MVFR FOG FOR MOST TERMINALS...THE MORE FOG PRONE
TERMINALS COULD DROP TO IFR OR WORSE.

ANY OVERNIGHT FOG SHOULD QUICKLY DISSIPATE AFTER DAYBREAK WEDS AS
INCREASED SW SFC FLOW KICKS IN AHEAD OF THE COLD FRONT. RAIN
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH THE FRONT COULD CAUSE
SOME TEMPORARY RESTRICTIONS BEGINNING AROUND MIDDAY WEST THROUGH
THE LATE EVENING EAST. A WIND SHIFT WILL ALSO OCCUR WITH THE
FRONT...WITH 5-10KT WINDS FROM THE NORTHWEST WEDS EVENING.
TAX

OUTLOOK.../TUESDAY NIGHT THROUGH SATURDAY/...
GENERAL VFR THURSDAY INTO SATURDAY AS HIGH PRESSURE RETURNS TO THE AREA.

&&

.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.

&&

$$






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