Area Forecast Discussion
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000
FXUS61 KPBZ 041800
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
200 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/...
MORNING LOW CLOUDS HAVE BROKEN INTO A SCT-BKN CU DECK. DRIER AIR
WORKING IN FROM THE NW HAS KEPT CU COVERAGE MUCH LESS ACROSS OH AND
FAR NW PA. MOST OF THESE WILL COLLAPSE WITH SUNSET. STILL CANNOT
RULE OUT A SPRINKLE OR LIGHT RAIN SHOWER ALONG THE EASTERN
RIDGES THIS AFTERNOON...BUT THESE WILL BE QUITE MINOR AND BRIEF.
SURFACE HIGH PRESSURE AND WEAK H500 RIDGING WILL THEN LEAD TO DRY
WEATHER TONIGHT. THE RECENT RAINFALL AND CALM WINDS OVERNIGHT MAY
LEAD TO AT LEAST PATCHY LIGHT FOG IN MANY AREAS TONIGHT. THE
EASTERN VALLEYS FIGURE TO HAVE THE BEST CHANCE GIVEN DRIER
DEWPOINTS ARRIVING HERE LAST...AND HAVE ADDED SOME PATCHY FOG TO
THE GRIDS HERE.

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.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
DRY...AND WARMER WEATHER IS THEN EXPECTED AS HIGH PRESSURE BUILDS
THROUGH SUNDAY. HOWEVER...MODELS NOW DIFFER SIGNIFICANTLY IN
DEPICTIONS OF MONDAY WEATHER AS ANOTHER DISTURBANCE IN FLOW...ALBEIT
WEAK AND BROAD...IS NOW PROJECTED TO INVADE FROM THE SOUTH AND
ERODE THE RIDGE.

GIVEN THE INCONSISTENCY...WILL NOT HIT THIS TOO HARD AT
MOMENT...BUT THE ENSEMBLE AND DETERMINISTIC TREND CAN NOT BE
IGNORED SO FORECAST WILL INCLUDE SOME DIURNALLY SUPPORTED CHANCE
POPS FOR MONDAY...AS WELL AS INCREASING CHANCE NUMBERS WITH THE
TUESDAY FRONTAL SYSTEM.

THE SHORT TERM TEMP FORECAST WITH THESE CHANGES STILL LOOKS WARM...BUT
READINGS WERE TEMPERED CLOSER TO THE SEASONAL AVERAGES.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
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 /18Z SATURDAY THROUGH THURSDAY/...
VFR CONDITIONS THROUGH THE EVENING WITH SCT-BKN CU AND NW WINDS AT
10 KNOTS OR LESS. WITH HIGH PRESSURE MOVING OVERHEAD TONIGHT...AND
THE RESULTING CLEAR SKIES AND LIGHT WINDS...EXPECT MVFR TO IFR FOG
TO FORM AFTER MIDNIGHT. LOCATIONS LIKE LBE AND DUJ MAY EVEN SEE
LIFR...DUE TO WETTER GROUND AND LOWER DEWPOINT AIR ARRIVING LATER
THAN AREAS TO THE WEST. FOG WILL BURN OFF BY 13-14Z...LEAVING
MAINLY HIGH CLOUDS AND FEW CU IN ITS WAKE.

.OUTLOOK.../SUNDAY 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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