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NWS Area Weather Forecast Discussion
County Warning Area [CWA]: PBZ
Regional NWS Weather Office: Pittsburgh, PA

000
FXUS61 KPBZ 291721
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
121 PM EDT FRI APR 29 2016

.SYNOPSIS...
LOW PRESSURE WILL MAINTAIN CLOUDY SKIES WITH SHOWER CHANCES
TODAY. THE NEXT SYSTEM WILL BRING WIDESPREAD RAIN LATER SATURDAY
AND INTO SUNDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
STAGNANT COOL AND MOIST AIR MASS WILL CONTINUE TO PLAGUE THE AREA
THROUGH TONIGHT. SOME EROSION OF LOW STRATUS IS DEVELOPING ON THE
SOUTHERN FLANK...ALLOWING FOR SCATTERING AND WARMING SOUTH OF THE
MASON-DIXON LINE. THIS WILL AGAIN SET UP A SHARP GRADIENT IN
TEMPERATURES THIS AFTERNOON WITH NORTHERN WEST VIRGINIA GETTING
INTO THE UPPER 60S...WHILE NORTH OF I-80 MAY TOUCH 50 DEGREES.

SHORTWAVE TROUGH AXIS CURRENTLY CROSSING LAKE ERIE WILL SKIRT THE
NORTHERN HALF OF THE FORECAST AREA THIS AFTERNOON. EXPECT CURRENT
SHOWER ACTIVITY TO BLOSSOM NORTH OF PITTSBURGH IN RESPONSE TO THE
QUICK PASSING WAVE. ADDITIONALLY...HI-RES CAMS SHOW SHOWERS
DEVELOPING JUST SOUTH OF PITTSBURGH. GIVEN THE STEEPENING LOW-
LEVEL LAPSE RATES...LIFT FROM THE WAVE AND COPIOUS
MOISTURE...THINK THAT CHANCE POPS THROUGH AND SOUTH OF THE
PITTSBURGH METRO AREA SEEM PRUDENT.

WAVE PASSES TO THE EAST TONIGHT AND SOME DRYING WILL OCCUR.
MOISTURE WILL BEGIN TO ERODE FROM THE WEST...SCATTERING OUT THE
LOW CLOUDS...BUT TIMING IS DIFFICULT TO PIN DOWN AT THIS POINT.
LOW TEMPERATURES WILL DEPEND LARGELY ON TIMING AND EXTENT OF
CLEARING OVERNIGHT. WITH THIS IN MIND...HAVE WESTERN PORTIONS OF
THE FORECAST AREA RELATIVELY LOW COMPARED TO EASTERN PORTIONS.
TAX

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
A FEW SHOWERS MAY LINGER IN THE EAST THIS EVENING AS UPPER LEVEL
ENERGY QUICKLY MOVES TOWARD SOUTHEASTERN PA. HUNG ON TO CLOUDS
THROUGH THE NIGHT...PARTICULARLY OVER THE EASTERN HALF OF THE
AREA...AS MODELS ARE SHOWING LOW AND MID-LEVEL MOISTURE BECOMING
TRAPPED UNDER THE RISING HEIGHTS ALOFT.

UPPER LEVEL HEIGHTS WILL CONTINUE TO RISE SATURDAY IN RESPONSE TO
DEEPENING SYSTEM OVER THE CENTRAL PLAINS. THIS WILL ALLOW FOR A
BREAK IN THE ACTIVITY FOR A PORTION OF SATURDAY. SHOWERS WILL
BEGIN TO OVERSPREAD THE WESTERN HALF OF THE AREA SATURDAY
AFTERNOON AND THEN THE REST OF THE AREA BY EVENING. STILL SEEING
SOME TIMING DIFFERENCES WITH THE SHOWERS...BUT IT DOES SEEM THAT
MODELS ARE SPEEDING UP THEIR ONSET.

TEMPERATURE INCREASES SATURDAY...AS WARMER AIR MOVES IN AHEAD OF
THE AFOREMENTIONED SYSTEM.

SHOWERS WILL CONTINUE INTO SUNDAY...BUT AGAIN...DIFFERENCES IN
OPERATIONAL MODEL DATA WITH THE SPEED AND LOCATION OF THE SURFACE
LOW...MAKE FOR A LOW CONFIDENCE FORECAST. WILL RELY ON THE
SUPERBLEND HERE TO ATTEMPT TO OVERCOME MODEL DISCREPANCIES.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
SHOWER COVERAGE WILL DECREASE SUNDAY NIGHT/EARLY MONDAY AS THE
ENTIRE SYSTEM MOVES OFF THE EAST COAST. A DRY PERIOD APPEARS
LIKELY TUESDAY AND POSSIBLY INTO WEDNESDAY. THERE CONTINUES TO BE
UNCERTAINTY WITH THE TIMING/DEPTH OF A DEVELOPING EASTERN TROUGH
FROM WEDNESDAY ON...AS A WESTERN RIDGE ELICITS A RESPONSE
DOWNSTREAM. CHANCE POPS APPEAR WISE FOR A PORTION OF WEDNESDAY AND
INTO THURSDAY AS THE POTENTIAL FOR SHOWERS INCREASES. USED
SUPERBLEND FOR THE LONG TERM AS WELL.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
IFR RESTRICTIONS GRADUALLY IMPROVING TO LOW MVFR...PRIMARILY SOUTH
OF PITTSBURGH WHERE SOME SCATTERING IS NOTED ON SATELLITE. ANOTHER
SHORTWAVE TROUGH WILL PASS ACROSS THE NORTH THIS
EVENING...REINFORCING THE LOW CIGS ACROSS THE NORTH. THIS WAVE
WILL ALSO GENERATE ADDITIONAL LIGHT RAIN SHOWERS...MAINLY FOR
NORTHERN AND EASTERN PORTS.

HIGH CONFIDENCE IN IFR CONDITIONS REOCCURRING TONIGHT...BUT AFTER
THE PASSAGE OF THE WAVE...LOWER-LEVELS BEGIN TO DRY OUT FROM THE
WEST. THIS WILL RESULT IN SOME AMOUNT OF SCATTERING/CLEARING FROM
KZZV EASTWARD NEAR DAYBREAK SATURDAY. CONFIDENCE IS MUCH LOWER ON
THE AMOUNT AND EXACT TIMING OF THE IMPROVEMENT NEAR SUNRISE. VFR
CONDITIONS ARE THEN EXPECTED FROM SATURDAY MID-MORNING THROUGH
THE DURATION OF THE OPERATIONAL TAF PERIOD.

LIGHT WEST WINDS WILL VEER TO THE NORTHWEST TONIGHT IN THE WAKE OF
THE PASSING WAVE. LIGHT NORTH WINDS TONIGHT WILL THEN VEER TO
EASTERLY SATURDAY. WIND SHOULD GENERALLY STAY 10KTS OR LESS
THROUGH THE PERIOD.
TAX

.OUTLOOK /FRIDAY NIGHT THROUGH TUESDAY/...
RESTRICTIONS ARE LIKELY AGAIN LATE SATURDAY THROUGH SUNDAY NIGHT
AS LOW PRESSURE CROSSES THE REGION.

&&

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

&&

$$

Forecast Discussion from: NOAA-NWS Script developed by: El Dorado Weather