Area Forecast Discussion
Issued by NWS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KPBZ 191348
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
948 AM EDT SUN APR 19 2015

.SYNOPSIS...
A DRY BEGINNING TO THE DAY...BUT SHOWERS WILL OVERSPREAD THE
REGION THIS AFTERNOON AND CONTINUE THROUGH MONDAY. UNSEASONABLY
COOL TEMPERATURES ARE EXPECTED FOR THE REMAINDER OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
A FEW THUNDERSTORMS DEVELOPED JUST AFTER SUNRISE IN EASTERN OHIO
AND HAVE SINCE MOVED OFF INTO NORTHERN OHIO. NOT MUCH FURTHER
DEVELOPMENT OF THESE SHOWERS/THUNDERSTORMS IS EXPECTED SO FAR
AHEAD OF THE WARM FRONT POISED TO BRING RAIN SHOWERS TO THE AREA
LATER TODAY.

A LOOK AT THE 12Z UPPER AIR SOUNDING REVEALS TWO SUBSTANTIAL
LAYERS OF DRY AIR...ONE NEAR THE SURFACE AND ANOTHER FROM
700MB-500MB. THIS HAS RESULTED IN A MOSTLY SUNNY MORNING FOR MUCH
OF THE AREA...ALLOWING FOR TEMPERATURES TO RISE RAPIDLY AFTER
MIXING BEGAN. STRONGER WINDS JUST OFF THE SURFACE HAVE MIXED DOWN
RESULTING IN SOME EARLY GUSTS CLOSE TO 20KTS. THESE GUSTS ARE
EXPECTED TO CONTINUE THROUGH THE DAY AS THE PRESSURE GRADIENT
TIGHTENS WITH THE SYSTEM DRAWING NEAR.

DAYTIME HIGHS WILL BE DEPENDENT UPON ARRIVAL OF CLOUDS AND
PRECIPITATION AND THE WARMING/COOLING TREND WILL SHIFT FROM SOUTH
TO NORTH AS A RESULT. TRIED TO CONVEY THIS HOURLY TEMPERATURE
TRANSITION IN THE FORECAST AS MUCH AS POSSIBLE.

TIMING OF THE PRECIPITATION LOOKS TO BE ON TRACK WITH EARLIER
FORECASTS...WITH THE RAIN REACHING OUR SOUTHERN ZONES BY
MIDDAY...PITTSBURGH BY LATE AFTERNOON. KEPT THE CATEGORICAL POPS
IN FOR THIS EVENING/EARLY TONIGHT...DESPITE THE LATEST HI-RES
GUIDANCE SHOWING CONSIDERABLE MOISTURE EROSION UPON ARRIVAL. THIS
MAKES SOME SENSE GIVEN THE AMOUNT OF DRY AIR SAMPLED BY THE
MORNING SOUNDING. WILL WAIT FOR THE REST OF THE 12Z GUIDANCE
BEFORE MAKING ANY MAJOR UPDATES TO THE FORECAST.
TAX

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
SHOWER COVERAGE WILL DECREASE OVERNIGHT AS UPPER LEVEL SUPPORT
SHIFTS TO THE EAST AND A LARGE UPPER LEVEL DRY SLOT OVERSPREADS
THE AREA.

THE RESULTING SUBSIDENCE IS EXPECTED TO CONTINUE THROUGH MONDAY
MORNING...AND MAY PROMOTE MODEST HEATING OF A RELATIVELY-MOIST
BOUNDARY LAYER WITH 45-50KT OF SOUTHWEST FLOW ALOFT.

A SECOND SHORTWAVE TROUGH IS PROJECTED TO MOVE QUICKLY NORTHEASTWARD
AND CROSS THE REGION BY LATE DAY. LIFT IN ASSOCIATION WITH THAT
DISTURBANCE WOULD AID CONVECTIVE DEVELOPMENT DURING THE
AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED WITH
THIS SCENARIO. WIDESPREAD SEVERE THUNDERSTORMS ARE NOT EXPECTED
OWING TO PROGNOSIS OF WEAK MID LEVEL LAPSE RATES.

UNUSUALLY STRONG UPPER LOW PRESSURE IS FORECAST TO BUILD SEWD
INTO THE GREAT LAKES REGION BY TUESDAY...WITH ITS ASSOCIATED COLD
FRONT TO CROSS THE FORECAST AREA DURING THE MORNING.

COLD ADVECTION BEHIND THE FRONTAL PASSAGE IS PROGGED TO PROVIDE
INCREASED COVERAGE OF STRATOCU AND POSSIBLE LAKE ENHANCEMENT TO
LIGHT PRECIPITATION...WITH THAT LIMITED TO THE NORTHERN ZONES WITH
EXPECTATIONS OF WESTERLY FETCH AND DRY ADVECTION.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
BROAD UPPER TROUGHING WILL REMAIN OVER THE EASTERN CONUS THROUGH
THE EXTENDED AND RESULT IN BELOW NORMAL TEMPERATURES EACH DAY
ALONG WITH CLOUDY SKIES AND SLIGHT CHANCES FOR PRECIPITATION
THROUGHOUT THE PERIOD AS SHORTWAVES TRANSITION THROUGH THE FLOW
AND CAA ALOFT PERSISTS. CONFIDENCE IS HIGH IN THE GENERAL FORECAST
AS MODELS HAVE BEEN FAIRLY CONSISTENT IN PROGGING THIS LONGWAVE
PATTERN...REFLECTED IN LATEST RMOP AND MODTRENDS GUIDANCE.
HOWEVER...CONFIDENCE IN TIMING OF ANY MORE SIGNIFICANT PERIODS OF
PRECIPITATION IS RELATIVELY LOW. FORECAST MAX/MIN TEMPERATURES ARE
NOT EXCEPTIONALLY COLD...BUT PERSISTENT AROUND 10 DEGREES BELOW
NORMALS AS ENSEMBLE ANOMALIES ARE SHOWING TEMPS AND HEIGHTS ALOFT
ONLY RANGING FROM 1-2 STANDARD DEVIATIONS BELOW NORMAL THROUGH THE
PERIOD.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
NO RESTRICTIONS ARE ANTICIPATED UNTIL RAIN SHOWERS ASSOCIATED
WITH THE WARM FRONT DEVELOP LATE THIS AFTERNOON. EXPECTING RAIN TO
FALL OUT OF MOSTLY VFR CIGS...BUT HEADING INTO THE OVERNIGHT THE
CIGS SHOULD CONTINUE THIER DESCENT TO MVFR. GUSTY EAST-
SOUTHEASTERLY FLOW WILL CONTINUE THROUGH THE DAY AND
OVERNIGHT...GRADUALLY RELAXING THROUGH THE EARLY MORNING MONDAY.
TAX

.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
PERIODIC RESTRICTIONS ARE EXPECTED THROUGH MONDAY NIGHT AS LOW
PRESSURE CROSSES THE REGION. RESTRICTIONS ARE POSSIBLE WITH A MID
WEEK UPPER TROUGH.

&&

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

&&

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.