Area Forecast Discussion
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000
FXUS61 KPBZ 012047
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
447 PM EDT WED OCT 1 2014

.SYNOPSIS...
THE NEXT CHANCE FOR RAIN WILL COME WITH A FRIDAY COLD FRONT.

&&

.NEAR TERM /THROUGH THURSDAY/...
UPDATE WAS ISSUED TO ADJUST FOR RAPIDLY DIMINISHED CLD COVER AS
MIXING AND SBSDNC HAVE FINALLY DEMOLISHED THE STRATUS LYR WHICH
PLAGUED THE UPR OH REGION TDA.

HOWEVER...LITTLE CHANGE IN THE BOUNDARY LAYER AIR MASS HAS
OCCURRED AND EXPECT FOG AND ST TO REDVLP AS THE NGT
PROGRESSES...ESPECIALLY WITH EWD DVLPG WARM FRONT/WARM ADVCTN
ALOFT ENHANCING THE INVERSION.

A QUICKER MIX OUT IS EXPECTED ON THURSDAY MRNG GIVEN THE IMPROVING
SLY FLOW IN THE BNDRY LYR AND INCRSD SBSDNC UNDR SHRTWV RIDGING.
THE INSOLATION AND MIXING SHOULD DRIVE TEMPS WELL INTO THE
70S...ABOUT 5 TO 10 DEGREES ABOVE THE AVGS REGION WIDE.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
H5 RIDGE AXIS IS PERCHED ATOP THE REGION FOR ONE LAST PERIOD BEFORE
WE ARE PUT BACK INTO REALITY WITH COOLER...MORE SEASONAL WEATHER.
DESPITE SOUTHEAST WINDS AT THE SURFACE...THEY DO NOT OCCUR LONG
ENOUGH NOR ARE THEY DEEP ENOUGH TO PROMOTE STATUS / DRIZZLE FOR
LOCATIONS THAT ARE SUSCEPTIBLE /JEFFERSON CO PA S INTO EASTERN
GARRETT/.

OVERALL TREND OF SLOWING PRECIP ONSET CONTINUES TO BE THE COURSE OF
ACTION.  LATEST 12Z NCEP SUITE PORTRAYS THE THEME OF QPF REACHING
WESTERN FRINGES OF CWA BY 15Z FRIDAY.  CAT POPS ARE STILL GOOD FOR
THIS SYSTEM AS ALL LOCATIONS SHOULD SEE ONE TO TWO TENTHS OF RAIN.
WET WEATHER WILL BE PREDOMINATE IN THE AFTERNOON AND EVENING HOURS
JUST AHEAD OF THE BAROCLINIC ZONE.  DECENT WIND FIELD ASSOCIATED
WITH THIS SYSTEM WITH H8 WINDS OF 60KTS AND H5 NEAR 100KTS...SO
GUSTY SHOWERS AND PERHAPS A THUNDERSTORM IS NOT OUT OF THE
QUESTION.  THE STRENGTH OF THE WIND FIELD AND MIXING HEIGHTS FRIDAY
NIGHT MAY YIELDS GUSTS BETWEEN 30-35 KNOTS.  THERMODYNAMIC
PARAMETERS ARE MARGINAL WITH DYNAMIC FORCING THE LARGE CONTRIBUTOR
TO ANY THUNDERSTORM INITIATION.  A CHANCE OF THUNDER REMAINS
FORECAST.

MUCH COOLER WEATHER IS IN STORE THIS WEEKEND AS H8 TEMPS PLUMMET
FROM 14C TO 0C.  DAYTIME HIGHS SATURDAY WILL FEEL MORE LIKE LATE OCT
AS THEY TOP OUT ONLY IN THE 50S.  THERE WILL BE A PERIOD OF SUNSHINE
AS THE DRY CONVEYOR BELT PASSES...BUT CLOUDS WILL QUICKLY FILL IN
DUE TO DESTRUCTIVE SUNSHINE.  SUBSTANTIAL COOLING ALOFT WITH VERY
UNSTABLE LOW AND MID LEVELS DENOTED BY LAPSE RATES PUSHING 9CKM-1
SATURDAY WILL GENERATE SCATTERED SHOWERS.  CYCLONE TRACK KEEPS WINDS
WSW SAT NIGHT...WHICH SHOULD KEEP TEMPS IN THE 40S FOR OVERNIGHT
LOWS.  EVEN IF TEMPS WERE TO BOTTOM OUT IN THE MID 30S...AMOUNT OF
CLOUD COVER AND PRESSURE GRADIENT AT THE SURFACE WOULD OFFSET FROST
DEVELOPMENT.

WINDS WILL STAY MIXED ALLOWING FOR A MILD NIGHT THUR SO SIDED WITH
THE WARMER NAM12 GRIDS...THEN TOOK A BLEND OF THE FORECAST AND BIAS
CORRECTED MOSGUIDE GRIDS FOR MAX/MIN TEMPS.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
COLD AIR ALOFT WILL HELP TO KEEP SHOWERS NORTH OF I-80 SUNDAY WITH
DRY AND COOL CONDITIONS ELSEWHERE. STRONG CLOSED LOW ALOFT WILL
WOBBLE NORTH OF LAKE HURON MONDAY AND TUESDAY WITH SHORTWAVES
RIDING UNDER THE LOW BRINGING PERIODS OF SHOWERS. BY MIDWEEK UPPER
TROUGH WILL LIFT NORTH WITH ZONAL FLOW DEVELOPING ACROSS THE OHIO
VALLEY.

TEMPERATURES WILL BE BELOW SEASONAL AVERAGES TO START THE
WEEK...MODERATING BY MID WEEK.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
GENL VFR IS EXPECTED THROUGH THE EVE AS STRATUS LYR FINALLY HAS
ERODED. HOWEVER...CONDITION DETERIORATION IS EXPECTED THROUGH THE
NGT WITH FOG AND ST DVLPMNT ONCE AGAIN UNDR A STRENGTHENING
INVERSION. IFR IS THUS FORECAST FOR ALL SITES...BUT IMPROVEMENT
AFTR DAYBREAK IS EXPECTED TO BE MORE RAPID THAN TDA GIVEN BTR
MIXING AND SBSDNC CONDITIONS.


OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
THE NXT CHC FOR WIDESPREAD RESTRICTIONS WL COME WITH A FRIDAY CDFNT.

&&

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

&&

$$

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