000
FXUS61 KPBZ 170120
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
920 PM EDT THU MAY 16 2013

.SYNOPSIS...
A COLD FRONT WILL BE NEARLY STATIONARY THROUGH FRIDAY THEN WAVER
OVER PORTIONS OF THE UPPER OHIO VALLEY INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH FRIDAY/...
WITH LOSS OF DIURNAL HEATING...PLUS UPPER LEVEL WAVE MOVING OFF
TO THE EAST...ALL PRECIPITATION HAS COME TO AN END FOR THE
EVENING. FRONT REMAINS DRAPED ACROSS THE REGION...WITH DEWPOINT OF
43 AT INDIANA AND 46 AT ALLEGHENY COUNTY AIRPORT...WHILE
MORGANTOWN DEWPOINT IS 60 DEGREES. ALTHOUGH SOME CLOUDS WILL
REMAIN ALONG THE MASON-DIXON LINE...EXPECT ALL OTHER LOCATIONS TO
REMAIN MOSTLY CLEAR OVERNIGHT. LOW FORECAST FOR TONIGHT STARTED
WITH A NEAR EVEN BLEND OF GFS/NAM MOS...WITH FURTHER REFINEMENTS
FROM GFSLAMP/RAP GUIDANCE.

THE FRONT WILL STALL ACROSS WEST VIRGINIA FRIDAY WITH DRY AIR
ENCOMPASSING MUCH OF THE REGION. SCATTERED SHOWERS STILL POSSIBLE
ACROSS THE FAR SOUTH. PARTLY TO MOSTLY SUNNY SKIES ACROSS ALL BUT
THE FAR SOUTH CLOSER TO THE FRONT. NAM MOS SEEMS TOO COOL FOR MAX
TEMPS BUT DID GO A DEGREE OR TWO BELOW GFS MOS IN WEAK COLD
ADVECTION.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
FOR FRIDAY NIGHT INTO SUNDAY GENERAL AGREEMENT THAT BOUNDARY WILL
PUSH NORTHWARD BUT AGAIN DISAGREE ON TIMING AND STRENGTH OF
POSSIBLE SHORTWAVES. IF GFS IS MORE CORRECT SOUTHERN STREAM ENERGY
WOULD WORK TOWARD THE REGION LATER SATURDAY INTO EARLY SUNDAY WITH
HIGHER RAIN CHANCES. NOT MUCH CONFIDENCE IN THIS. SO TRENDED
TOWARD NAM SOLUTION WITH HIGHEST SHOWER CHANCES ACROSS THE SOUTH
AND RIDGES THROUGH THE WEEKEND. TEMPERATURES NOT FAR FROM GFS MOS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
MODEL AGREEMENT ON THE OVERALL UPPER LEVEL PATTERN IS BEGINNING TO
IMPROVE...AT LEAST THROUGH DAY 6 BEFORE THERE ARE GLARING
DIFFERENCES. IN GENERAL...UPPER LEVEL RIDGING WILL CONTINUE TO
AMPLIFY OVER THE EASTERN HALF OF THE CONUS AS A CUTOFF LOW DEVELOPS
OVER THE NORTHERN PLAINS. THIS LOW WILL SLOWLY MAKE IT`S APPROACH
THROUGH THE PERIOD...HELPING TO SWING AN ASSOCIATED FRONT ACROSS THE
REGION BY LATE WEDNESDAY/EARLY THURSDAY. HOWEVER...DIFFERENCES STILL
REMAIN IN THE AMOUNT OF CONVECTIVE ACTIVITY THERE WILL BE IN THE
WARM SECTOR SUNDAY THROUGH WEDNESDAY AS DIFFERENT SHORTWAVES MOVING
THROUGH THE UPPER LEVEL FLOW ARE TIMED DIFFERENTLY FROM RUN TO RUN.
TO TAKE INTO ACCOUNT THESE DIFFERENCES...OPTED TO REMAIN
CONSERVATIVE WITH POPS UNTIL LATE TUESDAY BEFORE INCREASING CHANCES
IMMEDIATELY AHEAD OF THE COLD FRONT. TEMPERATURES WERE ALSO KEPT
BELOW MOS GUIDANCE...ESPECIALLY ON TUESDAY AND WEDNESDAY AS AMPLE
MOISTURE AND CLOUD COVER WILL LIKELY KEEP TEMPERATURES FROM REACHING
THE MID 80`S SUGGESTED.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
STATIONARY/MEANDERING FRONT WAS ANALYZED NR A ZZV TO MGW LINE THIS
EVE AND WL CONT TO BE THE FOCUS FOR LLVL MSTR. WHILE MOST OF THE
TAF SITES SHOULD REMAIN VFR OVERNIGHT WITH LGT...VARIABLE SFC
WND...MGW AND ZZV COULD EXPERIENCE SOME FOG/CIG RESTRICTIONS IN
THE PREDAWN HRS GIVEN THEIR PROXIMITY TO THE FRONT.

WITH MDL-DISPARITY ON EVENTUAL PLACEMENT OF THE FRONTAL BNDRY AS
THE NGT PROGRESSES...HAVE PERSISTED WITH A MVFR FOG MENTION AT ZZV
AND MGW FOR THE PREDAWN HOURS.

OTHERWISE...VFR CONDITIONS CAN BE ANTIICIPATED THROUGH FRIDAY.

.OUTLOOK.../FRIDAY NIGHT THROUGH TUESDAY/...
GENERAL VFR SHOULD CONTINUE UNTIL SATURDAY AFTERNOON WHEN INCRSG
MSTR AND INSTABILITY SPPRT PCPN CHCS AND RESTRICTIONS...WHICH ARE
EXPECTED TO PERIODICALLY CONT THROUGH TUESDAY.

&&

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

&&

$$