Area Forecast Discussion
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000
FXUS61 KPBZ 211540
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1140 AM EDT TUE OCT 21 2014

.SYNOPSIS...
DAMP AND COOL WEATHER WILL CONTINUE UNTIL UPPER LOW PRESSURE
SHIFTS EASTWARD DURING THE LATTER HALF OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
IMPRESSIVE CIRCULATION PRESENT ON CURRENT RADAR AS AN MCV FEATURE
IS VERY SLOWLY MOVING W TO E ACROSS THE NRN 1/3 OF THE CWA.
DESPITE ENHANCED RADAR REFLECTIVITIES ALONG THE NRN EDGE OF THE
MCV CIRCULATION...THE HIGHEST RAINFALL REPORTS RECEIVED HAVE BEEN
AROUND 1/3" PER HR. EXAMINATION OF THE INDIVIDUAL RADAR SLICES
REVEALS THAT A GOOD PORTION OF THE ENHANCEMENT IS DUE TO BRIGHT
BANDING ON THE RADAR...WITH FREEZING LEVELS RIGHT AROUND 7KFT.

LATEST WATER VAPOR IMAGERY SHOWS ANOTHER SW SWINGING SOUTH THROUGH
LAKE ERIE WITH AN ATTENDANT VORT MAX THROUGH OHIO. THIS IS
GENERATING LAKE ENHANCED RAIN SHOWERS OVER THE SRN SHORE OF LAKE
ERIE EXTENDING INTO OUR NRN CWA AND CONGEALING WITH THE BACK EDGE
OF THE SLOW MOVING CIRCULATION CURRENTLY OVER THE NE CWA. THIS
VORT WILL EFFECTIVELY CUT-OFF THE UPPER LOW OVER THE NEXT SEVERAL
HOURS AND ALLOW IT TO DRIFT RIGHT OVERTOP OF US. WITH COPIOUS
AMOUNTS OF LLVL MOISTURE AND THE COLD POOL ALOFT MAXIMIZING OVER
OUR AREA NEXT SEVERAL HOURS...WOULD EXPECT FURTHER DEVELOPMENT OF
CONVECTIVELY DRIVEN RAIN SHOWERS. WE ARE ALREADY BEGINNING TO SEE
THIS OVER NRN WV AFTER A RELATIVELY DRY MORNING.

TONIGHT THE UPPER LOW DRIFTS SOUTH OF THE AREA...ENHANCING NRLY
FLOW ALOFT WRAPPING MOISTURE BACK AROUND THE SYSTEM. THE LLVL FLOW
WILL REMAIN NWRLY ENABLING AN UPSLOPE COMPONENT...THUS WILL
CONTINUE THE LIKELY POPS IN THE SE RIDGES. ELSEWHERE...MULTIPLE
WEAK MID-LEVEL VORTS ARE PROGGED TO SWING AROUND THE PARENT
LOW...AND SHOULD CONTINUE TO AID THE DEVELOPMENT OF LIGHT RAIN
SHOWERS. KEEPING CHC POPS IN ACROSS MUCH OF THE CWA THROUGH WEDS
MORNING. WITH TEMPS MODERATED BY CLOUD COVER AND SHOWER
ACTIVITY...LARGE MODIFICATIONS WERE NOT NECESSARY.
TAX

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
COLD MID LVLS WL PERSIST OVR THE REGION THROUGH WEDNESDAY DESPITE
THE LOW CNTR SHIFTING TWD THE COAST. DESPITE A CONSIDERABLE
REDUCTION IN POPS...SHWRS CHCS IN THE LOW THRESHOLD CONVECTIVE
ENVIRONMENT WERE MAINTAINED WITH EMPHASIS OVR THE UPSLOPE AREAS
ALNG THE I 80 CORRIDOR AS WELL AS THE RIDGES. THEREAFTER...WARMING
ALOFT/LOWERING INVERSION IS FORECAST TO SUPPRESS PCPN CHCS ON
THURSDAY...ALTHOUGH SLGT TO CHC NMBRS WERE KEPT OVR THE HIGHER
ELEVATIONS IN COLLABORATION WITH NEIGHBORING WFOS.

TRAILING SHRTWV IS PROGGED FOR A FRIDAY CROSSING OF THE REGION...BUT
SOME CLDS ARE ALL THAT IS ANTICIPATED GIVEN THE LACK A THERMAL TROF
ALOFT AS WELL AS SUFFICIENTLY DEEP MSTR.

SHORT TERM TEMPS WERE TWEAKED USING BIAS CORRECTED GFS MOS TRENDS...BUT
LITTLE CHANGE WAS NEEDED.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
BLDG RIDGING ACRS THE CNTRL CONUS WL SHIFT E THRU ERLY NXT WK
KEEPING DRY WEA IN THE FCST. SEASONALLY COOL TEMPS ARE EXP TO PUSH
ABV AVG LVLS BY ERLY NXT WK.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
A LARGE AND VERY SLOW MOVING SYSTEM IS MOVING THROUGH THE GREAT
LAKES AND ACROSS THE AREA OVER THROUGH WEDS. THE MOISTURE ASSOCIATED
WITH THIS SYSTEM IS FOUND PRIMARILY IN THE LOW TO MID-LEVELS WITH
AN EXPANSIVE CLOUD DECK AND LIGHT RAIN SHOWERS GENERATED...THUS MVFR-IFR
CONDITIONS ARE EXPECTED AREA-WIDE THROUGH MID-MORNING WEDS. AS OF
15Z MOST TERMINALS HAVE IMPROVED TO MVFR...BUT ARE EXPECTED TO
DIP AGAIN INTO IFR AND POSSIBLY LIFR TONIGHT WITH REDEVELOPMENT OF
LOW CIGS.
TAX

.AVIATION /WEDNESDAY THROUGH SATURDAY/...
DUE TO THE LARGE AND SLOW MOVING UPPER LEVEL LOW PRESSURE SYSTEM...PERIODIC
RSTRNS COULD LAST THROUGH THURS IN SCATTERED SHRA.

&&

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

&&

$$





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