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Area Forecast Discussion
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000
FXUS61 KPBZ 211833
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
233 PM 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 WEDNESDAY/...
IMPRESSIVE CIRCULATION PRESENT ON CURRENT RADAR AS A DECAYING LOW-
TOPPED MCV HAS STALLED NEAR JEFFERSON COUNTY PA. DESPITE ENHANCED
RADAR REFLECTIVITIES ALONG THE NRN EDGE OF THE 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...WITH
FREEZING LEVELS RIGHT AROUND 7KFT. 

LATEST WATER VAPOR IMAGERY SHOWS ANOTHER SW TROF SWINGING SOUTH
THROUGH OHIO WITH AN ATTENDANT VORT MAX THROUGH SRN OHIO. THIS
GENERATED LAKE ENHANCED RAIN SHOWERS OVER THE SRN SHORE OF LAKE
ERIE THAT HAVE SINCE DE-TATCHED FROM THE LAKE AND HAVE CONGEALED WITH
THE BACK EDGE OF THE AFOREMENTIONED CIRCULATION. THIS VORT WILL
EFFECTIVELY CUT-OFF THE UPPER LOW AND ALLOW IT TO DRIFT RIGHT
OVERTOP OF US. WITH COPIOUS AMOUNTS OF LLVL MOISTURE AND THE COLD
POOL ALOFT...FURTHER DEVELOPMENT OF CONVECTIVELY DRIVEN RAIN
SHOWERS ARE EXPECTED EAST OF LAKE-ENHANCED AXIS OF RAIN SHOWERS. 

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 NIGHT 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 TUESDAY/...
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 /18Z TUESDAY THROUGH SUNDAY/...
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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