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Area Forecast Discussion
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000
FXUS61 KPBZ 220124 AAB
AFDPBZ

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PITTSBURGH PA
924 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/...
930PM UPDATE...CONTINUE TO RELY ON LATEST SAT/RADAR IMAGES AND
LATEST HRRR MODEL RUN TO PUT TOGETHER POPS FOR THE OVERNIGHT.
SHOWER COVERAGE HAS BEEN SLOWLY DECREASING AS IT DRIFTS SOUTHWARD
OVER EASTERN THIRD OF MY FA. LOOKS TO BE A SMALL UPPER LEVEL WAVE
THAT IS DRIVING THE PRECIPITATION. TEMPS HAVE ALSO BEEN ADJUSTED
WITH LATEST LAMP NUMBERS.

PREVIOUS DISCUSSION...

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/...
NORTHWESTERLY AND NORTHERLY FLOW IN THE LOW AND MID LEVELS
CONTINUE THROUGH WEDNESDAY NIGHT AND INTO THURSDAY AS LOW LEVEL
SHEAR SLOWLY INCREASES. THIS SHOULD ALLOW FOR UNSTABLE UPSLOPE
FLOW SHOWERS TO SLOWLY WIND DOWN DURING THE PERIOD. SOME CLEARING
SHOULD START TO WORK ITS WAY FROM WEST TO EAST ACROSS THE AREA AS
LAYER MOISTURE SLOWLY PEELS OFF TO THE EAST AS WELL.

YESTERDAY'S GFS...AND NOW TODAY'S ECMWF AND GFS BOTH INDICATE A
SOMEWHAT ANOMALOUS LOOKING SHORT WAVE TRACKING SOUTHEASTWARD DOWN
THE FRONT FLANK OF THE UPPER RIDGE THAT BUILDS TOWARD THE AREA BY
LATE IN THE WEEK. DEEP MOISTURE DOES NO SEEM PARTICULARLY EVIDENT
WITH THIS SYSTEM...AND THE DEPTH OF THE SYSTEM IS NOT PARTICULARLY
WELL AGREED UPON. GIVEN THE FACT THAT THE GFS HAS BEEN A BIT MORE
CONSISTENT WITH THE FEATURE IN ITS RUNS...TIMING AND PLACEMENT
CLOSER TO THE GFS WAS FAVORED...WHICH WILL LIKELY ALLOW FOR AN
INCREASE IN CLOUDS LATE IN THE WEEK...AND A VERY VERY SLIGHT
CHANCE OF A FLEETING SPRINKLE. OTHERWISE...TEMPERATURES CONTINUE
THEIR SLOW TREND TO CREEP BACK TOWARD NORMAL. FRIES

&&

.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 /02Z WEDNESDAY THROUGH SUNDAY/...
ABUNDANT LOW LEVEL MOISTURE WILL KEEP THE REGION SOCKED IN WITH
CLOUDS THROUGH MOST OF THE TAF PERIOD. AS THE UPPER LEVEL LOW
SLOWLY ROTATES ACROSS...SCATTERED TO NUMEROUS LIGHT RAIN SHOWERS
WILL CONTINUE THROUGH MUCH OF THE NIGHT. MANY OF THESE WILL
CONCENTRATE ALONG THE RIDGES. MVFR TO IFR CONDITIONS ARE FORECAST
AREAWIDE INTO MIDMORNING ON WEDNESDAY. CIGS COULD IMPROVE TO VFR
BY LATE AFTERNOON ACROSS EASTERN OHIO AND WESTERN PA. WINDS WILL
GENERALLY BE OUT OF THE NORTH AND NORTHWEST.

.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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