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Area Forecast Discussion
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000
FXUS61 KPBZ 300145
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
945 PM EDT MON SEP 29 2014

.SYNOPSIS...
WEAK LOW PRESSURE WILL CROSS THE REGION TUESDAY. WARM AND DRY
CONDITIONS WILL FOLLOW UNTIL THE PASSAGE OF A FRIDAY COLD FRONT.

&&

.NEAR TERM /THROUGH TUESDAY/...
ADJUSTMENTS TO SKY AND TEMPS BASED ON STLT TRENDS/SFC OBS FOR THE
LT EVE UPDT. PREVIOUS DISC...DRY WEA IS EXPD TNGT AS A WK MID/UPR
TROF EXITS. THE NXT ADVNG SHRTWV WL MOVE ACRS THE GT LKS RGN TUE
WITH SCT SHWRS. LACK OF DEEP MOISTURE AND THE RECENT DRY PATTERN
SHOULD HELP LMT PCPN COVG...SO MAINTAINED ONLY CHC POPS ATTM.
LATEST MDL PROGS SHOW VRY LTL INSTBY SO REMOVED TSTM MENTION FM
THE FCST. TEMPS WL CONT A FEW DEG ABV SEASONAL LVLS.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
MODELS MORE OR LESS AGREE ON FRONTAL TIMING TUESDAY NIGHT...WITH THE 
BOUNDARY NEAR OR THROUGH PIT BY 00Z. WITH CONTINUING FROPA...WILL
KEEP FADING CHANCE POPS IN THE FORECAST WITH THE LIMITED
MOISTURE...LIKELY TOO LITTLE TO TAKE MUCH ADVANTAGE OF THE ARRIVAL
OF UPPER CLOSED LOW DURING THE NIGHT. HAVE DRY POPS BY SUNRISE ON
WEDNESDAY. COULD SEE SOME PATCHES OF LOW CLOUD FORM UP DURING THE
NIGHT...WHICH WOULD KEEP TEMPERATURES UP. BLENDED MOS GUIDANCE
INTO PREVIOUS MIN TEMP GRID TO NUDGE VALUES UP A DEGREE OR TWO.

AS HINTED AT BY PREVIOUS SHIFT...WENT AHEAD AND ADDED A MINIMAL POP 
FOR SHRA TO THE EASTERN RIDGES FOR WEDNESDAY AFTERNOON.  UPPER LOW 
ALONG WITH ITS COLD POOL ALOFT WILL STILL BE EXITING DURING TIME OF 
PEAK HEATING.  WHILE THERE IS ENOUGH MIDLEVEL WARM AIR TO PREVENT 
SHRA FORMATION FROM PIT ON WEST...BUFKIT SOUNDINGS SHOW A BIT MORE 
FAVORABLE CAPE PROFILE FOR LOCATIONS LIKE DUJ AND LBE. TO THE 
WEST...ANY MORNING LOW CLOUDS WOULD LIFT INTO SCT CU ONLY.  USED NAM 
H850 TEMPS TO CONSTRUCT MAX TEMP GRID...ENDING UP WITH VALUES CLOSE 
TO MOS.

ONCE UPPER LOW EXITS...WEAK SURFACE HIGH PRESSURE AND H500 RIDGING 
BUILD IN...GIVING US DRY WEATHER FOR WEDNESDAY NIGHT AND THURSDAY.  
MAY SEE A FEW MORE CLOUDS ALONG THE EASTERN RIDGES THAN THE WEST 
GIVEN SOME LIGHT EAST/SOUTHEAST FLOW.  TEMPERATURES WILL CONTINUE TO 
RUN ABOVE NORMAL.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
ECMWF COMING A LITTLE MORE IN LINE WITH GFS AND ENSEMBLES ON TIMING 
OF MORE SIGNIFICANT FROPA ON FRIDAY.  GIVEN INCREASED 
CONFIDENCE...BUMPED POPS UP TO LIKELY AND ALSO INSERTED A CHANCE OF 
THUNDER WITH THE VIGOROUS NATURE OF THE SYSTEM. SOME DISAGREEMENT
THEREAFTER WHETHER ANOTHER CLOSED LOW SINKS IN BEHIND THE FRONT.
WILL RIDE WITH THE PREVIOUS FORECAST FROM SATURDAY ON FOR NOW. IN
ANY CASE...MUCH COOLER AIR ARRIVES FOR THE WEEKEND.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
THE ONLY BLEMISH ON VFR CONDITIONS THROUGH DAYBREAK TUESDAY IS
EXPECTED TO COME FROM FM SHALLOW PREDAWN FOG. SHOULD MID LVL
CLDINESS DVLP A FEW HRS QUICKER THAN ANTICIPATED WITH THE ADVN OF
THE AFOREMENTIONED SHRTWV...THAT RESTRICTION POTENTIAL WL BE
PRECLUDED.

OTHERWISE...SCT SHWRS ARE EXPECTED TO DVLP WITH THE DISTURBANCE...BUT
RESTRICTION POSSIBILITY LKS TO BE LTD TO SOME MVFR VSBYS.

OUTLOOK.../TUESDAY THROUGH FRIDAY/...
THE NXT CHC FOR WIDESPREAD RESTRICTION WL COME WITH A FRIDAY CDFNT.

&&

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

&&

$$

07/15





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