Area Forecast Discussion
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000
FXUS61 KPBZ 301349
AFDPBZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
949 AM EDT WED JUL 30 2014

.SYNOPSIS...
ANOTHER WEAK DISTURBANCE WILL MOVE THROUGH THE REGION THIS
AFTERNOON WITH SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS.
TEMPERATURES WILL BEGIN TO MODERATE TOWARD SEASONAL AVERAGES
BY LATE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
MID MORNING UPDATE TO ADJUST POPS BASED ON LATEST RADAR TRENDS.
MORNING SOUNDING STILL SUPPORT ISOLATED THUNDER AND BULK OF
FORECAST UNCHANGED. PREVIOUS DISCUSSION BELOW.


SHOWER AND THUNDERSTORM ACTIVITY BEGINNING TO INCREASE SPATIALLY
AND IN INTENSITY OVER THE SRN SHORES OF LAKE ERIE THIS MORNING.
THESE SHOWERS ARE IN RESPONSE TO A SHORT WAVE TROF DROPPING SOUTH
THROUGH THE GREAT LAKES CURRENTLY. THIS QUICK MOVING DISTURBANCE
WILL CONTINUE TO GENERATE SCATTERED SHOWERS TODAY AS IT PIVOTS
AROUND THE EXPANSIVE LOW PRESSURE SYSTEM STILL RESIDING NEAR JAMES
BAY. STEEPENING LLVL LAPSE RATES AND DEEPER MOISTURE AVAILABILITY
WILL HELP FUEL CONVECTIVE SHOWER DEVELOPMENT.

WHILE INSTABILITY IS STILL PRETTY LACKLUSTER WITH BUFR PROFILES SHOWING
TALL SKINNY CAPE...CURRENT RADAR TRENDS SHOWING VIGOROUS ENOUGH
CONVECTION TO GENERATE LIGHTNING. LIGHTNING COUNTS SHOULD
GENERALLY DECREASE AS THESE SHOWERS/THUNDERSTORMS MOVE FURTHER
INLAND AND ENCROACH THE CWA...BUT CANNOT RULE OUT A COUPLE OF
RUMBLES OVER OUR AREA. WILL INCLUDE THE MENTION OF ISOLATED
THUNDER IN THE FORECAST.

SHOWER CHANCES WILL DISSIPATE QUICKLY THIS EVENING AS THE WAVE
PULLS AWAY TOWARDS SUNDOWN. SEVERAL HI-RES MODELS INDICATING A
SECONDARY WAVE OF PRECIPITATION OVERNIGHT INTO THURS MORNING
ASSOCIATED WITH ANOTHER UPPER LEVEL TROF AXIS SWINGING THROUGH.
THIS FEATURE IS CORROBORATED AMONG THE MORE BROAD SOLNS OF THE 00Z
NAM AND GFS. THE DEEPER MOISTURE WILL REMAIN CLOSE TO THE UPPER
LOW ACROSS OUR NORTH...THIS WILL BE THE AREA THAT IS THE FOCUS OF
SLGT AND CHC POPS THROUGH ABOUT 12Z.
TAX

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
THE LONGWAVE WILL PIVOT EAST AND WEAKEN AS THE MAIN JET CORE
MIGRATES FURTHER BEYOND INFLECTION POINT OF THE FRONT SIDE OF THE
TROUGH AS A SECOND WEAK SHORTWAVE TRANSITIONS THROUGH THE FLOW
THURSDAY MORNING/EARLY AFTERNOON. THIS DISTURBANCE SHOULD ONLY
IMPACT NORTHERN ZONES AS THE LONGWAVE LIFTS TO THE NORTH.

FLOW ALOFT WILL SWITCH TO THE SOUTHWEST ON FRIDAY AND ALLOW FOR DEEPER
MOISTURE TO ADVECT NORTH. THIS ALONG WITH A SHORTWAVE PASSING
ACROSS THE REGION ON FRIDAY WILL RESULT IN SCATTERED
SHOWERS/THUNDERSTORMS FRIDAY AFTERNOON AND EARLY EVENING...WITH
THE BEST CHANCES ACROSS THE RIDGES AND SOUTHEASTERN PORTIONS OF
THE FORECAST AREA WHERE THERE WILL BE BETTER UPPER LEVEL SUPPORT.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
MOISTURE ADVECTION WILL CONTINUE OVERNIGHT FRIDAY AND SATURDAY BUT
RECENT MODEL RUNS HAVE NOT SHOWN THE BEST CONTINUITY IN REGARDS TO
TIMING THE NEXT SHORTWAVE TO PASS THROUGH AND HELP SUPPORT
ACTIVITY SO HAVE OPTED TO LEAVE CHANCE POPS IN THE FORECAST FOR
BOTH SATURDAY AND SUNDAY AFTERNOONS UNTIL GUIDANCE SHOWS BETTER
RUN TO RUN CONTINUITY WITH THE FEATURE. DRY CONDITIONS ARE
FORECAST BY NEXT MONDAY AS OPERATIONAL RUNS SHOW THE LONGWAVE
PATTERN BECOMING MORE ZONAL...BUT REMAIN CAUTIOUSLY OPTIMISTIC IN
FINALLY BREAKING THE PATTERN AS MODELS HAVE BEEN FAIRLY
INCONSISTENT IN PROGGING THIS OVER THE PAST 10 OPERATIONAL RUNS.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
A DISTURBANCE CURRENTLY DROPPING SOUTHWARD OUT OF THE GREAT LAKES
WILL INCREASE CLOUD COVER THIS MORNING. GENERALLY CONDITIONS
SHOULD STAY WELL WITHIN VFR FOR MOST PORTS THIS AFTERNOON. THE
EXCEPTION WILL BE AT FKL AND DUJ WHERE MVFR CIGS WITH SHOWERS ARE
POSSIBLE WITH THE PASSAGE OF A WEAK SURFACE BOUNDARY. SHOWERS
WILL QUICKLY END THIS EVENING...BUT ANOTHER WEAK WAVE PASSES LATE
TONIGHT AND THURSDAY MORNING WITH ADDITIONAL LIGHT SHOWER
CHANCES.

OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/...
NO WDSPRD RSTRNS EXPD.

&&

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

&&

$$









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