341
FXUS61 KPBZ 090247
AFDPBZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PITTSBURGH PA
1047 PM EDT THU JUN 8 2023
SYNOPSIS
THERE IS A LOW PROBABILITY OF DAYTIME SHOWERS NORTHEAST AND EAST
OF THE PITTSBURGH METRO FRIDAY AFFILIATED WITH AN UPPER LOW.
DRY, SEASONABLE WEATHER IS EXPECTED SATURDAY BEFORE
INTERMITTENT RAIN CHANCES RETURN NEXT WEEK WITH A PATTERN
CHANGE.
NEAR TERM /THROUGH FRIDAY/
WEAK SHORTWAVES WILL CONTINUE TO TRAVERSE THE WEST SIDE OF AN UPPER
LOW PRESSURE CENTERED OVER THE UPPER NEW ENGLAND REGION THROUGH
FRIDAY. MODEST MID-LEVEL MOIST AND VORT ADVECTION MAY ALLOW FOR
AN ISOLATED SHOWER AROUND NORTHWEST PA OVERNIGHT, BUT NOCTURNAL
INVERSIONS SHOULD KEEP THE REGION DRY. OVERNIGHT LOW TEMPERATURE
WILL FALL 5 TO 10 DEGREES BELOW NORMAL AS FALLING PRESSURE
HEIGHTS AND WEAK COLD ADVECTION SOMEWHAT OFFSET THE WARMING
EFFECT OF INCREASED CLOUD COVER.
AS ANOTHER SHORTWAVE CROSSES THE UPPER OHIO RIVER VALLEY FRIDAY,
THE ENVIRONMENT WILL BECOME MORE FAVORABLE FOR SHOWER AND
ISOLATED THUNDERSTORM ACTIVITY GIVEN INCREASED SHEAR AND FURTHER
COOLING OF MID-LEVEL AIR TO CREATE SOME SEMBLANCE OF
INSTABILITY. HOWEVER, CLOUD COVER WILL LIMIT SURFACE HEATING
(DAYTIME HIGHS WILL REMAIN SEASONABLY COOL) AND KEEP
INSTABILITY TO A MINIMA, WHILE LITTLE CHANGE TO THE NEAR- SFC
DRY LAYER AND MOISTURE DEPTH WILL LIMIT QPF OUTPUT WITH THE
ISOLATED/SCATTERED SHOWERS THAT DEVELOP. LOCALES FAVORED FOR AN
AFTERNOON SHOWER WILL BE NORTH AND EAST OF PITTSBURGH, WITH THE
PROBABILITY OF SEEING GREATER THAN 0.10 INCHES OF RAIN SITTING
AT LESS THAN 40 PERCENT.
THE POTENTIAL FOR AIR QUALITY ISSUES REMAIN A CONCERN AS THE
PATTERN GOES UNCHANGED AND CAN STILL DRAW WILDFIRE SMOKE TO THE
REGION. PLEASE SEE YOUR LOCAL DEP FOR THE LATEST INFORMATION AND
AIR QUALITY ALERTS FOR YOU AREA.
SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/
SUBSIDENCE AND SFC RIDGING WILL RETURN DRY WEATHER FORECASTS TO
THE REGION FRIDAY NIGHT INTO SATURDAY AS THE NEW ENGLAND LOW
FINALLY BEGINS TO SHIFT EAST. RISING PRESSURE HEIGHTS ALOFT AS
NORTHWEST FLOW WEAKENS IN RESPONSE TO THE DEPARTING LOW WILL
PROMOTE TEMPERATURE MODERATION AS WELL FOR SATURDAY. EXPECT MORE
SEASONABLE AFTERNOON TEMPERATURE AMID INCREASED INSOLATION. THIS
PATTERN SHIFT WILL ALSO SERVE TO CUT OFF THE WILDFIRE SMOKE
FETCH AND LIKELY END THE CURRENT STRING OF DAYS WITH AIR QUALITY
ISSUES.
QUASI-ZONAL FLOW WILL DEVELOP BY SATURDAY NIGHT OVER THE REGION
AS A DEVELOPING TROUGH/LOW DEEPENS OVER THE NORTHERN MISSISSIPPI
RIVER VALLEY. A STREAM OF CIRRUS CONNECTED TO WARM/MOIST
ADVECTION ALOFT IN ADVANCE OF THIS SYSTEM WILL MOVE OVER THE
FORECAST AREA, MODERATING OVERNIGHT TEMPERATURE TOWARDS
SEASONABLE LEVELS.
LONG TERM /SUNDAY THROUGH THURSDAY/
THE AFOREMENTIONED TROUGH IS EXPECT TO DROP OUT OF CENTRAL
CANADA DURING THE DAY ON SATURDAY AND BECOME A DEEPENING WESTERN GREAT
LAKES CUT OFF LOW ON SUNDAY. SOUTHWESTERLY FLOW AHEAD OF THE
TROUGH AXIS WILL FOSTER WARM, MOIST ADVECTION SUNDAY AND RAISE
AREA TEMPERATURE ABOVE NORMAL. AT THIS TIME, THE LOCATION OF
THE LOW TO THE WEST SHOULD KEEP SUNDAY MOSTLY DRY, IN PART DUE
TO WARM-AIR CAPPING ALOFT AND POSITIONING OF JET ASCENT. PRE-
FRONTAL CONVERGENCE MAY RESULT IN A FEW SHOWERS OVERNIGHT
SUNDAY, BUT THE SURFACE WARM AND COLD FRONT, ALONG WITH THE BEST
CHANCES OF PRECIPITATION, ARE NOT EXPECTED TO CROSS UNTIL
MONDAY. THIS TIMING FOLLOWS THE TREND OF SLOWER PROGRESSION OF
THE UPPER AND SURFACE LOW. PROBABILISTIC QPF THROUGH 12Z TUESDAY
RANGES FROM AROUND A THIRD OF AN INCH ON THE LOW END TO AROUND
ONE AND A HALF INCHES ON THE HIGH END.
THERE IS MODERATE CONFIDENCE THE UPPER LOW WILL SIT NEARBY
THROUGH MID WEEK, INTRODUCING INTERMITTENT PRECIPITATION CHANCES
WITH PASSING SHORTWAVES IN SOUTHWEST FLOW. THE UPPER LOW WILL
LIKELY DEPART BY LATE WEEK.
AVIATION /03Z FRIDAY THROUGH TUESDAY/
CLOUDS WILL CONTINUE TO FILTER THROUGH THE REGION OVERNIGHT AS
MOISTURE WITHIN AN UPPER-LVL LOW REMAINS CENTERED OVER THE
NORTHEAST. HOWEVER, VFR CONDITIONS WILL LIKELY PREVAIL WITH LITTLE
MOISTURE IN THE BOUNDARY LAYER. HAZE, FROM WILDFIRE SMOKE DIRECTED
SOUTH FROM QUEBEC, MAY LINGER ACROSS THE REGION BUT WILL LIKELY
BE NO LOWER THAN 6SM.
SHOWERS MAY DEVELOP FOR SITES EAST/SOUTHEAST OF PIT FRIDAY AFTERNOON
(AFTER 18Z) WITH AN EMBEDDED SHORTWAVE WITHIN AN UPPER-LVL LOW.
HOWEVER, IMPACTS TO ANY SITES WILL BE BRIEF; PROBABILITIES ARE
HIGHER FOR PIT/AGC/MGW/LBE BETWEEN 18Z AND 23Z FOR SHOWER
ACTIVITY.
OUTLOOK
ANY LINGERING HAZE/SMOKE WILL LIKELY CLEAR FROM THE REGION SATURDAY
WITH A CHANCE IN THE UPPER LEVEL PATTERN. RESTRICTIONS IN MUCH-
NEEDED WIDESPREAD RAINFALL ARE POSSIBLE BY SUNDAY AND MONDAY.
CLIMATE
PROLONGED DRY CONDITIONS HAVE RESULTED IS SIZABLE DRY STREAKS
AT SOME OBSERVING SITES. THE LONGEST CONSECUTIVE DAYS WITHOUT
MEASURABLE PRECIP AND CURRENT STREAKS ARE (AS OF JUNE 7TH):
CLIMATE SITE RECORD STREAK CURRENT STREAK
____________________________________________________________
PITTSBURGH 26 DAYS, 1874 18 DAYS
DUBOIS 23 DAYS, 1988 18 DAYS
ZANESVILLE 44 DAYS, 1963 18 DAYS
NEW PHILADELPHIA 27 DAYS, 1963 18 DAYS
WHEELING 27 DAYS, 1947/1884 18 DAYS
MORGANTOWN 36 DAYS, 1908 4 DAYS
PBZ WATCHES/WARNINGS/ADVISORIES
PA...NONE.
OH...NONE.
WV...NONE.
SYNOPSIS...MILCAREK
NEAR TERM...FRAZIER
SHORT TERM...FRAZIER
LONG TERM...MILCAREK
AVIATION...HEFFERAN/88
CLIMATE...MILCAREK
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