Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 191750
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
150 PM EDT TUE AUG 19 2014

.SYNOPSIS...
HIGH PRESSURE DRAPED FROM QUEBEC PROVINCE TO EASTERN NEW YORK WILL
SETTLE ACROSS NEW ENGLAND TODAY. WHILE THIS WILL CONTINUE TO PROVIDE
THE VAST MAJORITY OF WESTERN AND NORTH CENTRAL NEW YORK WITH DRY
WEATHER...INTERIOR PORTIONS OF THE SOUTHERN TIER AND FINGER LAKES
COULD SEE A SHOWER OR THUNDERSTORM THIS AFTERNOON AS MOISTURE BEGINS
STREAMING NORTHWARD INTO OUR REGION. MORE WIDESPREAD SHOWERS AND
THUNDERSTORMS ARE THEN EXPECTED WEDNESDAY AND THURSDAY AS A WARM
FRONT LIFTS INTO OUR REGION FROM THE OHIO VALLEY...THEN STALLS OUT.

&&

.NEAR TERM /THROUGH TONIGHT/...
SATELLITE IMAGERY THIS AFTERNOON SHOWING RATHER EXTENSIVE CUMULUS
FIELDS IN THE GENESEE VALLEY AND WESTERN FINGER LAKES WHERE A PLUME
OF DEEPER LOW LEVEL MOISTURE HAS ADVECTED NORTH OUT OF PA. THESE
AREAS WILL SEE A MIX OF CLOUDS AND LIMITED SUN FOR THE AFTERNOON. A
BRIEF PASSING SHOWER CANNOT BE RULED OUT WITHIN THIS PLUME OF DEEPER
MOISTURE...BUT IT APPEARS THE AXIS OF BEST LOW LEVEL CONVERGENCE HAS
SHIFTED JUST EAST OF OUR AREA FROM STEUBEN COUNTY INTO CENTRAL PA.
THIS SHOULD BE THE MAIN FOCUS FOR ANY SCATTERED SHOWERS THIS
AFTERNOON. WITH THIS IN MIND...HAVE REMOVED THE RAIN CHANCES FOR THE
INTERIOR SOUTHERN TIER AND FINGER LAKES THIS AFTERNOON AND EVENING.

ELSEWHERE SKIES WILL REMAIN MOSTLY SUNNY FOR THE BALANCE OF THE
DAY...EXCEPT FOR SOME MID LEVEL CLOUD SPILLING INTO THE WESTERN END
OF THE STATE BY LATE AFTERNOON.

THROUGH THE NEAR TERM PERIOD...ELONGATED HIGH PRESSURE EXTENDING
FROM QUEBEC PROVINCE TO EASTERN NEW YORK WILL DRIFT OUT ACROSS NEW
ENGLAND...WHILE THE NEXT MID LEVEL TROUGH AND ATTENDANT BROAD
SURFACE LOW SLIDES ACROSS THE WESTERN AND CENTRAL GREAT LAKES...WITH
THIS LATTER FEATURE SWINGING ITS WARM FRONT TOWARD OUR AREA FROM
THE OHIO VALLEY TONIGHT.

TONIGHT...EXPECT INITIALLY QUIET CONDITIONS TO GIVE WAY TO
INCREASING CLOUDS FROM WEST TO EAST WITH THE APPROACH OF THE WARM
FRONT...WITH THIS FEATURE EVENTUALLY BRINGING INCREASING CHANCES FOR
SOME SHOWERS TO FAR WESTERN NEW YORK OVERNIGHT. WITH THE INCREASING
CLOUD COVER AND A WARMER AND SOMEWHAT MORE HUMID AIRMASS IN
PLACE...TEMPERATURES WILL BE CONSIDERABLY MILDER THAN THOSE OF THE
PREVIOUS FEW NIGHTS...WITH OVERNIGHT LOWS RANGING FROM THE MID TO
UPPER 50S ACROSS THE NORTH COUNTRY TO THE LOWER AND MID 60S
ELSEWHERE.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
THIS WILL CERTAINLY BE AN UNSETTLED PERIOD...ESPECIALLY EARLY ON AS
SEVERAL INGREDIENTS WILL COME INTO PLACE TO GENERATE SOME WIDESPREAD
RAINS. THIS RAINFALL COULD BE LOCALLY SIGNIFICANT. ALONG WITH THE
WET WEATHER...IT WILL FINALLY FEEL MORE LIKE SUMMER AS TEMPERATURES
WILL AVERAGE ABOVE NORMAL WITH MODERATELY HIGH HUMIDITY.

THE MAIN DRIVING FORCE FOR THE INCLEMENT WEATHER WILL BE A BROAD
UPPER LEVEL LOW...THAT INITIALLY ON WEDNESDAY WILL BE SITUATED OVER
THE UPPER GREAT LAKES. A DIVERGENT UPPER LEVEL FLOW FOUND DOWNWIND
OF THIS FEATURE WILL COUPLE WITH SOME WEAK WARM ADVECTION TO PRODUCE
GENERAL ASCENT ACROSS ALL OF OUR FORECAST AREA...WITH AT LEAST ONE
GUIDANCE PACKAGE SUGGESTING ADDITIONAL LIFT FROM A COUPLED H25 JET.
THIS LIFT WILL BE FOUND WITHIN A VERY MOIST (PWAT APPROACHING 2")
AND CONDITIONALLY UNSTABLE AIRMASS...AND WITH SHORT MBE VECTORS ALSO
BEING ADVERTISED...THE POTENTIAL WILL BE IN PLACE FOR SOME LOCALLY
HEAVY RAIN. THE GREATEST RISK FOR THE MORE SIGNIFICANT RAIN WILL
COME IN ANY SLOW MOVING THUNDERSTORM THAT DEVELOPS...AS TALL THIN
CAPE PROFILES AND A `WARM` CONVECTIVE CLOUD DEPTH OF 10-15K FT
(FAVORABLE MICROPHYSICS FOR MORE EFFICIENT RAIN PRODUCTION) ARE
ANTICIPATED.

ALL OF THAT BEING SAID...AM NOT SURE IF THE MATURE CYCLONE OVER THE
UPPER GREAT LAKES WILL PUSH A STRONG ENOUGH OCCLUSION ACROSS OUR
REGION TO FOCUS THE EXPECTED PCPN. WILL INCREASE POPS TO CATEGORICAL
BUT ONLY FORECAST BASIN AVERAGE QPF OF A QUARTER TO A HALF INCH ON
WEDNESDAY BECAUSE OF THIS UNCERTAINTY. THE POTENTIAL WILL BE THERE
THOUGH FOR LOCALLY HIGHER AMOUNTS (>1 INCH). THIS RISK WILL BE
COVERED IN THE HAZARDOUS WEATHER OUTLOOK (HWO). WEDNESDAY WILL BE
WARM AND HUMID (AS ONE WOULD EXPECT WITH PWAT`S NR 2") WITH MAX
TEMPS GENERALLY IN THE MID-UPPER 70S IN THE WEST AND NR 80 EAST OF
ROC.

THE UPPER LEVEL LOW WILL OPEN UP INTO A BROAD LONGWAVE TROUGH OVER
THE LOWER GREAT LAKES WEDNESDAY NIGHT. WHILE THE LIFT FROM THE
DIVERGENT UL FLOW AND WARM ADVECTION WILL PUSH OFF TO THE EAST...
THERE WILL STILL BE ENOUGH LIFT UNDER THE BASE OF THE H5 TROUGH TO
PRODUCE SOME SHOWERS...WITH THE MOST WIDESPREAD ACTIVITY PUSHING
EAST OF ROCHESTER IN THE VCNTY OF THE SLOW MOVING SFC OCCLUSION.
WILL TIE THE POTENTIAL FOR HEAVY RAIN TO THIS FOCUSING BOUNDARY
WHILE RAISING POPS TO CATEGORICAL (HIGH CHC SW CORNER OF STATE) FOR
THE BULK OF THE FORECAST AREA. QPF WILL BE IN THE VCNTY OF 0.2 TO
0.4" WITH THE HIGHER AMOUNTS FOUND EAST OF THE GENESEE VALLEY. FOR
THE SECOND NIGHT IN A ROW...MERCURY READINGS WILL ONLY DROP INTO THE
LOW TO MID 60S.

ON THURSDAY...THE BASE OF THE H5 TROUGH WILL PUSH ACROSS THE
FORECAST AREA TO NEW ENGLAND ALONG WITH THE DEEPEST MOISTURE FIELD.
A HUMID...CONDITIONALLY UNSTABLE AIRMASS WILL REMAIN IN PLACE THOUGH
SO WILL CONTINUE TO CARRY LIKELY POPS FOR SHOWERS AND POSSIBLE
TSTORMS.

AS THE TROUGH MOVES EAST THURSDAY NIGHT...RIDGING OVER THE MID WEST
AND UPPER GREAT LAKES WILL BUILD TO THE EAST. THIS WILL ENCOURAGE
THE SHOWER ACTIVITY TO TAPER OFF FROM WEST TO EAST WITH ONLY CHC
POPS REMAINING IN PLACE.

FOR FRIDAY AND FRIDAY NIGHT...THE RIDGING WILL AMPLIFY TO OUR WEST
WITH BOTH THE GFS AND ECMWF SUGGESTING THAT SOME SUBTLE SHORTWAVES
WILL DROP SOUTHEAST ALONG A STRENGTHENING WARM FRONT. DEPENDING ON
THE TIMING OF THESE IMPULSES...THERE COULD BE SOME SHOWERS OVER THE
WESTERN COUNTIES. WILL KEEP LOW CHC POPS IN PLACE FOR FRIDAY WITH
SLGT CHC FRIDAY NIGHT UNTIL ADDITIONAL GUIDANCE ADDS SUPPORT TO THIS
SCENARIO.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
TEMPERATURES WILL AVERAGE A LITTLE ABOVE NORMAL DURING THIS PERIOD
AS AN AMPLIFYING RIDGE OVER THE UPPER GREAT LAKES IS FORECAST TO
EVENTUALLY `FOLD OVER` ACROSS NEW ENGLAND AND THE ST LAWRENCE
VALLEY. UNDER THIS H5 RIDGE...A WEAK DISTURBANCE WILL TRY TO PUSH A
WARM FRONT EASTWARD ACROSS THE LOWER GREAT LAKES. THIS WILL KEEP THE
POTENTIAL FOR SHOWERS...AT LEAST FOR THE WESTERN COUNTIES...IN PLACE
FOR MUCH OF THE PERIOD.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
A PLUME OF DEEPER LOW LEVEL MOISTURE ADVECTING NORTH OUT OF
PENNSYLVANIA WILL CONTINUE TO PRODUCE ENHANCED CUMULUS FIELDS
THROUGH LATE AFTERNOON FROM THE GENESEE VALLEY INTO THE FINGER
LAKES. MVFR CIGS ACROSS HIGHER TERRAIN SHOULD IMPROVE TO THE LOWER
END OF THE VFR CATEGORY BY LATE AFTERNOON AS DAYTIME MIXING REACHES
ITS MAX. THIS PLUME OF MOISTURE WILL GRADUALLY DIMINISH AS IT DRIFTS
INTO CENTRAL NY TONIGHT.

OTHERWISE MID LEVEL CLOUDS WILL THICKEN AND LOWER FROM WEST TO EAST
TONIGHT IN ADVANCE OF A WARM FRONT AND UPPER LEVEL DISTURBANCE. A
FEW SHOWERS WILL DEVELOP ACROSS WESTERN NY BY LATE TONIGHT AND
BECOME MORE WIDESPREAD THROUGHOUT THE REGION ON WEDNESDAY. EXPECT
CIGS/VSBY TO INITIALLY BE VFR...BUT MVFR WILL BECOME MORE LIKELY IN
THE HEAVIER SHOWERS ON WEDNESDAY AS THE LOW LEVELS SATURATE AND
SHOWER INTENSITY INCREASES. A FEW OF THE HEAVIEST SHOWERS MAY
PRODUCE BRIEF/LOCAL IFR CONDITIONS...BUT TIMING AND PLACEMENT OF
THESE LOWER CONDITIONS IS VERY UNCERTAIN AT THIS TIME RANGE.

OUTLOOK...
WEDNESDAY NIGHT AND THURSDAY...OCCASIONAL SHOWERS AND THUNDERSTORMS
WITH ATTENDANT LOCALIZED REDUCTIONS TO IFR/MVFR.
FRIDAY AND SATURDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND
THUNDERSTORMS.
SUNDAY...MAINLY VFR.

&&

.MARINE...
HIGH PRESSURE DRAPED FROM QUEBEC PROVINCE TO EASTERN NEW YORK WILL
SETTLE ACROSS NEW ENGLAND TODAY. A WARM FRONTAL BOUNDARY WILL THEN
LIFT INTO THE LOWER LAKES REGION ON WEDNESDAY AND LINGER THROUGH
THURSDAY...BEFORE GETTING SHUNTED SOUTHWARD AGAIN ON FRIDAY.
WHILE THE WARM FRONT WILL BRING OCCASIONAL SHOWERS AND THUNDERSTORMS
TO THE REGION WEDNESDAY AND THURSDAY...WINDS AND WAVES ARE EXPECTED
TO REMAIN BELOW ADVISORY LEVELS THROUGH THE END OF THE WORK WEEK.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...JJR
NEAR TERM...HITCHCOCK/JJR
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...HITCHCOCK
MARINE...JJR




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