Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 311435
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1035 AM EDT FRI JUL 31 2015

.SYNOPSIS...
HIGH PRESSURE RIDGED FROM THE OHIO VALLEY INTO NEW YORK STATE
WILL KEEP DRY AND QUIET WEATHER ACROSS OUR REGION THROUGH MOST OF
TODAY. A NUMBER OF DISTURBANCES PASSING THROUGH A BROAD UPPER
LEVEL TROUGH WILL THEN BRING PERIODIC OPPORTUNITIES FOR SCATTERED
SHOWERS AND THUNDERSTORMS FROM LATE THIS AFTERNOON AND EVENING
ONWARD INTO EARLY NEXT WEEK...THOUGH MUCH OF THE TIME WILL STILL
BE RAIN FREE.

&&

.NEAR TERM /THROUGH TONIGHT/...
VISIBLE SATELLITE IMAGERY SHOWING ABUNDANT SUNSHINE ACROSS THE
REGION LATE THIS MORNING WITH JUST ONE SMALL PATCH OF CIRRUS ACROSS
THE NIAGARA FRONTIER AND SOME DIURNAL CUMULUS STARTING TO DEVELOP
ACROSS THE HIGHER TERRAIN EAST OF LAKE ONTARIO. EXPECT NEARLY FULL
SUNSHINE THROUGH AT LEAST MID AFTERNOON BEFORE CUMULUS BEGIN TO
BECOME MORE PREVALENT ALONG AND INLAND FROM THE BOUNDARIES PRODUCED
BY THE GRADIENT ONSHORE FLOW OFF THE LAKES.

FOR MUCH OF TODAY...OUR REGION WILL REMAIN UNDER THE INFLUENCE OF
HIGH PRESSURE AND DRY AIR RIDGED FROM THE OHIO VALLEY INTO NEW
YORK STATE. THIS WILL RESULT IN FAIR/DRY WEATHER AND MOSTLY SUNNY
SKIES PERSISTING THROUGH THE BULK OF THE DAY...WITH 850 MB TEMPS
OF +14C TO +16C SUPPORTING WIDESPREAD HIGHS IN THE LOWER TO MID
80S. COUPLED WITH DEWPOINTS RANGING FROM THE MID 50S TO AROUND 60
AND A DECENT BREEZE...THIS WILL RESULT IN A PLEASANTLY WARM LAST
DAY OF JULY.

LATE THIS AFTERNOON AND TONIGHT...THE NEXT IN A SERIES OF
SHORTWAVE IMPULSES WILL ROUND THE BASE OF THE DEEPENING LARGE-
SCALE UPPER TROUGH ACROSS THE GREAT LAKES AND NORTHEAST...AND IN
THE PROCESS WILL PUSH INTO OUR REGION IN CONCERT WITH ITS
ATTENDANT WEAK SURFACE REFLECTION. AS THESE FEATURES BEGIN TO
IMPINGE UPON OUR AREA LATE THIS AFTERNOON...INCREASING
LIFT/MOISTURE ASSOCIATED WITH BOTH THESE AND A LAKE BREEZE
CONVERGENCE ZONE COULD TOUCH OFF A SHOWER/THUNDERSTORM OR TWO
ACROSS NIAGARA AND ORLEANS COUNTIES...FOR WHICH SOME LOW CHANCE
POPS REMAIN IN PLAY. BETTER AND MORE GENERAL OPPORTUNITIES FOR
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL THEN FOLLOW
FOR TONIGHT AS THE SHORTWAVE DIGS FURTHER INTO OUR REGION...WITH
CONVECTIVE COVERAGE MOST LIKELY TO PEAK DURING THE LATE EVENING
AND EARLY OVERNIGHT HOURS...THEN DIMINISH OVERNIGHT. AS FOR
TEMPS...OVERNIGHT LOWS ARE AGAIN EXPECTED TO RANGE FROM THE UPPER
50S ACROSS INTERIOR PORTIONS OF THE SOUTHERN TIER AND NORTH
COUNTRY TO THE LOWER AND MID 60S ELSEWHERE...WITH THE WARMEST
OVERALL TEMPS FOUND ALONG THE IMMEDIATE LAKESHORES.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
A SOMEWHAT AMPLIFIED UPPER LEVEL PATTERN WILL BE IN PLACE OVER
NORTH AMERICA DURING THIS PERIOD. BROAD TROUGHINESS OVER THE GREAT
LAKES WILL BE ANCHORED BY AN ANOMALOUSLY DEEP CLOSED LOW OVER
JAMES BAY... WHILE A STRONG SUB-TROPICAL RIDGE WILL BE CENTERED
OVER NEW MEXICO. THIS WILL KEEP OPPRESSIVE SUMMER HEAT OUT WEST
WHILE OUR REGION WILL EXPERIENCE TEMPERATURES THAT WILL AVERAGE
WITHIN A COUPLE DEGREES OF NORMAL.

IN TERMS OF RAINFALL...IMPULSES TRACKING SOUTHEAST FROM THE
CANADIAN PRAIRIES AND UPPER GREAT LAKES WILL BE CONDUCIVE FOR
PERIODIC SHOWER AND THUNDERSTORM ACTIVITY...BUT THE BULK OF THE
PERIOD WILL BE PCPN FREE. THE DEEP CYCLONIC FLOW WILL ESSENTIALLY
CUT OFF ANY GULF MOISTURE...AND WITHOUT ANY ORGANIZED SFC
FEATURES...PCPN WILL BE SCATTERED IN NATURE WITH GENERAL
INSIGNIFICANT QPF. THIS IS IMPORTANT TO NOTE AS PARTS OF WRN NEW
YORK HAVE RECEIVED LITTLE RAINFALL OVER THE PAST TWO WEEKS.

GETTING TO THE DETAILS... WHILE SATURDAY WILL BE LARGELY DRY
ACROSS THE REGION...A SHORTWAVE WILL TRACK SOUTHEAST FROM LAKE
HURON DURING THE MORNING HOURS AND CROSS TO OUR NORTH DURING THE
MIDDAY AND AFTERNOON. GIVEN THE DISCREPANCIES BETWEEN THE GUIDANCE
PACKAGES...THERE IS RELATIVELY LOW CONFIDENCE WITH THE TIMING OF
THIS FEATURE. THIS IS IMPORTANT IN THAT A SLOWER PASSAGE WOULD
ALLOW FOR INCREASED DIURNAL INSTABILITY AND THEREBY A GREATER
COVERAGE OF MIDDAY AND AFTERNOON CONVECTION. WILL FOLLOW
CONTINUITY...WHICH FAVORS CHC POPS FOR THE SECOND HALF OF THE DAY.
A SLOWER PASSAGE OF THE MID LEVEL FEATURE WOULD ALSO INCREASE THE
RISK FOR STRONG TO SEVERE CONVECTION. WHILE SBCAPES OF 1000-1500
J/KG STILL APPEAR POSSIBLE...AM LESS IMPRESSED WITH THE AMOUNT OF
SHEAR (BULK <30KTS) BEING EXPRESSED BY THE NEW GUIDANCE PACKAGE.
SPC ALSO LOOKS TO BE UNIMPRESSED AS THE AREA IS ONLY IN A GENERAL
RISK FOR THUNDERSTORMS. OTHERWISE THE VAST MAJORITY OF THE DAY
THOUGH WILL BE RAIN FREE. MAX TEMPS WILL GENERALLY RANGE FROM 75
TO 80...WITH THE HIGHER END OF THE RANGE BEING FOUND IN THE
GENESEE VALLEY AND ON THE LAKE PLAINS SOUTH OF LK ONTARIO.

IN THE WAKE OF THE DEPARTING MID LEVEL SHORTWAVE SATURDAY
EVENING... ANY RESIDUAL AFTERNOON CONVECTION WILL DIE OFF FAIRLY
QUICKLY WITH THE LOSS OF DAYTIME HEATING. THIS SHOULD LEAVE A
MAINLY DRY NIGHT ACROSS OUR REGION WITH TEMPERATURES SETTLING TO
NEAR 60 ACROSS THE LAKE PLAINS AND THE MID TO UPPER 50S EAST OF LK
ONTARIO AND ACROSS THE BULK OF THE SRN TIER.

SUNDAY SHOULD FEATURE GENERALLY FAIR WEATHER AND SLIGHTLY HIGHER
TEMPERATURES AS LOW LEVEL RIDGING WILL EXTEND ACROSS OUR REGION
FROM THE UPPER OHIO VALLEY. IT IS WORTH NOTING THOUGH THAT THE GFS
IS PAINTING A MUCH MORE UNSETTLED DAY. THE PROBLEM WITH THIS
SOLUTION THOUGH IS THAT IT STEMS FROM A SPURIOUS LOOKING AREA OF
CONVECTION THAT THE 00Z GFS GENERATES OVER THE CENTRAL PLAINS
SATURDAY EVENING...THEN TRACKS THE REMNANTS EAST ACROSS OUR REGION
FOR SUNDAY. WILL CONTINUE WITH OUR LOW CHC AFTERNOON POPS FROM
CONTINUITY...WHICH IS SUPPORTED BY THE ECMWF.

WHILE THERE WILL BE SEVERAL SHORTWAVES PASSING ACROSS OR JUST
NORTH OF OUR REGION DURING THIS PARTICULAR PERIOD...THE STRONGEST
IMPULSE IS FORECAST TO MOVE THROUGH OUR REGION MONDAY AFTERNOON OR
EVENING. THIS FEATURE WILL PUSH A FAIRLY STRONG COLD FRONT ACROSS
OUR REGION...BUT AS HIGHLIGHTED IN PREVIOUS DISCUSSIONS...THE MAIN
FORCING FOR CONVECTION MAY COME FROM A PRE-FRONTAL TROUGH. IN
EITHER CASE...HAVE BUMPED POPS TO HIGH CHC FOR THE SECOND HALF OF
MONDAY WHEN THE DEEPEST MOISTURE FIELD...JET INDUCED LIFT AND
DIURNAL INSTABILITY IS EXPECTED TO BE THE GREATEST. THE CONVECTION
WILL THEN WEAKEN AND DISSIPATE DURING THE COURSE OF MONDAY NIGHT
WHEN THE FRONT WILL PUSH TO OUR EAST.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
A GENERAL DEAMPLIFICATION OF THE LONGWAVE PATTERN IS EXPECTED
OVER NORTH AMERICA DURING THIS PERIOD...AS THE GFS AND ECMWF BASED
ENSEMBLES ARE SUGGESTING THAT THE ANOMALOUSLY DEEP CLOSED LOW
CENTERED NEAR JAMES BAY WILL OPEN UP AND PUSH OUT ACROSS FAR
EASTERN QUEBEC. MEANWHILE...EXPANSIVE SFC HIGH PRESSURE OVER THE
CANADIAN PRAIRIES WILL NOSE SOUTHEAST ACROSS THE UPPER GREAT LAKES
TO THE OHIO VALLEY. THIS SHOULD PROVIDE MAINLY FAIR DRY WEATHER
ACROSS OUR REGION...WITH THE CANADIAN BASED AIRMASS SUPPORTING
BELOW NORMAL TEMPERATURES. MAX TEMPS WILL BE IN THE 70S WHILE
OVERNIGHT LOWS WILL BE IN THE 50S.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
VFR WILL PREVAIL TODAY WITH CLEAR SKIES IN MOST AREAS.

LATE THIS AFTERNOON...THE NEXT IN A SERIES OF SHORTWAVE IMPULSES
WILL BEGIN TO IMPINGE UPON THE REGION. COUPLED WITH LIFT FROM A
LAKE BREEZE CONVERGENCE ZONE...THIS COULD TOUCH OF A SHOWER OR
THUNDERSTORM NEAR KIAG. THE SHORTWAVE WILL THEN PUSH DEEPER INTO
OUR REGION TONIGHT...BRINGING MORE GENERAL CHANCES FOR SCATTERED
TO NUMEROUS SHOWERS AND THUNDERSTORMS. ANY OF THESE WILL HAVE THE
POTENTIAL TO PRODUCE BRIEF/LOCALIZED REDUCTIONS IN CIG/VSBY...WITH
VFR CONDITIONS OTHERWISE PREVAILING.

OUTLOOK...
SATURDAY THROUGH MONDAY...MAINLY VFR WITH SCATTERED SHOWERS AND
THUNDERSTORMS.
TUESDAY...MAINLY VFR.

&&

.MARINE...
IN ADVANCE OF AN APPROACHING SURFACE TROUGH...A BRISK WEST-
SOUTHWESTERLY FLOW WILL REDEVELOP ON LAKE ERIE THIS AFTERNOON...
THEN WILL LINGER INTO THE EARLY EVENING HOURS. FOR THIS REASON...
A FRESH BATCH OF SMALL CRAFT ADVISORIES HAVE BEEN HOISTED FOR THE
NEARSHORE WATERS OF LAKE ERIE AND THE UPPER NIAGARA RIVER AND
BUFFALO HARBOR...WITH THE START AND END TIMES OF THESE AS OUTLINED
BELOW.

OTHERWISE...WINDS AND WAVES ARE MOSTLY EXPECTED TO REMAIN BELOW
ADVISORY LEVELS THROUGH THE FIRST HALF OF THE WEEKEND...THOUGH
LOCALLY STRONGER WINDS/HIGHER WAVES WILL BE POSSIBLE IN AND NEAR
ANY SHOWERS AND THUNDERSTORMS TONIGHT AND SATURDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM EDT
         SATURDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 PM EDT
         THIS EVENING FOR LEZ020.

&&

$$

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


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