Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 301431
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1031 AM EDT THU JUL 30 2015

.SYNOPSIS...
A DRIER AIRMASS WILL EXPAND ACROSS THE EASTERN GREAT
LAKES REGION THIS AFTERNOON AND THROUGH THE OVERNIGHT...PROVIDING
FOR MAINLY CLEAR SKIES AND MORE COMFORTABLE LEVELS OF HUMIDITY. AN
UPPER LEVEL TROUGH WILL SLIDE TOWARDS THE REGION BY FRIDAY EVENING
AND PRODUCE SCATTERED SHOWERS AND THUNDERSTORMS THAT WILL REMAIN
POSSIBLE THROUGH THE WEEKEND...THOUGH MUCH OF THE TIME WILL BE
RAINFREE.

&&

.NEAR TERM /THROUGH TONIGHT/...
LATE THIS MORNING A COLD FRONT
CONTINUES TO ADVANCE ACROSS THE REMAINDER OF THE CWA...WITH THE
FRONT AND ASSOCIATED RAIN SHOWERS NOW ACROSS OUR FAR EASTERN ZONES.
THE FRONT AND ITS SHOWERS WILL CLEAR THE CWA BY NOONTIME WITH A GOOD
DEAL OF SUNSHINE FOUND IN ITS WAKE.

STRONG DRYING AND SYNOPTIC-SCALE SUBSIDENCE SHOULD LEAD TO FAIRLY
RAPID CLEARING FROM WEST TO EAST...YIELDING A RETURN TO MOSTLY SUNNY
SKIES AREAWIDE BY EARLY AFTERNOON. THE COMBINATION OF THE RETURNING
SUNSHINE AND MODEST COOL AIR ADVECTION WILL ALLOW FOR GOOD MIXING TO
DEVELOP...WHICH IN TURN WILL LEAD TO THE DEVELOPMENT OF BREEZY
CONDITIONS...PARTICULARLY DOWNWIND OF THE LAKES WHERE SOME GUSTS TO
25-30 MPH WILL BE LIKELY THIS AFTERNOON. WITH THE GOOD MIXING AND
850 MB TEMPS REMAINING IN THE VICINITY OF +15C TO +17C INTO THIS
AFTERNOON...DAYTIME HIGHS WILL STILL MANAGE TO REACH THE LOWER TO
MID 80S IN MOST PLACES TODAY...THOUGH CONDITIONS WILL TURN
NOTICEABLY LESS HUMID AS DEWPOINTS DROP INTO THE UPPER 50S AND LOWER
60S.

TONIGHT...EXPECT FAIR AND DRY WEATHER ALONG WITH DIMINISHING
WINDS AS HIGH PRESSURE OVER THE TENNESSEE AND OHIO VALLEYS
CONTINUES TO RIDGE NORTHEASTWARD INTO OUR REGION. WITH A SOMEWHAT
COOLER AND LESS HUMID AIRMASS IN PLACE...NIGHTTIME LOWS WILL RANGE
FROM THE UPPER 50S ACROSS INTERIOR SECTIONS OF THE SOUTHERN
TIER/NORTH COUNTRY TO THE LOWER TO MID 60S ACROSS THE REST OF THE
REGION...WITH THE WARMEST READINGS FOUND ALONG THE IMMEDIATE
LAKESHORES.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
THE SUB TROPICAL RIDGE PREVIOUSLY CENTERED OVER TEXAS AND THE
LOWER MISSISSIPPI VALLEY WILL RETROGRADE TO NEW MEXICO AND THE
SOUTHERN ROCKIES DURING THIS PERIOD. MEANWHILE...A PHASED LONGWAVE
TROUGH WILL BE FOUND OVER THE LOWER GREAT LAKES AND EASTERN
CANADA. THIS WILL ESTABLISH A DEEP CYCLONIC FLOW OVER OUR FORECAST
AREA WITH MARGINALLY `COOLER` AIR EXPECTED. THE NEWSWORTHY HEAT
THAT HAS BEEN SO PREVALENT IN THE EAST WILL PUSH TO THE WESTERN
STATES.

WHILE DRY WEATHER WILL BE IN PLACE FOR OUR REGION FOR MUCH OF
THIS PERIOD...DIFFICULT TO TIME MID LEVEL DISTURBANCES CRUISING
SOUTHEAST INTO THE AFOREMENTIONED LONGWAVE TROUGH WILL GENERATE
SCATTERED SHOWERS AND POSSIBLE THUNDERSTORMS. WILL GENERALLY COVER
THIS ACTIVITY WITH CHC POPS AS THERE IS A FAIR AMOUNT OF
DISAGREEMENT EXPRESSED BETWEEN THE VARIOUS GUIDANCE PACKAGES.

A FAIRLY STRONG SHORTWAVE WILL CROSS THE UPPER GREAT LAKES DURING
THE DAY FRIDAY WHILE GENERAL SUBSIDENCE WILL BE FOUND ACROSS OUR
FORECAST AREA. THIS WILL SUPPORT DRY WEATHER FOR THE BULK OF THE
DAY...BUT AS WE GET DEEPER INTO THE AFTERNOON...A LINE OF
CONVECTION TRAILING SOUTH FROM THE MID LEVEL DISTURBANCE WILL
APPROACH THE IAG FRONTIER AND THOUSAND ISLANDS REGION.
TEMPERATURES FRIDAY WILL GENERALLY CLIMB INTO THE UPPER 70S TO
LOWER 80S.

THE MID LEVEL DISTURBANCE WILL TRACK BY TO OUR NORTH FRIDAY NIGHT
WHILE AN ASSOCIATED WEAK SFC FRONTAL BOUNDARY WILL PUSH ACROSS OUR
FORECAST AREA. THIS MAY VERY WELL BE OUR HIGHEST CHANCE FOR PCPN
DURING THIS PERIOD...AS THERE SHOULD BE ENOUGH FORCING WITHIN A
FAIRLY UNSTABLE AIRMASS TO GENERATE SCATTERED SHOWERS AND
THUNDERSTORMS. WHILE OUR REGION HAS DRIED OUT CONSIDERABLY DURING
THE PAST WEEK OR TWO...UNFORTUNATELY THIS BOUNDARY IS NOT EXPECTED
TO PRODUCE MORE THAN A TENTH OF AN INCH OF RAIN FOR MOST AREAS.

THE NEXT SHORTWAVE WILL TAKE AIM ON OUR REGION ON SATURDAY.
AGAIN... WHILE SCATTERED SHOWERS AND THUNDERSTORMS ARE
ANTICIPATED...THE MAJORITY OF THE DAY SHOULD BE RAIN FREE. ANY
CONVECTION WILL HAVE TO BE CLOSELY WATCHED THOUGH...AS A WEST TO
NORTHWEST FLOW ALOFT (NOTORIOUS FOR SUPPORTING STRONG TO SEVERE
STORMS BECAUSE OF THE RESULTING GREATER SHEARED ENVIRONMENT) WILL
BE IN PLACE. SUBSIDENCE AND LOW LEVEL RIDGING IN THE WAKE OF THE
EXITING SHORTWAVE WILL PROMOTE FAIR WEATHER WITH CLEARING SKIES
SATURDAY NIGHT.

WEAK LOW LEVEL RIDGING SHOULD BE ABLE TO SUPPORT GENERALLY DRY
WEATHER ON SUNDAY...BUT GIVEN THE CYCLONIC FLOW AND UNCERTAINTY OF
THE TIMING OF ADDITIONAL SHORTWAVES...AN AFTERNOON SHOWER OR
THUNDERSTORM CANNOT BE RULED OUT. TEMPERATURES ON SUNDAY SHOULD
TOP OUT WITHIN A FEW DEGREES OF 80.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
THE GENERAL LONGWAVE PATTERN OF HAVING A RIDGE IN THE WEST AND A
TROUGH IN THE EAST WILL REMAIN IN PLACE THROUGH AT LEAST THE MIDDLE
OF NEXT WEEK. THIS WILL KEEP TEMPERATURES CLOSE TO SEASONAL NORMALS
WITH HIGHS IN THE UPPER 70S TO LOWER 80S WHILE OVERNIGHT LOWS RANGE
FROM THE LOWER 60S MONDAY NIGHT TO THE 50S FOR TUESDAY AND WEDNESDAY
NIGHTS. IN TERMS OF RAINFALL...MORE SUBTLE SHORTWAVES ROTATING
THROUGH THE BASE OF THE TROUGH WILL ENCOURAGE ALTERNATING PERIODS OF
SHOWERS AND THUNDERSTORMS...ALTHOUGH FAIR DRY WEATHER SHOULD
DOMINATE THE PERIOD.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
AS OF 1130Z...THE SURFACE COLD FRONT NOW LIES ROUGHLY ALONG A
KROC-KDSV-KELZ LINE...WITH A NARROW BROKEN LINE OF SHOWERS AND A
FEW THUNDERSTORMS MARKING ITS PASSAGE PER AREA RADARS. THROUGH THE
REMAINDER OF THIS MORNING...THE FRONTAL BOUNDARY WILL FINISH
CROSSING THE BALANCE OF THE AREA FROM WEST TO EAST...WITH THIS
FEATURE AND ITS ASSOCIATED CONVECTION CLEARING OUR REGION
ALTOGETHER BY 16Z OR SO. SOME BRIEF REDUCTIONS IN FLIGHT
CONDITIONS TO IFR/MVFR WILL BE POSSIBLE WITHIN THIS ACTIVITY AS IT
PASSES ACROSS THE FINGER LAKES AND NORTH COUNTRY THIS MORNING...
OTHERWISE CONDITIONS WILL REMAIN PREDOMINANTLY VFR.

FOLLOWING THE PASSAGE OF THE COLD FRONT...VFR CONDITIONS ARE THEN
EXPECTED TO PREVAIL THROUGH THIS AFTERNOON AND TONIGHT...WITH
BREEZY CONDITIONS LATE THIS MORNING AND THIS AFTERNOON GIVING WAY
TO LIGHTER WINDS BY THIS EVENING.

OUTLOOK... FRIDAY THROUGH MONDAY...MAINLY VFR WITH ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS.

&&

.MARINE...
A WEAK COLD FRONT WILL FINISH CROSSING THE REGION THIS MORNING
ALONG WITH A BROKEN BAND OF SHOWERS AND THUNDERSTORMS. LOCALLY
HIGHER WINDS AND WAVES WILL BE POSSIBLE WITHIN/NEAR ANY
CONVECTION...WITH RELATIVELY BENIGN CONDITIONS PREVAILING
ELSEWHERE.

FOLLOWING THE PASSAGE OF THE COLD FRONT...A BRISK WESTERLY FLOW
WILL SET UP ACROSS LAKE ERIE AND EASTERN PORTIONS OF LAKE
ONTARIO/ADJOINING PORTIONS OF THE SAINT LAWRENCE RIVER...RESULTING
IN ADVISORY-LEVEL CONDITIONS IN THESE AREAS. FOR THIS
REASON...SMALL CRAFT ADVISORIES REMAIN IN EFFECT AS OUTLINED
BELOW.

AFTER THAT...HIGH PRESSURE OVER THE OHIO AND TENNESSEE VALLEYS
WILL GRADUALLY RIDGE NORTHEASTWARD TOWARD THE LOWER LAKES TONIGHT
AND FRIDAY...RESULTING IN A MODEST SOUTHWESTERLY TO WESTERLY FLOW
THAT SHOULD GENERALLY REMAIN BELOW ADVISORY LEVELS. THE ONE
EXCEPTION TO THIS MAY BE ON LAKE ERIE DURING FRIDAY...WHEN WINDS
AND WAVES MAY AGAIN APPROACH OR REACH LOWER-END ADVISORY CRITERIA.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT FRIDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR
         LEZ020.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
         LOZ045.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
         SLZ022.

&&

$$

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


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