Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 130555
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
155 AM EDT SUN JUL 13 2014

.SYNOPSIS...
HUMID AND STORMY WEATHER IS EXPECTED SUNDAY AS A WARM FRONT LIFTS
ACROSS THE REGION QUICKLY FOLLOWED BY A COLD FRONT WITH A POTENTIAL
FOR STRONG TO SEVERE THUNDERSTORMS. THE COLD FRONT WILL THEN CROSS
THE LOWER GREAT LAKES SUNDAY NIGHT...HOWEVER THE CONTINUED PRESENCE
OF AN UPPER LEVEL TROUGH WILL KEEP A CHANCE FOR A FEW SHOWERS AND
THUNDERSTORMS INTO TUESDAY WHEN A STRONGER COLD FRONT MOVES
THROUGH...USHERING IN COOLER AND DRIER CONDITIONS FOR THE SECOND
HALF OF THE WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 06Z...REGIONAL RADAR IMAGERY SHOWS A MODEST BAND OF SHOWERS
LIFTING NORTHEAST ACROSS SOUTHERN ONTARIO IN ASSOCIATION WITH AN
APPROACHING WARM FRONT. ON ITS CURRENT TRAJECTORY...THE SOUTHERNMOST
PORTION OF THE BAND MAY CLIP PARTS OF THE NIAGARA FRONTIER AND LOWER
GENESEE VALLEY PRIOR TO SUNRISE. BEHIND THIS...CONDITIONS ARE DRY
ALL THE WAY UPSTREAM TO CENTRAL LOWER MICHIGAN...WHERE A LARGER BAND
OF SHOWERS AND EMBEDDED THUNDERSTORMS CONTINUES TO PRESS EASTWARD.
WHILE THIS SECOND AREA SHOULD WEAKEN SOME OVERNIGHT AS IT PRESSES
INTO PROGRESSIVELY MORE STABLE AIR...IT SHOULD STILL HOLD TOGETHER
ENOUGH TO REACH FAR WESTERN NEW YORK IN THE 10Z-12Z TIME FRAME
JUDGING FROM CURRENT RADAR TRENDS...BEFORE BODILY PUSHING EAST
ACROSS THE AREA DURING THE MORNING.

BASED ON ALL OF THE ABOVE...HAVE DROPPED POPS BACK TO LOW CHANCE OR
BELOW FOR THE REMAINDER OF THE NIGHT...AND HAVE PUSHED BACK THE
ARRIVAL OF THE SECOND AREA OF SHOWERS/EMBEDDED THUNDER BY SEVERAL
HOURS FROM EXISTING CONTINUITY.

WHILE THE INITIAL ROUND OF CONVECTION SUNDAY MORNING WILL LIKELY BE
ELEVATED AND NON-SEVERE...CONVECTION LATER IN THE DAY WILL LIKELY BE
ROOTED NEAR THE SURFACE AS AT LEAST MODEST SURFACE BASED INSTABILITY
DEVELOPS INLAND FROM THE LAKE SHADOWS.

THIS SECOND ROUND OF CONVECTION EXPECTED TO DEVELOP DURING THE
AFTERNOON HOURS AS MODEST HEATING BEHIND THE MORNING SHOWERS ALLOWS
SBCAPE TO PUSH TOWARDS 1000J/KG IN A MOISTURE RICH ENVIRONMENT. THE
DRIVING FACTOR BEHIND THIS SECOND ROUND WILL BE THE APPROACH OF A
WEAKENING COLD FRONT COINCIDENT WITH THE PASSAGE OF A MID-LEVEL
TROUGH...AS WELL AS LOCAL CONVERGENCE ZONES FROM STRONGER FLOW
CHANNELING DOWN LAKE ERIE...TERRAIN INDUCED CONVERGENCE...AND
DIFFERENTIAL HEATING BOUNDARIES. STRONG SHEAR PROFILES...
PARTICULARLY IN THE 0-3KM LAYER...EXACERBATED BY THE STRENGTH OF THE
LOW LEVEL JET WILL ELEVATE THE RISK FOR SEVERE WEATHER ACROSS THE
AREA...CONDITIONAL ON WHETHER ENOUGH SURFACE BASED INSTABILITY IS
ABLE TO DEVELOP BEHIND THE INITIAL SHOWERS. THE GREATEST CHANCE FOR
SEVERE WEATHER APPEARS TO BE DURING THE AFTERNOON FROM THE INTERIOR
SOUTHERN TIER INTO THE FINGER LAKES AND CENTRAL NY ALONG THE EASTERN
EDGE OF STRONGER CHANNELLED FLOW EMANATING FROM LAKE ERIE. THIS
SCENARIO IS SUPPORTED BY SEVERAL MESOSCALE MODELS...INCLUDING HIGHER
RESOLUTION CONVECTION ALLOWING ARW AND NMM VERSIONS OF THE WRF. THUS
HAVE ADDED GUSTY WIND ENHANCED WORDING TO THE FORECAST TO GO WITH
THE CONTINUING HEAVY RAIN THREAT BROUGHT ABOUT BY 1.75"+ PWATS.

OF PARTICULAR CONCERN IS THE NAM FORECAST AND OTHER MESOSCALE MODEL
GUIDANCE THAT HINTS AT AN MCV CROSSING THE AREA TOMORROW DURING THE
DAY. THIS WOULD EXACERBATE SAID SHEAR PROFILES...AND GIVEN THE
STRONG VEERING IN THE LOW LEVEL PROFILES..FURTHER ELEVATE THE SEVERE
RISK ACROSS THE AREA. BEFORE BUYING OFF COMPLETELY ON THAT FORECAST
HOWEVER...WOULD LIKE TO SEE IF UPSTREAM CONVECTION MATERIALIZES OVER
THE MIDWEST AND ACTUALLY FORCES THIS MCV TO DEVELOP.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
SUNDAY NIGHT SHOWERS AND THUNDERSTORMS WILL CONTINUE...MAINLY ACROSS
EASTERN AND SOUTHERN SECTIONS OF THE CWA AS A CONVECTIVE SHORTWAVE
AND ITS ASSOCIATED LIFT RIDES EASTWARD. HEAVY DOWNPOURS ARE STILL
LIKELY INTO THE EARLY EVENING HOURS WITH A MOIST AIRMASS. THERE WILL
STILL BE A RATHER STRONG LLJ ASSOCIATED WITH THIS SHORTWAVE AND WILL
CONTINUE THE RISK FOR GUSTY WINDS FROM
THUNDERSTORMS...MAINLY ACROSS EASTERN AND SOUTHERN AREAS. THIS
SHORTWAVE AND ASSOCIATED LLJ WILL DEPART TO THE EAST BY LATE
EVENING. WITH THE NOW EASTWARD THETA-E RIDGE AXIS AND SOMEWHAT DRIER
AIR FOUND BEHIND THE SHORTWAVE THE CWA SHOULD SEE DIMINISHED SHOWER
ACTIVITY OVERNIGHT.

THERE ARE STILL MODEL DIFFERENCES ON TIMING OF SHORTWAVES AND AREAS
OF BUBBLE HIGH PRESSURES BEHIND CONVECTIVE COLD FRONTS. THIS IS LARGELY
DUE TO HOW UPSTREAM AND PRECEDING CONVECTION WILL PAN OUT TO CLOSE
THE WEEKEND. ON MONDAY IT DOES APPEAR THAT A LITTLE BUBBLE OF HIGH
PRESSURE WILL PASS ACROSS THE EASTERN GREAT LAKES REGION FROM THE
OHIO VALLEY. ACCOMPANYING THIS LITTLE AREA OF HIGH PRESSURE WILL BE
DRIER AIR/DRY SLOT SANDWICHED BETWEEN A CONVECTIVE BOUNDARY TO OUR
EAST AND UPPER LEVEL TROUGH TO THE WEST. THIS SLOT OF DRIER AIR WILL
HELP TO LOWER SURFACE DEWPOINTS SOME. DAYTIME SUNSHINE WILL
BE STRONG ENOUGH TO CREATE MODEST LEVELS OF INSTABILITY...AND THOUGH
THERE WILL BE LESS MOISTURE IN THE ATMOSPHERE...A FEW SCATTERED
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ESPECIALLY TOWARDS
CENTRAL NEW YORK. LINGERING CONVECTIVE BOUNDARIES COULD SPARK
CONVECTION WITHIN AN INCREASINGLY CYCLONIC FLOW ALOFT AND WILL
CONTINUE WITH LOW CHANCE POPS ACROSS THE CWA GIVEN THE UNCERTAINTY
OF WHERE CONVECTIVE BOUNDARIES WILL LIE.

MONDAY NIGHT THIS LITTLE BUBBLE OF HIGH PRESSURE WILL SLIP EASTWARD
AND A SOUTHERLY RETURN FLOW WILL ALLOW FOR MOISTURE TO AGAIN CREEP
NORTHEASTWARD INTO SW NYS BY TUESDAY MORNING. A FEW ISOLATED SHOWERS
MAY LINGER MONDAY NIGHT ACROSS THE CWA. OVERNIGHT LOWS MONDAY NIGHT
WILL BE A LITTLE COOLER THAN SUNDAY NIGHT...BOTH IN THE TEMPERATURE
AND DEWPOINT TEMPERATURE DEPARTMENT. LOWS MONDAY NIGHT WILL DROP
BACK INTO THE UPPER 50S TO LOWER 60S WITH LOWER HUMIDITY READINGS.

ON TUESDAY THERE LIKELY WILL STILL BE ONE MORE DAY OF SUMMER-LIKE
WEATHER WITH TEMPERATURES CLIMBING INTO THE LOWER 80S ALONG WITH
SUMMERY HUMIDITY LEVELS. A COLD FRONT WILL SWEEP ACROSS THE CWA
TUESDAY AND SHOWERS AND THUNDERSTORMS WILL BE LIKELY ALONG THIS
FRONTAL BOUNDARY. THOUGH THERMODYNAMICS (LITTLE CAPE/POOR LAPSE
RATES) ARE NOT THAT IMPRESSIVE WITH THIS SYSTEM THERE WILL BE
IMPRESSIVE KINEMATICS (60+ KNOTS OF 0-6 KM BULK SHEAR) AND DYNAMICS
(UPPER LEVEL SHORTWAVE/RIGHT ENTRANCE REGION OF 250 HPA JET) THAT
WILL MAINTAIN THUNDERSTORM POTENTIAL...WHICH COULD TRANSPORT
STRONGER WIND GUSTS DOWN TO THE SURFACE.

TUESDAY EVENING THE COLD FRONT WILL BE EXITING EASTWARD FROM CENTRAL
NEW YORK WITH THE SHOWERS AND THUNDERSTORMS FOLLOWING SUITE. WILL
LEAVE ISOLATED SHOWER POTENTIAL ACROSS THE CWA THE REMAINDER OF THE
NIGHT WITH THE DEEP UPPER LEVEL TROUGH NEARING.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
THIS TIME PERIOD WILL START WITH A HIGHLY AMPLIFIED RIDGE/TROUGH
COMBINATION ACROSS NORTH AMERICA...WITH A RIDGE TO THE WEST AND A
TROUGH TO THE EAST.

ON WEDNESDAY AN UNSEASONABLY COOL AIRMASS WILL INVADE THE EASTERN
GREAT LAKES AS THE CENTER OF THE UPPER LEVEL TROUGH OF LOW PRESSURE
ADVANCES EASTWARD. TEMPERATURES AT 850 HPA WILL DROP TO AROUND +7C
OVER LAKE ONTARIO AND +8C OVER LAKE ERIE. LAKE TEMPERATURES ARE
19-20C ON LAKE ONTARIO AND 22C ON LAKE ERIE. THIS COOL AIRMASS OVER THE
WARM LAKE WATERS WILL LIKELY TRIGGER LAKE EFFECT CLOUDINESS...AND ON
A WESTERLY FLOW POSSIBLY LAKE EFFECT RAIN SHOWERS. WILL PLACE HIGHER
CHANCES FOR RAIN SHOWERS IN THE TYPICAL HIGHER TERRAIN EAST OF BOTH
LAKES WHERE AN ADDITIONAL COMPONENT OF OROGRAPHIC LIFT WILL BRING
HIGH CHANCES FOR RAIN SHOWERS. ELSEWHERE WILL CONTINUE WITH LOW
CHANCE POP FOR SCATTERED DAYTIME INSTABILITY SHOWERS UNDER THE UPPER
LEVEL LOW.

WEDNESDAY NIGHT EXPECT A REDUCTION IN PRECIPITATION ACROSS THE
REGION WITH THE LOSS OF DAYTIME HEATING. ANY CLEARING WILL BRING
COOL OVERNIGHT LOWS IN THE 40S. HOWEVER ANY LINGERING LAKE
CLOUDINESS WILL LIMIT THE RADIATIONAL LOSS OF HEAT AND KEEP
OVERNIGHT LOWS IN THE 50S.

THURSDAY THE UPPER LEVEL LOW WILL ADVANCE NORTHEASTWARD TOWARDS
JAMES BAY...WITH A SHORTWAVE SPOKE OF LOW PRESSURE OVER THE EASTERN
GREAT LAKES REGION. AGAIN WITH SIMILAR 850 HPA TEMPERATURES THERE
WILL BE A SLIGHT CHANCE FOR RAIN SHOWERS...ESPECIALLY EAST OF THE
LAKES WHERE LAKE ENHANCEMENT/OROGRAPHIC LIFT RAIN SHOWERS WILL MORE
LIKELY.

FRIDAY AND SATURDAY WARMER AIR TO THE SOUTH WILL BEGIN TO PUSH
NORTHWARD BEHIND THE DEPARTURE OF THE UPPER LEVEL TROUGH. THIS WILL
END THE LAKE EFFECT RAIN CHANCES...AND WITH LESS DAYTIME
INSTABILITY...AND THE PRESENCE OF SURFACE HIGH PRESSURE A RETURN TO
SUNSHINE AND MORE SUMMER-LIKE AIR TEMPERATURES WILL OCCUR. WITH THIS
SUNSHINE AFTERNOON HIGHS WILL RISE INTO THE MID TO UPPER 70S ACROSS
THE REGION ON FRIDAY...AND UPPER 70S AND LOWER 80S ON SATURDAY.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 06Z...REGIONAL RADAR IMAGERY SHOWS A MODEST BAND OF SHOWERS
LIFTING NORTHEAST ACROSS SOUTHERN ONTARIO IN ASSOCIATION WITH AN
APPROACHING WARM FRONT. ON ITS CURRENT TRAJECTORY...THE SOUTHERNMOST
PORTION OF THIS BAND MAY CLIP PARTS OF THE NIAGARA FRONTIER AND
LOWER GENESEE VALLEY PRIOR TO SUNRISE...THOUGH WILL BE HIGHLY
UNLIKELY TO PRODUCE ANY RESTRICTIONS. BEHIND THIS...CONDITIONS
REMAIN DRY AND VFR ALL THE WAY UPSTREAM TO CENTRAL LOWER
MICHIGAN...WHERE A LARGER BAND OF SHOWERS AND EMBEDDED THUNDERSTORMS
CONTINUES TO PRESS EASTWARD. WHILE THIS SECOND AREA SHOULD WEAKEN
SOME OVERNIGHT AS IT PRESSES INTO PROGRESSIVELY MORE STABLE AIR...IT
SHOULD STILL HOLD TOGETHER ENOUGH TO REACH FAR WESTERN NEW YORK IN
THE 10Z-12Z TIME FRAME JUDGING FROM CURRENT RADAR TRENDS...BEFORE
BODILY PUSHING EAST ACROSS THE AREA DURING THE MORNING ALONG WITH
SOME ATTENDANT MVFR/LOCALIZED IFR CONDITIONS.

BY SUNDAY AFTERNOON AT LEAST MODEST SURFACE HEATING WILL TAKE PLACE
BEHIND THE FIRST BATCH OF SHOWERS AND PRODUCE ENOUGH INSTABILITY FOR
ADDITIONAL CONVECTION. BY THIS TIME A HEALTHY SOUTHWEST FLOW WILL
HAVE DEVELOPED...SO EXPECT LAKE SHADOWS NORTHEAST OF LAKE ERIE AND
EVENTUALLY LAKE ONTARIO. ADDITIONAL CONVECTION WILL BE MOST
PREVALENT FROM THE INTERIOR SOUTHERN TIER INTO THE FINGER LAKES AND
CENTRAL NY...WITH SOME POTENTIAL AS WELL ALONG THE NIAGARA PENINSULA
BETWEEN LAKE ERIE AND ONTARIO. A FEW OF THESE AFTERNOON STORMS MAY
BECOME STRONG WIND GUSTY WINDS.

THE SOUTHWEST WINDS WILL BECOME QUITE GUSTY FROM LATE MORNING
THROUGH AFTERNOON ACROSS WESTERN NY...WITH GUSTS POTENTIALLY IN THE
30 KNOT RANGE OVER AND NORTHEAST OF LAKE ERIE INCLUDING KBUF-KIAG.

SUNDAY NIGHT...EXPECT MVFR/LOCALIZED IFR WITH SHOWERS AND
THUNDERSTORMS LIKELY IN THE EVENING ACROSS EASTERN SECTIONS...THEN
IMPROVING TO VFR WITH A CHANCE OF SHOWERS OVERNIGHT SOUTH AND EAST.

OUTLOOK...
MONDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS.
TUESDAY...VFR TO MVFR IN SCATTERED SHOWERS AND THUNDERSTORMS.
WEDNESDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.
THURSDAY...VFR WITH A SLIGHT CHANCE OF SHOWERS.

&&

.MARINE...
HIGH PRESSURE AND CALM CONDITIONS ON THE LAKES TONIGHT WILL GIVE WAY
TO MORE UNSETTLED WEATHER LATE TONIGHT AS A WARM FRONT CROSSES THE
LAKES...BRINGING SHOWERS AND THUNDERSTORMS TO THE LAKES. THE RISK OF
SHOWERS AND THUNDERSTORMS...SOME POSSIBLY SEVERE...WILL CONTINUE
THROUGH SUNDAY. IN ADDITION...A SOUTHWESTERLY PUSH DOWN LAKE ERIE
BEHIND A WEAKENING COLD FRONT IS EXPECTED TO BRING A BRIEF BUT STOUT
ROUND OF SMALL CRAFT WINDS AND WAVES FROM LATE MORNING THROUGH
EVENING ON SUNDAY. SOME OF THESE STRONGER WINDS WILL ALSO CROSS THE
NIAGARA RIVER AND WEST END OF LAKE ONTARIO AS WELL...WHERE SMALL
CRAFT ADVISORIES HAVE ALSO BEEN POSTED. UNSETTLED WEATHER WILL
PERSIST INTO TUESDAY...THOUGH WINDS AND WAVES SHOULD DROP BACK BELOW
SCA LEVELS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM NOON TODAY TO 11 PM EDT THIS EVENING
         FOR LEZ020-040-041.
         SMALL CRAFT ADVISORY FROM NOON TODAY TO 11 PM EDT
         THIS EVENING FOR LOZ030-042.

&&

$$

SYNOPSIS...JJR/WOOD
NEAR TERM...HITCHCOCK/JJR/WOOD
SHORT TERM...THOMAS
LONG TERM...THOMAS
AVIATION...HITCHCOCK/JJR
MARINE...HITCHCOCK/WOOD







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