Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 122359
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
759 PM EDT SAT JUL 12 2014

.SYNOPSIS...
HIGH PRESSURE AND FAIR WEATHER THIS EVENING WILL GIVE WAY TO HUMID
AND STORMY WEATHER 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 SUNDAY/...
HIGH PRESSURE WILL CONTINUE TO DRIFT OFF THE NEW ENGLAND COAST
TONIGHT AND BEGIN TO GIVE WAY TO THE NEXT UPSTREAM SYSTEM. DENSE
CIRRUS IS ALREADY OVERSPREADING WESTERN NY...AND WILL CONTINUE TO
THICKEN AND LOWER OVERNIGHT FROM WEST TO EAST.

BY LATE TONIGHT/EARLY SUNDAY MORNING HIGHER THETA-E AIR IS EXPECTED
TO ARRIVE OVER THE REGION ON THE NOSE OF A 35-45KT LOW LEVEL JET
THAT EXTENDS DOWN TO 925MB. THIS IS EXPECTED TO FORCE AN AREA OF
ELEVATED CONVECTION REACHING THE NIAGARA FRONTIER FIRST JUST BEFORE
DAYBREAK. THIS WILL QUICKLY OVERSPREAD THE REST OF THE AREA DURING
THE EARLY TO MID MORNING. EXPECT SHOWERS AND SCATTERED THUNDER TO
LAST FOR 3-5 HOURS AT ANY GIVEN LOCATION...WITH THIS FIRST BATCH
TAPERING OFF ACROSS WESTERN NY BY LATE MORNING OR MIDDAY THEN DURING
THE AFTERNOON EAST OF LAKE ONTARIO. WHILE THIS INITIAL ROUND OF
CONVECTION 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 /SUNDAY NIGHT 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 /00Z SUNDAY THROUGH THURSDAY/...
VFR WILL PREVAIL FOR THE FIRST 9 HOURS OR SO OF THE 00Z TAF CYCLE.
DENSE CIRRUS LEVEL CLOUDS WILL OVERSPREAD THE REGION FROM WEST TO
EAST TONIGHT AND GRADUALLY LOWER INTO A MID LEVEL DECK. A WARM FRONT
AND MID LEVEL DISTURBANCE WILL REACH WESTERN NY AROUND 09Z WITH
INCREASING CHANCES OF SHOWERS AND SCATTERED THUNDERSTORMS. THIS
FIRST ROUND OF SHOWERS AND STORMS WILL TRANSLATE FROM WEST TO EAST
ACROSS THE REGION DURING THE 09Z-16Z TIME FRAME WITH SHOWERS LASTING
AT ANY ONE SPOT FOR 3-5 HOURS. THIS WILL PRODUCE AREAS OF MVFR WITH
LOCAL IFR IN ANY HEAVIER THUNDERSTORMS. UPSTREAM TRENDS AND MODEL
GUIDANCE WOULD SUGGEST THE POTENTIAL FOR A PERIOD OF MVFR CIGS
LINGERING FOR A FEW HOURS BEHIND THE MORE PERSISTENT SHOWERS...WITH
IFR NOT OUT OF THE QUESTION ACROSS THE HIGHER TERRAIN.

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
30-35 KNOT RANGE OVER AND NORTHEAST OF LAKE ERIE INCLUDING KBUF-KIAG.

OUTLOOK...
SUNDAY NIGHT...MVFR/LOCALIZED IFR WITH SHOWERS AND THUNDERSTORMS
LIKELY IN THE EVENING EASTERN SECTIONS...THEN IMPROVING TO VFR WITH
A CHANCE OF SHOWERS OVERNIGHT SOUTH AND EAST.
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 TO 11 PM EDT SUNDAY FOR LEZ020-
         040-041.
         SMALL CRAFT ADVISORY FROM NOON TO 11 PM EDT SUNDAY
         FOR LOZ030-042.

&&

$$

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





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