Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 280913
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
513 AM EDT THU AUG 28 2014

.SYNOPSIS...
COOLER AIR WILL CONTINUE TO POUR IN ACROSS THE REGION TODAY...WITH A
RETURN TO BELOW NORMAL TEMPERATURES BEFORE TEMPERATURES RETURN TO
NEAR NORMAL FRIDAY. THE NEXT OPPORTUNITY FOR PRECIPITATION WILL ARRIVE
FOR THE LABOR DAY WEEKEND...WHEN A COMPLEX FRONTAL SYSTEM WILL
SLOWLY MOVE ACROSS THE REGION.

&&

.NEAR TERM /THROUGH TONIGHT/...
HEART OF REAL COLD AIR ADVECTION JUST NOW GETTING UNDERWAY ACROSS
LAKE ONTARIO AT 09Z...AND SHOULD BE IN FULL FORCE ACROSS EASTERN
LAKE ERIE BY 12Z OR SO...THUS EXPECT LAKE EFFECT CLOUD COVERAGE TO
BE ON THE INCREASE THROUGH THIS MORNING UNDER INCREASINGLY COOLER
NORTHWEST FLOW. 850MB TEMPS WILL AVERAGE +7C OVER THE AREA TODAY
WHICH IS COOL ENOUGH TO ELICIT A LAKE EFFECT RESPONSE WITH
CLOUDINESS DEVELOPING TO THE SOUTH AND SOUTHEAST OF THE LAKES. LOW
CLOUD DECKS SHOULD BE THIN HOWEVER AS ASIDE FROM LAKE INFLUENCE AIR
ALOFT IS VERY DRY. EXPECT DECKS TO BREAK UP LATER THIS AFTERNOON AS
STRONG AUGUST SUN COUNTERACTS LAKE INFLUENCE AND DRIER AIR MOVING IN
ALOFT WILL ALSO MIX DOWN THANKS TO DIURNAL HEATING. THAT
SAID...WOULD EXPECT SOME DIURNAL CUMULUS EARLY THIS AFTERNOON DUE TO
THE COOL POOL OVERHEAD BEFORE BETTER MIXING OCCURS. ALSO AIDING IN
CLOUD COVER DIMINISHING LATER TODAY WILL BE STRONGER SUBSIDENCE
MOVING INTO THE AREA ASSOCIATED WITH AN AREA OF HIGH PRESSURE MOVING
FROM THE UPPER GREAT LAKES INTO THE LOWER LAKES BY LATE IN THE DAY.
BREAKS OF SUN WILL NOT BE ENOUGH TO OFFSET THE COOL AIR ADVECTION
THROUGHOUT THE DAY...WITH HIGHS IN THE UPPER 60S TO AROUND 70.

THIS AREA OF HIGH PRESSURE WILL CREST OVER THE REGION TONIGHT
PROVIDING LIGHT WINDS...AND CLEAR TO PARTLY CLOUDY SKIES ACROSS THE
REGION. LATE TONIGHT CLEAR SKIES AND LIGHT WINDS WILL MEAN EXCELLENT
CONDITIONS FOR TYPICAL VALLEY FOG TO FORM ACROSS PORTIONS OF THE
WESTERN SOUTHERN TIER. EXPECT A VERY COOL SUMMER NIGHT ACROSS THE
AREA WITH LOWS GETTING DOWN INTO THE MID TO UPPER 40S ACROSS THE
HIGHER TERRAIN OF THE WESTERN SOUTHERN TIER AND EASTERN LAKE ONTARIO
REGION. EXPECT LOWS MAINLY IN THE LOWER 50S OVER LOWLAND
AREAS...WITH MID 50S BEING FOUND RIGHT ALONG THE LAKE SHORES.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
FRIDAY HIGH PRESSURE WILL BUILD FROM THE LOWER LAKES IN THE MORNING
TO OFF THE NEW ENGLAND COAST BY EVENING AS A MID LEVEL RIDGE BUILDS
OVERHEAD. WARM ADVECTION WILL INCREASE AROUND THE WESTERN PERIPHERY
OF THE DEPARTING HIGH...ALLOWING TEMPERATURES TO RECOVER SOME AFTER
A COOL THURSDAY. EXPECT HIGHS IN THE MID TO UPPER 70S ACROSS WESTERN
NY...WITH LOWER 70S ON THE HILLS AND EAST OF LAKE ONTARIO. CLEAR
SKIES IN THE MORNING WILL GIVE WAY TO SOME INCREASE IN MID/HIGH
CLOUD COVER DURING THE DAY IN RESPONSE TO WARM ADVECTION...MAINLY
FROM THE GENESEE VALLEY WESTWARD.

A POORLY DEFINED WARM FRONT WILL LIFT NORTHEAST ACROSS THE REGION
FRIDAY NIGHT AND BRING A PERIOD OF ISENTROPIC UPGLIDE AND ENHANCED
CONVERGENCE AND MOISTURE. A WEAK MID LEVEL VORTICITY MAXIMA WILL
ALSO TRAVERSE THE NORTHERN EDGE OF THE RIDGE...PROVIDING SOME WEAK
LARGE SCALE ASCENT. THE COMBINATION OF WARM ADVECTIVE FORCING AND
MOISTURE MAY BE ENOUGH TO PRODUCE A FEW SPRINKLES FRIDAY NIGHT IN
SOME AREAS ALONG WITH INCREASED CLOUD COVER. THE BEST CHANCE FOR ANY
MEASURABLE SHOWERS WILL BE OVER AND EAST OF LAKE ONTARIO OVERNIGHT
INTO SATURDAY MORNING WHERE LATEST MODEL GUIDANCE SHOWS ASCENT AND
MOISTURE MAXIMIZED. THE INCREASE IN CLOUD COVER AND RETURN FLOW WILL
KEEP TEMPERATURES MILDER...WITH LOWS IN THE LOWER 60S ON THE LAKE
PLAINS OF WESTERN NY AND MID TO UPPER 50S IN THE COOLER INTERIOR
SOUTHERN TIER AND EAST OF LAKE ONTARIO.

ON SATURDAY THE RETREATING WARM FRONT MAY PRODUCE A FEW SHOWERS IN
THE MORNING ACROSS THE NORTH COUNTRY WITH ONGOING WARM ADVECTION AND
ENHANCED MOISTURE CONVERGENCE. ELSEWHERE THE MORNING SHOULD BE
MAINLY DRY AS THE WARM SECTOR BECOMES ESTABLISHED. BY AFTERNOON THE
COMBINATION OF DIURNAL SURFACE HEATING AND INCREASING BOUNDARY LAYER
MOISTURE WILL CONTRIBUTE TO MODERATE INSTABILITY...WITH SBCAPE IN
MODEL GUIDANCE REACHING THE 1500-2000J/KG RANGE. MID LEVEL
TEMPERATURES WILL BE ON THE WARM SIDE WHICH MAY HOLD ONTO SOME CINH
INITIALLY...BUT CONVERGENCE ALONG LAKE BREEZE AND TERRAIN BOUNDARIES
SHOULD BE SUFFICIENT TO FORCE WIDELY SCATTERED DEEP MOIST CONVECTION
DURING THE AFTERNOON...WITH THE GREATEST CHANCES ACROSS THE SOUTHERN
TIER AND FINGER LAKES. SOUTHWEST FLOW OFF BOTH LAKES SHOULD ALLOW
STABLE LAKE SHADOWS TO DEVELOP...WITH A MUCH LESSER CHANCE OF ANY
SHOWERS OR STORMS NEAR KBUF AND KART. 850MB TEMPS NEAR 17C WILL
SUPPORT HIGHS IN THE MID TO UPPER 80S AT LOWER ELEVATIONS ACROSS
WESTERN NY...WITH LOWER 80S ACROSS THE SOUTHERN TIER HILLS AND EAST
OF LAKE ONTARIO.

THE BEST CHANCE OF SOMEWHAT MORE WIDESPREAD SHOWERS AND STORMS NOW
APPEARS TO BE SATURDAY NIGHT INTO EARLY SUNDAY MORNING WHEN A LOW
AMPLITUDE MID LEVEL SHORTWAVE WILL CROSS THE LOWER LAKES...WITH AN
ATTENDANT BELT OF 30+ KNOT 900-700MB FLOW ENHANCING CONVERGENCE
ALONG A PRE-FRONTAL TROUGH. THERE WILL BE AMPLE MOISTURE TO WORK
WITH AS PWAT RISES TO NEAR 2 INCHES. GIVEN THE COMBINATION OF
FORCING... MOISTURE...AND LINGERING INSTABILITY WILL GO WITH LIKELY
POPS FOR LATER SATURDAY NIGHT ACROSS THE ENTIRE REGION...WITH LIKELY
POPS LASTING INTO SUNDAY MORNING ACROSS THE EASTERN HALF OF THE
AREA. MODEL GUIDANCE HAS BEEN SHOWING A GOOD DEAL OF VARIANCE WITH
RESPECT TO THE TIMING OF THIS FEATURE AND THUS THE BEST CHANCES OF
RAIN OVER THE WEEKEND...BUT MOST GUIDANCE APPEARS TO NOW BE FOCUSING
ON THIS PERIOD.

BY SUNDAY AFTERNOON DOWNWARD VERTICAL MOTION BEHIND THE WEAK MID
LEVEL TROUGH SHOULD ALLOW SHOWERS AND STORMS TO BECOME MORE WIDELY
SCATTERED IN NATURE...ALTHOUGH DIURNAL INSTABILITY WILL PROBABLY
KEEP AT LEAST A FEW GOING. STABLE LAKE SHADOWS MAY DEVELOP DURING
THE AFTERNOON WITH THE KBUF AND KART AREAS SEEING THE LOWEST CHANCE
OF RAIN ONCE AGAIN AND EVEN SOME SUNSHINE. 850MB TEMPS GET KNOCKED
BACK A LITTLE FOLLOWING THE TROUGH PASSAGE...SO EXPECT HIGHS IN THE
LOWER TO MID 80S IN MOST AREAS.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
SUNDAY NIGHT A MID LEVEL TROUGH WILL EXIT ACROSS SOUTHERN QUEBEC
WITH A FLAT MID LEVEL RIDGE BUILDING TEMPORARILY ACROSS THE LOWER
LAKES. THIS SHOULD BRING AT LEAST A REDUCTION IN THE COVERAGE OF
CONVECTION ACROSS THE REGION...ALTHOUGH A FEW SHOWERS OR AN ISOLATED
THUNDERSTORM MAY LINGER. GIVEN THE UNCERTAINTY IN TIMING OF
INDIVIDUAL SHORTWAVE FEATURES AT THIS LEAD TIME WILL KEEP LOW CHANCE
POPS FOR SUNDAY NIGHT. ON LABOR DAY MONDAY ANOTHER WEAK SURFACE AND
MID LEVEL TROUGH WILL MOVE INTO THE GREAT LAKES REGION AND SUPPORT A
FEW MORE SHOWERS AND THUNDERSTORMS...WITH THE BEST CHANCES LATER IN
THE DAY AND INTO MONDAY NIGHT. DESPITE THE RAIN CHANCES THERE SHOULD
BE LENGTHY RAIN FREE PERIODS AS WELL. THIS TROUGH WILL EXIT ON
TUESDAY WITH A LOW CHANCE OF A LINGERING SHOWER OR STORM.

THE 00Z GFS AND ECMWF BOTH BUILD SURFACE HIGH PRESSURE INTO THE
LOWER LAKES BY TUESDAY NIGHT AND WEDNESDAY WITH A RETURN TO DRY
WEATHER.

TEMPERATURES THROUGH THE LONG TERM PERIOD WILL START A LITTLE ABOVE
AVERAGE ON MONDAY WITH HIGHS IN THE LOW TO MID 80S BEFORE PULLING
BACK INTO THE 70S BY MIDWEEK AS A BUBBLE OF COOLER AND DRIER AIR
BUILDS INTO THE GREAT LAKES REGION.

&&

.AVIATION /09Z THURSDAY THROUGH MONDAY/...
AS OF 09Z...LAKE EFFECT CLOUDS PRODUCING MAINLY JUST SOME LOW
VFR/MVFR SCATTERED DECKS ABOUT THE AREA. AIR IS JUST TO DRY ACROSS
WESTERN NEW YORK TO PRODUCE ANY CEILINGS UNTIL BETTER LAKE INFLUENCE
IS REALIZED. THAT SAID...A BIT MORE MOISTURE AND COOL NORTHWEST FLOW
WILL KEEP THE 4-6KT DECK IN PLACE ACROSS THE KART TERMINAL THROUGH
THIS MORNING.

HEART OF REAL COLD AIR ADVECTION JUST NOW GETTING UNDERWAY ACROSS
LAKE ONTARIO...AND SHOULD BE IN FULL FORCE ACROSS EASTERN LAKE ERIE
BY 12Z OR SO...THUS EXPECT LAKE EFFECT CLOUD COVERAGE TO BE ON THE
INCREASE THROUGH THIS MORNING UNDER INCREASINGLY COOLER NORTHWEST
FLOW ALOFT. EXPECTING MAINLY MVFR CIGS ACROSS WNY TERMINALS THROUGH
THE MORNING. MVFR CIGS SHOULD BE THIN HOWEVER AS ASIDE FROM LAKE
INFLUENCE THE AIR IS VERY DRY. CONDITIONS SHOULD IMPROVE BACK TO VFR
FOR MOST LOCATIONS BY EARLY AFTERNOON AS STRONG AUGUST SUN
COUNTERACTS LAKE INFLUENCE AND DRIER AIR WILL BE ALLOWED TO MIX DOWN
FROM ALOFT THANKS TO DIURNAL HEATING. WOULD STILL EXPECT SOME
DIURNAL CUMULUS EARLY IN THE AFTERNOON...WITH ANY VFR CIGS
SCATTERING OUT BY LATE IN THE DAY AS EVEN DRIER AIR AND STRONGER
SUBSIDENCE MOVES INTO THE AREA.

PARTLY CLOUDY TO CLEAR SKIES CAN BE EXPECTED LATE THIS EVENING
THROUGH EARLY TONIGHT PROVIDING VFR CONDITIONS AT ALL TERMINALS
THROUGH 06Z.

OUTLOOK...
FRIDAY THROUGH FRIDAY NIGHT...VFR.
SATURDAY THROUGH SUNDAY...MAINLY VFR WITH CHANCE OF
SHOWERS/THUNDERSTORMS.
MONDAY...VFR/MVFR IN SCATTERED SHOWERS AND THUNDERSTORMS.

&&

.MARINE...
NORTHWEST FLOW WILL AVERAGE AROUND 15 KNOTS THROUGH EARLY MORNING.
WAVES HAVE TOPPED OUT AT AROUND 3 FEET...WITH CONDITIONS JUST SHY OF
SMALL CRAFT CRITERIA...BUT THERE STILL IS A DECENT CHOP ON THE
WATERS. WAVES PUSHING UP NEAR 4 FEET EARLY THIS MORNING ACROSS
SOUTHEASTERN LAKE ONTARIO WILL SUBSIDE AS WINDS SHIFT TO THE NORTH
AND LESSEN THROUGH THE MORNING. WAVES 2 FEET OR LESS ON LAKE ERIE
WILL ALSO SUBSIDE AS WINDS DIMINISH SOME AS THE PRESSURE GRADIENT
RELAXES TODAY.

&&

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

&&

$$

SYNOPSIS...JM
NEAR TERM...JM
SHORT TERM...HITCHCOCK
LONG TERM...HITCHCOCK
AVIATION...JM
MARINE...JM







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