Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 041442
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1042 AM EDT WED MAY 4 2016

.SYNOPSIS...
A DEEP UPPER LEVEL TROUGH CENTERED OVER THE UPPER GREAT LAKES WILL
GRADUALLY SETTLE ACROSS THE REGION THROUGH THE END OF THE WORK WEEK.
AS A RESULT...WE CAN EXPECT SOMEWHAT UNSETTLED WEATHER OVER THE NEXT
FEW DAYS...THOUGH TEMPERATURES WILL REMAIN FAIRLY CLOSE TO NORMAL
LEVELS FOR EARLY MAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
DURING THE COURSE OF THIS PERIOD...THE CORE OF A DEEP UPPER LEVEL
TROUGH CURRENTLY CENTERED OVER THE UPPER GREAT LAKES AND ONTARIO
PROVINCE WILL SETTLE SOUTHWARD INTO THE OHIO VALLEY. AS THIS OCCURS...
A PAIR OF SURFACE LOWS OVER THE UPPER GREAT LAKES AND VIRGINIA
COAST WILL GRADUALLY CONSOLIDATE INTO A SINGLE BROAD LOW JUST OFF
THE MID ATLANTIC COASTLINE. DURING THIS CONSOLIDATION PHASE... A
WEAK INVERTED SURFACE TROUGH WILL DEVELOP FROM THE SOUTHERN TIER
TO THE NORTH COUNTRY TODAY...BEFORE SHIFTING WESTWARD AND
GRADUALLY DISSIPATING TONIGHT.

AS WE PROGRESS THROUGH THE DAY TODAY...MAINLY DRY WEATHER TO
START OFF THE DAY WILL GRADUALLY GIVE WAY TO MORE UNSETTLED
CONDITIONS THROUGH THE LATE MORNING AND EARLY AFTERNOON HOURS AS
THE COMBINATION OF DIURNAL HEATING AND THE APPROACHING UPPER LEVEL
TROUGH/COOLING AIRMASS ALOFT LEADS TO DESTABILIZATION OF THE
ATMOSPHERE ACROSS OUR REGION. COUPLED WITH SOME WEAK TO MODEST
MOISTURE ADVECTION ALONG AND TO THE EAST OF THE DEVELOPING
INVERTED TROUGH AND INCREASING LOW LEVEL CONVERGENCE ALONG THIS
BOUNDARY...THE ABOVE WILL LEAD TO THE DEVELOPMENT OF SOME
DIURNALLY-DRIVEN SHOWER ACTIVITY...ALONG WITH SOME LIMITED
POTENTIAL FOR A FEW EMBEDDED THUNDERSTORMS GIVEN STEEPENING LAPSE
RATES. THE GREATEST POTENTIAL FOR ALL OF THIS WILL BE FOUND ALONG
AND EAST OF THE SURFACE TROUGH WHERE THE BEST COMBINATION OF
MOISTURE/LIFT/INSTABILITY WILL BE IN PLAY...AND WHERE LIKELY POPS
HAVE BEEN RETAINED FROM CONTINUITY. NORTH AND WEST OF THE
TROUGH... CONVECTIVE POTENTIAL WILL LOWER MARKEDLY WITH INCREASING
NORTHWESTWARD EXTENT...WITH LITTLE IF ANY CHANCE FOR RAIN FOUND
ALONG THE SOUTH SHORES OF LAKES ERIE AND ONTARIO WHERE A
STABILIZING NORTHERLY/ NORTHEASTERLY LOW LEVEL FLOW WILL COME INTO
PLAY. TEMPERATURE-WISE... 850 MB TEMPS WILL RANGE BETWEEN +2C TO
+6C TODAY...AND THIS SHOULD BE SUPPORTIVE OF HIGHS MAINLY IN THE
LOWER HALF OF THE 60S GIVEN THE EXPECTED AMOUNT OF CLOUD COVER AND
SHOWER ACTIVITY. THE MAIN EXCEPTION TO THIS WILL BE RIGHT ALONG
AND A BIT INLAND FROM THE SOUTH SHORES OF THE LAKES...WHERE THE
AFOREMENTIONED NORTHERLY/NORTHEASTERLY FLOW OFF THE MUCH COOLER
LAKE WATERS WILL KEEP HIGHS CONFINED TO THE UPPER 40S AND 50S.

TONIGHT...THE DIURNALLY-DRIVEN SHOWERS SHOULD TEND TO QUICKLY
FADE AND DECREASE IN AREAL COVERAGE WITH THE LOSS OF DAYTIME
HEATING THIS EVENING...THOUGH SOME WIDELY SCATTERED TO SCATTERED
ACTIVITY MAY STILL MANAGE TO HANG ON THROUGH THE NIGHT ALONG THE
INVERTED TOUGH AS IT SHIFTS WESTWARD AND WEAKENS. OTHERWISE EXPECT
A FAIR AMOUNT OF CLOUD COVER TO REMAIN IN PLACE ACROSS THE
REGION...WITH OVERNIGHT LOWS AVERAGING OUT IN THE MID 40S.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
ON THURSDAY A MID LEVEL CLOSED LOW WILL MOVE FROM THE SOUTHERN
APPALACHIANS TO THE CAROLINA COAST WITH A WEAK INVERTED TROUGH
EXTENDING NORTHWARD TO LAKE ONTARIO. THE MAJORITY OF THE ORGANIZED
FORCING FOR ASCENT WILL FOLLOW THE CLOSED LOW INTO THE CAROLINAS...
WITH VERY WEAK PERIODS OF DPVA AND CONVERGENCE ACROSS WESTERN AND
CENTRAL NY. GIVEN THE WEAK FORCING...EXPECT ANY SHOWERS TO BE
PARTIALLY TIED TO THE DIURNAL CYCLE WITH THE GREATER CHANCES DURING
THE AFTERNOON AND EVENING ACROSS THE HIGHER TERRAIN WELL INLAND FROM
THE LAKES. COVERAGE WILL BE LOWEST ON THE LAKE PLAINS WITH SOME
STABILIZING INFLUENCE FROM THE LAKES...WITH EXTENDED RAIN FREE TIME
IN MANY AREAS. CLOUDS WILL LIMIT TEMPERATURES WITH HIGHS IN THE
LOWER 60S IN MOST AREAS THURSDAY...WITH SOME MID 60S ACROSS THE
NORTH COUNTRY WHERE SOME BREAKS IN THE CLOUDS ARE MORE LIKELY.

THE INVERTED TROUGH REMAINS IN PLACE THURSDAY NIGHT WITH DEEPER
MOISTURE RETREATING INTO CENTRAL NY AND PA. WITH THE SOMEWHAT DRIER
AIRMASS AND DIURNAL STABILIZATION OF THE BOUNDARY LAYER EXPECT MOST
OF THE SHOWERS TO DIMINISH AND END OVERNIGHT. CLOUD COVER WILL KEEP
LOWS IN THE MID 40S IN MOST AREAS WITH A FEW POCKETS OF LOWER 40S
ACROSS THE INTERIOR SOUTHERN TIER AND LEWIS COUNTY.

ON FRIDAY THE MID LEVEL CLOSED LOW WILL STRENGTHEN OVER THE MID
ATLANTIC...WITH SOME IMPORTANT DIFFERENCES SHOWING UP BY THIS TIME
IN MODEL GUIDANCE. THE 00Z GFS AND ECMWF RUNS HAVE TRENDED A LITTLE
FARTHER NORTH AND WEST WITH THE CLOSED LOW POSITION...AND SPREAD
MORE WIDESPREAD SHOWERS INTO PORTIONS OF THE SOUTHERN TIER AND
CENTRAL NY ON FRIDAY THAN PREVIOUS RUNS. GIVEN THE CONTINUED MODEL
UNCERTAINTY WITH THIS SYSTEM...HAVE OPTED TO MAINTAIN CHANCE POPS
FROM THE SOUTHERN TIER INTO THE GENESEE VALLEY AND CENTRAL NY ON
FRIDAY...WITH A MAINLY DRY FORECAST CLOSE TO THE CANADIAN BORDER.
TEMPERATURES WILL CONTINUE TO SLOWLY MODERATE WITH HIGHS IN THE MID
60S IN MOST AREAS.

FRIDAY NIGHT THE MID LEVEL LOW IS NOW FORECAST TO WEAKEN WITH ANY
SHOWERS IN SOUTHERN AND EASTERN PORTIONS OF THE AREA SLOWLY TAPERING
OFF OVERNIGHT. LOW TEMPERATURES WILL ADD ON A FEW MORE DEGREES OVER
THE PREVIOUS NIGHT...WITH LOWS IN THE UPPER 40S ON THE LAKE PLAINS
AND MID 40S IN COOLER INTERIOR LOCATIONS.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
ON SATURDAY A NARROW RIDGE OF HIGH PRESSURE WILL BUILD INTO THE
LOWER LAKES BETWEEN THE WEAKENING MID ATLANTIC CLOSED LOW AND A COLD
FRONT MOVING INTO THE CENTRAL AND WESTERN LAKES...PROVIDING A MAINLY
DRY DAY. 850MB TEMPS CONTINUE TO RISE TO AROUND +8C BY LATE IN THE
DAY...SUPPORTING HIGHS POSSIBLY INTO THE LOWER 70S IF ENOUGH
SUNSHINE IS REALIZED.

SATURDAY NIGHT A POTENT MID LEVEL TROUGH AND ASSOCIATED SURFACE COLD
FRONT WILL CROSS THE REGION. DYNAMICS CONTINUE TO APPEAR STRONG
ENOUGH WITH THIS SYSTEM TO JUSTIFY HIGH LIKELY POPS...AND SOME
LIMITED INSTABILITY JUST AHEAD OF THE COLD FRONT MAY PRODUCE A FEW
WIDELY SCATTERED THUNDERSTORMS AS WELL.

STRONG COLD ADVECTION BY MAY STANDARDS WILL DEVELOP BEHIND THE COLD
FRONT ON SUNDAY. THIS WILL BRING TEMPERATURES BACK TO BELOW AVERAGE
WITH HIGHS ONLY IN THE MID TO UPPER 50S IN MANY AREAS. THE PASSAGE
OF THE MID LEVEL TROUGH AND ASSOCIATED COLD MID LEVEL TEMPERATURES
MAY SUPPORT A FEW SCATTERED RAIN SHOWERS.

HIGH PRESSURE WILL THEN BRING A RETURN TO DRY WEATHER SUNDAY NIGHT
AND MONDAY. BY TUESDAY MODEL GUIDANCE BEGINS TO DIVERGE...WITH THE
NEW 00Z ECMWF DEVELOPING A WET WARM FRONT ACROSS THE LOWER LAKES
MONDAY NIGHT AND TUESDAY WHILE THE GFS AND CANADIAN GEM MAINTAIN
HIGH PRESSURE. THE ECMWF SOLUTION IS A BREAK FROM THE CONTINUITY OF
PREVIOUS RUNS...SO FOR NOW HAVE OPTED TO MAINTAIN A DRY FORECAST
INTO TUESDAY WITH TEMPERATURES MODERATING BACK TO NEAR AVERAGE.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
THE POTENTIAL FOR SHOWERS WILL INCREASE DURING THE LATE MORNING AND
AFTERNOON HOURS. EXPECT MOSTLY VFR CONDITIONS AND FAIRLY SPARSE
AREAL COVERAGE OF SHOWERS AT THE TAF SITES...WITH MORE NUMEROUS
SHOWERS FOUND ACROSS INTERIOR SECTIONS. WHILE A FEW THUNDERSTORMS
WILL ALSO BE POSSIBLE /PARTICULARLY ACROSS INTERIOR
SECTIONS/...THEIR EXPECTED AREAL COVERAGE REMAINS TOO LOW FOR
INCLUSION IN THE TAFS AT THIS TIME.

TONIGHT...ANY LEFTOVER SHOWERS SHOULD TEND TO DIMINISH IN AREAL
COVERAGE. OTHERWISE GENERAL VFR CONDITIONS SHOULD PERSIST THROUGH
THE EVENING... WITH SOME MVFR/IFR CIGS THEN BECOMING POSSIBLE
OVERNIGHT ACROSS THE HIGHER TERRAIN OF THE SOUTHERN TIER AND FINGER
LAKES.

OUTLOOK...
THURSDAY AND FRIDAY...MAINLY VFR...WITH MVFR POSSIBLE IN SCATTERED
SHOWERS.
SATURDAY...VFR DURING THE DAY...THEN MVFR WITH SHOWERS LIKELY ALONG
WITH A CHANCE OF THUNDERSTORMS SATURDAY NIGHT.
SUNDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.

&&

.MARINE...
THE REMAINDER OF THE WEEK WILL FEATURE A RELATIVELY WEAK PRESSURE
GRADIENT ACROSS THE LOWER LAKES REGION. THIS WILL RESULT IN LIGHT
TO MODEST WINDS PREDOMINATING...ALONG WITH CORRESPONDINGLY MINIMAL
WAVES.

&&

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

&&

$$

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



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