Area Forecast Discussion
Issued by NWS Buffalo, NY

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227
FXUS61 KBUF 011420
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1020 AM EDT SUN MAY 1 2016

.SYNOPSIS...
A WARM FRONT WILL LIFT ACROSS THE REGION TODAY. RAIN WILL TAPER TO
SCATTERED SHOWERS WITH A CHANCE OF THUNDERSTORMS THIS AFTERNOON AND
EVENING WITH ANOTHER ROUND OF MORE WIDESPREAD RAIN TONIGHT AS AN
AREA OF LOW PRESSURE MOVES ACROSS THE LOWER GREAT LAKES. RAIN SHOULD
DIMINISH MONDAY AS THE LOW MOVES AWAY FROM THE REGION. COOL AND
UNSETTLED WEATHER IS EXPECTED TO PREVAIL FOR MUCH OF THE COMING WEEK
AS A DEEP UPPER LEVEL TROUGH SETTLES OVER THE REGION.

&&

.NEAR TERM /THROUGH TONIGHT/...
RADARS ARE SHOWING WIDESPREAD RAIN CONTINUES TO SHIFT NORTHEAST
ACROSS THE FORECAST AREA THIS MORNING. THE RAIN IS OCCURRING AS
MOISTURE IS TRANSPORTED NORTH OVER AND AHEAD OF A SURFACE WARM FRONT
SHIFTING ACROSS THE OHIO VALLEY. THE BACK EDGE OF THIS FIRST ROUND
OF RAIN IS NOW CLEARING THE FAR WESTERN SOUTHERN TIER AT 11Z WHICH
SHOULD CONTINUE EAST TO THE EASTERN LAKE ONTARIO REGION NEAR
LUNCHTIME. TOTAL RAINFALL LOOKING LIKE A QUARTER TO HALF INCH.
TEMPERATURES THIS MORNING ARE RUNNING IN THE 40S FOR MOST LOCATIONS
ACROSS THE FORECAST AREA.

WHILE THE SURFACE WARM FRONT IS NOT EXPECTED TO SHIFT NORTH OF THE
NY/PA LINE...ELEVATED WARM ADVECTION WILL OVERSPREAD THE FORECAST
AREA BY THIS AFTERNOON WITH SOME WEAK INSTABILITY AND LARGE SCALE
LIFT CONTRIBUTING TO CHANCES OF SCATTERED SHOWERS AND
THUNDERSTORMS. MESO-MODELS INDICATE THE BEST INSTABILITY IN THE FORM
OF 500-1000 J/KG OF MUCAPE AND MID-LEVEL LAPSE RATES IN EXCESS OF
7C/KM WILL DEVELOP ACROSS THE SOUTHERN TIER INTO THE FINGER
LAKES THIS AFTERNOON WHERE THE FORECAST HAS BEEN TWEAKED TO
HIGHLIGHT A LIKELY AREA OF SHOWERS AND THUNDERSTORMS. THE TRIGGER
FOR STORMS WILL LIKELY BE A WEAK LOW TRACKING TOWARD NORTHEAST PA.
BULK SHEAR IS FORECAST TO REACH 40-50KTS HERE WHERE A FEW STORMS MAY
BECOME STRONG. ANY STORMS THAT DO DEVELOP THIS AFTERNOON SHOULD
WEAKEN/DISSIPATE THIS EVENING WITH THE LOST OF DAYTIME HEATING.
TEMPERATURES THIS AFTERNOON WILL MAX OUT IN THE M/U50S FOR MUCH OF
WESTERN NEW YORK WITH U40S/L50S EAST OF LAKE ONTARIO.

MOST AREAS WILL SEE A LULL IN SHOWER ACTIVITY THIS EVENING AFTER
STORMS HAVE WEAKENED. HAVE HELD ONTO LOW CHANCE POPS BECAUSE WE CAN
NOT RULE OUT A FEW SCATTERED/STRAY SHOWERS IN MOIST SOUTHWEST FLOW
ALOFT. ANOTHER ROUND OF WIDESPREAD SHOWERS WILL SPREAD EAST ACROSS
THE FORECAST AREA NEAR OR JUST AFTER THE MIDNIGHT HOUR AS A SURFACE
LOW WILL TRACK ACROSS THE EASTERN GREAT LAKES AHEAD OF A PRETTY
IMPRESSIVE LOOKING SHORTWAVE AND VORT MAX. HAVE INCLUDED CAT POPS
ACROSS MOST MUCH OF THE SOUTHERN TIER AND FINGER LAKES WHERE THE
RAIN WILL MOST LIKELY ARRIVE BY 12Z MONDAY. WHILE LITTLE TO NO
INSTABILITY IS FORECAST WITH THIS SECOND WAVE OF RAIN...THE 00Z 4KM
NAM AND NSSL-WRF BOTH SHOW A SIGNATURE OF A MESOSCALE CONVECTIVE
VORTEX TRACKING ALONG THE NY/PA LINE. CONFIDENCE IS TOO LOW TO
INCLUDE THUNDER AND GUSTY WINDS FOR A FEATURE SUCH AS AN MCV 24
HOURS OUT BUT THIS WILL BE SOMETHING TO WATCH FOR IN FOLLOWING MODEL
RUNS. TEMPS WILL AGAIN SLIP BACK INTO THE 40S TONIGHT WITH CLOUDS
AND RAIN.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
IT WILL BE A WET START TO THE WORK WEEK AS A FAST-MOVING UPPER LEVEL
SHORTWAVE CROSSES NEW YORK STATE FROM THE SOUTHWEST TO NORTHEAST.
WITH THE ACCOMPANYING MID-LEVEL CENTER AND SURFACE TROUGHING
ORIENTED SOUTHWEST-NORTHEAST ACROSS THE FORECAST AREA...STRONG LOW-
LEVEL CONVERGENCE WILL PRODUCE WIDESPREAD RAINFALL WITH HIGHER
TERRAIN OF THE SOUTHERN TIER AND NORTH COUNTRY SEEING AS MUCH AS A
QUARTER TO HALF INCH OF RAINFALL. RAINFALL SHOULD QUICKLY END FROM
WEST TO EAST AS WE MOVE THROUGH THE DAY HOWEVER AS THE SHORTWAVE
RAPIDLY TRACKS OFF TO THE EAST INTO NEW ENGLAND AND LOW-AMPLITUDE
SHORTWAVE RIDGING MOVES OVERHEAD. WHILE THERE WILL BE SOME CLEARING
AS THE SHORTWAVE TROUGH DEPARTS THE PICTURE...LINGERING MOISTURE AND
THE CONTINUED PRESENCE OF A MID-LEVEL TROUGHING ACROSS THE REGION
SUGGESTS THAT WE WILL SEE A DECENT AMOUNT OF CLOUDS HANGING AROUND
THROUGH MONDAY NIGHT EVEN AS THINGS DRY OUT. THE CLOUDY AND SHOWERY
WEATHER WILL KEEP TEMPERATURES ON THE COOL SIDE WITH HIGHS IN THE
LOW TO MID 50S MONDAY WITH LOWS IN THE UPPER 30S TO LOWER 40S MONDAY
NIGHT.

TUESDAY WILL BE A TRANSITION DAY IN BETWEEN SYSTEMS. A WEAK UPPER
LEVEL TROUGH WILL FILL AS IT CROSSES THE AREA...AND THERE IS A
POSSIBILITY THAT THE WEAK LIFT ASSOCIATED WITH THE FEATURE MAY
INTERACT WITH LIMITED LINGERING MOISTURE ACROSS THE AREA TO SPARK A
FEW ISOLATED SHOWERS TUESDAY INTO TUESDAY NIGHT. HOWEVER...GIVEN THE
LACK OF DEEP MOISTURE AND ANY CLEAR FOCUSED LIFT...WILL STICK WITH
LOW CHANCE POPS. LESS EXTENSIVE CLOUD COVER AND SLIGHTLY WARMER
850MB TEMPS SHOULD PRODUCE SURFACE TEMPERATURES THAT WILL RUN A
LITTLE CLOSER TO CLIMO FOR THIS TIME OF YEAR WITH HIGHS IN THE UPPER
50S WITH READINGS AROUND 60 ION THE TYPICALLY WARMER SPOTS.
INCREASING SOUTHERLY FLOW AHEAD OF OUR NEXT SYSTEM SHOULD YIELD
COMPARATIVELY WARMER READINGS TUESDAY NIGHT WITH LOWS IN THE 40S.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
A SIGNIFICANT PATTERN SHIFT WILL BE UNDERWAY AS WE MOVE INTO THE
MIDDLE OF THE WEEK AS THE UPPER LEVEL REGIME OVER NORTH AMERICA
BECOMES SHARPLY MERIDIONAL. A SHARP UPPER LEVEL RIDGE WILL
CONSOLIDATE OVER THE ROCKIES WHILE A POWERFUL SHORTWAVE ROUNDING THE
TOP OF THIS RIDGE AND DROPPING SOUTH ACROSS THE CANADIAN SHIELD WILL
PROCEED TO CARVE A SHARP TROUGH ACROSS THE UPPER MIDWEST AND GREAT
LAKES ON WEDNESDAY. FALLING HEIGHTS ACROSS THE LOWER GREAT LAKES
WILL INCREASE SHOWER CHANCES WEDNESDAY INTO WEDNESDAY
NIGHT...HOWEVER BEST SYNOPTIC FORCING WILL REMAIN TO OUR WEST ACROSS
THE UPPER GREAT LAKES AND A FRONTAL SYSTEM LINGERING JUST OFF THE
EASTERN SEABOARD WILL DEPRIVE WESTERN/NORTH-CENTRAL NEW YORK OF
DEEPER MOISTURE...SO AT THIS POINT IT APPEARS ACTIVITY WILL BE
SCATTERED AT BEST. INCREASING SOUTHERLY FLOW AHEAD OF THE
APPROACHING TROUGH WILL BOOST TEMPERATURES INTO THE 60S ON WEDNESDAY
WITH LOWS IN THE 40S WEDNESDAY NIGHT.

THURSDAY LOOKS MORE PROMISING IN TERMS OF WIDESPREAD PRECIPITATION AS
THE UPPER LEVEL TROUGH CUTS OFF INTO A DEEP UPPER LEVEL LOW THAT
MOVES ACROSS THE CENTRAL APPALACHIANS WITH TROUGHING THAT EXTENDS
NORTH INTO THE LOWER GREAT LAKES. THE PRESENCE OF THE TROUGHING IN
THE UPPER LEVELS AND A MID-LEVEL LOW OVERHEAD ALONG WITH INCREASING
EASTERLY RETURN FLOW OFF THE ATLANTIC SHOULD PROMOTE THE DEVELOPMENT
OF WIDESPREAD SHOWERS THURSDAY INTO THURSDAY NIGHT. IT IS WORTH
NOTING THAT THE 00Z RUN OF THE ECMWF HAS COME IN SLIGHTLY WARMER
ACROSS WESTERN NY WITH THE COLDEST AIR REMAINING WELL TO OUR
SOUTHWEST ACROSS THE OHIO VALLEY. THUS AT THIS POINT SNOWFALL NO
LONGER APPEARS TO BE A CONCERN.

COOL AND SHOWERY WEATHER WILL LIKELY PERSIST THROUGH THE END OF THE
WEEK AS THE UPPER LEVEL LOW ENCOUNTERS A STRONG BLOCKING RIDGE OVER
THE WESTERN ATLANTIC AND SUBSEQUENTLY LINGERS ACROSS THE MID-
ATLANTIC AND NORTHEASTERN STATES. THE HEAVILY MODIFIED MARITIME
AIRMASS IN PLACE WILL KEEP TEMPERATURES RELATIVELY MILD IN SPITE OF
THE PRESENCE OF THE UPPER LOW WITH HIGHS GENERALLY RANGING FROM THE
MID 50S TO LOWER 60S AND LOWS IN THE LOW TO MID 40S FROM THURSDAY
THROUGH SATURDAY.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
A WARM FRONT WILL CONTINUE TO SPREAD A BAND OF STEADY RAIN NORTHEAST
ACROSS THE FORECAST AREA THIS MORNING. CEILINGS WILL REMAIN A MIX OF
LOWER END MVFR FOR MOST SITES WITH IFR/LIFR ACROSS THE HIGHER
TERRAIN OF THE SOUTHERN TIER. THE BACK EDGE OF THE WIDESPREAD RAIN
WILL SHIFT EAST ACROSS EASTERN NEW YORK THROUGH NOON WITH SOME
DRY TIME OUTSIDE OF STRAY/SCATTERED SHOWERS THIS AFTERNOON.

THERE IS A CHANCE OF CONVECTION THIS AFTERNOON MAINLY TOWARD THE
NY/PA BORDER AS INSTABILITY DEVELOPS NEAR A STALLED WARM FRONT. THIS
MAY IMPACT KJHW BUT CONFIDENCE IS TOO LOW AT THIS TIME TO INCLUDE
VCTS IN THE TAF.

SCATTERED SHOWERS WILL CONTINUE TO BE POSSIBLE THIS EVENING INTO THE
OVERNIGHT AHEAD OF A SECOND ROUND OF WIDESPREAD RAIN THAT WILL
OVERSPREAD MUCH OF THE FORECAST AREA LATE SUNDAY NIGHT. THIS WILL
LIKELY LOWER CIGS TO IFR FOR MOST.

OUTLOOK...
MONDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
TUESDAY...MAINLY VFR.
WEDNESDAY AND THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.

&&

.MARINE...
A EAST-NORTHEASTERLY FLOW WILL FRESHEN TODAY AS A LOW PRESSURE
SYSTEM TRACKING OUT OF THE OHIO VALLEY TRACKS TOWARDS THE LOWER
GREAT LAKES. AS THE EAST-NORTHEASTERLY WINDS STRENGTHEN TO NEAR 20
KNOTS...WAVES WILL BUILD IN EXCESS OF 4 FEET ON THE WEST END OF LAKE
ONTARIO LATER THIS MORNING...PROMPTING A SMALL CRAFT ADVISORY
THROUGH THE DAY.

A GENERALLY WEAK PRESSURE GRADIENT WILL RESULT IN TRANQUIL
CONDITIONS ON THE LAKES FROM TONIGHT INTO THE MID PART OF NEXT WEEK.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LOZ042.

&&

$$

SYNOPSIS...SMITH/TMA
NEAR TERM...SMITH
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...SMITH/TMA
MARINE...SMITH/TMA



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