Special Weather Statement, NWS Buffalo, NY

Area Forecast Discussion
National Weather Service Buffalo NY
241 PM EDT SUN JUL 31 2016

.SYNOPSIS...
An upper level disturbance will drift slowly across the area
through tonight with scattered showers and thunderstorms which
will linger into Monday. Dry weather will then return for Tuesday
through the middle of the week as high pressure builds into the
region.

&&

.NEAR TERM /THROUGH MONDAY/...
For the remainder of this afternoon, the main concern continues to
be the potential for heavy rain. Mesoscale guidance (12Z ARW/NMM and
the latest HRRR) now captures convection from earlier this morning,
which increases forecast confidence some even though convection
continues to develop along subtle boundaries. The main synoptic
feature driving this is a slow moving upper level trough across the
Great Lakes Region. The flow beneath 700mb is very weak so storms
have and will continue to be very slow moving, with the potential to
produce locally heavy rainfall. Precipitable water values are around
1.5 inches as shown by the KBUF sounding, which is moderate but
ample to produce flooding. Using a blend of radar trends and model
consensus suspect the greatest potential for locally heavy rainfall
extends from the Wyoming Hills to the Western Southern Tier. This
area got some sunshine this morning, and there is a northerly lake
breeze which may help provide a focus for this activity. This
potential will diminish this evening when instability decreases.

The upper level feature will slowly drift east overnight, with a
weak area of low pressure passing to the south and high pressure
to the north. There will be a weak pressure gradient and generally
light winds, resulting in the potential for radiation fog. Model
guidance forecasts variable but considerable mid and high clouds
across the region, which will inhibit radiational cooling and fog,
but any breaks could quickly be followed by fog development. This
will especially be the case in areas which get rainfall today,
such as the Niagara Frontier and Western Southern Tier. Lows will
range from the lower 60s across the interior to the mid to upper
60s across the lake plains.

On Monday, the trough axis will still be across Eastern New York
which will probably result in more diurnally driven showers and
thunderstorms. These should be most widespread across the Eastern
Lake Ontario region, and interior portions of the Southern Tier.
Storm motion will still be slow, but the air mass will be drier with
precipitable water values around 1.25 inches. Like today, storms
will be hit or miss with many locations missing out on the rain all
together. Expect high temperatures to range from the upper 70s
across the interior to the lower 80s across the lake plains where
there should be a bit more sunshine.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
The mid-level trough and low/mid-level moisture axis will shift east
of New York into New England Monday night. Only forecasting a
low/slight chance of showers east of Lake Ontario as the moisture
and synoptic forcing departs. All other locations will be dry with
skies clearing west to east. Upper level ridging and surface high
pressure will build across the forecast area on Tuesday. Expect most
areas to remain dry with plenty of sunshine but 12z EC/GFS models
are developing some diurnal showers/isolated storm again east of
Lake Ontario. Have held POPs to slight chance due to ridging
building overhead. Upper level ridging and surface high pressure
will maintain control of our weather Tuesday night through Wednesday
with dry conditons and mainly clear skies.

Warm advection and ridging building aloft will help boost our
temperatures back above normal this period. Highs will range from
the low to mid 80s Tuesday with northeasterly winds holding the Lake
Erie lake breeze at bay. This will help temperatures in downtown
Buffalo to reach higher than surrounding towns. On Wednesday, Highs
will warm into the mid to upper 80s as winds veer around to
Southwest. This should allow return of the Lake Erie breeze with
warmer spots occuring across the Genesee Valley and and Lake Ontario
lake plains inland of a weak Lake Ontario lake breeze. Low
temperatures will range from mid 60s near the lakes to mid 50s
inland across the higher terrain Monday night and Tuesday night.
Humidity levels should remain comfortable through Tuesday then
increase with developing southwesterly flow on Wednesday. This will
make for much more mild overnight temperatures Wednesday night with
some locations not falling below 70.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
A broad upper level ridge will maintain its grip over much of the
United States with building warmth over our region. 850 mb
temperatures will push into the upper teens Celsius over our region
Thursday and Friday, which will bring mid 80s to lower 90s.
Warmest readings will of course be in the typical downslope Genesee
Valley and northern Finger Lakes locations.

Both the ECMWF and GFS are into good agreement with the upper level
trough pushing a cold front across the CWA between 00Z Saturday and
12Z Saturday. On Friday ahead of the cold front a gusty southwest
lake breeze off Lake Erie will likely maintain the metro Buffalo
area dry, while providing a boundary for a few afternoon showers and
thunderstorms. Thunderstorms will become likely Friday evening and
overnight ahead of the cold front, as enhanced lift from the nearing
shortwave into a very moist (PWATS nearing 2 inches) and unstable
environment occurs. Given the instability parameters, and evening
timing of convection, there is a chance that some of these storms
could become strong.

Will maintain the very warm temperatures through the day Friday,
though a little cooler over metro Buffalo and northern Jefferson
County where the lake breeze will be established. Following the cold
front passage Saturday will be a bit cooler with highs in the low to
mid 80s. With the upper level low nearby, and cyclonic flow aloft
over northern NYS, will have a chance for showers, and an isolated
thunderstorm Saturday over the Finger Lakes region, and eastern
Lake Ontario region.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
The potential for thunderstorms will be the primary concern for
aviation through this evening. Model guidance and radar trends
suggest the best chance for thunderstorms will be through late
afternoon at ROC/JHW, however it is difficult to completely rule
out a thunderstorm at any location. Thunderstorms are slow moving,
and may last for an hour or two, with MVFR or lower conditions.

Tonight, the main concern is the potential for low stratus and
fog. This will largely depend on how much mid and high level
clouds clear out, and which locations receive rainfall this
afternoon. Generally speaking MOS guidance is very pessimistic
tonight, but for the 18Z TAFS IFR or lower conditions are only
forecast at JHW due to its climatologically and IAG due to
rainfall late this morning. There is a potential for locally dense
fog tonight with VSBY below a half mile, and this is likely to
occur if skies clear out since winds will be light and moisture
will be in place.

Fog and stratus should gradually dissipate Monday morning, with
conditions generally improving to VFR. Showers and thunderstorms
are possible in the afternoon with localized MVFR or lower
conditions at times.

Outlook...

Monday night through Thursday...VFR.
Friday...Mainly VFR. A chance of showers and thunderstorms.

&&

.MARINE...
An extended period of northeast winds continues this afternoon but
winds and waves will likely remain just shy of Small Craft
Advisory criteria. Northeast winds back off some tonight as high
pressure builds toward the region. Light northeast winds will
continue Monday and Tuesday before turning more southerly by
midweek.

&&

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

&&

SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...SMITH
LONG TERM...CHURCH
AVIATION...APFFEL
MARINE...APFFEL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BUFFALO NY
857 AM EDT SUN JUL 31 2016

NYZ001>008-010>014-019>021-085-011300-
NIAGARA-ORLEANS-MONROE-WAYNE-NORTHERN CAYUGA-OSWEGO-JEFFERSON-LEWIS-
NORTHERN ERIE-GENESEE-WYOMING-LIVINGSTON-ONTARIO-CHAUTAUQUA-
CATTARAUGUS-ALLEGANY-SOUTHERN ERIE-
857 AM EDT SUN JUL 31 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN AND NORTH CENTRAL NEW
YORK.

.DAY ONE...TODAY AND TONIGHT.

SCATTERED THUNDERSTORMS WILL DEVELOP TODAY. ANY STORMS THAT
DEVELOP WILL BE VERY SLOW MOVING AND MAY PRODUCE VERY HEAVY
RAINFALL AND FLOODING IN A FEW LOCALIZED AREAS.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

THIS PRODUCT...ALONG WITH OTHER WATCHES...WARNINGS...ADVISORIES...
AND STATEMENTS ISSUED BY THE NATIONAL WEATHER SERVICE OFFICE IN
BUFFALO CAN BE FOUND ON THE INTERNET AT HTTP://WWW.WEATHER.GOV/BUF

LEZ020-040-041-LOZ030-042>045-062>065-SLZ022-024-011300-
UPPER NIAGARA RIVER AND BUFFALO HARBOR-
LAKE ERIE NEARSHORE WATERS FROM RIPLEY TO DUNKIRK-
LAKE ERIE NEARSHORE WATERS FROM DUNKIRK TO BUFFALO-
LOWER NIAGARA RIVER-
LAKE ONTARIO NEARSHORE WATERS FROM THE NIAGARA RIVER TO HAMLIN BEACH-
LAKE ONTARIO NEARSHORE WATERS FROM HAMLIN BEACH TO SODUS BAY-
LAKE ONTARIO NEARSHORE WATERS FROM SODUS BAY TO MEXICO BAY-
LAKE ONTARIO NEARSHORE WATERS FROM MEXICO BAY TO THE SAINT LAWRENCE
RIVER-
LAKE ONTARIO OPEN WATERS FROM THE NIAGARA RIVER TO HAMLIN BEACH-
LAKE ONTARIO OPEN WATERS FROM HAMLIN BEACH TO SODUS BAY-
LAKE ONTARIO OPEN WATERS FROM SODUS BAY TO MEXICO BAY-
LAKE ONTARIO OPEN WATERS FROM MEXICO BAY TO THE SAINT LAWRENCE RIVER-
SAINT LAWRENCE RIVER FROM CAPE VINCENT TO OGDENSBURG-
SAINT LAWRENCE RIVER FROM OGDENSBURG TO SAINT REGIS-
857 AM EDT SUN JUL 31 2016

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE NEW YORK WATERS OF LAKE
ERIE...LAKE ONTARIO...AND THE SAINT LAWRENCE RIVER.

.DAY ONE...TODAY AND TONIGHT.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

THIS PRODUCT...ALONG WITH OTHER WATCHES...WARNINGS...ADVISORIES...
AND STATEMENTS ISSUED BY THE NATIONAL WEATHER SERVICE OFFICE IN
BUFFALO CAN BE FOUND ON THE INTERNET AT HTTP://WWW.WEATHER.GOV/BUF

APFFEL

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BUFFALO NY
221 PM EDT SUN JUL 31 2016

NYZ019-020-311915-
CATTARAUGUS-CHAUTAUQUA-
221 PM EDT SUN JUL 31 2016

...A STRONG THUNDERSTORM WILL BRING HEAVY RAIN TO SOUTHWESTERN
CATTARAUGUS AND CHAUTAUQUA COUNTIES...

AT 218 PM EDT...A LINE OF STRONG THUNDERSTORMS WAS MOVING INTO THE
WESTERN SOUTHERN TIER. THESE THUNDERSTORMS ARE VERY SLOW MOVING AND
HAVE THE POTENTIAL TO PRODUCE LOCALLY HEAVY RAINFALL. THUNDERSTORMS
WILL CONTINUE THROUGH LATE AFTERNOON, AND THEN TAPER OFF THIS
EVENING.

THIS INCLUDES JAMESTOWN AND SURROUNDING AREAS, AS WELL AS INTERSTATE
86 BETWEEN EXITS 4 AND 21.

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY CAUSE
LOCALIZED FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

LAT...LON 4225 7976 4240 7876 4200 7867 4200 7976
TIME...MOT...LOC 1818Z 271DEG 7KT 4216 7931

APFFEL

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BUFFALO NY
315 PM EDT SUN JUL 31 2016

NYZ013-014-312015-
ONTARIO-LIVINGSTON-
315 PM EDT SUN JUL 31 2016

...AN AREA OF THUNDERSTORMS BRING HEAVY RAINFALL TO WESTERN ONTARIO
AND EASTERN LIVINGSTON COUNTIES...

AT 313 PM EDT...THUNDERSTORMS WERE CLUSTERED NEAR LIMA...OR 10 MILES
EAST OF GENESEO...MOVING EAST AT 15 MPH. THESE STORMS ARE PRODUCING
VERY HEAVY RAINFALL.

LOCATIONS IMPACTED INCLUDE...
CANANDAIGUA...DANSVILLE...AVON...CONESUS...BRISTOL...LIMA...
BLOOMFIELD...NAPLES...HONEOYE AND HEMLOCK.

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY CAUSE
LOCALIZED FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

LAT...LON 4252 7783 4294 7775 4293 7714 4276 7723
      4276 7731 4273 7734 4267 7736 4267 7737
      4258 7737 4258 7766 4253 7766 4253 7772
      4252 7772
TIME...MOT...LOC 1913Z 291DEG 13KT 4285 7762

APFFEL

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BUFFALO NY
406 PM EDT SUN JUL 31 2016

NYZ019-020-085-312100-
SOUTHERN ERIE-CATTARAUGUS-CHAUTAUQUA-
406 PM EDT SUN JUL 31 2016

...AN AREA OF THUNDERSTORMS BRINGING HEAVY RAINFALL TO SOUTH CENTRAL
ERIE...NORTHWESTERN CATTARAUGUS AND EAST CENTRAL CHAUTAUQUA
COUNTIES...

AT 403 PM EDT...THUNDERSTORMS WERE CLUSTERED ALONG A LINE FROM
CASSADAGA TO GOWANDA...MOVING NORTHEAST AT 30 MPH.

LOCATIONS IMPACTED INCLUDE...
GOWANDA...CONCORD...COLLINS...STOCKTON...DAYTON...ARKWRIGHT...
FORESTVILLE...CASSADAGA...PERRYSBURG AND SILVER CREEK RESERVOIR.

TORRENTIAL RAINFALL IS ALSO OCCURRING WITH THIS STORM...AND MAY CAUSE
LOCALIZED FLOODING. DO NOT DRIVE YOUR VEHICLE THROUGH FLOODED
ROADWAYS.

LAT...LON 4228 7932 4235 7944 4261 7881 4253 7867
TIME...MOT...LOC 2003Z 243DEG 26KT 4236 7923

TMA