Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 242126
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
526 PM EDT SUN APR 24 2016

.SYNOPSIS...
A WARM FRONT WILL MOVE INTO THE REGION OVERNIGHT AND THEN STALL NEAR
THE NY THRUWAY ON MONDAY. THE WARM FRONT WILL BRING AN INCREASE IN
CLOUD COVER TONIGHT AND EVENTUALLY A FEW SHOWERS TO THE EASTERN LAKE
ONTARIO REGION ON MONDAY. A WAVE OF LOW PRESSURE WILL THEN MOVE
ALONG THE FRONT MONDAY NIGHT AND TUESDAY WITH PERIODS OF RAIN AND
MUCH COOLER TEMPERATURES. DRY WEATHER WILL RETURN BY WEDNESDAY AS
HIGH PRESSURE BUILDS INTO THE GREAT LAKES.

&&

.NEAR TERM /THROUGH MONDAY/...
VISIBLE SATELLITE IMAGERY SHOWING THE LEADING EDGE OF THE MID LEVEL
CLOUD DECK ERODING AS IT TRIES TO MOVE INTO NEW YORK WITH STRONG
SUBSIDENCE AND DRY AIR STILL IN PLACE. EXPECT A MIX OF SUN AND
CLOUDS THROUGH THE REST OF THE AFTERNOON BEFORE THICKER MID LEVEL
CLOUDS MOVE IN THIS EVENING. TEMPERATURES WILL TOP OUT AROUND 60
FROM THE NIAGARA FRONTIER TO BUFFALO...WITH SOME MID 60S POSSIBLE IN
A FEW OF THE WARMER SOUTHERN TIER VALLEYS...AND MID 50S ACROSS THE
NORTH COUNTRY. THE LIGHT SYNOPTIC SCALE WINDS AND STRONG
DIFFERENTIAL HEATING HAS ALLOWED LOCAL LAKE BREEZES TO FORM...WITH
WINDS ONSHORE ALONG ALL THE LAKESHORES THROUGH LATE AFTERNOON AND
MUCH COOLER TEMPERATURES WITHIN A FEW MILES OF THE LAKE.

TONIGHT THE WARM FRONT WILL CONTINUE TO DEVELOP AND SHARPEN ACROSS
SOUTHERN ONTARIO INTO WESTERN AND CENTRAL NY. THE TIGHTENING MID
LEVEL TEMPERATURE GRADIENT IN THE FRONTOGENESIS REGIME COMBINED WITH
INCREASING ISENTROPIC UPGLIDE AND MOISTURE WILL BRING THICKENING AND
LOWERING MID LEVEL CLOUDS OVERNIGHT. THE GFS CONTINUES TO BE MORE
AGGRESSIVE AND FARTHER SOUTH IN DEVELOPING LIGHT RAIN ALONG THE WARM
FRONT LATE TONIGHT AND EARLY MONDAY. ALL OTHER GUIDANCE INCLUDING
THE NAM...CANADIAN REGIONAL...AND NAM-RR ALL KEEP THE WARM FRONT
MAINLY DRY THROUGH MONDAY MORNING. GIVEN THE VERY DRY LOW LEVELS IN
PLACE ACROSS NY...THE MAINLY DRY MODEL CONSENSUS SEEMS REASONABLE
WITH PLENTY OF SUB-CLOUD EVAPORATION EXPECTED ALONG THE DEVELOPING
WARM FRONT. WITH THIS IN MIND...WILL ADJUST TO A MAINLY DRY FORECAST
THROUGH MONDAY MORNING.

THE INCREASE IN CLOUD COVER AND INCREASING WARM ADVECTION WILL KEEP
TEMPERATURES MILDER TONIGHT THAN LAST NIGHT...WITH LOWS IN THE LOWER
40S ACROSS WESTERN NY AND UPPER 30S CENTRAL NY...WITH LOW TO MID 30S
ACROSS THE NORTH COUNTRY.

ON MONDAY THE MID LEVEL WARM FRONT WILL PUSH NORTHEAST ACROSS THE
AREA AND STALL NEAR THE NORTH SHORE OF LAKE ONTARIO TO THE EASTERN
LAKE ONTARIO REGION BY LATE AFTERNOON. ISENTROPIC UPGLIDE WILL
CONTINUE TO INCREASE ACROSS THE SHARPENING FRONTAL ZONE...AND SHOULD
BECOME STRONG ENOUGH BY AFTERNOON TO ALLOW SOME LIGHT RAIN TO REACH
THE GROUND ACROSS THE EASTERN LAKE ONTARIO REGION. FARTHER WEST...A
DEVELOPING MID LEVEL DRY SLOT TO THE SOUTH OF THE WARM FRONT SHOULD
KEEP MOST AREAS DRY ON MONDAY AND ALLOW FOR SOME SUNSHINE IN THE
AFTERNOON...ESPECIALLY CLOSER TO THE PA STATE LINE.

WHILE THE MID LEVEL WARM FRONT WILL LIFT TO THE NORTH SHORE OF LAKE
ONTARIO...THE SURFACE FRONTAL BOUNDARY WILL STALL NEAR THE NY
THRUWAY ON MONDAY. THE FRONT WILL HAVE A VERY SHARP TEMPERATURE
GRADIENT ACROSS IT...WITH TEMPERATURES CLIMBING INTO THE LOW TO MID
70S ACROSS THE SOUTHERN TIER ON THE WARM SIDE. TO THE NORTH OF THE
FRONT...TEMPERATURES WILL REMAIN IN THE LOW TO MID 50S NORTH OF THE
THRUWAY...AND ONLY MID 40S ALONG THE SOUTH SHORE OF LAKE ONTARIO
WITH INCREASING NORTHEAST FLOW OFF THE LAKE. THIS WILL YIELD A 30
DEGREE TEMPERATURE GRADIENT FROM THE SOUTH SHORE OF LAKE ONTARIO TO
THE PA STATE LINE.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
WIDESPREAD RAIN SHOWERS ARE EXPECTED MONDAY NIGHT INTO TUESDAY AS A
WEAK SURFACE LOW/WAVE IS FORECAST TO SHIFT EAST ALONG A STATIONARY
FRONT STRETCHED FROM CENTRAL LOWER MICHIGAN ACROSS LAKE ERIE INTO
WESTERN NEW YORK. NORTHEAST WINDS ON THE NORTH SIDE OF THE FRONT AND
SOUTHWEST WINDS TO THE SOUTH WILL CONTINUE A VERY TIGHT NORTH-SOUTH
TEMPERATURE GRADIENT OVER THE FORECAST EVENT. THE 12Z 4KM NAM
INDICATES SOME WEAK ELEVATED INSTABILITY WILL DEVELOP IN THE WARMER
AIR ALONG AND SOUTH OF THE FRONT WHERE 500-1000 J/KG OF MUCAPE IS
FORECAST. HAVE ADDED A CHANCE OF THUNDERSTORMS FROM BUFFALO SOUTH
INTO THE NY SOUTHERN TIER MONDAY NIGHT.

QPF TOTALS WILL RUN 0.5-0.75 INCH WITH THE HIGHER TOTALS RUNNING
SOUTHWEST OF KROC WHERE PWATS ARE FORECAST TO RUN ABOUT 1.1 INCHES
OR NEAR THE 90TH PERCENTILE FOR LATE APRIL. LOW TEMPERATURES WILL
ONLY SLIP INTO THE U40S TO AROUND 50 SOUTH OF THE FRONT WITH U30S-
M40S ON THE LAKE PLAINS SOUTH OF LAKE ONTARIO WITH M30S IN THE
NORTH COUNTY POSSIBLY DROPPING INTO THE L30S IN THE SAINT LAWRENCE
VALLEY. THE SAINT LAWRENCE VALLEY WILL HAVE TO BE CLOSELY WATCHED
FOR A POTENTIAL OF ANY ICE/SNOW IF THE NORTHEAST FLOW PUSHES
SURFACE TEMPS BELOW FREEZING BENEATH A SHARP INVERSION ALOFT.

A MID-LEVEL SHORTWAVE TROUGH AND VORT MAX WILL CROSS THE EASTERN
GREAT LAKES ON TUESDAY. THIS SHOULD FORCE THE STATIONARY FRONT SOUTH
OF THE NY/PA BORDER AS THE SURFACE LOW TRACKS EAST. BY TUESDAY
AFTERNOON POPS FALL TO LOW/SLIGHT CHANCE AS DRY ARCTIC SOURCED AIR
BEGINS TO WORK SOUTH IN THE WAKE OF THE FRONT. THE COMBINATION OF
THE NORTHERLY FLOW...CLOUD COVER AND SHOWERS WILL KEEP HIGH
TEMPERATURES ON TUESDAY FOR MOST LIMITED TO THE 40S. THE EXCEPTION
WILL BE CLOSER TO THE NY/PA LINE WHERE HIGHS MAY SNEAK INTO THE
U50S/L60S TUESDAY MORNING BEFORE THE FRONT PUSHES SOUTH.

THE DRY ARCTIC SOURCED AIRMASS FLOOD SOUTH ACROSS THE GREAT LAKES
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. 850MB TEMPS WILL FALL TO
WITHIN A FEW DEGREES EITHER SIDE OF 0C DURING THIS PERIOD WHICH WILL
KEEP SURFACE TEMPERATURES 5-10 DEGREES F BELOW NORMAL DESPITE MAINLY
CLEAR SKIES. LOWS TUESDAY AND WEDNESDAY SHOULD DIP INTO THE M/L30S
FOR MOST WITH U20S ACROSS THE NORTH COUNTY. HIGHS ON WEDNESDAY WILL
STRUGGLE TO REACH 50 EXCEPT FOR CLOSER TO THE NY/PA LINE WHERE
L/M50S WILL BE POSSIBLE.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS WE MOVE INTO THE LATTER PORTION OF THE WEEK THE UPPER LEVEL
PATTERN WILL FEATURE A BROAD ZONAL FLOW ACROSS THE EASTERN U.S.. ON
THURSDAY WESTERN/NORTH-CENTRAL NEW YORK WILL BE LOCATED WITHIN A
BROAD BAROCLINIC ZONE IN BETWEEN COLDER AIR ASSOCIATED WITH A
DEEP AND PERSISTENT LOW OVER LABRADOR AND WARM...MOIST AND
UNSTABLE GULF AIR TO OUR SOUTH ACROSS THE OHIO VALLEY. THIS
BAROCLINIC ZONE WILL SERVE AS THE FOCUS FOR THE DEVELOPMENT OF
SHOWERS AND POSSIBLY THUNDERSTORMS AS AN INVERTED SURFACE TROUGH
MOVES ALONG IT ON THURSDAY...HOWEVER THE NORTHWARD EXTENT OF THE
TROUGH IS STILL IN QUESTION AS CANADIAN HIGH PRESSURE MAY KEEP THE
TROUGHING SUPPRESSED FAR ENOUGH SOUTH TO KEEP ACTIVITY MAINLY
SOUTH OF THE FORECAST AREA. THE ECMWF IS TRENDING SOUTH WITH THIS
FEATURE AND ASSOCIATED PRECIP AND EVEN THE GFS IS BEGINNING TO
TREND FARTHER SOUTH AS WELL. FOR THE TIME BEING WILL MAINTAIN
CHANCE POPS ACROSS THE FORECAST AREA WITH HIGHEST POPS NEAR THE PA
BORDER PENDING FUTURE MODEL TRENDS AND GREATER CLARITY.

MODELS CONTINUE TO EXHIBIT DIFFERENCES MOVING THROUGH FRIDAY AND
INTO THE WEEKEND WITH THE OPERATIONAL GFS/GEM MODELS ALONG
WITH THE GFS ENSEMBLE MEAN BEING MUCH STRONGER WITH THE
AFOREMENTIONED CANADIAN HIGH...BUILDING IT INTO THE LOWER GREAT
LAKES TO THE MID- ATLANTIC STATES AND ESSENTIALLY LEAVING OUR AREA
DRY THROUGH THE WEEKEND. ON THE OTHER HAND THE ECMWF...WHICH IS
WEAKER WITH THE UPSTREAM RIDGING ALOFT AND SURFACE HIGH FROM THE
OUTSET...DRIVES A DEEPENING SURFACE CYCLONE FROM THE HIGH PLAINS
TO THE GREAT LAKES OVER THE WEEKEND...WITH A STRENGTHENING WARM
FRONTAL BOUNDARY SERVING AS THE FOCUS FOR SHOWERS AND
THUNDERSTORMS ON SUNDAY. GIVEN THESE DIAMETRICALLY OPPOSED
SOLUTIONS...THE BEST WE CAN GO WITH FOR NOW IS A LOW CHANCE OF
SHOWERS ON SUNDAY.

REGARDING TEMPERATURES...GIVEN THAT THE LOWER GREAT LAKES WILL BE
LOCATED DIRECTLY IN BETWEEN COLDER CANADIAN AIR TO THE NORTH AND
WARM/MOIST GULF AIR TO THE SOUTH...LOOK FOR TEMPERATURES TO RUN
RIGHT AROUND CLIMATOLOGICAL AVERAGES FOR THE END OF APRIL WITH HIGHS
IN THE UPPER 50S AND LOWS IN THE UPPER 30S TO LOWER 40S.

&&

.AVIATION /22Z SUNDAY THROUGH FRIDAY/...
VFR WILL PREVAIL FOR THE 18Z TAF CYCLE. PATCHES OF MID LEVEL CLOUDS
WILL CONTINUE TO CROSS THE AREA THROUGH LATE AFTERNOON. THE MID
LEVEL CLOUDS WILL THICKEN AND LOWER TONIGHT AS A WARM FRONT DEVELOPS
ACROSS THE REGION. A FEW WIDELY SCATTERED LIGHT SHOWERS MAY DEVELOP
NEAR LAKE ONTARIO BY MONDAY MORNING ALONG AND NORTH OF THE WARM
FRONTAL BOUNDARY. SHOWERS WILL INCREASE IN COVERAGE MONDAY AFTERNOON
ACROSS THE EASTERN LAKE ONTARIO REGION NEAR THE WARM FRONT...WHILE
THE REST OF THE AREA REMAINS MAINLY DRY. CIGS WILL CONTINUE TO
REMAIN VFR ON MONDAY WITH RELATIVELY DRY LOW LEVELS.

OUTLOOK...
MONDAY NIGHT...SHOWERS AND SCATTERED THUNDERSTORMS WITH MVFR/IFR.
TUESDAY...MVFR/IFR WITH SHOWERS IN THE MORNING...IMPROVING TO VFR
BY TUESDAY EVENING.
WEDNESDAY...VFR.
THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
FRIDAY...VFR.

&&

.MARINE...
HIGH PRESSURE AND LIGHT SYNOPTIC SCALE FLOW HAS ALLOWED LOCAL LAKE
BREEZE CIRCULATIONS TO DEVELOP THIS AFTERNOON WITH ONSHORE BREEZES
AND FLAT WAVE ACTION.

HIGH PRESSURE WILL BECOME CENTERED OVER NORTHWEST ONTARIO MONDAY AND
TUESDAY AND STRENGTHEN WITH A FRONTAL ZONE STALLING FROM LAKE ERIE
TO CENTRAL/EASTERN NY. NORTHEAST FLOW WILL INCREASE TO THE NORTH OF
THE FRONT ON MONDAY OVER LAKE ONTARIO...PRODUCING SMALL CRAFT
ADVISORY CONDITIONS AT THE WEST END OF THE LAKE. THE NORTHEAST WINDS
WILL INCREASE FURTHER MONDAY NIGHT AND TUESDAY AS A WAVE OF LOW
PRESSURE RUNS EAST ALONG THE FRONT. THIS WILL BRING SOLID SMALL
CRAFT ADVISORY CONDITIONS TO MOST OF THE SOUTH SHORE OF LAKE
ONTARIO. WINDS WILL BE LIGHTER ON LAKE ONTARIO THROUGH THE PERIOD.

&&

.FIRE WEATHER...
FINE FUELS REMAIN VERY DRY ACROSS MOST OF WESTERN...CENTRAL...AND
NORTHERN NY AFTER ABOUT 11 DAYS OF LITTLE TO NO RAINFALL.

THIS AFTERNOON HIGH PRESSURE WILL BRIEFLY BUILD ACROSS NEW YORK
STATE. A VERY DRY AIRMASS AND DAYTIME HEATING WILL ALLOW FOR
MINIMUM AFTERNOON RELATIVE HUMIDITY TO DROP TO THE 20-25 PERCENT
RANGE INLAND FROM THE GREAT LAKES SHORELINES. WINDS WILL BE ON THE
LIGHT SIDE HOWEVER WITH A WEAK PRESSURE GRADIENT IN PLACE...
GENERALLY 10 MPH OR LESS. EXPECT LOCAL LAKE BREEZES TO DEVELOP
THIS AFTERNOON WITH WINDS BECOMING ONSHORE ALONG THE GREAT LAKES
SHORELINES.

HUMIDITY WILL BE HIGHER MONDAY AFTERNOON AS A MORE MOIST AIRMASS
BEGINS TO MOVE INTO THE REGION. THIS WILL BE FOLLOWED BY A
WIDESPREAD WETTING RAIN MONDAY NIGHT INTO TUESDAY AS A COLD FRONT
AND WAVE OF LOW PRESSURE CROSS THE REGION.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 5 PM MONDAY TO 8 PM EDT TUESDAY FOR
         LOZ043.
         SMALL CRAFT ADVISORY FROM 9 AM MONDAY TO 8 PM EDT TUESDAY
         FOR LOZ042.

&&

$$

SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK
SHORT TERM...SMITH
LONG TERM...WOOD
AVIATION...HITCHCOCK
MARINE...HITCHCOCK
FIRE WEATHER...HITCHCOCK



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