Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 040542
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
142 AM EDT MON MAY 4 2015

.SYNOPSIS...
HIGH PRESSURE WILL SLIDE OFF THE MID ATLANTIC COAST OVERNIGHT
WHICH WILL SET UP A BREEZY AND WARM RETURN FLOW TODAY. A COLD
FRONT WILL CROSS THE AREA THIS EVENING THROUGH TUESDAY AND BRING
SHOWERS AND POSSIBLY A FEW THUNDERSTORMS. TEMPERATURES WILL ONLY
COOL FOR ONE DAY BEHIND THE COLD FRONT WITH PLENTY OF WARMTH
RETURNING FOR THE SECOND HALF OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
NO MAJOR CHANGES TO THE ONGOING FORECAST FOR THIS LATE EVENING
UPDATE.

TONIGHT WILL FEATURE CLEAR SKIES. EXPECT GOOD RADIATIONAL COOLING
CONDITIONS FOR THE FIRST HALF OF THE NIGHT...BUT A MODEST SOUTHERLY
FLOW WILL DEVELOP FROM W-E LATE TONIGHT AS THE SURFACE HIGH SLIDES
OFF THE MID ATLANTIC COAST. LOWS SHOULD RANGE FROM THE MID TO UPPER
40S ACROSS THE NORTH COUNTRY AND INTERIOR VALLEYS...TO THE LOWER TO
MID 50S ELSEWHERE.

MODEL GUIDANCE CONTINUES TO INDICATE THAT WEAK SHORTWAVE AND
ASSOCIATED COLD FRONT WILL APPROACH THE REGION FROM THE WEST ON
MONDAY. IN ADVANCE OF THIS...WINDS WILL PICK UP WITH A 925MB WINDS
FORECAST TO INCREASE TO AROUND 30 KTS. THIS SHOULD MIX DOWN SURFACE
GUSTS OF 25 TO 30 MPH WHICH SHOULD KEEP THE BOUNDARY LAYER WELL
MIXED AND DELAY THE START OF ANY SHOWERS ASSOCIATED WITH THE FRONT.
SOME HIGH RESOLUTION GUIDANCE (NAM/RGEM) SHOWS SOME MODEST QPF
INLAND OF THE LAKE BREEZES MONDAY AFTERNOON...BUT GIVEN THE LIMITED
BOUNDARY LAYER MOISTURE EXPECT AREAL COVERAGE TO BE QUITE SPARSE.
BASED ON THIS...WILL ONLY CARRY A SLIGHT CHANCE OF SHOWERS THROUGH
MONDAY...WITH THE BETTER CHANCE FOR SHOWERS LATER ON.
FURTHERMORE...THE GUSTY SOUTHWEST FLOW WILL PROBABLY SUPPRESS CLOUDS
NORTHEAST OF THE LAKES AND PROVIDE A FAIR AMOUNT OF SUNSHINE UNTIL
CLOUDS WITH THE SHORTWAVE MOVE IN LATE IN THE AFTERNOON. THIS SHOULD
ALLOW FOR EVEN WARMER TEMPERATURES IN MOST LOCATIONS ON MONDAY.
HIGHS SHOULD BE IN THE UPPER 70S TO LOWER 80S IN MOST AREAS...WITH
THE SOUTHWEST FLOW BRINGING THIS WARMTH RIGHT UP TO THE SOUTH SHORES
OF LAKE ONTARIO. NORTHEAST OF THE LAKES INCLUDING THE BUFFALO AND
WATERTOWN AREAS...THE FLOW OFF THE LAKE WILL RESULT IN COOLER
TEMPERATURES.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
A SURFACE COLD FRONT WILL SAG SLOWLY SOUTH THROUGH THE REGION DURING
MONDAY NIGHT. THE FRONT WILL BE ACCOMPANIED BY A FEW WEAK MID LEVEL
SHORTWAVES...ALTHOUGH THE STRONGER LARGE SCALE FORCING WILL REMAIN
WELL NORTH ACROSS QUEBEC. PRECIPITABLE WATER RISES TO AROUND 1.3
INCHES IN A NARROW CORRIDOR FOLLOWING THE FRONTAL ZONE. DESPITE THE
WEAK LARGE SCALE ASCENT...THE FRONT SHOULD HAVE ENOUGH LOW LEVEL
CONVERGENCE AND MOISTURE TO PRODUCE A HIGH LIKELIHOOD OF SHOWERS
OVERNIGHT. ENOUGH ELEVATED INSTABILITY WILL LINGER TO ALSO SUPPORT A
CHANCE OF A FEW WIDELY SCATTERED THUNDERSTORMS AS WELL. ANY
CONVECTION THAT DEVELOPS WILL BE WEAK GIVEN THE LIMITED INSTABILITY
AND MODEST SHEAR. EXPECT BASIN AVERAGE RAINFALL AMOUNTS OF A TENTH
TO A QUARTER INCH...WITH A FEW CORRIDORS OF HIGHER AMOUNTS WITH ANY
EMBEDDED CONVECTION.

THE COLD FRONT WILL PUSH SOUTH OF THE AREA EARLY TUESDAY...THEN HANG
UP ACROSS THE UPPER OHIO VALLEY AND PA TUESDAY AFTERNOON AND NIGHT.
THE CLOSER PROXIMITY OF THE STALLING FRONT WILL KEEP A CHANCE OF
SHOWERS GOING ACROSS THE SOUTHERN TIER TUESDAY AND TUESDAY EVENING.
FARTHER NORTH...A BUBBLE OF HIGH PRESSURE WILL BUILD INTO THE GREAT
LAKES AND SHOULD PROVIDE ENOUGH OF A LOW LEVEL DRY PUSH TO END THE
CHANCES OF RAIN FROM THE NYS THRUWAY NORTHWARD. PERIODS OF MID LEVEL
CLOUDS WILL CROSS WESTERN AND CENTRAL NY TUESDAY AND TUESDAY NIGHT
TO THE NORTH OF THE STALLED FRONTAL ZONE...WITH MORE SUNSHINE ACROSS
THE NORTH COUNTRY WHERE STRONGER SUBSIDENCE AND DRYING WILL BE FOUND.

A COOLER AIRMASS WILL BUILD INTO THE REGION TUESDAY...ALTHOUGH THE
COOLING WILL NOT EVEN DROP TEMPERATURES BACK QUITE TO AVERAGE.
EXPECT HIGHS IN THE MID 60S IN MOST LOCATIONS...WITH UPPER 60S
ACROSS THE NORTH COUNTRY WITH MORE SUNSHINE...AND ACROSS CENTRAL NY
TO THE FINGER LAKES. A NORTHERLY FLOW WILL KEEP THE LAKESHORES MUCH
COOLER.

THE AXIS OF SURFACE HIGH PRESSURE WILL CROSS THE REGION ON WEDNESDAY
WITH ABUNDANT SUNSHINE...DRY AIR AND LIGHT WINDS. TEMPERATURES WILL
CLIMB TO THE UPPER 60S TO LOWER 70S. THE CLEAR SKIES WILL LAST
THROUGH WEDNESDAY NIGHT AND A LIGHT DOWNSLOPING WIND ACROSS NEW YORK
STATE WEST OF THE FINGER LAKES WILL HOLD OVERNIGHT LOWS TO THE LOWER
50S...WITH MIDDLE 40S ACROSS CENTRAL AND NORTHERN NY.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
MEDIUM RANGE GUIDANCE IS IN VERY GOOD AGREEMENT WITH RESPECT TO THE
LARGE SCALE PATTERN. THE MAIN STORY WILL BE THE ONGOING WARMTH...
WITH TEMPERATURES RETURNING TO MID SUMMER-LIKE VALUES TOWARDS THE
END OF THE WEEK.

HIGH PRESSURE ON THURSDAY WILL DRIFT ACROSS NEW ENGLAND AND KEEP OUR
AREA DRY. WARMER AIR WILL BEGIN TO PUSH BACK INTO THE REGION AS
SOUTHERLY RETURN FLOW BEGINS AROUND THE DEPARTING HIGH. EXPECT HIGH
TEMPS TO REACH THE MID TO UPPER 70S AWAY FROM THE LAKES.

AN UPPER LEVEL RIDGE WILL BUILD INTO THE OHIO VALLEY AND EASTERN
GREAT LAKES FRIDAY AND SATURDAY WITH 850MB TEMPS SOARING INTO THE
+12C TO +14C RANGE. THIS WILL SUPPORT HIGHS IN THE LOWER 80S AWAY
FROM THE LAKES BOTH DAYS...WHICH WOULD BE THE NORMAL HIGH
TEMPERATURE AT THE HEIGHT OF SUMMER. POOR LAPSE RATES BENEATH THE
UPPER LEVEL RIDGE AND A LACK OF SYNOPTIC SCALE FORCING SHOULD KEEP
FRIDAY DRY...WITH SPURIOUS QPF ON BOTH THE GFS AND ECMWF HAVING THE
LOOK OF GRIDSCALE CONVECTIVE FEEDBACK. BY SATURDAY A WEAK COLD FRONT
WILL BEGIN TO SAG SOUTH THROUGH THE GREAT LAKES AND SOUTHERN ONTARIO
AND MAY PROVIDE ENOUGH CONVERGENCE TO SUPPORT A FEW SCATTERED
SHOWERS AND STORMS. GFS AND ECMWF HAVE MODERATE AGREEMENT THAT WILL
BE ON THE WARM SIDE OF THE THERMAL BOUNDARY AND THE THE FLAT RIDGE
ALOFT WILL HAVE ITS WESTERN FLANK IN THE MOIST FLOW OFF THE GULF OF
MEXICO. A WARM BUT WET WEEKEND IS EXPECTED.

LOOKING A LITTLE FARTHER AHEAD...THE VERY WARM TEMPERATURES WILL
LAST INTO EARLY THE FOLLOWING WEEK. RAIN AND THUNDERSTORM CHANCES
SHOULD INCREASE DURING THE 8-12 DAY RANGE AS A SERIES OF WEAK
SYSTEMS MOVE OUT OF THE UPPER MIDWEST AND THROUGH THE GREAT LAKES
STATES.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
VFR FLIGHT CONDITIONS WILL PREVAIL THE THRUOGH MAJORITY OF THE
06Z TAF CYCLE. INCREASING SOUTHWEST WINDS THIS AFTERNOON COULD
PRODUCE SOME GUSTS UP TO 30 KNOTS ACROSS THE NIAGARA FRONTIER TO
ROCHESTER...IMPACTING KIAG/KBUF/KROC. CIGS WILL LIKELY
DETERIORATE TO LOW-END VFR / MVFR AFTER 00Z AS RAIN SHOWERS AND
THUNDERSTORMS MOVE ACROSS THE AREA FROM WEST TO EAST ALONG A COLD
FRONT.

OUTLOOK...
MONDAY NIGHT AND TUESDAY...VFR/MVFR. SHOWERS LIKELY WITH A CHANCE
OF THUNDERSTORMS.
WEDNESDAY THROUGH FRIDAY...VFR.

&&

.MARINE...
SOUTHWEST WINDS WILL INCREASE SOME ON MONDAY AHEAD OF A
COLD FRONT...ALTHOUGH THE COLD LAKE WATERS WILL STABILIZE THE
BOUNDARY LAYER OVER THE LAKES AND KEEP WINDS LIGHTER IN THE MARINE
ENVIRONMENT THAN OVER THE SURROUNDING LAND. AT THIS TIME...IT
APPEARS WINDS WILL FALL JUST SHY OF SMALL CRAFT CRITERIA. WINDS WILL
DIMINISH BEHIND THE FRONT...WITH QUIET CONDITIONS EXPECTED MID-WEEK
AS HIGH PRESSURE NOSES TOWARD THE WATERS.

&&

.FIRE WEATHER...
WINDS WILL BE STRONGER ON MONDAY THAN SUNDAY IN ADVANCE OF A COLD
FRONT WHICH IS APPROACHING THE REGION. WIND GUSTS OF 25 MPH TO 35
MPH ARE LIKELY WITH THE STRONGEST WINDS NORTHEAST OF THE EASTERN
GREAT LAKES. HUMIDITY IS THE KEY FACTOR FOR THE FIRE WEATHER
WATCH. TYPICALLY MODEL GUIDANCE CAN BE TOO MOIST WITH SURFACE DEW
POINTS...SO THE FORECAST REFLECTS SURFACE- 925MB MIXED HUMIDITY`S
FROM THE NAM/RGEM MODEL GUIDANCE. EVEN WITH THESE LOWER DEW
POINTS...HUMIDITIES ARE MARGINAL FOR RED FLAG CRITERIA. HUMIDITY
SHOULD REMAIN ABOVE 30 PERCENT IN THE LAKE BREEZE WHERE THE LAKE
SHOULD MODIFY THE AIR JUST AS IT DID TODAY. THE GREATEST POTENTIAL
FOR RED FLAG CRITERIA IS INLAND WHERE HUMIDITY WILL BE DRIER AND
TEMPERATURES WILL BE WARMER. CONSIDERING BOTH OF THESE FACTORS WE
HAVE ISSUED A FIRE WEATHER WATCH FOR THE FINGER LAKES REGION AND
IN THE LOWER GENESEE VALLEY. A COLUMN OF COUNTIES WEST OF THE FIRE
WEATHER WATCH...CONDITIONS MAY ALSO REACH RED FLAG CRITERIA.
CONFIDENCE IS TOO LOW AT THIS POINT IN TIME TO EXPAND THE FIRE
WEATHER WATCH AS LAKE MOISTURE BEHIND THE LAKE BREEZE BOUNDARY MAY
REACH MUCH OF THESE AREAS TOMORROW. FOR NOW WE WILL HAVE TO
MONITOR ORLEANS COUNTY DOWN TO ALLEGANY COUNTY FOR FIRE WEATHER
CONCERNS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...FIRE WEATHER WATCH FROM NOON EDT TODAY THROUGH THIS EVENING
     FOR NYZ003>005-013-014.
MARINE...NONE.

&&

$$

SYNOPSIS...APFFEL
NEAR TERM...APFFEL/THOMAS
SHORT TERM...HITCHCOCK/WCH
LONG TERM...HITCHCOCK/WCH
AVIATION...CHURCH
MARINE...APFFEL/WCH
FIRE WEATHER...APFFEL/THOMAS


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