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000
FXUS61 KBUF 221808
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
208 PM EDT WED MAY 22 2013

.SYNOPSIS...
A WARM AND HUMID AIRMASS WILL REMAIN IN PLACE THROUGH TONIGHT WITH
SHOWERS AND THUNDERSTORMS FORMING. IT WILL TURN COOLER
TOMORROW...AND SHOWERS WILL BECOME MORE WIDESPREAD AS A COLD FRONT
PASSES THROUGH. A FEW OF THESE SHOWERS MAY LINGER INTO EARLY
FRIDAY...BEFORE DRIER AIR SETTLES INTO THE REGION FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
THIS AFTERNOON SEVERAL CLUSTERS OF SHOWERS AND THUNDERSTORMS HAVE
BLOSSOMED JUST TO OUR EAST...BUT OVER OUR REGION MAINLY CLEAR SKIES
PREVAIL. THIS HAS ALLOWED FOR TEMPERATURES TO RISE A FEW DEGREES
WARMER...AND ALSO INCREASED THE AMOUNT OF INSTABILITY.

VISIBLE SATELLITE IMAGERY SHOWS A LAKE BREEZE OFF LAKE ERIE AND WITH
THIS SOUTHWEST FLOW AREAS ALONG THE IMMEDIATE LAKE SHORE AND THE
BUFFALO METRO AREA WILL LIKELY REMAIN DRY THROUGH THE AFTERNOON
HOURS.

INLAND SOME CU HAS BLOSSOMED THIS AFTERNOON ACROSS WNY AND THE NORTH
COUNTRY. WITH THE ADDITIONAL DAYTIME INSTABILITY WE ARE STILL
EXPECTING SHOWERS AND THUNDERSTORMS TO BLOSSOM THIS AFTERNOON. THE
GREATEST INSTABILITY WITH LI`S OF -7C AND SBCAPE OF 2500+ J/KG IS
OVER INTERIOR WNY. THE CU OVER WNY FORMING WITHIN THIS AREA OF
GREATEST INSTABILITY WILL LIKELY FORM SHOWERS AND THUNDERSTORMS OVER
THE FINGER LAKES REGION AND LATER THE EASTERN LAKE ONTARIO REGION.
WILL HIGHLIGHT THE HIGHEST POPS TODAY AND THIS EVENING WITHIN THIS
REGION. CONVECTION ACTIVITY WILL CONTINUE THROUGH THE EVENING HOURS
WHEN ADDITIONAL CONVERGENT LIFT AHEAD OF A 45 KNOT LLJ AND MOISTURE
ADVECTION FUELS SHOWERS AND THUNDERSTORMS.

FOR TONIGHT LOW LEVEL MOISTURE CARRIES NORTHWARD AND THROUGH THE
LATE EVENING AND OVERNIGHT EXPECT SHOWERS TO DIMINISH...ESPECIALLY
SOUTH OF LAKE ONTARIO. LOWS TONIGHT WILL REMAIN IN THE 60S.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
AFTER A STRETCH OF MID SUMMER WARMTH AND HUMIDITY...A SUBTLE CHANGE
IN THE OVERALL PATTERN WILL YIELD A NOTICEABLY COOLER AND MORE
COMFORTABLE WEATHER REGIME. RATHER THAN EXPERIENCING TEMPERATURES
MORE TYPICAL OF JULY...WE CAN LOOK FORWARD TO MERCURY LEVELS THAT
WILL AVERAGE SOME 5 TO 10 DEG BELOW NORMAL. THIS WILL ALL COME AS A
RESULT OF THE EXITING OF A SULTRY RIDGE OFF THE EAST COAST...WHICH
WILL BE REPLACED BY AN EXCEPTIONALLY HIGH AMPLITUDE FLOW OVER ALL OF
NORTH AMERICA. THE PSEUDO-OMEGA BLOCK PATTERN WILL FEATURE A RIDGE
OVER THE NATIONS MID SECTION WITH TWIN TROUGHS OVER BRITISH COLUMBIA
AND QUEBEC. THE DETAILS...

A BROAD...COMPLEX AREA OF LOW PRESSURE EXTENDING FROM THE SAINT
LAWRENCE VALLEY ACROSS THE LOWER GREAT LAKES ON THURSDAY MORNING
WILL SLOWLY PIVOT TO THE EAST COAST BY DAYBREAK FRIDAY. THE LIFT
PROVIDED BY 100M HGT FALLS AND LOW LEVEL CONVERGENCE WITHIN THE AXIS
OF ELONGATED SFC TROUGH WILL LEAD TO FAIRLY WIDESPREAD LIGHT RAIN
DURING THE DAY...THEN A TRAILING DEFORMATION ZONE ON THE WEST SIDE
OF THE EXITING SFC TROUGH WILL KEEP THE RAIN INTACT FOR THURSDAY
NIGHT. WILL COVER BOTH PERIODS WITH CAT POPS...BUT QPF IS NOT
EXPECTED TO BE SIGNIFICANT. RAINFALL AMOUNTS FOR THE 24 HOUR PERIOD
SHOULD AVERAGE A QUARTER TO A HALF INCH.

AS MENTIONED EARLIER...IT WILL BE MUCH COOLER ON THURSDAY. H85 TEMPS
THAT UP TO THIS POINT HAD BEEN IN THE MID TEENS WILL TUMBLE INTO THE
SINGLE DIGITS BY THURSDAY EVENING...THEN TO NEAR ZERO BY DAYBREAK
FRIDAY. THIS WILL TRANSLATE INTO MIDDAY HIGHS OF 70 TO 75 BEFORE
TEMPERATURES STEADILY FALL IN THE RAIN DURING THE AFTERNOON THROUGH
THURSDAY NIGHT. MERCURY READINGS BY DAYBREAK FRIDAY COULD BE 20
DEGREES LOWER IN MANY AREAS THAN THE NIGHT BEFORE....WITH OVERNIGHT
LOWS GENERALLY IN THE MID TO UPPER 40S.

ON FRIDAY...THE BACK EDGE TO THE SOAKING RAIN WILL BE FOUND PUSHING
EAST FROM THE GENESEE VALLEY AS THE SUPPORTING H5 TROUGH WILL BE
CROSSING OVERHEAD. DURING THE COURSE OF THE DAY...THE AFOREMENTIONED
DEFORMATION ZONE WILL GIVE WAY TO MUCH DRIER AIR FROM SOUTHERN
ONTARIO...WITH THE LEFTOVER SHOWERS AND ASSOCIATED LOW CLOUD COVER
GIVING WAY TO INCREASING AMOUNTS OF SUN FROM WEST TO EAST. THIS WILL
LEAVE PARTLY TO MOSTLY SKIES FOR THE AFTERNOON...ALTHOUGH THERE WILL
BE A FEEL OF AUTUMN IN THE AIR AS H85 TEMPS NEAR ZERO C WILL
CORRESPOND TO NEAR SFC TEMPS IN THE 50S F.

IT WILL THEN BECOME DOWNRIGHT CHILLY (IF NOT COLD) ACROSS THE
FORECAST AREA FRIDAY NIGHT. WHILE A ROBUST SHORTWAVE WILL DROP
ACROSS THE LOWER GREAT LAKES...A VERY DRY AIRMASS SHOULD STILL
ENCOURAGE CLEAR TO PARTLY CLOUDY SKIES. TEMPS WILL BE MARGINALLY
COLD ENOUGH FOR SOME LAKE INDUCED CLOUD COVER...BUT THE AMOUNT OF
DRY SYNOPTIC AIR AND PRESENCE OF A STRONG LOW LEVEL INVERSION SHOULD
WORK AGAINST THIS POTENTIAL. TEMPS SHOULD THUS FALL TO NEAR 40
ACROSS THE LAKE PLAINS WITH READINGS IN THE MID TO UPPER 30S ACROSS
THE SRN TIER AND EASTERN LK ONTARIO REGION. THIS WILL LEND TO THE
RISK FOR SOME FROST...SO WILL HAVE TO KEEP THIS IN THE BACK OF OUR
MINDS.

A LARGE SFC HIGH CENTERED NEAR JAMES BAY WILL NOSE SOUTH ACROSS THE
GREAT LAKES SATURDAY AND SATURDAY NIGHT. WHILE SOME OF THE GUIDANCE
PACKAGES ARE SUGGESTING THE PASSAGE OF A COUPLE OF MID LEVEL
SHORTWAVES...THE MOISTURE STARVED AIRMASS IS NOT EXPECTED TO SUPPORT
ANY SHOWERS. RATHER...CLEAR TO PARTLY CLOUDY SKIES ARE ANTICIPATED
WITH BELOW NORMAL TEMPERATURES. HIGHS ON SATURDAY SHOULD BE WITHIN A
COUPLE DEGREES OF 60 WHILE SATURDAY NIGHT WILL HAVE THE POTENTIAL TO
PRODUCE ANOTHER FROSTY NIGHT AWAY FROM THE LAKES.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
SEASONABLY COOL AND DRY WEATHER WILL PREVAIL THROUGH THE REMAINDER
OF THE HOLIDAY WEEKEND...COURTESY OF HIGH PRESSURE THAT WILL BE
PARKED ACROSS THE GREAT LAKES. IT WILL BE QUITE CHILLY BOTH SATURDAY
AND SUNDAY NIGHTS WITH TEMPERATURES DROPPING INTO THE LOW 40S ACROSS
THE LAKE PLAINS WHILE 30S WILL DOMINATE THE COLDER SPOTS OF THE
SOUTHERN TIER AND NORTH COUNTRY. THIS WILL KEEP THE THREAT OF FROST
IN PLACE FOR THOSE COLDER AREAS
.
DAYTIME HIGHS WILL GRADUALLY INCREASE DURING THE PERIOD AS THE
STRONG RIDGE OVER THE CENTRAL U.S. WILL NUDGE EASTWARD. HIGHS OF 60
TO 65 ON SUNDAY WILL MAKE THEIR WAY TO ABOVE NORMAL LEVELS (MID 70S)
BY TUESDAY AFTERNOON.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
AT 18Z VFR FLIGHT CONDITIONS WERE FOUND ACROSS THE REGION WITH A FEW
SHOWERS AND THUNDERSTORMS STARTING TO BLOSSOM ACROSS THE LOWER
GENESEE VALLEY. WILL CARRY THUNDERSTORMS ACROSS THE EASTERN LAKE
ONTARIO REGION...INCLUDING THE KART TAF FOR THIS LATE EVENING AND
EARLY OVERNIGHT...WITH OTHER LOCATIONS JUST CARRY A VICINITY
THUNDERSTORM. SOME BRIEF MVFR VSBYS ARE POSSIBLE WITHIN ANY STORM.

FOR TONIGHT SHOWERS AND THUNDERSTORMS WILL CARRY NORTHWARD...WITH A
LLJ OF 35 TO 40 KNOTS ACROSS THE REGION. WILL CARRY LLWS OVERNIGHT
IN THE TAFS.

TOMORROW MORNING HOURS WILL LIKELY BE DRY AND OVERCAST WITH SHOWERS
BECOMING MORE LIKELY LATER IN MORNING AND EARLY AFTERNOON AS A COLD
FRONT NEARS THE REGION. AT THIS TIME THUNDER LOOKS TO BE LIMITED
ALONG THE COLD FRONT.

OUTLOOK...
THURSDAY AFTERNOON...SCATTERED TO NUMEROUS SHOWERS AND POSSIBLY A
THUNDERSTORM WITH ASSOCIATED MVFR/IFR...OTHERWISE VFR.
THURSDAY NIGHT IFR/MVFR IN SHOWERS.
FRIDAY...MAINLY VFR WITH A CHANCE OF SHOWERS.
SATURDAY THROUGH MONDAY...VFR.

&&

.MARINE...
RELATIVELY LIGHT AND VARIABLE WINDS WILL PREVAIL THROUGH EARLY THIS
MORNING. SOUTHWEST WINDS WILL PICK UP A BIT THIS AFTERNOON AND
TONIGHT AS AN AREA OF LOW PRESSURE AND ITS TRAILING COLD FRONT
APPROACH WESTERN NEW YORK. AFTER THE FRONT CROSSES WESTERN AND
CENTRAL NEW YORK ON THURSDAY...THE WINDS WILL VEER TO THE NORTHWEST.
SMALL CRAFT ADVISORIES MAY BE NEEDED THURSDAY NIGHT INTO FRIDAY
AS NORTH TO NORTHWEST WINDS PICK UP BEHIND THE DEPARTING FRONT.

&&

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

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...THOMAS
SHORT TERM...RSH
LONG TERM...RSH/WOOD
AVIATION...THOMAS
MARINE...TJP