Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 050228
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1028 PM EDT TUE AUG 4 2015

.SYNOPSIS...
A SECONDARY COLD FRONT WILL CROSS THE AREA THIS EVENING WITH
SCATTERED SHOWERS AND A FEW THUNDERSTORMS. FOLLOWING THE PASSAGE OF
THIS SECOND COLD FRONT...A FEW SCATTERED SHOWERS WILL LINGER ACROSS
THE NORTH COUNTRY THROUGH WEDNESDAY. OTHERWISE IT WILL TURN DRIER
AND COOLER FOR THE REMAINDER OF THE WEEK.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
RADAR IMAGERY LATE THIS EVENING SHOWING A BROKEN LINE OF CONVECTION
PUSHING ESE ACROSS THE WESTERN SOUTHERN TIER AND TOWARDS THE WESTERN
FINGER LAKES. ANOTHER AREA OF WEAKENING SHOWERS IS PUSHING ACROSS
THE EASTERN LAKE ONTARIO REGION. THESE ARE BEING SUPPORTED BY A PRE-
FRONTAL TROUGH AND A WEAK MID LEVEL SHORTWAVE WITH THEIR ASSOCIATED
LARGE SCALE ASCENT AND LOW LEVEL CONVERGENCE. THE SHOWERS AND
ISOLATED THUNDERSTORMS WILL CONTINUE TO PUSH EAST AND WEAKEN THROUGH
THE MIDNIGHT HOUR. THE WEAK SECONDARY COLD FRONT IS STILL UPSTREAM
ACROSS SOUTHERN ONTARIO...AND THIS WILL PASS THROUGH THE REGION
OVERNIGHT AND POSSIBLY PRODUCE A FEW MORE ISOLATED SHOWERS.

ONCE THE SECONDARY FRONT PASSES...THIS WILL OVERALL RESULT IN
REDUCTION OF SHOWER AND THUNDERSTORM ACTIVITY OVERNIGHT... AS DRIER
AIR AND SOME SUBSIDENCE WORK INTO THE AREA BEHIND THE BOUNDARY. THE
EXCEPTION IS THE EASTERN LAKE ONTARIO REGION WHERE LAKE SURFACE
TEMPS TO 850MB TEMP DIFFERENCE NEARS 13 DEGREES C WHICH SHOULD BE
ENOUGH...WITH VERY UNSTABLE LAPSE RATES REMAINING IN PLACE IN THE
MID-LEVELS...TO PROMOTE SOME LAKE ENHANCEMENT TO THE SHOWERS AND
THUNDERSTORMS LATE TONIGHT BEHIND THE COLD FRONT. A FEW LAKE
ENHANCED SHOWERS ARE ALSO POSSIBLE EAST OF LAKE ONTARIO LATE TONIGHT
AND EARLY WEDNESDAY MAINLY ACROSS CHAUTAUQUA AND SOUTHERN ERIE
COUNTIES.

ON WEDNESDAY... TEMPERATURES WILL RUN ABOUT 10 DEGREES F BELOW
NORMAL AS THE UPPER LEVEL LOW REMAINS OVERHEAD. THE CORE OF GREATEST
INSTABILITY ALOFT WILL REMAIN OVER THE NORTH COUNTRY AND ADIRONDACKS
DURING THE DAY ON WEDNESDAY. PURE LAKE EFFECT WOULD NORMALLY FIZZLE
OUT INTO THE DAY ON WEDNESDAY WITH A LOSS OF CONVERGENCE OVER THE
LAKE HOWEVER... THE NORTH COUNTRY WILL SEE A MODE CHANGE FROM LAKE
ENHANCED SHOWERS AND THUNDERSTORMS TO JUST DIURNALLY UNSTABLE
SHOWERS AND THUNDERSTORMS IN THE UNSTABLE NORTHWESTERLY FLOW AND
OROGRAPHIC ENHANCEMENT. OTHERWISE... ALL OF WESTERN NEW YORK SHOULD
SEE A MOSTLY DRY DAY AND PLEASANT DAY ON WEDNESDAY.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
NO CHANGES TO THE FORECAST THIS EVENING...PREVIOUS DISCUSSION
FOLLOWS.

THE UPPER LEVEL TROUGH THAT HAS BEEN BRINGING THE COOLER AND
UNSETTLED WEATHER TO THE REGION WILL BE IN THE PROCESS OF DEPARTING
THE REGION AS WE MOVE THROUGH WEDNESDAY NIGHT AND INTO THURSDAY
MORNING. A FEW SHOWERS WILL BE DIMINISHING DURING THE EVENING HOURS
ACROSS THE NORTH COUNTRY OWING TO THE COMBINATION OF DIURNAL
INSTABILITY...COLD AIR ALOFT...AND AREAS OF VORTICITY ROTATING
AROUND THE LOW CENTERED OVER QUEBEC. PERSISTENT ONSHORE/UPSLOPE FLOW
WITH NOMINAL LAKE ENHANCEMENT WILL KEEP A LOW CHANCE OF A SHOWER
POPPING UP SOUTHEAST OF LAKE ONTARIO OVERNIGHT...THOUGH THE
INCREASINGLY DRY AIR ALOFT WILL SEVERELY LIMIT ANY NASCENT ACTIVITY.

ELSEWHERE...LOOK FOR DRY CONDITIONS TO PERSIST THROUGH THE END OF
THE WORK WEEK AS THE DEPARTING TROUGH GIVES WAY TO MORE ZONAL FLOW
ALOFT WITH HIGH PRESSURE AT THE SURFACE WITH ONLY SOME DIURNAL CU
INLAND TO CONTEND WITH IN THE AFTERNOON ON THURSDAY...GIVING WAY TO
PARTLY CLOUDY SKIES THURSDAY NIGHT AS THE HIGH MOVES OVERHEAD.
MID/HIGH CLOUD COVER MAY BE A LITTLE MORE WIDESPREAD NEAR THE PA
BORDER THURSDAY NIGHT...CLOSER TO A LOW PRESSURE SYSTEM THAT WILL BE
SLIDING BY WELL TO OUR SOUTH ACROSS THE OHIO VALLEY AND CENTRAL
APPALACHIANS. OTHERWISE...FRIDAY AND FRIDAY NIGHT SHOULD SEE MUCH OF
THE SAME AS WEAK SURFACE HIGH PRESSURE REMAINS OVER THE LOWER GREAT
LAKES.

REGARDING TEMPERATURES...WEDNESDAY NIGHT WILL BE THE COOLEST NIGHT
OF THE PERIOD AS THE EFFECTS OF THE DEPARTING UPPER LEVEL LOW WILL
BE MOST KEENLY FELT. LOWS WILL RUN IN THE 50S WITH A FEW SHELTERED
SPOTS IN THE SOUTHERN TIER POTENTIALLY DIPPING INTO THE UPPER 40S.
THE COOL AIR ALOFT WILL ONLY SLOWLY MODIFY THROUGH THE REST OF THE
PERIOD OWING TO WEAK TEMPERATURE ADVECTION WITH HIGHS THURSDAY AND
FRIDAY RUNNING JUST A COUPLE OF DEGREES BELOW AVERAGE WITH READINGS
GENERALLY IN THE MID TO UPPER 70S AND LOWS IN THE 50S.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
THE WEEKEND WILL FEATURE A RETURN TO MORE UNSETTLED WEATHER AS
SEVERAL UPPER LEVEL VORTICITY MAXIMA STRADDLING THE U.S. CANADIAN
BORDER OVER THE NORTHERN PLAINS WILL DROP ACROSS THE GREAT LAKES.
WHILE A LACK OF DEEP MOISTURE AND LACK OF ORGANIZATION SHOULD
PREVENT THE WEEKEND FROM BEING A COMPLETE WASHOUT...THE SYSTEMS WILL
AT LEAST PRESENT OPPORTUNITY FOR THE DEVELOPMENT OF SCATTERED
SHOWERS AND THUNDERSTORMS...PARTICULARLY ON SUNDAY INTO MONDAY AS
THE LONGWAVE TROUGH BECOMES RE-ESTABLISHED ACROSS THE REGION.
TEMPERATURES WILL REMAIN WITHIN A COUPLE OF DEGREES OF NORMAL WITH
HIGHS IN THE MID TO UPPER 70S AND LOWS IN THE MID 50S INLAND TO THE
LOWER 60S NEAR THE LAKES.

&&

.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
A SECONDARY COLD FRONT AND WEAK MID LEVEL TROUGH WILL CROSS THE
REGION THIS EVENING AND SUPPORT SCATTERED SHOWERS AND A FEW
THUNDERSTORMS EAST OF LAKE ONTARIO AND ACROSS THE SOUTHERN TIER AND
WESTERN FINGER LAKES. VFR WILL PREVAIL...BUT ANY OF THE HEAVIER
SHOWERS WILL CONTAIN VERY BRIEF MVFR/IFR CONDITIONS.

OVERNIGHT THE COLD FRONT WILL PUSH EAST OF THE AREA WITH MOST OF THE
SHOWERS ENDING FROM WEST TO EAST. THE FRONT WILL USHER IN A COOLER
AIRMASS...AND MAY ACTUALLY BE COOL ENOUGH TO SUPPORT A FEW LAKE
ENHANCED SHOWERS EAST OF LAKES ERIE AND ONTARIO LATE TONIGHT AND
WEDNESDAY MORNING. MOST OF THIS SHOULD AVOID THE TAF SITES. LATER
WEDNESDAY COOL AIR ALOFT AND ANOTHER MID LEVEL TROUGH WILL SUPPORT
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS EAST OF LAKE ONTARIO
INCLUDING KART. A FEW OF THESE SHOWERS MAY BRIEFLY DROP CIGS/VSBY TO
MVFR...BUT VFR SHOULD PREVAIL ON WEDNESDAY WITH AREAS OF CUMULUS AND
STRATOCUMULUS FORMING IN THE COOL AIR ALOFT.


OUTLOOK...
THURSDAY THROUGH SUNDAY...VFR.

&&

.MARINE...
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS
THE LAKES THIS EVENING...WITH THE POTENTIAL FOR GUSTY WINDS AND
SMALL HAIL. GIVEN THE WARM LAKE TEMPERATURES AND COLD AIR MASS
ALOFT...CANNOT RULE OUT THE CHANCE FOR SOME WATERSPOUTS TONIGHT INTO
EARLY WEDNESDAY ON LAKES ERIE AND ONTARIO. WATERSPOUTS FORM MAINLY
IN AND NEAR SHOWERS AND AREAS OF TOWERING CUMULUS WHERE LOW LEVEL
CONVERGENCE IS MAXIMIZED.

SMALL CRAFT CONDITIONS WILL PERSIST ON LAKE ERIE INTO THIS
EVENING AS A STIFF SOUTHWESTERLY FLOW REMAINS IN PLACE AHEAD OF A
SURFACE COLD FRONT. WINDS WILL TURN MORE NORTHWESTERLY AND WEAKEN
THROUGH THE OVERNIGHT...ALLOWING CONDITIONS TO IMPROVE SOMEWHAT ON
LAKE ERIE.

ON LAKE ONTARIO...STRONGER NORTHEASTERLY WINDS WILL PICK ON ON
WEDNESDAY BEHIND THE SURFACE COLD FRONT...AND WILL EXCEED SMALL
CRAFT CONDITIONS. THUS HAVE ISSUED A SMALL CRAFT ADVISORY FOR MUCH
OF CENTRAL AND EASTERN PORTIONS OF LAKE ONTARIO FROM LATE WEDNESDAY
MORNING THROUGH WEDNESDAY EVENING.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM WEDNESDAY TO MIDNIGHT EDT
         WEDNESDAY NIGHT FOR LOZ043>045.

&&

$$

SYNOPSIS...CHURCH/HITCHCOCK
NEAR TERM...CHURCH/HITCHCOCK
SHORT TERM...SMITH/WOOD
LONG TERM...WOOD
AVIATION...HITCHCOCK
MARINE...CHURCH



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