Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 010820
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
420 AM EDT SAT AUG 1 2015

.SYNOPSIS...
HIGH PRESSURE OVER THE OHIO VALLEY THIS MORNING WILL EXTEND NORTH
TO THE LOWER GREAT LAKES THIS AFTERNOON. WHILE THIS WILL PROVIDE
THE BULK OF OUR REGION WITH FAIR DRY WEATHER THROUGH THE
WEEKEND...A ROBUST MID LEVEL DISTURBANCE COULD TOUCH OFF A SHOWER
OR THUNDERSTORM THIS AFTERNOON OR EVENING. A COLD FRONT WILL THEN
BRING A HIGHER CHANCE FOR SHOWERS AND STORMS TO THE REGION SUNDAY
NIGHT AND MONDAY. THIS FRONT WILL USHER IN A MUCH COOLER AIRMASS
FOR MUCH OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
A FAIRLY ROBUST MID LEVEL DISTURBANCE TRACKING EAST ACROSS LAKE
ONTARIO (AS OF THE WRITING OF THIS DISCUSSION) PUSHED A COOL
FRONTAL BOUNDARY ACROSS OUR FORECAST AREA OVERNIGHT. THIS RESULTED
IN A FEW SHOWERS AND THUNDERSTORMS...PARTICULARLY OVER THE EASTERN
LAKE ONTARIO REGION WHERE THE CONVECTION INTENSIFIED TO SEVERE
LEVELS. THIS ACTIVITY HAS SINCE WEAKENED AND IS NOW IN THE PROCESS
OF PUSHING EAST ACROSS THE ADIRONDACKS.

AS FOR TODAY...HIGH PRESSURE CENTERED OVER THE OHIO VALLEY WILL
NOSE NORTHWARDS TO THE LOWER GREAT LAKES. THIS WILL PROVIDE THE
BULK OF OUR REGION WITH FAIR DRY WEATHER...ALTHOUGH ANOTHER
IMPULSE OF ENERGY IN THE MID LEVELS WILL HAVE TO BE WATCHED FOR
THIS AFTERNOON AND EVENING. AS OF 08Z...THE SHORTWAVE COULD BE
SEEN IN WV IMAGERY DIGGING ITS WAY SOUTHEASTWARD ACROSS LAKE
SUPERIOR. IT WILL CROSS LAKE ONTARIO LATER THIS AFTERNOON AND
EARLY EVENING...JUST AS OUR AIRMASS REACHES ITS GREATEST DIURNAL
INSTABILITY. SBCAPES WILL APPROACH 1000 J/KG AT THE TIME OF ITS
PASSAGE...BUT WITH A RELATIVELY DRY AIRMASS IN PLACE AND A STRONG
LAKE BREEZE EXTENDING NORTHEAST FROM LAKE ERIE...THE CONVECTION IS
NOT EXPECTED TO BE WIDESPREAD. THE GREATEST CHANCE FOR ANY
THUNDERSTORM ACTIVITY WILL BE FOUND WELL INLAND FROM LAKE ERIE AND
ITS SHADOW...PLACING THE FOCUS FROM ABOUT GENESEE COUNTY TO THE
FINGER LAKES REGION. ALL IN ALL THOUGH...THE DAY WILL BE LARGELY
RAIN FREE.

TEMPERATURES TODAY WILL BE A FEW DEGREES LOWER THAN THOSE FROM
FRIDAY...AS H85 TEMPS AVERAGING 12C WILL ONLY ENCOURAGE THE
MERCURY TO CLIMB INTO THE UPPER 70S TO NEAR 80 IN MOST LOCATIONS.

TONIGHT...ANY LATE AFTERNOON CONVECTION WILL QUICKLY DIE OFF
EARLY IN THE EVENING...LEAVING SUBSIDENCE FROM THE AFOREMENTIONED
SFC HIGH AS THE DOMINATING WEATHER FEATURE. TEMPERATURES TONIGHT
WILL DROP INTO THE LOWER 60S ACROSS THE LAKE PLAINS WHILE MINS
WILL BE FOUND IN THE MID 50S IN THE COOLER SRN TIER VALLEYS AND
POSSIBLY THE FOOTHILLS OF THE ADIRONDACKS.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
ON SUNDAY SURFACE HIGH PRESSURE WILL REMAIN ANCHORED FROM THE
CENTRAL APPALACHIANS TO NEW ENGLAND...WHILE UPSTREAM THE NEXT
SIGNIFICANT SHORTWAVE TROUGH WILL DIG ACROSS THE UPPER GREAT
LAKES...ALONG WITH ITS ATTENDANT COLD FRONT. WITH THE 00Z GUIDANCE
SUITE HAVING UNIVERSALLY SLOWED THE TIMING OF THIS NEXT
SYSTEM...IT NOW APPEARS THAT SUNDAY SHOULD REMAIN MOSTLY IF NOT
ENTIRELY DRY...WITH JUST SOME LOW-END CHANCES OF A
SHOWER/THUNDERSTORM REACHING THE SAINT LAWRENCE VALLEY AND EXTREME
FAR WESTERN NEW YORK BY VERY LATE SUNDAY AFTERNOON/EARLY SUNDAY
EVENING. WITH THE WARM ADVECTION REGIME OUT AHEAD OF THE
APPROACHING SHORTWAVE HELPING TO PUSH 850 MB TEMPS INTO THE +13C
TO +16C RANGE AND A TIGHTENING PRESSURE GRADIENT PROMOTING AN
INCREASING SOUTHWESTERLY BREEZE/CONSEQUENT GOOD MIXING...AFTERNOON
HIGH TEMPERATURES SHOULD MOSTLY RANGE IN THE LOWER TO MID 80S.

DURING THE COURSE OF SUNDAY NIGHT AND MONDAY...THE AFOREMENTIONED
SHORTWAVE TROUGH WILL DIG FURTHER SOUTHEASTWARD INTO THE LOWER
GREAT LAKES...WHILE AT THE SURFACE A PRE-COLD FRONTAL TROUGH WILL
EASE INTO THE REGION SUNDAY NIGHT...FOLLOWED BY THE TRAILING COLD
FRONTAL BOUNDARY ON MONDAY. WHILE THE MAIN OPERATIONAL MODELS
CONTINUE TO EXHIBIT SOME MODEST TIMING DIFFERENCES...IN GENERAL
THE INCREASING MOISTURE AND LARGE-SCALE LIFT ATTENDANT TO THESE
FEATURES WILL BRING AN INCREASED RISK FOR SHOWERS AND
THUNDERSTORMS DURING THIS PERIOD. AT THIS JUNCTURE THE GREATEST
CONVECTIVE POTENTIAL/COVERAGE APPEARS AS IF IT WILL LIKELY FOCUS
ON THE OVERNIGHT SUNDAY NIGHT AND MONDAY TIME FRAME...DURING WHICH
THE LOW LIKELY POPS FROM OUR EXISTING CONTINUITY LOOKED VERY
REASONABLE AND HAVE THUS BEEN MAINTAINED.

WITH RESPECT TO SEVERE POTENTIAL...INSTABILITY LEVELS SHOULD
INITIALLY BE HELD IN CHECK BY THE UNFAVORABLE PORTION OF THE
DIURNAL CYCLE LATER SUNDAY NIGHT THROUGH THE FIRST PART OF MONDAY
MORNING...WHICH SHOULD HELP TO GREATLY LIMIT THE POTENTIAL FOR
STRONGER STORMS THROUGH THAT TIME. THIS COULD HOWEVER CHANGE BY
LATER MONDAY MORNING/AFTERNOON AS RENEWED DIURNAL HEATING MAY LEAD
TO INCREASING INSTABILITY OUT AHEAD OF THE APPROACHING COLD
FRONT...WITH THE EXACT AMOUNT OF DESTABILIZATION WE CAN EXPECT
REMAINING UNCERTAIN AT THIS POINT AND HIGHLY DEPENDENT ON BOTH THE
TIMING OF THE FRONT AND THE AMOUNT OF ANY CLOUD COVER/PRECIP
INITIALLY PRESENT MONDAY MORNING. SHOULD SUFFICIENT
DESTABILIZATION BE REALIZED...ENOUGH DEEP-LAYER SHEAR LOOKS TO BE
IN PLACE TO SUPPORT AT LEAST A LOW CHANCE FOR SOME STRONGER TO
MARGINALLY SEVERE STORMS. IN THEIR NEW DAY 3 CONVECTIVE
OUTLOOK...SPC HAS PLACED MUCH OF OUR REGION IN A MARGINAL RISK FOR
SEVERE STORMS ON MONDAY...AND THIS LOOKS QUITE REASONABLE GIVEN
THE ABOVE FACTORS.

FOLLOWING THE PASSAGE OF THE COLD FRONT...SUBSIDENCE IN ITS WAKE
ALONG WITH THE ARRIVAL OF A SWATH OF SOMEWHAT DRIER AIR SHOULD
LEAD TO PRECIP CHANCES DIMINISHING FROM WEST TO EAST LATER MONDAY
AFTERNOON AND EVENING... WITH MAINLY DRY WEATHER THEN FOLLOWING
FOR THE SECOND HALF OF MONDAY NIGHT.

WITH REGARD TO TEMPERATURES FROM SUNDAY NIGHT ONWARD...LOWS
SUNDAY NIGHT SHOULD RANGE SOLIDLY ABOVE NORMAL OUT AHEAD OF THE
APPROACHING COLD FRONT...WITH READINGS RANGING FROM THE LOWER 60S
ACROSS INTERIOR PORTIONS OF THE SOUTHERN TIER/NORTH COUNTRY TO
NEAR 70 ALONG THE LAKESHORES. AFTER THAT...EXPECT READINGS TO
RETURN TO NEAR NORMAL LEVELS FOR THE BALANCE OF THE PERIOD...WITH
DAYTIME HIGHS AVERAGING OUT NEAR 80 ON MONDAY...AND NIGHTTIME LOWS
THEN DROPPING BACK INTO THE UPPER 50S TO LOWER 60S MONDAY NIGHT.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
IN THE BIG PICTURE...THE EXTENDED PORTION OF THE FORECAST WILL
FEATURE UPPER LEVEL TROUGHING DIGGING ACROSS THE GREAT LAKES AND
NORTHEAST THROUGH MIDWEEK...BEFORE GRADUALLY LIFTING OUT INTO THE
CANADIAN MARITIMES THURSDAY AND FRIDAY AND ALLOWING THE LARGE-
SCALE FLOW ACROSS OUR REGION TO TREND MORE QUASI-ZONAL AGAIN BY
THE END OF THE PERIOD. FOR OUR REGION...THIS WILL RESULT IN
TEMPERATURES FALLING BACK TO BELOW NORMAL LEVELS FOR MOST IF NOT
ALL OF THIS PERIOD...WHEN DAILY HIGHS WILL MAINLY BE IN THE LOWER
TO MIDDLE 70S...AND NIGHTTIME LOWS WILL RANGE THROUGH THE 50S.

IN TERMS OF PRECIPITATION CHANCES...THE TREND TOWARD COOLER
WEATHER WILL BE USHERED IN BY THE PASSAGE OF A SECONDARY COLD
FRONT LATER TUESDAY AND TUESDAY NIGHT...WHICH WILL PROBABLY BE
ACCOMPANIED BY ANOTHER ROUND OF SCATTERED SHOWERS AND
THUNDERSTORMS AS IT CROSSES OUR REGION. ADDITIONAL SCATTERED
SHOWERS MAY THEN LINGER INTO WEDNESDAY ACROSS THE EASTERN HALF OF
THE AREA IN CONJUNCTION WITH THE PASSAGE OF THE MAIN UPPER LEVEL
TROUGH AXIS AND POSSIBLE LAKE ENHANCEMENT DOWNWIND OF LAKE
ONTARIO...BEFORE INCREASING SURFACE- BASED RIDGING AND DRIER AIR
THEN BRINGS A RETURN TO MAINLY DRY WEATHER FOR BOTH THURSDAY AND
FRIDAY.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
HIGH PRESSURE OVER THE OHIO VALLEY WILL NOSE NORTH ACROSS THE
LOWER GREAT LAKES TODAY. WHILE THIS WILL SUPPLY OUR REGION WITH
FAIR DRY WEATHER FOR THE BULK OF THE DAY...A COUPLE AFTERNOON
SHOWERS OR THUNDERSTORMS WILL BE POSSIBLE AWAY FROM THE
STABILIZING INFLUENCES OF THE LAKES.

VFR CONDITIONS ARE THEN ANTICIPATED FOR TONIGHT AS HIGH PRESSURE
CENTERED TO OUR SOUTH SHOULD REMAIN IN CONTROL.

OUTLOOK...
SUNDAY...VFR.
SUNDAY NIGHT...MAINLY VFR WITH SCATTERED SHOWERS AND THUNDERSTORMS.
MONDAY...VFR TO OCCASIONALLY MVFR WITH SHOWERS AND STORMS LIKELY.
TUESDAY...MAINLY VFR WITH A CHANCE OF A FEW LIGHT SHOWERS.
WEDNESDAY...MAINLY VFR.

&&

.MARINE...
ANOTHER WEAK TROUGH AND RELATIVELY TIGHT SFC PRESSURE GRADIENT
WILL PRODUCE ANOTHER ROUND OF SMALL CRAFT ADVISORY CONDITIONS
TODAY ACROSS THE EASTERN ENDS OF BOTH LAKES ERIE AND ONTARIO.

THIS SAME BASIC PATTERN WILL CONTINUE THROUGH THE WEEKEND WITH
WINDS DROPPING OFF SOME TONIGHT AND EARLY SUNDAY BEFORE INCREASING
TO NEAR SMALL CRAFT ADVISORY CONDITIONS AGAIN ON BOTH LAKES LATER
SUNDAY. THE SMALL CRAFT ADVISORY CONDITIONS MAY LAST SUNDAY NIGHT
INTO MONDAY AS A STRONGER COLD FRONT CROSSES THE REGION.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 11 PM EDT
         THIS EVENING FOR LEZ040-041.
         SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 8 PM EDT
         THIS EVENING FOR LEZ020.
         SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 11 PM
         EDT THIS EVENING FOR LOZ043>045.

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...RSH
MARINE...RSH



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