Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 131646
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1246 PM EDT SUN JUL 13 2014

.SYNOPSIS...
A FRONTAL SYSTEM WILL CROSS THE REGION TODAY AND TONIGHT...BRINGING
MORE HUMID CONDITIONS ALONG WITH SOME SHOWERS AND THUNDERSTORMS.
CONTINUED UPPER LEVEL TROUGHING WILL THEN KEEP AT LEAST SOME
ADDITIONAL SCATTERED SHOWERS AND THUNDERSTORMS GOING RIGHT THROUGH
TUESDAY...BEFORE DRIER AND COOLER WEATHER RETURNS FOR THE SECOND
HALF OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
SHOWERS WITH SCATTERED EMBEDDED THUNDERSTORMS CONTINUE TO TRACK FROM
WEST TO EAST ACROSS THE FORECAST AREA IN AN AREA OF ENHANCED THETA-E
ADVECTION AND MOISTURE CONVERGENCE JUST AHEAD OF AN APPROACHING
SURFACE AND MID-LEVEL TROUGH EXTENDING FROM A LOW CENTERED NEAR
JAMES BAY. A 120KT H250 JET STREAK ROUNDING THE LOW INTO THE UPPER
GREAT LAKES WILL CONTINUE TO SHUNT THE SURFACE AND MID-LEVEL FEATURE
OFF TO THE EAST THIS AFTERNOON. IN FACT SURFACE OBS OVER SOUTHERN
ONTARIO SHOW THE TROUGH AXIS JUST TO OUR WEST WITH A WELL DEFINED
LINE OF SHOWER AND EMBEDDED THUNDERSTORMS MARKING IT`S POSITION
NICELY. THIS AREA OF SHOWERS/THUNDERSTORMS WILL MAKE IT`S WAY ACROSS
THE NIAGARA FRONTIER OVER THE NEXT 1-2 HOURS AND CONTINUE TO CROSS
THE REST OF THE FORECAST AREA THROUGH THE REST OF THE
AFTERNOON...EXITING THE NORTH COUNTRY EARLY THIS EVENING. THE
PASSAGE OF THESE SHOWERS AND THUNDERSTORMS WILL BE MARKED BY BRIEF
PERIODS OF HEAVY RAIN AND GUSTS OF 30-40MPH AT MOST. MESOANALYSIS
INDICATES VERY MODEST LOW-LEVEL LAPSE RATES AND VIRTUALLY NO
LOW-LEVEL INSTABILITY...SUGGESTING THE FEARED MIXING OF HIGHER WINDS
ALOFT TO THE SURFACE IS NOT OCCURRING...LIKELY DUE TO CLOUD COVER
AND RAIN-COOLED AIR. SURFACE OBS OVER SOUTHERN ONTARIO THAT HAVE
ONLY SHOWN GUSTS TO AROUND 35MPH ALSO SUPPORT THIS...THUS AM NOT
EXPECTING A SEVERE THREAT FOR THE REST OF THE AFTERNOON.

THE BULK OF THE SHOWER ACTIVITY SHOULD END WITH THE PASSAGE OF THE
TROUGH THIS AFTERNOON/EARLY EVENING. NONETHELESS...WITH CONTINUED
CYCLONIC FLOW ALOFT AND LINGERING LOW-LEVEL MOISTURE...CANNOT RULE
OUT THE RE-DEVELOPMENT OF SHOWERS AND POSSIBLY A THUNDERSTORM OR
TOWN LATER THIS AFTERNOON AWAY FROM THE LAKES. THIS ACTIVITY WILL BE
DEPENDENT ON THE DEGREE OF CLEARING WE GET BEHIND THE TROUGH...AND
IT WILL BE IN A NARROW WINDOW BETWEEN THE CLEARING BEHIND THE TROUGH
AND THE LOSS OF DIURNAL HEATING ONCE THE SUN SETS. THUS...HAVE
ELECTED TO LEAVE CHANCE POPS IN THROUGH THE EARLY EVENING HOURS.

EXPECT POPS TO TREND DOWNWARDS THOUGH THIS EVENING WITH THE LOSS OF
DIURNAL HEATING CAUSING ANY LINGERING CONVECTION TO DISSIPATE. IT
WILL STILL REMAIN QUIET MUGGY...WITH DEWPOINTS STILL IN THE
60S...AND THIS WILL KEEP LOWS CORRESPONDINGLY MILD...IN THE LOW TO
MID 60S.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
A HIGHLY ANOMALOUS UPPER LEVEL PATTERN DURING THIS SHORT TERM PERIOD
WILL SET THE STAGE FOR SOME VERY COOL WEATHER DURING THE MID AND
LATTER PORTIONS OF THE WEEK. HGT AND TEMP DEPARTURES WITHIN THIS
PATTERN WILL BE HIGHLIGHTED BY 3 STD ANOMALIES IN A VERY ROBUST WEST
COAST RIDGE WITH CORRESPONDINGLY LOW VALUES OVER THE MISSISSIPPI
VALLEY. THESE ARE DEPARTURES THAT HAVE A RETURN INTERVAL OF ONCE IN
A GREATER THAN 30 YEAR PERIOD.

WHILE THIS PATTERN WILL DE-AMPLIFY LATER IN THE WEEK...VERY CHILLY
AIR WILL HAVE ALREADY BEEN DISCHARGED OUT OF CANADA ACROSS THE UPPER
GREAT LAKES AND INTO THE MISSISSIPPI AND OHIO VALLEYS. FOR OUR
REGION THOUGH...WHILE WE WILL EXPERIENCE COOLER THAN NORMAL
WEATHER...THE NEWSWORTHY SHOT OF CANADIAN AIR WILL ONLY BE A
GLANCING SHOT FOR THE LOWER GREAT LAKES. THIS IS PROBABLY PUTTING
THE CART BEFORE THE HORSE THOUGH AS WE WILL HAVE TO WORK THROUGH
SOME SUMMERY CONVECTIVE WEATHER FIRST.

A DEEP UPPER LEVEL VORTEX OVER NORTHERN ONTARIO THIS EVENING WILL
SPLIT INTO TWO CENTERS BY MIDDAY MONDAY...AS ONE VIGOROUS SHORTWAVE
WITHIN THE CENTER WILL LIFT TOWARDS JAMES BAY WHILE ITS TWIN WILL
DIG SOUTHEAST ACROSS THE UPPER GREAT LAKES. THIS WILL NOT ONLY PULL
APART THE WELL DEFINED UPPER LEVEL CIRCULATION...BUT MORE
IMPORTANTLY...THE MOVEMENT OF THE SECOND SHORTWAVE WILL HELP TO PUMP
UP SOME LOW LEVEL RIDGING OVER THE LOWER LAKES. WHILE THE ENSUING
WEAK SUBSIDENCE WILL TRY TO KEEP THINGS FAIRLY SUBDUED OVER THE
FORECAST AREA ON MONDAY...THERE COULD BE JUST ENOUGH DIURNALLY BASED
INSTABILITY AND MOISTURE TO GENERATE SOME SCATTERED AFTERNOON
CONVECTION. PWAT VALUES FOR THE EASTERN PART OF THE FORECAST AREA
WILL BE IN THE VCNTY OF 1.5"...BUT WITH A WIND FIELD FAVORING A
PROGRESSIVE FLOW FOR ANY STORMS AND A RELATIVELY THIN CAPE
PROFILE...THE POTENTIAL FOR SEVERE WEATHER OR HYDRO RELATED ISSUES
WILL BE MINIMAL. AS MENTIONED...THE BULK OF MONDAY SHOULD BE RAIN
FREE. IT WILL BE SOMEWHAT LESS HUMID THAN THE DAY BEFORE AS WELL
WITH TEMPERATURES TOPPING OUT TO WITHIN A FEW DEGREES OF 80 (MID 80S
GENESEE VALLEY).

AS THE VIGOROUS SHORTWAVE PLOWS ACROSS THE UPPER GREAT LAKES MONDAY
NIGHT...THE VARIOUS GUIDANCE PACKAGES DIVERGE IN THE HANDLING OF THE
CORRESPONDING SFC FEATURES. ALL OF THE NORTH AMERICAN MODELS ARE IN
AGREEMENT THAT A COLD FRONT WILL PUSH ACROSS OUR FORECAST AREA...
WHILE THE ECMWF STANDS ALONE IN SUGGESTING THAT A SFC WAVE DEVELOPS
ALONG THE FRONT...THEREBY SLOWING ITS PROGRESSION ACROSS OUR AREA
UNTIL THE NEXT DAY (TUES). THE ECMWF IS TRENDING CLOSER TO ITS
US/CANADIAN COUNTERPARTS...BUT IS STUBBORN IN GIVING UP ON THE
NOTION OF A WAVE MOVING UP ALONG THE FRONT. GIVEN THE LACK OF RUN TO
RUN AND MODEL TO MODEL CONSISTENCY...WILL STAY CLOSE TO
CONTINUITY...WHICH WAS LARGELY BASED ON THE SLOWER ECMWF SOLUTION.
THAT BEING SAID...WILL USE CHC POPS MONDAY NIGHT WITH A TREND
TOWARDS HIGHER POPS DURING THE COURSE OF THE NIGHT AS THE
AFOREMENTIONED WAVE PUSHES ACROSS LAKE ERIE.

THE COOLER AIR WILL THEN SLOWLY WORK ITS WAY ACROSS OUR FORECAST
AREA ON TUESDAY AS THE PASSING OF THE AFOREMENTIONED WAVE WILL
FINALLY ALLOW THE COLD FRONT TO PUSH ACROSS THE REGION. EVEN THE
SLOWER ECMWF HAS THE COLD FRONT CLEARING OUR FORECAST AREA BY MID
AFTERNOON...SO DIURNALLY...THE TIMING IS NOT FAVORABLE FOR STRONG TO
SEVERE THUNDERSTORM ACTIVITY. GIVEN THE APPARENT LACK OF
INSTABILITY...WILL BACK OFF ON ANY SEVERE WEATHER WORDING THAT WAS
USED IN THE HAZARDOUS WEATHER OUTLOOK. THE UNSETTLED WEATHER AND
ASSOCIATED CLOUD COVER SHOULD HOLD MAX TEMPERATURES IN THE 70S.

FOR TUESDAY NIGHT...THE MODELS TEND TO CONVERGE ON THE SCENARIO OF
SPRAWLING HIGH PRESSURE OVER NORTHERN PLAINS EXPANDING TO THE EAST
ACROSS THE GREAT LAKES AND OHIO VALLEY WITH COOLER AND DRIER AIR
MAKING ITS WAY OVER THE LOWER GREAT LAKES. OVERNIGHT TEMPERATURES
ACROSS MUCH OF OUR REGION WILL DROP BACK INTO THE 50S...WITH 40S
ANTICIPATED OVER MUCH OF THE SRN TIER.

THE LARGE SFC HIGH WILL DRIFT EAST ACROSS THE OHIO VALLEY AND LOWER
GREAT LAKES WEDNESDAY AND WEDNESDAY NIGHT. WHILE SUBSIDENCE
ASSOCIATED WITH THIS FEATURE WILL PROVIDE THE REGION WITH GENERALLY
FAIR WEATHER...H5 TEMPS IN THE MINUS TEENS COULD OFFER ENOUGH
INSTABILITY WEDNESDAY AFTERNOON TO SUPPORT SOME ISOLATED SHOWERS.
OTHERWISE IT WILL BE QUITE COOL WITH H85 TEMPS AROUND 8C LEADING TO
AFTERNOON HIGHS IN THE 60S AND LOWER 70S (10 DEG F BELOW NORMAL)
WHILE WEDNESDAY NIGHT LOWS WILL ONCE AGAIN BE IN THE 40S (SRN TIER)
AND 50S.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
THE HIGHLY AMPLIFIED PATTERN OF THE DAYS PRECEDING THIS PERIOD WILL
GIVE WAY TO A BROAD LONGWAVE TROUGH THAT WILL COVER MUCH OF THE
LOWER 48. THIS WILL INITIALLY KEEP TEMPERATURES BELOW NORMAL
THROUGHOUT THE GREAT LAKES REGION...BUT WITHOUT A DIRECT FEED OF
CANADIAN AIR TO REPLENISH THE QUICKLY MODIFYING AIRMASS...MERCURY
LEVELS WILL STEADILY CLIMB BACK TOWARDS NORMAL LEVELS.

MEANWHILE...EXPANSIVE HIGH PRESSURE WILL KEEP OUR FORECAST RAIN
FREE. THE SFC HIGH WILL BE CENTERED OVER THE OHIO VALLEY AS WE OPEN
THIS PERIOD...BUT AS WE PROGRESS INTO NEXT WEEKEND...THE HIGH WILL
DRIFT OFF THE EAST COAST. THE RETURN FLOW AROUND THIS FEATURE WILL
AID IN THE MODIFICATION OF THE ONCE COOL AIRMASS.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
WIDESPREAD SHOWERS...WITH ISOLATED EMBEDDED THUNDERSTORMS...ARE
CONTINUING TO MAKE THEIR WAY ACROSS WESTERN AND NORTH-CENTRAL NY
THIS MORNING. RADAR TRENDS SHOW A BRIEF BREAK IN CONVECTION ACROSS
THE NIAGARA FRONTIER FOR THE NEXT 30-60 MINUTES BEFORE ANOTHER BATCH
OF SHOWERS NEAR LONG POINT ONTARIO MOVES BACK INTO THE AREA. AFTER
THAT BATCH MOVES THROUGH BY 18Z...WE SHOULD SEE CONVECTION DISSIPATE
AND CONDITIONS RETURN TO VFR ACROSS KBUF/KIAG AS THE
SURFACE/MID-LEVEL TROUGH AND ASSOCIATED MOISTURE CONVERGENCE MOVES
OFF TO THE EAST. SIMILARLY...CONDITIONS AT KROC/KART WILL IMPROVE
LATER IN THE AFTERNOON...AROUND 19-23Z RESPECTIVELY...AS THE TROUGH
MOVES THROUGH. IN ADDITION TO THE CONVECTION...GUSTY SOUTHWEST WINDS
WILL CONTINUE ACROSS WESTERN NY IN THE WAKE OF THE TROUGH...WITH
LAKE BREEZE ENHANCEMENT OCCURRING AS WELL.

GIVEN THE UPPER LEVEL TROUGHING WILL STILL BE IN PLACE ACROSS THE
REGION...THERE IS A POSSIBILITY THAT WE COULD SEE SCATTERED SHOWERS
AND THUNDERSTORMS BREAK OUT AGAIN THIS AFTERNOON...PARTICULARLY
ACROSS THE SOUTHERN TIER AND FINGER LAKES...HOWEVER THIS WILL BE
DEPENDENT ON HOW MUCH CLEARING WE SEE BEHIND THIS INITIAL ROUND OF
CONVECTION. OTHERWISE...CONVECTION WILL CONTINUE TO TREND
DOWNWARDS...ALONG WITH WINDS...THROUGH THIS EVENING WITH WIDESPREAD
IMPROVEMENT TO VFR CONDITIONS OVERNIGHT.


OUTLOOK...
MONDAY...MAINLY VFR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS.
TUESDAY...VFR/MVFR IN SCATTERED SHOWERS AND THUNDERSTORMS.
WEDNESDAY AND THURSDAY...MAINLY VFR.

&&

.MARINE...
A FRONTAL SYSTEM WILL CROSS THE LOWER GREAT LAKES TODAY AND TONIGHT
WHILE BRINGING SOME SHOWERS AND THUNDERSTORMS TO THE REGION. IN
ADDITION...A BRIEF PERIOD OF ADVISORY-LEVEL WINDS IS EXPECTED TODAY
IN MOST LOCATIONS AS THIS SYSTEM CROSSES THE AREA...WITH THE EASTERN
PORTIONS OF THE LAKES ALSO LIKELY SEEING WAVES BUILD TO LOW-END
ADVISORY LEVELS FOR A TIME.

LOOKING A BIT FURTHER OUT...GENERALLY UNSETTLED WEATHER WILL PERSIST
THROUGH TUESDAY...THOUGH WINDS AND WAVES SHOULD DROP BACK BELOW
ADVISORY LEVELS.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ020-
         040-041.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
         LOZ030-042>045.

&&

$$

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






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