Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 221447
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1047 AM EDT WED APR 22 2015

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL SLOWLY SPIRAL ACROSS THE
GREAT LAKES AND NORTHEAST REGION THIS WEEK. THIS FEATURE WILL
PROVIDE FOR COOL...AND UNSETTLED WEATHER THROUGH FRIDAY. AS THE
UPPER LEVEL LOW FOCUSES UPON NEW ENGLAND THIS WEEKEND...SOME
IMPROVEMENT WILL BE SEEN ACROSS THE EASTERN GREAT LAKES REGION AS
SUNSHINE AMOUNTS INCREASE AND AIR TEMPERATURES SLIGHTLY WARM.

&&

.NEAR TERM /THROUGH TONIGHT/...
AN UPPER LEVEL LOW IS CENTERED JUST TO THE NORTH OF MICHIGAN THIS
MORNING. MULTIPLE SHORTWAVE TROUGHS ROTATING AROUND THIS SYSTEM ARE
PRODUCING SCATTERED RAIN SHOWERS...WITH A MORE DEFINED SHORTWAVE
TROUGH OVER LAKE MICHIGAN THIS MORNING.

EXPECT SCATTERED RAIN SHOWERS ACROSS THE REGION TODAY. A SOUTHWEST WIND
WILL DEVELOP STABILIZING LAKE BREEZES AGAIN WITH AREAS DOWNWIND OF
BOTH LAKES ERIE AND WATERTOWN LIKELY DRY WITH A BIT OF SUNSHINE.

THIS AFTERNOON RAIN SHOWERS WILL BLOSSOM ON THE LAKE ERIE LAKE
BREEZE BOUNDARY WITH SHOWERS LIKELY TO FORM ACROSS THE SOUTHERN TWO
TIERS OF COUNTIES. THOUGH CAPE VALUES WILL BE LOW...STEEPING MID
LEVEL LAPSE RATES IN CONJUNCTION WITH UPWARD LIFT ALONG THE LAKE
BREEZE BOUNDARY AHEAD OF THE UPPER LEVEL LOW SHOULD BE SUFFICE TO
GENERATE SHOWERS. SHOWERS ARE ALSO LIKELY TO FORM ON THE NORTHERN
LAKE BREEZE BOUNDARY WITH ADDED LIFT FROM THE SOUTHERN LAKE ONTARIO
BOUNDARY. THESE SHOWERS OVER THE NORTHERN NIAGARA FRONTIER LATE THIS
AFTERNOON WILL DIVE SOUTHEASTWARD INTO THE CENTER OF WNY BEFORE
DIMINISHING THIS EVENING WITH THE LOSS OF DAYTIME HEATING.

STABLE LAKE SHADOWS ARE LIKELY TO DEVELOP AGAIN TODAY NORTHEAST OF
LAKES ERIE AND ONTARIO. LOCAL CLEARING LATE THIS MORNING AND INTO
THE AFTERNOON HOURS IS LIKELY ACROSS METRO BUFFALO AND TOWARDS
ROCHESTER...AS WELL AS ACROSS NORTHERN JEFFERSON COUNTY. WINDS WILL
BECOME GUSTY NORTHEAST OF LAKE ERIE DURING THE AFTERNOON WITH GUSTS
AROUND 35 MPH TO 40 MPH UNDER THE CLEARING.

COLD AIR ADVECTION LATER THIS AFTERNOON WILL INCREASE TONIGHT BEHIND
THE SHORTWAVE FROM THE WESTERN GREAT LAKES. THIS SHORTWAVE WILL AID
IN SHIFTING THE UPPER LEVEL LOW EASTWARD SOME THROUGH THE NIGHT.

AS CYCLONIC FLOW CONTINUES ACROSS THE REGION THIS EVENING SCATTERED
RAIN SHOWERS WILL BE POSSIBLE WITH THE RAIN CHANGING TO SNOW WITHIN
THE COLD AIR ADVECTION. AS TEMPERATURES AT 850 HPA DROP TO -8C TO
-10C BY THURSDAY MORNING REGION WIDE THERE WILL BE A CHANCE FOR SNOW
SHOWERS BY THE END OF THE NIGHT. HOWEVER AS WE COOL THE AMOUNT OF
SHOWER ACTIVITY WILL BE WANING THROUGH THE NIGHT. ANY SNOW
ACCUMULATION WILL LIKELY BE RESERVED FOR THE HIGHER ELEVATIONS...THE
SOUTHERN TIER IN PARTICULAR WHERE A HALF INCH OF SNOW IS POSSIBLE.

AIR TEMPERATURES WILL BE SOME 10 TO 15F DEGREES BELOW NORMAL WITH
HIGHS TODAY LARGELY IN THE 40S. TONIGHT TEMPERATURES WILL DROP TO
NEAR FREEZING...AND BELOW FREEZING ACROSS HIGHER TERRAIN OF SW NYS
AND THE TUG HILL.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
BELOW NORMAL TEMPERATURES WILL REMAIN IN PLACE ACROSS OUR FORECAST
AREA DURING THIS PERIOD...AND FOR THAT MATTER...THE FORESEEABLE
FUTURE. A VERY LARGE LONGWAVE TROUGH WILL BE CENTERED OVER NORTH
AMERICA DURING THIS PERIOD. THE PLANETARY SCALE TROUGH WILL BE
ANCHORED BY A STATIONARY...LONG LIVED VORTEX IN THE VCNTY OF THE
CANADIAN MARITIMES AND A YOUTHFUL CLOSED LOW NEAR THE ALEUTIANS.
BETWEEN THESE VORTICES WILL BE A COMPLEX SPLIT FLOW WITH CANADIAN
BASED AIR DOMINATING THE COUNTRY POLEWARD OF 40N.

AS AN EXAMPLE...WHILE OUR H85 TEMPS WILL MODIFY FROM EARLY MARCH
LEVELS...THEY ARE NOT FORECAST TO CLIMB ABOVE ZERO C. MEANWHILE...
SOME GOOD NEWS CAN BE TAKEN FROM THE EXPECTATION THAT UNEVENTFUL...
GENERALLY PCPN FREE WEATHER IS ANTICIPATED FOR THE VAST MAJORITY OF
THIS PERIOD. OUR REGION WILL BE FAR ENOUGH REMOVED FROM THE
GERIATRIC STACKED LOW OVER THE CANADIAN MARITIMES SO THAT DRIER
CONTINENTAL AIR FROM CANADA WILL DOMINATE THE LOWER GREAT LAKES.
THIS WILL ESPECIALLY BE THE CASE AS WE GET CLOSER TO THE WEEKEND.

AS FOR THE DAY TO DAY DETAILS...
AN ELONGATED...TWIN VORTICITY BASED CLOSED LOW WILL STRETCH FROM THE
NORTHERN REACHES OF MANITOBA TO NEW ENGLAND ON THURSDAY...WHILE A
DEEP 992MB SFC REFLECTION WILL SPIN IN PLACE OVER THE LOWER ST
LAWRENCE VALLEY. THIS WILL KEEP OUR FORECAST AREA WITHIN A SOMEWHAT
MOIST CYCLONIC FLOW...WITH SUBTLE SHORTWAVES AND DIURNALLY INDUCED
INSTABILITY SUPPORTING SOME WIDELY SEPARATED RAIN AND WET SNOW
SHOWERS. AS HAS BEEN THE CASE FOR A COUPLE DAYS...A LOT OF THIS SFC
BASED INSTABILITY WILL BE NEUTRALIZED NEAR LAKES ERIE AND ONTARIO.
H85 TEMPS AROUND -8C WILL PRODUCE A MID MARCH ENVIRONMENT AS OUR
AFTERNOON MAX TEMPS WILL ONLY RANGE FROM THE 30S ACROSS THE BULK OF
THE SRN TIER TO THE LOW-MID 40S ACROSS THE LAKE PLAIN STRETCHING
FROM BUF TO SYR. TO ADD INSULT TO INJURY...A GUSTY WEST WIND WILL
GENERATE APPARENT TEMPS IN THE 20S AND 30S THROUGHOUT THE DAY.

AS THE CLOSED LOW CONSOLIDATES OVER MAINE THURSDAY NIGHT...SFC HIGH
PRESSURE WILL BUILD FROM THE UPPER GREAT LAKES TO THE OHIO VALLEY.
IT IS AT THIS POINT THAT SOME DRIER AIR WILL WORK ACROSS THE LOWER
GREAT LAKES. THIS SHOULD ENCOURAGE MAINLY PCPN FREE CONDITIONS
OVERNIGHT...ALTHOUGH THERE COULD BE SOME RESIDUAL MIXED SHOWERS
EARLY ON WITH MORE PERSISTENT ACTIVITY POSSIBLE ACROSS THE NORTH
COUNTRY.  TEMPS WILL DROP INTO THE LOWER 30S FOR MOST AREAS WITH
WIDESPREAD 20S ACROSS THE SRN TIER AND TUG HILL.

ON FRIDAY...THE SYNOPTIC CONDITIONS WILL CHANGE VERY LITTLE AS A
STATIONARY STACKED LOW WILL BE CENTERED OVER MAINE WHILE RIDGING
WILL EXTEND FROM THE UPPER GREAT LAKES AND OHIO VALLEY TO THE
SOUTHEAST COAST. THE SFC PRESSURE GRADIENT BETWEEN THE TWO SYSTEMS
WILL CONTINUE TO GENERATE BRISK WESTERLY WINDS...WHICH WILL JUST ADD
TO THE CHILL OF MAX TEMPS IN THE UPPER 30S AND 40S. IN TERMS OF
PCPN...H85 TEMPS WILL STILL BE IN THE VCNTY OF -8C...AND THIS WILL
PROMOTE JUST ENOUGH LAND BASED INSTABILITY IN THE LOWER LEVELS TO
JUSTIFY LOW CHC POPS. ONE COULD EASILY ARGUE THOUGH DRIER AIR IN THE
MID LEVELS WILL NEGATE THIS POTENTIAL OVER THE WESTERN COUNTIES. THE
HIGHEST POPS (40) WILL REMAIN OVER THE EASTERN LAKE ONTARIO REGION
WHERE DEEPER MOISTURE WILL BE IN PLACE CLOSER PROXIMITY OF THE UPPER
LOW.

MOST OF OUR FORECAST AREA SHOULD THEN FIND ITSELF IN THE `SWEET
SPOT` ON SATURDAY AS HIGH PRESSURE WILL BE FOUND ACROSS ALL OF THE
GREAT LAKES...WHILE UNSETTLED WEATHER WILL PRODUCE FAIRLY WIDESPREAD
SHOWERS ACROSS THE REMAINDER OF THE EASTERN HALF OF THE COUNTRY.
ONLY THE EASTERN LAKE ONTARIO REGION WILL HAVE THE POTENTIAL FOR ANY
HIT AND MISS SHOWERS...AS PARTLY SUNNY SKIES SHOULD PREVAIL. WHILE
THE MERCURY WILL REMAIN BELOW NORMAL...IT WILL BE A LITTLE MILDER
WITH TEMPS CLIMBING BACK INTO THE 50S FOR THE FIRST TIME IN THREE
DAYS.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE MEDIUM RANGE GUIDANCE PACKAGES HAVE BECOME INCREASINGLY
DIVERGENT UPON THEIR SOLUTION FOR THIS PERIOD...AND AS A RESULT...
FORECAST CONFIDENCE HAS DROPPED OFF SIGNIFICANTLY. THE OPERATIONAL
GFS PROBABLY DEPICTS THE MOST EXTREME SOLUTION WITH A DEVELOPING
DEEP CLOSED LOW OVER THE MID WEST...WHILE THE ECMWF FAVORS A SPLIT
FLOW OVER THE SAME AREA WITH THE OLD MARITIMES CLOSED LOW ROTATING
BACK ACROSS NEW ENGLAND.

WILL TAKE A COMPROMISE BETWEEN CONTINUITY AND THE MORE PESSIMISTIC
(BUT REALISTIC LOOKING) ECMWF...WHICH WILL LEAD TO A CLOUDIER
FORECAST WITH SLGT TO LOW CHC POPS FOR SHOWERS. WILL NOT STRAY FAR
FROM THE TEMPS IN CONTINUITY... AS THERE IS A 10 DEG F DIFFERENCE
BETWEEN THE DIFFERENT ENSEMBLE CAMPS FOR MONDAY AND TUESDAY.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
AT 12Z A CLOSED UPPER LEVEL LOW TO OUR NORTHWEST CONTINUES TO SPIRAL
SHOWERS ACROSS THE GREAT LAKES REGION...WITH MAINLY VFR FLIGHT
CONDITIONS. SHOWERS ACTIVITY THAT HAS BLOSSOMED OVER MUCH OF THE
REGION WITH A PASSING WEAK COLD FRONT HAS NOW LARGELY EXITED THE
REGION EASTWARD. EXPECT ANOTHER INCREASE IN SHOWERS THIS AFTERNOON
ON LAKE BREEZE BOUNDARIES COUPLED WITH THE LEADING EDGE OF AN UPPER
LEVEL VORT MAX ROTATING ACROSS THE REGION.

HIGHER ELEVATIONS SUCH AS THE SOUTHERN TIER...AND THE TUG HILL EAST
OF LAKE ONTARIO MAY DROP TO MVFR...OTHERWISE THE BULK OF ACTIVITY
SHOULD BE VFR.

PRECIPITATION TYPE WILL BE ALL LIQUID THROUGH THE AFTERNOON
HOURS...BUT AS COLD AIR ADVECTION INCREASES THROUGH THE
AFTERNOON...SOME EVENING WET SNOWFLAKES...AND OVERNIGHT SNOW IS
LIKELY ACROSS THE SOUTHERN TIER...INCLUDING THE KJHW TERMINAL. THERE
WILL ALSO BE A CHANCE FOR SOME WET SNOWFLAKES ACROSS LOWER
ELEVATIONS LATE OVERNIGHT THURSDAY NIGHT. IN ANY SNOW THROUGH THE
OVERNIGHT TIME PERIOD THERE MAY BE BRIEF IFR VSBYS. THIS AGAIN WILL
LARGELY BE CONFINED TO THE SOUTHERN TIER AND THE KJHW TERMINAL.

FOR THE WINDS...STABLE LAKE SHADOWS ARE LIKELY TO DEVELOP NORTHEAST
OF LAKES ERIE AND ONTARIO THIS AFTERNOON...WITH LOCAL CLEARING NEAR
KBUF AND KART. WINDS WILL BECOME GUSTY NORTHEAST OF LAKE ERIE DURING
THE AFTERNOON WITH GUSTS AROUND 30 KNOTS IN THE CORRIDOR FROM KBUF
TO KROC.

OUTLOOK...
THURSDAY THROUGH FRIDAY...VFR/MVFR WITH SCATTERED TO OCCASIONALLY
MORE NUMEROUS RAIN SHOWERS...WHICH MAY BE MIXED WITH AND/OR CHANGE
TO WET SNOW SHOWERS AT NIGHT.
SATURDAY AND SUNDAY...MAINLY VFR WITH A CHANCE OF A FEW LIGHT
RAIN/SNOW SHOWERS ACROSS THE NORTH COUNTRY.

&&

.MARINE...
A SOUTHWEST TO WEST FLOW TODAY THROUGH THE END OF THE WEEK WILL
MAINTAIN SMALL CRAFT CONDITIONS ON THE LAKES FOR A GOOD PORTION OF
THE TIME. EXPECT SOUTHWEST WINDS AND WAVES TO INCREASE ON LAKE
ERIE...THE UPPER NIAGARA RIVER AND THE WESTERN HALF OF LAKE ONTARIO
TODAY WITH SOUTHWEST WINDS TOPPING 18 KNOTS. AS COLD AIR ADVECTION
INCREASES TONIGHT WAVES WILL STEADILY INCREASE OVERNIGHT SUCH THAT
SMALL CRAFT CONDITIONS ARE EXPECTED ON BOTH LAKES. TONIGHT STRONGEST
WINDS WILL BE FOUND ON LAKE ONTARIO AS WESTERLY FLOW NEARS 20 TO 25
KNOTS ON LAKE ONTARIO. OVER A SHORTER FETCH ON LAKE ERIE THESE
WESTERLY WINDS WILL REMAIN LARGELY BELOW 20 KNOTS.

WAVES AND WINDS WILL DIMINISH ON LAKE ERIE TOMORROW
AFTERNOON...THOUGH WINDS AND WAVES WILL BE AT SMALL CRAFT ADVISORY
OR GREATER LEVELS ON LAKE ONTARIO INTO LATE FRIDAY...AND POSSIBLY
SATURDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THURSDAY FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
         LEZ020.
         SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 8 AM
         EDT SATURDAY FOR LOZ043.
         SMALL CRAFT ADVISORY UNTIL 11 PM EDT FRIDAY FOR LOZ042.
         SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 8 AM EDT
         SATURDAY FOR LOZ045.
         SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 AM EDT
         SATURDAY FOR LOZ044.

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...THOMAS/WCH
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...THOMAS
MARINE...THOMAS






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