Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 270221
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1021 PM EDT SUN APR 26 2015

.SYNOPSIS...
PERSISTENT LOW PRESSURE JUST EAST OF NEW ENGLAND WILL BROADEN ITS
INFLUENCE AND BRING CLOUDS AND A FEW SCATTERED SHOWERS TO THE REGION
LATER TONIGHT AND MONDAY. THIS LOW WILL FINALLY PULL AWAY TUESDAY
AND ALLOW DRY WEATHER AND SOME SUNSHINE TO RETURN. THE DRY WEATHER
WILL LAST THROUGH WEDNESDAY BEFORE A WEAK SYSTEM BRINGS THE NEXT
CHANCE OF SHOWERS BY THURSDAY. TEMPERATURES WILL REMAIN ON THE COOL
SIDE THROUGH MONDAY BEFORE WARMING TO NEAR NORMAL FOR THE REST OF
THE WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
A STRONG MID LEVEL VORTICITY MAXIMA OVER QUEBEC WILL CONTINUE TO
ORBIT THE MID LEVEL CLOSED LOW EAST OF MAINE OVERNIGHT. THE
INFLUENCE OF THIS FEATURE ROUNDING THE WESTERN SIDE OF THE CLOSED
LOW WILL FORCE A MID LEVEL TROUGH SLOWLY SOUTH ACROSS NEW ENGLAND
AND THE LOWER LAKES. LARGE SCALE ASCENT WILL INCREASE AHEAD OF THE
TROUGH AS WILL DEEPER MOISTURE...SPREADING SOUTH FROM LAKE ONTARIO
AND THE NORTH COUNTRY DURING THE COURSE OF THE OVERNIGHT INTO
MONDAY. LOW LEVEL FLOW IN THE 925MB-700MB LAYER WILL INCREASE TO
20-25 KNOTS WHICH WILL AID IN ALLOWING SOME WEAK BANDS OF
CONVERGENCE TO FORM. THIS SHOULD ALL BE SUFFICIENT TO SUPPORT A FEW
SCATTERED LIGHT RAIN SHOWERS LATE TONIGHT THROUGH MONDAY ACROSS THE
ENTIRE REGION. COVERAGE SHOULD REMAIN FAIRLY SPOTTY WITH PLENTY OF
RAIN FREE TIME...AND AMOUNTS SHOULD BE KEPT TO LESS THAN A TENTH OF
AN INCH IN MOST LOCATIONS.

BOTH THE NAM AND GFS ARE CONSISTENT WITH PREVIOUS RUNS IN SHOWING A
LOW CLOUD DECK CROSSING THE AREA DURING THE FIRST HALF OF MONDAY.
THE STRATUS MAY BE LOW ENOUGH TO INTERSECT THE HILLS FROM THE
SOUTHERN TIER INTO THE FINGER LAKES AND ALSO ACROSS THE TUG HILL AND
WESTERN ADIRONDACKS. THIS WILL PRODUCE SOME AREAS OF FOG ACROSS THE
HIGHER TERRAIN LATE TONIGHT THROUGH MIDDAY MONDAY. EXPECT THE FOG TO
BE LIMITED TO THE HIGHER TERRAIN...WITH SURFACE DEWPOINTS NOT
GETTING QUITE HIGH ENOUGH TO SUPPORT ANY ADVECTION FOG OFF THE COLD
LAKES.

THE INCREASING CLOUDS WILL HELP TO KEEP TEMPERATURES UP A FEW
DEGREES TONIGHT COMPARED TO RECENT NIGHTS. EXPECT LOWS IN THE UPPER
30S ON THE LAKE PLAINS...AND LOW TO MID 30S ACROSS HIGHER TERRAIN.
EXPECT THE BOUNDARY LAYER TO BE JUST WARM ENOUGH TO SUPPORT ALL RAIN
ACROSS THE HIGHER TERRAIN WHEN THE SCATTERED SHOWERS BEGIN LATE
TONIGHT OR MONDAY MORNING. EXTENSIVE CLOUD COVER ON MONDAY WILL KEEP
HIGHS IN THE UPPER 40S TO AROUND 50 ACROSS LOWER ELEVATIONS AND LOW
TO MID 40S ACROSS HIGHER TERRAIN. NORTHWEST FLOW WILL KEEP THE LAKE
ONTARIO AND LAKE ERIE SHORES IN THE LOWER 40S AS WELL.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
MONDAY NIGHT INTO TUESDAY...EXPECT RISING HEIGHTS ACROSS THE
FORECAST AREA AS A PERSISTENT UPPER-LEVEL LOW SPINS OFF THE NEW
ENGLAND COAST AND SHARP RIDGE AXIS OVER THE UPPER GREAT LAKES BUILDS
IN FROM THE WEST.

INITIALLY MONDAY NIGHT...LOW-LEVEL MOISTURE WILL BE TRAPPED UNDER A
SHALLOW INVERSION IN THE NORTHWESTERLY FLOW WHICH WILL LEAD TO SOME
PATCHY FOG IN THE FAVORED UPSLOPE REGION ACROSS THE SOUTHERN TIER
AND NORTH COUNTRY. HOWEVER...DRIER AIR WILL WORK IN ACROSS THE
REGION FROM THE TOP DOWN...AND SHOULD EVENTUALLY RESULT IN CLEARING
OF ANY REMAINING LOW CLOUDS/STRATUS TUESDAY MORNING.

THUS EXPECT MORE SUNSHINE ACROSS THE AREA BY TUESDAY AFTERNOON
...ALONG WITH 850 MB TEMPERATURES SUBTLY RISING TO AROUND +2C BY
THE AFTERNOON...SHOULD ALLOW MANY INTERIOR LOCATIONS TO SEE THE
UPPER 50S / LOW 60S. THE EXCEPTION WILL BE COOLER TEMPERATURES ALONG
THE SOUTH SHORE OF LAKE ONTARIO AS ONSHORE FLOW OFF THE COOL LAKE
KEEPS TEMPERATURES LOCKED IN THE UPPER 40S/LOW 50S. THE NW FLOW
SHOULD ALLOW KEEP MOST OF THE BUFFALO METRO AREA ON THE WARM SIDE OF
THE LAKE BREEZE.

BY TUESDAY NIGHT EXPECT MOSTLY CLEAR SKIES WITH DECENT RADIATIONAL
COOLING ALLOWING TEMPERATURES TO DROP TO THE MID 30S TO LOWER 40S.

WEDNESDAY LOOKS TO BE A FAIRLY WARM DAY...AS THE SHORTWAVE RIDGING
AND THERMAL RIDGE AXIS SHIFT ACROSS THE FORECAST AREA. 850 MB
TEMPERATURES MAX OUT AROUND +4/+5C WEDNESDAY AFTERNOON...AND
COMBINED WITH MOSTLY SUNNY SKIES SHOULD RESULT IN TEMPERATURES IN
THE MID 60S. COMBINE THESE TEMPERATURES WITH FAIRLY LIGHT WINDS AND
THE RESULT SHOULD BE A FANTASTIC SPRING DAY.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
FAIRLY TYPICAL SPRING WEATHER TO CONTINUE THROUGH THE EXTENDED
FORECAST PERIOD. BY WEDNESDAY NIGHT INTO THURSDAY...MODELS ARE IN
AGREEMENT THAT A NORTHERN STREAM SHORTWAVE WILL INTERACT WITH A
CUTOFF LOW EXITING FROM THE FOUR CORNERS REGION. HOWEVER...THAT IS
WHERE THE AGREEMENT ENDS...AS THE GLOBAL MODELS ALL HANDLE THIS
INTERACTION DIFFERENTLY. LOOKING AT RECENT RUNS OF THE
GGEM/ECMWF/GFS...ABOUT TWO-THIRDS OF THE GUIDANCE IS SIMILAR TO THE
00Z GGEM/ECMWF WHICH FORECAST A WEAK AND DISORGANIZED TROUGH WITH
WARMER TEMPERATURES AND ONLY A LOW CHANCE FOR PRECIPITATION LATE IN
THE WEEK. THE LESS LIKELY 12Z GFS SOLUTION HAS A STRONGER CUT-OFF
LOW DEVELOPING WHICH WOULD BRING COOLER TEMPERATURES AND A BETTER
CHANCE FOR PRECIPITATION. FORECAST WILL USE A CONSENSUS OF ALL
GUIDANCE...WHICH SHOULD EVENTUALLY TREND TO ONE OF THESE TWO CAMPS.
IN GENERAL...THIS APPROACH LEADS TO SLIGHTLY WARMER TEMPERATURES TO
THE PREVIOUS FORECAST WITH LITTLE CHANGE TO POPS.

BY NEXT WEEKEND...THE MODEL CONSENSUS IS TO BUILD A RIDGE ACROSS THE
UPPER GREAT LAKES...WITH SOME NORTHWEST FLOW IN PLACE ACROSS THE
LOWER GREAT LAKES. THIS SHOULD RESULT IN A WARMER WEEKEND AS COLDER
AIR WILL BE SUPPRESSED WELL TO THE NORTH.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
A STACKED LOW OVER THE CANADIAN MARITIMES WILL CIRCULATE INCREASING
AMOUNTS OF LOW LEVEL MOISTURE TO THE SOUTH ACROSS THE REGION DURING
THE COURSE OF THE NIGHT. THIS WILL EVENTUALLY LEAD TO DETERIORATING
CONDITIONS WITH VFR CIGS LOWERING TO MVFR...AND IN MANY AREAS...A
FEW HOURS OF IFR WITHIN A FEW HOURS OF SUNRISE.

NORTHERLY UPSLOPE FLOW WILL PRODUCE THE LOWEST CIGS ACROSS PORTIONS
OF THE SOUTHERN TIER AND FINGER LAKES WHERE STRATUS INTERSECTING THE
HILLS MAY PRODUCE FOG AND IFR VSBY. ACROSS LOWER ELEVATIONS THE IFR
CIGS SHOULD IMPROVE TO MVFR BY LATE MONDAY MORNING...THEN TO VFR
DURING THE AFTERNOON. ACROSS HIGHER TERRAIN EXPECT IFR CIGS THROUGH
EARLY AFTERNOON BEFORE IMPROVING TO MVFR.

ALONG WITH THE LOWER CLOUDS...SCATTERED SHOWERS WILL DEVELOP LATE
TONIGHT AND CONTINUE THROUGH MONDAY. THE GREATEST CONCENTRATION
DURING THE AFTERNOON SHOULD FOCUS ACROSS THE HIGHER TERRAIN OF THE
SOUTHERN TIER...FINGER LAKES...AND EAST OF LAKE ONTARIO SUPPORTED BY
NORTHERLY UPSLOPE FLOW. MOST OF THE RAIN WILL BE LIGHT ENOUGH TO
KEEP VSBY VFR EXCEPT FOR IN THE AREAS OF HIGHER TERRAIN FOG.

OUTLOOK...
MONDAY NIGHT...SCATTERED SHOWERS ENDING. AREAS OF MVFR CIGS LOWER
ELEVATIONS AND IFR CIGS HIGHER TERRAIN.
TUESDAY...ANY MVFR/IFR CIGS IMPROVING TO VFR.
WEDNESDAY...MAINLY VFR.
THURSDAY AND FRIDAY ...AREAS OF MVFR POSSIBLE WITH A CHANCE OF
SHOWERS.

&&

.MARINE...
A PERSISTENT STALLED LOW OVER THE GULF OF MAINE WILL CONTINUE TO
SPIN THROUGH MONDAY AND PRODUCE NORTHWEST WINDS IN THE 10-15 KNOT
RANGE ACROSS THE LOWER LAKES. THIS WILL PRODUCE CHOPPY WAVE ACTION
AT TIMES ALONG THE SOUTH SHORE OF LAKE ONTARIO BUT CONDITIONS WILL
REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA. GENERALLY LIGHT WINDS
ARE EXPECTED TO LAST THROUGH THE MIDDLE OF THE WEEK ON BOTH LAKES.

&&

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

&&

$$

SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK/RSH
SHORT TERM...CHURCH
LONG TERM...CHURCH
AVIATION...HITCHCOCK/RSH
MARINE...HITCHCOCK







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