Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 271109
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
709 AM EDT MON APR 27 2015

.SYNOPSIS...
A COOL...MOIST NORTHERLY FLOW WILL CONTINUE ACROSS THE EASTERN GREAT
LAKES REGION TODAY WITH SCATTERED RAIN SHOWERS. THIS SHOWER ACTIVITY
WILL DIMINISH THROUGH THE OVERNIGHT HOURS TONIGHT AS AN UPPER LEVEL
LOW PRESSURE DRIFTS FARTHER OUT TO SEA. DRY WEATHER AND CLEARING
SKIES WILL RETURN TUESDAY AND WILL LAST THROUGH WEDNESDAY BEFORE A
WEAK SYSTEM BRINGS THE NEXT CHANCE OF SHOWERS BY THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
WATER VAPOR IMAGERY THIS MORNING DISPLAYS AN UPPER LEVEL LOW
CONTINUING TO SPIRAL OFF THE ATLANTIC CANADA COASTLINE. A
VORTICITY MAXIMA IS SEEN DROPPING ACROSS SOUTHERN LAKE HURON THIS
MORNING...CREATING A WESTWARD UPPER LEVEL TROUGH OF LOW PRESSURE
THAT WILL DROP ACROSS OUR REGION THIS MORNING.

REGIONAL RADARS THIS MORNING DISPLAY LIGHT RAIN SHOWERS AND DRIZZLE
DROPPING SOUTHWARD ACROSS THE NIAGARA FRONTIER AND DOWN TOWARDS THE
SOUTHERN TIER. WILL INCREASE POPS FOR A FEW HOURS THIS MORNING TO
ACCOUNT FOR THIS ACTIVITY. WITH DAYTIME HEATING EXPECT THIS ACTIVITY
TO WANE MID MORNING SUCH THAT JUST SCATTERED LIGHT SHOWERS REMAIN
FOR THE REMAINDER OF THE DAY ACROSS WNY. THERE WILL BE A FAIR AMOUNT
OF DRY TIME TOO ACROSS WNY TODAY.

EAST OF LAKE ONTARIO REGIONAL RADARS DISPLAY JUST SOME LIGHT
SPRINKLES. WITH THE VORTICITY MAXIMA FARTHER AWAY FROM THIS REGION
THIS MORNING EXPECT THE BETTER PART OF THE MORNING TO REMAIN DRY.

AS THIS UPPER LEVEL TROUGH PASSES...LOW LEVEL MOISTURE CONVERGENCE
ON A NORTHERLY FLOW WILL INCREASE. THIS MOISTURE WILL PRODUCE LIGHT
RAIN SHOWERS THROUGH THE DAY...WITH ACTIVITY HIGHLIGHTED OVER THE
UPSLOPE REGIONS SOUTH OF BUFFALO AND ROCHESTER...AS WELL AS EAST OF
LAKE ONTARIO. ACTIVITY EAST OF LAKE ONTARIO WILL LIKELY FALL THROUGH
THE AFTERNOON HOURS AS LOW LEVEL MOISTURE INCREASES. RAINFALL
AMOUNTS SHOULD BE KEPT TO LESS THAN A TENTH OF AN INCH IN MOST
LOCATIONS.

THOUGH TEMPERATURES AT 925 HPA WILL BE A DEGREE WARMER THAN
YESTERDAY...ADDITIONAL CLOUD COVER TODAY WILL LIKELY HOLD AFTERNOON
TEMPERATURES A DEGREE OR SO COLDER THAN SUNDAY. THIS WILL PLACE MANY
AREAS IN THE MID 40S TO AROUND 50...WHICH IS A SOLID 10 DEGREES
BELOW NORMAL.

TONIGHT AS THE UPPER LEVEL LOW DRIFTS FARTHER OUT TO SEA A WEAK
RIDGE OF HIGH PRESSURE WILL PRESS EASTWARD ACROSS THE GREAT LAKES
REGION. RAIN SHOWER ACTIVITY WILL END THROUGH THE EVENING AND
OVERNIGHT HOURS...THOUGH SKIES MAY REMAIN FAIRLY CLOUDY THROUGH THE
NIGHT. IF CLEARING DOES DEVELOP PATCHY AREAS OF FOG WILL DEVELOP.
LIKELIEST AREAS FOR THIS WOULD BE FAR WESTERN NEW YORK AND THE HIGHER
TERRAIN OF THE TUG HILL REGION. LOWS TONIGHT WILL RANGE FROM THE MID
30S ACROSS THE INLAND SOUTHERN TIER...TO LOWER 40S NEAR THE LAKE
PLAINS.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
A CLOSED UPPER LOW IN THE CANADIAN MARITIMES WILL GRADUALLY YIELD TO
A NARROW 500 MB RIDGE WHICH WILL BUILD INTO OUR REGION. THIS WILL
ALLOW SURFACE HIGH PRESSURE ACROSS THE UPPER LAKES ON TUESDAY TO
SPREAD WESTWARD INTO OUR REGION BY WEDNESDAY.

TUESDAY SHOULD START OFF WITH AT LEAST PARTIAL CLOUD COVER AND
PERHAPS SOME PATCHY FOG. 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. PARTLY TO
MOSTLY SUNNY SKIES COMBINED WITH 850MB TEMPS OF AROUND +2C SHOULD
RESULT IN WARMER TEMPERATURES. EXPECT HIGHS ON TUESDAY TO BE IN THE
LOWER 60S ACROSS INTERIOR SECTIONS...WITH COOLER TEMPERATURES IN THE
UPPER 40S TO LOWER 50S SOUTH OF LAKE ONTARIO AND LAKE ERIE. THE NW
FLOW SHOULD 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 INTO THE
MID 30S TO LOWER 40S. THERE MAY BE SOME PATCHY FOG IN THE SOUTHERN
TIER VALLEYS.

WEDNESDAY LOOKS TO BE A WARM DAY...AS THE SHORTWAVE RIDGING AND
THERMAL RIDGE AXIS SHIFT ACROSS THE FORECAST AREA. MODEL CONSENSUS
850 MB TEMPERATURES RISE TO AROUND +5C WITH THE GFS A NOTABLE COOLER
OUTLIER. THIS CONSENSUS COMBINED WITH MOSTLY SUNNY SKIES SHOULD
RESULT IN HIGHS IN THE MID TO UPPER 60S ON THE WARM SIDE OF THE LAKE
BREEZE...WITH HIGHS IN THE 50S ALONG THE IMMEDIATE LAKESHORES. THIS
COMBINED WITH FAIRLY LIGHT WINDS SHOULD RESULT SHOULD BE A FANTASTIC
SPRING DAY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THERE CONTINUES TO BE A SIGNIFICANT DIFFERENCE IN MODEL GUIDANCE
THROUGH MUCH OF THE LONG TERM PERIOD. THIS DIFFERENCE MAINLY STEMS
FROM HOW MUCH ENERGY WILL BREAK OFF FROM A SHORTWAVE NEAR HUDSON BAY
ON TUESDAY NIGHT. THE OPERATIONAL GFS HAS CONSISTENTLY BROKEN OFF
MORE ENERGY WHICH DROPS ACROSS THE GREAT LAKES ON WEDNESDAY NIGHT
AND THEN RESULTS IN A CUT-OFF LOW NEAR THE MID ATLANTIC WHICH TAKES
OVER FROM THE CANADIAN MARITIME LOW. THE 00Z GGEM/ECMWF (AND THE
NAM) BREAK OFF CONSIDERABLY LESS ENERGY WHICH TAKES THE SAME
TRACK...BUT IS NOT ENOUGH TO CUT-OFF SO INSTEAD IT PIVOTS OFF
THE MID ATLANTIC AND FEEDS INTO THE CANADIAN MARITIME LOW. IT IS
ALSO WORTH NOTING THE MAJORITY OF GFS ENSEMBLE MEMBERS SIDE WITH THE
GGEM/ECMWF...WITH ENSEMBLE MOS REFLECTING LOW FORECAST CONFIDENCE
FOR THIS TIMEFRAME. THE DIFFERENCES BETWEEN THESE TWO SOLUTIONS (AND
IT WILL PROBABLY BE ONE OR THE OTHER) IS SIGNIFICANT. THE GFS
SOLUTION WOULD RESULT IN SHOWERS THURSDAY AND FRIDAY AND MUCH COOLER
TEMPERATURES INTO THE WEEKEND WHILE THE ECMWF/GGEM SOLUTIONS WOULD
RESULT IN ONLY A SMALL CHANCE FOR SHOWERS AND WARMER TEMPERATURES.

BASED ON THE MODEL CONSENSUS...WE STILL VIEW THE GFS SOLUTION AS
LESS LIKELY...AND GIVEN THE RELATIVELY BINARY OPTIONS (CUT-OFF LOW
OR NOT) THE FORECAST WILL LEAN TOWARD THE ECMWF/GGEM SOLUTIONS. THIS
SAID...THERE STILL IS A CHANCE THE GFS WILL VERIFY WHICH WOULD
REQUIRE SIGNIFICANT ADJUSTMENTS TO THE CURRENT FORECAST.

WHICH EVER SOLUTION VERIFIES...IT APPEARS A BROAD RIDGE OF HIGH
PRESSURE WILL BUILD ACROSS MUCH OF THE CONUS ON SUNDAY...WITH A ZONAL FLOW
NEAR THE CANADIAN BORDER. THIS WILL BRING SEASONABLY WARM
TEMPERATURES AS COLDER AIR WILL BE SUPPRESSED WELL TO THE NORTH.

&&

.AVIATION /11Z MONDAY THROUGH FRIDAY/...
AT 12Z MVFR AND VFR FLIGHT CONDITIONS WERE FOUND ACROSS THE REGION
WITH A FEW RAIN SHOWERS DROPPING SOUTHWARD ACROSS FAR WESTERN NEW
YORK. AS A COOL NORTHERLY FLOW INCREASES LOW LEVEL MOISTURE ACROSS
THE REGION THIS MORNING EXPECT AN EXPANSION SOUTHEASTWARD OF LIGHT
SHOWERS ACROSS WNY THROUGH 15Z...THEN A DECREASE IN COVERAGE AREA IS
EXPECTED. BRIEF IFR IS POSSIBLE ACROSS THE SOUTHERN TIER THIS
MORNING AS LOW LEVEL MOISTURE CREATES A LOW STRATUS DECK OF CLOUDS.
ELSEWHERE MVFR FLIGHT CONDITIONS ARE LIKELY WITHIN SCATTERED RAIN
SHOWERS. THE GENESEE VALLEY AND THE EASTERN LAKE ONTARIO SHORELINE
WILL START THE DAY WITH A DECK OF MVFR CIGS...THAT SHOULD RISE TO
VFR THIS AFTERNOON.

SHOWERS WILL INCREASE AGAIN THIS AFTERNOON EAST OF LAKE ONTARIO
WHERE AN UPSLOPE FLOW NEAR THE CLOSED UPPER LEVEL LOW WILL LIKELY
BRING RAIN SHOWERS TO THE TUG HILL REGION. ALL SHOWER ACTIVITY WILL
SLOWLY DIMINISH THROUGH THE OVERNIGHT HOURS WITH A RETURN TO VFR.
THAT SAID ANY CLEARING OF THE SKIES MAY ALLOW FOR SOME PATCHY FOG TO
FORM THAT WILL REDUCE VISIBILITIES. THE BEST CHANCE FOR THIS TO
HAPPEN WILL BE ACROSS THE HILLS SOUTH OF BUFFALO WHERE SOME
LOCALIZED IFR VSBYS ARE POSSIBLE THE SECOND HALF OF THE NIGHT.

OUTLOOK...
TUESDAY...ANY MVFR/IFR CIGS IMPROVING TO VFR.
WEDNESDAY...MAINLY VFR.
THURSDAY AND FRIDAY ...AREAS OF MVFR POSSIBLE WITH A CHANCE OF
SHOWERS.

&&

.MARINE...
NORTHWEST WINDS WILL AVERAGE 10 TO 15 KNOTS ON THE EASTERN GREAT
LAKES TODAY THROUGH TOMORROW. THESE WINDS WILL BACK SOME TO WESTERLY
ON WEDNESDAY AS THE UPPER LEVEL LOW EXITS EASTWARD AND WEAK SURFACE
HIGH PRESSURE BUILDS EASTWARD TOWARDS THE EASTERN GREAT LAKES. WINDS
WILL CONTINUE TO REMAIN LIGHT ON WEDNESDAY WITH WAVE HEIGHTS OVER
THE NEXT 72 TO 96 HOURS 3 FEET OR LESS.

&&

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

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...THOMAS
SHORT TERM...APFFEL
LONG TERM...APFFEL/CHURCH
AVIATION...THOMAS
MARINE...THOMAS






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