Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 230815
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
415 AM EDT THU APR 23 2015

.SYNOPSIS...
AN UPPER LEVEL LOW WILL REMAIN STALLED ACROSS QUEBEC AND NORTHERN
NEW ENGLAND BEFORE IT GRADUALLY SLIDES OFF THE MAINE COAST ON SUNDAY.
THIS WILL RESULT IN COOL AND UNSETTLED WEATHER THROUGH FRIDAY WITH
RAIN AND WET SNOW SHOWERS. AS THIS FEATURE MOVES FURTHER AWAY THE
WEATHER IN OUR REGION WILL GRADUALLY IMPROVE WITH SOME SUN AND
SLIGHTLY WARMER TEMPERATURES FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AN UPPER LEVEL LOW NEAR THE ONTARIO/QUEBEC BORDER EARLY THIS MORNING
WILL GRADUALLY MOVE ACROSS QUEBEC INTO NORTHERN NEW ENGLAND THROUGH
TONIGHT. THIS WILL MAINTAIN A CYCLONIC FLOW ALOFT WITH COOL
TEMPERATURES AND SOME SHOWERS. LIFT WILL LARGELY BE DRIVEN BY SUBTLE
FEATURES FROM DISTURBANCES EMBEDDED WITHIN THIS UPPER LOW. 850MB
TEMPERATURES WILL AVERAGE -7C TO -11C DURING THE PERIOD. AT NIGHT
THIS IS COLD ENOUGH FOR MAINLY SNOW SHOWERS...BUT DURING THE DAYTIME
THE BOUNDARY LAYER MAY INITIALLY MELT THE SNOW UNTIL EVAPORATIVE
COOLING CHANGES PRECIPITATION OVER TO SNOW. ALTHOUGH IT IS UNCOMMON
FOR LAKE EFFECT SNOW IN APRIL...TEMPERATURES ALOFT THIS COLD CAN
PRODUCE SOME MODEST LAKE ENHANCEMENT. THIS WILL PROBABLY BE MOST
EVIDENT OFF LAKE ERIE WHERE TEMPERATURES ALOFT WILL BE COLDEST.

IR SATELLITE SHOWS ONE DISTURBANCE EAST OF LAKE ONTARIO WHICH SHOULD
EXIT EAST BY DAYBREAK. THEN ANOTHER SUBTLE DISTURBANCE PIVOTING
ACROSS EASTERN MICHIGAN EARLY THIS MORNING BRING ANOTHER ROUND OF
SNOW SHOWERS THROUGH THIS MORNING. THIS IS CAPTURED BY A CONSENSUS
OF MESOSCALE GUIDANCE WHICH BRINGS THE BEST QPF FROM W-E ACROSS
SOUTHERN PORTIONS OF THE CWA THROUGH THIS MORNING. THIS MAY BRING AN
INCH OR TWO OF SNOW...MAINLY TO GRASSY SURFACES ACROSS HIGHER
TERRAIN IN THE SOUTHERN TIER AND SKI COUNTRY. SHOWERS SHOULD BE
LESS WIDESPREAD THIS AFTERNOON...BUT DIURNAL HEATING COMBINED WITH
SURFACE CONVERGENCE MAY PRODUCE SOME RAIN OR SNOW SHOWERS EAST OF
LAKE ONTARIO AND LAKE ERIE.

THE UPPER LOW MOVING INTO NEW ENGLAND TONIGHT WILL BRING IN
PROGRESSIVELY DRIER AIR INTO WESTERN PORTIONS TONIGHT WHICH WILL
CAUSE SNOW SHOWERS TO TAPER OFF IN THESE AREAS. HOWEVER...ANOTHER
DISTURBANCE IS FORECAST TO PIVOT ACROSS THE REGION WHICH IS LIKELY TO
BRING SOME SNOW SHOWERS EAST OF LAKE ONTARIO. MOST HIGH RESOLUTION
GUIDANCE (00Z NAM/ARW/WRF/RGEM) SHOWS QPF ASSOCIATED WITH THIS
HOWEVER TIMING VARIES A BIT DUE TO DIFFERENCES IN TIMING AND POSITION
OF THE UPPER LOW. ALSO...THE WESTERLY FLOW WILL PRODUCE A
CONVERGENCE BOUNDARY DOWN THE LENGTH OF LAKE ONTARIO AND SOME
UPSLOPING BOTH OF WHICH SHOULD ENHANCE LIFT AND BRING AN INCH OR TWO
OF SNOW.

OTHERWISE TEMPERATURES WILL BE BELOW NORMAL. THE COLD AIR ALOFT
SUPPORTS COOL HIGH TEMPERATURES WHICH IS MORE IN LINE WITH THE
COOLER RGEM/SREF TEMPERATURE GUIDANCE. HIGHS TODAY SHOULD RANGE FROM
THE MID 30S ACROSS HIGHER TERRAIN TO THE LOWER 40S IN THE WARMER
VALLEYS WHERE A FEW BREAKS OF SUN ARE POSSIBLE. LOWS TONIGHT SHOULD
BE BELOW FREEZING IN MOST AREAS...HOWEVER CLOUDS AND WIND SHOULD
KEEP MOST AREAS FROM DROPPING BELOW THE UPPER 20S.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
FRIDAY AND SATURDAY A NARROW RIDGE OF HIGH PRESSURE WILL SQUEEZE
BETWEEN TWO STORM SYSTEM...THE CLOSED UPPER LEVEL LOW TO OUR EAST
OVER NEW ENGLAND...AND A MIDWEST STORM SYSTEM. THIS AREA OF HIGH
PRESSURE WILL LEAVE WNY DRY...WHILE OUR EASTERN ZONES MAY SEE A
PASSING SHOWER OF SNOW OR RAIN FRIDAY WITH THE UPPER LEVEL LOW STILL
IN CLOSE PROXIMITY.

FOR FRIDAY...THIS AREA OF HIGH PRESSURE WILL ADVANCE FROM THE
CENTRAL GREAT LAKES SOUTHEASTWARD TOWARDS THE WESTERN MID ATLANTIC
STATES. THOUGH THE HIGH PRESSURE WILL BE WEAKENING...A STRONG ENOUGH
OF A SUBSIDENCE INVERSION OVER THE REGION COMBINED WITH STILL
CYCLONIC FLOW ALOFT SHOULD PROMOTE PLENTY OF CLOUD COVER FROM
LINGERING MOISTURE.

ON SATURDAY THIS AREA OF HIGH PRESSURE WILL WEAKEN OVER THE
REGION...BUT INCREASE SUBSIDENCE AND DRIER AIR SHOULD ALLOW FOR
ADDITIONAL AMOUNTS OF SUNSHINE. GREATEST SUNSHINE WILL LIKELY BE
ACROSS THE GENESEE VALLEY AND FINGER LAKES REGION...WHILE OUR
WESTERN AND EASTERN ZONES ARE BRUSHED BY PASSING CLOUDS FROM NEARBY
STORM SYSTEMS.

TEMPERATURES FRIDAY WILL BE ON THE CHILLY SIDE UNDER MOSTLY CLOUDY
SKIES. HIGHS GENERALLY IN THE 40S...OR ABOUT 15F DEGREES BELOW
NORMAL. ON SATURDAY WARMING ALOFT COMBINED WITH ADDITIONAL SUNSHINE
SHOULD ALLOW MOST AREAS TO RISE INTO THE UPPER 40S TO AROUND 50F.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
THE EXPANSIVE UPPER LOW OVER NEW ENGLAND WILL CONTINUE TO DOMINATE
OUR WEATHER AS WE MOVE INTO THE COMING WEEK. MODELS ARE COMING INTO
BETTER AGREEMENT ON THE TRACK OF THE LOW AS IT RETROGRADES FROM THE
CANADIAN MARITIMES BACK ACROSS NEW ENGLAND...WITH PASSING SHORTWAVES
AROUND THE LOW TRACKING SHORTWAVE TROUGHS AS FAR WEST AS OUR REGION
MONDAY AND MONDAY NIGHT. AS THIS OCCURS...EXPECT CLOUDS AND SHOWERS
TO CREEP BACK INTO THE FORECAST ACROSS MUCH OF THE FORECAST AREA BY
MONDAY AS ATLANTIC MOISTURE WRAPS BACK ACROSS THE LOWER GREAT LAKES.
FORTUNATELY...AS THIS AIRMASS WILL BE
ATLANTIC-SOURCED...TEMPERATURES SHOULD NOT TAKE MUCH OF A HIT.
INDEED...WE SHOULD SEE A EVER SO SLIGHT WARMING TREND THROUGH THE
PERIOD AS THIS HEAVILY MODIFIED AIRMASS ADVECTS ACROSS THE REGION
FROM THE NORTHEAST WITH HIGHS IN THE 50S AND LOWS IN THE 30S...WHICH
WILL FALL JUST A FEW DEGREES FROM NORMAL.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
DISTURBANCES WILL PIVOT AROUND A STALLED UPPER LEVEL LOW WHICH WILL
REMAIN STALLED ACROSS QUEBEC AND NORTHERN NEW ENGLAND THROUGH FRIDAY.
THERE WILL PRIMARILY BE VFR CONDITIONS...BUT SNOW SHOWERS WILL
PRODUCE LOCALLY LOWER CONDITIONS WITH VSBY 1/2SM TO 2SM IN STEADIER
SNOW SHOWERS. THESE WILL BE DIFFICULT TO FORECAST...BUT THE BEST
CHANCE APPEARS TO BE WITH AN IMPULSE WHICH IS PICKED UP BY MOST
GUIDANCE THAT IS FORECAST TO MOVE ACROSS THE REGION BETWEEN 09Z AND
15Z. THERE MAY BE SOME DIURNALLY DRIVEN SNOW SHOWERS THURSDAY
AFTERNOON...THEN ANOTHER DISTURBANCE IS LIKELY TO PIVOT ACROSS THE
NORTH COUNTRY (ART) THIS EVENING. FORECAST CONFIDENCE IN TIMING
INDIVIDUAL SNOW SHOWERS IS LOW...BUT ANY IMPACTS WILL BE RELATIVELY
BRIEF.

OUTLOOK...
FRIDAY...VFR/MVFR WITH SCATTERED RAIN AND WET SNOW SHOWERS MAINLY
EAST OF LAKE ONTARIO.
SATURDAY AND SUNDAY...MAINLY VFR WITH A CHANCE OF A FEW LIGHT
RAIN/SNOW SHOWERS ACROSS THE NORTH COUNTRY.
MONDAY...VFR/MVFR WITH A CHANCE OF RAIN SHOWERS.

&&

.MARINE...
AN UPPER LEVEL LOW ACROSS QUEBEC AND NORTHERN NEW ENGLAND WILL
MAINTAIN A PERSISTENT WESTERLY COMPONENT FLOW THROUGH FRIDAY. THESE
WINDS WILL FINALLY DROP OFF THIS WEEKEND WHEN HIGH PRESSURE RIDGES
TOWARD THE REGION. THIS WILL RESULT IN SMALL CRAFT ADVISORIES ON ALL
THE LAKES TODAY...WITH THE STRONGEST WINDS ON EASTERN PORTIONS OF
LAKE ONTARIO. SMALL CRAFT ADVISORIES END FROM WEST TO EAST AS OUTLINED BELOW.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LEZ040-
         041.
         SMALL CRAFT ADVISORY UNTIL 8 AM EDT SATURDAY FOR
         LOZ043>045.
         SMALL CRAFT ADVISORY UNTIL 11 PM EDT FRIDAY FOR LOZ042.

&&

$$

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







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