Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 290618
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
118 AM EST MON DEC 29 2014

.SYNOPSIS...
HIGH PRESSURE WILL BUILD ACROSS THE GREAT LAKES THROUGH MONDAY. THIS
WILL BRING COOLING TEMPERATURES WHICH WILL HELP IT FEEL MUCH MORE
LIKE MID-WINTER THROUGH THE COMING WEEK WITH MAINLY DRY CONDITIONS
OUTSIDE OF A CHANCE OF SOME WEAK LAKE EFFECT SNOW SHOWERS. BETTER
CHANCES FOR LAKE EFFECT SNOW ARRIVE BY LATE WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
IR SATELLITE SHOWS SKIES HAVE CLEARED ACROSS THE FORECAST AREA AS OF
06Z AHEAD OF A SURFACE TROUGH APPROACHING FROM THE NORTHWEST.
CLOUDINESS WILL RETURN TOWARD DAYBREAK WITH AN INCREASE IN MOISTURE
FROM THE PASSAGE OF THE TROUGH. THIS INCREASE IN MOISTURE AND
SYNOPTIC LIFT WILL BRING CHANCES OF LIGHT SNOW SHOWERS OR FLURRIES
LATER THIS MORNING THEN DURING THE DAY MONDAY. HAVE REMOVED THE
MENTION OF FREEZING DRIZZLE AS IR CLOUD TOP TEMPS ALONG THE
APPROACHING TROUGH ARE -18C TO -20C. WHICH IS PLENTY COLD ENOUGH FOR
ICE CRYSTAL FORMATION IN THE CLOUDS.

850 MB TEMPERATURES DROPPING TO NEAR -15C MONDAY. THIS WILL RESULT
IN A COLD DAY MONDAY...BUT WITH AIR MASS RATHER DRY AND LOW
INVERSION HEIGHTS...LOOKING FOR AT LEAST PARTIAL SUNSHINE WITH A FEW
FLURRIES WITHIN ANY POCKETS OF STRATOCU WITH A CLOUD LAYER RESIDING
AROUND -12C. HIGH TEMPERATURES GENERALLY IN THE MID TO UPPER 20S.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
THE FIRST 24 HOURS OR SO OF THIS PERIOD WILL BE CHARACTERIZED BY A
PROGRESSIVELY COLDER BUT ALSO FAIRLY DRY NORTHWESTERLY TO WEST-
NORTHWESTERLY FLOW ACROSS THE GREAT LAKES AND NORTHEAST. COUPLED
WITH THE RATHER LOW CAPPING INVERSION THAT WILL BE IN PLACE...THIS
SHOULD MERELY TRANSLATE INTO PARTLY TO MOSTLY CLOUDY SKIES AND SOME
SCATTERED FLURRIES FOR MUCH OF THE REGION. THE ONE EXCEPTION TO THIS
WILL BE ACROSS AREAS EAST-SOUTHEAST OF LAKE ONTARIO DURING
TUESDAY...WHERE A SOMEWHAT MORE FAVORABLE MOISTURE AND A SLIGHTLY
HIGHER CAP SHOULD ALLOW FOR AT LEAST SOME SCATTERED NUISANCE-TYPE
LAKE EFFECT SNOW SHOWERS.

TUESDAY NIGHT AND WEDNESDAY...THE LOW-LEVEL FLOW ACROSS OUR REGION
WILL SLOWLY BACK TO WESTERLY AND THEN WEST-SOUTHWESTERLY AS HIGH
PRESSURE INITIALLY SITUATED ALONG THE FRONT RANGE OF THE ROCKIES
BUILDS SOUTHEASTWARD INTO THE SOUTHERN PLAINS...AND AS BROAD LOW
PRESSURE SLIDES FROM NORTH CENTRAL CANADA INTO HUDSON BAY. AT THE
SAME TIME...850 MB TEMPS WILL REMAIN PLENTY COLD ENOUGH FOR A LAKE
RESPONSE AND SYNOPTIC-SCALE MOISTURE WILL ALSO INCREASE A LITTLE.
COUPLED WITH A BIT OF BUMP IN INVERSION HEIGHTS AND AN INCREASING
FETCH ACROSS THE LAKES...THIS SHOULD ALLOW FOR A SOMEWHAT BETTER
OPPORTUNITY FOR LAKE EFFECT SNOW SHOWERS EAST AND EVENTUALLY EAST-
NORTHEAST OF THE LAKES...PARTICULARLY DOWNWIND OF LAKE ONTARIO WHERE
LAKE EFFECT PARAMETERS NOW APPEAR FAVORABLE ENOUGH FOR A LIKELIHOOD
OF SNOW ALONG WITH SOME ACCUMULATIONS OF A COUPLE INCHES OR SO ABOUT
EVERY 12 HOURS. OUTSIDE OF THE MAIN LAKE EFFECT AREAS...CONDITIONS
SHOULD JUST BE DRY AND COLD WITH A FEW FLURRIES.

TEMPERATURE-WISE...SLOW BUT STEADY COLD AIR ADVECTION WILL RESULT IN
850 MB TEMPS INITIALLY IN THE -12C TO -16C RANGE AT THE START OF THE
PERIOD FALLING TO BETWEEN -16C AND -18C BY TUESDAY NIGHT AND
WEDNESDAY. UNDER THIS REGIME...DAYTIME HIGHS INITIALLY IN THE MID TO
MID TO UPPER 20S ON TUESDAY WILL FALL BACK TO THE LOWER AND MID 20S
BY WEDNESDAY...WHILE NIGHTTIME LOWS DIP INTO THE MID AND UPPER TEENS
SOUTH OF LAKE ONTARIO BY TUESDAY NIGHT...WITH EVEN COLDER READINGS
OF AROUND 10 ABOVE FOUND ACROSS THE NORTH COUNTRY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE WEDNESDAY NIGHT THROUGH THURSDAY NIGHT TIME FRAME WILL BE
CHARACTERIZED BY A CONTINUED WEST-SOUTHWESTERLY TO SOUTHWESTERLY LOW
LEVEL FLOW ACROSS OUR REGION AS LOW PRESSURE OVER HUDSON BAY SHIFTS
INTO NORTHERN QUEBEC AND SWINGS AN ATTENDANT WEAK SURFACE TROUGH
TOWARD AND EVENTUALLY INTO NEW YORK STATE...WHILE SPRAWLING HIGH
PRESSURE OVER THE SOUTHERN PLAINS SLIDES EAST TO THE CAROLINA
COASTLINE. UNDER THIS PATTERN...TEMPS ALOFT WILL SLOWLY WARM BUT
WILL STILL REMAIN COLD ENOUGH TO SUPPORT A LAKE RESPONSE...WITH
THESE ONLY RECOVERING TO THE VICINITY OF -12C BY THURSDAY NIGHT.

UNDER SUCH CONDITIONS...THE CONSEQUENT LAKE RESPONSE EAST-NORTHEAST
AND NORTHEAST OF THE LAKES WILL BE GREATLY INFLUENCED BY THE DEGREE
OF SYNOPTIC-SCALE MOISTURE AVAILABLE...AS WELL AS THE HEIGHT OF THE
CAPPING INVERSION. AS HAS BEEN THE CASE THE PAST COUPLE OF DAYS...
THESE LATTER FACTORS LOOK TO BE CONSIDERABLY MORE FAVORABLE OVER AND
DOWNWIND OF LAKE ONTARIO...WHERE THE LARGE-SCALE ENVIRONMENT NOW
LOOKS FAVORABLE ENOUGH TO WARRANT A LOWER-END LIKELIHOOD OF LAKE
EFFECT SNOW/SNOW SHOWERS THROUGHOUT...ALONG WITH THE POTENTIAL FOR
AT LEAST SOME MODEST ACCUMULATIONS. MEANWHILE OVER LAKE ERIE...MORE
LIMITED MOISTURE AND A NOTABLY LOWER CAP SHOULD KEEP ANY LAKE EFFECT
SNOW SHOWERS MUCH MORE SCATTERED AND LIGHTER IN NATURE...WITH JUST
SOME MINOR NUISANCE-TYPE ACCUMULATIONS APPEARING POSSIBLE AT THIS
JUNCTURE. OUTSIDE OF THE LAKE EFFECT AREAS...CONDITIONS SHOULD JUST
BE COLD AND DRY...WITH TEMPERATURES REMAINING A LITTLE BELOW
SEASONAL AVERAGES.

ON FRIDAY...ANY LAKE EFFECT ACTIVITY DOWNWIND OF THE LAKES SHOULD
WEAKEN AND EVENTUALLY FALL APART ALTOGETHER AS MOISTURE DIMINISHES
AND THE CAPPING INVERSION CRASHES FOLLOWING THE SURFACE TROUGH
PASSAGE...AND AS THE LOW LEVEL FLOW BECOMES LIGHTER AND INCREASINGLY
SHEARED. ELSEWHERE...CONDITIONS SHOULD AGAIN REMAIN DRY.

AS WE HEAD INTO NEXT WEEKEND...OUR FOCUS WILL THEN TURN BACK TO THE
SYNOPTIC SCALE AS ANOTHER DEVELOPING CUTTER-TYPE LOW PRESSURE SYSTEM
OVER TEXAS AND THE GULF COAST STATES LIFTS NORTHEASTWARD AND TOWARD
OUR REGION. WHILE THE MEDIUM RANGE GUIDANCE REMAINS IN GENERAL
AGREEMENT ON THIS OVERALL PATTERN...THERE IS ALSO MUCH DISAGREEMENT
ON THE FORWARD SPEED OF THIS SYSTEM AND EXACT TRACK IT WILL TAKE...
WITH THIS LIKELY ARISING FROM CONTINUED RUN-TO-RUN AND MODEL-
TO-MODEL VARIATIONS IN THE DEGREE OF PHASING BETWEEN THE INCIPIENT
PARENT SOUTHERN STREAM SHORTWAVE AND THE NORTHERN BRANCH OF THE JET
STREAM.

GIVEN THE RESULTANT FORECAST UNCERTAINTY...HAVE ELECTED TO STICK
CLOSER TO WPC GUIDANCE AND OUR EXISTING CONTINUITY FOR THE LATTER
PORTIONS OF THE EXTENDED PERIOD...WITH A GENERAL WARMUP ACCOMPANIED
BY BROADBRUSH CHANCE POPS FRIDAY NIGHT THROUGH SATURDAY NIGHT...
ALONG WITH A BROAD TRANSITION FROM SNOW TO RAIN AND BACK AGAIN...
FOLLOWED BY A RETURN TO DRIER WEATHER AND MORE SEASONABLE TEMPS TO
CLOSE OUT THE PERIOD.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE AND DRIER AIR WILL CONTINUE TO SPREAD INTO THE REGION
WITH CLEAR SKIES AT 06Z. A WEAK SURFACE TROUGH WILL CROSS THE LOWER
GREAT LAKES THIS MORNING. SHALLOW MOISTURE AND WEAK LIFT WILL KEEP
LOW CHANCES OF SNOW SHOWERS FLURRIES BUT TIMING/AREAL CONFIDENCE TOO
LOW FOR TAFS AT THIS TIME.

OUTLOOK...
MONDAY THROUGH TUESDAY...VFR/MVFR CIGS.
WEDNESDAY THROUGH FRIDAY...POSSIBLE IFR IN WSW LAKE EFFECT
-SHRA...MVFR/VFR ELSEWHERE.

&&

.MARINE...
ARCTIC HIGH PRESSURE BUILDING OVER THE GREAT LAKES WILL HELP TO
BRING MORE RELAXED WINDS AND SUBSIDING WAVES TODAY. SMALL CRAFT
ADVISORIES MAY BE DROPPED LATER THIS MORNING IF THE DOWNWARD TREND
IN WINDS AND WAVES CONTINUES. THE RELATIVELY LIGHT NORTHWEST WINDS
WILL CONTINUE FOR THE FIRST PART OF THE COMING WEEK BEFORE WINDS
BACK TO THE SOUTHWEST ON WEDNESDAY AND STRENGTHEN AGAIN AHEAD OF
ANOTHER LOW DROPPING OUT OF THE CANADIAN ARCTIC. THIS WILL
POTENTIALLY BRING ANOTHER ROUND OF SMALL CRAFT ADVISORIES.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
         LOZ043>045.
         SMALL CRAFT ADVISORY UNTIL 7 AM EST THIS MORNING FOR
         LOZ042.

&&

$$

SYNOPSIS...TMA
NEAR TERM...SMITH
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...SMITH
MARINE...SMITH






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