Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 220236
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
936 PM EST SUN DEC 21 2014

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN IN PLACE THROUGH MONDAY AND PROVIDE ONE
MORE DAY OF DRY WEATHER. INCREASING SOUTHERLY WINDS WILL BRING A
SIGNIFICANT WARMING TREND TUESDAY AND WEDNESDAY WITH TEMPERATURES
SOARING TO WELL ABOVE AVERAGE. ALONG WITH THE WARMTH A FEW LIGHT
SHOWERS WILL DEVELOP TUESDAY. A STRONG AREA OF LOW PRESSURE WILL
THEN MOVE THROUGH THE CENTRAL GREAT LAKES AND PRODUCE RAIN ON
WEDNESDAY FOLLOWED BY STRONG WINDS AND A FEW LIGHT RAIN OR WET SNOW
SHOWERS FOR CHRISTMAS DAY.

&&

.NEAR TERM /THROUGH MONDAY/...
THE MAIN FORECAST CHALLENGE THROUGH THE NEAR TERM CONTINUES TO
REVOLVE AROUND THE EVER PRESENT LOW STRATUS AND ITS EVOLUTION.
IR SATELLITE IMAGERY THIS EVENING SHOWING THICK STRATUS DOMINATING
MOST OF THE REGION. NAM POINT SOUNDINGS CONTINUE TO SHOW ABUNDANT
LOW LEVEL MOISTURE TRAPPED BENEATH A STEEP SUBSIDENCE INVERSION
AROUND 3K FEET...AND THIS WILL CONTINUE TO SUPPORT WIDESPREAD
STRATUS THROUGH TONIGHT. BOUNDARY LAYER FLOW WILL BECOME LIGHT
SOUTHERLY OVERNIGHT...SO EVEN IN AREAS NEAR LAKE ONTARIO WHERE A FEW
BREAKS ARE POSSIBLE THIS EVENING THE STRATUS WILL LIKELY MOVE BACK
IN OVERNIGHT. THERE WILL BE LITTLE DIURNAL RANGE WITH MOST AREAS
STAYING CLOUDY. EXPECT LOWS IN THE MID 20S IN MOST AREAS AND UPPER
TEENS ACROSS THE NORTH COUNTRY.

ON MONDAY SOUTH TO SOUTHEAST RETURN FLOW WILL INCREASE. THE
DEVELOPING SOUTHERLY DOWNSLOPE FLOW WILL HELP TO FINALLY ERODE THE
LOW STRATUS FROM THE LOWER ELEVATIONS OF THE LAKE PLAINS WITH
INCREASING AMOUNTS OF SUNSHINE. THE STRATUS MAY BE MORE DIFFICULT TO
DISLODGE ACROSS THE HIGHER TERRAIN OF THE INTERIOR SOUTHERN TIER...
FINGER LAKES...AND TUG HILL REGION WHERE CLOUDS MAY LINGER THROUGH
MOST OF THE DAY. WARM ADVECTION WILL INCREASE IN THE MID LEVELS
DURING THE AFTERNOON...BUT THIS WILL JUST BRING A MODEST INCREASE IN
MID LEVEL CLOUD WITH ANY LIGHT PRECIP REMAINING ACROSS THE OHIO
VALLEY AND MID ATLANTIC. LOW/MID LEVEL WARM ADVECTION WILL BOOST
TEMPS SEVERAL DEGREES OVER RECENT DAYS...WITH UPPER 30S ON THE LAKE
PLAINS OF WESTERN NY AND MID 30S ON THE HILLS AND NORTH COUNTRY.
SOME OF THE TYPICALLY WARMER LOCATIONS IN THE GENESEE VALLEY MAY
PUSH 40.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
THE FOCUS THROUGH MUCH OF THIS WEEK WILL BE ON A STORM EXPECTED TO
DEVELOP OVER THE NORTHERN GULF STATES LATER TUESDAY THEN MERGE WITH
A NORTHERN STREAM LOW ACROSS THE GREAT LAKES ON CHRISTMAS EVE.
THIS WILL BRING VERY MILD TEMPERATURES AND MODERATE TO AT TIMES
HEAVY RAINFALL ON CHRISTMAS EVE FOLLOWED BY A PERIOD OF
POSSIBLY STRONG WINDS BEHIND A COLD FRONT.

LEADING UP TO CHRISTMAS EVE THE WEATHER WILL BE FAIRLY QUIET WITH
TEMPERATURES TRENDING TO ABOVE AVERAGE AND A LOW CHANCE OF RAIN.
A RIDGE OF HIGH PRESSURE SURFACE AND ALOFT WILL LIE ACROSS THE
NORTHEAST STATES THROUGH TUESDAY AS AN AMPLIFYING LONGWAVE TROUGH
DIGS ACROSS THE CENTRAL STATES. ON MONDAY NIGHT THROUGH TUESDAY
NIGHT STRENGTHENING SOUTHERLY FLOW WILL ADVECT INCREASING MOISTURE
NORTHWARD ACROSS OUR REGION WHICH WILL BRING OVERCAST SKIES WHILE
WARM ADVECTION AND ISENTROPIC LIFT AHEAD OF THE DEVELOPING SURFACE
LOW WILL BRING LOW CHANCES OF A SHOWER ACROSS UPSTATE NEW YORK.
MOISTURE PROFILES DO NOT BECOME FULLY SATURATED UNTIL LATE TUESDAY
WITH MUCH OF THE LIGHT SHOWERS BEFOREHAND DRYING UP BEFORE REACHING
THE GROUND. IT IS WORTH A MENTION THAT ANY PRECIP THAT COULD REACH
THE SURFACE EARLY TUESDAY WHEN TEMPS ARE STILL HOVERING NEAR
FREEZING MAY FALL AS A LIGHT WINTERY MIX ACROSS THE HIGHER TERRAIN.
THE BETTER CHANCES FOR PRECIP WILL COME TUESDAY NIGHT ACROSS THE
SOUTHERN TIER. SURFACE TEMPERATURES AND ESPECIALLY BOUNDARY LAYER
TEMPS SHOULD WARM SUFFICIENTLY TUESDAY NIGHT TO KEEP TEMPS WELL
ABOVE FREEZING SO PLAIN RAIN WOULD BE POSSIBLE HERE.

THE STRENGTHENING SOUTHERLY FLOW WILL KEEP OUR TEMPERATURES CLIMBING
AHEAD OF THE DEVELOPING SURFACE LOW. MONDAY NIGHT THROUGH TUESDAY WE
WILL CONTINUE TO SEE 850MB TEMPS INCREASE TO AROUND +10C. MOST AREAS
WILL REMAIN AT OR ABOVE FREEZING MONDAY NIGHT EXCEPT FOR THE HIGHER
ELEVATIONS THEN TEMPS PUSH WELL INTO THE 40S WITH AROUND 50 ALONG
THE LAKESHORES ON TUESDAY WITH A DOWNSLOPE SOUTHEAST FLOW. THE
STRENGTHENING PRESSURE GRADIENT WILL BRING BREEZY TO GUSTY WINDS ON
TUESDAY AFTERNOON WITH HIGHEST GUSTS TO NEAR 40 MPH ALONG THE LAKE
ERIE SHORELINE.

ON CHRISTMAS EVE A PLUME OF MOISTURE WELL ABOVE NORMAL WILL SHIFT
OVER THE MID-ATLANTIC INTO THE NORTHEAST AHEAD OF THE SOUTHERN
STREAM SURFACE LOW AS IT MERGES WITH A NORTHERN STREAM LOW OVER THE
GREAT LAKES. NAEFS PWATS ARE FORECAST TO RISE OVER ONE INCH WHICH IS
NEAR THE 99TH PERCENTILE IN A 30 YEAR PWAT CLIMO. THIS MOISTURE
COMBINED WITH THE STRONG SYNOPTIC FORCING ASSOCIATED WITH THE LOW
AND TEMPERATURES WARMING INTO THE 50S CHRISTMAS EVE SHOULD YIELD
SOME MODERATE TO OCCASIONALLY HEAVY RAIN SHOWERS. THESE SHOWERS MAY
ALSO HELP TO DRAG DOWN SOME GUSTY WINDS ASSOCIATED WITH A 50 KNOT
850MB JET STREAKING OVERHEAD. IN ADDITION TO THE SHOWERS AND
INCREASING WINDS...DOWNSLOPE SOUTHERLY FLOW WILL HELP BOOST SURFACE
TEMPS INTO THE 50S WITH A RUN AT 60 DEGREES FOR BUFFALO AND
ROCHESTER NOT OUT OF THE QUESTION. THESE NUMBERS ARE 20+ DEGREES
ABOVE NORMAL LATE DECEMBER HIGHS.

A SHARP COLD/OCCLUDED FRONT WILL SHIFT ACROSS WESTERN AND
NORTH-CENTRAL NEW YORK WEDNESDAY EVENING AS THE SURFACE LOW TRACKS
ACROSS THE CENTRAL GREAT LAKES. THE TRACK OF THIS LOW IS FAVORABLE
FOR A HIGH WIND EVENT ACROSS WESTERN NEW YORK WITH THE FALLING
PRESSURES WITHIN THE LOW ALSO REQUIRED FOR A HIGH WIND EVENT. WINDS
OF 50-60 KNOTS WILL BE FOUND JUST ABOVE THE SURFACE WITH COLD
ADVECTION BEHIND THE FRONT HELPING TO MIX THESE STRONG WINDS TO THE
SURFACE. CIPS ANALOGS FOR THIS EVENT AND THE SOUTHWEST WINDS ALOFT
LEAN TOWARD MAINLY A WESTERN NEW YORK EVENT POSSIBLY IMPACTING THE
EASTERN LAKE ONTARIO REGION WITH ADVISORY LEVEL GUSTS WELL INLAND
FROM THE LAKES. A BRIEF PERIOD OF GUSTS TO 60 MPH EAST OF LAKE ERIE
BEHIND THE COLD FRONT MAY EVENTUALLY BRING THE NEED FOR A HIGH WIND
WATCH IN FUTURE FORECAST UPDATES.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
A STRONG SURFACE LOW WILL CONTINUE TO DEEPEN NORTH OF THE GREAT
LAKES SHIFTING ACROSS WESTERN QUEBEC THROUGH CHRISTMAS DAY. A TIGHT
PRESSURE GRADIENT WILL REMAIN ACROSS WESTERN AND NORTH-CENTRAL NEW
YORK WHICH WILL ENSURE A GUSTY CHRISTMAS DAY. WINDS GUSTS INTO THE
40S SHOULD MAINTAIN AT LEAST WIND ADVISORY LEVELS THROUGH MUCH OF
THE DAY.

COLD AIR WILL ALSO WORK ACROSS OUR REGION THROUGH THE DAY.
IT IS IMPORTANT TO MENTION THAT WITHOUT A STEEP RIDGE OVER THE
WESTERN STATES THE SOURCE REGION OF THIS COLD AIR WILL BE PACIFIC
BASED AND NOT ARCTIC BASED SO THIS LACK OF AN ARCTIC AIRMASS WILL
BRING A REDUCED THREAT OF ANY SIGNIFICANT SNOW THROUGH CHRISTMAS
DAY. 850MB TEMPS CONTINUE TO LOOK TO ONLY DROP TO BETWEEN -5C AND
-8C. THIS SHOULD ONLY ALLOW SURFACE TEMPS TO SLOWLY FALL INTO THE
MID 30S WITH LOW 30S ACROSS THE HIGHER TERRAIN. THE LATEST FORECAST
CONTINUES TO REFLECT A RAIN/SNOW MIX ACROSS MUCH OF THE FORECAST
AREA WITH SOME LIMITED WET SNOW ACROSS THE HIGHER TERRAIN. SOME WEAK
LAKE ENHANCEMENT IS ALSO POSSIBLE WITH LINGERING POST FRONTAL
MOISTURE AND LAKE INDUCED EQUILIBRIUM LEVELS RISING TO AROUND 5KFT
DURING THE DAY.

BEYOND CHRISTMAS...MODELS CONTINUE TO SHOW A BRIEF PERIOD OF FAIR
WEATHER ON FRIDAY AS SHORTWAVE RIDGING QUICKLY SHIFTS ACROSS THE
LOWER GREAT LAKES. TEMPERATURES SHOULD RECOVER BACK INTO THE MID 40S
AHEAD OF ANOTHER WEAKER GREAT LAKES CUTTER STORM WHICH LOOKS TO
BRING A SHOT OF WESTERN CANADIAN SOURCED AIR ACROSS THE GREAT LAKES.
A CHANCE OF RAIN AND SNOW SHOWERS HAS BEEN INCLUDED FOR SATURDAY
THEN PLAIN SNOW SHOWERS FOR SUNDAY WITH TEMPS BACK TO AROUND
FREEZING.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
TONIGHT LOW LEVEL FLOW WILL BECOME WEAK SOUTHERLY. THIS WILL
CONTINUE TO SUPPORT LOW STRATUS WITH WIDESPREAD MVFR CIGS IN MOST
AREAS. LATE TONIGHT AND MONDAY MORNING SOUTH TO SOUTHEAST FLOW
WILL INCREASE. THE DEVELOPING DOWNSLOPE FLOW SHOULD HELP TO ERODE
THE STRATUS DECK ACROSS LOWER ELEVATIONS WITH CLOUDS SCATTERING
OUT AND CONDITIONS BECOMING VFR. STRATUS MAY LOCK IN LONGER ACROSS
THE HIGHER TERRAIN OF THE SOUTHERN TIER...FINGER LAKES...AND TUG
HILL REGION WHERE MVFR CIGS MAY PERSIST THROUGH MUCH OF MONDAY.

OUTLOOK...
TUESDAY...VFR DETERIORATING TO MVFR/IFR ACROSS HIGHER TERRAIN WITH A
CHANCE OF SHOWERS IN THE AFTERNOON.
WEDNESDAY...MVFR/IFR WITH RAIN AND GUSTY WINDS.
THURSDAY...MVFR WITH A CHANCE OF RAIN/SNOW SHOWERS AND GUSTY WINDS.
FRIDAY...MAINLY VFR.

&&

.MARINE...
HIGH PRESSURE WILL REMAIN OVER QUEBEC THROUGH MONDAY BEFORE DRIFTING
INTO THE CANADIAN MARITIMES BY TUESDAY. SOUTHEAST WINDS WILL BEGIN
TO INCREASE SOME ON MONDAY BUT CONDITIONS WILL REMAIN BELOW SMALL
CRAFT ADVISORY LEVELS UNTIL AT LEAST LATER TUESDAY WHEN SOUTH TO
SOUTHEAST WINDS INCREASE FURTHER.

A DEEP AREA OF LOW PRESSURE IS THEN FORECAST TO LIFT THROUGH THE
CENTRAL GREAT LAKES WEDNESDAY THEN CROSS SOUTHERN QUEBEC ON
THURSDAY. THIS IS A CLIMATOLOGICALLY FAVORED TRACK FOR STRONG WINDS
ON THE LOWER LAKES...WITH A PERIOD OF GALE FORCE WINDS POSSIBLE ON
BOTH LAKES ERIE AND ONTARIO LATE WEDNESDAY NIGHT THROUGH CHRISTMAS
DAY.

&&

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

&&

$$

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






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