Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 141957
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
357 PM EDT MON APR 14 2014

.SYNOPSIS...
A COLD FRONT WILL MOVE EASTWARD ACROSS NY TONIGHT AND BRING A BRIEF
RETURN TO WINTER WEATHER ACROSS THE WESTERN AND CENTRAL PORTIONS OF
THE STATE TUESDAY.  PERIODS OF RAIN TONIGHT MAY BRIEFLY CHANGE OVER
TO A WINTRY MIX BEFORE BECOMING ALL SNOW TUESDAY AND AND TAPERING
OFF WITH SOME ACCUMULATION OVER PRIMARILY HIGHER TERRAIN.  SLOWLY
IMPROVING WEATHER WILL RETURN FOR THE LATTER HALF OF THE WEEK.

&&

.NEAR TERM /THROUGH TUESDAY/...
AN ANOMALOUSLY DEEP LONGWAVE UPPER LEVEL TROUGH OVER THE CENTRAL US
WILL BE THE MAIN FEATURE OF INTEREST THROUGH TUESDAY.  THIS FEATURE
SPORTS TWO EMBEDDED SHORTWAVE PIECES OF ENERGY...ONE NEAR NORTHERN
TX WITH THE OTHER NEAR MN. THE TWO WILL FORCE AN UPPER LEVEL
JET...CURRENTLY RESPONSIBLE FOR THE WIDESPREAD CONVECTION OVER THE
GULF STATES...TO STRENGTHEN AS IT MOVES NORTHEAST OVER SOUTHERN
ONTARIO LATER TONIGHT.  THIS PUTS WESTERN NY UNDER STRONG DIVERGENCE
ALOFT AND FAVORS NEW SURFACE LOW DEVELOPMENT ALONG THE COLD FRONT
THAT WILL BE MOVING EASTWARD ACROSS THE REGION THIS EVENING.
ABUNDANT LIFT AND FRONTOGENETIC FORCING WILL CREATE A STRONG
TEMPERATURE GRADIENT IN THE LOWER ATMOSPHERE...A RIPE SITUATION FOR
MODEL AND FORECAST FAILURE TOWARD DAYBREAK. SEE CHAOS THEORY FOR
DETAILS...

THE INITIAL 12 OR SO HOURS OF THE FORECAST ARE FAIRLY STRAIT
FORWARD...EXPECT SOME PREFRONTAL CONVECTION...ISOLATED THUNDERSTORMS
BUT MOSTLY WIDESPREAD SHOWERS TO MOVE ACROSS THE REGION EARLY THIS
EVENING...FOLLOWED BY A BREAK IN SHOWERS AS THE COLD FRONT MOVES
THROUGH.  /THE INITIAL SHOT OF RAIN HAS COOLED AND STABILIZED THE
AIRMASS ENOUGH IN WESTERN NY TO REMOVE THE THREAT FOR STRONG
GUSTS... SO HAVE REMOVE THE ONGOING WIND ADVISORY./  THEN AS THE
ABOVE MENTIONED JET BEGINS TO MOVE PAST...COLD AIR WILL BEGIN TO
MOVE IN FROM THE WEST AND EVENTUALLY COOL THE NEAR SURFACE TEMPS TO
THE FREEZING MARK TOWARD DAYBREAK OVER FAR WESTERN NY...WITH BELOW
FREEZING TEMPERATURES JUST OFF THE SURFACE BUT STILL WELL ABOVE
FREEZING TEMPERATURES ABOVE THAT.  THIS TEMPERATURE PROFILE SUPPORTS
FREEZING RAIN AND SOME SLEET.  A MAJORITY OF SREF
MEMBERS...INCLUDING THE OPERATIONAL NAM AND GFS PROFILES SUPPORT
THIS SCENARIO...BUT WITH A RAPIDLY EVOLVING WEATHER PATTERN HAVE
LITTLE CONFIDENCE IN ANY OF THE OUTPUT.  HAVE DROPPED THE SURFACE
TEMPERATURES TO THE FREEZING POINT TOWARD DAYBREAK...LOWER THAN ALL
MODEL GUIDANCE EXCEPT THE NAM...AND AM WEARY OF GOING LOWER.  THIS
PUTS THE REGION ON THE EDGE OF A WINTER WEATHER MIX FOR ABOUT 2-4
HOURS BEFORE THE AIR ALOFT FINALLY COOLS AND CHANGES ANY POSSIBLE
MIXED PRECIPITATION OVER TO SNOW FROM WEST TO EAST DURING PRIMARILY
THE MORNING HOURS ON TUESDAY.  FREEZING RAIN WILL BE A POSSIBILITY
BUT CERTAINLY NO GUARANTEE FOR A FEW HOURS THROUGHOUT MUCH OF
WESTERN NY...BUT THIS MAY END UP BEING MORE OF A TECHNICALITY WITH
WARM SURFACES NOT HAVING ENOUGH TIME TO COOL BEFORE A COMPLETE
CHANGEOVER TO SNOW.

FROM AN IMPACT STANDPOINT...THE MORNING COMMUTE MAY OR MAY NOT BE
IMPACTED BY THE MIXED PRECIPITATION...BUT MANY AREA SCHOOLS ARE ON A
SPRING BREAK.  WITH A HIGHLY UNCERTAIN FORECAST...MAY HAVE TO ISSUE
A SHORT FUSED AND SHORT LASTING WINTER WEATHER ADVISORY IF FREEZING
PRECIPITATION DEVELOPS.

SNOW AMOUNTS ARE NOT EXPECTED TO BE MUCH OF AN ISSUE AS THE
SECONDARY LOW MOVES OFF TO THE NORTHEAST AND TAKES ABUNDANT MOISTURE
ALONG WITH IT.  THUS EXPECT MOST LOW ELEVATION AREAS TO SEE SNOW
FLAKES ON TUESDAY BUT WITH LITTLE OR NO LASTING ACCUMULATION...WHILE
HIGHER TERRAIN GETS A SLUSHY 1-3 INCHES.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
A SHARP UPPER LEVEL TROF AXIS FORECAST TO BE ACROSS LAKE ERIE AROUND
00Z WEDNESDAY WILL MOVE RAPIDLY TO THE EAST TUESDAY NIGHT. THIS WILL
USHER IN UNSEASONABLY COLD AIR ALOFT...DROPPING 850 MB TEMPERATURES
DOWN TO AROUND -16C. IN SPITE OF THE CALENDER DATE...THIS IS COLD
ENOUGH TO RESULT IN SOME LAKE INDUCED INSTABILITY...AND IN
COMBINATION WITH THE UPPER LEVEL DISTURBANCE SHOULD BRING SOME LAKE
ENHANCED SNOW SHOWERS TO THE REGION TUESDAY EVENING. FOR THE MOST
PART ACCUMULATIONS SHOULD BE LIGHT...BUT AREAS SE-E OF LAKE ONTARIO
MAY GET A COUPLE INCHES OF SNOW BEFORE DRIER AIR BUILDS IN WITH THE
EXIT OF THE SHORTWAVE LATE TUESDAY NIGHT. RGEM GUIDANCE PROBABLY
CATCHES THIS BEST...BUT SUSPECT GUIDANCE IS UNDERDONE ON SNOW
SHOWERS AND CLOUDS OFF LAKE ERIE SINCE BREAKS IN THE ICE SHOULD
ALLOW FOR SOME MOISTURE ENHANCEMENT. OTHERWISE...TEMPERATURES WILL
BE UNSEASONABLY COLD...EVEN WITH LAKE EFFECT CLOUDS LIMITING
RADIATIONAL COOLING IN SOME AREAS. LOW TEMPERATURES SHOULD BE IN THE
UPPER TEENS TO LOWER 20S WHICH WILL BE NEAR RECORD LOWS FOR THE
DATE. IN BUFFALO...THE RECORD LOW IS 20 AND IN ROCHESTER IT IS 22.

OTHERWISE...HIGH PRESSURE WILL BUILD ACROSS THE REGION
WEDNESDAY...AND THEN SHIFT INTO NEW ENGLAND WEDNESDAY NIGHT. THIS
WILL BRING FAIR WEATHER BUT CONTINUED COLD TEMPERATURES...WITH HIGHS
ON WEDNESDAY ONLY IN THE UPPER 30S TO LOWER 40S. AS THE HIGH SLIDES
FURTHER EAST ON THURSDAY...A SOUTHERLY FLOW WILL BRING IN WARMER AIR
WITH MORE SEASONABLE HIGHS IN THE 50S.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
FOLLOWING THE EXTREMES OF EARLY THIS WEEK...THE LATTER PORTION OF
THE WEEK WILL BE FAIR WITH QUITE SEASONABLE TEMPERATURES. MODEL
GUIDANCE KEEPS IT DRY THROUGH FRIDAY...WITH NEAR NORMAL
TEMPERATURES. AFTER THIS...A CONSENSUS OF THE 12Z GGEM/ECMWF/GFS ARE
A BIT FASTER WITH A CLIPPER LOW WHICH IS NOW FORECAST TO CROSS LATE
FRIDAY NIGHT INTO SATURDAY. THE GGEM IS A MOIST OUTLIER...BUT MOST
GUIDANCE IS FAIRLY WEAK WITH THE SYSTEM SUPPORTING HIGH CHANCE POPS.

AFTER THIS...A FAIRLY ZONAL FLOW BECOMES ESTABLISHED WHICH WILL
BRING SEASONABLE TEMPERATURES AND FREQUENT WEAK SYSTEMS WHICH MAY
BRING SOME LIGHT SHOWERS. CONFIDENCE IN MODEL TIMING WEAK SHORTWAVES
AT THIS TIMEFRAME IS LOW...WITH FORECAST REFLECTING AN EXTENDED
PERIOD OF LOW CHANCE POPS AND MOSTLY CLOUDY SKIES.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
VFR CONDITIONS WILL BE FOUND ACROSS THE REGION THROUGH AT LEAST THE
FIRST HALF OF THIS AFTERNOON...AS A STRENGTHENING STORM SYSTEM
TRACKS NORTHEAST INTO QUEBEC. SFC WINDS ARE GUSTING 40 KNOTS OVER
WESTERN NY THIS AFTERNOON...AND WILL BEGIN TO SUBSIDE AS RAIN
COOLED AIR BEGINS TO MOVE INTO THE REGION.

AS WE PROGRESS THROUGH THE FIRST HALF OF TONIGHT...THE FRONT WILL
EASE ACROSS THE REGION WITH SHOWERS AND POSSIBLY SOME
THUNDERSTORMS. VFR CONDITIONS WILL DETERIORATE TO MVFR...WITH IFR
CIGS EXPECTED AFTER 06Z TUESDAY. ANY RAIN WILL CHANGE OVER TO SNOW
AFTER 12Z FROM WEST TO EAST...WITH A BRIEF WINTRY MIX POSSIBLE
WEST OF THE GENESEE VALLEY.

OUTLOOK...
TUESDAY NIGHT...MVFR/IFR WITH RAIN SNOW SHOWERS DIMINISHING.
WEDNESDAY THROUGH FRIDAY...VFR.
SATURDAY...MVFR WITH SHOWERS.

&&

.MARINE...
A STRENGTHENING STORM SYSTEM OVER LAKE HURON WILL MOVE NORTHEAST
TOWARD WESTERN QUEBEC BY THIS EVENING. THIS WILL PRODUCE A STRONG
SOUTHERLY GRADIENT ACROSS THE LOWER GREAT LAKES THROUGH THE FIRST
HALF OF TONIGHT WITH WINDS REACHING SMALL CRAFT ADVISORY CRITERIA
FOR NEARSHORE WATERS AS WELL AS FOR THE IAG AND ST LAWRENCE
RIVERS. BECAUSE OF THE SOUTHERLY FLOW... WAVES SHOULD NOT BE AN
ISSUE...BUT EVEN SO...A STABILIZING DOME OF CHILLY AIR OVER THE
CENTER OF THE LAKE WILL KEEP WINDS AND WAVES IN THE OPEN WATERS TO
A MINIMUM.

THE WINDS OVER THE NEARSHORE WATERS WILL SUBSIDE LATER TONIGHT WHEN
A SLOW MOVING FRONTAL BOUNDARY WILL PUSH THROUGH. IN THE WAKE OF THE
FRONT...WINDS AND WAVES WILL BUILD WITHIN A COLD ADVECTIVE NORTHWEST
FLOW DURING THE DAY TUESDAY. THIS MAY LEAD TO ANOTHER ROUND OF SMALL
CRAFT ADVISORIES AT THAT TIME.

HIGH PRESSURE IS THEN FORECAST TO MOVE OVERHEAD WEDNESDAY USHERING
IN A PERIOD OF TRANQUIL CONDITIONS ON THE LAKE FOR THE REMAINDER OF
THE WEEK.

&&

.HYDROLOGY...
CONCERNS CONTINUE FOR PORTIONS OF THE EASTERN LAKE ONTARIO
REGION. THERE IS STILL A SIGNIFICANT SNOW PACK ON THE TUG
HILL...HOWEVER THIS HAS BEEN AND WILL CONTINUE TO MELT INTO RUN
OFF RAPIDLY THROUGH EARLY TONIGHT. SMALLER CREEKS FED BY THE TUG
HILL AND HIGHER TERRAIN OF THE ADIRONDACKS WILL CONTINUE TO FLOW
NEAR BANKFULL DURING THIS PERIOD. TONIGHT AND TUESDAY...UP TO AN
INCH OF RAIN IS EXPECTED IN THE EASTERN LAKE ONTARIO REGION. THIS
WILL CAUSE BOTH CREEKS AND MAIN STEM RIVERS TO RISE.

THE BLACK RIVER IS ALREADY AT FLOOD STAGE AT WATERTOWN. SNOW
MELT WILL PUSH THIS GRADUALLY HIGHER...WITH MORE SIGNIFICANT RISES
LIKELY FOLLOWING RAINS ON TONIGHT AND TUESDAY. THIS IS LIKELY
TO PRODUCE MINOR FLOODING ON THE BLACK RIVER FROM LOWVILLE TO
WATERTOWN. THE RIVER IS LIKELY TO REMAIN ABOVE FLOOD STAGE FOR AN
EXTENDED PERIOD OF TIME...PROBABLY UNTIL THURSDAY OR FRIDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...FLOOD WATCH THROUGH LATE WEDNESDAY NIGHT FOR NYZ006>008.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LEZ020-
         040-041.
         SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR
         LOZ030.
         SMALL CRAFT ADVISORY UNTIL 2 AM EDT TUESDAY FOR LOZ043>045.
         SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR
         LOZ042.
         SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR
         SLZ022-024.

&&

$$

SYNOPSIS...ZAFF
NEAR TERM...ZAFF
SHORT TERM...APFFEL
LONG TERM...APFFEL
AVIATION...ZAFF
MARINE...APFFEL/ZAFF
HYDROLOGY...HITCHCOCK/APFFEL







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