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Area Forecast Discussion
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000
FXUS61 KBUF 210949
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
449 AM EST FRI NOV 21 2014

.SYNOPSIS...
LAKE EFFECT SNOWS WILL WEAKEN LATER THIS AFTERNOON AS HIGH PRESSURE 
PASSES BY TO THE SOUTH OF OUR NEW YORK. MUCH WARMER AIR WILL ARRIVE 
OVER THE WEEKEND AND INTO EARLY NEXT WEEK ALONG WITH RAIN SHOWERS AT 
TIMES...POTENTIALLY BRINGING A FLOOD RISK TO AREAS WHICH WERE BURIED 
BY LAKE EFFECT SNOW. TEMPERATURES WILL THEN TURN COLDER AGAIN FOR 
THE SECOND HALF OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE SURFACE PATTERN THIS MORNING SHOWS BROAD HIGH PRESSURE CENTERED 
OVER THE MIDWEST AND EXPANDED ACROSS THE OHIO VALLEY, MID-ATLANTIC 
AND SOUTHEAST STATES WITH A WEAK SURFACE TROUGH CROSSING THE LOWER 
GREAT LAKES. COLD AIR UNDER A VEERING NORTHWEST FLOW REMAINS IN 
PLACE WITH 850MB TEMPS OF -15C. THIS IS CONTINUING TO PROVIDE WELL 
BELOW NORMAL SURFACE TEMPERATURES AND EXTREME LAKE INDUCED INSTABILITY 
WHICH HAS SUPPORTED THE LAKE EFFECT SNOW BANDS BUT THE SURFACE 
TROUGH CROSSING OUR REGION IS ACTING TO DISRUPT THE INTENSITY OF THE 
SNOW BANDS WITH SOME SHEER. THE BETTER FETCH ACROSS LAKE ONTARIO IS 
HELPING THE LAKE ONTARIO BAND TO BE BETTER ORGANIZED THAN THE LAKE 
ERIE BAND WHICH HAS NEARLY DISSIPATED. THE SURFACE TROUGH IS ALSO 
KICKING OF SOME SCATTERED LIGHT SNOW SHOWERS AS IT SHIFTS SOUTHEAST 
ACROSS WESTERN AND CENTRAL NEW YORK.

OFF LAKE ERIE...THROUGH TODAY EXPECT THE LAKE EFFECT SNOW TO REMAIN 
VERY WEAK IF NOT FULLY DISSIPATED BY MIDDAY. LAKE EFFECT HEADLINES 
ACROSS THE SOUTHERN TIER WILL LIKELY BE CANCELED WITH THE NEXT 
UPDATE IF THE IDEA CONTINUES ON TRACK. CURRENT RADAR PRESENTATION IS 
NOT MUCH TO SPEAK OF BUT AFTER THE SURFACE TROUGH PASSES THE BAND 
MAY TRY TO REORGANIZE WITHIN THE EXTREME LAKE INDUCED INSTABILITY. 
WINDS ARE EXPECTED TO BACK BEHIND THE SURFACE TROUGH WHICH MAY LIFT 
ANY REMNANT LAKE BAND TO THE NORTH WITH NOT MUCH NEW ACCUMULATION.

OFF LAKE ONTARIO...THE BETTER ORGANIZED LAKE BAND SOUTHEAST OF THE 
LAKE WILL PRESS FURTHER SOUTH AND MAY BECOME MULTIBAND IN NATURE 
FROM ROCHESTER TO FAIR HAVEN. LAKE EFFECT SHOULD HOLD HERE THROUGH 
THE MORNING WITH 3-6 INCH ACCUMULATIONS IN THE LAKE EFFECT ADVISORY 
AREAS. THE WARNING FOR LEWIS COUNTY HAS BEEN CANCELLED WITH THE 
OSWEGO COUNTY WARNING CONTINUING AS THE LAKE SNOWS WILL SHIFT BACK
NORTH WITH BACKING WINDS LATER TODAY. THIS MAY BRING AN ADDITIONAL 
FEW INCHES DEPENDING ON HOW LONG THE BAND REMAINS ORGANIZED FOR. 
LAKE INDUCED EQUILIBRIUM LEVELS 10-15 KFT WILL LOWER BELOW 5KFT 
OVERNIGHT WHICH WILL BRING AN END TO LAKE EFFECT OVERNIGHT.

OUTSIDE OF THE LAKE EFFECT EXPECT MAINLY SUNNY SKIES TODAY AND 
MAINLY CLEAR TONIGHT. HIGH TEMPS WILL ONLY RISE INTO THE LOW TO MID 
20S THEN FALLING BACK INTO THE TEENS TONIGHT.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
THE FOCUS FOR THIS PERIOD REMAINS THE POTENTIAL FOR SIGNIFICANT 
WIDESPREAD FLOODING...AS MUCH WARMER TEMPERATURES AND RAINFALL PUSH 
INTO THE REGION. 

THE WATER STORED IN THE RECENTLY FALLEN LAKE EFFECT SNOW IS LIKELY 
TO BE AT LEAST SEVERAL INCHES. AT THIS TIME...IT APPEARS THAT THE 
GREATEST CONCERN FOR FLOODING WILL BE IN THE SUNDAY NIGHT THROUGH 
TUESDAY TIME FRAME. SUNDAY NIGHT WILL REMAIN MILD WITH LOWS 
REMAINING WELL ABOVE FREEZING. BY MONDAY...SURFACE TEMPERATURES WILL 
BE CLIMBING TOWARDS 60 DEGREES WHICH WITH DEWPOINTS IN THE MID TO 
UPPER 40S AND SOUTHERLY WINDS SHOULD ALLOW FOR MUCH IF NOT ALL OF 
THE SNOWPACK TO MELT. 

THE HIGH LIQUID IN THE SNOWPACK COMBINED THE FALLING RAINFALL WILL 
LIKELY LEAD TO FLOODING...BOTH URBAN AND AREAL AS WELL AS 
SIGNIFICANT RISES ON LOCAL STREAM/CREEKS AND RIVERS. IT IS DIFFICULT 
TO SAY AT THIS POINT HOW SIGNIFICANT THE FLOODING WILL BE WITH THE 
EXACT AMOUNT OF WATER STORED IN THE SNOWPACK STILL AN UNKNOWN. ONCE
THIS IS ANSWERED...A BETTER IDEA OF THE SEVERITY OF THE FLOODING 
WILL BE BETTER KNOWN.  

HIGH PRESSURE WILL BE CENTERED OVER THE CAROLINAS SATURDAY MORNING. 
THE RETURN FLOW AROUND THE HIGH WILL BE ADVECTIING THE LEADING EDGE 
OF A WARMER AIRMASS INTO THE REGION ON AN INCREASING SOUTHWESTERLY 
FLOW AS 850 MB TEMPERATURES GO ABOVE FREEZING. INITIALLY THIS COULD 
BE PROBLEMATIC WITH THE LOW LEVEL ARCTIC AIRMASS STILL ENTRENCHED 
ACROSS THE REGION WITH A STRONG INVERSION LIKELY IN PLACE SATURDAY 
MORNING. AS THE SHORTWAVE OVER THE INTERMOUNTAIN WEST EJECTS OUT 
OVER THE GREAT LAKES...ISENTROPIC ASCENT AND A SHOT OF PV ADVECTION 
SATURDAY WILL SUPPORT A PERIOD OF RAIN DEVELOPING FROM WEST TO EAST. 
LATEST PROFILES WOULD SUGGEST THIS FALLS AS MAINLY LIGHT RAIN. 
HOWEVER...THERE COULD STILL BE SOME POCKETS OF BELOW FREEZING 
TEMPERATURES AT THE SURFACE WHICH MAY PRODUCE SOME PATCHY FREEZING 
RAIN AT THE ONSET...ESPECIALLY ACROSS THE HILLS SOUTH OF BUFFALO AND 
ROCHESTER...AND ALSO VALLEYS TO THE EAST OF LAKE ONTARIO. SHARP 
WARMING ALOFT WILL LIMIT MAINTENANCE FOR SUB-ZERO WET BULBING SO 
THINK ANY ICING THREAT WILL BE LIMITED...BUT WILL STILL NEED TO BE 
MONITORED. 

THE WARMING TREND WILL BEGIN SATURDAY WITH DAYTIME HIGHS IN THE MID 
TO UPPER 30S OR MUCH OF THE AREA WITH TEMPERATURES NEAR 40 ALONG THE 
LAKE ERIE SHORE AND NIAGARA FRONTIER. ALTHOUGH THIS WILL CAUSE SOME 
MELTING OF THE DEEP SNOWPACK IN PLACE EAST OF THE LAKE ERIE... 
FLOODING CONCERNS AT THIS TIME LOOK MINIMAL AS THE SNOWPACK WILL 
ABSORB THIS MELT. 

WEAK ISENTROPIC ASCENT WILL THEN BE ONGOING THROUGH THE DAY SATURDAY 
NIGHT INTO EARLY SUNDAY...AS A 100 KNOT JET DEVELOPS OVERHEAD IN 
RESPONSE TO THE DEEPENING LONGWAVE TROUGH UPSTREAM. THIS WILL HELP 
ORIENT A MID-LEVEL BAROCLINIC ZONE ACROSS THE AREA WHICH WILL SERVE 
AS A FOCUS FOR ONGOING LIGHT PRECIPITATION DURING THIS PERIOD. 

TEMPERATURE RECOVERY WILL CONTINUE SATURDAY NIGHT WITH AN INCREASING 
SOUTHERLY LOW LEVEL FLOW AND WARM AIR ADVECTION LIKELY KEEPING 
OVERNIGHT TEMPERATURES ABOVE FREEZING. DEWPOINT TEMPERATURES LOOK TO 
ALSO GO ABOVE FREEZING. THIS COMBINED WITH ADDITIONAL RAIN...ALBEIT 
LIGHT WILL LEAD TO FURTHER RIPENING OF THE DEEP SNOW PACK. 

THIS LIFT WILL EXIT THE REGION LATE SUNDAY AS RIDGING DEVELOPS 
NORTHWARD INTO THE REGION. THIS WILL END THE THREAT OF PRECIPITATION 
FOR A SHORT TIME...ALTHOUGH LINGERING LOW LEVEL MOISTURE MAY KEEP 
CLOUD COVER IN PLACE. DEEP LAYER SOUTHERLY FLOW WILL CONTINUE TO 
ADVECT WARMER AIR INTO THE REGION. AFTERNOON TEMPERATURES NEARING 50 
DEGREES WITH DEWPOINTS CONTINUING TO RISE INTO THE MID TO UPPER 30S. 
THE COMBINATION OF WARMING TEMPERATURES...INCREASE SOUTHERLY WINDS 
AND RISING DEWPOINTS SHOULD ALLOW FOR THE DEEP SNOWPACK EAST OF BOTH 
GREAT LAKES TO CONTINUE TO COMPACT AND DIMINISH IN HEIGHT. 

SHORTWAVE EJECTS NORTHEAST FROM THE CENTRAL APPALACHIANS SUNDAY 
LIFTING ACROSS THE AREA SUNDAY NIGHT. THE MAIN BRUNT OF DYNAMICS... 
MOISTURE AND RAIN WILL QUICKLY SPREADS ACROSS THE REGION SUNDAY 
EVENING. DIFFLUENCE ALOFT AND THE LIFTING SHORTWAVE WILL PROVIDE 
DYNAMIC FORCING FOR ASCENT OVER THE REGION. ISENTROPIC ASCENT 
COMMENCES AS THE WARM FRONT LIFTS INTO THE REGION SUNDAY NIGHT.
PER LATEST GEFS...PRECIPITABLE WATER VALUES FORECAST +2 TO +3 
STANDARD DEVIATION AS VALUES INCREASE TO NEAR 1.25 INCHES. PROFILES 
INDICATE A DEEPLY SATURATED COLUMN WHICH DOES GIVE AT LEAST SOME 
POTENTIAL FOR LOCALLY HEAVY RAIN. HOWEVER..IT DOES APPEAR THAT THIS 
WILL BE A RATHER QUICK SHOT OF PRECIPITATION WITH MOST OF THE RAIN
OUT OF THE AREA BY MONDAY MORNING...AS A DRY SLOT PUNCHES INTO THE 
REGION IN WAKE OF THE WARM FRONT. WILL MAINTAIN RAINFALL AMOUNTS 
DURING THIS PERIOD IN THE ONE QUARTER TO ONE THIRD OF AN INCH RANGE. 

THE BASE OF THE UPPER LEVEL TROUGH AND ITS COLD AIR WILL REMAIN JUST 
TO OUR WEST THROUGH THE COURSE OF MONDAY NIGHT. THIS WILL ALLOW FOR 
SURFACE TEMPERATURES TO REMAIN ABOVE FREEZING THROUGH THE NIGHT AND 
ALLOW FOR SNOWPACK MELTING TO CONTINUE. WITH THE TROUGH NEARBY WILL 
CARRY A LOW CHANCE POP FOR A PASSING SHOWER.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
FOR THE TUESDAY THROUGH THURSDAY TIME PERIOD COOLING TEMPERATURES 
WILL END THE THREAT OF FLOODING...BUT AGAIN RENEW THE LAKE EFFECT 
SNOW POTENTIAL. 

ON TUESDAY AN AMPLIFIED UPPER AIR PATTERN WILL CONTINUE AS A LONG 
WAVE TROUGH WILL BE FOUND OVER THE GREAT LAKES REGION AND DOWN 
TOWARDS THE SOUTHERN MISSISSIPPI VALLEY. THIS TROUGH WILL SPLIT THE 
RIDGE TO OUR EAST (PRIOR WARM AIRMASS) AND RIDGE ACROSS THE WEST. 

WITH SHORTWAVES PASSING THROUGH THIS UPPER LEVEL TROUGH...AND WITH 
THIS TROUGH NOW NEARING OUR REGION WILL MAINTAIN LOW CHANCE POPS FOR 
A MIX OF RAIN AND SNOW. AS THE COLD AIR DEEPENS THROUGH THE 
DAY...LAKE EFFECT SNOW WILL AGAIN BECOME A CONCERN. 

BY TUESDAY NIGHT TEMPERATURES ALOFT AT 850 HPA WILL HAVE DROPPED TO 
NEAR -10C...AND FALLING. ALOFT THIS UPPER LEVEL LOW TO OUR WEST WILL 
NOT BE AS DEEP AS THIS CURRENT WEEK OF LAKE EFFECT SNOW...COLD AIR 
NOT AS DEEP AND CAPPING INVERSION HEIGHTS NOT AS TALL. THAT SAID 
PARAMETERS ARE STILL LOOKING FAVORABLE FOR ANOTHER BAND OF LAKE 
EFFECT SNOW STARTING TUESDAY PM ACROSS AREAS NORTHEAST OF THE 
LAKES...THEN DROPPING SOUTHWARD THROUGH TUESDAY NIGHT AND WEDNESDAY. 
WITH THE COLD AIR NOT AS DEEP THERE MAY EVEN BE A LITTLE RAIN MIXED 
IN WITH THE BANDS OF SNOW DURING THE DAY WEDNESDAY. 

A SHORTWAVE WILL CROSS THE EASTERN GREAT LAKES WEDNESDAY/WEDNESDAY 
NIGHT...WHICH MAY DISRUPT THE BANDS SOME...BEFORE A WESTERLY WIND 
CARRIES THE LAKE EFFECT SNOW INLAND TO AREAS EAST OF THE LAKES...AND 
SOUTH OF BUFFALO/WATERTOWN FOR WEDNESDAY NIGHT. 

BANDS OF LAKE EFFECT SNOW WILL FADE EARLY THURSDAY AS WE GET A 
LITTLE WARM AIR ADVECTION ALOFT AHEAD OF AN APPROACHING SHORTWAVE. 
THIS SHORTWAVE MAY BRING SOME LIGHT GENERAL SNOW TO WNY BY LATE IN 
THE DAY THURSDAY.

&&

.AVIATION /10Z FRIDAY THROUGH TUESDAY/...
OUTSIDE OF LAKE EFFECT AREAS CONDITIONS A SURFACE TROUGH CROSSING 
THE REGION IS KICKING OFF SOME BRIEF SCATTERED SNOW SHOWERS WITH 
TEMPO MVFR/IFR POSSIBLE. OTHERWISE VFR EXPECTED THROUGH THE PERIOD
AS HIGH PRESSURE MOVES ACROSS THE REGION.   

AS FOR LAKE EFFECT...THE LAKE SNOWS OFF LAKE ERIE HAVE RAPIDLY 
BROKEN UP WITH A SURFACE TROUGH CROSSING WESTERN NEW YORK. EXPECT 
MAINLY VFR THROUGH THE REST OF THE PERIOD UNLESS THE BAND TRIES TO 
RE-ORGANIZE LATER THIS MORNING WHICH IS UNLIKELY AS SURFACE RIDING 
BUILDS ACROSS THE AREA.

OFF LAKE ONTARIO... A PLUME OF SNOW EXTENDS ACROSS THE SOUTHEAST 
LAKE SHORE. THIS BAND WILL SETTLE TO THE SOUTH AND BECOME MULTI BAND 
IN NATURE THIS MORNING FROM ROCHESTER TO OSWEGO. THIS WILL KEEP VFR 
AT KART...BUT POSSIBLE MVFR/IFR COULD OCCUR AT KROC WITH LAKE EFFECT 
DROPPING TOWARD THE TERMINAL.

BOTH AREAS OF LAKE EFFECT WILL LIFT BACK NORTH AND RAPIDLY WEAKEN 
FRIDAY EVENING AS SURFACE RIDGING LOWERS INVERSION HEIGHTS. 

OUTLOOK...
SATURDAY...VFR. 
SATURDAY NIGHT THROUGH MONDAY...PERIODS OF IFR/MVFR IN RAIN. LLWS 
POSSIBLE SUNDAY NIGHT AND INTO MONDAY MORNING.
TUESDAY...MAINLY VFR WITH A CHANCE OF RAIN/SNOW SHOWERS.

&&

.MARINE...
SMALL CRAFT ADVISORIES IN PLACE FOR THE NEARSHORE WATERS. HIGH 
PRESSURE WILL BUILD ACROSS THE GREAT LAKES REGION TODAY AND WEAKEN 
THE INFLUENCING SFC PRESSURE GRADIENT. WINDS WILL FIRST RELAX 
THROUGH TODAY BUT WAVES LOOK TO REMAIN ELEVATED INTO THE EVENING 
WHERE ADVISORIES THEN EXPIRE. 

ANOTHER STORM SYSTEM WILL LIFT NORTH OUT OF THE LOWER MISSISSIPPI 
RIVER VALLEY SUNDAY TO MICHIGAN BY SUNDAY NIGHT. THIS DEEPENING 
STORM SYSTEM WILL BRING SOME ELEVATED WINDS WITH POSSIBLE GALES ON 
LAKE ERIE AND ADVISORIES POSSIBLE ON LAKE ONTARIO BY MONDAY.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WARNING UNTIL 6 PM EST THIS EVENING FOR 
     NYZ006.
     LAKE EFFECT SNOW ADVISORY UNTIL 6 PM EST THIS EVENING FOR 
     NYZ004-005.
     FLOOD WATCH FROM SUNDAY AFTERNOON THROUGH WEDNESDAY MORNING 
     FOR NYZ010>012-085.
     LAKE EFFECT SNOW WARNING UNTIL NOON EST TODAY FOR NYZ019-020.
     LAKE EFFECT SNOW ADVISORY UNTIL NOON EST TODAY FOR NYZ021.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR LEZ040-
         041.
         SMALL CRAFT ADVISORY UNTIL 4 AM EST SATURDAY FOR 
         LOZ043>045.
         SMALL CRAFT ADVISORY UNTIL 9 AM EST THIS MORNING FOR 
         LOZ042.

&&

$$

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







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