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Area Forecast Discussion
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000
FXUS61 KBUF 121422
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1022 AM EDT THU MAR 12 2015

.SYNOPSIS...
HIGH PRESSURE DRAPED FROM NORTHERN ONTARIO PROVINCE TO THE CENTRAL 
GREAT LAKES WILL SLOWLY BUILD EASTWARD TO NEW ENGLAND TODAY AND 
FRIDAY...WHILE BRINGING TRANQUIL WEATHER TO WESTERN AND NORTH 
CENTRAL NEW YORK. THE HIGH WILL THEN MOVE OFF THE ATLANTIC COASTLINE 
FRIDAY NIGHT AND SATURDAY...ALLOWING COMPLEX LOW PRESSURE TO PUSH 
ACROSS THE REGION DURING THE UPCOMING WEEKEND. THIS SYSTEM WILL 
BRING SOME RAIN TO OUR REGION...WHICH MAY BE MIXED WITH SOME SNOW AS 
IT BEGINS AND ENDS.

&&

.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE OVER EASTERN ONTARIO CANADA THIS MORNING WILL CONTINUE 
TO ADVANCE EASTWARD ACROSS SOUTHERN CANADA TODAY...AND SETTLE 
TOWARDS EASTERN NEW YORK AND WESTERN NEW ENGLAND BY FRIDAY MORNING. 
THIS FEATURE WILL PROVIDE WESTERN AND NORTHERN CENTRAL NEW YORK WITH 
FAIR AND TRANQUIL WEATHER...ALBEIT WITH SOME INCREASE IN MID AND 
HIGH CLOUDS THIS AFTERNOON AND EVENING AS WEAK WARM AIR ADVECTION 
DEVELOPS ALOFT. 

WITH RESPECT TO TEMPERATURES...A BRIEF SHOT OF COLDER AIR 
ACCOMPANYING THE INCOMING HIGH WILL RESULT IN A BRIEF RETURN TO 
BELOW NORMAL TEMPERATURES TODAY...WITH 925 MB TEMPS FROM THE NAM AND 
GFS SUGGESTING THAT HIGHS SHOULD RANGE FROM AROUND 30 ACROSS THE 
NORTH COUNTRY TO THE MID TO UPPER 30S SOUTH OF LAKE ONTARIO. THESE 
TEMPERATURES WILL THEN BE FOLLOWED BY NIGHTTIME LOWS RANGING FROM 10 
TO 15 EAST OF LAKE ONTARIO...TO THE LOWER AND MID 20S ACROSS FAR 
WESTERN NEW YORK TONIGHT.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
A SPLIT FLOW WILL BE FOUND ACROSS THE COUNTRY DURING THIS PERIOD... 
WITH THE GREAT LAKES REGION BEING UNDER THE INFLUENCE OF A LOW 
AMPLITUDE...PACIFIC AIR DOMINATED NORTHERN BRANCH. THIS WILL SUPPORT 
ABOVE NORMAL TEMPERATURES ACROSS OUR REGION THROUGH MUCH OF THE 
UPCOMING WEEKEND. WHILE THE MILD WEATHER WILL CONTINUE TO WHITTLE 
AWAY AT THE REGIONS DEEP SNOWPACK...A RAINY STORM SYSTEM ON SATURDAY 
WILL INTRODUCE AT LEAST THE RISK FOR SOME FLOODING. MORE ON THIS 
CONCERN CAN BE FOUND WITHIN THE HYDROLOGY SECTION BELOW.

THIS PERIOD WILL OPEN WITH NICE WEATHER ON FRIDAY AS HIGH PRESSURE 
OVER NEW ENGLAND WILL GRUDGINGLY PUSH EAST TO THE COAST. WHILE MOST 
OF THE REGION WILL EXPERIENCE AT LEAST PARTIAL SUNSHINE...A 
DEEPENING SOUTHERLY FLOW BETWEEN THE EXITING HIGH AND AN INVERTED 
TROUGH OVER THE MISSISSIPPI VALLEY WILL ADVECT THICKENING HIGH LEVEL 
CLOUDS ACROSS THE LOWER GREAT LAKES DURING THE COURSE OF THE 
AFTERNOON. IT WILL ALSO SUPPORT WARMER WEATHER AS H85 TEMPS WILL 
CLIMB ABOVE ZERO C. THIS WILL TRANSLATE INTO MAX TEMPS THAT WILL 
RANGE FROM 45 TO 50F ACROSS THE WRN COUNTIES TO READINGS WITHIN A 
FEW DEGREES OF 40 ACROSS THE NORTH COUNTRY. WHILE THESE TEMPS WILL 
CERTAINLY MELT OFF SOME OF OUR SNOWPACK...DEW POINTS AT OR BELOW 32 
FOR THE VAST MAJORITY OF THE REGION WILL KEEP US FROM EXPERIENCING A 
SIGNIFICANT RELEASE OF WATER. SO FAR...SO GOOD.

CONDITIONS WILL RAPIDLY DETERIORATE FRIDAY NIGHT AS THE INVERTED SFC 
TROUGH WILL PUSH EAST ACROSS THE GREAT LAKES AND OHIO VALLEY. WARM 
ADVECTION AHEAD OF THE TROUGH WILL HELP TO GENERATE MAINLY LIGHT 
PRECIPITATION ACROSS MUCH OF OUR FORECAST AREA...ALTHOUGH A QUARTER 
TO AS MUCH AS A HALF INCH OF RAIN WILL BE POSSIBLE OVER THE SOUTHERN 
TIER AND FINGER LAKES. A ROBUST NORTHERN BRANCH SHORTWAVE TRACKING  
SOUTHEAST ACROSS THE UPPER GREAT LAKES WILL HELP TO SUPPRESS 
RELATIVELY DEEP SOUTHERN STREAM MOISTURE FROM MOVING UP OVER OUR 
FORECAST AREA...AS THE VARIOUS GUIDANCE PACKAGES ARE IN STRONG 
AGREEMENT THAT PWAT VALUES OF AN INCH OR MORE WILL BE CONCENTRATED 
OVER SOUTHERN PARTS OF OHIO AND PENNSYLVANIA. FOR WHAT ITS WORTH... 
THE STRONGEST LIFT WILL ALSO BE TO OUR SOUTH AS THE JET ENTRANCE 
REGION OF A CYCLONIC CURVED 140KT H25 WILL ALSO PASS ACROSS THE 
KEYSTONE STATE. THE CONTINUED WARM ADVECTION AHEAD OF THE SFC TROUGH 
WILL VIRTUALLY GUARANTEE THAT THE PCPN WILL FALL AS RAIN OVER THE 
WESTERN COUNTIES...WITH A MIX OF RAIN AND SNOW POSSIBLE EAST OF LAKE 
ONTARIO. 

ON SATURDAY...THE AFOREMENTIONED NORTHERN BRANCH SHORTWAVE WILL PLOW 
ACROSS SOUTHERN ONTARIO WHILE A BROAD DISORGANIZED SFC REFLECTION 
WILL PASS DIRECTLY ACROSS OUR FORECAST AREA. THIS WILL LEAD TO THE 
LIKELIHOOD OF AN ADDITIONAL COUPLE TENTHS OF AN INCH OF RAIN ACROSS 
OUR REGION...WITH TEMPERATURES GENERALLY IN THE 40S. AGAIN...THE 
DEEPEST MOISTURE FIELD WILL STAY TO OUR SOUTH AND EAST...BUT EVEN 
THIS AMOUNT OF RAIN COUPLED WITH CONTINUED MELTING OF OUR SNOWPACK 
COULD PRODUCE SIGNIFICANT RISES ON AREA TRIBUTARIES. LATER SHIFTS 
MAY NEED TO CONSIDER A FLOOD WATCH FOR PORTIONS OF THE SOUTHERN TIER 
IF THE AXIS OF HEAVIER RAIN SHIFTS FARTHER TO THE NORTH. PLEASE 
REFER TO THE HYDROLOGY SECTION BELOW FOR DETAILS. 

AS THE SHORTWAVE CROSSES LAKE ONTARIO AND THE ADIRONDACKS SATURDAY 
NIGHT...STRONG COLD ADVECTION IN ITS WAKE WILL CHANGE THE RAIN 
SHOWERS OVER TO SNOW SHOWERS. SNOW ACCUMULATIONS SHOULD BE 
INSIGNIFICANT DURING THE OVERNIGHT...ALTHOUGH AN INCH OR TWO WILL 
NOT BE OUT OF THE QUESTION EAST OF LAKE ONTARIO.

ON SUNDAY...A NEWLY FORMED DEEP CLOSED LOW IS FORECAST TO MOVE FROM 
NEW ENGLAND TO NOVA SCOTIA WHILE A SHORTWAVE RIDGE WILL BUILD ACROSS 
THE UPPER GREAT LAKES. THIS WILL LEAVE A MOIST CYCLONIC FLOW OVER 
WESTERN AND NORTH CENTRAL NEW YORK WITH RESIDUAL SNOW SHOWER 
ACTIVITY DIMINISHING DURING THE COURSE OF THE DAY. GIVEN H85 TEMPS 
OF -4 TO -6C...MAX TEMPS WILL ONLY TOP OUT IN THE 30S F.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
RIDGING WILL BUILD ACROSS THE LOWER GREAT LAKES ON MONDAY. THIS WILL 
PROVIDE A FAIR AMOUNT OF SUNSHINE FOR THE REGION WITH TEMPERATURES 
CLIMBING WELL INTO THE 40S. 

THE MEDIUM RANGE ENSEMBLES THEN DIFFER ON THE HANDLING OF THE NEXT 
COLD FRONT...WITH THE ECMWF FAVORING A MONDAY NIGHT PASSAGE WHILE 
THE GFS BASED GEFS SUGGESTS THE EVENT WILL HOLD OFF UNTIL TUESDAY. 
WILL LEAN MORE TOWARDS THE ECMWF WITH HIGHER POPS MONDAY NIGHT FOR 
SNOW SHOWERS.

SFC HIGH PRESSURE WILL THEN BUILD ACROSS THE OHIO VALLEY LATER 
TUESDAY INTO WEDNESDAY WITH A MARGINALLY COLD WEST TO NORTHWEST FLOW 
POSSIBLY SUPPORTING SOME LAKE SNOW SHOWERS SOUTHEAST OF LAKE 
ONTARIO.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
HIGH PRESSURE RIDGED FROM NORTHERN ONTARIO TO THE CENTRAL GREAT 
LAKES WILL GRADUALLY BUILD SOUTHEASTWARD ACROSS NEW YORK STATE AND 
INTO NEW ENGLAND TODAY AND TONIGHT. THIS WILL PROVIDE OUR REGION 
WITH FAIR WEATHER AND VFR CONDITIONS...WITH JUST SOME INCREASE IN 
MID AND HIGH CLOUDS EXPECTED THIS AFTERNOON AND EVENING AS WARM AIR 
ADVECTION DEVELOPS ALOFT. 

OUTLOOK... 
FRIDAY...VFR. 
FRIDAY NIGHT...DETERIORATION TO MVFR. RAIN DEVELOPING SOUTH OF LAKE 
ONTARIO...WITH A CHANCE OF RAIN AND SNOW ACROSS THE NORTH COUNTRY. 
SATURDAY...MVFR IN RAIN...WHICH MAY BE MIXED WITH SNOW ACROSS THE 
NORTH COUNTRY IN THE MORNING.
SATURDAY NIGHT...MVFR/IFR WITH SCATTERED TO NUMEROUS RAIN AND SNOW 
SHOWERS. 
SUNDAY...IFR WITH MORNING SNOW SHOWERS LIKELY ACROSS EASTERN 
SECTIONS...OTHERWISE MVFR WITH A CHANCE OF SNOW SHOWERS. 
SUNDAY NIGHT AND MONDAY...MAINLY VFR.

&&

.MARINE...
HIGH PRESSURE WILL ADVANCE FROM THE WESTERN GREAT LAKES TO THE 
CENTRAL GREAT LAKES OVERNIGHT. A SOMEWHAT STRONG PRESSURE GRADIENT
BETWEEN THIS HIGH...AND A WEAK SURFACE TROUGH THAT WILL LIE JUST
TO THE NORTH OF LAKE ONTARIO WILL CREATE BRISK WESTERLY WINDS UP
TO 15 KNOTS OR SO. THESE WINDS WILL ALSO YIELD 3 TO 4 FOOT WAVES
ON THE LAKE WATERS. AS THE AREA OF HIGH PRESSURE CROSSES THE
REGION TOMORROW EXPECT TRANQUIL CONDITIONS ON THE LAKES.

&&

.HYDROLOGY...
SNOW WILL CONTINUE TO MELT GRADUALLY THROUGH FRIDAY WITH NO
FLOODING EXPECTED THROUGH THE END OF THE WEEK. WHILE TEMPERATURES
WILL RISE A LITTLE ABOVE FREEZING ACROSS PARTS OF THE AREA TODAY...
THESE WILL EASILY DROP BACK BELOW FREEZING TONIGHT...AND SHOULD
HELP TO KEEP SNOWMELT AT A MANAGEABLE PACE.

HIGHS ON FRIDAY WILL BE A BIT WARMER...WITH TEMPERATURES LIKELY TO
RISE INTO THE MID 40S TO LOWER 50S ACROSS THE BASINS OF THE BUFFALO
CREEKS...AS WELL AS THOSE OF THE ALLEGHENY AND GENESEE RIVERS.
DESPITE THE WARM TEMPERATURES...THIS STILL IS NOT EXPECTED TO
CAUSE ANY FLOODING. ONE GUIDE USED TO DETERMINE WHEN ICE WILL
BREAK UP IS THAWING DEGREE HOURS (TDH) WHICH IS THE SUM OF THE
ABOVE FREEZING PORTION OF TEMPERATURES BY HOUR. USING THIS
TECHNIQUE...TDH DO NOT REACH 300 THURSDAY AND FRIDAY...EVEN FOR
THE WARMEST BASINS. WHILE IT TYPICALLY TAKES 300 TO 500 TDH FOR
ICE TO BREAK UP...IT MAY TAKE A BIT MORE THAN THAT IN THIS CASE
GIVEN THE THICK ICE THAT IS LIKELY IN PLACE. THIS SAID...THE 
WARM TEMPERATURES WILL HELP TO FURTHER RIPEN THE SNOW PACK AND
INCREASE FLOWS.

AFTER THAT...THE FLOOD RISK SHOULD INCREASE A BIT THIS WEEKEND
WHEN RAINFALL MAY ACCOMPANY THE WARM TEMPERATURES AND ADD TO THE
RUNOFF. HOWEVER...THE FORECAST REMAINS UNCERTAIN WITH RESPECT TO
QPF AND TEMPERATURES. MMEFS ENSEMBLE DATA SUGGESTS THAT IT WOULD
PROBABLY REQUIRE THE WARMEST AND WETTEST OF MODEL SOLUTIONS TO
CAUSE FLOODING...WITH THE GREATEST CHANCE FOR THIS IN THE BUFFALO
CREEKS AND ALLEGHENY BASINS. THERE IS ALSO A SMALL CHANCE FOR ICE
JAMS IN THE BUFFALO CREEKS...BUT IT PROBABLY WILL TAKE TEMPERATURES
ON THE WARM SIDE OF CURRENT GUIDANCE. THE SITUATION WILL CONTINUE
TO BE MONITORED.

&&

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

&&

$$

SYNOPSIS...JJR
NEAR TERM...JJR/THOMAS
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...JJR
MARINE...JJR
HYDROLOGY...APFFEL/JJR







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