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Area Forecast Discussion
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000
FXUS61 KBUF 051128
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
728 AM EDT WED AUG 5 2015

.SYNOPSIS...
A TROUGH OF LOW PRESSURE...AND COOL AIR WILL DROP ACROSS 
THE EASTERN GREAT LAKES REGION TODAY. THIS FEATURE WILL PROVIDE FOR 
CLOUDS ACROSS THE REGION...AND TO THE EAST OF LAKE ONTARIO
SHOWERS AND PERHAPS A THUNDERSTORM. THURSDAY WILL BECOME A FEW
DEGREES WARMER WITH SEASONABLE TEMPERATURES REMAINING FOR THE REST
OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
THIS MORNING'S WATER VAPOR IMAGERY DISPLAYS A BROAD UPPER LEVEL
TROUGH OF LOW PRESSURE OVER EASTERN CANADA. SEVERAL SHORTWAVES
ADVANCING AROUND THIS LOW WILL MAINTAIN THIS UPPER LEVEL LOW'S
INFLUENCE OVER THE EASTERN GREAT LAKES REGION TODAY.

EAST OF LAKE ONTARIO...AS 850 HPA DROP TO NEAR 8C TODAY OVER THE 
LAKE...THE 850 HPA TO LAKE SURFACE TEMPERATURES WILL BE UNSTABLE 
CONTINUING THE THREAT OF LAKE EFFECT RAIN TODAY EAST OF THE LAKE. 
WEAK SURFACE CONVERGENCE WILL FOCUS THESE RAIN BANDS TOWARDS THE TUG 
HILL REGION. 

IN ADDITION THE COOL POOL OF AIR ALOFT WILL CREATE STEEP LAPSE RATES 
SUCH THAT RAIN SHOWERS WILL DEVELOP AS WE WARM TODAY. INSTABILITY 
SHOWERS WILL BE GREATEST IN COVERAGE AREA EAST OF LAKE ONTARIO WHERE 
THE COOLEST AIR ALOFT RESIDES...AND PASSING SHORTWAVE IN THE 
AFTERNOON SHOULD PROVIDE ENOUGH LIFT TO WARRANT LIKELY POPS. IN 
ADDITION THE LOWER FREEZING LEVEL MAY ALLOW FOR SOME RUMBLES OF 
THUNDER ACROSS OSWEGO COUNTY AND THE NORTH COUNTRY THIS AFTERNOON 
AND EARLY EVENING. 

TEMPERATURES AT 850 HPA RANGING FROM NEAR +8C NEAR THE SAINT 
LAWRENCE VALLEY TO +11C NEAR THE NYS/PA STATE LINE WILL BRING COOLER 
THAN NORMAL AFTERNOON HIGHS. TEMPERATURES TODAY WILL AVERAGE ABOUT 5 
DEGREES BELOW NORMAL WITH WIDESPREAD 70S FOUND. WITH THE COOL TROUGH 
OVERHEAD SKIES WILL REMAIN MOSTLY CLOUDY THROUGH THE DAY. GREATEST 
NUMBER OF BREAKS IN THE CLOUDS WILL BE TOWARDS THE NYS/PA LINE. 

TONIGHT LAKE RAIN SHOWERS WILL CONTINUE TO BE POSSIBLE INTO THE 
EVENING HOURS. THIS ACTIVITY STILL REMAINING NEAR THE TUG HILL 
REGION WILL FADE THROUGH THE OVERNIGHT HOURS AS DRIER AIR ASSOCIATED 
WITH AN AREA OF HIGH PRESSURE BUILDING OVER THE GREAT LAKES REGION 
DISRUPTS THE ORGANIZATION OF THE BAND OF RAIN. 

THIS DRIER AIR COMBINED WITH THE INCREASING STABILITY OF THE LOWER 
LEVEL OF THE ATMOSPHERE SHOULD DECREASE THE CLOUD COVER THROUGH THE 
EVENING HOURS. 

TONIGHT LOWS WILL DROP DOWN TO A CHILLY UPPER 40S WELL INLAND TO LOW 
TO MID 50S ACROSS THE LAKE PLAINS. WITH LIGHT WINDS TONIGHT AS HIGH 
PRESSURE NEARS THE REGION SOME RIVER VALLEY FOG IS LIKELY OVER SW 
NYS.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
THE ANOMALOUSLY DEEP CLOSED LOW RESPONSIBLE FOR THE COOL WEATHER 
LEADING INTO THIS PERIOD WILL OPEN UP AND EXIT ACROSS THE LABRADOR 
SEA DURING THIS PERIOD. IN ITS WAKE...A COMPLEX SPLIT FLOW WILL TAKE 
PLACE OVER THE EASTERN HALF OF THE CONTINENT WITH A NEAR ZONAL FLOW 
BEING FOUND OVER THE GREAT LAKES REGION. THIS WILL ENCOURAGE A DAY 
TO DAY MODERATION IN TEMPERATURE...WHILE SFC BASED RIDGING WILL 
VIRTUALLY GUARANTEE RAINFREE CONDITIONS UP TO AT LEAST THE START OF 
THE WEEKEND. 

HIGH PRESSURE CENTERED OVER HUDSON BAY ON THURSDAY WILL NOSE SOUTH 
ACROSS THE LOWER GREAT LAKES TO THE MID ATLANTIC COAST THROUGH 
THURSDAY NIGHT. THIS WILL ENSURE FAIR DRY WEATHER OVER OUR FORECAST 
AREA WITH COMFORTABLE DAYTIME TEMPERATURES TOPPING OUT IN THE MID 
70S WHILE OVERNIGHT LOWS WILL GENERALLY BACK INTO THE 50S. THE  
VALLEYS OF THE SRN TIER AND THE FOOTHILLS TO THE ADIRONDACKS COULD 
REVISIT THE UPPER 40S.

ON FRIDAY...THE AREA OF HIGH PRESSURE WILL PUSH EAST ACROSS NEW 
ENGLAND WHILE WEAK WARM ADVECTION WILL LIFT OUR H85 TEMPS OUT OF THE 
SINGLE DIGITS TO BETWEEN 12 AND 14C. THIS WILL ENCOURAGE OUR MERCURY 
TO CLIMB INTO THE UPPER 70S TO NEAR 80 FRIDAY AFTERNOON...WHICH IS 
RIGHT WHERE THEY SHOULD BE FOR THIS TIME OF YEAR. 

AS THE SFC HIGH MOVES TO EASTERN QUEBEC FRIDAY NIGHT...OUR REGION 
WILL FIND ITSELF SANDWICHED BETWEEN A DEVELOPING STORM SYSTEM OFF 
THE MID ATLANTIC COAST AND A SHORTWAVE OVER THE UPPER GREAT LAKES. 
THIS SHOULD RESULT IN AT LEAST ONE MORE DRY PERIOD FOR OUR FORECAST 
AREA...WITH CONTINUED WARM ADVECTION AND SOMEWHAT MORE CLOUD COVER 
LEADING TO A MILDER NIGHT. OVERNIGHT LOWS SHOULD RANGE FROM THE LOW 
60S ACROSS THE LAKE PLAINS TO THE MID 50S IN THE NORMALLY COOLER 
AREAS SPELLED OUT IN THE DISCUSSION FOR THE PREVIOUS NIGHT.

FOR SATURDAY...THERE WILL BE MORE UNCERTAINTY IN THE FORECAST AS THE 
AFOREMENTIONED SHORTWAVE OVER THE UPPER GREAT LAKES WILL TRACK 
ACROSS LAKE ONTARIO. THE VARIOUS GUIDANCE PACKAGES DIFFER ON THE 
POTENTIAL FOR SHOWERS...WITH THE ECMWF BEING IN THE MORE PESSIMISTIC 
CAMP. WILL DEFER TO CONTINUITY FOR NOW AND HOLD ONTO THE SLGT CHC 
POPS FOR SATURDAY AFTERNOON...BUT THOSE WITH OUTDOOR PLANS SHOULD 
KEEP A CLOSE EYE ON UPDATED FORECASTS AS WE PROGRESS THROUGH THE 
WEEK.

WHILE LOW LEVEL RIDGING MAY STILL EXTEND ACROSS OUR REGION SATURDAY 
NIGHT...THE SHORTWAVE CROSSING TO OUR NORTH COULD GENERATE A FEW 
SHOWERS ACROSS THE EASTERN LAKE ONTARIO REGION. HAVE INTRODUCED LOW 
CHC POPS FOR THAT AREA WHILE KEEPING SLGT CHC POPS IN PLACE 
ELSEWHERE.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
THE SPLIT UPPER LEVEL FLOW FOUND OVER NORTH AMERICA WILL EVOLVE INTO 
A PHASED LONGWAVE PATTERN DURING THIS PERIOD...AS A BURGEONING RIDGE 
WILL TAKE SHAPE OVER THE CANADIAN AND U.S. PLAINS. WHILE THIS 
PROCESS WILL KEEP A FAIR AMOUNT OF UNCERTAINTY AS TO THE TIMING AND 
EXTENT OF RAINFALL FOR THIS PERIOD...THERE IS FAIRLY HIGH CONFIDENCE 
THAT OUR TEMPERATURES WILL AVERAGE WITHIN A COUPLE DEGREES OF 
NORMAL. 

AN EXITING SHORTWAVE OVER THE ST LAWRENCE VALLEY WILL GIVE WAY TO A 
WEDGE OF HIGH PRESSURE SUNDAY AND SUNDAY NIGHT. THIS SHOULD FAVOR 
MAINLY DRY WEATHER OVER OUR FORECAST AREA...BUT AGAIN...GUIDANCE HAS 
NOT BEEN CONSISTENT WITH THE NUANCES OF THIS SCENARIO SO WILL HOLD 
ONTO SLGT CHC POPS.

AS WE PUSH INTO THE NEW WORK WEEK...CONFIDENCE IN THE OVERALL 
PATTERN ACTUALLY INCREASES AS AN AMPLIFYING RIDGE OVER THE PLAINS 
WILL SET THE STAGE FOR A DEEPENING DOWNSTREAM TROUGH OVER THE LOWER 
GREAT LAKES. MEANWHILE...A BROAD INVERTED TROUGH STRETCHING FROM THE 
GREAT LAKES SOUTH TO THE LOWER MISSISSIPPI VALLEY ON MONDAY WILL 
PUSH EAST MONDAY NIGHT AND TUESDAY. SOME OF THE ECMWF AND GEFS 
ENSEMBLE MEMBERS ARE SUGGESTING THAT AN ORGANIZED SFC LOW WILL 
DEVELOP WITHIN THIS TROUGH AND LIFT OUT OF THE OHIO VALLEY ON 
TUESDAY. EVEN IF THIS SCENARIO DOES NOT TAKE PLACE...THERE WILL BE 
AN INCREASING CHC FOR UNSETTLED WEATHER ACROSS OUR REGION AS WE 
PROGRESS THROUGH THE FIRST COUPLE DAYS OF THE NEW WORK WEEK.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
VFR FLIGHT CONDITIONS ARE FOUND ACROSS THE REGION AT 12Z. 

A COOL POOL OF AIR ALOFT WILL DROP ACROSS THE REGION MAINTAINING 
CIGS...THOUGH CLOUDS WILL GENERALLY HAVE BASES BETWEEN 5 AND 10K 
FEET. THE GREATEST CHANCES FOR SHOWERS WILL BE EAST OF LAKE ONTARIO 
TODAY WHERE SHOWERS WILL BECOME LIKELY AND WILL CARRY 
-SHRA IN THE KART TAF. SOME THUNDER IS ALSO POSSIBLE EAST OF LAKE 
ONTARIO TODAY. ELSEWHERE THE REMAINING TAF SITES SOUTH OF LAKE 
ONTARIO SHOULD REMAIN DRY.  

AS WE HEAD TOWARDS TONIGHT SCATTERED SHOWERS/LAKE ENHANCED SHOWERS 
WILL LINGER SOUTHEAST OF LAKE ONTARIO. THIS ACTIVITY WILL WANE SUCH 
THAT BY DAWN THURSDAY MORNING MUCH OF THE REGION SHOULD BE 
PRECIPITATION FREE WITH JUST A FEW PATCHES OF CLOUDS...MAINLY EAST 
AND SOUTHEAST OF LAKE ONTARIO. 

WINDS TODAY WILL GENERALLY BE WESTERLY...WITH OCCASIONAL GUSTS THIS 
AFTERNOON OF 20 KNOTS. TONIGHT WINDS WILL GO LIGHT AND VARIABLE AS 
HIGH PRESSURE MEANDERS ACROSS THE GREAT LAKES REGION. 

OUTLOOK... 
THURSDAY THROUGH SUNDAY...VFR.

&&

.MARINE...
SMALL CRAFT ADVISORIES WILL REMAIN IN EFFECT FOR LAKE 
ONTARIO TODAY AS A POOL OF COLD AIR ALOFT DROPS OVER THE LAKE. 
WESTERLY WINDS WILL KICK UP 4 TO 6 FOOT WAVES OVER CENTRAL AND 
EASTERN PORTIONS OF THE LAKE TODAY AND THIS EVENING. 

SOUTHWEST TO WESTERLY WINDS WILL ALSO NEAR SMALL CRAFT CONDITIONS ON 
LAKE ERIE THIS AFTERNOON. THOUGH LAPSE RATES FROM THE WATER SURFACE 
WILL NOT BE AS GREAT AS LAKE ONTARIO...STILL BELIEVE THAT SCA 
CONDITIONS WILL BE MEET AND WILL ISSUE A SCA FOR THIS LAKE TO 
ACCOUNT FOR WINDS NEARING 20 KNOTS AND WAVES INCREASING TOWARDS 4 
FEET. 
 
IN ADDITION TO THE WINDS AND WAVES...THERE WILL CONTINUE TO REMAIN A 
POSSIBILITY OF WATERSPOUTS TODAY...ESPECIALLY ON LAKE ONTARIO. LARGE 
WATER SURFACE TO 850 HPA TEMPERATURE DIFFERENCE AND EQUILIBRIUM 
LEVELS RISING TO 25 TO 30K FEET SHOULD CONTINUE THE POSSIBILITY OF 
WATERSPOUT FORMATION UNDER THIS UPPER LEVEL LOW ALOFT. 

HIGH PRESSURE WILL BUILD TOWARDS THE EASTERN GREAT LAKES REGION 
TONIGHT ENDING THE THREAT OF WATERSPOUTS...WHILE ALSO ALLOWING FOR 
WINDS AND WAVES TO DIMINISH ON THE LAKES.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 8 PM EDT THIS 
         EVENING FOR LEZ040-041.
         SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR 
         LOZ043>045.
         SMALL CRAFT ADVISORY FROM NOON TODAY TO 6 PM EDT THIS 
         EVENING FOR LOZ042.

&&

$$

SYNOPSIS...THOMAS
NEAR TERM...THOMAS
SHORT TERM...RSH
LONG TERM...RSH
AVIATION...THOMAS
MARINE...THOMAS



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