Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 020300
AFDBUF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
1100 PM EDT SAT AUG 1 2015

.SYNOPSIS...
HIGH PRESSURE WILL BRING DRY AND WARM CONDITIONS ON SUNDAY TO WRAP
UP THE WEEKEND. A COLD FRONT WILL CROSS THE AREA SUNDAY NIGHT AND
MONDAY WITH A BETTER CHANCE OF MORE WIDESPREAD SHOWERS AND
THUNDERSTORMS. THIS COLD FRONT WILL USHER IN MUCH COOLER AIR THAT
WILL LAST FOR ALL OF NEXT WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
RADAR IS CLEAR LATE THIS EVENING WITH THE MID-LEVEL TROUGH EAST OF
THE FORECAST AREA AND HIGH PRESSURE EDGING IN FROM THE OHIO VALLEY.
BOTH WILL WORK TO KEEP A DRY OVERNIGHT. EXPECT MAINLY CLEAR TO
PARTLY CLOUDY SKIES WITH JUST A FEW PATCHES OF STRATUS DRIFTING
ACROSS THE AREA. THERE WILL BE A WIDE RANGE IN LOWS TONIGHT WITH MID
60S ON THE LAKE PLAINS WHERE A BREEZE WILL STAY UP THROUGH THE
NIGHT. THE SOUTHERN TIER VALLEYS AND TUG HILL REGION WILL DECOUPLE
MORE...WITH LOWS IN THE LOWER TO MID 50S IN THE COOLEST LOCATIONS.

ON SUNDAY HIGH PRESSURE WILL REMAIN IN PLACE FROM THE OHIO VALLEY TO
THE MID ATLANTIC. THIS HIGH WILL BE CLOSE ENOUGH TO PROVIDE
SUBSIDENCE AND DRYING...WHICH WILL LIKELY PREVENT ANY DIURNAL
CONVECTION DESPITE THE WARM TEMPERATURES. EXPECT NOTHING MORE THAN
SCT DIURNAL CUMULUS TO DEVELOP ALONG AND INLAND FROM THE LAKE BREEZE
BOUNDARIES AND ALSO SOME MODEST INCREASE IN CIRRUS LEVEL CLOUDINESS
DURING THE AFTERNOON. WARM ADVECTION AHEAD OF THE NEXT SYSTEM WILL
BOOST 850MB TEMPS TO AROUND +16...WHICH WILL SUPPORT HIGHS IN THE
MID 80S ACROSS LOWER ELEVATIONS AND AROUND 80 ON THE HILLS.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
SUNDAY NIGHT A SHORTWAVE TROUGH OF LOW PRESSURE WILL DIG TOWARDS
THE BASE OF AN UPPER LEVEL LOW THAT IS SPINNING OVER ONTARIO
PROVINCE CANADA. AT THE SURFACE AN AREA OF LOW PRESSURE NEAR THE
SOUTHERN TIP OF JAMES BAY WILL BE DRAGGING A COLD FRONT ACROSS THE
CENTRAL GREAT LAKES.

FOR OUR REGION A WARM AND SOMEWHAT HUMID NIGHT IS ON TAP AS A STRONG
LOW LEVEL JET OF 45 TO 60 KNOTS WITHIN THE 850 - 700 HPA LAYER
STRENGTHENS THE WARM AIR ADVECTION. THIS JET WILL ALSO BE DRAWING
MOISTURE NORTHWARD AS PWATS CLIMB TO NEAR 1.5 INCHES ACROSS
WESTERN AND CENTRAL NEW YORK THROUGH THE NIGHT.

THE COLD FRONT WILL BE SLICING ACROSS THE CENTRAL GREAT LAKES REGION
SUNDAY NIGHT...TO BE KNOCKING ON OUR WESTERN DOORSTEPS MONDAY
MORNING. THROUGH THE OVERNIGHT A FEW SHOWERS ARE POSSIBLE AS
CONVERGENCE AHEAD OF THE LOW LEVEL JET PRODUCES ENOUGH LIFT TO FORM
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS. GREATEST COVERAGE
AREA WILL BE NEAR THE LAKES...WHICH WILL BE HOLDING ONTO INSTABILITY
THROUGH THE OVERNIGHT. LATER IN THE NIGHT SHOWERS WILL BEGIN TO
INCREASE IN NUMBER ACROSS FAR WESTERN NEW YORK AND THE SAINT
LAWRENCE VALLEY AS THE COLD FRONT DRAWS NEAR.

ON MONDAY THE UPPER LEVEL SHORTWAVE WILL BE PUSHING A FAIRLY STRONG
COLD FRONT ACROSS THE REGION. AHEAD OF THE COLD FRONT A PREFRONTAL
TROUGH IS EXPECTED TO FORM WITH A LINE OF SHOWERS AND THUNDERSTORMS
ADVANCING EASTWARD ACROSS THE BUFFALO CWA. CURRENT MODEL/THINKING
FOR THE TIMING OF THIS INITIAL LINE OF STORMS IS TO BE ACROSS WNY
MONDAY MORNING...REACHING CENTRAL NEW YORK MIDDAY. THOUGH THIS IS AN
EARLY IN THE DAY TIMING TO THE BAND OF THUNDERSTORMS (AND NOT DURING
THE TIME OF PEAK HEATING AND INSTABILITY)...THERE WILL STILL BE A
DECENT AMOUNT OF INSTABILITY AROUND COUPLED WITH STEEPING LAPSE
RATES TO NEAR 7 TO 8 C/KM AND 0-6KM BULK SHEAR VALUES UP TO 40 KNOTS
TO ALLOW A FEW OF THESE THUNDERSTORMS TO BECOME STRONG TO POSSIBLY
SEVERE. WILL MENTION THIS PROSPECT IN THE HWO.

FOLLOWING THE INITIAL LINE OF SHOWERS AND THUNDERSTORMS THERE WILL
BE A BRIEF BREAK IN PRECIPITATION. IN FACT THE SUN MIGHT EVEN APPEAR
BRIEFLY DURING THE MIDDAY AND EARLY AFTERNOON HOURS. WITHIN THIS
SUNSHINE SOUTHWEST WINDS COULD BECOME GUSTY AS MIXING HEIGHTS RISE.
GUSTS UP TO 20 TO 25 MPH...AND NEAR 30 MPH DOWNWIND OF THE EASTERN
GREAT LAKES WILL BE POSSIBLE AHEAD OF THE COLD FRONT. CLOUDS WILL
THICKEN AGAIN IN THE AFTERNOON AND SHOWER CHANCES SHALL INCREASE
WITH THE LATE DAY PASSAGE OF THE SURFACE COLD FRONT. MUCH OF THE
INSTABILITY WILL LIKELY BE USED TO FUEL THE INITIAL LINE OF
STORMS...SUCH THAT THE SECOND LINE WILL TEND TO BE MORE OF A BROKEN
LINE OF SHOWERS WITH ISOLATED THUNDER CHANCES.

FOLLOWING THE PASSAGE OF THIS COLD FRONT OUR 850 HPA TEMPERATURES
WILL DROP FROM THE HIGH TEENS DOWN TO NEAR 10C BY TUESDAY MORNING.
SHOWER CHANCES WILL DIMINISH THROUGH THE NIGHT MONDAY NIGHT WITH
SOME PATCHY AREAS OF FOG FORMING OVER A WET GROUND.

TUESDAY WILL HAVE MORE OF A FALLISH FEEL TO THE DAY AS A POOL OF
COLD AIR ALOFT PASSES OVER THE EASTERN GREAT LAKES. TEMPERATURES AT
850 HPA IN THE HIGH SINGLE DIGITS WILL GENERATE STEEP LAPSE RATES
THAT COULD GENERATE A FEW SHOWERS. IN ADDITION TO THE INSTABILITY
SHOWERS A WESTERLY FLOW OVER THE WARM GREAT LAKES COULD BRING SOME
LAKE ENHANCED SHOWERS ACROSS SW NYS AS WELL AS SE AND EAST OF
LAKE ONTARIO. EXPECT SHOWER COVERAGE TO DIMINISH THROUGH THE NIGHT
TUESDAY NIGHT AS LAPSE RATES WEAKEN WITH THE SETTING SUN.

TEMPERATURES SUNDAY NIGHT WILL REMAIN MILD OVERNIGHT WITH LOWS
REMAINING IN THE LOWER 70S FOR MOST LOCATIONS NEAR THE GREAT
LAKES...WHILE INLAND AREAS AND THE NORTH COUNTRY DROP BACK INTO
THE MID TO UPPER 60S. ON MONDAY THESE SEASONABLY WARM TEMPERATURES
WILL FALL BACK INTO THE UPPER 50S AND LOWER 60S MONDAY NIGHT. WITH
THE COOL POOL OVER THE REGION TUESDAY EXPECT HIGHS TO BE WELL
BELOW EARLY AUGUST NORMALS...WITH HIGHS ONLY IN THE LOWER 70S.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AN UPPER LEVEL TROUGH WILL START THIS TIME PERIOD OVER EASTERN
CANADA...WITH BELOW NORMAL TEMPERATURES FOUND UNDER THIS FEATURE.
THIS TROUGH WILL WEAKEN SOME THROUGH THE TIME PERIOD BUT WILL
REMAIN GENERALLY IN PLACE AND NOT ALLOW FOR AN UPPER LEVEL RIDGE
FOUND OVER THE DESERT SOUTHWEST...AND PLAIN STATES TO PUSH
EASTWARD TO THE ATLANTIC COASTLINE.

MOISTURE WILL BE LIMITED THE FIRST PART OF THE EXTENDED TIME FRAME
WITH PARTLY SUNNY SKIES PREDOMINATE. THERE WILL BE SMALL CHANCES FOR
SHOWERS...WITH CONFIDENCE FOR CHANCE POPS ONLY EAST OF LAKE ONTARIO
WHICH WILL BE CLOSER TO BOTH THE UPPER LEVEL TROUGH AND DEEPER
MOISTURE. IN ADDITION ON WEDNESDAY A COOL POOL ALOFT MAY BRING
ENOUGH INSTABILITY OVER LAKE ONTARIO TO BRING SOME LAKE ENHANCED
RAIN SHOWERS SE AND E OF THE LAKE.

TOWARDS THE END OF THE EXTENDED PERIOD DEEPER MOISTURE WILL ADVECT
NORTHWARD AND ADDITIONAL SHORTWAVES ROUNDING THE UPPER LEVEL TROUGH
WILL BRING INCREASED CHANCES FOR SHOWERS AND THUNDERSTORMS TO CLOSE
OUT THE EXTENDED. TEMPERATURES WILL REMAIN SLIGHTLY COOLER THAN
NORMAL THIS PERIOD.

&&

.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
RADAR IS CLEAR ACROSS THE FORECAST AREA LATE THIS EVENING WITH VFR
EXPECTED OVERNIGHT. MAINLY CLEAR TO PARTLY CLOUDY SKIES EXPECTED
WITH JUST A FEW PATCHES OF VFR LEVEL STRATUS. THERE SHOULD BE
JUST ENOUGH WIND TO PREVENT ANY RIVER VALLEY FOG LATE TONIGHT.

ON SUNDAY HIGH PRESSURE WILL REMAIN IN CONTROL FROM THE OHIO VALLEY
TO THE MID ATLANTIC. THIS SHOULD PROVIDE ENOUGH SUBSIDENCE TO
PREVENT ANY CONVECTION UNTIL A SYSTEM BEGINS TO APPROACH FROM THE
WEST SUNDAY EVENING. VFR WILL PREVAIL THROUGH THE DAY WITH JUST SCT
DIURNAL CUMULUS AND SOME MODEST INCREASE IN CIRRUS LEVEL CLOUDINESS.
LOW CHANCES OF -SHRA/TSRA ARRIVE TOWARD 00Z MONDAY WITH AN
APPROACHING COLD FRONT. GUIDANCE INDICATES A 40+ KT LOW LEVEL JET
WILL SHIFT IN AHEAD OF THE COLD FRONT WHICH COULD BRING SOME WIND
SHEAR.

OUTLOOK...
SUNDAY NIGHT...MAINLY VFR WITH SCATTERED SHOWERS AND
THUNDERSTORMS AND ASSOCIATED BRIEF/LOCAL MVFR/IFR CONDITIONS. LLWS
POSSIBLE IN THE EVENING.
MONDAY...VFR TO OCCASIONALLY MVFR WITH SHOWERS AND STORMS LIKELY.
TUESDAY...MAINLY VFR WITH A CHANCE OF A FEW LIGHT SHOWERS.
WEDNESDAY AND THURSDAY...MAINLY VFR.

&&

.MARINE...
WINDS HAVE DIMINISHED LATE THIS EVENING AS THE PRESSURE GRADIENT
RELAXES WITH HIGH PRESSURE BUILDING IN FROM THE OHIO VALLEY. WINDS
WILL INCREASE TO AROUND 15 KNOTS AGAIN ON SUNDAY... BUT CONDITIONS
ARE EXPECTED TO REMAIN JUST BELOW SMALL CRAFT ADVISORY CRITERIA.

A STRONGER COLD FRONT WILL CROSS THE AREA SUNDAY NIGHT AND MONDAY
AND LIKELY BRING ANOTHER ROUND OF SMALL CRAFT ADVISORY CONDITIONS TO
LAKES ERIE AND ONTARIO.

&&

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

&&

$$

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



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