978
FXUS61 KBUF 201759
AFDBUF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BUFFALO NY
159 PM EDT MON JUL 20 2026
WHAT HAS CHANGED
MINOR CHANGES TO THE FORECAST WITH THIS UPDATE.
KEY MESSAGES
1) A STRONG COLD FRONT WILL BRING THE NEXT ROUND OF SHOWERS AND
THUNDERSTORMS TUESDAY THROUGH TUESDAY NIGHT. SOME STORMS MAY BE
SEVERE.
2) COOL WEDNESDAY, WITH A CHANCE OF A FEW LINGERING SHOWERS AND
ISOLATED THUNDERSTORMS.
DISCUSSION
KEY MESSAGE 1...A STRONG COLD FRONT WILL BRING THE NEXT ROUND
OF SHOWERS AND THUNDERSTORMS TUESDAY THROUGH TUESDAY NIGHT. SOME
STORMS MAY BE SEVERE.
AN ACTIVE TUESDAY IS EXPECTED AS AN UNSEASONABLY STRONG MID LEVEL
TROUGH DIGS INTO THE GREAT LAKES, WITH MID LEVEL HEIGHT FALLS, DPVA,
AND UPPER LEVEL DIVERGENCE AHEAD OF THE TROUGH ALL CONTRIBUTING TO A
BACKGROUND OF LARGE SCALE ASCENT. THE AIRMASS TODAY IS QUITE DRY,
BUT INCREASING SOUTHWESTERLY FLOW AHEAD OF THE TROUGH WILL TRANSPORT
IMPROVED MOISTURE INTO THE REGION BY MIDDAY TUESDAY, WITH SURFACE
DEWPOINTS RISING TO THE MID TO UPPER 60S. STRONG LOW/MID LEVEL FLOW
BY MID SUMMER STANDARDS WILL CROSS THE EASTERN GREAT LAKES,
SUPPORTING MODERATE TO STRONG SHEAR PROFILES.
WHILE THE LARGE SCALE SETUP IS CERTAINLY FAVORABLE FOR SEVERE
THUNDERSTORMS, HIGH-RES CAMS GUIDANCE CONTINUES TO SUGGEST A MESSY
STORM EVOLUTION. DEBRIS CLOUDS AND SCATTERED SHOWERS WILL LIKELY
CROSS THE REGION IN THE MORNING FROM DECAYING UPSTREAM CONVECTION.
IF THIS PERSISTS LONG ENOUGH, IT MAY RESTRICT DESTABILIZATION TO
SOME EXTENT. INITIAL SSW FLOW WILL GRADUALLY VEER TO THE SW THROUGH
THE DAY, WITH STABLE LAKE SHADOWS EXPANDING NORTHEAST OF THE LAKES
AND DIMINISHING INSTABILITY ACROSS THE NIAGARA FRONTIER AND
JEFFERSON COUNTY.
CONVECTIVE INITIATION WILL LIKELY OCCUR BY MIDDAY TO EARLY AFTERNOON
ALONG 1) A STRENGTHENING LAKE BREEZE BOUNDARY FROM THE SOUTHERN TIER
INTO THE FINGER LAKES AND 2) POSSIBLY AN OUTFLOW BOUNDARY AND/OR
MCV FROM LEFTOVER UPSTREAM CONVECTION MOVING INTO THE AREA FROM THE
WEST. IF THE OUTFLOW BOUNDARY OR MCV ENDS UP BEING THE MAIN FOCUS
FOR CONVECTION, THAT COULD POTENTIALLY OVERCOME THE NEGATIVE IMPACTS
OF STABLE LAKE SHADOWS. STILL, THE MOST LIKELY LOCATION OF SEVERE
WEATHER AND BEST COVERAGE OF SHOWERS AND THUNDERSTORMS IN GENERAL
WILL BE TUESDAY AFTERNOON AND EARLY EVENING FROM THE SOUTHERN TIER
INTO THE FINGER LAKES AND CENTRAL NY, AWAY FROM THE STABILIZING
INFLUENCE OF THE LAKES.
THE SHEAR/INSTABILITY PROFILES WILL SUPPORT MULTIPLE MODES OF
CONVECTION INCLUDING MULTICELL CLUSTERS, BOWING SEGMENTS, AND
SUPERCELLS. THE PRIMARY RISK WILL BE ISOLATED DAMAGING WIND GUSTS IN
THE STRONGER, MORE SUSTAINED STORMS. IF BOWING SEGMENTS DEVELOP,
CORRIDORS OF WIND DAMAGE ARE POSSIBLE. FORECAST SOUNDINGS SHOW MORE
FAVORABLY CURVED HODOGRAPHS AND HIGH EFFECTIVE SRH VALUES ACROSS THE
SOUTHERN TIER AND FINGER LAKES, WHERE AN ISOLATED TORNADO IS
POSSIBLE. STORM MOTION WILL BE QUITE FAST GIVEN THE STRONG WIND
FIELDS, BUT STORMS WILL PRODUCE BRIEF, TORRENTIAL DOWNPOURS WITH A
LOW RISK OF ISOLATED FLASH FLOODING IF TRAINING OCCURS ALONG LAKE
BREEZE BOUNDARIES.
THE ACTUAL COLD FRONT WILL NOT CROSS THE AREA UNTIL TUESDAY EVENING,
AND MAY PRODUCE ANOTHER LINE OF SHOWERS AND SCATTERED THUNDERSTORMS.
COVERAGE OF SHOWERS AND ESPECIALLY THUNDER WILL DIMINISH BY MID TO
LATE EVENING WITH THE LOSS OF DIURNAL INSTABILITY.
KEY MESSAGE 2...COOL WEDNESDAY, WITH A CHANCE OF A FEW LINGERING
SHOWERS AND ISOLATED THUNDERSTORMS.
THE DIGGING TROUGH WILL BRIEFLY DEVELOP INTO A MID LEVEL CLOSED LOW
OVER WESTERN QUEBEC WEDNESDAY. DEEP MOISTURE WILL BE EAST OF THE
AREA BY WEDNESDAY MORNING, BUT FORCING FOR ASCENT FROM SEVERAL
SHORTWAVES ROUNDING THE BASE OF THE TROUGH COUPLED WITH COOL AIR
ALOFT WILL STILL SUPPORT A FEW SCATTERED SHOWERS THROUGH THE DAY,
AND POSSIBLY AN ISOLATED THUNDERSTORM OR TWO. BOTH INTENSITY AND
COVERAGE WILL BE FAR LESS THAN TUESDAY.
TEMPERATURES WILL BE QUITE COOL WEDNESDAY, CLOSE TO 10F BELOW
AVERAGE FOR MID SUMMER. HIGHS WILL STRUGGLE TO REACH THE LOWER 70S
FOR LOWER ELEVATIONS, WITH MID 60S ACROSS HIGHER TERRAIN. LOWS
WEDNESDAY NIGHT WILL DROP BACK INTO THE 50S IN MOST AREAS, WITH MID
40S FOR THE SOUTHERN TIER VALLEYS AND LEWIS COUNTY.
AVIATION /18Z MONDAY THROUGH SATURDAY/
OTHER THAN SOME DIURNAL CU (FEW-SCT COVERAGE) INLAND FROM THE LAKES
THIS AFTERNOON, WIDESPREAD VFR CONDITIONS WILL PERSIST THROUGH
TONIGHT AS HIGH PRESSURE SLIDING OFF THE SOUTHERN NEW ENGLAND COAST
REMAINS IN CONTROL. WINDS WILL BE SW'ERLY TO W'ERLY THROUGH EARLY
EVENING, WITH GUSTS UP TO 20 KNOTS POSSIBLE DOWNWIND OF THE LAKES
(KBUF/KIAG/KART) THROUGH THE AFTERNOON. WINDS BECOME LIGHT WHILE
BACKING TO THE SOUTH LATER THIS EVENING, BEFORE SOUTHERLY FLOW
BEGINS TO RAMP UP LATER TONIGHT AS THE PRESSURE GRADIENT STARTS TO
TIGHTEN WELL AHEAD OF AN APPROACHING COLD FRONT. MID LEVEL DECKS
WILL START TO INCREASE FROM THE WEST LATER TONIGHT AS WELL.
VFR FLIGHT CONDITIONS ARE EXPECTED TUESDAY MORNING WITH JUST MAINLY
THICKENING AND LOWERING MID LEVEL DECKS. S'ERLY TO SW'ERLY FLOW WILL
CONTINUE TO RAMP UP THROUGH THE FIRST HALF OF THE DAY, WITH
WIDESPREAD GUSTS OF 20-25 KNOTS AREAWIDE FROM MID MORNING ON, AND
GUSTS UP TO 30 KNOTS POSSIBLE NORTHEAST OF LAKE ERIE. A PERIOD OF
MARGINAL LLWS STILL LOOKS POSSIBLE NEAR THE START OF TUESDAY
MORNING, HOWEVER IT APPEARS THAT JUST AS THE STRONGER WINDS ALOFT
COME OVERHEAD, AT LEAST PARTIAL MIXING OF THOSE WINDS TO THE SURFACE
WILL ALREADY BE UNDERWAY WHICH MAY MITIGATE MOST OF THE LLWS
CONCERNS. OTHERWISE, A FEW SHOWERS AND STORMS WILL BE POSSIBLE
TOWARD THE TAIL END (18Z) OF THE TAF PERIOD, BECOMING MORE
WIDESPREAD DURING THE AFTERNOON HOURS WITH DETERIORATING FLIGHT
CONDITIONS. A FEW STORMS MAY BE SEVERE TUESDAY AFTERNOON/EVENING
WITH STRONG WINDS BEING THE PRIMARY RISK.
OUTLOOK...
TUESDAY NIGHT...RESTRICTIONS LIKELY IN PERIODIC SHOWERS AND
THUNDERSTORMS.
WEDNESDAY...RESTRICTIONS LIKELY WITH LINGERING SHOWERS/ISOLATED
THUNDERSTORM.
THURSDAY AND SATURDAY...MAINLY VFR.
MARINE
SOUTH-SOUTHWEST WINDS WILL BEGIN TO INCREASE ON THE LAKES OVERNIGHT,
AND INCREASE FURTHER ON TUESDAY WHILE GRADUALLY VEERING MORE TO THE
SOUTHWEST. SMALL CRAFT ADVISORY CONDITIONS ARE LIKELY ON LAKE ERIE,
THE WEST END OF LAKE ONTARIO, AND NORTHEAST END OF LAKE ONTARIO
WHERE WINDS ARE THE STRONGEST TUESDAY. A COLD FRONT WILL MOVE ACROSS
THE LOWER GREAT LAKES TUESDAY NIGHT. WEST TO WEST-NORTHWEST WINDS
WILL INCREASE LATE TUESDAY NIGHT AND WEDNESDAY, ESPECIALLY ON LAKE
ONTARIO WITH SOLID SMALL CRAFT ADVISORY CONDITIONS.
SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED FROM LATE
MORNING THROUGH EVENING TUESDAY. A FEW STORMS MAY CONTAIN GUSTY
WINDS AND LOCALLY HIGHER WAVES.
BUF WATCHES/WARNINGS/ADVISORIES
NY...NONE.
MARINE...NONE.
DISCUSSION...HITCHCOCK
AVIATION...JM
MARINE...HITCHCOCK
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