658
FXUS61 KBTV 020058
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
858 PM EDT SAT AUG 1 2026
WHAT HAS CHANGED
AS OF 241 PM EDT SATURDAY...
HAVE INCREASED THE RAINFALL TOTALS ACROSS THE ST. LAWRENCE VALLEY
AND PORTIONS OF THE ADIRONDACKS TO RANGE BETWEEN 1 TO 1.5
INCHES, WITH LOCALLY HIGHER AMOUNTS POSSIBLE WITHIN ANY
CONVECTIVE ACTIVITY. AN ISOLATED FLASH FLOOD THREAT ACROSS
NORTHERN NEW YORK REMAINS FOR LATE SUNDAY INTO EARLY MONDAY WITH
SLOW-MOVING SHOWERS AND THUNDERSTORMS POSSIBLE.
KEY MESSAGES
AS OF 241 PM EDT SATURDAY...
1. SHOWERS AND EMBEDDED THUNDERSTORMS WILL INCREASE ACROSS THE
REGION SUNDAY INTO MONDAY. LOCALLY HEAVY RAINFALL POSSIBLE,
ESPECIALLY IN THE ST. LAWRENCE VALLEY.
2. A CHANCE OF SHOWERS AND THUNDERSTORMS PERSISTS OVER THE SECOND
HALF OF NEXT WEEK.
DISCUSSION
AS OF 241 PM EDT SATURDAY...
KEY MESSAGE 1: A SLOW MOVING UPPER LEVEL TROUGH WITH ASSOCIATED CLOSED
SURFACE LOW IS CURRENTLY CENTERED ACROSS THE OHIO VALLEY AND WILL
TRACK TO THE EAST NORTHEAST TODAY INTO TOMORROW. A BAROCLINIC ZONE
IS ALSO SET UP ACROSS THE GREAT LAKES AND EASTERN ONTARIO BRINGING
SOME ISOLATED SHOWER CHANCES TODAY ACROSS THE ST. LAWRENCE VALLEY.
AS THIS SYSTEM TRACKS EAST, CLOUD COVER WILL INCREASE AREAWIDE INTO
TONIGHT WITH SOUTH TO SOUTHWEST CHANNELED FLOW JUST ABOVE THE
SURFACE, WHICH SHOULD HELP LIMIT, OR PREVENT ALTOGETHER, THE
COVERAGE OF ANY POTENTIAL FOG TONIGHT.
INTO TOMORROW, THE SYSTEM WILL APPROACH THE ST. LAWRENCE VALLEY AND
THE NORTH COUNTRY WITH SHOWER CHANCES INCREASING BY MIDDAY SUNDAY.
THERMODYNAMIC PROFILES DENOTE SOME SKINNY SBCAPE BETWEEN 500-
1000J/KG WHICH WILL ALLOW FOR AT LEAST SOME ISOLATED CONVECTION AND
THUNDERSTORM ACTIVITY. THIS ACTIVITY WILL LIKELY BE CONFINED TO NEAR
THE ST. LAWRENCE RIVER AND ALONG US-11 IN ST. LAWRENCE COUNTY.
MODEST TO WEAK MID LEVEL FLOW BETWEEN 20-30 KNOTS WITH PWATS
APPROACHING 1.8-2", AND DEEP WARM LAYER CLOUD DEPTHS, LOCALLY HEAVY
RAIN WITHIN ANY CONVECTION WILL BE POSSIBLE. WPC HAS KEPT THE ST.
LAWRENCE VALLEY IN A SLIGHT (RISK LEVEL 2 OUT OF 4) FOR A AT LEAST A
15% CHANCE OF EXCEEDING FLASH FLOOD GUIDANCE. THE AXIS OF THESE
SHOWERS REMAINS SOMEWHAT VARIABLE FROM RUN TO RUN ACROSS THE HI RES
CAMS. THE NAM3 KEEPS MUCH OF THE CONVECTIVE ACTIVITY DURING THE DAY
TOMORROW OVER THE BORDER IN ONTARIO, WHEREAS THE HRRR RIDES THE AXIS
OF INSTABILITY OVER WESTERN ST. LAWRENCE COUNTY. WHERE THIS
DEFORMATION BOUNDARY SETS UP WILL HAVE A LARGE IMPACT ON THE TOTAL
RAINFALL FROM THIS SYSTEM. RIGHT NOW HAVE KEPT THE CONVECTIVE
ACTIVITY ON THE US SIDE OF THE BORDER WITH A MORE STABLE RUN TO RUN
CONSISTENT HRRR SOLUTION. SHOULD AN AREA SEE REPEATED ROUNDS OF
SHOWERS, ESPECIALLY WITH ANTECEDENT RAINFALL, FLASH FLOODING CANNOT
BE RULED OUT. HOWEVER, THE ST. LAWRENCE VALLEY AT THE PRESENT TIME
IS NOT EXPECTED TO SEE SIGNIFICANT ENOUGH RAINFALL TO PRODUCE
FLOODING OVER THE PREVAILING FLATTER TERRAIN.
TOWARDS SUNDAY EVENING AND SUNDAY NIGHT, THE DEFORMATION BOUNDARY
WILL SHIFT EAST INTO THE CHAMPLAIN VALLEY AND VERMONT BY MONDAY
MORNING. THERE IS GOOD AGREEMENT THAT OVERNIGHT SUNDAY SHOULD HAVE
THE BETTER RAINFALL COVERAGE AND CONTAIN THE BULK OF THE RAINFALL. A
FEW AREAS OF BRIEF 0.25-0.5 INCH/HOUR RATES WILL BE POSSIBLE ACROSS
NORTHERN NEW YORK WITHIN THE BOUNDARY AS IT SHIFTS EAST TOWARDS
VERMONT. SHOWERS WILL SLOWLY TAPER OFF BY MONDAY AFTERNOON ACROSS
EASTERN VERMONT WITH FOG DEVELOPMENT LIKELY IN THE VALLEYS OF THE
REGION WITH BRIEF HIGH PRESSURE NUDGING IN. CURRENTLY HAVE INCREASED
RAINFALL TOTALS ACROSS THE ST. LAWRENCE VALLEY, WITH NEW GUIDANCE.
TOTAL RAINFALL FOR MOST OF THE REGION WILL BE AROUND 0.5 INCHES.
LOCALLY HIGHER AMOUNTS BETWEEN AN INCH TO AN INCH AN A HALF WILL BE
POSSIBLE FROM THE FOOTHILLS OF THE ADIRONDACKS INTO THE ST. LAWRENCE
VALLEY, ESPECIALLY UNDER ANY CONVECTIVE ACTIVITY. TUESDAY WILL BE
DRIER AND CALMER WITH TEMPERATURES IN THE UPPER 70S TO LOW 80S AND
CLEARING SKIES.
KEY MESSAGE 2: A SLOW MOVING TO STATIONARY FRONT WILL BE DRAPED ACROSS OUR
REGION FOR THE SECOND HALF OF NEXT WEEK BRINGING REPEATED ROUNDS OF
SHOWERS AND THUNDERSTORMS. WHILE THE SHOWERS WILL LINGER THROUGH
MULTIPLE DAYS, THE THERMODYNAMIC PROFILES DON'T LOOK TO SUPPORT SEVERE
POTENTIAL AS WE ARE SEEING 250-500 J/KG OF CAPE EACH AFTERNOON WITH
WEAK SHEAR. THESE VALUES WILL SUPPORT AIR MASS/POPCORN THUNDERSTORMS
WITH A FEW RUMBLES OF THUNDER AND SHORT LIVED LOCALIZED HEAVY RAIN.
CONSISTENT WITH A STATIONARY FRONT, TEMPERATURES WILL BE REMARKABLY
CONSISTENT OVER THE PERIOD. DAYTIME HIGHS IN THE WARMEST VALLEYS WILL
BE IN THE MID-80S DAILY WITH OVERNIGHT LOWS FALLING INTO THE MID-60S.
THE STATIONARY FRONT WILL FINALLY MOVE OFF AT THE END OF NEXT WEEK AS A
LOW PRESSURE WILL MOVE IN FROM THE SOUTHEASTERN US BRING MORE
ORGANIZATION TO THE THUNDERSTORMS AND THE POSSIBILITY OF STRONGER
CONVECTION.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
THROUGH 00Z MONDAY...INCREASING CLOUD COVER AND DIFFICULTY
MEETING CROSSOVER TEMPERATURES WILL LIMIT FOG CHANCES TONIGHT
WITH SOME LOW POTENTIAL TOWARDS DAYBREAK AT MPV/SLK. SOME
SOUTHERLY BREEZES WILL PICK UP AFTER 14Z SUNDAY, BUT GUSTS
FAVORED TO BE LESS THAN 20KTS. RAIN CHANCES INCREASE WEST TO
EAST, BUT MAINLY STAY IN NORTHERN NEW YORK 18-00Z; MSS COULD SEE
MVFR CIG/VIS AFTER 18Z WITH POTENTIAL FOR PERIODS OF MODERATE
TO HEAVY SHOWERS AND A FEW THUNDERSTORMS.
OUTLOOK...
SUNDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. LIKELY SHRA,
ISOLATED TSRA.
MONDAY: MAINLY MVFR, WITH LOCAL IFR POSSIBLE. LIKELY SHRA.
MONDAY NIGHT: VFR. SLIGHT CHANCE SHRA.
TUESDAY: VFR. NO SIG WX.
TUESDAY NIGHT: VFR. NO SIG WX.
WEDNESDAY: VFR. CHANCE SHRA, SLIGHT CHANCE TSRA.
WEDNESDAY NIGHT: VFR. CHANCE SHRA, SLIGHT CHANCE TSRA.
THURSDAY: MAINLY VFR, WITH AREAS MVFR POSSIBLE. CHANCE SHRA,
CHANCE TSRA.
CLIMATE
POSSIBLE HEAVY RAINFALL TOMORROW INTO MONDAY COULD APPROACH
DAILY RAINFALL RECORD LEVELS. BELOW ARE THE CURRENT DAILY
PRECIPITATION TOTAL RECORDS THAT MAY BE BROKEN AT OUR AREA
CLIMATE SITES.
RECORD PRECIPITATION:
AUGUST 2:
KMSS: 1.31/2020
BTV WATCHES/WARNINGS/ADVISORIES
VT...NONE.
NY...NONE.
WHAT HAS CHANGED...DANZIG
DISCUSSION...LANGBAUER/DANZIG
AVIATION...BOYD
CLIMATE...NWS BTV
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