Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 132348 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 748 PM EDT SUN APR 13 2014 .SYNOPSIS...
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OTHER THAN A FEW SHOWERS ACROSS THE FAR NORTH AND WEST OVERNIGHT INTO MONDAY...MILD AND MAINLY DRY WEATHER IS EXPECTED ACROSS THE REGION. A STRONG COLD FRONT WILL APPROACH AND CROSS THE AREA LATER MONDAY NIGHT INTO TUESDAY WITH WIDESPREAD RAINFALL AND A CHANCE OF AN ISOLATED STORM. SHARPLY COLDER AIR FOLLOWS THE FRONT WITH RAIN CHANGING TO LIGHT SNOW OR SNOW SHOWERS BEFORE ENDING TUESDAY NIGHT. A MAINLY SUNNY BUT CHILLY DAY IS EXPECTED ON WEDNESDAY BEFORE TEMPERATURES MODERATE BY LATE WEEK.
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&& .NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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AS OF 748 PM EDT SUNDAY...COMPOSITE RADAR LOOP SHOWING SHOWERS ALONG WITH SOME EMBEDDED THUNDERSTORMS ACROSS SOUTHWEST QUEBEC AND SOUTHEAST ONTARIO...WEST OF THE SAINT LAWRENCE VALLEY AT THIS TIME. RADAR TRENDS SHOWING THIS ACTIVITY MOVING NORTHEAST AND STAYING IN CANADA AT THIS TIME. MODELS HINTING THAT SOME OF THIS SHOWER ACTIVITY MAY MOVE INTO THE NORTHERN PORTION OF THE FORECAST AREA OVERNIGHT...SO WILL CONTINUE CHANCE POPS FOR SHOWERS ACROSS THE NORTHERN FORECAST ZONES. OTHERWISE...HAVE POPULATED THE GRIDS WITH THE LATEST SURFACE OBSERVATIONS. RIVER GAGES ON THE AUSABLE RIVER IN NORTHERN NEW YORK APPROACHING FLOOD STAGE AT THIS TIME. THIS RISE IN THE RIVER IS DUE MAINLY TO SNOW MELT ACROSS THE ADIRONDACKS. WILL CONTINUE TO MONITOR THIS CLOSELY. PREVIOUS DISCUSSION FROM 424 PM EDT SUNDAY...CHANGEABLE CONDS CONTINUE ACROSS THE FORECAST AREA LATE THIS AFTERNOON AS STRONG WARM FRONT CONTINUES TO LIFT SLOWLY NORTH AND EAST TOWARD THE INTL BORDER PER LATEST SATELLITE/SFC OBSERVATIONS. TEMPERATURES MARKEDLY VARIABLE SOUTHWEST TO NORTHEAST AS OF 300 PM...RANGING FROM THE 60S INTO THE LOWER 70S IN MOST PLACES WEST OF THE GREENS...TO THE 50S AND EVEN 40S FURTHER NORTH AND EAST...ESP NORTHEASTERN VT. AS SOUTHWESTERLY FLOW CONTINUES TO BUILD/DEEPEN OVERNIGHT...TEMPERATURES SHOULD HOLD ON THE MILD SIDE AND HAVE LEANED HEAVILY TOWARD THE RAW 12Z BTV4 MODEL T OUTPUT...SUGGESTING NEAR STEADY READINGS IN MOST PLACES WITH MAINLY 50S EXPECTED...THOUGH SOME 40S NC/NE VT. MESOSCALE MODELS REMAIN INSISTENT THAT A CLUSTER OF SHOWERS/ISOLD STORMS MAY FORM ALONG THE SOUTHERN EDGE OF THE DEEPER 850-500MB FLOW JUST SOUTH OF THE WARM FRONT THIS EVENING ALONG OUR INTL BORDER COUNTIES...AND GIVEN CONSISTENCY AMONG THESE SOLNS I`VE MAINTAINED TOKEN CHC POPS IN THESE LOCATIONS ACCORDINGLY. THIS IS A CONDITIONAL FCST HOWEVER...AND TO BE HONEST MY CONFIDENCE LEVEL OF SOMETHING ACTUALLY DEVELOPING IS BELOW 50% BASED OFF LATEST MOVEMENT OF ERN LAKES SHORTWAVE AND CANADIAN RADAR TRENDS. OF MORE CERTAINTY WILL BE MAINLY DRY WEATHER ACROSS OUR CENTRAL AND SOUTHERN COUNTIES WHICH WILL BE FURTHER REMOVED FROM DEEPER MOISTURE/DYNAMICAL FORCING.
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&& .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... AS OF 424 PM EDT SUNDAY...BY TOMORROW THE FORECAST AREA IS FIRMLY ENTRENCHED INTO MILD/WARM SOUTHWESTERLY FLOW AS WARM FRONT WILL HAVE LIFTED WELL NORTH INTO SOUTHERN CANADA AND SURFACE COLD FRONT WILL REMAIN FAR TO OUR WEST ACROSS THE CENTRAL GREAT LAKES STATES. TYPICAL WITH EARLY SEASON BERMUDA UPPER RIDGING...THE H5 FLOW IS SOMEWHAT "DIRTY" WITH VARIABLE CLOUDS AND EMBEDDED WEAK MID LEVEL SHORTWAVE ENERGY BUNDLES RIDING NORTHEAST IN THE DEEP SOUTHWESTERLY FLOW ALOFT. ENOUGH CONFIDENCE HOWEVER THAT AT LEAST SOME OF THIS ENERGY MAY SPARK A FEW/SCT SHOWERS ACROSS OUR ST LAWRENCE VALLEY/WRN DACK COUNTIES BY THE AFTERNOON HOURS AND HAVE MAINTAINED SOLID CHC TO LOW LIKELY POPS IN THESE AREAS ACCORDINGLY. FURTHER EAST DRY WEATHER EXPECTED WITH A HIGHER PERCENTAGE OF SUNSHINE EXPECTED. TEMPERATURES VERY MILD TO WARM...AND CONSIDERING BACK-TRAJECTORY ANALYSIS AT 500-1000M SUGGESTS SOURCE AIR WILL COME FROM THE GA/SC AREA TODAY...HIGHS IN THE 70S FOR MOST AREAS APPEARS REASONABLE...WITH SOLID 70S TO PERHAPS NEAR 80 IN A FEW SPOTS IN THE CHAMPLAIN AND ST LAWRENCE VALLEYS. RECORD HIGHS FOR THE DATE MAINLY IN THE LOWER 80S SO IT APPEARS THEY`LL BE JUST OUT OF REACH. IT WILL ALSO TREND QUITE BREEZY THROUGH THE DAY AND WITH DEEPENING PBL MIXING SOUTH/SOUTHWESTERLY GUSTS INTO THE 25 TO 35 MPH RANGE IN MOST SPOTS LOOKS ON TRACK. COULD SEE GUSTS A TAD HIGHER ABOVE 40 MPH IN FAVORED LOCATIONS OF THE CHAMPLAIN AND ST LAWRENCE VALLEYS AND IF FUTURE MODEL DATA REMAINS CONSISTENT...A WIND ADVISORY MAY BE NEEDED ACROSS SOME OF THIS AREA ON MONDAY. THEN CONTINUED BREEZY AND MILD MONDAY NIGHT UNDER CONTINUED SOUTH FLOW. LOWS AGAIN MAINLY IN THE 50S...WITH A FEW SPOTS IN THE CHAMPLAIN VALLEY (BTV FOR EXAMPLE) LIKELY NOT FALLING BELOW THE 60F MARK. AFOREMENTIONED STRONG COLD FRONT WILL BE SLOWLY EDGING EAST FROM THE EASTERN GREAT LAKES STATES OVERNIGHT...WITH PRECIPITATION CHANCES INCREASING STEADILY ACROSS OUR NRN NY COUNTIES AS THE NIGHT WEARS ON. COULD SEE A FEW STRAY SPRINKLES/LIGHT SHOWERS FURTHER EAST INTO VERMONT LATE...BUT AT THIS POINT I FEEL MOST AREAS WILL REMAIN MAINLY DRY AT THIS POINT...ESP EASTERN VT. STRONG COLD FRONT THEN PUSHES ACROSS THE AREA DURING THE DAYLIGHT HOURS ON TUESDAY WITH WIDESPREAD MODERATE TO LOCALLY HEAVY RAINFALL EXPECTED. INCREDIBLY SHARP THERMAL GRADIENT E-W ACROSS THE BOUNDARY...AND HAVE AGAIN LEANED HEAVILY TOWARD RAW BTV4 T PROGS...SUGGESTING EARLY HIGHS IN THE 60S...CRASHING SHARPLY BY DAYS END INTO THE 30S WEST AND 40S EAST. INDEED...TEMPS MAY FALL AS MUCH AS 15 DEG IN THE FIRST HOUR BEHIND FROPA IN ANY GIVEN AREA. AS MUCH COLDER AIR WORKS IN ALOFT...PCPN WILL TRANSITION TO A MIX OF RAIN/SNOW...THEN A WET SNOW/SHSN BY LATE AFTERNOON ACROSS NRN NY...AND EARLY EVENING INTO VT BEFORE ENDING BY MIDNIGHT OR SHORTLY THEREAFTER AS FRONT CLEARS EAST. SOME MINOR ACCUMULATIONS WILL BE LIKELY IN THE NORTHERN MOUNTAINS WHERE I`VE SUGGESTED 1-3 INCH ACCUMULATIONS ABOVE 1000 FEET...AND LOCALLY TO NEAR 5 INCHES AT SUMMIT LEVEL. LESSER AMOUNTS IN THE DEEPER VALLEY FLOORS...BUT EVEN HERE A QUICK/WET DUSTING-INCH WILL BE POSSIBLE. QUITE A CHANGE FROM MONDAY`S WARM TEMPERATURES INDEED! BY LATER TUESDAY NIGHT CONDITIONS TREND DRY AS DEEPER MOISTURE PULLS WELL EAST AND DEEP LAYER HIGH PRESSURE BUILDS IN FROM THE GREAT LAKES STATES. AS SKIES TREND CLR/PTLY CLOUDY OVERNIGHT...LOWS WILL TREND QUITE CHILLY...BOTTOMING OUT IN THE 20S WITH A FEW UPPER TEENS POSSIBLE IN COLDER SPOTS IN THE NORTHERN MOUNTAINS. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 330 PM EDT SUNDAY...MUCH QUIETER WX ANTICIPATED FOR WEDS THRU FRIDAY AS SFC HIGH PRES BUILDS DIRECTLY OVERHEAD. STRONG CAA ON WEDS WL RESULT IN MUCH BLW NORMAL TEMPS WITH PROGGED 85H TEMPS BTWN -10C AND -12C. THESE TEMPS WITH NORTHWEST FLW WL SUPPORT HIGHS U20S/L30S MTNS TO UPPER 30S TO LOWER 40S VALLEYS...WITH READINGS NEAR VSF AT 45F ON WEDS. EXPECTING VERY COLD TEMPS ON WEDS NIGHT INTO THURSDAY WITH A COUPLE OF RECORD LOW TEMPS POSSIBLE...ESPECIALLY AT MSS. THE RECORD LOW AT MSS IS 23F AND 18F AT BTV/MPV...THINKING AROUND 20F AT MSS/MPV AND PROBABLY THE MID 20S AT BTV. SEVERAL OF THE COLDER MTN VALLEYS WL PROBABLY DROP INTO THE MID/UPPER TEENS BY THURS MORNING. SFC HIGH PRES SHIFTS INTO NORTHERN NEW ENGLAND ON THURS INTO FRIDAY WITH A SLOW WARMING TREND ANTICIPATED. PROGGED 85H TEMPS BTWN -2C AND -4C ON THURS SUPPORT HIGHS BACK INTO THE 40S MTNS AND 50S VALLEYS WITH ANOTHER 4 TO 6 DEGREES WARMER ON FRIDAY. THE NEXT CHC FOR SHOWERS WL BE SAT AND SUNDAY OF NEXT WEEKEND. STILL PLENTY OF UNCERTAINTY ON TIMING OF SYSTEM...MAGNITUDE OF MID/UPPER LVL TROF...AND TRACK OF SFC LOW PRES. BOTH GFS/ECMWF SHOW THE POTENTIAL FOR SHOWERS...BUT DISAGREE ON STRENGTH OF CLOSED 5H/7H CIRCULATION AND AMOUNT OF INTERACTION WITH SOUTHERN STREAM ENERGY/MOISTURE...ESPECIALLY ON SUNDAY. GFS IS MUCH STRONGER WITH NORTHERN STREAM ENERGY AND DEVELOPMENT OF DEEP TROF...WHILE ECMWF SHOWS MOST OF THE ENERGY/MOISTURE STAYING SOUTH OF OUR CWA AND MUCH WEAK SFC COLD FRNT AND NORTHERN STREAM S/W. WL MENTION CHC POPS ATTM WITH NEAR NORMAL TEMPS AND FINE TUNE AS EVENT BECOMES CLOSER. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... THROUGH 00Z TUESDAY...WAVY WARM FRONT WITH ASSOCIATED NORTHEAST- MOVING SHOWERS/EMBEDDED THUNDER ACROSS OTTAWA VALLEY/WESTERN EDGE OF SAINT LAWRENCE VALLEY. EXPECT SHOWERS TO AFFECT MSS THROUGH 05Z. CAN`T RULE OUT ISOLATED THUNDER HERE AS WELL. GUIDANCE APPEARS TO BE OVERDOING LOW CEILINGS GIVEN BOTH THE OVERALL SYNOPTIC PATTERN OF BUILDING HEIGHTS ALOFT AS WELL AS EVIDENCE IN UPSTREAM OBS WHICH SHOW MVFR/IFR CEILINGS REMAINING ON THE COLD SIDE OF THE BOUNDARY. THUS HAVE OPTED FOR PRIMARILY VFR CONDITIONS OVERNIGHT FOR THE REST OF THE TAFS. ONE EXCEPTION IS AT LEAST MVFR VISIBILITY MIST IN AREAS WHERE WINDS DECOUPLE AND/OR SHOWERS DEVELOP OVERNIGHT. THIS POTENTIAL MOST LIKELY AT SLK AND ALSO AT MSS. WINDS TO OTHERWISE REMAIN SOUTH AROUND 10-12 KTS. STILL CONTENDING WITH AREAS OF LLWS AT MSS GIVEN PERSISTENT NE WINDS THERE SHIFTING TO SSW 35-40 KTS AT 2KFT PER TYX VAD. EXPECT VFR CONDITIONS FOR MONDAY WITH GUSTY SOUTH/SOUTHWEST WINDS PARTICULARLY AT MSS. GUSTS COULD REACH UP TO 30 KTS THERE. COLD FRONT APPROACHES MSS LATE IN THE PERIOD WITH VCSH INDICATED THERE AFTER 20Z...BUT OTHERWISE LOOK FOR LOWERING CEILINGS DURING THAT SAME PERIOD OF TIME FOR THE REST OF THE TAFS. OUTLOOK 00Z TUESDAY THROUGH THURSDAY... A SLOW MOVING COLD FRNT APPROACHES OUR TAF SITES BY 12Z TUESDAY WITH OCCASIONAL SHOWERS DEVELOPING...ALONG WITH THE POTENTIAL FOR A FEW EMBEDDED LOW TOP THUNDERSTORMS. IN ADDITION...GUSTY OUTFLOW WINDS WL BE POSSIBLE ASSOCIATED WITH THE LINE OF SHOWERS...WITH A SHARP WIND SHIFT TO THE WEST/NORTHWEST EXPECTED BTWN 15Z-21Z TUESDAY ACRS OUR TAF SITES. VFR WITH MVFR CONDITIONS ARE LIKELY WITH THE FROPA PRECIP. CANNOT RULE OUT A 15 TO 30 MINUTE PERIOD OF IFR IN THE HEAVIEST CONVECTION SHOWERS WITH VIS <3SM. RAIN CHANGES TO SNOW SHOWERS BY 21Z AT MSS/SLK AND BY 00Z WEDS AT PBG/BTV/MPV/RUT WITH A PERIOD OF IFR VIS/CIGS POSSIBLE ON TUES EVENING. SFC HIGH PRES WITH CLRING EXPECTED ON WEDS INTO THURSDAY. && .HYDROLOGY... AS OF 424 PM EDT SUNDAY...FLOOD WATCH CONTINUES FOR THE ENTIRE FORECAST AREA THROUGH WEDNESDAY EVENING FOR EXPECTED RAINFALL AND WIDESPREAD SNOWMELT. RIVERS AND STREAMS CONTINUE TO RUN SEASONABLY HIGH AS OF MID-AFTERNOON AS THIS MORNING`S RAINFALL AND CONTINUED MODEST SNOWMELT CONTRIBUTE TO SURFACE RUNOFF. WHILE SOME MINOR LOWLAND FLOODING WILL CONTINUE THROUGH MONDAY NIGHT...THE PRIMARY FOCUS FOR MORE WIDESPREAD FLOODING WILL OCCUR TUESDAY AFTERNOON INTO WEDNESDAY MORNING DUE TO THE COMBINATION OF VERY MILD TEMPERATURES AND HEAVIER RAINFALL. AT THIS TIME...BASIN-AVG QPF WILL GENERALLY RANGE FROM 1 TO 1.5 INCHES DURING THE MONDAY NIGHT THROUGH TUESDAY EVENING TIME FRAME. WHILE NOT EXCESSIVELY HEAVY...THESE RAINFALL AMOUNTS ALONG WITH CONTINUED SNOWMELT SHOULD BE MORE THAN ENOUGH TO PRODUCE SHARP RISES ON MOST AREA STREAMS AND RIVERS...IN SOME CASES INTO MINOR FLOOD BY TUESDAY AFTERNOON INTO TUESDAY NIGHT. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...FLOOD WATCH THROUGH WEDNESDAY EVENING FOR VTZ001>012-016>019. NY...FLOOD WATCH THROUGH WEDNESDAY EVENING FOR NYZ026>031-034-035- 087. && $$ SYNOPSIS...JMG NEAR TERM...JMG/WGH SHORT TERM...JMG LONG TERM...TABER AVIATION...TABER/LOCONTO HYDROLOGY...JMG

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