019  
FXUS61 KBTV 300831  
AFDBTV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BURLINGTON VT  
431 AM EDT TUE MAY 30 2017  
   
SYNOPSIS
 
 
A LARGE UPPER-LEVEL LOW PRESSURE SYSTEM CENTERED ACROSS  
NORTHERN ONTARIO WILL REMAIN AS THE CONTROLLING WEATHER SYSTEM  
ACROSS THE NORTH COUNTRY OVER THE NEXT SEVERAL DAYS. SCATTERED  
SHOWERS WITH A FEW EMBEDDED THUNDERSTORMS ARE EXPECTED ACROSS  
THE AREA TODAY, AND AGAIN WEDNESDAY AFTERNOON. DRIER AIR  
FILTERING IN FROM THE WEST WEDNESDAY NIGHT SHOULD RESULT IN  
GENERALLY PRECIPITATION FREE CONDITIONS FOR THURSDAY. TEMPERATURES  
WILL REMAIN AT OR SLIGHTLY BELOW SEASONAL LEVELS THROUGH THE  
END OF THE WEEK.  
 

 
   
NEAR TERM /THROUGH WEDNESDAY/
 
 
AS OF 416 AM EDT TUESDAY...EARLY THIS MORNING, LOW STRATUS  
REMAIN IN PLACE FROM THE ADIRONDACKS EWD ACROSS THE SRN  
CHAMPLAIN VALLEY AND ALL OF CENTRAL/S-CENTRAL/ERN VT. WILL  
CONTINUE TO SEE SOME PATCHY DENSE FOG IN THE ADIRONDACKS AND  
EAST OF THE GREENS THROUGH SUNRISE OR SO. SHOULDN'T SEE ANY FOG  
IN THE CHAMPLAIN VALLEY, WITH SOUTHERLY GRADIENT FLOW AND  
CHANNELING EFFECTS KEEPING PBL WELL-MIXED LOCALLY (INCLUDING  
GUSTS TO 25 MPH EARLY THIS MORNING). EARLY AM LOWS EXPECTED TO  
RANGE FROM THE LOW-MID 50S IN THE CHAMPLAIN AND ST. LAWRENCE  
VALLEYS, TO THE MID 40S ACROSS THE NRN ADIRONDACKS AND ERN VT.  
KSLK, A LOCAL COOL SPOT, IS CURRENTLY 37F AT 08Z.  
 
FAIRLY ACTIVE WEATHER PATTERN NEXT 36 HOURS COURTESY OF  
CYCLONIC FLOW REGIME AND BELT OF 80-100KT SOUTHWESTERLY FLOW IN  
400-250MB LAYER EAST OF LARGE UPPER LOW ANCHORED OVER NORTHERN  
ONTARIO. LEFT EXIT REGION OF 250MB JET HAS BEEN SUPPORTING PRE-  
DAWN CONVECTIVE STORMS ACROSS FAR WRN NY AND PA AT 08Z, AND  
ANTICIPATE THIS FORCING SHIFTING NEWD INTO NRN NY BY 15Z OR SO.  
INSTABILITY IS COMPLICATED BY PREVAILING LOW STRATUS ACROSS THE  
NRN ADIRONDACKS EWD ACROSS MUCH OF VT AT 08Z. CONTINUED SOUTH  
WINDS WILL KEEP MUCH OF THESE LOW CLOUDS IN PLACE TODAY, WITH  
BEST SURFACE HEATING ACROSS THE NORTHERN SLOPES OF THE  
ADIRONDACKS AND ST. LAWRENCE COUNTY. SHOULD SEE SOME COMBINATION  
OF ELEVATED AND/OR SURFACE-BASED CAPE AROUND 500 J/KG ACROSS  
OUR WESTERN ZONES, ALLOWING FOR A FEW THUNDERSTORMS TO TAKE  
PLACE. STRONG DEEP-LAYER SHEAR (SFC-6KM VALUES OF 50-60KT) MAY  
SUPPORT SOME ORGANIZATION, BUT WEAK CAPE MAY MEAN ENVIRONMENT  
SHEARS MUCH OF THE CONVECTION APART. WITH DEWPOINTS ONLY IN THE  
LOW 50S, NOT EXPECTING MUCH SEVERE POTENTIAL. A FEW  
STRONGER/FAST MOVING CORES MAY CONTAIN BRIEF HEAVY  
DOWNPOURS/GUSTY WINDS AND LIGHTNING, AND HAVE MADE MENTION OF  
THIS IN THE MORNING HAZARDOUS WEATHER OUTLOOK. STRONGEST STORMS  
LIKELY ACROSS ST. LAWRENCE COUNTY. AS ACTIVITY SHIFTS EWD INTO  
VT, APPEARS INSTABILITY WILL BE INCREASINGLY ELEVATED PROVIDED  
STRATUS LAYER HOLDS. INDICATED CHANCE TSTMS S-CENTRAL VT AND  
NORTHERN NY, WITH SLIGHT CHANCE FURTHER NORTH AND EAST GIVEN  
EXPECTED INSTABILITY FIELDS. POPS INCREASE TO LIKELY THIS  
AFTERNOON WITH BEST LARGE-SCALE FORCING VIA JET DYNAMICS AND  
HEIGHT FALLS. WILL SEE A QUARTER TO HALF INCH OF RAINFALL IN  
MANY SPOTS, BUT WITH MUCH OF THAT FALLING IN A 1-2 HR WINDOW  
WITH THE SHOWER/THUNDERSTORM ACTIVITY.  
 
WINDS WILL CONTINUE MODERATELY STRONG FROM THE SOUTH GIVEN  
P-GRADIENT, WITH GUSTS UP TO 30 MPH IN THE CHAMPLAIN VALLEY WITH  
LOCALIZED CHANNELING EFFECTS. LAKE WIND ADVISORY CONTINUES ON  
LAKE CHAMPLAIN WITH SOUTH WINDS INCREASING TO 20-30KTS LATER  
THIS MORNING PER NAM-NEST AND BTV-2KM AND 4KM WRF RUNS.  
 
TEMPERATURES WILL REACH THE UPPER 60S IN THE CHAMPLAIN VALLEY,  
AND LOWER 70S IN THE ST. LAWRENCE VALLEY. THICKER STRATUS EAST  
OF THE GREEN MTNS SHOULD HOLD TEMPS IN THE LOW-MID 60S FOR AFTN  
HIGHS.  
 
ANTICIPATE LINGERING SHOWERS EXITING ACROSS FAR ERN/SERN VT  
DURING THE 00-03Z PERIOD TONIGHT, LEAVING THE BALANCE OF THE  
NIGHT DRY ACROSS THE NORTH COUNTRY. PBL REMAINS WELL MIXED WITH  
VARIABLY CLOUDY CONDITIONS CONTINUING. SHOULD PRECLUDE FOG AND  
KEEP OVERNIGHT LOWS WARM, MOSTLY IN THE 50S (LOCALLY 58F AT  
BTV).  
 
YET ANOTHER SHORTWAVE TROUGH PIVOTS AROUND PARENT UPPER LOW ON  
WEDNESDAY, TRANSLATING ENEWD ACROSS THE NORTH COUNTRY WEDNESDAY  
AFTERNOON. A PRE-FRONTAL SFC TROUGH DEVELOPING ACROSS THE ERN  
SLOPES OF THE ADIRONDACKS SHOULD SERVE AS A FOCUS FOR CONVECTIVE  
INITIATION, WITH SBCAPE OF 500-1000 J/KG POSSIBLE ACROSS MUCH OF  
VT PROVIDED THERE IS SUFFICIENT CLEARING/INSOLATIONAL HEATING  
DURING THE LATE MORNING/EARLY AFTERNOON HRS. THUS, POPS RAMP UP  
TO 70-80% ONCE AGAIN WEDNESDAY AFTN, WITH CHANCE TSTMS MENTIONED  
FROM THE ERN SLOPES OF THE ADIRONDACKS EWD ACROSS VT AS ACTIVITY  
SHIFTS EWD. ACTIVITY AGAIN EXPECTED TO BE GENERALLY SUB-SEVERE  
GIVEN LIMITED DEWPOINTS/INSTABILITY, BUT LOCALIZED GUSTY  
WINDS/HEAVY DOWNPOURS ARE POSSIBLE. HIGHS ON WEDNESDAY EXPECTED  
IN THE UPR 60S TO LOWER 70S.  
 

 
   
SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/
 
 
AS OF 352 AM EDT TUESDAY...FOR THE FIRST HALF OF WEDNESDAY  
EVENING WE'LL LIKELY STILL BE DEALING WITH SOME SCATTERED  
SHOWERS ACROSS EASTERN PORTIONS OF THE FORECAST AREA, BUT AS  
DIURNAL COOLING BEGINS WE SHOULD SEE THE SHOWERS DIMINISH. THERE  
WILL BE A MORE PRONOUNCED THERMAL GRADIENT WITH THE SYSTEM ON  
WEDNESDAY EVENING THAN TUESDAY EVENING SO OVERNIGHT LOWS SHOULD  
DROP TO MORE NORMAL TEMPS IN THE UPPER 40S TO LOW 50S.  
 
UNSETTLED WEATHER CONTINUES ON THURSDAY AS THERE WILL LIKELY BE  
SOME SHOWERS ENTERING THE AREA LATE IN THE AFTERNOON OVER THE  
SAINT LAWRENCE VALLEY. THURSDAY MAY BE THE DRIEST DAY OF THE  
PERIOD AS WE COULD SEE SOME BREAKS IN THE CLOUDS THROUGH THE  
MORNING AND INTO THE AFTERNOON. EXPECT JUST BELOW NORMAL TEMPS  
IN THE UPPER 60S FOR HIGHS ON THURSDAY AND LOWS RIGHT AROUND  
NORMAL IN THE UPPER 40S TO LOW 50S.  
 

 
   
LONG TERM /FRIDAY THROUGH MONDAY/
 
 
AS OF 352 AM EDT TUESDAY...I'LL KEEP WITH CONSISTENCY HERE AS  
THERE REALLY ISN'T MUCH CHANGE FROM THE PREVIOUS FORECAST  
THINKING. THE PATTERN FOR THE EXTENDED PERIOD HASN'T CHANGED IN  
DAYS, LARGELY CONTROLLED DOMINATED BY AN UPPER LEVEL LOW THAT IS  
BLOCKED BY A STRONG NORTHERN ATLANTIC LOW PRESSURE SYSTEM.  
WHILE EVERY DAY HAS A CHANCE FOR SHOWERS, THE BEST CHANCE LOOKS  
TO BE FRIDAY AFTERNOON AND EVENING AS A COLD FRONT WILL SWING  
THROUGH. THE UPPER LEVEL LOW GRADUALLY EXITS TO OUR EAST OVER  
THE WEEKEND AND THAT IS WHERE THE FORECAST GETS A BIT MORE  
DIFFICULT AS THE SPREAD IN MODELS BECOMES QUITE LARGE. I'VE  
DISCOUNTED THE DRIER GFS FOR SUNDAY'S FORECAST AS IT'S THE  
OUTLIER BETWEEN THE GEM/EC WHICH BRING A CUT OFF LOW PRESSURE  
SYSTEM THROUGH THE NORTH COUNTRY. THIS MAKES MORE SENSE BECAUSE  
THAT LOW WOULD BE THE DRIVING FORCE TO PUSH OUT THE PERSISTENT  
UPPER LEVEL LOW THAT BROUGHT THE CONTINUOUS ROUNDS OF SHOWERS  
THROUGH THE WEEK. TEMPS THROUGH THE PERIOD SHOULD BE VERY  
SEASONAL WITH HIGHS IN THE MID 60S TO LOW 70S, AND LOWS IN THE  
MID 40S TO LOW 50S.  
 

 
   
AVIATION /08Z TUESDAY THROUGH SATURDAY/
 
 
THROUGH 12Z WEDNESDAY....HIGHLY VARIABLE AVIATION WEATHER  
CONDITIONS EXPECTED ACROSS THE AREA OVER THE NEXT 24 HOURS. PRE-  
DAWN CONDITIONS INCLUDE MVFR CEILINGS AT BTV/RUT OWING TO  
STRATUS LAYER, VFR CONDITIONS AT PBG/MSS WITH JUST PASSING MID-  
LEVEL CLOUDS, AND IFR CONDITIONS AT SLK/MPV OWING TO A  
COMBINATION OF FOG AND VERY LOW STRATUS CONDITIONS. HIR TRRN  
OBSCD GENERALLY THROUGH 15-16Z THIS MORNING, AND MAY REMAIN  
OBSCD THRU MOST OF THE DAYLIGHT HRS ACROSS CENTRAL AND ERN VT.  
MAY SEE MVFR CEILINGS HOLD IN ACROSS MUCH OF CENTRAL/ERN VT  
DURING THE DAYLIGHT HRS, WITH BETTER CHANCES FOR VFR CONDITIONS  
DEVELOPING FROM THE CHAMPLAIN VALLEY WWD. SHOULD SEE A BROKEN  
LINE OF SHOWERS AND A FEW EMBEDDED TSTMS DEVELOP ACROSS NRN NY  
LATE THIS MORNING, WITH ACTIVITY SHIFTING EWD ACROSS VERMONT  
THIS AFTERNOON. BEST CHANCES FOR TSTMS AT THE TAF LOCATIONS WILL  
BE AT SLK/RUT, WITH MORE STABLE LOW-LEVEL CONDITIONS DUE TO  
CLOUD COVER EXPECTED TO THE NORTH AND EAST. WINDS WILL BE GUSTY  
AT TIMES FROM THE SOUTH. AT BTV, SHOULD SEE SOUTH WINDS 15-20KTS  
WITH GUSTS UP TO 25KT THRU 21Z TODAY. SHOULD SEE REDEVELOPMENT  
OF LOW STRATUS TONIGHT, WITH PERIODS OF MVFR CEILINGS AND  
LOCALIZED IFR ONCE AGAIN AT SLK/MPV. WINDS TONIGHT GENERALLY  
REMAIN OUT OF THE SOUTH AT 5-10KTS.  
 
OUTLOOK...  
 
WEDNESDAY: VFR. BREEZY. CHANCE SHRA...CHANCE TSRA.  
WEDNESDAY NIGHT: VFR. CHANCE SHRA...CHANCE TSRA.  
THURSDAY: VFR. SLIGHT CHANCE SHRA.  
THURSDAY NIGHT: VFR. SLIGHT CHANCE SHRA.  
FRIDAY: VFR/MVFR. LIKELY SHRA.  
FRIDAY NIGHT: VFR. CHANCE SHRA.  
SATURDAY: VFR. CHANCE SHRA.  
 

 
   
MARINE
 
 
LAKE WIND ADVISORY REMAINS IN EFFECT FOR SOUTH WINDS 15-25KTS  
EARLY THIS MORNING, INCREASING TO 20-30 KTS LATE THIS MORNING  
THROUGH THIS AFTERNOON. SHOULD SEE WAVES BUILD TO 3-5 FEET,  
HIGHEST ACROSS THE NORTHERN PORTION OF THE BROAD LAKE TO NEAR  
THE SOUTH FACING SHORES OF GRAND ISLE. SHOULD SEE WINDS REMAIN  
FROM THE SOUTH 15-25 KTS TONIGHT.  
 

 
   
BTV WATCHES/WARNINGS/ADVISORIES
 
 
VT...NONE.  
NY...NONE.  
 

 
 

 
SYNOPSIS...BANACOS  
NEAR TERM...BANACOS  
SHORT TERM...DEAL  
LONG TERM...DEAL  
AVIATION...BANACOS  
MARINE...TEAM BTV  
 
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