280  
FXUS61 KBTV 171132  
AFDBTV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BURLINGTON VT  
732 AM EDT WED OCT 17 2018  
   
SYNOPSIS
 
 
THE COLDEST AIRMASS OF THIS FALL SEASON IS POISED TO MOVE ACROSS THE  
NORTH COUNTRY TODAY WITH MAINLY VALLEY RAIN SHOWERS AND HIGH  
ELEVATION SNOW SHOWERS. HOWEVER, AS THE ATMOSPHERE COOLS ALOFT THIS  
AFTERNOON AND INSTABILITY INCREASES SOME CONVECTIVE SHOWERS WITH  
EMBEDDED ICE PELLETS ARE POSSIBLE, EVEN IN THE VALLEYS, BUT LITTLE  
ACCUMULATION IS EXPECTED. TONIGHT BRISK NORTHWEST UPSLOPE WINDS WILL  
PRODUCE SCATTERED MOUNTAIN SNOW SHOWERS, ALONG WITH CHILLY OVERNIGHT  
LOWS IN THE 20S TO LOWER 30S. WINDCHILL VALUES WILL FEEL MUCH  
COLDER. A COLD AND BREEZY THURSDAY IS EXPECTED WITH INTERVALS OF  
CLOUDS AND SUN.  
 

 
   
NEAR TERM /THROUGH THURSDAY/
 
 
AS OF 723 AM EDT WEDNESDAY...CRNT RADAR SHOWS LIGHT RAIN ACROSS  
PARTS OF NORTHERN NY AND HIGHER TRRN OF VT. I ASSUME SOME SNOW  
IS FALLING NEAR THE SUMMITS AS WHITEFACE AND MT MANSFIELD TEMP  
IS CURRENTLY 30 DEGREES. NO SIGNIFICANT CHANGES TO FORECAST WAS  
MADE WITH THIS UPDATE, AS POPS/TEMPS AND WINDS LOOKED GOOD.  
 
PREVIOUS DISCUSSION BELOW:  
WATER VAPOR SHOWS DEEPENING MID/UPPER TROF ACROSS THE GREAT  
LAKES WITH EMBEDDED 5H VORT OVER NORTHERN MI, WHILE FAST  
CONFLUENT FLOW ALOFT PREVAILS ACROSS OUR FA. THIS POTENT 5H VORT  
IS ALIGNED WITH A SFC COLD FRONT LOCATED OVER THE CENTRAL GREAT  
LAKES AND WILL IMPACTS OUR CWA WITH A PERIOD OF SHOWERS TODAY.  
IN ADDITION, ALIGNED SOUTHWEST SFC TO 850MB FLOW AHEAD OF  
APPROACHING BOUNDARY IS HELPING TO ADVECT 925MB TO 775MB LAKE  
ENHANCED MOISTURE INTO THE WESTERN DACKS/SOUTHERN SLV THIS  
MORNING. HAVE CONTINUED TO MENTION LIKELY POPS FROM DACKS INTO  
NORTHERN GREENS NEAR JAY PEAK TO COVER THIS PRECIP. RAP PROGGED  
850MB TEMP ANALYSIS PLACES 0C CONTOUR ACROSS OUR CENTRAL CWA, SO  
ANTICIPATE SNOW LEVELS NEAR SUMMITS THIS MORNING.  
 
THIS AFTERNOON/EVENING PROFILES BECOME INTERESTING, AS RAPID COOLING  
ALOFT OCCURS AND VERY STEEP LOW LEVEL LAPSE RATES DEVELOP WHEN  
POTENT ENERGY ARRIVES. SOUNDINGS SHOW SFC TO 750MB LAPSE RATES  
>9.0 C/KM, WITH UP TO 100 J/KG OF CAPE, INDICATING THE PRECIP  
WILL BE CONVECTIVE IN NATURE. ALSO, SUPPORTING THIS THINKING IS  
PROGGED HIGH COMPOSITE REFLECTIVITY FIELDS OFF THE RAP/HRRR/NAM  
3KM. THINKING QUICK CONVECTIVE BURST OF SCATTERED SHOWERS THIS  
AFTN/EVENING WILL HAVE THE POTENTIAL TO PRODUCE SOME POCKETS OF  
ICE PELLETS AS COLD AIR FROM ALOFT IS TRANSFERED TO THE SURFACE  
IN THE PRECIP DOWNDRAFTS, EVEN IN THE VALLEYS. ANY ACCUMULATIONS  
WILL BE MINIMAL AND PRECIP WILL BE SCATTERED IN NATURE.  
 
PROGGED 850MB TEMPS NEAR 0C SUPPORT HIGHS UPPER 30S TO LOWER 50S  
DEPENDING UPON ELEVATION. BY 00Z TONIGHT 925MB TEMPS QUICKLY DROP  
BELOW 0C, WHILE 850MB TEMPS ARE BTWN -3C AND -6C, SUPPORTING  
LOWERING SNOW LEVELS AS STRONG LOW LEVEL COLD AIR ADVECTION  
CONTINUES ON BRISK NORTHWEST WINDS. THINKING SNOW LEVELS WILL BE  
AROUND 1500 FEET BY 00Z AND NEAR THE VALLEY FLOOR BY 06Z, BUT  
DEEP LAYER MOISTURE IS QUICKLY ERODING AS DRIER AIR DEVELOPS ON  
850MB WINDS OF 35 TO 45 KNOTS. SOUNDING SUPPORT GOOD MIXING  
OVERNIGHT WITH SFC WIND GUSTS OF 30 TO 35 KNOTS LIKELY, GIVEN  
THE MOMENTUM TRANSFER VALUES. THINKING AREAL COVERAGE OF PRECIP  
BECOMES CONFINED TO THE TRRN AND DOWNWIND, GIVEN THE UNBLOCKED  
FLOW.  
 
EXPECT AS 850MB TEMPS COOL TO NEAR -11C BY 12Z THURSDAY INTERACTS  
WITH VERY WARM LAKE CHAMPLAIN WATER TEMPS OF 13C, MODERATE TO  
EXTREME INSTABILITY WILL DEVELOP TO HELP ENHANCE CLOUDS AND SOME  
LIGHT PRECIP ALONG AND DOWNWIND OF THE GREEN MOUNTAINS LATE TONIGHT  
INTO THURSDAY MORNING. HAVE INCREASED CLOUDS AND MENTIONED SCHC TO  
CHC POPS IN THE MOUNTAINS OF VT OVERNIGHT WITH SOME LIGHT SNOW  
ACCUMULATION POSSIBLE. THINKING TOTAL SNOW ACCUMULATION OF A DUSTING  
TO 2 INCHES WITH HIGHEST VALUES TOWARD THE SUMMITS FROM MT MANSFIELD  
TO JAY PEAK. LITTLE ACCUMULATION IS EXPECTED IN THE VALLEYS. LOWS  
TONIGHT MID TEENS SUMMITS WITH WIND CHILL VALUES BELOW 0F TO LOW/MID  
30S CHAMPLAIN VALLEY. A FREEZE WARNING MAYBE NEEDED IN THE CPV,  
WHERE THE GROWING SEASON IS STILL ONGOING. DAYSHIFT CAN MAKE FINAL  
DECISION.  
 
THURSDAY WILL FEATURE MUCH BELOW NORMAL TEMPS AS DEEP MID/UPPER  
LEVEL TROF PREVAILS ACROSS THE NORTHEAST CONUS. THE COMBINATION OF  
BUILDING 1034MB HIGH PRES OVER THE OHIO VALLEY AND DEPARTING LOW  
PRES OVER NORTHERN MAINE WILL CREATE A BRISK NORTHWEST WIND ACROSS  
OUR CWA. THIS COMBINED WITH PROGGED 850MB TEMPS BTWN -9C AND -11C,  
SUPPORT HIGHS ONLY IN THE UPPER 20S/LOWER 30S MOUNTAIN TOWNS TO  
LOWER 40S NEAR LAKE CHAMPLAIN. SOME LEFTOVER FLURRIES/MOUNTAIN SNOW  
SHOWERS ARE POSSIBLE DOWNWIND OF LAKE CHAMPLAIN.  
 

 
   
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/
 
 
AS OF 400 AM EDT WEDNESDAY...THURSDAY NIGHT WILL REMAIN QUIET  
WITH SURFACE HIGH PRESSURE RIDGE STILL RIDGING INTO OUR FORECAST  
AREA. A WARM FRONT APPROACHES NORTH OF THE INTERNATIONAL BORDER  
AND WILL RESULT IN SOME INCREASING CLOUDS ACROSS OUR AREA  
DURING THE OVERNIGHT HOURS AND HEADED INTO FRIDAY MORNING. THEN  
ON FRIDAY MORE INCREASING CLOUDS AND CHANCE FOR SHOWERS  
ESPECIALLY HEADED INTO FRIDAY EVENING AS WARM FRONT MOVES ACROSS  
OUR NORTHERN ZONES, ESPECIALLY ALONG THE INTERNATIONAL BORDER.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
 
 
AS OF 410 AM EDT WEDNESDAY...NO BIG CHANGES FOR EXTENDED PORTION  
OF THE FORECAST. PRETTY ACTIVE WEATHER WITH BELOW NORMAL  
TEMPERATURES. OUR NEXT COLD FRONT AND UPPER TROUGH LOOKS TO  
SWING INTO THE REGION FRIDAY NIGHT THROUGH SATURDAY WITH PERHAPS  
A REPEAT PERFORMANCE FROM EARLIER IN THE WEEK...LAKE EFFECT AND  
GUSTY SOUTHWEST WINDS ON THE FRONT-END FRIDAY NIGHT, FOLLOWED  
BY SCATTERED RAIN SHOWERS SATURDAY AND PERHAPS SOME UPSLOPE ON  
THE BACK-END SATURDAY NIGHT POST-FRONTAL PASSAGE. HIGH  
PRESSURE RETURNS FOR SUNDAY NIGHT INTO MONDAY WITH LOWS BACK IN  
THE 20S AND 30S AND HIGHS IN THE 40S, FOLLOWED BY A CHANCE FOR  
SHOWERS MONDAY NIGHT INTO TUESDAY ASSOCIATED WITH A WEAK FRONTAL  
PASSAGE.  
 

 
   
AVIATION /12Z WEDNESDAY THROUGH SUNDAY/
 
 
THROUGH 12Z THURSDAY...VFR CONDITIONS AT ALL TAF SITES, EXCEPT  
MVFR CIGS AT SLK. THINKING CLOUDS WILL CONTINUE TO LOWER  
ACROSS OUR TAF SITES THIS MORNING WITH MAINLY VFR CONDITIONS.  
EXPECT AREAL COVERAGE OF PRECIP TO EXPAND BTWN 12-16Z THIS  
MORNING WITH POCKETS OF MVFR CIGS POSSIBLE AS A COLD FRONT  
SWINGS THRU THE REGION. A BRIEF PERIOD OF IFR CIGS/VIS IS LIKELY  
AT SLK BTWN 13-16Z THIS MORNING, AS SOME LAKE ENHANCED MOISTURE  
DEVELOPS ON SOUTHWEST FLOW AHEAD OF BOUNDARY. BREEZY TO GUSTY  
WINDS WILL DEVELOP FROM THE SOUTHWEST AT 15 TO 25 KNOTS, BEFORE  
SHIFTING TO THE NORTHWEST THIS AFTN. A GRADUAL CLEARING TREND  
WITH VFR CONDITIONS RETURNS BY 00Z WEDS, EXPECT SOME LINGERING  
MVFR CIGS POSSIBLE AT SLK/MPV. ALSO, AS COLDER AIR MOVES OVER  
THE RELATIVELY WARMER LAKE CHAMPLAIN WATERS, SOME LOCALIZED MVFR  
CIGS ARE LIKELY OVERNIGHT AT BTV TAF SITE.  
 
OUTLOOK...  
 
THURSDAY: VFR. WINDY WITH GUSTS TO 30 KT. NO SIG WX.  
THURSDAY NIGHT: VFR. NO SIG WX.  
FRIDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. NO SIG WX.  
FRIDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. CHANCE SHRA.  
SATURDAY: MAINLY MVFR, WITH AREAS VFR POSSIBLE. LIKELY SHRA.  
SATURDAY NIGHT: MVFR. CHANCE SHRA, CHANCE SHSN.  
SUNDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. SLIGHT CHANCE SHRA,  
SLIGHT CHANCE SHSN.  
 

 
   
MARINE
 
 
LAKE WIND ADVISORY IS IN EFFECT FOR THIS AFTN INTO TONIGHT FOR  
GUSTY WEST TO NORTHWEST WINDS OF 15 TO 25 KNOTS, INCREASING TO  
20 TO 30 KNOTS TONIGHT. WAVE WILL BUILD 2 TO 4 FEET WITH SOME  
HIGHER WAVES IN THE BOARD LAKE POSSIBLE.  
 

 
   
CLIMATE
 
 
BELOW ARE THE RECORD LOW MAX TEMPERATURES FOR OCTOBER 18, 2018:  
 
BURLINGTON, VT 38 (1976)  
MONTPELIER, VT 36 (1976)  
ST. JOHNSBURY, VT 38 (1939)  
PLATTSBURGH, NY 35 (1989)  
SARANAC LAKE, NY 33 (2015)  
MASSENA, NY 36 (1989)  
 

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

 
 

 
SYNOPSIS...TABER  
NEAR TERM...TABER  
SHORT TERM...NEILES  
LONG TERM...NEILES  
AVIATION...TABER  
MARINE...  
CLIMATE...LAHIFF  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab VT Page
The Nexlab NY Page Main Text Page