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Area Forecast Discussion
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000
FXUS61 KBTV 241941
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
341 PM EDT THU JUL 24 2014

.SYNOPSIS...
DRY WEATHER IS EXPECTED RIGHT THROUGH SATURDAY AS HIGH PRESSURE
BUILDS DOWN FROM CANADA. HIGH TEMPERATURES WILL BE JUST BELOW
SEASONAL NORMALS ON FRIDAY AND THEN RIGHT AROUND SEASONAL NORMAL
SATURDAY. A CHANCE WILL TAKE PLACE SATURDAY NIGHT INTO SUNDAY AS
AN UPPER LEVEL TROUGH OF LOW PRESSURE MOVES INTO THE REGION AND
ENHANCES THE POTENTIAL FOR SHOWERS AND A FEW THUNDERSTORMS.

&&

.NEAR TERM /UNTIL 8 AM FRIDAY MORNING/...
AS OF 339 PM EDT THURSDAY...DIURNALLY DRIVEN CUMULUS OVER THE
MOUNTAINS WILL CONTINUE TO DECREASE THIS AFTERNOON AND SHOULD
MAINLY BE GONE BY SUNSET. DRIER AIR IS ALSO MOVING INTO THE REGION
ON NORTHWEST FLOW ALOFT...WHICH SHOULD ALLOW FOR BELOW NORMAL
TEMPERATURES TONIGHT WITH LOWS IN THE MID 40S TO MID 50S. BULK OF
THE SMOKE THAT HAS GOTTEN PICKED UP IN THE NORTHWEST FLOW ALOFT
SHOULD PASS TO OUR SOUTHWEST...BUT STILL SOME OVER QUEBEC THAT
COULD MAKE IT INTO THE REGION.

&&

.SHORT TERM /8 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
AS OF 339 PM EDT THURSDAY...THE COMBINATION OF A RELATIVELY DRY
AIR MASS AND LIMITED FORCING SUGGESTS ANOTHER DRY DAY IS IN STORE
FOR THE AREA ON FRIDAY. THERE SHOULD BE SHALLOW CUMULUS FORMING
OVER THE MOUNTAINS ONCE AGAIN...BUT VERTICAL DEPTH SHOULD BE
LIMITED AND NOT BE ABLE TO PRODUCE ANY PRECIPITATION. WE SHOULD
SEE WARMER TEMPERATURES THAN THURSDAY...BUT HIGHS WILL BE A DEGREE
OR TWO BELOW SEASONAL NORMALS. DRY WEATHER CONTINUES FRIDAY NIGHT
INTO SATURDAY WITH HIGHS GETTING TO SEASONAL NORMALS ON SATURDAY.
CLOUDS WILL BE ON THE INCREASE THROUGHOUT THE DAY AND ESPECIALLY
SATURDAY NIGHT AS AN UPPER LEVEL TROUGH OF LOW PRESSURE BEGINS TO
DEVELOP UPSTREAM AND EVENTUALLY MOVES INTO THE REGION LATE
SATURDAY NIGHT AND ESPECIALLY SUNDAY. ENOUGH FORCING SHOULD
DEVELOP SATURDAY NIGHT FOR A CHANCE OF SHOWERS...WHICH GOING
FORECAST ALREADY HAS...AND WILL CONTINUE THIS IDEA.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 315 PM EDT THURSDAY...PRIMARY WEATHER NEWS FOR THE EXTENDED
PERIOD IS THE ANTICIPATED DEVELOPMENT OF A LONG-WAVE TROUGH ACROSS
THE EASTERN THIRD OF THE COUNTRY THAT WILL RESULT IN A GENERALLY
UNSETTLED AND SLIGHTLY COOLER THAN NORMAL FIRST FEW DAYS OF THE
WEEK.

PRIMARY 12Z GUIDANCE (GFS & ECMWF) STILL IN LINE WITH EACH OTHER
AND WITH THEIR RESPECTIVE PRIOR RUNS WITH LARGE SCALE PICTURE WITH
THE LONG-WAVE TROUGH. STILL OFFER SLIGHTLY DIFFERENT TIMING WITH
RESPECT TO INDIVIDUAL SHORTWAVES THAT WILL BE ZIPPING THROUGH THE
FLOW, AND IT'S REALLY THOSE SHORTWAVES THAT WILL DRIVE THE WEATHER
WE SEE. BECAUSE OF THE OVERALL SIMILARITY BETWEEN MODELS, I
POPULATED THE GRIDDED FORECAST DATASET WITH A BLEND OF THEM ALL.

HERE ARE THE DAILY SPECIFICS:

SUNDAY...TIMING IS STILL UNCERTAIN, BUT THE MORNING HOURS WE MAY
BE DEALING WITH A BATCH OF SHOWERS AND PERHAPS AN EMBEDDED
T-STORM THANKS TO A SHORTWAVE PASSING ACROSS THE REGION. WITH SOME
BREAKS OF SUN IN THE AFTERNOON THAT COULD BUBBLE UP SOME SCATTERED
SHOWERS OR T-STORMS. SURFACE BASED INSTABILITY GUIDANCE FROM THE
GFS SHOWS SOME MODERATE INSTABILITY, BUT THAT BEGINS TO WANE BY
LATE AFTERNOON. PART OF THIS INSTABILITY MAY BE DRIVEN IN THE
MODELS BY THE RATHER HIGH SURFACE DEW POINTS (MID-UPPER 60S). BEST
MID LEVEL WINDS AND SHEAR VALUES ARE SOUTH AND EAST OF THE AREA,
SO ANY CONVECTION WE DO SEE SHOULD NOT BE ALL THAT ORGANIZED OR
STRONG. THAT SAID, BECAUSE OF THE UNCERTAIN TIMING OF THE
SHORTWAVE, IF THE SHORTWAVE COMES THROUGH A LITTLE SLOWER, THEN
SUNDAY AFTERNOON COULD BE MORE ACTIVE CONVECTIVELY. IN THE END, I
JUST PAINTED IN LIKELY LEVEL POPS FOR THE ENTIRE DAY. NO REASON TO
TRY TO GET MORE CUTE THAN IS NECESSARY AT THIS POINT. 850MB
TEMPERATURES AROUND 13-14C, WHICH UNDER FULL SUNSHINE WOULD
SUPPORT LOW/MID 80S FOR HIGHS. HOWEVER, CLOUDS SHOULD HOLD TEMPERATURES
BACK TO ABOUT 80F, THOUGH THAT WILL BE HIGHLY DEPENDENT ON WHAT WE
SEE FOR SUN. COULD BE HIGHER. COULD BE LOWER.

SUNDAY NIGHT/MONDAY...NEXT SHORTWAVE ROUNDING THE BASE OF THE
UPPER TROUGH COMES INTO THE REGION. TIMING DIFFERENCES BETWEEN THE
MODELS, SO AGAIN WON'T TRY TO SLICE THE BALONEY TOO THIN. SO
SOMETIME IN THIS PERIOD WE'LL SEE ANOTHER BATCH OF SHOWERS WITH
EMBEDDED T-STORMS ROLL THROUGH. INSTABILITY PARAMETERS IN THE
MODELS ARE NOT IMPRESSIVE AT ALL, SO I JUST CALLED IT "SLIGHT
CHANCE" FOR T-STORMS. AGAIN, A BUNCH OF CLOUDS AND WITH THE
MID/UPPER LEVEL TEMPERATURES FALLING DUE TO THE SLOWLY APPROACHING
LONGWAVE TROUGH (850MB TEMPERATURES SHOULD BE 10-12C), MONDAY IS
LOOKING A LITTLE COOLER THAN SUNDAY - HIGHS IN THE MID 70S, ABOUT
5-7F BELOW NORMAL.

TUESDAY/WEDNESDAY...LONGWAVE TROUGH AXIS WILL BE JUST OFF TO OUR
WEST, OVER THE EASTERN GREAT LAKES. AT THIS POINT THE MODELS
AREN'T SHOWING ANY SIGNIFICANT SHORTWAVES MOVING THROUGH THE FLOW,
SO THE PRIMARY TRIGGER MECHANISM FOR ANY CONVECTION WILL BE
DAYTIME HEATING. SO HAVE PAINTED IN CHANCE LEVEL POPS DURING THE
DAY AND MINIMAL POPS FOR TUESDAY & WEDNESDAY NIGHTS. 850MB
TEMPERATURES CONTINUE TO FALL, AND WILL BE DOWN AROUND 10C. THIS
WILL SUPPORT TEMPERATURES IN THE MID 70S AS ADDITIONAL SUN WILL
OFFSET THINGS A BIT. 

THURSDAY...LONGWAVE TROUGH PATTERN LOOKS TO "RELOAD" ACROSS THE
CENTRAL PLAINS, SO WEAK RIDGING DEVELOPS OVER US. SHOULD BE THE
DRIEST OF THE EXTENDED FORECAST PERIOD, THOUGH ANTICIPATE DAYTIME
HEATING TO AGAIN RESULT IN A FEW SHOWERS ESPECIALLY ACROSS THE
HIGHER TERRAIN. 850MB TEMPERATURES RISE BACK UP TO 12-13C, SO
HIGHS WILL BE CLIMBING CLOSER TO NORMAL WITH UPPER 70S TO PERHAPS
LOW 80S.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
THROUGH 18Z FRIDAY...CURRENTLY VFR, WITH DAYTIME CUMULUS FOCUSED
MORE ACROSS THE HIGHER TERRAIN. LOOKS LIKE A LAKE BREEZE IS
FORMING ALONG LAKE CHAMPLAIN AS WELL. WHAT YOU SEE IS WHAT YOU GET
FOR THE REST OF THE AFTERNOON. CLOUDS WILL MELT AWAY JUST PRIOR TO
SUNSET AND WINDS WILL BE NEAR CALM IN MOST AREAS.

PRIMARY FORECAST CHALLENGE CONCERNS POTENTIAL FOR PATCHY FOG LATE
TONIGHT. THERE ARE INDICATIONS IN THE GUIDANCE THAT THE DRIER AIR
COMING INTO THE AREA TODAY WILL LIMIT THE POTENTIAL FOR FOG. SOME
OTHER INDICATIONS THAT THERE WILL BE 5-10KTS OF WIND A FEW HUNDRED
FEET ABOVE GROUND THAT WOULD LEAN TOWARD MORE OF A STRATUS
SITUATION THAN FOG. IN ANY REGARD, ONLY SLK AND MPV ARE AT RISK
FOR ANY FOG/STRATUS. THINK FOG WILL REDUCE VISIBILITIES PRIMARILY
TO MVFR LEVELS, THOUGH WITH A LITTLE MORE MOISTURE AROUND MPV DUE
TO RECENT RAIN, THINK IFR CEILING WILL FORM LATE TONIGHT FOR JUST
A FEW HOURS.

BY 12Z FRIDAY, WE ARE BACK TO VFR AREA WIDE. 

OUTLOOK 18Z FRIDAY THROUGH TUESDAY...

18Z FRI - 00Z SUN...VFR. PERHAPS A TOUCH OF OVERNIGHT FOG AT MPV
AND/OR SLK.

00Z SUN ONWARD...TRENDING INCREASINGLY UNSETTLED. THOUGH MOSTLY
VFR...PERIODIC SHOWERS/STORMS WITH POSSIBLE BRIEF MVFR/IFR
VISIBILITY RESTRICTIONS.

&&

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

&&

$$
SYNOPSIS...EVENSON
NEAR TERM...EVENSON
SHORT TERM...EVENSON
LONG TERM...NASH
AVIATION...NASH





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