Area Forecast Discussion
Issued by NWS Burlington, VT

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000
FXUS61 KBTV 201802
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
202 PM EDT MON OCT 20 2014

.SYNOPSIS...
WEAK HIGH PRESSURE OVER THE AREA TODAY WILL BRING ABOUT THE ONLY
DRY DAY OF THE WEEK. BELOW NORMAL TEMPERATURES WILL BE THE RULE
TODAY AS PLENTY OF CLOUD COVER PERSISTS. A DEVELOPING LOW PRESSURE
SYSTEM TO OUR WEST WILL STRENGTHEN AND MOVE TOWARD LONG ISLAND
TUESDAY INTO WEDNESDAY. AS IT DOES...LIGHT RAIN IS EXPECTED OVER
THE AREA DURING THIS TIME PERIOD. THE LOW WILL REMAIN NEARLY
STATIONARY OVER LONG ISLAND DURING THE MIDDLE AND LATTER PART OF
THE WEEK AND SET THE STAGE FOR MORE STEADIER RAIN ACROSS NORTHERN
NEW YORK AND VERMONT.

&&

.NEAR TERM /UNTIL 7 AM TUESDAY MORNING/...
AS OF 150 PM EDT MONDAY...ONCE AGAIN, FORECAST FOR THE DAY IS
PRETTY MUCH ON TRACK. LIGHT RAIN HAS JUST REACHED THE ST LAWRENCE
VALLEY AND RADAR SHOWS ECHOS STREAMING EASTWARD. THINK THAT MUCH
OF THIS WILL DRY UP AS IT DOES MOVE EAST AS THE LOW LEVEL AS
FAIRLY DRY. STILL A FEW SPRINKLES/BRIEF LIGHT RAIN IS NOT OUT OF
THE QUESTION FOR THE FAR NORTHERN SECTIONS CLOSE TO THE
INTERNATIONAL BORDER. HAVE THUS MODIFIED THE POP FIELD TO REFLECT
THIS MORE EAST/NORTHEAST MOVEMENT.

HAVE MADE ADJUSTEMENTS TO THE POP FIELD EVOLUTION OVERNIGHT BASED
UPON THE LATEST 12Z GUIDANCE, WITH A LITTLE MORE WEIGHT TOWARD THE
SREF OUTPUT.

BASICALLY WITH THE UPPER TROF BEGINNING TO DEEPEN, THE DEEPEST
MOISTURE (AND ASSOCIATED PRECIPITATION) WON`T BE MAKING AS MUCH
OF A PROGRESSION TO THE EAST, BUT RATHER MORE TO THE SOUTH. THUS
HAVE KEPT HIGHEST POPS OUT ACROSS WESTERN SECTIONS OF NORTHERN NEW
YORK, TRENDING LOWER THE FARTHER SOUTH AND EAST ONE GOES. SO HAVE
A 60-80% OUT IN THE ST LAWRENCE VALLEY DOWN TO 15-25% IN THE LOWER
CONNECTICUT RIVER VALLEY. TEMPERATURES ALOFT ARE WARMING FAIRLY
QUICKLY (WHITEFACE MOUNTAIN SUMMIT HAS JUST REACHED 32F), SO NOT
EXPECTING ANYTHING OTHER THAN RAIN.

STILL NEED TO EVALUATE OVERNIGHT LOWS, BUT THINKING WITH THE
CLOUDS AND PRECIPITATION, IT WON`T DROP ALL THAT MUCH FROM
WHATEVER WE REACH FOR HIGHS THIS AFTERNOON.

&&

.SHORT TERM /7 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
AS OF 150 PM EDT MONDAY...UPPER TROF OFF TO THE WEST WILL
DEEPEN/INTENSIFY AND ULTIMATELY CUT-OFF DOWN OVER THE MID-ATLANTIC
TUESDAY NIGHT/WEDNESDAY MORNING. THE ASSOCIATED SURFACE LOW WILL
SET UP SHOP JUST SOUTH OF LONG ISLAND. AND AS WE KNOW, CUT-OFFS
ARE "CUT-OFF" FROM THE MAIN FLOW, SO THAT MEANS THEY DON`T MOVE
VERY QUICKLY.

12Z GUIDANCE STILL ALL SHOWING THIS SAME SCENARIO, SO CONFIDENCE
IS HIGH THAT WE`VE GOT AN EXTENDED PERIOD OF VERY WET CONDITIONS.
DEEP EASTERLY FLOW WILL BECOME ENTRENCHED AND BRING IN COPIOUS
AMOUNTS OF ATLANTIC MOISTURE -- RESULTING IN A GOOD DEAL OF RAIN
TUESDAY AND ESPECIALLY WEDNESDAY (AND BEYOND).

NEED TO LOOK MORE AT THE 12Z GUIDANCE FOR QPF AMOUNTS, THOUGH
FIRST SKIM THROUGH SEEMS TO INDICATE WHAT WE CURRENTLY HAVE SEEMS
TO BE IN THE BALLPARK -- WHICH IS A WIDESPREAD 1"+ BY WEDNESDAY
NIGHT WITH EVEN MORE FALLING THURSDAY.

I`LL BE BACK IN A BIT WITH MORE DETAILS ON TUESDAY & WEDNESDAY.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 310 AM EDT MONDAY...LITTLE OVERALL CHANGE FROM PREVIOUS
COUPLE FORECASTS WITH REGARDS TO WIDESPREAD RAINFALL EXPECTED WEDS
NIGHT THRU FRIDAY. MANY INGREDIENTS COMING TOGETHER FOR A MODERATE
TO HEAVY RAINFALL EVENT WITH TOTAL QPF FROM THIS MULTI DAY EVENT
BETWEEN 1 AND 3 INCHES. THIS RAINFALL WILL CAUSE SIGNIFICANT IN BANK
RISES ON LOCAL STREAMS AND RIVERS...WITH SOME MINOR LOW LYING AND
POOR DRAINAGE FLOODING POSSIBLE. STILL SOME UNCERTAINTY OF EXACT
PLACEMENT OF HEAVIEST QPF AND POTENTIAL IMPACTS FROM TERRAIN
ASSOCIATED WITH A MODERATE EASTERLY FLOW.

LATEST GUIDANCE IN GOOD AGREEMENT WITH CLOSED 5H/7H CIRCULATION
NEAR NORFOLK VA ON 00Z THURS...SLOWLY MOVING NORTH ALONG THE MID
ATLANTIC COASTLINE AND BECOMING A VERTICALLY STACKED SYSTEM
NEAR NYC BY 00Z FRIDAY. THE COMBINATION OF SFC HIGH PRES ACRS
CENTRAL/SOUTHERN CANADA AND DEVELOPING LOW PRES OVER NYC...WILL
PRODUCE A 3 TO 4 850MB U VECTOR WIND ANOMALY OVER THE NE
CONUS...WITH SPEED VALUES BETWEEN 35 AND 45 KNOTS. THIS DEEP AND
MODERATELY STRONG EASTERLY FLOW WILL ADVECT PLENTY OF WARM ATLANTIC
MOISTURE BACK INTO OUR AREA...WITH PW VALUES APPROACHING 1.0" BY
THURS OR 1 TO 2 STD ABOVE NORMAL. IN ADDITION...PROGGED 85H TEMPS
WARM BETWEEN 7-9C BY THURS. THE AVAILABLE MOISTURE...COMBINED WITH
THE SLOW MOVING SYSTEM WILL PRODUCE A PROLONG 2 TO 3 DAY RAINFALL
EVENT ACRS OUR AREA. IN ADDITION...GFS BUFKIT SOUNDINGS SHOW DEEP
850 TO 500MB EASTERLY FLOW...WHILE SFC TO 875MB FLOW IS FROM THE
NORTH/NORTHWEST AT BTV...RESULTING IN ENHANCED CONVERGENCE ACRS THE
CHAMPLAIN VALLEY...HELPING TO PRODUCE ADDITIONAL LIFT/QPF. IF POSITION OF LLVL
JET IS FURTHER NORTH...LIKE SOME MODELS PREDICT...ALONG WITH
BETTER RIBBONS OF DEEPER MOISTURE...QPF WOULD BE MUCH LESS ACRS OUR
AREA. WILL CONT WITH MODEL CONSENSUS OF A MODERATE TO HEAVY QPF...AND
FOLLOW HPC QPF GUIDANCE CLOSELY. THIS SUGGESTS A WIDESPREAD 1 TO
3 INCH EVENT...WITH LIGHTER AMOUNTS ACRS THE SLV/WESTERN
DACKS...AND NEK/PARTS OF THE LWR CT RIVER VALLEY FROM EASTERLY
DOWNSLOPE...AND SOME HIGHER VALUES IN THE FAVORABLE EASTERLY
UPSLOPE REGIONS OF THE CENTRAL VT MTNS AND EASTERN DACKS. THE
STEADIER/HEAVIER PRECIP SHOULD SLOWLY TAPER OFF ON SATURDAY...WITH
LIGHT MAINLY TERRAIN DRIVEN SHOWERS POSSIBLE. A DRIER PATTERN WITH
BUILDING HGHTS RETURNS FOR EARLY NEXT WEEK...WITH TEMPS CLIMBING
TO ABOVE NORMAL LEVELS.

GIVEN NORTHERLY SFC FLOW AND LOTS OF CLOUDS/PRECIP...EXPECT VERY
LITTLE DIURNAL CHANGE IN TEMPS FROM WEDS NIGHT THRU FRIDAY...WITH
HIGHS MAINLY IN THE 40S TO L50S AND LOWS RANGING FROM THE U30S TO
MID 40S. GIVEN MOIST ADIABATIC SOUNDING PROFILES...LITTLE CHANGE
IN TEMPS ARE EXPECTED BETWEEN THE VALLEYS AND MTNS DURING THIS TIME
PERIOD. UNFORTUNATELY GIVEN THE WARMING THERMAL PROFILES...THE
THREAT FOR ACCUMULATING SNOWFALL IS VERY LIMITED AND CONFINED TO
THE HIGHEST SUMMITS OF THE DACKS ABOVE 4500 FT...VERY EARLY ON
TUES. TEMPS WILL WARM TO NEAR NORMAL LVLS BY SAT/SUNDAY WITH
READINGS IN THE 40S/50S FOR HIGHS AND LOWS MAINLY IN THE 30S/40S.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
     AIRMET ADVSYS FOR MODERATE ICING POTL FROM 080 AGL TO 180 AGL
THROUGH 03Z AREA WIDE...

THROUGH 18Z TUESDAY...SLOWLY DETERIORATING CONDS OVER THE NEXT 24
HOURS AS UPPER LEVEL ENERGY SLOWLY DEVELOPS ACROSS THE NRN MID-
ATLANTIC INTO THE NORTHEAST. BEST COVERAGE OF SHOWERS/LIGHT RAIN
TO OCCUR AT NORTHERN NY TERMINALS OF KMSS/KSLK THIS EVENING INTO
THE OVERNIGHT HOURS AND BEYOND...WITH SOME ON AND OFF
SPRINKLES/VERY LIGHT SHOWERS ALSO POSSIBLE AT KBTV/KPBG AFTER 00Z
OR SO. MAINLY DRY AT KMPV/KRUT UNTIL AFTER 12Z TUE...AND POSSIBLY
BEYOND. CIGS A MAINLY VFR THROUGH 06Z...THOUGH SOME PATCHY MVFR AT
KSLK/KMSS IN EVENING SHOWER ACTIVITY. AFTER 06Z CONDS SLOWLY LOWER
TO MVFR AT MOST NRN NY TERMINALS AND POSSIBLY KBTV...REMAINING
VFR AT KMPV/KRUT. WINDS GENERALLY LIGHT AND VRB TO LIGHT
SOUTH/SOUTHWESTERLY THROUGH 00Z...TRENDING CALM TO LIGHT
EAST/NORTHEASTERLY AT ALL TERMINALS EXCEPT KRUT WHERE LIGHT
SOUTHEASTERLY FLOW WILL DEVELOP. AT KMSS NORTHEASTERLY FLOW TO
STRENGTHEN AFTER 09Z TO 10-15 KTS WITH ENHANCED GUSTINESS.

OUTLOOK 18Z TUESDAY THROUGH SATURDAY...

18Z TUESDAY THROUGH 12Z WEDNESDAY...A MIX OF VFR/MVFR/IFR AS UPPER
LOW AND ASSOCIATED SHOWERS/PERIODS OF LIGHT RAIN AFFECT THE REGION.

12Z WEDNESDAY THROUGH 12Z FRIDAY...WIDESPREAD AND/OR PERIODS OF
RAIN...OCCNLY HEAVY TO AFFECT PORTIONS OF THE REGION AS UPPER LOW
PRESSURE LIFTS SLOWLY ALONG THE NEW ENGLAND COAST. PREVAILING
MVFR/IFR THE GENERAL RULE.

12Z FRIDAY ONWARD...SLOWLY IMPROVING CONDS AS UPPER LOW PULLS AWAY
TO THE NORTHEAST AND COVERAGE OF RAIN/SHOWERS LESSENS OVER TIME.
SOME LINGERING IFR/MVFR STILL LIKELY EARLY IN THE
PERIOD...TRENDING TO MAINLY VFR AFTER 12Z SATURDAY.

&&

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

&&

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





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