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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