Area Forecast Discussion
Issued by NWS Burlington, VT

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000
FXUS61 KBTV 041439
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
1039 AM EDT SAT JUL 4 2015

.SYNOPSIS...
A FEW SHOWERS ARE POSSIBLE ACROSS SOUTHERN VERMONT THIS
MORNING...FOLLOWED BY ADDITIONAL SHOWERS OVER NORTHERN NEW YORK
INTO NORTHERN VERMONT THIS AFTERNOON INTO THE EVENING HOURS.
OVERALL...PRECIPITATION AMOUNTS WILL BE LIGHT AND SCATTERED IN
NATURE. TEMPERATURES WILL HOLD IN THE 70S TODAY WITH MORE
CLOUDS...BUT WILL BE WARMER ON SUNDAY WITH EXPECTED SUNSHINE.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1039 AM EDT SATURDAY...CURRENT RADAR TRENDS SHOWING LIGHT
RAIN SHOWERS MOVING NORTHEAST FROM NEW YORK STATE ACROSS THE
SOUTHERN PORTION OF VERMONT AT THIS TIME. THE BEST CHANCE FOR
SHOWERS THIS MORNING WILL BE FROM RUTLAND AND WINDSOR COUNTIES
SOUTHWARD. BASED ON LATEST RADAR TRENDS HAVE LOWERED POPS FOR THIS
MORNING ACROSS NORTHERN NEW YORK AND THE NORTHERN HALF OF
VERMONT...AND HAVE GONE WITH A DRY FORECAST FOR THE REMAINDER OF
THIS MORNING THROUGH EARLY THIS AFTERNOON. OTHERWISE...NO CHANGES
TO THE REMAINDER OF THE FORECAST AT THIS TIME.

PREVIOUS DISCUSSION FROM 706 AM EDT SATURDAY...UPDATED FCST TO
INCREASE POPS ACROSS CENTRAL AND SOUTHERN VT ZONES TO 70 TO 80%
BASED ON LATEST RADAR AND HRRR DATA. RADAR SHOWS A RATHER LARGE
AREA OF LIGHT RAIN WITH EMBEDDED AREAS OF MODERATE RAIN MOVING
TOWARD RUTLAND AND WINDSOR COUNTIES THIS MORNING. THIS RAIN WILL
WEAKEN SOME AS IT ENCOUNTERS A VERY DRY AIRMASS OVER OUR CWA...BUT
GIVEN FLOW ALOFT...JET ORIENTATION AND MAGITUDE OF 5H
VORT...THINKING MEASURABLE PRECIP IS VERY LIKELY ACROSS RUTLAND
AND WINDSOR COUNTIES THIS MORNING. OTHERWISE...THIS RAIN WILL
SHIFT EAST OF OUR CWA BY EARLY THIS AFTERNOON. ANOTHER INTERESTING
AREA TO WATCH IS SLV/WESTERN DACKS...AS LATEST RADAR TRENDS SHOW
ADDITIONAL SHOWERS DEVELOPING WITH EVEN A LIGHTNING STRIKE
OCCURRING IN THE PAST COUPLE OF MINUTES. HAVE MENTION CHC POPS BUT
WILL KEEP MENTION OF THUNDER OUT OF FCST ATTM...DUE TO THE LACK OF
INSTABILITY OVER OUR CWA. OTHER ADJUSTMENT IS TO LOWER TEMPS
SEVERAL DEGREES DUE TO MORE CLOUDS.

FCST CHALLENGE THROUGH THIS EVENING WILL BE CHANCES FOR PRECIP
AND AREAL COVERAGE OF ANY SHOWERS. 00Z ALBANY SOUNDING SHOWS A
DEEP DRY LAYER FROM 850 TO 300MB WITH PW VALUE OF ONLY 0.49".
HOWEVER...DEEPER MOISTURE CONTS TO STREAM QUICKLY FROM SW TO NE
ACROSS THE MID ATLANTIC STATES INTO THE NE CONUS...AHEAD OF S/W
TROF OVER THE GREAT LAKES AND STRONG 25H JET. IN ADDITION...TO
MOISTURE STREAMING INTO OUR CWA...WATER VAPOR SHOWS EMBEDDED 5H
VORT IN THE FAST PROGRESSIVELY FLW ALOFT OVER CENTRAL OHIO. USING
THE RADAR AND COMPOSITE REFLECTIVITY PROGS OFF THE HRRR THINKING
INITIAL SURGE OF MOISTURE NOW LOCATED OVER CENTRAL PA INTO NY WILL
ADVECT NE INTO OUR CENTRAL/SOUTHERN CWA...WHILE WEAKENING DUE TO
DRY AIR ALOFT. BEST CHANCE FOR MEASURABLE QPF WILL BE SOUTH OF A
SLK TO BTV TO MPV LINE THIS MORNING...WITH PRECIP AMOUNTS
GENERALLY < 0.10 ACROSS RUTLAND/WINDSOR COUNTIES. WILL INCREASE
POPS AND MENTION LIKELY (60%) ACROSS OUR SOUTHERN TWO COUNTIES AND
TAPER TO NIL NEAR THE INTERNATIONAL BORDER. MEANWHILE...THIS
AFTERNOON ADDITIONAL S/W ENERGY LOCATED OVER THE NORTHERN GREAT
LAKES WILL APPROACH THE SAINT LAWRENCE VALLEY. GFS/NAM AND LOCAL
MODELS SHOW ADDITIONAL RAIN SHOWERS WITH EMBEDDED RUMBLES OF
THUNDER DEVELOPING OVER THE SLV/WESTERN DACKS AFTER 18Z.
INTERESTING THE LOCAL MODELS SHOW A WEAK LAKE BREEZE
BOUNDARY...ALONG WITH A DIFFERENTIAL HEATING BOUNDARY DEVELOPING
ON EDGE OF CLOUD DECK...WITH SFC BASED CAPE VALUES BTWN 500 AND
800 J/KG. THINKING SCATTERED SHOWERS WILL DEVELOP OVER THE
SLV/WESTERN DACKS BTWN 18Z- 21Z...AND MOVE EASTWARD TWD THE CPV
VALLEY AROUND 00Z...AND THRU CENTRAL/NORTHERN NY BY 03Z. HAVE
MENTIONED HIGH CHC TO LOW LIKELY POPS TO COVER THIS SCENARIO LATER
TODAY...WITH QPF GENERALLY BTWN A TRACE TO 0.25" IN THE HEAVIER
SHOWERS. TEMPS WILL BE TRICKY WITH A VARIETY OF CLOUDS LEVELS
EXPECTED...WHICH WILL HOLD VALUES MAINLY IN THE 70S. A FEW HIGHER
VALUES ARE POSSIBLE IN THE SLV WHERE MORE SUN IS EXPECTED THIS
MORNING INTO EARLY AFTN HOURS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
AS OF 400 AM EDT SATURDAY...NORTHERN STREAM 5H VORT WILL SWING
ACROSS OUR CWA THIS EVENING...WHILE RIBBON OF ENHANCED 850 TO
500MB MOISTURE QUICKLY SHIFTS INTO NORTHERN MAINE BY 06Z. ANY
SHOWERS WILL WEAKEN OR BE EAST OF OUR CWA BY MIDNIGHT TONIGHT.
WILL CONTINUE TO CARRY CHC POPS DURING THE EVENING HOURS...WITH
THE MAIN FOCUS FOR SCATTERED SHOWERS ACROSS THE EASTERN DACKS INTO
CENTRAL/NORTHERN VT...INCLUDING THE CHAMPLAIN VALLEY. GIVEN TIMING
OF SHOWERS...SOME EVENING ACTIVITIES ASSOCIATED WITH THE HOLIDAY
MAYBE IMPACTED...ESPECIALLY ACROSS THE NORTHERN CPV VALLEY INTO
PARTS OF NORTHERN VT BTWN 00Z AND 03Z. EXPECT AREAS OF CLEARING TO
DEVELOP AFT 06Z WITH 1021MB SFC HIGH PRES BUILDING INTO OUR CWA.
SOME PATCHY FOG/BR IS POSSIBLE TOWARD SUNRISE...ESPECIALLY OVER
THE DEEPER/PROTECTED RIVER VALLEYS OF THE DACKS. LOW TEMPS WILL BE
HIGHLY DEPEND UPON CLEARING...MAINLY 40S MTNS VALLEYS TO MID/UPPER
50S CPV.

SUNDAY AND MONDAY...MID/UPPER LVL RIDGE DEVELOPS ACROSS THE NE CONUS
WITH WEAK SFC HIGH PRES. STILL NOTICING ANOTHER 5H VORT IN THE NW
FLOW ALOFT IMPACTING NORTHERN VT BTWN 18Z-00Z SUNDAY...WHICH MAY
PRODUCE A FEW SPRINKLES. MOISTURE IS VERY LIMITED. PROGGED 85H TEMPS
NEAR 12C....SUPPORT LOWER 70S MTNS/NEK TO NEAR 80F WARMER VALLEYS ON
SUNDAY. MONDAY WILL FEATURE MOSTLY SUNNY SKIES AND MILD TEMPS.
PROGGED 85H TEMPS WARM BTWN 12C AND 14C...SUPPORTING MID/UPPER 70S
MTN TOWNS TO LOWER 80S VALLEYS.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 400 AM EDT SATURDAY... A HINT OF SUMMER NEXT WEEK AS
HEIGHTS AND TEMPERATURES RISE TO OR JUST ABOVE NORMAL WITH A SURGE
OF MOISTURE AND SOME THUNDERSTORMS ON TUE. THEREAFTER...STILL LOTS
OF QUESTIONS/DIFFERENCES ON TIMING/PROGRESSION OF FRONT THAT
DELIVERS OUR SHRA/TSRA LATE TUE/WED.

REST OF DISCUSSION TAKEN FROM DAYSHIFT AS SAME ISSUES/QUESTIONS OF
PAST FEW DAYS.

SHORT WAVE RIDGING ON MONDAY BRINGING TEMPS IN THE 80S WITH 850
TEMPS RISING TO 14-15C WILL BE PUSHING EAST MONDAY NIGHT AND TUE.

MODELS SIMILARLY INCREASING HUMIDITY AND INSTABILITY (1000-2000J/KG
CAPE) ON TUESDAY AHEAD OF A FRONTAL SYSTEM AS SOUTHWEST FLOW ADVECTS
MOISTURE INTO THE REGION. SO THAT WILL INCREASE OUR CHANCES OF
SHOWERS AND THUNDERSTORMS THROUGH THROUGH TUESDAY NIGHT. LITTLE
CHANGE IN 850 TEMPS SO TEMPS AGAIN IN THE MID 80S.

WHERE MODELS DIFFER IS ON HOW FAST THE FRONTAL SYSTEM MOVES THROUGH
WITH GFS BRINGING FRONT THROUGH BY WEDNESDAY MORNING WHILE ECMWF IS
SLOWER AND BRINGS IT THROUGH LATER IN THE DAY. BOTH MODELS SHOW
UPPER TROF WEAKENING AND LIFTING NORTH, SO NOT EXPECTING A DEEPENING
TROF LIKE WE`VE HAD LATELY. THE TIMING OF THE FRONT WOULD MAKE A
SIGNIFICANT DIFFERENCE IN THE CONVECTIVE PROBABILITIES, SO WENT WITH
A BLEND WITH SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS HANGING
AROUND ON WED. TEMPS A BIT COOLER ON WED.

SOME UNCERTAINTY CONTINUES THU-FRI AS FLOW ALOFT IS GENERALLY
WESTERLY WITH WEAK TROFFING SO CAN`T COMPLETELY RULE OUT A SHOWER
WITH TEMPERATURES NEAR NORMAL FOR THIS TIME OF YEAR (80/60).

&&

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
THROUGH 12Z SUNDAY...CLOUDS INCREASING AND THICKENING WITH SOME
SCT SHOWERS DURING THE DAY BUT DRY AT NIGHT. VFR EXPECTED THROUGH
THE PERIOD WITH LIGHT SOUTHERLY WINDS.

OUTLOOK 00Z SUNDAY THROUGH WEDNESDAY...

SUN...MAINLY VFR.
MON...MAINLY VFR UNDER HIGH PRESSURE. LCL LIFR FG PSBL KMPV/KSLK.
TUE..MAINLY VFR. SCT MVFR TSRA WITH FRONTAL PASSAGE TUE NIGHT.
WED...MAINLY VFR. SCT MVFR POST FRONTAL -SHRA.

&&

.EQUIPMENT...
KTYX RADAR WILL BE OUT OF SERVICE UNTIL TUESDAY OR LATER.

&&

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

&&

$$
SYNOPSIS...TABER
NEAR TERM...WGH/TABER
SHORT TERM...TABER
LONG TERM...SLW
AVIATION...SLW
EQUIPMENT...WFO BTV



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