Area Forecast Discussion
Issued by NWS Albany, NY

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000
FXUS61 KALY 031049
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
649 AM EDT MON AUG 3 2015

.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE EASTERN GREAT LAKES
REGION TODAY.  THERE IS A CHANCE OF STRONG TO SEVERE THUNDERSTORMS
AHEAD OF THE COLD FRONT THIS AFTERNOON INTO TONIGHT.  THE COLD FRONT
WILL BE EAST OF THE REGION TUESDAY MORNING...BUT AN UPPER LEVEL
DISTURBANCE WILL CONTINUE THE THREAT FOR SCATTERED SHOWERS AND
THUNDERSTORMS TUESDAY AFTERNOON...AS COOLER AND DRIER AIR WILL
ARRIVE FOR WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
...SOME SEVERE THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON INTO
TONIGHT...

AS OF 648 AM EDT...AN H500 CLOSED UPPER LEVEL LOW CONTINUES TO BE
NEAR NRN ONTARIO AND JAMES BAY THIS MORNING. SEVERAL SHORT-WAVES
ROTATING AROUND THE UPPER LEVEL LOW WILL CONTINUE TO IMPACT THE
FCST AREA THE NEXT FEW DAYS. ONE SHORT-WAVE MOVING THROUGH THE
BASE OF THE LONG-WAVE TROUGH WILL IMPACT THE REGION LATER
TODAY...AS IT MOVES THROUGH THE LOWER GREAT LAKES REGION AND OHIO
VALLEY.

AT THE SFC...A WEAK SFC CYCLONE OVER THE CNTRL/ERN GREAT LAKES
REGION IS MOVING TOWARDS SE ONTARIO THIS MORNING. THE FCST AREA
WILL BE IN A WARM SECTOR TODAY WITH SFC DEWPTS RISING INTO THE
U50S TO PERHAPS M60S. A PREFRONTAL SFC TROUGH AHEAD OF THE MAIN
COLD FRONT WILL MOVE ACROSS WRN-CNTRL NY LATE THIS MORNING INTO
THE AFTERNOON. CONVECTION IS EXPECTED TO FIRE JUST AHEAD OR IN THE
PREFRONTAL SFC TROUGH ZONE BTWN THE SFC TROUGH AND THE COLD FRONT.

THE GUIDANCE CONTINUES TO INDICATE A THREAT WILL INCREASE FOR
SOME STRONG TO SEVERE THUNDERSTORMS THIS AFTERNOON INTO TONIGHT.
SOME SCT STRONG TO SEVERE THUNDERSTORMS MAY REACH THE SRN
DACKS/W-CNTRL MOHAWK VALLEY BTWN 2-5 PM...THEN MUCH OF ERN NY BTWN
5-8 PM INCLUDING THE CAPITAL REGION...AND THEN POTENTIALLY
SPREADING INTO WRN NEW ENGLAND BTWN 8-11 PM. THE LATEST HIRESWRF
REF PRODUCT CONTINUES THIS TREND...THOUGH THE HRRR IS A LITTLE
FASTER. THE 4-KM WPC SPC WRF ACTUALLY HAS SOME CONVECTION FIRE
WITH AN OUTFLOW BOUNDARY NEAR THE LAKE GEORGE REGION AROUND 2-4
PM. WE ARE GOING TO STICK CLOSER TO THE HIRESWRF FOR THE TIMING AT
THIS POINT.

THE BEST MID LEVEL LAPSE RATES WILL BE OVER THE FCST AREA IN THE
EARLY TO MID PM BASED ON THE GFS/NAM. THESE LAPSE RATES WILL BE IN
THE 6.5-7+C/KM RANGE. THERE ARE SIGNIFICANT DIFFERENCES IN THE
INSTABILITY PROFILES BTWN THE NAM/GFS. THE NAM IS ON THE HIGHER
END WITH SBCAPES OF ROUGHLY 1000-2000 J/KG WITH SLIGHTLY HIGHER
SFC DEWPTS. THE GFS HAS ONLY SBCAPES OF 500-1000 J/KG WITH
SLIGHTLY HIGHER POCKETS. THE SFC DEWPTS ARE LOWER ON THE GFS. THE
SFC TO BOUNDARY LAYER WINDS ARE FROM THE S/SW DURING THE DAY. THE
0-6 KM BULK VERTICAL WIND SHEAR VALUES INCREASE TO 35-45 KTS
DURING THE PM. SOME DEEP ORGANIZED CONVECTION IS ANTICIPATED WITH
LARGE HAIL AND DAMAGING WINDS POSSIBLE. MULTICELLS OR MULTICELL
LINES LOOK POSSIBLE ESPECIALLY WITH THE UNIDIRECTIONAL WIND
PROFILES IN THE BUFKIT SOUNDS. SOME BOWING ELEMENTS/WET MICROBURSTS
MAY OCCUR...AS INVERTED-V PROFILES ARE ALSO EVIDENT IN THE
SOUNDINGS. DAMAGING WINDS LOOK LIKE THE PRIMARY THREAT WITH SOME
POTENTIAL FOR LARGE HAIL AS THE SECONDARY THREAT.  ACTUALLY H850
TEMPS INCREASE TO +15C TO +19C OVER THE FCST AREA. HIGHS ARE
EXPECTED TO REACH THE M80S TO LOWER 90S IN THE VALLEY AREAS...AND
M70S TO L80S OVER THE HIGHER TERRAIN.

THE BETTER UPPER JET DYNAMICS ARRIVE TOWARDS NIGHTFALL...BUT
DECENT UPPER LEVEL DIVERGENCE OCCURS OVER ERN NY PRIOR TO THEN.
PWATS DO INCREASE TO 1.25-1.50+ INCHES OVER MOST OF THE
REGION...SO SOME LOCALLY HEAVY DOWNPOURS ARE POSSIBLE. WE WILL
CONTINUE THE TREND FROM THE PREVIOUS FORECAST IN THE ZONES/GRIDS
TO PHRASE THAT SOME STORMS MAYBE SEVERE IN THE MID PM TO LATE PM.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
TONIGHT...THE DEGREE OF HOW WIDESPREAD THE SEVERE WEATHER MAY
POTENTIALLY BE WILL DEPEND ON HOW FAST THE UPPER IMPULSE AND COLD
FRONT MOVE ACROSS THE REGION...SINCE THE INSTABILITY MAY POSSIBLY
BE WANING. AS MENTIONED ABOVE...THE BETTER UPPER LEVEL DYNAMICS
ARRIVE TOWARDS SUNSET...AN IMPRESSIVE CYCLONICALLY CURVED JET
STREAK AT H250 OF 85-95 KTS WILL PASS WEST OF THE HUDSON RIVER
VALLEY. ERN NY AND WRN NEW ENGLAND WILL BE NEAR THE RIGHT ENTRANCE
REGION OF THE JET STREAK. SOME ENHANCEMENT TO THE CONVECTION MAY
OCCUR...AND SOME OF THE MULTICELLS MAY GET INTO WRN ENGLAND. THERE
MAYBE AN ISOLATED SUPERCELL OR TWO CLOSER TO THE BETTER DEEP
SHEAR...WHICH LOOKS LIKE IT WOULD BE NORTH OF THE I-90 CORRIDOR AT
THIS POINT. HIGH CHC AND LIKELY POPS WERE MAINTAINED AHEAD OF THE
COLD FRONT...AS IT SAGS E/SE ACROSS THE FCST AREA. SOME HEAVY
DOWNPOURS WILL BE POSSIBLE...BUT THE PWATS DO NOT LOOK HIGHLY
ANOMALOUS AT THIS POINT /AROUND A STD DEV ABOVE NORMAL/. THE
THUNDERSTORMS SHOULD START AROUND MIDNIGHT OR SHORTLY THEREAFTER.
AT THIS POINT IT IS HARD TO TELL IF A WIDESPREAD OR MAJOR EVENT
WILL OCCUR FOR THE REGION....BUT WE AGREE WITH SPC AND HAVE AT
LEAST MODERATE CONFIDENCE FOR SOME SEVERE IN THE FCST AREA. LOWS
MON NIGHT WILL BE ON THE MILD SIDE WITH MID AND U60S FROM THE
EASTERN MOHAWK VALLEY...SOUTHERN REACHES OF THE LAKE GEORGE REGION
SOUTH AND EAST...AND U50S AND L60S NORTH AND WEST.

TUESDAY...THE COLD FRONT WILL BE NEAR WRN NEW ENGLAND BY
DAYBREAK. THE SFC DEWPT BOUNDARY WILL STILL BE PROGRESSING EAST
ACROSS ERN NY. THE NAM IS ADVERTISING ALOT OF INSTABILITY FOR TUE
WITH A DEEPLY SHEARED ENVIRONMENT. THE GFS HAS LESS AGAIN...BUT
THERE IS A SMALL AREA OF HIGH INSTABILITY FROM THE THE MASS PIKE
SOUTH AND EAST INTO NW CT. SPC DOES HAVE LITCHFIELD CTY CLIPPED BY
THE MARGINAL RISK. MID LEVEL LAPSE RATES WILL BE AROUND 6.5C/KM
WITH ANOTHER SHORT-WAVE ROTATING AROUND THE UPPER LEVEL LOW. WILL
HAVE TO MONITOR FOR SOME STRONG STORMS WITH GUSTY WINDS AND SMALL
HAIL /NO ENHANCED WORDING YET/...ESPECIALLY FROM THE CAPITAL
DISTRICT SOUTH AND EAST. LOW-LEVEL COLD ADVECTION WILL BE ONGOING
DURING THE LATE MORNING INTO THE PM. DOWNSLOPING EFFECTS OFF THE
ERN CATSKILLS/ERN DACKS MAY ALLOW MAX TEMPS TO GET INTO THE MID
AND U80S IN THE HUDSON RIVER VALLEY/CAPITAL REGION. EXPECT M70S TO
L80S IN MOST OTHER LOCATIONS...EXCEPT OVER THE SRN DACKS/SRN
GREENS WHERE SOME U60S TO L70S ARE POSSIBLE IN THE COLD ADVECTION
REGIME...AS H850 TEMPS LOWER TO +10C TO +16C FROM NW TO SE OVER
THE FCST AREA BY THE LATE PM. A SLIGHT TO LOW CHC OF THUNDERSTORMS
WILL CONTINUE UNTIL SUNSET.

TUESDAY NIGHT...WITH THE LOSS OF THE DIURNAL HEATING THE SCT
SHOWERS AND THUNDERSTORMS WILL DIMINISH QUICKLY. THE ISOLD-SCT
SHOWERS MAY LINGER THE LONGEST OVER THE SRN DACKS. LOWS WILL
GENERALLY BE IN THE MID 50S TO AROUND 60F WITH SOME U40S TO L50S
OVER THE SRN DACKS/SRN GREENS. HUMIDITY LEVELS WILL BE QUITE
COMFORTABLE.

WED-WED NIGHT...THE FCST AREA WILL STILL BE UNDER THE INFLUENCE OF
THE UPPER LEVEL LOW CENTERED OVER S-CNTRL QUEBEC. IN THE CYCLONIC
FLOW ANOTHER PIECE OF SHORT-WAVE ENERGY WILL SWING ACROSS UPSTATE
NY AND NEW ENGLAND. THE BEST CHC OF ISOLD-SCT SHOWERS DUE TO THE
CYCLONIC VORTICITY ADVECTION WILL BE NORTH AND WEST OF THE
CAPITAL REGION. H500 TEMPS WILL BE AROUND -15C TO -18C FROM ALY
NORTH AND WEST. THE H500 HEIGHTS ARE ABOUT 2-3 STD DEVS BELOW
NORMAL BASED ON THE LATEST GEFS FOR WED. H850 TEMPS WILL BE 1-2
STD DEVS BELOW NORMAL. HIGHS ON WED WILL BE IN THE M60S TO L70S
OVER THE MTNS...AND MID AND U70S IN THE VALLEYS...WITH A FEW 80F
READINGS NEAR KPOU. CLEARING SKIES AND LIGHT TO CALM WINDS WILL
ALLOW FOR COOL NIGHT FOR THE FIRST WEEK OF AUG...WITH HIGH
PRESSURE BUILDING IN. LOWS WILL RANGE FROM THE U40S TO M50S OVER
THE FCST AREA.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
BELOW NORMAL TEMPERATURES EXPECTED WITH HIGHS MAINLY IN THE 70S.

GUIDANCE IS IN GENERAL AGREEMENT THAT A COLD FRONT SHOULD STALL TO OUR
SOUTH LATE IN THE WEEK SOMEWHERE ACROSS THE MID ATLANTIC REGION. THE EXACT
LOCATION IS VERY MUCH IN QUESTION AT THIS TIME. GUIDANCE IS ALSO IN
GENERAL AGREEMENT THAT A LARGE UPPER LEVEL LOW WILL MOVE NORTH OF THE
CANADIAN MARITIMES LATE IN THE WEEK LEAVING THE GREAT LAKES REGION AND
NORTHEAST UNDER A LONGWAVE TROUGH THOUGH THE WEEKEND.

THE DIFFERENCES IN THE MODELS ARE ON HOW THEY HANDLE SHORT WAVE ENERGY
MOVING THROUGH THE LONGWAVE TROUGH AND ITS IMPACTS THE POSITION OF THE
STALLED BOUNDARY AND THE STRENGTHEN OF AN AREA OF LOW PRESSURE THAT IS
EXPECTED TO FORM AND MOVE EASTWARD ALONG THE BOUNDARY. GUIDANCE HAVE NOT
BEEN SHOWING ANY CONSISTENCY. AT THIS TIME...THE OPERATIONAL RUN OF THE GFS
KEEPS THE BOUNDARY...LOW AND PRECIPITATION SHIELD TO OUR SOUTH WHILE THE
ECMWF BRINGS A SOAKING RAINFALL TO THE AREA LATE THURSDAY NIGHT AND FRIDAY
TO MAINLY TO AREAS SOUTH OF INTERSTATE 90.

HAVE FAVORED GUIDANCE FROM THE WEATHER PREDICTION CENTER TO MAINTAIN
FORECAST CONSISTENCY AND HAVE CHANCE POPS FOR AREAS SOUTH OF I-90 LATE
THURSDAY NIGHT AND FRIDAY. AS FOR THE WEEKEND...HAVE MAINLY SLIGHT CHANCES
POPS SINCE THE TIMING OF ADDITIONAL SHORT WAVES IN HIGHLY UNCERTAIN.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
A PERIOD OF SHOWERS AND THUNDERSTORMS IS EXPECTED TO IMPACT THE
TAF SITES AS A COLD FRONT APPROACHES THE REGION LATE THIS AFTERNOON
AND EVENING. CONDITIONS WILL BE FAVORABLE FOR THE POSSIBILITY FOR
SOME STRONG TO SEVERE THUNDERSTORMS.

VFR CONDITIONS ARE EXPECTED WELL INTO THE AFTERNOON HOURS WITH
CONDITIONS LOWERING TO MVFR WITH THE CONVECTION LATE THIS AFTERNOON
AND EVENING. IFR CONDITIONS WILL BE POSSIBLE BUT HAVE NOT BEEN INCLUDE
IN THE TAFS AT THIS TIME. HAVE ADDRESSED THE THREAT OF THE STORMS WITH
A PROB30 GROUP INCLUDING THUNDERSTORMS. FOG IS EXPECTED TO DEVELOP LATE
TONIGHT AS THE CLOUD COVER DECREASES AND WINDS LIGHTEN UP.

AT KALB...SOUTHERLY WINDS WILL CONTINUE AND ARE EXPECTED TO BECOME GUSTY.
AT THE OTHER TAF SITES...A SOUTH TO SOUTH-SOUTHWEST WIND WILL DEVELOP
WHICH WILL BECOME GUSTY AHEAD OF THE COLD FRONT DURING THE DAY. A LIGHTER
SOUTHERLY FLOW IS EXPECTED IN THE WAKE OF THE STORMS AS WE HEAD INTO THE
OVERNIGHT HOURS.

OUTLOOK...
TUE NIGHT-THU: NO OPERATIONAL IMPACT. NO SIG WX.
THU NIGHT-FRI: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.

&&

.FIRE WEATHER...
A COLD FRONT WILL APPROACH FROM THE EASTERN GREAT LAKES
REGION TODAY WITH A CHANCE OF SHOWERS AND THUNDERSTORMS. THE COLD
FRONT WILL BE EAST OF THE REGION TUESDAY MORNING...BUT AN UPPER
LEVEL DISTURBANCE WILL CONTINUE THE THREAT FOR SCATTERED SHOWERS
AND THUNDERSTORMS TUESDAY AFTERNOON...AS COOLER AND DRIER AIR WILL
ARRIVE FOR WEDNESDAY.

THE RH VALUES WILL LOWER TO 40 TO 60 PERCENT THIS AFTERNOON...AND
INCREASE TO 75 TO 100 PERCENT TONIGHT. THE RH VALUES WILL LOWER TO
35 TO 55 PERCENT TUESDAY AFTERNOON.

THE WINDS WILL BE FROM THE SOUTH TO SOUTHWEST AT 10 TO 20 MPH
TODAY...AND SOUTH TO SOUTHWEST AT 5 TO 15 MPH TONIGHT. THE WINDS
WILL BE FORM THE WEST TO NORTHWEST AT 10 TO 20 MPH ON TUESDAY WITH
THE FRONT MOVING ACROSS THE REGION.

&&

.HYDROLOGY...
MAINLY DRY WEATHER IS EXPECTED THIS MORNING WITH SHOWERS AND
THUNDERSTORMS EXPECTED THIS AFTERNOON AND EVENING AS A COLD FRONT
APPROACHES AND CROSSES THE REGION. THE STORMS WILL BE CAPABLE OF
PRODUCING LOCALLY HEAVY DOWNPOURS AS PWATS RISE UP TO AROUND 1.5
INCHES AHEAD OF THE BOUNDARY. THE HEAVY RAINFALL COULD LEAD TO
SOME MINOR FLOODING IN POOR DRAINAGE AND LOW LYING AREAS. ALSO
SOME SHARP WITHIN BANK RISES WOULD BE EXPECTED ON STREAMS...CREEKS
AND SOME SMALL RIVERS.

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED ON
TUESDAY ESPECIALLY DURING THE AFTERNOON AS THE UPPER LEVEL TROUGH
AXIS APPROACHES AND PASSES OVER THE REGION. RAINFALL AMOUNTS MAY
RANGE FROM A TENTH TO A THIRD OF AN INCH WITH LOCALLY HIGHER
AMOUNTS.

A TREND TOWARDS DRIER WEATHER WILL OCCUR ON WEDNESDAY...AND
CONTINUE UNTIL FRIDAY MORNING.

FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEBSITE.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.

&&

$$
SYNOPSIS...WASULA
NEAR TERM...WASULA
SHORT TERM...WASULA
LONG TERM...IAA
AVIATION...IAA
FIRE WEATHER...BGM/WASULA
HYDROLOGY...BGM/WASULA


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