078
FXUS61 KALY 091104
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
700 AM EDT WED JUL 9 2008
SYNOPSIS
A BERMUDA HIGH PRESSURE SYSTEM WILL CONTROL OUR WEATHER
THROUGH EARLY THIS MORNING. THEN...A SLOW MOVING PRE FRONTAL
TROUGH...PRECEDING THE MAIN COLD FRONT...WILL APPROACH FROM THE WEST
DURING THE MID DAY HOURS TODAY. BOTH OF THESE FRONTAL
SYSTEMS WILL BRING SHOWERS AND THUNDERSTORMS TO THE REGION. COOLER
AND DRIER CANADIAN AIR WILL FOLLOW THROUGH FRIDAY.
NEAR TERM /THROUGH TONIGHT/
POTENTIAL FOR THUNDERSTORMS STILL HIGH TODAY INTO THIS EVENING
ALTHOUGH SEVERE THREAT WILL MAINLY BE CONFINED TO AREAS FROM
HUDSON VALLEY EAST WHERE SPC HAS THIS AREA IN A SLIGHT RISK
FOR SEVERE THUNDERSTORMS TODAY WITH THE POTENTIAL FOR WET
MICROBURSTS. OTHER CONCERN WILL BE POSSIBLE LOCALIZED FLOODING AS
PWATS RISE TO ABOVE 2 INCHES THIS AFTERNOON ACROSS SOUTHEAST THIRD
OF FA.
HIRES WRF COMPOSITE REFLECTIVITY HAS LEADING EDGE OF ORGANIZED
LINE OF CONVECTION MOVING INTO WESTERN PORTION OF FA BTWN 12Z AND 13Z
THIS CONVECTION WILL RESULT IN LIMITED SURFACE HEATING ACROSS
NORTHERN AND WESTERN THIRD OF FA WHICH MAY PRECLUDE SEVERE
THUNDERSTORM DEVELOPMENT. SOUTHERN AND EASTERN TWO THIRDS OF FA ON
THE OTHER-HAND EXPECTED TO HAVE SOME HEATING THROUGH THE MID TO
LATE MORNING HOURS WITH SBCAPES EXPECTED TO REACH 1000-1500 J/KG
FROM HUDSON VALLEY SOUTH AND EAST THIS AFTERNOON AS 0-3 KM
HELICITY VALUES BRIEFLY RISE INTO 80 TO 120 RANGE WITH STRONG
THETA E RIDGE H10-H8 AND PWATS EXCEEDING 2 INCHES SOUTHEAST THIRD
OF FA. UNLIKE THE THUNDERSTORMS WHICH OCCURRED THE LAST TWO DAYS...THE
THUNDERSTORMS TODAY SHOULD MOVE AT 25-35 KTS BASED ON H7 STEERING
FLOW WITH MULTICELL LINES BEING THE MAIN THREAT AS CELLS TRACK FROM
SOUTHWEST TO NORTHEAST ALONG ONE OF MORE LINES WHICH ADVANCE FROM
WEST TO EAST. EMBEDDED SUPERCELLS...ALTHOUGH LESS LIKELY THAN
BEFORE DUE TO WEAKER SHEAR AND LOWER HELICITY ARE STILL POSSIBLE
MAINLY SOUTH OF ROUTE 23. H8 WIND MAX AT 25-30 KTS ACROSS WESTERN
NEW ENGLAND AND MID HUDSON VALLEY EARLY THIS AFTERNOON WHILE
CYCLONICALLY CURVED UPPER JET ACROSS SOUTHERN CANADA IN EXCESS OF
100 KTS PUTS FA IN FAVORABLE RR QUAD. MAGLENTA CALCULATION FOR
KALB...KGFL AND KPOU STILL CONTINUE TO SHOW MINOR SEVERE...THUS
THIS WEATHER SITUATION STILL NEEDS TO BE MONITORED CLOSELY. EXPECT
CONVECTION TODAY TO BE FAIRLY WIDESPREAD AND THUS HAVE GONE WITH
LIKELY TO CAT POPS.
AS FRONT SLIDES SOUTH AND EAST OF FA WEDNESDAY NIGHT...EXPECT COOLER
AND DRIER AIR TO WORK INTO FA WITH LOWS BY THURSDAY MORNING 10 TO
15 DEGREES LOWER THAN LOWS WEDNESDAY MORNING. ANY LINGER SHOWERS
AND THUNDERSTORMS SHOULD EXIT SOUTHEAST PORTION OF FA BY LATE THIS EVENING.
HAVE INCLUDED ENHANCED WORDING IN ZONES TODAY AND SOUTHEAST ZONES
THIS EVENING CALLING FOR HEAVY DOWNPOURS...FREQUENT LIGHTNING AND
GUSTY WINDS. WILL HIGHLIGHT THE SEVERE THREAT AS WELL AS POTENTIAL
FOR HEAVY RAIN IN HWO AND SPLIT HWO ALONG OR FAIRLY CLOSE TO
SLIGHT RISK AREA...MENTIONING SPOTTER ACTIVATION MAYBE NEEDED FROM
HUDSON VALLEY EAST.
AS FOR TEMPS WENT CLOSE TO MAV GUIDANCE TODAY AND TONIGHT.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
DRY WEATHER EXPECTED THURSDAY THROUGH FRIDAY NIGHT AS A RIDGE OF
HIGH PRESSURE SETS UP ACROSS FA BEING CENTERED ACROSS FA BY LATE
THURSDAY NIGHT INTO FRIDAY AND THEN MOVING TO EASTERN SEABOARD
LATE FRIDAY NIGHT. THIS WILL RESULT IN COOLER AND DRIER AIR ACROSS
THE FA WITH TEMPS SEVERAL DEGREES BELOW NORMAL AND MUCH LOWER
HUMIDITY.
FOR THE MOST PART HAVE GONE SEVERAL DEGREES BELOW MAV TEMPS DURING
THIS PERIOD WITH GOOD RATIONAL COOLING EXPECTED THURSDAY NIGHT AND
FRIDAY NIGHT.
LONG TERM /SATURDAY THROUGH TUESDAY/
MODELS ARE IN FAIRLY GOOD AGREEMENT ACROSS THE EASTERN UNITED
STATES THROUGH THE WEEKEND. A WEAK RIDGE ABOVE A SURFACE HIGH
OVER THE SOUTHEASTERN STATES DOMINATES THE WEATHER SATURDAY
WITH INCREASING HEAT AND HUMIDITY. HIGHS SATURDAY WILL BE
IN THE UPPER 80S WITH DEWPOINTS IN THE MID 60S. A SURFACE
LOW MOVING ACROSS SOUTHERN CANADA DRAGS A COLD FRONT THROUGH
THE REGION SUNDAY NIGHT. THIS IS FOLLOWED BY PASSAGE OF THE
UPPER TROF MONDAY RESULTING IN A CONTINUED CHANCE OF CONVECTION
MONDAY. UPPER TROF LIFTS OUT AS A SURFACE HIGH BUILDS OVER THE
REGION TUESDAY. TEMPERATURES BECOME MORE PLEASANT DURING THE
NEW WEEK WITH HIGHS FROM THE LOW 70S TO THE LOW 80S AND
LOWS AND DEWPOINTS NEAR 60 IN THE VALLEYS AND IN THE 50S
OVER THE HIGHER TERRAIN.
AVIATION /08Z WEDNESDAY THROUGH SUNDAY/
MVFR TO IFR FLIGHT CONDITIONS DUE TO FOG IN THE PREDAWN HOURS
WILL SLOWLY IMPROVE TO VFR BETWEEN 1300 AND 1500 GMT. VISIBILITY
WILL CONTINUE TO BE IMPARED BY HAZE. VFR CONDITIONS WILL THEN
PREVAIL INTO MID AFTERNOON...WITH SHOWERS AND THUNDERSTORMS
BECOMING MORE NUMEROUS AS THE AFTERNOON GOES ON. CIGS WILL GET CLOSE
TO OR BELOW MVFR WITH MVFR TO IFR VISIBILITY AT TIMES IN HEAVY RAIN
SHOWERS. WINDS WILL BE SOUTH TO SOUTHWEST AND GUST TO 15 KNOTS...
WITH HIGHER GUSTS POSSIBLE IN/NEAR THUNDERSTORMS. SHOWERS AND THUNDER
STORMS WILL DIMINISH FOLLOWING THE FRONTAL PASSAGE DURING THE LATE
AFTERNOON AND EARLY EVENING HOURS...WITH CLEARING FROM WEST TO EAST
LATER TONIGHT.
OUTLOOK...
FRIDAY...VFR...NO SIGNIFICANT WX.
SAT...VFR...POSS MAINLY ISOLD -SHRA.
SUN...VFR/MVFR...CHC -SHRA/TSRA.
FIRE WEATHER
VERY WARM AND HUMID AIR WILL REMAIN IN PLACE ACROSS THE REGION
THROUGH THIS EVENING. SHOWERS AND THUNDERSTORMS WILL BECOME MORE
NUMEROUS TODAY WITH THE MOST WIDESPREAD ACTIVITY THIS AFTERNOON.
ALL AREAS ARE EXPECTED TO RECEIVE RAINFALL WITH LOCALIZED AMOUNTS
OVER 2 INCHES...AS A RESULT WET FLAG CONDITIONS ARE EXPECTED THIS
AFTERNOON INTO THIS EVENING AHEAD OF A STRONG COLD FRONT WHICH
WILL MOVE THROUGH THE AREA.
RELATIVE HUMIDITY VALUES WILL ONLY FALL TO 55 TO 75 PERCENT
TODAY...INCREASE TO 100 PERCENT TONIGHT AND FALL TO 45 TO 60
PERCENT ON THURSDAY.
SOUTHWEST WINDS OF 5 TO 15 MPH WILL SHIFT TO WEST LATE TODAY OR
THIS EVENING. NORTH TO NORTHWEST WINDS OF 5 TO 10 MPH ARE EXPECTED
OVERNIGHT WITH WEST TO NORTHWEST WINDS OF 10 TO 20 MPH WITH HIGHER
GUSTS ON THURSDAY.
HYDROLOGY
A SULTRY AIR MASS WILL BRING ABOUT THE POSSIBILITY OF TORRENTIAL
RAINFALL TODAY...ESPECIALLY IN THE AFTERNOON AND EVENING HOURS
AS AN APPROACHING COLD FRONT PROVIDES A FOCUS FOR CONVECTION.
THE ALY SOUNDING LAST EVENING HAD A PWAT OF 1.7 INCHES. 700 HPA
STEERING WINDS WILL BE WSW 20 TO 30 KNOTS...SO CELLS WILL MOVE
BUT TRAINING AND BACKBUILDING COULD RESULT IN BANDS OF RAINFALL
EXCEEDING 1.5 INCHES IN A SHORT TIME PERIOD WHICH WOULD RESULT
IN FLOODING OF ROADS AND PARKING AREAS DURING AND FOR A SHORT
TIME AFTER THE DOWNPOUR. SMALL STREAMS IN THE AREAS OF HEAVY RAIN
COULD ALSO OVERFLOW. LARGER STREAMS COULD EXPERIENCE SHARP RISES
TO NEAR BANKFULL. THE LARGER RIVERS WILL NOT BE IMPACTED AS MUCH
SINCE THE HEAVY RAIN IS LIKELY TO FALL ON ONLY A SMALL PART OF THE
DRAINAGE. THE STORMS WILL BE MOST LIKELY DURING THE AFTERNOON AND
EARLY EVENING HOURS. ONCE THE FRONT PASSES THROUGH THE WEATHER WILL
BE DRY UNTIL NEXT SUNDAY WHEN ANOTHER FRONTAL SYSTEM WILL AGAIN
BRING ABOUT A POSSIBILITY OF SHOWERS AND THUNDERSTORMS...FOLLOWED
BY MORE DRY WEATHER NEXT WEEK. THE WATER LEVEL IN MOST OF THE
RESERVOIRS IN THE REGION IS DECLINING BUT THE ONLY RESERVOIR WITH A
LOW WATER LEVEL IS SCHOHARIE WHICH IS NORMALLY DRAINED OFF FAIRLY
RAPIDLY. THE LEVEL OF THE WATER TABLE IS ALSO SLOWLY DECLINING
WHICH IS NORMAL FOR THIS TIME OF THE YEAR.
ALY WATCHES/WARNINGS/ADVISORIES
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
SYNOPSIS...11
NEAR TERM...11
SHORT TERM...11
LONG TERM...RCK
AVIATION...RCK
FIRE WEATHER...11
HYDROLOGY...RCK
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