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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KALY 220721
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
321 AM EDT WED MAY 22 2013

.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM THE GREAT LAKES REGION TODAY INTO THE
SAINT LAWRENCE VALLEY THURSDAY. WARM HUMID CONDITIONS WILL PERSIST
INTO THURSDAY WITH SHOWERS AND THUNDERSTORMS. THURSDAY A STRONG
COLD FRONT WILL PUSH SLOWLY THROUGH NEW YORK AND NEW ENGLAND. LOW
PRESSURE WILL FORM ALONG THIS FRONT ON THE COAST FRIDAY...AS MUCH
COLDER AIR POURS INTO THE REGION. FRIDAY NIGHT THE STORM WILL MOVE
OFFSHORE AS HIGH PRESSURE BUILDS INTO THE GREAT LAKES REGION FOR
THE MEMORIAL DAY WEEKEND. IT WILL BRING FAIR WEATHER WITH
UNSEASONABLY COOL TEMPERATURES FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
LINE OF THUNDERSTORMS EAST OF I-88 CORRIDOR MOVING THROUGH FCA
ATTM. MAINLY HEAVY RAIN AND FREQ LIGHTNING. AREAS OF MODERATE RAIN
EXTEND BEHIND IT.

MOST AREAS TO BE IMPACTED WILL SEE ANOTHER 0.5 TO 1.O INCH OF RAIN
BRINGING TOTALS FOR TODAY UP TO 2-3 INCHES IN MOST AREAS IMPACTED
WITH SOME ISOLD 4 INCH AMOUNTS. AREAL FLOOD ADVISORY HAS BEEN
ISSUED FROM MHWK VLY AND ADJACENT AREAS INTO S VT/BERKSHIRE COUNTY
FOR OVERNIGHT TO COVER ANY SMALL STREAM AND URBAN FLOODING.

THIS LINE SHOULD EXIT MOST OF UPSTATE NY/VT AND W MA NEXT 1.5 TO
2 HRS...EXCEPT CATSKILLS AND MID HUDSON VLY WHERE IT IS JUST
ARRIVING IN AREAS THAT HAVE NOT HAD MUCH PCPN AT ALL OR SINCE
SINCE LATE TUES AFTN. IT SHOULD THEN DIMINISH AND END OVERNIGHT

AT SFC WMFNT IS LIFTING NE THROUGH FCA OVERNIGHT AND WILL BE ALONG
N TIER OR N OF RGN WED MRNG. IT WILL MOVE TO ST LAWRENCE VLY TO
MICHIGAN LINE...AS WEAK LOW PRESSURE FORMS ALONG AND PROPAGATES UP
IT TODAY. THIS LEAVES FCA IN WARM SECTOR WITH ALOT OF RESIDUAL
LLVL MOISTURE/CLOUDS FM TUES CONVECTION

WITH TD IN 60S...TEMPS REBOUNDING TO 80S...VRBL CLOUDS THE THREAT
OF TSTMS INCREASES THROUGH THE DAY. LOCAL WRF/HRRR WHICH HANDLED
TODAYS EVENT WELL...SHOW A MAINLY CELLULAR AND PULSE RESPONSE
TODAY IN SIMULATED REFL. GFS PRODUCES SFC CAPES ON THE ORDER OF
1000-2000 J/KG THE NAM 2000-4000 J/KG WITH A DEFINE PREFERENCE
FROM THE CAPITAL DISTRICT S & E AND THE MHWK VLY.

NAM AND GFS SHOW H850-700 LAPSE RATES AROUND 6.5 THIS AFTN.

GOING TO HRRR FOR THE LATE AFTN:

POU/ALB/GFL
CAPE 2000/1812/1777
J/KG MAX WIND 33/33/40 EHI OF 1.6/1.5/1.2
STORM SPEED 24/18/18
SRH 175/156/106
MAGLENTA 1.75/2.17/2.44 ALL MAJOR SEVERE

WHICH IS CONSIDERABLY STRONGER LOOKING THAN HRRR REFL. THE NAM
MODEL SOUNDINGS AND WRF MODEL SOUNDINGS ARE CONSIDERABLY LOWER IN
CAPE AROUND 1000-1200 J/KG.

PWATS WILL CONTINUE TO RUN A FEW STANDARD DEVIATIONS ABOVE NORMAL
WITH VALUES OF 1.50-1.8 INCHES.

SOME OTHER CONSIDERATIONS LLVL JET AT H850 HPA IS 25-35KTS...AND
BULK OF IT MAY PASS WEST OF FCA. THERE IS LITTLE ADDITIONAL UPPER
FORCING.  SPC HAS OUTLOOKED NY PORTIONS OF FCA AT THIS POINT WILL
NOT TRY TO GET SPECIFIC...WILL GO WITH ENHANCED WORDING TODAY. IF
THERES A PREFERRED AREA IT WOULD MHWK VLY AND S...AND A PREFERRED
TIME OF LATER IN THE AFTN AND EVENING.

CONVECTION WILL CONTINUE INTO THE EVNG HOURS AND DIM OVERNIGHT AS
FCA IS FIRMLY IN WARM SECTION. LOWS AND TD WILL BE IN THE
60S...AND AREAS OF PATCHY FOG POSSIBLE IN THE MORNING.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
-- Changed Discussion --
THU AND THU NT 500HPA TROF STARTS MOVING E THROUGH GRTLKS AS SFC
LOW ORGANIZES ALONG SEMI-STALLED FRONT FROM FM LK ERIE UP ST
LAWRENCE VLY. THIS SYSTEM PUSHES SLOWLY EAST DRAGGING A CDFNT TO
BTV-SYR LINE THU AFTN...AND THROUGH FCA BY 12UTC FRI. NAM/GFS IN
PRETTY CLOSE AGREEMENT WITH THIS TIMING. WHILE THERE IS INCRG
DYNAMICS WITH APPROACHING JET AND TROF...CAPES 1000-1500 ...CLOUDS
WILL BE WIDESPREAD HOLDING MAX TEMPS TO MID 70S TO AROUND 80. SPC HAS
ONLY PUT AREA IN SEE TEXT ATTM...WITH LOW PROBS DUE TO LIMITED INSTABILITY.
REGARDLESS AREA WILL SEE PERIOD OF -SHRA/TSTMS INCRG THU...TRANSITIONING
TO -SHRA/-RA BEHIND THE CDFNT OVERNIGHT.

BY FRI MORNING CDFNT WILL BE IN I-95 CORRIDOR ALONG THE ATLC
COAST. 500HPA TROF WILL BE MOVING INTO NE USA...AND BOTH MODELS
DEVELOP A MODEST SFC LOW OVER NJ. THE WARMTH OF PAST FEW DAYS
WILL GIVE WAY TO A COOL BREEZY WITH -SHRA FRI. FINALLY SFC LOW
MOVES OFFSHORE FRI NT AS HIGH PRESSURE BUILDS INTO THE GRTLKS.
HWVR THE 500HPA TROF LINGERS AND CUTS OFF OVER NEW ENG SAT.
BETWEEN THESE TWO SYSTEMS A BRISK NW GRADIENT WILL DRIVE SOME
PRETTY COOL AIR INTO THE REGION FOR LATE MAY. WITH 500HPA CUT OFF
LINGERING SKIES MAY ONLY BE PS SAT IN GFS.

TEMPS WILL PROBABLY GO NOWHERE FRI...ONLY COMING OFF MORNING LOWS
A FEW DEG...OR HOLDING STEADY.

THE WEEKEND FCST IS DETERIORATING...
THE GFS IS PROGRESSIVE WITH SFC LOW DEPARTING THE COAST FRI
NT...WITH ITS 500 HPA TROF CROSSING REGION SAT AND DEPARTING SAT
NT WITH PC SKIES AND A RATHER BRISK WIND GRADIENT.

THE 00UTC ECMWF CUTS OFF THE 500HPA LOW OVER NJ...DEVELOPS A
COASTAL LOW...WHICH LINGERS ALONG THE EAST COAST FOR THE WEEKEND
WITH PERIODS OF RAW CHILLY RAIN.

THE GFS TEMPS WOULD BRING MINS SAT MORNING INTO THE MID 30S TO
MID 40S WITH SOME NEAR 30 AND POTENTIAL FROST/FREEZE ISSUES IN
ADRNDKS. HIGHS SAT WILL ONLY REBOUND EVEN WITH THE STRONG SUN TO
THE 60S. LOWS SAT NIGHT WOULD AGAIN BE IN THE 30S. WINDS WILL
REMAIN BRISK. ECMWF WOULD RESULT IN SLIGHTLY WARMER NIGHT TIME
TEMPS AND COOLER YET DAYTIME TEMPS IN MID 50S TO LOW 60S. HPC
LEANS TWRD A BLEND WITH CHC POPS LINGERING INTO SAT. IT WILL BE A
FALL LIKE MEMORIAL DAY WEEKEND.

WILL LEAN TWRD GFS/HPC BLEND THROUGH SAT. ATTM WILL MAKE NO
CHANGES BEYOND SAT NT TO MINIMIZE FLIP FLOPPING GIVEN THE SPREAD
IN MODELS SOLUTIONS ATTM.
-- End Changed Discussion --

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
-- Changed Discussion --
CANADIAN HIGH PRESSURE WILL BUILD INTO THE REGION SUNDAY. THE HIGH
WILL SHIFT EASTWARD ACROSS THE REGION AND OFFSHORE EARLY NEXT
WEEK. TEMPERATURES WILL GRADUALLY MODERATE AS THE HIGH SHIFTS TO
THE EAST WITH NEAR SEASONABLE TEMPERATURES FOR MONDAY.

THE GROWING SEASON IS UNDERWAY ACROSS THE MID HUDSON VALLEY...
GREATER CAPITAL DISTRICT...LAKE GEORGE SARATOGA REGION...THE MOHAWK
VALLEY...EASTERN CATSKILLS...TACONICS...BERKSHIRES...BENNINGTON AND
EASTERN WINDHAM COUNTIES VT AND LITCHFIELD COUNTY. IT WILL START ON
MAY 25TH FOR THE SOUTHERN ADIRONDACKS AND WESTERN WINDHAM COUNTY.
-- End Changed Discussion --

&&

.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
ACCOUNTING FOR CURRENT SHOWER AND THUNDERSTORM ACTIVITY THAT SHOULD
CONTINUE AT KGFL THROUGH ABOUT 06Z...AT KALB THROUGH ABOUT
07Z-08Z...AND KPSF THROUGH ABOUT 08Z.  SOME MVFR AND OCCASIONAL IFR
CONDITIONS IN THE SHOWERS AND THUNDERSTORMS.  SOME OTHER ISOLATED
THUNDERSTORMS WELL WEST OF THE AREA COULD APPROACH THE AREA BETWEEN
KALB AND KPOU THROUGH SUNRISE...BUT WITH CONTINUED STABILIZATION OF
THE ATMOSPHERE THE THUNDERSTORMS COULD DISSIPATE BY THEN.

ONCE THE RAIN ENDS EARLY THIS MORNING...THERE COULD BE PERIODS OF
MVFR FOG AND VFR CEILINGS...BUT SCATTERED CLOUDS COULD DEVELOP BELOW
1000 FEET. WILL HAVE TO MONITOR FOR ANY BETTER CLEARING TOWARD
SUNRISE THAT COULD RESULT IN IFR FOG AND/OR CEILINGS BELOW 1000
FEET.  FOR NOW NOT INDICATING ANY IFR CONDITIONS AT ANY TAF SITES
THROUGH THE EARLY MORNING HOURS...BUT WILL AMEND IF CONDITIONS AND
TRENDS CHANGE.

VFR CONDITIONS SHOULD PREVAIL THROUGH MOST OF THE DAY AFTER 12Z
UNTIL NEW CONVECTION DEVELOPS LATER IN THE AFTERNOON AND EVENING.
MIXED SIGNALS ABOUT WHERE THE CONCENTRATION OF THUNDERSTORMS WILL BE
LATER TODAY SO PUTTING VCSH IN ALL TAFS AFTER 22Z...BUT MORE
THUNDERSTORM ACTIVITY EXPECTED SCATTERED ACROSS THE REGION LATE
TOMORROW AFTERNOON AND EVENING.

WINDS SHOULD BE LIGHT SOUTH THROUGH SUNRISE...THEN BECOME VARIABLE
AT LESS THAN 10 KT THROUGH THE DAY TOMORROW...MAINLY SOUTH TO
SOUTHWEST. WINDS SHOULD BE LIGHT AGAIN TOMORROW EVENING. WINDS COULD
BE QUITE GUSTY IN THUNDERSTORMS TOMORROW AFTERNOON AND EVENING.

OUTLOOK...
WED...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY DURING THE AFTN.
WED NIGHT...VFR/MVFR. AT KGFL AND KALB -SHRA/-TSRA LIKELY. AT KPSF
AND KPOU CHC -SHRA/-TSRA.
THU...MVFR WITH IFR POSSIBLE. -SHRA/-TSRA LIKELY.
THU NIGHT...VFR/MVFR. CHC -SHRA/-TSRA ESPECIALLY IN THE EVNG.
FRI...MAINLY VFR. CHC -TSRA MAINLY IN THE AM.
SAT-SUN...VFR. NO SIG WX.

&&

.FIRE WEATHER...
NO FIRE WEATHER CONCERNS THROUGH FRIDAY. OCCASIONAL SHOWERS AND
THUNDERSTORMS WILL CONTINUE THROUGH THURSDAY NIGHT. SHOWERS WILL
CONTINUE INTO FRIDAY.

RH VALUES WILL INCREASE TO 85 TO 100 PERCENT TONIGHT...AND
THURSDAY NIGHT...AND LOWER TO 45 TO 60 PERCENT THIS AFTERNOON.

WINDS WILL MAINLY LESS THAN 10 MPH THROUGH TONIGHT...BECOMING
SOUTHWEST AROUND 10MPH THURSDAY.

&&

.HYDROLOGY...
PWATS ON THE ORDER OF 1.5 TO 2.0 INCHES NEXT FEW DAYS. WHILE
WIDESPREAD FLOODING IS NOT ANTICIPATED...LOCALLY HEAVY RAINFALL IN
THUNDERSTORMS AND TRAINING COULD RESULT IN SMALL STREAM AND URBAN
FLOODING OVERNIGHT AND AGAIN THIS AFTERNOON. SIGNIFICANT WITHIN
BANK RISES ARE LIKELY IN LARGER RIVERS.

3-HR ZONAL FFG VALUES ARE GENERALLY IN THE 2.5-3.0 INCH RANGE AT
THIS TIME...WHICH ARE HIGH FOR MID TO LATE MAY.

DUE TO THE SCATTERED NATURE OF THE SHOWERS AND THUNDERSTORMS...
BASIN AVERAGE QPF WILL BE HIGHLY VARIABLE THIS WEEK. THE BEST
THREAT FOR SEEING SIGNIFICANT AMOUNTS OF SHOWERS OR THUNDERSTORMS
WILL THIS AFTERNOON INTO THURSDAY NIGHT.

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...SNYDER
NEAR TERM...SNYDER
SHORT TERM...SNYDER
LONG TERM...IAA
AVIATION...NAS
FIRE WEATHER...SNYDER
HYDROLOGY...SNYDER