Flash Flooding and Hail in New York, May 29, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BINGHAMTON NY
159 PM EDT WED MAY 29 2013

.SYNOPSIS...
A WARM FRONT LIFTING NORTH THROUGH THE AREA WILL BE ACCOMPANIED BY
CHANCES OF SHOWERS AND THUNDERSTORMS TODAY. SOME STORMS COULD
CONTAIN GUSTY WINDS AND HEAVY RAINFALL. WE WILL EXPERIENCE DRIER
WEATHER THURSDAY AND FRIDAY BUT IT WILL BE HOT WITH TEMPERATURES
WELL INTO THE 80S TO NEAR 90. THUNDERSTORM CHANCES WILL INCREASE
AGAIN OVER THE WEEKEND...ESPECIALLY SUNDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
1130 AM UPDATE...
NO CHGS NEEDED AT THIS TIME AS CONVECTIVE DVLPMNT RMNS IN QUESTION
FOR THIS AFTN. INITIAL BATCH OF RAIN HAS MVD EAST OF THE AREA WITH
MORE DVLPMNT BACK TO THE WEST ACRS LK ERIE IN ADVANCE OF APPCH
S/WV. SUN HAS BROKEN THRU ACRS WRN ZONES AS OF 15Z WITH
DESTABILIZATION NOW OCCURRING AND SBCAPE APPCHG 1000 J/KG ALONG
WITH 0-6KM BULK SHEAR VALUES OF 40-45KTS. WL WAIT FOR THIS WV TO APPCH
CNTRL NY BFR DVLPMNT LKLY TO OCCUR AFT 18Z. THREAT CONTS FOR
BROKEN LINE WITH DAMAGING WIND GUSTS ALONG WITH ISOLD HAIL. HV
TWEAKED HRLY T/TD/POP AND SKY GRIDS TO ACCNT FOR CURRENT TRENDS.

715 AM UPDATE...
REMAINS OF ONE CONVECTIVE COMPLEX RAINED OUT OVERNIGHT.
MEANWHILE...WARM SECTOR IS SURGING NORTHWARD /ESPECIALLY JUST OFF
THE SURFACE/...AND WEAK UPPER WAVES ON TOP OF THAT BUILDING SECTOR
IS HELPING TO INITIATE NARROW LINES OF ELEVATED SHRA-TSRA OVER OUR
REGION. WITH INCREASING ELEVATED INSTABILITY...THIS ACTIVITY WILL
CONTINUE TO CARRY EAST ESPECIALLY ACROSS NORTHERN FINGER LAKES
THROUGH NY THRUWAY CORRIDOR/MOHAWK VALLEY EARLY THIS MORNING.

ATTENTION THEN TURNS TO EXPECTED NEW CONVECTIVE DEVELOPMENT TODAY.
TIMING OF ASSOCIATED STRONGER SHORTWAVE HAS MOVED UP A FEW
HOURS...AND SO I EXPECT NEW THUNDERSTORMS TO DEVELOP FAIRLY EARLY
DURING MIDDAY AND THEN SWEEP ACROSS GOOD CHUNK OF THE AREA THIS
AFTERNOON. DESPITE WARM FRONT MAKING GOOD NORTHWARD PROGRESS...AND
THUS CONVECTIVE CAP TRYING TO GET ESTABLISHED...THE SHORTWAVE
PASSAGE SHOULD ERODE CAP WITHIN NORTHERN EDGE OF WARM SECTOR
ALLOWING CONVECTIVE INITIATION. MESOSCALE BOUNDARIES AND
ADDITIONAL SHORTWAVES WILL LIKELY LEAD TO CONVECTION NOT BEING A
CLEAN LINE BUT INSTEAD BEING A COUPLE CLUSTERS OR SMALL LINES.

GOOD UNIDIRECTIONAL SHEAR ENVIRONMENT WITH 35-45 KT FLOW
THROUGHOUT 2-6KM LAYER WILL POSE THREAT FOR DAMAGING WINDS WITH
THE THUNDERSTORMS THIS AFTERNOON...AS PER CONTINUED SLIGHT RISK
DEPICTED BY STORM PREDICTION CENTER. THERE IS A QUESTION AS TO HOW
MUCH COVERAGE OF THUNDERSTORMS WE WILL HAVE WITH THE QUICKER
TIMING OF THE MAIN WAVE...THAT IS...IT MAY BE FAIRLY
CAPPED/SCATTERED INITIALLY MIDDAY BEFORE CONSOLIDATING ON ITS WAY
THROUGH THE AREA THIS AFTERNOON. ANOTHER POINT OF CONCERN IS THAT
THERE WILL BE SOME TURNING IN THE LOWER PORTION OF THE SOUNDING UP
TOWARDS THE MOHAWK VALLEY...WHICH IS OFTEN THE CASE FOR A SHALLOW
LIFTING WARM FRONT. SO WHILE DAMAGING WIND IS THE MAIN
THREAT...LARGE HAIL AND AN ISOLATED TORNADO CANNOT BE RULED OUT
TOWARDS THE NORTHEASTERN ZONES. 0-6KM BULK SHEAR VALUES OF 40-50
KTS SHOWS UP IN THE NAM AT 18Z IN THE NORTHERN PORTIONS OF OUR
AREA...SUGGESTING POSSIBILITY OF SPLITTING SUPERCELLS IF ENOUGH
INSTABILITY IS REALIZED. LASTLY...PRECIPITABLE WATER VALUES EXCEEDING
AN INCH-AND-A-HALF ALSO SUGGESTS THAT STORMS WILL BE CAPABLE OF
HEAVY DOWNPOURS. LACK OF MID LEVEL DRY AIR MAY LIMIT COLD POOL
DOWNDRAFT PRODUCTION...BUT AMOUNT OF OVERALL SHEAR WILL STILL KEEP
AT LEAST THE SLIGHT RISK OF DAMAGING WINDS REGARDLESS.

WITH THE WARM SECTOR SURGING NORTHWARD...TEMPERATURES
SIGNIFICANTLY WARMER COMPARED TO TUESDAY. JUST PART OF THE TREND
TOWARDS THE INBOUND HEAT FOR LATER THIS WEEK.

CONVECTION QUICKLY WANES INTO TONIGHT. BREAKS IN THE SKY MAY ALLOW
FOR PATCHY FOG OR LOW STRATUS TO FORM TONIGHT...FOR PLACES RECEIVING
A GOOD AMOUNT OF RAINFALL DURING THE DAY.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
THE WARMEST AIRMASS OF THE SEASON SO FAR PROGGED TO ARRIVE DURING
THIS PERIOD AS MID-LEVEL RIDGE AXIS CONTINUES TO BUILD OVERHEAD.
QUICK GLANCE AT CTP ANOMALY GRAPHICS OFFERS 500-HPA HEIGHTS OF 1-2
STANDARD DEVIATIONS ABOVE NORMAL BEGINNING ON THURSDAY AS UPPER
TROUGH CLOSES OFF OVER THE NORTHERN PLAINS AND INCREASES HEIGHTS
DOWNSTREAM. 850-HPA TEMPS BY THURSDAY QUICKLY APPROACH 16C ACROSS
THE AREA WHICH SHOULD SUPPORT MID TO UPPER 80S...WITH LOW 90S NOT
OUT OF THE QUESTION ACROSS THE LOWER WYOMING AND CHEMUNG RIVER
VLYS. BY FRIDAY...SOUTHWEST FLOW TO RETURN TO THE AREA AS
AFOREMENTIONED UPPER LOW SLOWLY SLIDES EAST INTO THE UPPER MISS
VLY. AS THIS OCCURS...850-HPA TEMPS OF ROUGHLY 18C (1-2 STANDARD
DEVIATIONS ABOVE NORMAL) COMBINED WITH DOWNSLOPE COMPRESSIONAL
WARMING ACROSS FAVORED LOCATION SHOULD SUPPORT EVEN WARMER TEMPS
WITH HIGHS EASILY SOARING INTO THE UPPER 80S AND LOWER 90S. WITH
RESPECT TO PRECIP CHANCES...BOTH WRF AND GFS OFFER DIURNAL SHWR
ACTIVITY ACROSS PORTIONS OF THE AREA BY FRI AFTERNOON BUT WITH NO
APPRECIABLE FORCING MECHANISM TO SPEAK OF...HAVE ELECTED TO
MAINTAIN A DRY FCST FOR NOW.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
1230 PM UPDATE...

AN EARLY EXTENDED DISCUSSION TODAY WITH THE ANTICIPATION OF SEVERE
WEATHER THIS AFTERNOON. NO MAJOR CHANGES FROM THE EXCELLENT
FORECAST AND DISCUSSION OVERNIGHT. MAIN FOCUS IN THE LONG TERM IS
THE SEVERE WEATHER THREAT SUNDAY...WITH SPC PLACING OUR AREA IN
THE DAY 5 OUTLOOK. IN ADDITION TO THE SEVERE WEATHER THREAT...WITH
A DEEP MOISTURE FEED BACK TOWARD THE GULF OF MEXICO....LOCALLY
HEAVY RAIN IS POSSIBLE. BEHIND THE COLD FRONT COOLER AND DRIER
WEATHER BUILD IN FOR MOST OF NEXT WEEK.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
18Z UPDATE...
BROKEN LINE OF SHOWERS AND THUNDERSTORMS ARE POSSIBLE BETWEEN 19Z
AND 23Z TODAY. HAVE INCLUDED A 2 HOUR TEMPO GROUP IN THE TAF SITES
TO COVER FOR THESE... BUT THERE HAS BEEN NO DEVELOPMENT THROUGH
1730Z SO TIMING IS VERY UNCERTAIN AT THIS TIME. SKIES WILL BE
CLEAR TO PARTLY CLOUDY WITH MOSTLY VFR THIS EVENING INTO EARLY
THURSDAY MORNING... THEN A PERIOD OF MVFR OR BRIEF IFR IS POSSIBLE
IN SCATTERED AREAS OF LOW CLOUD OR FOG AROUND SUNRISE. CONDITIONS
WILL IMPROVE TO VFR ALL AREAS BY MID-MORNING THURSDAY.

WINDS WILL BE SOUTHWEST AT 5 TO 15 KTS WITH A FEW HIGHER GUSTS
THIS AFTERNOON... ESPECIALLY NEAR ANY THUNDERSTORMS... THEN
VARIABLE AT LESS THAN 10 KTS TONIGHT.

OUTLOOK...

THU THROUGH FRI NIGHT...MAINLY VFR.

SAT/SUN...POTENTIAL FOR MVFR IN SHRA/TSRA AS COLD FRONT
APPROACHES...MAINLY SUNDAY.

&&

.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...NONE.

&&

SYNOPSIS...MDP
NEAR TERM...KAH/MDP/PVN
SHORT TERM...CMG
LONG TERM...HEDEN
AVIATION...MSE

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BINGHAMTON NY
322 PM EDT WED MAY 29 2013

NYZ009-015>018-022>025-036-037-044>046-055>057-062-PAZ038>040-043-
044-047-048-072-301930-
NORTHERN ONEIDA-YATES-SENECA-SOUTHERN CAYUGA-ONONDAGA-STEUBEN-
SCHUYLER-CHEMUNG-TOMPKINS-MADISON-SOUTHERN ONEIDA-CORTLAND-CHENANGO-
OTSEGO-TIOGA-BROOME-DELAWARE-SULLIVAN-BRADFORD-SUSQUEHANNA-
NORTHERN WAYNE-WYOMING-LACKAWANNA-LUZERNE-PIKE-SOUTHERN WAYNE-
322 PM EDT WED MAY 29 2013

...SEVERE THUNDERSTORM WATCH 241 IN EFFECT UNTIL 11 PM EDT THIS
EVENING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NEW
YORK...SOUTHEASTERN NEW YORK AND NORTHEAST PENNSYLVANIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   SEVERE THUNDERSTORM WATCH.

WITH A MOIST ATMOSPHERE...THUNDERSTORMS MAY ALSO PRODUCE HEAVY
RAINFALL...CAUSING PONDING ON ROADWAYS AND OTHER AREAS OF POOR
DRAINAGE.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

AFTER SEVERAL HOT DAYS THURSDAY THROUGH SATURDAY...WE MAY HAVE A
FAVORABLE SET UP FOR SEVERE WEATHER AS A COLD FRONT PASSES SUNDAY
INTO SUNDAY NIGHT. BEING SEVERAL DAYS AWAY...THE DETAILS OF THIS
POTENTIAL EVENT ARE STILL UNCERTAIN. MONITOR THE FORECAST FOR
UPDATES IN COMING DAYS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL LIKELY BE NEEDED THIS AFTERNOON.

PN

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE BINGHAMTON NY
428 PM EDT WED MAY 29 2013

NYZ017-018-036-044-045-292115-
CAYUGA NY-CHENANGO NY-CORTLAND NY-MADISON NY-ONONDAGA NY-
428 PM EDT WED MAY 29 2013

...STRONG THUNDERSTORM WILL AFFECT EXTREME SOUTHEASTERN CAYUGA...
NORTHERN CORTLAND...NORTHWESTERN CHENANGO...SOUTHEASTERN ONONDAGA AND
SOUTHWESTERN MADISON COUNTIES...

* AT 426 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  STRONG THUNDERSTORM CAPABLE OF PRODUCING SMALL HAIL...STRONG GUSTY
  WINDS...AND VERY HEAVY RAIN.  THIS STORM WAS LOCATED NEAR SCOTT...
  AND MOVING EAST AT 40 MPH.

* THE STRONG THUNDERSTORM WILL BE NEAR...
  BALTIMORE AND TULLY AT 435 PM EDT...
  TRUXTON AND APULIA AT 440 PM EDT...
  TRIPOLI AND CUYLER AT 445 PM EDT...
  DERUYTER AND DE RUYTER AT 450 PM EDT...
  SHEDS AND LINCKLAEN AT 455 PM EDT...
  GEORGETOWN AND OTSELIC AT 505 PM EDT...
  LEBANON AND SOUTH LEBANON AT 510 PM EDT...
  EATON AND SMYRNA AT 515 PM EDT...

IF ON OR NEAR A BODY OF WATER..SEEK SHELTER NOW. GET OUT OF THE
WATER AND MOVE INDOORS OR INSIDE A VEHICLE.

LAT...LON 4286 7558 4266 7552 4264 7630 4282 7632

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DJN