Heavy Rain in Vermont, August 30 to 31, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
937 PM EDT TUE AUG 30 2005

.SHORT TERM (REST OF TONIGHT)...

FLOOD WATCH CONTINUES...

CURRENT FORECAST ON TARGET WITH RAIN MOVING IN TOWARD/AFTER MIDNIGHT
SO NO CHANGES NEEDED.

REMAINS OF KATRINA JUST SOUTH OF CINCINNATI AT 00 UTC AND
RUC/GFS/12UTC GFS ENSEMBLES ALL WITH BETTER ANALYSIS/FORECAST OF
THE POSITION THAN THE NAM WHICH IS TOO SLOW. NAM CONTINUES TO LAG
THE GFS IN POSITION BY 170 MILES TO THE SOUTHWEST BY 12 UTC WED.
LATEST RUC SUPPORTS GFS/GFS ENSEMBLE WHICH HAS THE LOW CENTER
JUST NORTH OF ERI BY 12Z TOMORROW.

00 UTC RAOBS SHOW INCREASING PRECIPITABLE WATERS WITH OVER TWO
INCHES AT KALY/KOKX/KCHH. WARM CLOUD DEPTHS RUNNING 4.5 KM
INDICATE TROPICAL RAINFALL/WARM RAIN PROCESSES LIKELY AND HAVE
SWITCHED OVER TO THE TROPICAL Z/R RAINFALL RATE ALGORITHM ON
KCXX/KTYX RADARS.

WARM OUTFLOW FROM KATRINA AND UPPER LOW SOUTH OF JAMES BAY
INCREASING THE JET CORE WHICH WILL INCREASE THE DIVERGENCE AND
FRONTOGENESIS OVER NORTHERN SECTIONS BY 12Z WED.

...HEAVY RAINFALL...
BEST FORCING FOR HEAVY PRECIPITATION CENTERS ON 09- 15Z FOR THE
HEAVIEST RAINFALL ACROSS THE CWA WITH BEST MOISTURE CONVERGENCE/
FRONTOGENESIS. THE FORCING REMAINS OVER NORTHERN NEW YORK (KMSS)
FOR THE LONGEST PERIOD OF TIME BASICALLY 08Z WED -01Z THU.
RAINFALL AMOUNTS HEAVIEST NEAR KMSS AND LIGHTEST NEAR KVSF WITH 2
TO 5 INCHES POSSIBLE NORTH AND 1 TO 3 INCHES SOUTH.

AREAS FROM BURLINGTON SOUTH AND EAST MAY GET OUT OF THE STEADY
MODERATE TO HEAVY RAIN INTO WARM SECTOR AFTER 15Z TOMORROW WITH
SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING IN THE AFTERNOON
WITH SOME THREAT OF SEVERE WEATHER PER SPC DAY TWO OUTLOOK.

...WIND...
GREATEST THREAT FOR STRONG WINDS WOULD BE DURING MIDDAY/AFTERNOON WED WITH
POSSIBLE BOUNDARY LAYER MIXING IN WARM SECTOR. GFS SHOWING UP TO
50 KTS AT 850 MB TOMORROW AND SOME POTENTIAL FOR G35-40KTS FROM
KSLK/KBTV EASTWARD ESPECIALLY IN THE HIGHER TERRAIN. MIDNIGHT
SHIFT WILL HAVE TO EVALUATE THIS FURTHER.

&&

.HYDROLOGY...
LOOKS LIKE THE GREATEST THREAT OF EXCEEDING FLOOD STAGES WILL BE
ON THE FASTER RESPONDING SMALLER RIVERS AND STREAMS. LATEST
FORECASTS INDICATE THAT THE AUSABLE MAY APPROACH FLOOD STAGE LATE
TOMORROW AFTERNOON IF OVER 4 INCHES OF RAIN FALLS IN THE BASIN.
OTHER SMALL STREAMS AND RIVERS IN NORTHWEST VERMONT AND NORTHERN
NEW YORK WOULD BE THE MOST PRONE TO ANY FLOODING ALONG WITH
LOCAL POOR DRAINAGE AREAS AND URBAN AREAS.

&&

.PREVIOUS DISCUSSION...
(ISSUED 401 PM EDT TUE AUG 30 2005)

SYNOPSIS...
THE LONG ANTICIPATED REMNANTS OF KATRINA ARE HEADED TO OUR FA.
GFS/TPC/HPC TRACKS HAVE BEEN VRY SMLR AND CONSISTENT THE PAST 2-3
DAYS WITH GFS TRACKING KMSS-KPLB AND TPC ON CANADIAN SIDE OF ST
LWRNC VLY.

THE ACTUAL REMNANTS INTERACT WITH NRN STREAM DYNAMICS AS KATRINA
CONTS TO TRANSLATE TO XTRATROPICAL AND SFC PRS MAINTAINS OR SLIGHTLY
STRENGTHENS.

NATL DISCUSSIONS FM HPC (PMDSPD/PMDHMD AND QPFPFD) XPLAIN THE DVLPG
SITUATION ACRS FA. COUPLED UPR JET...INCRSG TROPICAL PWATS TO >2...STG
H8 35-50KTS WARM AIR AND MOISTURE ADVECTION MAKING FOR A RICH...
XTRATROPICAL CYCLONE.

ALTHOUGH GFS VRY CONSISTENT THE PAST FEW DAYS...MY QPF AND WND
FIELDS ARE FM A SLGTLY W TRACK OR COMPROMISE BTWN HPC/TPC AND GFS.

THE END RESULT WITH THIS IS:
1) SLGTLY LESS QPF VALUES FOR VT VS. MDLS AND MORE IN ST LWRNC VLY.
2) GTR PRS GRADIENT IN CHMPL VLY AND MUCH OF FA...THUS STGR WNDS AS
ALL MDLS ONLY BRG 10-20 MPH AT BEST ACRS FA YET LLVL JET EXCEEDS 40
KTS AND THUS HAVE GONE WINDY IN CHMPL VLY.
3) STORM TRACK ACRS NW NY MEANS WRM FNT LKLY LIFTING N OF MUCH OF VT
AND PSBLY SE ADRNDKS.

SHORT TERM (TONIGHT THROUGH THURSDAY)...
TNGT: SHRA ALRDY IN WRN NY WITH SCT -TSRA DVLPG IN SRN VT AND DVLPG
SHRA BTWN THIS ACTVTY IN MOHAWK VLY/CATSKILLS. THEREFORE...XPCT CONTD
DVLPG SHRA/TSRA WITH GRST THREAT ACRS ADRNDKS AND POINTS SE INTO VT.

TUE: MOST INDICATIONS THAT THE ABV MNTD ACTVTY WL SHIFT ENE WITH PSG
OF MID-LVL SUPPORT AND WE AWAIT MOISTURE RETURN FM KATRINA (WELL IN
ADVANCE) FM ACTUAL CIRCULATION. GFS WAS USED FOR THIS WITH SRN FA
LATE IN THE DAY AND THEN LIFTING N WITH TIME THRU TUES NGT/WED.

TUE/NGT/WED/WED NGT: THE RECENTLY MNTD ACTVTY INCREASES AS KATRINA
MVS FURTHER N INTO OH RVR VLY WITH INCREASING BAROCLINIC ZONE AND
WAA PTRN OF RICH...TROPICAL AIR WITH PWATS AOA 2 ADVECTING INTO
BNDRY. GFS TRACK SLIGHTLY E OF HPC...THUS WENT SLIGHT BLEND BUT
KATRINA REMNANTS LIFT NE ACRS/W ST LWRNC VLY WITH BEST OVERRUNNING
N/W OF TRACK. THUS....MAINLY ST LWRNC VLY.

THU...KATRINA HAS PUSHED THRU/N OF FA WITH ERLY CHC OF WRAPARD/CAA
INSTABILTY SHRA ALONG N FA WITH GRDL CLRG ELSEWHERE AND LESSER
DEWPOINTS AS TROPICAL AIRMASS DEPARTS WITH KATRINA.

LONG TERM (THURSDAY NIGHT THROUGH TUESDAY)...
ENSEMBLES DATA IN GOOD AGREEMENT WITH UPCOMING SYNOPTIC PATTERN ACRS
NE CONUS FOR FRIDAY THRU TUESDAY. WL CONT TO MENTION CHC POPS ACRS
MTNS AND NORTHERN ZNS ON FRIDAY ASSOCIATED WITH 5H VORT AND WEAK
ULVL FORCING. GIVEN...EXPECTED COOL TEMPS ALOFT AND SOME SURFACE
HEATING ON SATURDAY AND STEEP LOW LVL LAPSE RATES...WL MENTION CHC
POPS IN MTN ZNS. OTHERWISE...PROGGED 85H TEMPS BTWN 8-10 SUPPORT
HIGHS IN THE M/U 60S MTNS TO L70S IN THE VALLEYS FOR SATURDAY THRU
MONDAY. SFC RIDGE AND ASSOCIATED ULVL RIDGE WL SHIFT EAST INTO NEW
ENGLAND BY TUES AND LLVL WAA DEVELOPS. TEMPS BY TUESDAY WL RETURN TO
NEAR NORMAL WITH DRY WX CONTINUING.

AVIATION...
FCST CONCERN FOR THE TAFS WL BE TIMING OF PRECIP ASSOCIATED WITH
REMNANTS OF KATRINA. WL USE A BLEND OF THE GFS/ETA 7H OMEGA/MOISTURE
FIELDS TO PLACE TIMING OF PRECIP INTO TAFS. I WL MENTION TEMPO BTWN
04-06Z AT MPV/BTV FOR THE ONSET OF PRECIP...THEN PREVAILING AFT 06Z
WITH TEMPOS FOR MODERATE TO HEAVY PRECIP THRU 18Z WEDS. FOR SLK/MSS
WL TEMPO THE ONSET OF PRECIP BTWN 05-07Z...THEN GO WITH PREVAILING
GROUP. UPSTREAM OBS SUPPORT RA WITH VIS AROUND 2SM AND CIGS BTWN
010-020KFT. FOR THE PREVAILING GROUP WL GO WITH 4SM -RA/RA WITH CIGS
BTWN 015-025KFT. SFC WINDS WL BE SOUTH TO SOUTHEAST AT 10 TO 20 KNTS
WITH SOME HIGHER GUSTS ON WEDS AFTN. ALSO...WIND PROFILES SUPPORT
STRONG VEERING OF LLVL WINDS AND STRONG SPEED SHEAR. WITH 85H JET OF
35 TO 40KNTS SOME LLWS WL BE POSSIBLE...ESPECIALLY ALONG THE EASTERN
SLOPES OF THE GREEN MTNS.

HYDROLOGY...
FLD GUIDANCE INDICATES 3.5 TO 6 INCHES IN A 6-12 HR PERIOD
WHICH IS PSBL WITH REMNANTS OF TROPICAL SYSTEMS SUCH AS FLOYD -
1999.

AGAIN...FCST VALUES OF 2-4 LCLLY 5 FOR NRN NY WITH 2-4 IN
NRN 1/2 OF VT THEN 1- LCLLY 3 FOR SRN VT.

HWVR...A STALLED FNTL BNDRY AND SOME PSBL TROPICAL MOISTURE
INTERACTION PRECEDING KATRINA TNGT/TUES CUD LWR THESE VALUES
AND NEED TO BE MONITORED FOR PSBL MODIFICATIONS.

AS ALWAYS...STAY TUNED FOR PSBL CHGS/LTR UPDATES.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...FLOOD WATCH FOR VTZ001>012-016>019 UNTIL 5 AM THURSDAY.
NY...FLOOD WATCH FOR NYZ026>031-034-035-087 UNTIL 5 AM THURSDAY.
&&

SHORT TERM...SISSON
HYDROLOGY...SISSON

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE BURLINGTON VT
1000 PM EDT TUE AUG 30 2005

NYZ026>031-034-035-087-VTZ001>012-016>019-310907-
CALEDONIA VT-EASTERN ADDISON VT-EASTERN CHITTENDEN VT-
EASTERN CLINTON NY-EASTERN ESSEX NY-EASTERN FRANKLIN VT-
EASTERN RUTLAND VT-ESSEX VT-GRAND ISLE VT-LAMOILLE VT-
NORTHERN FRANKLIN NY-NORTHERN ST. LAWRENCE NY-ORANGE VT-ORLEANS VT-
SOUTHEASTERN ST. LAWRENCE NY-SOUTHERN FRANKLIN NY-
SOUTHWESTERN ST. LAWRENCE NY-WASHINGTON VT-WESTERN ADDISON VT-
WESTERN CHITTENDEN VT-WESTERN CLINTON NY-WESTERN ESSEX NY-
WESTERN FRANKLIN VT-WESTERN RUTLAND VT-WINDSOR VT-
INCLUDING THE CITIES OF...BARRE...BETHEL...BRANDON...BURLINGTON...
CANAAN...CANTON...DANBY...ESSEX JUNCTION...FAIR HAVEN...MALONE...
MASSENA...MIDDLEBURY...MONTPELIER...MORRISVILLE...NEWCOMB...
NEWPORT...OGDENSBURG...PLATTSBURGH...POTSDAM...RANDOLPH...RUTLAND...
SARANAC LAKE...SOUTH BURLINGTON...SPRINGFIELD...ST. ALBANS...
ST. JOHNSBURY...SWANTON...VERGENNES...WHITE RIVER JUNCTION...
WILLSBORO AND WINOOSKI
1000 PM EDT TUE AUG 30 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN NEW YORK AS WELL AS
CENTRAL AND NORTHERN VERMONT.

...A FLOOD WATCH IN EFFECT FROM 11 PM EDT TONIGHT THROUGH 5 AM EDT
THURSDAY..

.DAY ONE...TONIGHT THROUGH WEDNESDAY:

THE REMNANTS OF HURRICANE KATRINA LOCATED NEAR CINCINNATI OHIO WILL
TRACK NORTHEAST INTO WESTERN NEW YORK BY EARLY WEDNESDAY MORNING AND
INTO NORTHERN NEW YORK BY WEDNESDAY EVENING. WIDESPREAD MODERATE TO
HEAVY RAIN WILL DEVELOP FROM SOUTH TO NORTH ACROSS VERMONT AND
NORTHERN NEW YORK OVERNIGHT.

RAINFALL AMOUNTS THROUGH WEDNESDAY EVENING ARE EXPECTED TO AVERAGE
BETWEEN 2 AND 5 INCHES ACROSS NORTHERN NEW YORK AND EXTREME
NORTHWESTERN VERMONT...2 TO LOCALLY 4 INCHES ACROSS THE REMAINDER OF
CENTRAL AND NORTHERN VERMONT...AND ONE TO LOCALLY 3 INCHES ACROSS
SOUTHERN VERMONT...WHERE LOCALLY STRONG THUNDERSTORMS MAY OCCUR.

THE PRIMARY THREAT WILL BE FOR MINOR SMALL STREAMS AND TRIBUTARIES
FLOODING...ALONG WITH LOCALIZED URBAN AND POOR DRAINAGE
AREA FLOODING. THE GREATEST POTENTIAL FOR MINOR RIVER FLOODING WILL
BE ALONG THE AUSABLE RIVER IN NORTHERN NEW YORK BY LATE WEDNESDAY
AFTERNOON.

IN ADDITION...SOUTH WINDS OF 25 TO 35 MPH WITH GUSTS UP TO 45 MPH
WILL BE POSSIBLE ACROSS THE HIGHER TERRAIN OF VERMONT AND NORTHERN
NEW YORK AS WELL AS THE CHAMPLAIN VALLEY BY MIDDAY WEDNESDAY.

FINALLY...SCATTERED STRONG THUNDERSTORMS MAY DEVELOP ACROSS THE
SOUTHERN CHAMPLAIN VALLEY AND PORTIONS OF CENTRAL AND SOUTHERN
VERMONT ON WEDNESDAY AFTERNOON. THE GREATEST SEVERE WEATHER THREAT
WOULD BE STRONG AND DAMAGE WINDS...ALONG WITH FREQUENT CLOUD TO
GROUND LIGHTNING.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH MONDAY:

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER CALL TO ACTION STATEMENT...

RAINFALL AMOUNTS AND ANY REPORTS OF FLOODING/SEVERE WEATHER WILL BE
GREATLY APPRECIATED BY THE NATIONAL WEATHER SERVICE IN BURLINGTON.

STAY TUNED TO NOAA WEATHER RADIO ALL HAZARDS OR YOUR LOCAL MEDIA
OUTLETS FOR UPDATES.

TABER