000
FXUS61 KALY 172359
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
759 PM EDT TUE JUL 17 2012
.SYNOPSIS…
A HOT AND HUMID AIR MASS WILL LINGER ACROSS THE REGION TODAY. A COLD
FRONT WILL SAG SLOWLY SOUTH FROM THE SAINT LAWRENCE VALLEY THIS
EVENING…REACHING THE MOHAWK VALLEY WEDNESDAY MORNING…AND THE
LONG ISLAND SOUND BY WEDNESDAY EVENING. HIGH PRESSURE WILL BUILD
FROM HUDSON`S VALLEY LATE WEDNESDAY INTO THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/…
AS OF 745 PM…HEAT ADVISORY HAS BEEN ALLOWED TO EXPIRE. NO OTHER
CHANGES AT THIS TIME.
AS OF 7 PM…CONTINUING TO WATCH CONVECTIVE TRENDS ACROSS PORTIONS
OF THE DACKS. LATEST MESOSCALE ANALYSIS REVEALS AN OUTFLOW BOUNDARY
ACROSS THE TUG HILL…INTO NORTHERN HERKIMER AND HAMILTON COUNTIES.
SBCAPES ARE NEAR 2000 J/KG AND 0-6KM SHEAR WAS BETWEEN 40-50KTS.
FURTHER SOUTH OF THIS CONVECTION…SBCAPES ARE A BIT HIGHER BUT SO
ARE THE MID LEVEL TEMPS WITH 700MB TEMPS AT +10C TO +12C PER SPC/RAP
HOURLY UPDATES. SO THE QUESTION REMAINS JUST HOW FAR SOUTH THIS
CONVECTION WILL MAKE IT BEFORE WE LOSE THE DAYTIME HEATING AND/OR IT
OUTRUNS THE BETTER SHEAR PROFILES. SO FOR THIS UPDATE…WE WILL
DECREASE POPS THROUGH THE EVENING. HOWEVER…THE FRONTAL BOUNDARY
CONTINUES TO SLOWLY SAG SOUTHWARD OVERNIGHT SO WE CAN NOT RULE OUT
ADDITIONAL CONVECTION OVERNIGHT. THE HRRR REFLECTIVITY FORECASTS
SUGGEST WE COULD SEE SOME ADDITIONAL CONVECTION OVERNIGHT ACROSS THE
MOHAWK VALLEY AND INTO THE CAPITAL REGION.
AS FOR TEMPERATURES…THE COMBINATION OF AN ANTICYLONIC RIDGE SEEN
IN THE H2O VAPOR AND DOWNSLOPING FROM THE SOUTHWEST WIND
TRAJECTORIES…MAY AREAS IN THE VALLEYS QUICKLY CLIMBED INTO THE MID
AND UPPER 90S WITH DEWPOINT POOLING INTO THE HUDSON RIVER VALLEY.
GIVEN A RATHER MUGGY EVENING…WE WILL HOLD ONTO THE HEAT ADVISORY
AT THIS TIME.
PREV DISC…
WMFNT AND ITS CLOUDS AND -SHRA/TSTMS HAS MOVED E OF FCA. PATCHY
MID CLOUDS ACROSS S TIER AND VT…WITH CLEARING OVER REST OF FCA.
THE CLOUDS WILL CLEAR THE S AND E PTNS OF FCA 17-18UTC.
WITH FULL SUN FOR SVRL HRS CONVECTIVE POTENTIAL EVOLVES…AND
CURRENT THINKING HAS NOT CHANGED FM EARLIER TDY. WHILE 12UTC ALB
SNDG AND MDL SOUNDINGS ACROSS FCA SHOW SOME CAPPING…BUF 12UTC
SNDG AND MDL SNDGS INDICATE THIS WILL BE GONE PARTICULARLY N HALF
OF BTWN 18-21UTC.
MOST GUID AND MDL SOUNDINGS HAVE 1000-2000 J/KG OF CAPE ACROSS FCA
AND MINIMAL CIN VALUES BY 21UTC…AGAIN PARTICULARLY N. MAIN ISSUE
AT LEAST INTO THE EVENING IS LACK OF LARGE SCALE FORCING. MID AND
UPR JET AXIS AND FAVORABLE QUADS REMAIN WELL N OF FCA…WITH ONLY
MINIMAL INTERACTION ACROSS N TIER THIS AFTN. AS THIS SHIFTS S TNGT
THE DYNAMICS WILL ALSO SHIFT S….BY NOT UNTIL AFT 03UTC.
IN SPITE OF A LACK OF LARGE SCALE DYNAMIC FORCING THERE`S DIURNAL
HEATING…AND MOST AREAS WILL SEE L/M 90S…ELEVATED TRRN…GRTLKS
LAKE BREEZES…COLD POOLS AND OUTFLOW BOUNDARIES FROM CONVECTION
TO THE N…A WEAK TROF ACROSS THE E GRTLKS…AND LOCAL EFFECTS TO
TRIGGER CONVECTION. H850 HPA JET OF 30-50KTS NOSES INTO FCA
DURING THE AFTN…AND IT COULD BE SUFFICIENT W/ EXPECTED CAPE TO
GET THINGS GOING. ADD PWATS OF 1.50-ALMOST 2.0 TODAY.
ON THE LARGER SCALE SFC LOW IN OTTAWA VALLEY WILL ZIP EAST TO
MAINE BY EVENING…AND ITS TRAILING CDFNT WILL START TO SAG INTO
N TIER OF NYS BY 00UTC…REACHING THE MHWK VLY BY WED MORNING.
MOST OF LARGE SCALE AND LOCAL MESO SCALE WRF AND HRRR MODELS HV
CONVECTION FIRING ALONG AND AHEAD OF THE CDFNT DURING THE MID AFTN
NR CANADIAN/USA BORDER…AND SHIFTING TO N TIER OF FCA 21-23UTC.
ALL THESE MODELS MAINTAIN THIS CONVECTION INTO THE EVENING AS IT
SHIFTS ESE…POSSIBLY REACHING MHWK VLY/CAP RGN. BUT MODELS WEAKEN
CONVECTION WITH THE END OF DIURNAL HEATING…AND RESURGENCE OF THE
CAP OVERNIGHT. WITH H850 JET PUNCHING EAST….0-6 KM DEEP BULK
SHEAR VALUES ARE ALREADY 40+…MHWK VLY AND N.
SPC HAS OUTLOOKED N HALF OF FCA TODAY. POTENTIAL WATCH DECISION
95% BASED ON LATEST MCD. BUT THE SOUTHERN EXTENT OF SVR CONVECTION
REMAINS QUESTIONABLE.
IN SUMMARY EXPECT A HOT HUMID AFTN. CONVECTION ORGANIZING ALONG N
NY BORDER. APPEARS CURRENT LINE ALONG NVT/N NH IS BACK BUILDING INTO
NYS…AND THIS WILL BCM MORE ORGANIZED NEXT FEW HRS AND SHIFT ESE.
HOW FAR SOUTH REMAINS A QUESTION…BUT N TIER OF FCA REMAINS AT
RISK FOR POSSIBLE SVR. ISOLD-SCT CELLS COULD STILL FORM AFTER CAPS
GIVE WAY THIS AFTN ANYWHERE FM MHWK VLY N AND THESE COULD BCM
QUITE HEALTHY…WITH HEAVY DOWNPOURS.
AS CDFNT SAGS SLOWLY S TNGT IT WILL REMAIN FOCUS OF -SHRA AND
CONVECTION…BUT MDLS CLEARLY SUG CONVECTION WEAKENS CONSIDERABLY
OVERNIGHT.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/…
AFTER A LATE NIGHT LUL IN CONVECTION MDL SUITE IN AGREEMENT WITH
CDFNT BEGINNING THE DAY IN MHWK VLY AND CONTINUING SWRD.
CONVECTION FIRES MID DAY…WITH MAIN THREAT S & E OF ALB. WITH S
AREAS IN BETTER JET DYNAMICS…JUXTAPOSED TO CDFNT AND CAPES
REBUILDING TO 1500-3000 J/KG ASSORTED GUIDANCE INDICATES THE
LIKELY LOCATIONS FOR A SVR CONVECTION THREAT WILL BE SOUTH OF
ALBANY.
VARIATIONS IN CLOUD COVER COULD DAMPEN THIS RESPONSE AND LOCAL WRF
DOESN`T GET CONVECTION WELL ORGANIZED TILL ITS STRADDLING THE
SOUTH TIER OF COUNTIES WED.
WITH PWATS STILL IN THE 1.50-2.00 INCH RANGE SOUTH SOME LOCALLY
HVY DOWNPOURS ARE POSSIBLE…AS SOME LOCATIONS COULD RECEIVE A
QUICK FEW INCHES OF RAINFALL. THE MID LEVEL FLOW IS FAST…SO ANY
CELLS SHOULD BE FAST MOVERS…AND LARGE PCPN DEFICITS CONTINUE
OVER THE HSA.
FURTHER N WED TEMPS WILL REMAIN ABV NORMALS ONE MORE DAY BUT
DRIER AIR WILL BE FILTERING INTO N TIER WITH CLEARING.
WED NT CDFNT MOVES S OF FCA…MOST OF AREA CLEARS AND DRIES..HWVR
CLOUDS MAY LINGER OVER S PTNS OF FCA. WHAT WILL BE VERY NOTICEABLE
IS DEPARTURE OF HUMIDITY AS TD DROP INTO 50S.
BY THU LARGE SFC HIGH BUILDS SE INTO FCA FM ONT/HUD BAY WITH FAIR
AND SEASONABLE CONDS ACROSS ENTIRE FCA INTO THU NT.
A RECENT WRINKLE IN NAM/GFS IS THE FORMATION OF A WAVE ALONG THE
STALLED FRONT TO OUR SOUTH LATE THU AND FRI OVER S VA. WHILE NOT
AS VIGOROUS AS THE 06UTC RUNS,..THE CURRENT SUITE BRINGS INCRG
CLOUDS AND CHC -SHRA TO S TIER OF FCA LATE FRI.
WILL POPULATE THIS PERIOD WITH MET/MAV BLEND AS GUID IN CLOSE
AGREEMENT.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/…
A NICE START TO THE WEEKEND AS A RIDGE OF HIGH PRESSURE WILL BE OVER
THE REGION ON SATURDAY. THE GFS WANTS TO LINGER ONTO THE UPPER TROF
AXIS AND RESULTS IN ISOLATED CONVECTION ACROSS THE REGION.
HOWEVER…THE GFS ALSO HINTS AT RISING HEIGHTS WHICH IS ALONG THE
SAME AS OTHER GLOBAL GUIDANCE. WE WILL RETAIN THE DRY FORECAST
ALONG WITH AT OR SLIGHTLY BELOW NORMAL TEMPERATURES.
THEN TRENDS ON SUNDAY ARE BECOMING A LITTLE MORE ACTIVE…BUT NOT A
WASHOUT. ANOTHER SHORTWAVE WITHIN THE NORTHWEST FLOW REGIME ALOFT
IS EXPECTED TO TRACK TOWARD THE GREAT LAKES REGION LATER ON SUNDAY.
AT THIS TIME…WE WILL INTRODUCE A SLIGHT CHANCE FOR CONVECTION AND
CONTINUE TO MONITOR TRENDS. BY SUNDAY NIGHT…ALL OF THE AVAILABLE
GUIDANCE SUGGESTS A PV ANOMALY CROSSES THE REGION. WE WILL HAVE THE
HIGHER POPS…30-40 PERCENT…AT THIS TIME ACROSS MOST OF THE REGION
SUNDAY NIGHT.
BY MONDAY…THAT PV ANOMALY DOES TRACK EAST YET THE CYCLONIC FLOW
REGIME REMAINS IN PLACE. THE ECMWF/DGEX WANTS TO LINGER A SURFACE
TROUGH ACROSS THE REGION WHILE THE GFS IS THE MOST AGGRESSIVE TO
CLEAR OUT OF OUR SOUTHERN COUNTIES. HPC GUIDANCE IS SOMEWHAT IN THE
MIDDLE OF THE GUIDANCE ENVELOPE AND HAVE FOLLOWED THE GUIDANCE
CLOSELY. TEMPERATURES AND DEWPOINTS WILL BE ON THE CLIMB AS WELL AS
WE AVERAGE TOWARD ABOVE NORMAL INTO EARLY NEXT WEEK.
&&
.AVIATION /23Z TUESDAY THROUGH SUNDAY/…
SHOWERS AND THUNDERSTORMS HAVE BEEN CONFINED TO FAR NORTHERN AREAS
TODAY AS A COLD FRONT DROPS SOUTH FROM CANADA. AN ISOLATED
THUNDERSTORM IS NOT OUT OF THE QUESTION FURTHER SOUTH BUT QUESTION
IS HOW FAR SOUTH DO STORMS MOVE? BEST CHANCE AT KGFL LATE THIS
EVENING BUT ENOUGH UNCERTAINTY TO LEAVE OUT OF TAF. MODELS SHOW MOST
CONVECTION DYING OUT OVERNIGHT BUT SOME ISOLATED RAIN SHOWERS AND
FOG AND STRATO CU EXPECTED AS MOISTURE POOLS AHEAD OF COLD FRONT.
FOR TOMORROW…COLD FRONT CONTINUES TO MOVE SOUTH WITH BEST CHANCE
OF SHOWERS/THUNDERSTORMS OVER SOUTHERN AREAS AS COLD FRONT CONTINUES
SOUTH BEFORE CLEARING AREA DURING EVENING.
WEST SOUTHWEST WINDS 10 TO 15 KTS THIS EVENING SUBSIDING TO 3 TO 6
KTS OVERNIGHT. FOR WEDNESDAY…WINDS WEST TO NORTHWEST BECOMING
NORTHWEST TO NORTH AT 5 TO 10 KTS.
OUTLOOK…
WED…VFR/MVFR. SCT SHOWERS/TSTMS.
THU..NO SIG WX.
FRI-SUN…VFR…SLIGHT CHC ISOLD AFTERNOON TSTM.
&&
.FIRE WEATHER…
A HOT AND HUMID AIR MASS WILL LINGER ACROSS THE REGION TODAY. A COLD
FRONT WILL SAG SLOWLY SOUTH FROM THE SAINT LAWRENCE VALLEY THIS
EVENING…REACHING THE MOHAWK VALLEY WEDNESDAY MORNING…AND THE
LONG ISLAND SOUND BY WEDNESDAY EVENING. HIGH PRESSURE WILL BUILD
FROM HUDSON`S VALLEY LATE WEDNESDAY INTO THE WEEKEND.
RELATIVE HUMIDITY VALUES WILL INCREASE TO 80 TO 100 PERCENT
TONIGHT..AND RECOVER TO 40-60 PERCENT WEDNESDAY AFTERNOON. VALES
WEDNESDAY WILL INCREASE TO 60-80 PERCENT.
SOUTHWEST WINDS 10 TO 15 MPH WITH HIGHER GUSTS WILL BECOME LIGHT
AND VARIABLE TONIGHT AT 10 MPH OR LESS…AND INCREASE FROM THE
WEST NORTHWEST TO 5 TO 15 MPH ON WEDNESDAY.
&&
.HYDROLOGY…
NO HYDRO PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS OVER THE
NEXT 5 DAYS.
SHOWERS AND THUNDERSTORMS ASSOCIATED WITH A FRONTAL PASSAGE
TONIGHT INTO WEDNESDAY WILL PRODUCE SOME HEAVY RAINFALL DUE TO A
SHORT PERIOD OF ANOMALOUSLY HIGH PRECIPITABLE WATER VALUES IN THE
1.5 TO 2 INCH RANGE. SOME PONDING OF WATER ON ROADWAYS OR POOR
DRAINAGE FLOODING IS POSSIBLE…ESPECIALLY ON WEDNESDAY. ZONAL
FLASH FLOOD GUIDANCE VALUES REMAIN HIGH FOR MID JULY. THE
POTENTIAL FOR FLASH FLOODING IS LOW AT THIS TIME IN THE ALY HYDRO
SERVICE AREA.
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…BGM/SNYDER
SHORT TERM…SNYDER
LONG TERM…BGM
AVIATION…SND
FIRE WEATHER…SNYDER
HYDROLOGY…WASULA/SNYDER
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