FXUS61 KALY 082201
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
501 PM EST TUE DEC 8 2009
.SYNOPSIS...
HIGH PRESSURE WILL SLIDE INTO THE MARITIMES TONIGHT. ONE STORM
WILL RIDE ACROSS MICHIGAN AS A SECOND STORM GETS GOING OVER THE
MID ATLANTIC. THE COMBINATION OF THESE TWO STORMS WILL SPREAD A
VARIETY OF WINTER WEATHER INTO THE REGION FOR WEDNESDAY. AS THE
LOW PRESSURE SYSTEM TRACKS INTO CANADA ON THURSDAY A BRISK FLOW OF
COLDER AIR WILL FOLLOW IN ITS WAKE.
&&
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
CLOUDS INCREASE AHEAD OF MAJOR STORM SYSTEM TONIGHT. AS FOR LOW
TEMPS WENT WITH A MAV/MET BLEND.
&&
.SHORT TERM /MIDNIGHT TONIGHT THROUGH THURSDAY NIGHT/...
...SIGNIFICANT WINTER STORM TO AFFECT REGION ON WEDNESDAY...
THE FOLLOWING WARNINGS AND ADVISORIES HAVE BEEN ISSUED...
WINTER STORM WARNING FOR THE ADIRONDACKS AND SOUTHERN VERMONT.
WINTER WEATHER ADVISORIES FOR ENTIRE ALBANY FORECAST AREA EXCEPT
SOUTHEAST LITCHFIELD COUNTY.
WIND ADVISORY FOR SOUTHERN VERMONT...BERKSHIRE COUNTY...AND
TACONICS.
FLOOD WATCH FOR ULSTER...DUTCHESS...LITCHFIELD COUNTIES.
REGARDING WINTER STORM...A COMPLEX WEATHER SITUATION SETTING UP
THIS AFTERNOON. ONE STORM WILL TRACK OVER MICHIGAN AS SECOND GETS
GOING OVER MID ATLANTIC. AS SECONDARY LOW GETS GOING...STRONG
SOUTHEAST FLOW WILL PROVIDE ATLANTIC INFLOW INTO THE REGION. GEFS
ENSEMBLES SHOWS EASTERLY WINDS 4 TO 5 STANDARD DEVIATIONS ABOVE
NORMAL TRANSLATING ACROSS REGION MAINLY WEDNESDAY MORNING.
850-700MB FGEN FORCING ALSO IN PLAY AT THIS TIME AS WELL. SYSTEM
WILL BE MOVING FAST SO ALTHOUGH DYNAMICS/THERMODYNAMICS ARE
POTENT...PRECIP WILL BE MAINLY A 12 HOUR EVENT. STILL EVEN WITH
THAT...QPF ACROSS ENTIRE CWA WILL EXCEED 1 INCH AND COULD
APPROACH 2 INCHES IN ISOLATED LOCALES IN HIGHER ELEVATIONS OF
CATSKILLS AND GREEN MOUNTAINS.
CHALLENGE FOR THIS EVENT WILL BE TO DECIDE ON TRANSITION BETWEEN
RAIN AND SNOW. NAM IS COLDER OF MODELS AND WOULD ARGUE FOR AN ALL
SNOW SCENARIO FROM CAP DISTRICT NORTH. ON THE OTHER HAND GFS IS
WARMER AND THAT WOULD SPELL A QUICKER TRANSITION FROM SNOW TO
RAIN. AT THIS POINT...MAIN PRECIPITATION TYPES LOOK TO BE SNOW AND
RAIN WITH FREEZING RAIN POSSIBLE IN TRANSITION BETWEEN THE
TWO...AS SURFACE TEMPS LOOK TO RISE IN ACCORD IN WARMER AIR COMING
IN ALOFT. WILL NEED TO WATCH THIS THOUGH AS MODELS DEPICT VERY
STRONG NORTHERLY AGEOSTROPHIC FLOW.
SO WITH THESE THOUGHTS IN MIND...EXPECT SNOWFALL TOTALS OF 5-10
INCHES IN WARNING AREA...4-8 INCHES IN HIGHER ELEVATION ADVISORY
AREA...AND 3-6 INCHES IN LOWER ELEVATION ADVISORY AREA. ICE TOTALS
SHOULD HOLD BELOW 0.2 INCH. BANKING ON 12 HOUR SNOWFALL WARNING
CRITERIA OF 7 INCHES.
WITH UNCERTAINTY OVER P-TYPE...FORECASTER CONFIDENCE WITH THIS
EVENT HAS TO BE PEGGED AS MODERATE AT BEST.
NEXT CONCERN WILL BE FOR WINDS IN FAVORED DOWNSLOPE REGION OF
SOUTHERN VERMONT...BERKSHIRE COUNTY...AND ADJACENT TACONICS. NAM
30AGL WINDS REACH TO NEAR 60 KNOTS ACROSS BERKSHIRE COUNTY AT 18Z
WEDNESDAY. AT THIS POINT HAVE OPTED FOR A WIND ADVISORY...BUT WILL
NEED TO BE WATCHED FOR POSSIBLE UPGRADE TO HIGH WIND WARNING.
AS STORM PULLS INTO THE MARITIMES AND HIGH PRESSURE BUILDS
EASTWARD FROM THE SOUTHERN PLAINS STRONG WESTERLY WINDS WILL
OVERSPREAD THE REGION THURSDAY AND FRIDAY. SOME GUSTS COULD
APPROACH OR EXCEED ADVISORY LEVELS. WILL NEED TO MONITOR AS WEEK
GOES ON.
OTHER CONCERN WILL BE POTENTIAL FOR VERY HEAVY LAKE EFFECT SNOW.
LAKE EFFECT WILL BEGIN ON THURSDAY AND CONTINUE INTO THE EXTENDED
PERIOD. THIS ISSUE IS ADDRESSED IN THE EXTENDED DISCUSSION.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
LAKE EFFECT WILL BE ONGOING AT THE START OF THE EXTENDED PERIOD
ACROSS THE WESTERN DACKS AS BOTH THE 12 UTC NAM/GFS SHOW A 270
DEGREE MEAN WIND IN THE 0-3 KM AGL LAYER. ALONG WITH 850 HPA TEMPS
OF -16 TO -18 DEGREES C...AND LAKE TEMPS REMAINING ABOVE 5 DEGREES
C....MODERATE TO EXTREME INSTABILITY ON THE NIZIOL LAKE EFFECT SCALE
SHOULD ALLOW FOR A FAIRLY INTENSE SINGLE BAND OF LAKE EFFECT SNOW.
HAVE CONTINUED WITH LIKELY POPS FOR FRIDAY INTO FRIDAY NIGHT FOR
MUCH OF NORTHERN HERKIMER AND WESTERN HAMILTON COUNTIES...ALTHOUGH
IT/S YET TO BE SEEN JUST HOW FAR THE HIGHEST ACCUMULATING SNOW CAN
PROPAGATE INLAND. AS THE UPPER LEVEL AND ASSOCIATED SFC LOW CONTINUE
TO MOVE EASTWARD ACROSS CANADA ON FRIDAY...WE LOSE THE BEST FLOW FOR
A MULTI-LAKE CONNECTION...WHICH SIGNIFICANTLY DECREASES THE CHC FOR
FAR INLAND PROPAGATION...BASED ON CURRENT ONGOING CSTAR RESEARCH.
ELSEWHERE ACROSS THE CWA...SOME LAKE EFFECT FLURRIES MAY MAKE THEIR
WAY TOWARDS THE CAPITAL...SARATOGA...OR LAKE GEORGE REGIONS...SO
WILL KEEP LOW CHC/SLIGHT CHC POPS FOR THESE AREAS. THE WESTERLY FLOW
MAY ALSO UPSLOPE THE BERKSHIRES/GREENS...SO SOME LIGHT SNOW WILL BE
POSSIBLE IN THOSE AREAS AS WELL. WITH THE VERY COLD AIR ALOFT /ABOUT
1-3 STD BELOW NORMAL BASED ON THE 12 UTC GEFS/...MAX TEMPS WILL BE
HELD BELOW FREEZING IN MANY AREAS.
IT WILL REMAIN COLD THROUGH THE WEEKEND AS THE UPPER LEVEL COLD AIR
SLOWLY MODERATES...WITH LOW TEMPS IN THE SINGLE DIGITS TO TEENS AND
HIGHS IN THE 20S TO LOWER 30S. THE MODELS CONTINUE TO SHOW A
SOUTHERN STREAM SYSTEM REMAINING TO OUR SOUTH SAT NIGHT INTO
SUNDAY...ALTHOUGH WILL KEEP CHC POPS IN THE FORECAST FOR SUNDAY...AS
SOME MOISTURE IN THE FORM OF SNOW MAY MAKE ITS WAY THIS FAR NORTH ON
SUNDAY...ESP IF THE MODELS TREND NORTHWARD AT ALL. IN ADDITION...AN
ARCTIC BOUNDARY WITH ANOTHER REINFORCING SHOT OF COLD AIR WILL
APPROACH FOR LATE SUNDAY...BRINGING A CHC FOR SNOW SHOWERS AND
SQUALLS WITH THE SFC FRONT.
BEHIND THIS SYSTEM...IT WILL REMAIN RATHER COLD TO START THE
UPCOMING WORK WEEK...WITH THE -14 TO -18 DEGREE AIR RETURNING AT 850
HPA. THE LATEST OPERATIONAL 12 UTC GFS SHOWS A POTENT STORM MOVING
UP THE EASTERN SEABOARD ON LATE TUESDAY INTO NEXT WED. ALTHOUGH MANY
OF THE ENSEMBLE MEMBERS DO HAVE A STORM SOMEWHERE...THERE IS
CONSIDERABLE SPREAD REGARDING THIS SYSTEM /AS WOULD BE EXPECTED
SINCE IT/S SO FAR OUT/...AND THE OPERATIONAL SEEMS THE MOST EXTREME
WITH IT/S SOLUTION FOR QPF AND STORM INTENSITY. WILL ADD LOW CHC
POPS TO FORECAST FOR TUES NIGHT FOR NOW AND WILL CONTINUE TO MONITOR.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
THE PERIOD WILL START WITH VFR FLIGHT CONDITIONS AND LOW CLOUDS
SLOWLY DISSIPATING AS HIGH CLOUDS BEGIN MOVING IN. VFR CLOUDS WILL
CONTINUE TO INCREASE THROUGH THE EVENING HOURS. MVFR CIGS WILL BE
FIRMLY IN PLACE AT KPOU/04Z...KALB/05Z AND KGFL/06Z. PRECIPITATION
FROM THE SYSTEM CURRENTLY IN THE PLAINS WILL COME IN THE FORM OF
SNOW STARTING AT KPOU AT 07Z...MOVING SOUTH TO NORTH REACHING KALB
AT 08Z AND KGFL AT 09Z. SNOW WILL CONTINUE...BECOMING MORE INTENSE
AND DETERIORATING VSBYS TO VLIFR WEDNESDAY MORNING.
IN THE VALLEYS...SNOW WILL START TO MIX WITH RAIN AROUND
14Z/KPOU...15Z/KALB AND 16Z/KGFL AS SOUTHERLY FLOW BRINGS WARMER AIR
IN ALOFT. THIS FLOW WILL CONTINUE TO TRANSITION SNOW/RAIN MIX TO
PERIODS OF RAIN IN THE AFTERNOON FOR ALL TERMINALS. DURING THE
RAIN/SNOW MIX...VSBYS WILL IMPROVE TO IFR WITH IFR CIGS OVER THE
REGION.
WINDS WILL CONTINUE FROM THE SOUTH TO SOUTHWEST THIS AFTERNOON...
SHIFTING OVERNIGHT TO THE EAST AND SOUTHEAST. WIND SPEEDS WILL
INCREASE 5-10KTS AFTER SUNRISE AND CONTINUE TO INCREASE 10-15KTS
THROUGHOUT THE DAY.
OUTLOOK...
WED...MVFR/IFR...SN/RA LIKELY.
THUR...VFR/MVFR...CHC -SHSN. WINDY.
FRI-SAT...VFR. NO SIG WX.
SUN...VFR...SLGT CHC -SHSN.
&&
.HYDROLOGY...
NO HYDRO PROBLEMS EXPECTED THROUGH EARLY WEDNESDAY AS ANY
PRECIPITATION UP TO THAT TIME WILL COME IN THE FORM OF SNOW AND THUS
HAVE NO DIRECT IMPACT ON THE RIVERS.
ON WEDNESDAY...SNOW WILL CHANGE TO RAIN ACROSS MUCH OF THE AREA
FROM CAPITAL DISTRICT SOUTH. GIVEN EXPECTED HIGH PRECIPITATION
RATES AND TRANSITION FROM RAINFALL TO SNOWFALL WEDNESDAY
MORNING...FEEL THAT A FLOOD WATCH IS PRUDENT FOR OUR SOUTHERN TIER
OF COUNTIES...DUTCHESS...ULSTER...LITCHFIELD...WHERE MORE OF
PRECIPITATION WILL BE RAIN. WE ARE MAINLY EXPECTING URBAN AND SMALL
STREAM FLOODING POTENTIAL PRIMARILY IN THE PERIOD FROM 6 AM TO
NOON.
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...FLOOD WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING
FOR CTZ001-013.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST
WEDNESDAY FOR CTZ001.
NY...FLOOD WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING
FOR NYZ063>066.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST
WEDNESDAY FOR NYZ032-038>041-043-047>054-058>061-063>066-
083-084.
WIND ADVISORY FROM 4 AM TO 4 PM EST WEDNESDAY FOR NYZ054-061.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 7 PM EST
WEDNESDAY FOR NYZ033-042-082.
MA...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST
WEDNESDAY FOR MAZ001-025.
WIND ADVISORY FROM 4 AM TO 4 PM EST WEDNESDAY FOR MAZ001-025.
VT...WIND ADVISORY FROM 4 AM TO 4 PM EST WEDNESDAY FOR VTZ013-014.
WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 7 PM EST
WEDNESDAY FOR VTZ013>015.
&&
$$
SYNOPSIS...OKEEFE
NEAR TERM...OKEEFE/BGM/IAA
SHORT TERM...OKEEFE
LONG TERM...FRUGIS
AVIATION...KGS
HYDROLOGY...RCK
