000
FXUS61 KALY 240845
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
345 AM EST TUE NOV 24 2009

.SYNOPSIS...
WEAK HIGH PRESSURE WILL BUILD IN FROM EASTERN CANADA 
TODAY...POSSIBLY BRINGING SOME BREAKS OF SUNSHINE FOR THE AFTERNOON. 
THIS HIGH PRESSURE WILL HOLD INTO WEDNESDAY BEFORE DRIFTING OFFSHORE 
BY THANKSGIVING. A FEW DISTURBANCES WILL SPREAD SOME CLOUDS OUR WAY 
WITH ONLY MINIMAL CHANCES OF RAIN SHOWERS.  

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 330 AM...RADARS STILL INDICATED SCATTERED LIGHT 
SHOWERS...MAINLY EAST OF THE HUDSON VALLEY. MORE THAN 
LIKELY...PATCHY DRIZZLE OUT THERE WHICH IS HARD TO DETECT ON RADAR. 
THE MAIN DISTURBANCE STAYED WELL TO OUR SOUTH AND EAST BUT A PRETTY 
GOOD ONSHORE FLOW SATURATED THE LOWER LEVELS OF THE COLUMN. 
NOW...THE CHALLENGE IS TO FORECAST WHEN ANY AND ALL PRECIPITATION 
ENDS AND IF THE CLOUDS WILL BREAK UP.

THE LATTER IS NO EASY TASK SINCE ONCE AGAIN...ANY MIXING WILL BE 
MITIGATED BY THE MERE FACT THAT WE ARE DEALING WITH NO MORE THAN A 
23 DEGREE SUN ANGLE. ALSO...MODEL SOUNDINGS INDICATE A PRETTY 
IMPRESSIVE SHALLOW INVERSION THAT WOULD HAVE BE WORKED OUT BEFORE 
MIXING WOULD SCOUR THE CLOUDS.

WE FELL ANY SHOWER/DRIZZLE ACTIVITY SHOULD BE OVER BY AFTERNOON IN 
ALL AREAS. 

WE WILL FOLLOW THE CANADIAN ASTRONOMICAL FORECAST AND FORECAST SOME 
"BREAKS" BY AFTERNOON (CLOUD COVER INTO THE HIGH END OF THE 
SCATTERED RANGE). THE CANADIAN ASTRONOMICAL FORECAST ACTUALLY LOOKS 
SLIGHTLY OPTIMISTIC TO US BUT IT HAS HAD A PRETTY GOOD TRACK RECORD 
IN OUR OPINION. BREAKS OR NOT...MODEL SOUNDINGS FROM BOTH THE NAM 
AND GFS INDICATE THAT OUR HIGH TEMPERATURES WILL LIKELY FALL A 
LITTLE SHORT OF BOTH THE NAM AND MAV MOS NUMBERS...DESPITE STARTING 
OUT ON THE MILD SIDE. WE FIGURE HIGH TEMPERATURES WILL TOP OUT 
WITHIN A FEW DEGREES OF 50S REGION WIDE...PERHAPS MID 50S IN THE MID 
HUDSON VALLEY.    

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
OUR CLOUD CHALLENGE HARDLY ENDS AFTER TODAY. TONIGHT...THE BIG 
QUESTION WILL BE WHETHER CLOUDS REFORM UNDERNEATH MOISTURE TRAPPED 
UNDERNEATH THE INVERSION OR NOT. AT THE SURFACE...WEAK HIGH PRESSURE 
WILL BUILD DOWN FROM CANADA. THE KEY IS THAT THE HIGH IS INDEED 
WEAK...AND DEVELOPS UNDERNEATH A RIDGE ALOFT. THIS SETUP FAVORS A 
PRETTY GOOD INVERSION WHICH WOULD FAVOR THE REFORMATION OF STRATUS 
CLOUDS...AT LEAST IN VALLEY AREAS. IF THE SKY WERE TO REMAIN 
CLEAR...FOG WOULD LIKELY FORM.

SIGNALS ARE CROSSED WHETHER THE FOG OR STRATUS CLOUDS WOULD 
DOMINATE. SINCE THE JURY IS STILL OUT...WE WILL PLAY IT IN THE 
MIDDLE...GOING WITH PARTLY CLOUD CONDITIONS...EXCEPT MORE CLOUDS IN 
THE ESPECIALLY THE HUDSON VALLEY. WILL MENTION PATCHY DENSE FOG FOR 
NOW. DEWPOINTS UPSTREAM ARE NOT ALL THAT LOW (IN THE 30S) SO WE DO 
NOT LOOK FOR TEMPERATURES TO FALL BELOW NORMAL...BUT CERTAINLY 
COOLER THAN THIS OVERNIGHT WAS. LOOK FOR LOW TEMPS GENERALLY IN THE 
30S...EXCEPT UPPER 20S IN SOME SHELTERED MOUNTAIN VALLEYS IN THE 
DACKS.

WEDNESDAY...THE BIG TRAVEL DAY BEFORE THANKSGIVING...STILL LOOKS 
MAINLY DRY ACROSS OUR REGION. AFTER STARTING OUT WITH SOME PATCHY 
DENSE FOG AND/OR LOW CLOUDS...SOME FILTERED SUNSHINE IS POSSIBLE 
BEFORE MORE HIGH CLOUDS MOVE IN FROM THE WEST. THERE IS A SHORT WAVE 
FORECAST TO LIFT SOUTHWEST TO NORTHEAST ACROSS OUR REGION. 
HOWEVER...INTEGRATED MOISTURE IN THE COLUMN WILL BE LIMITED (ONCE 
YOU GET MUCH OFF THE DECK) WITH VERY LITTLE IF ANY ISENTROPIC LIFT. 
WE WILL CONTINUE THE SLIGHT CHANCE OF SHOWERS WEST OF THE HUDSON 
VALLEY OVER THE ELEVATED TERRAIN...BUT ANY ISOLATED SHOWERS IN THESE 
AREAS WOULD BE LIGHT AND SHOULD HAVE ALMOST NO IMPACT ON TRAVEL. 

MIXING LOOKS SLIGHTLY BETTER ON WEDNESDAY...BUT STILL LIMITED...AND 
NO WHERE NEAR THE TYPICAL H850...OR EVEN H925MB FOR THAT MATTER. 
THIS WOULD TRANSLATE TO SURFACE TEMPERATURES A COUPLE POINTS HIGHER 
THAN TODAY...GENERALLY IN THE 50-55 RANGE...EXCEPT 45-50 RANGE 
ACROSS THE HIGHER TERRAINS. NEVERTHELESS...THESE VALUES ARE A GOOD 
5-7 DEGREES OVER NORMAL HIGHS. 

"QUITE" WEATHER WILL CONTINUE WEDNESDAY NIGHT ALTHOUGH BY THIS 
TIME...A SURFACE RIDGE OVER THE NORTHEAST WILL BEGIN TO BREAK 
DOWN. CLOUDS...FROM AN EVOLVING UPPER AIR LOW WELL UPSTREAM...WILL 
TEND TO INCREASE. TEMPERATURES OVERNIGHT WILL LIKELY BE ABOUT 5 DEGS 
MILDER THAN TUESDAY NIGHT...GENERALLY IN THE 35-40 RANGE...WITH SOME 
COLDER READINGS IN OUTLYING REGIONS.

THANKSGIVING WILL SEE THE AFOREMENTIONED UPPER AIR LOW/TROUGH 
BEGINNING TO MOVE TOWARDS US FROM THE OHIO VALLEY...BUT AT A SNAILS 
PACE. ALL THE GUIDANCE WE HAVE PERUSED WOULD INDICATE NOTHING MORE 
THAN A FEW SCATTERED LIGHT SHOWERS OR POCKETS OF DRIZZLE WITH AN 
OTHERWISE DRY DAY. THERE COULD EVEN BE A FEW BREAKS OF MIDDAY 
SUNSHINE BUT CLOUDS LOOK TO INCREASE DURING THE AFTERNOON. EVEN 
SO...HIGH TEMPERATURES LOOKS VERY SIMILAR TO WEDNESDAY. MORE ABOUT 
THE EVOLVING UPPER AIR LOW WILL FOLLOW IN THE EXTENDED.            
        

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...

...CONSIDERABLE UNCERTAINTY REMAINS WITH DEVELOPING NOR-EASTER...

UNLIKE THIS TIME YESTERDAY...THE GFS AND ASSOCIATED INTERNATIONAL 
GLOBAL MODELS HAVE DIVERGED ONCE AGAIN.  THE GFS AND RELATED 
ENSEMBLE DATA ARE IN A CLOSE CLUSTER WITH LOW STANDARD DEVIATIONS 
ALOFT AND AT THE SURFACE WHICH FAVORS AN IMPRESSIVE NOR-EASTER FOR 
THE REGION.  HOWEVER...THE GGEM/ECMWF AND EVEN THE 18Z/23 DGEX POINT 
TOWARD A FURTHER OFFSHORE SURFACE CYCLONE WITH THE MAIN IMPACT FOR 
THE REGION FROM THE UPPER LOW.  BASED ON CLOSE COLLABORATION WITH 
NEIGHBORING OFFICES AND HPC...WE WILL FAVOR THE 00Z ECMWF AT THE 
SURFACE AND BLEND THE 500MB FIELDS WHICH POINTS US TOWARD ANOTHER 
SCENARIO.  BASED ON CSTAR RESEARCH OF COOL SEASON CUTOFF UPPER 
LOWS...WE WILL HAVE TO MONITOR THE HIGHER TERRAIN AS THESE SYSTEMS 
CAN PRODUCE A BIT MORE QPF WHICH SEEMS TO MAXIMIZE DURING THIS 
MONTH. 

WITH THE FURTHER OFFSHORE SURFACE WAVE...UPPER LOW SHOULD BECOME THE 
MORE DOMINANT PLAYER HEADING INTO FRIDAY AND HAVE ADJUST POPS 
DOWNWARD INTO THE LIKELY RANGE TO AVOID A LARGE SWING FROM THE 
PREVIOUS FORECAST.  BASED ON THE AFOREMENTIONED CSTAR 
RESEARCH...WILL GO TOWARD THE HIGHER END OF LIKELY WITH REGARD TO 
POPS AND RAISE THE QPF ROUGHLY A TENTH OF AN INCH PER 1K FEET.  THE 
QUESTION NEXT BECOMES THE THERMAL PROFILE AS COLD ADVECTION IS 
EXPECTED TO PURSUE THROUGH THE DAY.  THIS IS EXPECTED TO BE AN 
ELEVATION DEPENDENT RAIN/SNOW LINE AS WE HAVE ATTEMPTED TO REFLECT 
THIS NOTION IN THE GRIDS/FORECAST THROUGH FRIDAY.  EVENTUALLY...THE 
COLDER AIR WILL PENETRATE THE ENTIRE COLUMN FRIDAY NIGHT WITH MOST 
PRECIP IN THE FROZEN VARIETY.  WE WILL CONTINUE TO MONITOR THE 
POTENTIAL FOR A DEFORMATION AXIS AS THE UPPER LOW SLOWLY LIFTS 
NORTHEAST OVERNIGHT.

THE NEXT CONCERN WILL BE WINDS FRIDAY NIGHT INTO SATURDAY AS 30-50KT 
WINDS AT 925MB AND 850MB RESPECTFULLY ARE EXPECTED WITH TIGHT 
SURFACE PRESSURE GRADIENT AS DEEP SURFACE LOW OVER THE CANADIAN 
MARITIMES.  COINCIDING WITH THE COLD ADVECTION THIS MAY JUSTIFY THE 
POTENTIAL FOR ADDITIONAL HEADLINES WITH RESPECT TO THE WIND.  

THESE HAZARDS WILL BE ADDRESSED IN THE HWO THIS MORNING.

QUIETER WEATHER EXPECTED FOR THE SECOND HALF OF THE WEEKEND AS 
SUBSIDENCE UNFOLDS WITH ASSOCIATED HEIGHT AND SURFACE PRESSURE 
RISES.  A LIGHT OVERRUNNING EVENT...PER THE ECMWF...MAY BRING A 
LIGHT WINTRY MIX TO THE REGION OVERNIGHT SUNDAY INTO MONDAY.  
CONFIDENCE IN THIS SCENARIO IS QUITE LOW AND WILL ONLY PLACE 20 POPS 
AT THIS TIME.

TEMPERATURES THROUGH THE PERIOD WERE A BLEND OF HPC AND ECMWF.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
UPPER LEVEL TROUGH AXIS CONTINUES TO SLOWLY ADVANCE NORTHEAST.  THIS 
FEATURE IS ASSOCIATED WITH MVFR CIG AND BORDERING IFR WITH LIGHT 
RAIN SHOWERS AND/OR DRIZZLE.  EXPECT THESE CIGS TO OVERSPREAD THE 
TAF SITES THROUGH THE REMAINDER OF THIS MORNING.  AS THIS TROUGH 
LIFTS NORTHEAST AND WEAKENS...SOME IMPROVEMENTS ARE EXPECTED WITH A 
DECREASE IN PRECIPITATION COVERAGE AND SLOWLY RISING CIGS.  COULD 
SEE VFR CONDITIONS LATE TODAY WHICH MAY RESULT IN ISSUES AFTER 
SUNSET. 

SURFACE RIDGE AXIS IS EXPECTED TO BE OVER THE REGION RESULTING IN 
LIGHT WINDS AND PARTIALLY CLEAR CONDITIONS.  WITH EXPECTED AMPLE LOW 
LEVEL MOISTURE...WE COULD BE SETTING THE STAGE FOR FOG.  WE WILL 
TREND TAFS INTO THIS DIRECTION AND MONITOR TRENDS/FORECAST 
SOUNDINGS.  
   
OUTLOOK... 
TUE OVNGT...VFR...CHANCE FOR IFR WITH FOG.
WED...VFR/MVFR...CIGS.  NO SIGN WX EXPECTED AT THIS TIME.
WED NT...MVFR...CHC IFR FOR FOG/DZ.
THANKSGIVING DAY...VFR/MVFR...CIG...NO SIG WX EXPECTED AT THIS TIME. 
THU NGT-FRI...VFR TO MVFR/IFR...RAIN LIKELY. CHC LLWS.
FRI NGT-SAT...MVFR/IFR...CHC -RA CHANGING TO -RASN. CHC LLWS.

&&

.HYDROLOGY...
NO HYDRO PROBLEMS THROUGH THANKSGIVING DAY.

VERY LITTLE RAIN FELL WITH THE LAST SYSTEM AND HAD NO AFFECT ON 
RIVERS AND STREAMS. MAINLY DRY WEATHER EXPECTED THROUGH 
THANKSGIVING...WITH ANY LIGHT SHOWERS BRINGING WELL UNDER A TENTH OF 
AN INCH AND HAVING NO BEARING ON WATERSHEDS THROUGH THE HYDROLOGICAL 
SERVICE AREA. 

THE NEXT CHANCE OF WIDESPREAD PRECIPITATION WILL BE FROM LATE 
THURSDAY NIGHT INTO THE WEEKEND...AS A POTENTIALLY STRONG STORM MAY 
IMPACT THE REGION. SIGNIFICANT PRECIPITATION IS POSSIBLE BUT PRECIP 
AMOUNTS AND TYPE CONTINUE TO BE HIGHLY UNCERTAIN AT THIS TIME.

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...HWJIV
NEAR TERM...HWJIV
SHORT TERM...HWJIV
LONG TERM...BGM
AVIATION...BGM
HYDROLOGY...HWJIV