762 
fxus61 kaly 212322 
afdaly 


Area forecast discussion 
National Weather Service Albany New York 
722 PM EDT Thursday Aug 21 2008 


Synopsis... 
high pressure centered over the region...will slowly drift eastward 
to the southern New England coast by midday Friday. This will allow 
dry weather to continue...with a developing southerly flow of air 
resulting in a warming trend through Saturday. A cold front will 
bring showers and thunderstorms to the region starting late Sunday. 
Drier and cooler weather will return Monday...with the possibility 
of more rain later in the week. 


&& 


Near term /through tonight/... 
a beautiful and pleasant day today with highs in the 70s was more 
like early fall than Summer...as high pressure dominated the 
region. Clear skies and calm winds will allow temperatures to 
rapidly drop toward the dew point this evening...and into the 
low to middle 50s in the valleys by daybreak Friday...with some 
middle to upper 40s across the Adirondacks...and higher elevations 
of the Catskills...Green Mountains of southern Vermont...and the 
Berkshires of western Massachusetts. Conditions will also be near ideal 
for the formation of radiation fog...especially in valleys and 
near bodies of water which are still fairly warm at this time 
of the year. 


&& 


Short term /Friday through Saturday night/... 
strong 500 hpa high over the northeastern states...592 dm centered 
over southeast New York state...remains nearly stationary and builds over the 
region Friday...then gets squeezed out as a trough rotates east from 
Canada while the remains of the tropical storm remain over the 
Gulf states. A surface ridge remains over the northeastern and 
Middle Atlantic States through Saturday. High temperatures Friday 
and Saturday generally in the lower 80s...but a bit cooler in the 
surrounding mountain regions. Friday night will again see very 
favorable conditions for radiational cooling...so have indicated 
patchy fog in valleys and near bodies of water. It will not be 
as cool as tonight...with lows near 50 in the Adirondacks and 
in the upper 50s in the Mohawk...Hudson...and Housatonic valleys. 
A cold front begins to approach the Niagara Frontier late Saturday 
night. The GFS and European model (ecmwf) are a little more progressive on the front 
than HPC at the moment. It appears that high clouds ahead of the 
front will begin to move in late Saturday...so lows Saturday 
night will be a few degrees warmer...from the middle 50s to the low 
60s. 


$$ 


Long term /Sunday through Thursday/... 
a shortwave trough will approach the northeastern Continental U.S. For the 
start of the extended period. At the surface...a fast moving cold 
front will cross the region late Sunday into early Monday...with a 
broken band of showers and thunderstorms. Temperatures will be warm 
ahead of this boundary on Sunday...as h850 temperatures of +14 to +16 c 
should translate to middle 80s in the valleys. Behind this 
boundary...h850 temperatures will plummet...bottoming out at +8 to +10 c 
for Tuesday. Dry weather should dominate from Monday afternoon through at 
least early Thursday as a large area of high pressure slowly moves 
from the Great Lakes eastward to off to New England coastline. 
Temperatures will slowly warm during this time period as well...with 
increasing amounts of humidity each day as well. Will watch to watch 
what happens with the remains of ts Fay. At this point...it appears 
that the leftover circulation and moisture will meander across the 
Gulf Coast states until at least midweek...so it may take until late 
week or even the weekend until we see any tropical-enhanced showers 
occurring in our region. 


&& 


Aviation /00z Friday through Tuesday/... 
high pressure will remain in control...providing clear skies and 
mainly light winds for the next 24 hours. With clear and calm 
conditions overnight...radiation fog will develop with at least 
occasional IFR likely at kgfl starting within a few hours after 
sunset. Will mention just MVFR visibility due to br at kalb/kpou...but not 
expecting thick fog to develop. Any lingering fog will dissipate by 
around 12z...with VFR conditions returning with bright sunshine. 
Winds will be light and variable tonight...then becoming 
south-southeast at 5 kts or less on Friday. 


Outlook... 
Fri/Sat...VFR...no weather. Chance MVFR/IFR nighttime fog. 
Sun...mainly VFR...chance PM -shra/-tsra. 
Monday...mainly VFR...chance am -shra/-tsra. 
Tuesday...VFR...no sig weather. 


&& 




Fire weather... 
no rainfall is expected through at least Saturday night as high 
pressure remains in control. 


Relative humidities were generally 40 to 55 percent this afternoon. 
They will increase to around 100 percent tonight with widespread 
valley fog and a heavy dew on exposed surfaces overnight. The 
humidity will decrease to between 30 and 45 percent Friday...with 
the lowest values in the Hudson and Mohawk valleys. Friday night 
again will see the humidity increase to near 100 percent with 
widespread valley fog and dew...with the humidity midday Saturday 
between 35 and 45 percent. Winds will be near calm tonight and 
again Friday night...and light from the south on Friday and 
Saturday. 


The keetch-Byram drought index was less than 300 over most of the 
region. 


&& 


Hydrology... 
no rainfall is expected through midday Sunday. Flows will diminish 
on rivers in the Adirondacks and remain low on other rivers. There 
will be a chance of thunderstorms starting Sunday afternoon as a 
cold front approaches the region. Locally heavy rain is possible 
but overall less than half an inch of rain is expected through the 
middle of next week. 


&& 


Aly watches/warnings/advisories... 
CT...none. 
New York...none. 
Massachusetts...none. 
Vermont...none. 


&& 


$$ 
Synopsis...rck/jpv 
near term...rck 
short term...rck 
long term...frugis 
aviation...jpv 
fire weather...rck 
hydrology...rck