522 
fxus61 kaly 051948 
afdaly 


Area forecast discussion 
National Weather Service Albany New York 
348 PM EDT Sat Jul 5 2008 


Synopsis... 
our region will be between high pressure to the north and a 
stationary front just to our south through tomorrow. The most 
unsettled weather will remain south of Albany...with mainly dry 
pleasant weather north of Albany. The front will become just a 
trough of low pressure over the region Sunday night...and drift 
north Monday. Atlantic high pressure will control our weather 
later Monday into the middle of next week...with southwest winds 
and warmer...more humid weather over our region. There will be 
gradually increasing chances for showers and thunderstorms each 
afternoon. 


&& 


Near term /through Sunday/... 
upper impulse over western New York/PA supporting some scattered 
showers along a tight moisture gradient across southern 
New York...MA...southern Vermont and New Hampshire. Tight moisture gradient seen in 
moisture fields above the boundary layer in area 12z 
soundings...and resolved in all guidance. Showers will be 
acknowledged in forecast for southern Vermont and Berkshires. 


Guidance sources also suggest the tight moisture gradient holds 
nearly stationary through tomorrow...then drifts north late Sunday 
night and Monday. The better low-level forcing associated with the 
deeper low-level moisture...surface through boundary layer...will 
be in areas from the Catskills to the southern Berkshires and 
points south through Sunday...seen in forecasted evolution of low- 
level Theta-E. So...better chances for scattered activity tonight 
over those areas. 


Slowly increasing low-level moisture...and periods of cloud cover 
in central and southern areas will result in lows a degree or two 
higher than last night. Proximity of tight moisture gradient may 
support some fog in central areas...and less subsidence tonight 
should result in lows a couple of degrees warmer than last 
night...even in northern areas...but still in the upper 40s to 50s 
in northern areas. 


Overall steering flow for systems is very weak...so movement and 
timing of moisture gradient...weak upper impulses...and any 
enhanced forcing to produce showers is very nebulous through 
Sunday. 


&& 


Short term /Sunday night through Tuesday/... 
some loose consensus that another upper impulse heralds a slight 
amplifying of the upper ridge off the eastern U.S. Which would 
push moisture gradient north and help warm and moisten low-levels 
across our region. The forcing associated with the push northward 
of the moisture gradient should spread the solid chances for 
showers and storms northward across most of the region late Sunday 
night and Monday. Southerly boundary layer flow Sunday night... 
should become more west to southwest through Monday...which 
suggests breaks of sunshine spreading across the area through 
Monday afternoon...helping temperatures rise into the 80s...but 
with potential limited sunshine in the morning...highs a little 
below guidance. 


Very weak...deep west to southwest flow...and lack of organized 
upper energy suggests partly sunny...warm and humid Monday night 
and Tuesday. Instability and humidity will support pulse type 
isolated showers and storms in some parts...but better coverage 
over northwestern areas...more proximate to increasing boundary 
layer flow associated with approaching system from western Great 
Lakes. Highs Tuesday well into the 80s to around 90...some lower 
90s some southern areas. 


&& 


Long term /Tuesday night through Saturday/... 
we begin the long term portion of the forecast with a nice surge of 
warmer and more humid airmass in advance of upstream upper trough. 
With 850mb temperatures climbing toward +20c and precipitable waters  in excess of 1.50 
inches...it will be a muggy Tuesday night. Overnight lows will be 
within a couple of degrees of 70f. With the expected warm advection 
and elevated instability...expect the chance for showers/storms 
through the night. 


Timing of the cold frontal passage remains in question for middle week but 
ensemble data reveals a bit slower progression than those offered by 
the operational control runs. The GFS was discounted given the 
convective complex that develops over the plains and maintains 
itself across the Great Lakes and into New England Wednesday night. 
So will hold onto the high chance probability of precipitation with showers and 
thunderstorms for Wednesday. 


Frontal passage will occur Wednesday evening yet some of the ensemble data 
does reveal a weak Post-frontal trough lingering across the Great 
Lakes overnight which might have minor implications heading into 
Thursday. This could lead toward a rogue shower developing on 
Thursday yet quantitative precipitation forecast members are rather dry and will retain a dry 
forecast at this time. Temperatures and dewpoints will cool off 
nicely with mainly upper 70s and lower 80s for high temperatures. 


Thereafter...followed guidance from HPC with high pressure settling 
into the Great Lakes and eventually into New England for the 
remainder of the period. Temperatures will be seasonable heading 
into next weekend. 


&& 


Aviation /19z Saturday through Thursday/... 
a stationary front remains aligned along the Long Island and 
southern New England coast with surface high pressure slowly drifting 
eastward from the central Great Lakes region. The main challenge with 
the terminals for the rest of the afternoon through the evening will 
be skycover and the formation of mist/fog. 


We are expecting VFR conditions from kalb northward to kgfl until 
0400 UTC-0600 UTC where mostly clear skies and calm winds should 
allow for radiational mist/fog formation with MVFR/IFR visibilities. The 
better chance for IFR/LIFR visibilities/ceilings will be at kgfl. The mist or 
fog should burn off quickly after 1200 UTC/sun. 


Kpou is still enduring some low stratus from the marine air 
intrusion north of the stationary front. The MVFR ceilings should erode 
by 2000 UTC...and in time the middle and high level cloud decks should 
break up some. However...after 0600 UTC...some showers in the 
vicinity...MVFR visibilities/ceilings are likely again with another impulse 
riding along the front. 


Overall...winds will not be an issue with light winds under 5 kts 
this afternoon. The winds will go calm overnight...and will be 
light from the S/southeast at 5 kts or less after 1200 UTC/sun. 


Outlook... 
Sunday PM through Wednesday...VFR/MVFR...chc shra/tsra...mainly PM and 
evening. 


&& 


Fire weather... 
expect unsettled weather at times along and south of Albany...as 
tonight and tomorrow. Tomorrow...as the front begins to lift...the 
threat of showers and thunderstorms will drift north. 


Relative humidity values will be remain higher than yesterday...only dropping into 
the 55 to 70 percent range in our southern areas...and 45 to 60 
percent across the Adirondacks. Full recovery expected tonight 
with either dew or wetting from showers further south. Relative humidity values 
tomorrow be similar to those of today...except a bit higher north. 


The wind looks to remain fairly light and variable through the 
period. A light and variable wind tonight followed a more 
southerly wind 5-10 miles per hour tomorrow through Monday. 


Increasingly warm and humid weather can be expected through early 
next week. The threat of showers and thunderstorms will be low...but 
cannot be ruled out especially in the afternoon and evening. 


&& 


Hydrology... 
no major hydrological concerns are expected throughout the period. 
Localized heavy rain will be a threat through the next several 
days as upper level winds remain light and precipitable waters  increase to well 
over an inch. We do not expect enough widespread heavy rainfall to 
impact overall water sheds...but any heavy shower or thunderstorm 
could produce localized sharp rises in smaller creeks as well as 
ponding of water on roads and areas of poor drainage. The next 
chance for organized showers and thunderstorms with more 
widespread heavy rains looks to be Wednesday afternoon through 
Thursday. 


&& 


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


&& 


$$ 
Synopsis...NAS 
near term...NAS 
short term...NAS 
long term...bgm 
aviation...taw 
fire weather...NAS 
hydrology...NAS 

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