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Area forecast discussion 
National Weather Service Upton New York 
130 am EDT Thursday Oct 16 2008 


Synopsis... 
low pressure from the Ohio Valley approaches tonight. A cold 
front associated with the low moves through Thursday into Thursday 
evening. High pressure builds from the west Thursday night into 
Friday...and remains across the region through the weekend. 


&& 


Near term /until 6 am this morning/... 
much of the area will stay mainly clear or partly cloudy for a 
good portion of the overnight. This has resulted in better 
radiational cooling conditions. Adjusted temperatures downward in 
the typically cooler spots for the first part of the overnight. 
Temperatures will likely slowly rise before daybreak as cloud 
cover moves in as a low pressure center moves from the Ohio Valley 
into central New York. The low will strengthen a bit with the help of 
shortwave energy moving along the same path. Models still look to 
be just dry enough to to keep showers out of the forecast through 
the entire night. 


&& 


Short term /6 am this morning through Saturday/... 
cold front associated with the low to the north expected to be in 
the vicinity of our northwest zones near noontime. Some moisture pooling 
ahead of the front...with some instability and cape developing in 
the afternoon...but cloud cover should limit destabilization to a 
degree. Forcing with the front should be the focus for any 
convection. Will continue with a mention of isolated thunderstorms 
during the afternoon. As for probability of precipitation...NAM has the higher 
numbers...but when blended with GFS...yields mostly lower-end 
likely probability of precipitation...which had already been in the forecast. Made only 
slight adjustments to the timing...keeping the likely probability of precipitation 
reserved for the afternoon. Went with mav MOS for highs as NAM MOS 
looked too high in some areas given the anticipated cloud cover. 


Building surface high pushes the front off the coast by 
midnight...ending any lingering precipitation west to east. It may become a 
bit breezy late with the pressure gradient tightening. 


Upper flow becomes zonal on Friday...with high pressure continuing 
to build in at the surface. Pressure gradient will relax in the 
afternoon with cold air advection weakening...but still think winds can get a 
little gusty at times. BUFKIT forecast soundings indicate mixing up 
to a little above 900 mb where temperatures are forecast to be around 4c. 
Looks like we'll have enough sunshine and downsloping for highs in 
the upper 50s to lower 60s. Used mav MOS once again...with a few 
adjustments. 


Models continue to suppress the offshore cold front to the south. 
This will keep a developing low along this front at a safe distance 
from US during Saturday as the upper flow amplifies...and a trough 
axis begins to move through the region late in the day. Will go with 
a dry forecast Friday night...and then dry again on Saturday...as it 
appears that the atmosphere will be too dry to support showers with 
the passing middle level trough. The offshore low is forecast to be close 
enough for the potential of at least a broken deck of middle-high 
clouds...so will go with a partly sunny forecast. It should be 
cooler on Saturday as there will be more clouds...and temperatures aloft 
cool down as well. Knocked a couple degrees off of gmos numbers for 
highs in the middle-upper 50s. 


&& 


Long term /Saturday night through Wednesday/... 
followed a blend of the 12z GFS and 12z European model (ecmwf) in the extended. 
Main difference is in timing/amount of moisture available with 
cold front early next week and how quickly the high behind it 
moves off to the east. European model (ecmwf) is slower/wetter with the front and 
slower/colder with the high...while the GFS is faster/drier with 
the front and faster/warmer by Wednesday with the high. Compromise 
timing/strength solution with this front and high is fairly 
similar to 00z European model (ecmwf). 


Upper level pattern will feature a departing trough to close the 
weekend...followed by zonal flow into Tuesday...then a stronger 
trough crossing the region for the middle of next week. Cold air 
will move in with the trough...however sharp ridging behind the 
trough will allow for temperatures to rebound quickly by the end 
of the work week. 


Other than a chance of showers with the cold front late 
Monday...expect the extended to be dry. Temperatures will run near 
normal Sunday and Monday...then below normal Tuesday and 
Wednesday...with lows away from urban areas in the 30s Wednesday 
morning...with upper 20s not completely out of the question in 
normally colder spots (too early to go there yet given inherent 
uncertainty in the long term). 


&& 


Aviation /06z Thursday through Monday/... 
light southerly flow prevails across the region with clouds 
lowering and thickening during the overnight. A few locations 
outside of New York City will observe MVFR fog...with kgon 
possible IFR at times. Otherwise...VFR ceilings. Low end VFR to 
possible MVFR Thursday morning ahead of an approaching cold front. 
Light south flow trends more southwest and increases to around 10 
knots as the morning progresses. 


Cold front will approach during the day on Thursday...pushing 
across the region Thursday afternoon/evening. Expect some partial 
clearing to begin to work into the region by around the time of 
sunset. 


Outlook for 06z Friday through Monday... 
VFR through the period. Gusty north winds Thursday night into Friday 
morning...and again Saturday. Gust SW winds ahead of a front 
Monday. 


... 


Taf code is changing November 5th at 00z... 


Please see... 


Http:/aviationweather.Gov/notice/taf30.Php (lower case) 


... 


&& 


Marine... 
light southerly synoptic flow tonight ahead of an approaching cold 
front. Southerly winds pick up Thursday as the front nears. Front 
clears the waters from west to east Thursday afternoon...and winds 
turn to the west...then northwest by late in the day behind the 
front. The front remains south of the waters Thursday night through 
Saturday as high pressure builds to the west. An area of low pressure 
develops on the front Saturday. Northerly winds can be expected this 
time frame...and winds will initially come close to Small Craft 
Advisory levels Thursday night in fairly tight pressure 
gradient...and cold air advection. 


Seas increase ahead of and behind the front Thursday. Little change 
in seas expected Friday and Saturday. Wave watch iii forecast 
accepted. 


With coastal low expected to stay well to the S and east to close the 
weekend...expect sub Small Craft Advisory conditions to prevail into early next week. 


&& 


Hydrology... 
dry tonight. Generally up to a couple of tenths of an inch of 
rainfall Thursday into Thursday evening. Dry thereafter. No 
hydrologic problems expected over the next few days. 


&& 


Okx watches/warnings/advisories... 
CT...none. 
New York...none. 
New Jersey...none. 
Marine...none. 


&& 


$$ 
Synopsis...jc 
near term...jc 
short term...jc 
long term...pfm 
aviation...mps 
marine...pfm/pw 
hydrology...jc 

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