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Area forecast discussion 
National Weather Service Buffalo New York 
737 am EDT Monday Oct 13 2008 


Synopsis... 
beautiful Fall weather will continue today as strong high pressure 
centered over the Middle Atlantic States will keep temperatures some 
15 to 20 degrees above normal. In fact...temperatures today will 
aproach record levels in many areas. A weak cold front will then 
move through the region late Tuesday and Tuesday evening and this 
could produce a couple light showers. Following the front...much 
cooler weather will return for the second half of the week into the 
upcoming weekend. 


&& 


Near term /through tonight/... 
Summer-like conditions will be the rule again today as high 
pressure centered over virgina remains in control of our weather. 
With 850 mb temperatures forecast to hover around +16c...area 
temperatures will have no problem warming well into the 70s during 
the afternoon. In fact...if it wasn't for all the cirrus spilling 
across the upper level ridge...area temperatures might have a good 
chance of eclipsing record highs across parts of the Genesee Valley. 
For now...will follow the slightly cooler trend indicated by the GFS 
MOS guidance. 


A back door cold front is forecast to drift west across New 
England and eastern New York state during the afternoon. This 
front will generate more clouds across the north country...but any 
precipitation that may form along the boundary is expected to stay east of 
our County Warning Area. 


Expect the cirrus to thin out for awhile tonight as the back door 
cold moves to the east and washes out. The far western counties may 
see some increase in middle and high level clouds late tonight as the 
Central Plains cold front moves slowly to the east. 


&& 


Short term /Tuesday through Wednesday night/... 
a potent shortwave will cross the northern reaches of Ontario on 
Tuesday and this will knock down the anomalous ridge that has 
brought several gorgeous days of weather to our region. A weak cold 
front trailing the upper level feature will cross Michigan and 
southern Ontario early in the day and will be on our doorstep by 
late afternoon. 


While clouds will be on the increase ahead of this frontal system on 
Tuesday...850 mb temperatures of 10/12c will keep our Mercury readings well 
above normal. Temperatures are expected to peak in the middle 70s for 
the majority of western and north central New York. 


The upper level support for the frontal system will be sheering out 
across the province of Ontario late Tuesday...and the system is now 
forecast to be a bit slower...so have removed the chance probability of precipitation that were 
in continuity. At this point we only expect isolated -shra activity 
towards day end. This solution is a compromise between the very dry 
21z sref solution and the typical .01 broadbrush of the GFS. 


For Tuesday night...weak surface convergence and limited Omega with the 
passing front could touch off a shower or two early otherwise the 
vast majority of the region should only experience mostly cloudy 
skies. 


A zonal flow will then be found across the Great Lakes in the wake 
of the front for Wednesday. With the lack of any forcing and the 
presence of a flat middle level ridge...have removed the chance probability of precipitation that 
were in continuity and have replaced them with slight chance for all but 
the north country. 850 mb temperatures will be around 8c...so maximum temperatures will 
be in the 60s rather the 70s/near 80 like the previous several days. 


As is the case in a zonal flow...a difficult to time weak shortwave 
is forecast to zip across the Great Lakes region Wednesday night. 
This could touch off some shower activity. I leaned more towards 
pattern recognition and away from the 21z sref solution...which 
again looked too 'dry'. 


&& 


Long term /Thursday through Sunday/... 
after a rather lengthy spell of warm weather...temperatures will 
drop back to near normal or slightly below normal values for this 
period as a broad low amplitude trough will prevail over the Great 
Lakes region. A look at the details... 


Expansive high pressure centered over the plains on Thursday morning 
will build across the Great Lakes in the wake of the departing 
shortwave. The associated west to northwest flow will drop 850 mb temperatures 
to near zero by late Thursday...then to between -2 and -4c Thursday 
night. While this will set up Lake Delta t's of about 16...the 
combination of drier air in the middle levels and the influence of a 
middle October sun should keep any lake effect showers from developing. 
Nevertheless...Thursday will certainly feel much cooler with highs 
ranging from the upper 50s to lower 60s. 


On Thursday night...a broad cyclonic flow over the eastern lakesand 
the absence of diurnal affects will team up with Lake Delta t's of 
17 to possibly produce some lake effect showers. I am somewhat 
impressed that the more coarse GFS is acvtually depicting this 
scenario...but it does make sense given the flow and instability. 
I have added chance probability of precipitation from about roc to Oswego for the night...but 
have kept any Lake Erie enhanced activity just to the west of our 
fordecast area. 


For those having visions of Oct 12-13 from two years ago...stop! 850 mb 
temperatures will be too warm for any of that. We would need 850 mb temperatures to 
drop to between -7/-8 before that would be a concern. 


For Friday and Friday night...the broad surface high over the western 
Great Lakes will remain in place as will 850 mb temperatures of about -4c. Any 
lake -shra will break up during the day due to diurnal affects...but 
there will still likely bea fair amount of cloudiness around due to 
the instability and deep cyclonic flow. 


For Saturday and Sunday...a progressive ridge over The Rockies and 
plains will flatten and make its way across the Mississippi and Ohio 
valleys. While this will eventually result in the onset of some warm 
advection later Sunday...the flavor of the weekend will be a cool 
one with clear to partly cloudy skies. 


&& 


Aviation /12z Monday through Friday/... 
VFR flight conditions will prevail through the taf period as high 
pressure centered over Virginia remains in control. Cirrus will 
continue to spill over the upper level ridge that is anchored over 
the Ohio Valley. The largest concentration of middle and high level 
clouds will be near kart as a back door cold front drifts west 
across New England. Expect the clouds to thin out from west to east 
through the first half of tonight before middle level clouds increase 
before daybreak Tuesday in advance of an approaching cold front. 


Outlook... 
Tuesday through Friday...generally VFR. Chance of some showers 
Tuesday night/Wednesday but should still be VFR. 


&& 


Marine... 
no marine flags are expected through at least Tuesday night. 


High pressure over the Carolinas today will produce gentle 
southwesterly breezes across both lakes Erie and Ontario...with 
minimal waves making for nearly ideal boating conditions. 


Relatively light winds will remain in place over the lower Great 
Lakes tonight...then the surface pressure gradient will increase ahead 
of a cold front on Tuesday. This will result in moderate to fresh 
southwersterlies on Tuesday...with waves remaining below small craft 
criteria. 


&& 


Buf watches/warnings/advisories... 
New York...none. 
Marine...none. 


&& 


$$ 


Synopsis...rsh 
near term...tjp 
short term...rsh 
long term...rsh 
aviation...tjp 
marine...rsh 

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