Weather

188 
fxus61 kcle 070832 
afdcle 


Area forecast discussion 
National Weather Service Cleveland Ohio 
432 am EDT sun Sep 7 2008 


Synopsis... 
an upper air disturbance will cross the lower Great Lakes this 
morning and trigger a few showers. High pressure from the plains 
states will spread east across the Ohio Valley by late today and 
then shift east off the East Coast on Monday. Low pressure is 
expected to develop over the Mississippi Valley and move across the 
central Great Lakes Monday night with the trailing cold front 
swinging across the area Tuesday morning. 


&& 


Near term /until 6 PM this evening/... 
relatively deep trough over the nations midsection lifting east-northeast. Weak 
low pressure at the surface is not impressive. Track should take the 
wave across the central Great Lakes. Airmass over the area is fairly 
dry and no Gulf inflow into the system. Quite a bit of showers 
currently over central Illinois and northern MO. Some of this will likely 
dry out as we do not have much of a low level jet or surface 
convergence but there is a nice jet entrance region aloft with 
trough and models predict quite a bit of upward vertical velocity this morning. Expect 
showers to spread across Northwest Ohio early this morning and brush the 
northern counties as system tracks east-northeast today. Most of the rain 
should be east of Toledo by late morning and east of Cleveland early 
this afternoon and east of Erie around middle afternoon. Rainfall 
amounts will be generally light but certainly will be enough to wet 
things down especially farther north toward Lake Erie. Might just be 
a few sprinkles around Route 30 and points south. Clouds and shower 
will hold temperatures down a good part of the day NE Ohio/northwest PA. Will forecast 
maximum temperatures a category or so under guidance. With sunshine returning 
across Northwest Ohio this afternoon will stick closer to guidance with middle 
to upper 70s. 


&& 


Short term /6 PM this evening through Wednesday night/... 
should become mainly clear tonight. Models forecast a south to 
southwest breeze to persist and dewpoints will hold in the 50s so 
the bottom should not all out of temperatures. Min temperatures generally in the 
lower and middle 50s although colder outlying areas could slip into 
the 40s. 


Nice west-southwest flow on Monday ahead of the next cold front. Airmass is not 
all that cool and should see temperatures bounce to around 80 across Northwest 
Ohio and middle to upper 70s elsewhere. Cannot rule out a shower or 
tstorm late in the day Northwest Ohio. 


Models have diverged on their timing with cold front on Monday 
night/Tuesday. Low pressure is deeper over the Great Lakes and the 
front is slower. The NAM/WRF is the odd model out and does not bring 
the front through until midday Tuesday. The other models are faster 
with frontal passage Monday morning. Forecast will be based on 
somewhat faster frontal passage...it is closer to consensus and 
have no Faith in the NAM/WRF beyond 36 hours. This means that 
Tuesday will be cooler with temperatures struggling to get much above 70. 


Cold enough for lake effect clouds later Tuesday and with a north 
flow the bulk of the clouds will likely occur over the central 
Lakeshore from Vermilion to Painesville including Cleveland. 
Increasing anticyclonic boundary flow will likely keep shower 
activity to a minimum and for now will continue with slight chance 
(15-24 pop) later Tuesday into Tuesday night. Dry and relatively cool by 
Wednesday as high pressure spreads across the lower lakes. 


&& 


Long term /Thursday through Saturday/... 
high pressure moves off to the east allowing next system to push 
east toward the forecast area. Low pressure center is prognosticated to 
move east into the central Great Lakes by Friday afternoon with 
trailing cold front expected to push through the area some time on 
Friday. Front appears to be very weak...almost to the point that it 
washes out over the area on Friday. Moisture and upper level 
shortwave dont appear to be lacking so threat for showers and 
thunderstorms still expected across the area. 


A little bit of drier air is expected to push south into the region 
on Saturday and most of the day could escape dry. Due to timing 
differences...will just keep a mention of a chance of showers and 
thunderstorms going during the day for now. 


Warm front prognosticated to lift northeast into the region Saturday night 
into Sunday bringing with it another shot for precipitation. Will 
continue with a chance for showers and thunderstorms Saturday night 
and just a chance of showers for Sunday. 


Made a few adjustments upward in temperature for slightly warmer 
trend through this period. 


&& 


Aviation /08z Sunday through Thursday/... 
clear skies allowing temperatures to drop to dew points and some 
fog will develop before morning over the east. Visibilities will 
drop to MVFR except IFR over Youngstown area and then gradually 
improve in the day light hours. 


Upper level shortwave will race east across the central Great 
Lakes region and force some middle level clouds and showers into the 
area this morning into the early afternoon. Best upper level 
support should remain north of the area for the heaviest rain 
activity. Activity moves east of the area this afternoon with 
return to VFR ceilings and visibilities. 


Outlook...VFR weather should prevail from Sunday night until a 
low and cold front move through the area Monday night into Tuesday 
when more areas of MVFR are expected in showers and possible 
thunderstorms. High pressure to provide widespread VFR Wednesday 
then a chance for more areas of MVFR should return late Thursday 
into Thursday night as scattered showers and thunderstorms develop. 


&& 


Marine... 
west to southwest flow will develop in the wake of the surface 
trough across the lake. This should briefly bring waves up to 2 to 
4 feet on the east end of the lake today. Winds are expected to 
diminish later tonight but wave should remain up as flow remains 
westerly. Increasing southwest flow for Monday will cause waves to 
pick up again with possible small craft advisories needed going into 
Tuesday and Wednesday. 


&& 


Cle watches/warnings/advisories... 
Ohio...none. 
PA...none. 
Marine...none. 


&& 


$$ 
Synopsis...kosarik 
near term...kosarik 
short term...kosarik 
long term...Lombardy 
aviation...Lombardy 
marine...Lombardy 

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