Weather

426 
fxus61 kcle 060441 
afdcle 


Area forecast discussion 
National Weather Service Cleveland Ohio 
1141 PM EST Monday Jan 5 2009 


Synopsis... 
high pressure over the Ohio Valley will move east overnight. This 
will allow a storm system to move north out of the Tennessee Valley 
on Tuesday into the lower Great Lakes on Wednesday. The low will 
move to the New England coast on Thursday. 


&& 


Near term /until 6 am Tuesday morning/... 
increasing clouds...temperatures in the cloudy areas may not drop 
too much more...while in the north it could drop a little more. 


&& 


Short term /6 am Tuesday morning through Wednesday night/... 
issued a Winter Weather Advisory for the southern portion of the 
forecast area. Many questions still abound on how quickly it will 
warm. The 00z run of the NAM is now much quicker on warming things 
up. This will have to be monitored. Did not issue for the rest of 
the area as questions on the precipitation type and timing abound. 


Well anticipated storm system moving toward the Ohio Valley 
through the short term. Tuesday morning the surface high moves 
east off the New Jersey coast. Low pressure over the Gulf coastal 
states will move into the Tennessee Valley Tuesday and through the 
Ohio Valley Tuesday night. The NAM takes the low through eastern 
Ohio while the gfs's track is through central Ohio. The NAM also 
shows the low weakening as it moves through the area...translating 
the energy to the developing East Coast low while the GFS actually 
strengthens the low as it crosses through Ohio. Will merge the two 
models in that the low should maintain itself as it moves through 
the area although will energy should also translate to the coast 
as it frequently does. Big problem will be p-type. Expect northwestern 
Ohio to remain mostly snow. Otherwise both models show warm air 
aloft working into the rest of the area with tuesday's initial 
snow turning to rain/freezing rain and sleet late Tuesday and 
overnight Tuesday night. Can see an inch or two of snow during the 
afternoon Tuesday. With another inch northwest Tuesday night. Models 
differ on the amount of cold air that fills in behind the system 
Wednesday with the NAM colder that the GFS. Will follow the GFS 
here in that if energy does translate to the coast...cold 
advection usually gets a boost. Will also however allow for an 
afternoon mix east half to account for daytime temperatures in the 
middle/upper 30s. Will likely need an advisory to take into account 
the mixture of p-type but will differ issuance to later shift 
given the time before onset. 


&& 


Long term /Thursday through Monday/... 
low pressure will be departing the area Thursday morning but as can 
be expected with ample troughiness across the eastern lakes...les 
should be ongoing through Thursday and Thursday night. Both the GFS 
and the Euro show departing low pressure so likely probability of precipitation across the 
snowbelt Thursday and Thursday certainly seem warranted. Friday is a 
tough call as high pressure will try and sneak into the southwestern 
counties...but low pressure will be quick to follow. Another round 
of snow appears possible as early as Friday night and I bumped up 
probability of precipitation accordingly. Snow to last through Saturday and across the 
snowbelt counties on Sunday before drying out at all sites Sunday 
night. Another wave will arrive on Monday and I introduced low 
chance probability of precipitation Monday and Monday night. 


Temperatures through the extended look chilly...especially if any sort of 
appreciable snow pack develops. 


&& 


Aviation /06z Tuesday through Saturday/... 
VFR conditions will prevail across the forecast area through 
tomorrow morning. High clouds continue across the area but 
ceilings will gradually lower through the next 12 hours. I am 
anticipating some precipitation to begin spreading into the 
forecast area early tomorrow afternoon and spread east through the 
rest of the afternoon. Models are being a little more aggressive 
with the warm air at the surface and aloft and I will go ahead and 
introduce more freezing rain to Toledo and Findlay terminals. 


Precipitation type will be a mix of freezing rain...sleet...and 
snow over the eastern two thirds of the area. Warm air advection 
will take place aloft and quickly set up the area for the mixed 
precipitation. I anticipate enough warm air will move into the 
region to change the precipitation over to all rain tomorrow 
evening from Cleveland and Mansfield east. Low track over the 
forecast area will likely cut precipitation off at Cleveland and 
Mansfield for a short period of time at the end of the taf period. 


Visibilities will drop to MVFR across the area as the 
precipitation increases over the area. 


Outlook...Lake effect will set up east of Cleveland Wednesday. 
Lake effect to continue through Thursday as a series of troughs 
rotate over the Great Lakes. Next best chance for VFR Friday...as 
high pressure moves over the Ohio Valley/lower Great Lakes. 


&& 


Marine... 
the remaining small craft conditions east of Avon Point should be 
able to diminish by late evening or shortly thereafter as high 
pressure ridging moves across Ohio. Light and changeable winds 
early Tuesday are expected to settle into primarily an east flow 
later Tuesday and increase Tuesday evening. A complex low pressure 
system is expected to move through the Lake Erie area Wednesday with 
the track of the low in question so exact wind directions on Lake 
Erie are in doubt until Wednesday afternoon when the low should be 
northeast of the lake and the flow should line up out of the SW then 
west. With the low deepening...winds on Lake Erie look to be near 
gale force Wednesday evening into Thursday evening before some diminishing 
takes place Thursday night as weak ridging moves up the Ohio Valley. 


The models indicate a low and cold front moving through the lake 
later Friday night into Saturday but again show differing tracks for 
the low so for now expect a general SW or S flow ahead of this 
system turning west and increasing on Sat...possibly to gale or near 
gale force. 


&& 


Cle watches/warnings/advisories... 
Ohio...Winter Weather Advisory from 9 am to 7 PM EST Tuesday for 
ohz027>032-036>038-047. 
Winter Weather Advisory from noon to 10 PM EST Tuesday for 
ohz020>023-033. 
PA...none. 
Marine...none. 


&& 


$$ 
Synopsis...tk 
near term...kieltyka 
short term...kieltyka/tk 
long term...leins 
aviation...Lombardy 
marine...Adams 

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