612 
fxus61 kcle 201838 
afdcle 


Area forecast discussion 
National Weather Service Cleveland Ohio 
238 PM EDT Sat Mar 20 2010 


Synopsis... 
a cold front across Northern Ohio will drop slowly south to the 
Ohio River by Sunday morning and then stall. Low pressure will 
strengthen in the lower Mississippi Valley tonight and Sunday 
before moving northeast along the front into the lower Ohio Valley 
Monday. The low will move through the region Monday and Monday 
night before moving east Tuesday. 


&& 


Near term /through tonight/... 
cold front quite apparent on the satellite with convective 
cumulus along and to the south of the boundary. Mostly clear skies 
are to the north across much of Northern Ohio with stratus and 
precipitation north and west of the region. Cape values across the 
frontal zone are around 100 g/kg so done expect thunder to develop 
however seasonally not that far away. Done completely trust the cumulus 
however and will have a 40 pop for northwest and 30 elsewhere. In the 
south for the possible passing shower early as well as anything 
out of the approaching moisture from the northwest. In the north will 
have the pop for the moisture approaching from the northwest. Temperatures 
adjusted south to be a degree or two above MOS. 


&& 


Short term /Sunday through Tuesday night/... 
guidance shows increasing moisture overnight into Sunday morning 
with moisture deepest across the north. Expect a few breaks 
possibly across the south with cloudy skies north on Sunday. 
Low/middle level flow will be overrunning the front to our south 
however best chance for rain should be in the afternoon southwest with 
the surface low closer to the area. Held probability of precipitation to chance/slight 
chance category with a continued lack of significant forcing. 
Sunday night models similar however the GFS is a 150 km faster. No 
big difference but will follow the GFS position from here out. 
Overnight Sunday night models Show Low level moisture convergence 
increasing with deep moisture across the area and the low 
approaching southwestern Ohio. Have went with categorical probability of precipitation across the 
S/SW with likely probability of precipitation elsewhere. Monday the low moves into eastern 
Ohio. Will continue with the Cat probability of precipitation theme across the east half 
of the area. Will taper probability of precipitation back to chance in the far west. 
Tuesday the low moves to the Delaware-Maryland-Virginia with much drier air moving 
in from the west. Will have a slight chance in the graphics 
central and east in the morning. And a slight chance in the east 
for the afternoon. Otherwise the challenge will be just to lower 
cloud amounts. Expect dry and decreasing clouds Tuesday night. While 
the front will be south of the area Sunday and Monday still expect 
a sharper than usual temperature gradient provided by the lake and a 
north/northeast flow. Attempted to depict this by increasing the 
range from MOS numbers. 


&& 


Long term /Wednesday through Saturday/... 
haven't had a chance to look at the new European model (ecmwf) but the long term 
models appear to be trending drier for the period. Wednesday and 
Thursday will be dry with surface high pressure over the region. A 
stationary boundary is expected to be just south of the region 
Thursday night into Friday. Latest GFS keeps precipitation south 
of the area with old European model (ecmwf) showing very light precipitation over the area. 
Have a feeling the new European model (ecmwf) will also be slightly further south 
with the boundary and have eased off on precipitation chances slightly. 
Will need to keep a mention of mixed precipitation for late Thursday night 
and Friday morning. Any precipitation that does fall will be very light so 
no accumulation expected. Dry weather will return for Friday night 
and Saturday as high pressure begins to build over the local area 
again. Temperatures will start out the period a little above normal on 
Wednesday but by Saturday will actually be a degree or two below 
normal. 


&& 


Aviation /18z Saturday through Thursday/... 
MVFR strato cumulus made it to ktol a few hours ago and remains in 
place early this afternoon. Dry NE flow has kept this low cloud 
from spreading east across the remainder of the area. As winds 
lessen toward evening expect the low cloud to spread east and southeast 
across the remainder of the area. By 06z or so much of the area 
will have MVFR ceilings. Frontal system is just south of the area and 
have started to see some cumulus developing. An isolated rain showers cannot be 
ruled out this afternoon at places like kmfd and kcak which will 
be closest to the front. Also could see some light rain showers spread 
into Northwest Ohio later in the evening. With the dry NE flow think the 
remainder of the area will remain dry through the end of the taf 
period. Models show level moisture retreating north on Sunday. 
Will try to improve ceilings to VFR Sunday am with some sunshine 
possible all areas for the end of the taf period. More widespread 
precipitation will have to wait till well after the taf period ends. 


Outlook...non-VFR conditions with occasional rain showers will 
increase Sunday night and Monday. MVFR ceilings could linger NE 
Ohio on Tuesday otherwise improving conditions Tuesday and 
Wednesday. 


&& 


Marine... 
NE to north flow continues on Lake Erie and will do so for the next 
couple of days at least. Expect winds to begin to pick up on Sunday 
and by Sunday night will need the first small craft of the season. 
The flow will gradually become north and weaken on Tuesday. By the 
middle part of the week the flow will again be light and variable as 
a surface ridge moves over the lake. The flow will become NE 
Wednesday night into Thursday as another low pressure system begins 
to approach the lake from the distant SW. 


&& 


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


&& 


$$ 
Synopsis...tk 
near term...tk 
short term...tk 
long term...kubina 
aviation...kubina 
marine...kubina