Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 140126
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
926 PM EDT Sun Aug 13 2017

.SYNOPSIS...
High pressure centered over the forecast area will slide east and
move off the Mid Atlantic Coast Tuesday. A weak cold front will
push across the area Friday morning.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Cirrus will over spread much of the forecast area overnight...
particularly in the west.  I will remove the patchy fog in the
western areas but keep it in the east.  Short term guidance not
overly pessimistic with the fog tonight.  I have adjusted the temperatures
a few degrees down for the inland areas of Northwest PA to match current
trends and short term guidance.

Previous discussion... High pressure centered over the
forecast area will remain over the area overnight. The only
weather to contend with tonight will be area of dense cirrus
that will overspread the area this evening. Expect temps to be a
couple of degrees warmer than this morning with the additional
cloud cover. Expect some patchy fog toward daybreak but not as
widespread or dense as this morning due to the clouds and drier
air pushing in.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/...
Surface high pressure shifts East allowing for a
gradual rise in temps.   At the upper levels ridge builds over the
Great Lakes Wednesday in response to deepening west coast trough.
should keep area high and dry though mid week.

Surface high will shift east allowing for a more southerly flow to
develop over the region. Temperatures will be in the mid 80s given a
fair amount of sun. The southerly flow will increase dewpoints by 10
degrees from their current levels. The models are hinting at
convection, which continues to be overdone in this dry regime.
However there will be lake breeze convergence which could be
sufficient to produce a few isolated storms given no capping
inversion.

For Wednesday a warm front could spark a few storms as airmass
remains moist and unstable. With cyclonic flow aloft and lowering
heights the best chance will be during the afternoon. Shear however
remains weak suggesting any development is likely to be sub-severe.
The best chance will be in the west where the moisture convergence
is highest. PWATs are expected to increase to around 2" by the
afternoon. Temperatures will once again be in the mid-80s. Models
often have biases during dry periods resulting in underestimates of
the latent heating/daytime highs and overestimates in the coverage
of precipitation. Tried to account for these biases in the forecast.
With hit and miss storms much of the area may remain dry until the
more organized system Thur/Fri. &&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Ridging currently over the western U.S. will move east into the area
on Thursday. Meanwhile a trough and cold front extending down from
the upper lakes will move into the region. This could be a trigger
for more organized scattered afternoon storms as shear becomes
stronger. Timing on this feature varies notably in the models
reducing confidence.

 A weak low pressure system will move across the lakes on Thursday.
This system will drag a cold front across the forecast area Thursday
night into Friday.  The models currently show scattered convection
with the frontal passage.  Weak high pressure will briefly build
over the region on Saturday.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Ridging currently over the western U.S. will move east into the area
on Thursday. Meanwhile a trough and cold front extending down from
the upper lakes will move into the region. This could be a trigger
for more organized scattered afternoon storms as shear becomes
stronger. Timing on this feature varies notably in the models
reducing confidence.

Models begin to spread for the weekend.  In a broad sense region
continues to be under low amplitude troughiness and therefore precip
chances at some point. Differences in timing features and of course
then surface details. By late in the weekend we should get any
surface fronts through the area with high pressure taking over. So,
have silent 20 percent chances through the weekend with seasonable
temperatures.

&&

.AVIATION /00Z Monday THROUGH Friday/...
High pressure will keep mostly clear conditions over the
forecast area overnight. A few thin high clouds will stream over
the area. Patchy fog is possible in some of the traditional
locations of MFD...CAK and YNG. Model guidance is not
pessimistic with the fog chances tonight as compared to Sunday
morning. High cloud coverage may determine fog formation.
Dew point and wind conditions will be similar to last night so
fog is possibility at these locations after 09Z if high clouds
do not stream over the area.

OUTLOOK...Patchy BR possible each morning. Areas of Non-VFR possible
Wednesday evening through Thursday with scattered storms.

&&

.MARINE...
Light winds and small waves expected over the next few days as high
pressure remains centered over the area. SW flow will increase in
advance of a cold front on Thursday, but will remain below small
craft threshold.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.

&&

$$
SYNOPSIS...DJB
NEAR TERM...Garnet
SHORT TERM...DJB/Jamison
LONG TERM...Jamison/Oudeman
AVIATION...Garnet
MARINE...Jamison


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