299 
FXUS61 KCLE 111743
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
143 PM EDT Thu Jul 11 2024

...18z TAF Aviation Forecast Update...

.SYNOPSIS...
A trough will linger near Lake Erie this morning before high
pressure builds into the southern Great Lakes this afternoon and
persists through tonight. A weak trough will cross the region
Friday into Friday night followed by high pressure returning
Saturday. A warm front will approaching from the west Sunday.

&&

.NEAR TERM /THROUGH FRIDAY/...
9:35 AM Update...
The only minor adjustments we made to the near term hourly
forecast was tweaked the cloud cover and the slight POPs 
through the early afternoon hours. We may hold on to the lake 
effect clouds a little longer into the afternoon than the 
previously forecast had indicating over far NEOH and NWPA. 
Otherwise, the rest of the forecast is on track with no other 
changes needed at this time.


6:30 AM Update...

Increased PoPs over NE Ohio and NW PA over the next few hours to
account for the lingering surface trough and light lake 
enhanced showers. Otherwise, the forecast remains on track.

Original Discussion...

Light showers and drizzle continue early this morning from north 
central Ohio into NE Ohio and NW PA. They are not amounting to much 
more than a trace to up to a tenth of an inch, but they are keeping 
things wet with a muggy feel to the air. The light rain is being 
driven by wraparound moisture on the backside of the remnant surface 
low from Beryl, currently centered near Lake Ontario, a weak surface 
trough near the south shore of Lake Erie, and weak lake induced
instability given an 8-10 C lake to 850 mb delta T and 
northwesterly boundary layer flow. The old surface low will 
continue to fill and move across New England today allowing 
surface high pressure centered over the western Great Lakes this
morning to build over the southern Great Lakes this afternoon 
and tonight. This will bring a gradual end to the showers this 
morning along with clearing skies from west to east, but 
lingering moisture and the surface trough will make it a very 
slow process in far NE Ohio and NW PA, so held onto slight 
chance to chance PoPs into the early afternoon. Even NE Ohio and
NW PA should see sunshine by late afternoon as the drier air 
finally wins out. The clearing skies and lower dew points will 
allow for a cooler night tonight, so the air conditioners can 
get a break. 

For Friday, a stubborn mid/upper closed low over the Upper 
Mississippi Valley will open up into more of a shortwave trough and 
finally swing into the central Great Lakes, with an associated 
surface trough moving into western Ohio. Weak warm air advection 
ahead of this feature combined with mid/upper subtropical ridging 
over the Mid Atlantic coast building slightly westward will bring a 
quick return to warmer and more humid conditions Friday. Strong 
boundary layer heating of the increasingly moist low-level airmass 
will generate weak to moderate instability (500-1000 joules of 
MLCAPE), so expect a few widely scattered showers and thunderstorms 
to develop in NW and north central Ohio near the surface trough, 
especially from mid morning into the afternoon. Shear will be very 
weak, generally under 20 knots in the 0-6 Km layer, so any 
convection is not expected to be severe or very organized. It will 
be pulse-type convection that will move slowly and be relatively 
short-lived. Any convection will dissipate Friday evening.

Highs in the mid 70s to low 80s today will warm into the mid to 
upper 80s Friday. Lows will fall into the low 60s tonight, with a 
few upper 50s in interior NW PA.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
High pressure overhead on Friday night gradually drifts east to the 
mid-Atlantic region by Saturday, which should result in largely 
quiet conditions through at least Saturday night. There is a low 
chance for isolated showers and thunderstorms but confidence wasn't 
high enough to quite put it in the forecast. Southwest flow behind 
the departing high will result in gradually increasing temperatures 
and moisture with mid to upper 80s expected on Saturday.

Northwest flow aloft develops on Sunday with subtle shortwave 
troughs expected to traverse the Great Lakes region Sunday onward. 
Heat and humidity continue to build with temperatures touching 90 by 
Sunday afternoon. PoPs increase to the 20-40% range Sunday and 
Sunday night with timing greatly depending on shortwave timing. 
Thunderstorms that occur in the afternoon/evening would likely pose 
at least a low severe weather threat as most models have pretty 
decent instability with low but sufficient deep layer shear.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
Northwest flow pattern continues through the long term with several 
shortwaves expected. Heat and humidity remains relatively unchanged 
with temperatures in the low 90s and dew points in the low 70s, 
combining for max heat indices in the mid 90s to around 100. 
Thunderstorms are expected, though timing and coverage are extremely 
uncertain, so held with a broad 20-50% PoPs through every period in 
the long term. Details will become more apparent as we get closer. 
Severe thunderstorms will be possible as high dew points contributes 
to potentially substantial instability (alongside low to moderate 
deep layer shear). Previously most models had an upper-level trough 
swinging down crossing the Great Lakes by Wednesday, but there are 
now a few more solutions starting to slow this trough down, which 
would add another day of heat, humidity and thunderstorm chances. 
However, ensemble average favors lower temperatures and 
precipitation chances for Wednesday.

&&

.AVIATION /18Z Thursday THROUGH Tuesday/...
Most of northern Ohio has cleared out of the thicker lake effect
cloud cover with VFR conditions this afternoon. There is still a
pocket of MVFR ceilings due to lake effect clouds over far NEOH
and NWPA impacting YNG and ERI this afternoon. We expect these
areas to eventually break out of the MVFR ceilings and scattered
out the clouds later this afternoon into the early evening
hours. All areas will be VFR tonight into Friday morning. There
could be a little light fog around ERI after 06z tonight and
have this possibility mentioned in a TEMPO group for 5sm light
fog or BR through about sunrise. Some mid level cloudiness may
move into NWOH by Friday morning and there could be a couple
isolated rain showers around TOL and FDY but think the overall
chances are too low to mention in the TAF at this time for those
locations. 

Winds continue to slowly decrease this afternoon out of the
north and northwest 10 knots or less. Winds will be become
lighter tonight under 5 knots. Most areas will either have light
and variable winds or nearly calm conditions this evening into
the overnight. A light southeast winds may return 5 knots or
less over northwest and north central Ohio by Friday morning. A
lake breeze will shift the winds from the north-northeast by
midday or early afternoon for CLE and ERI about 8 knots or less.

Outlook...Isolated showers/thunderstorms with non-VFR possible
in NW Ohio Friday. Periodic rounds of showers and thunderstorms
with non-VFR may be possible this Sunday through Tuesday.

&&

.MARINE...
Northwest winds are past their peak and should gradually diminish 
through the day today as high pressure gradually builds in from the 
west. As such, we should be able to gradually chip away at the small 
craft advisories and beach hazard statements, with all marine 
headlines gone by 20Z. High pressure lingers through Friday before 
departing to the east coast Friday night. Southwest flow develops by 
Sunday which is expected to last through midweek. There is a low 
chance that periods of 20 knots winds within this southwest flow, 
though uncertain when the best chance for this to occur.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement until 4 PM EDT this afternoon for 
     OHZ011-012-089.
PA...Beach Hazards Statement until 4 PM EDT this afternoon for 
     PAZ001.
NY...None.
MARINE...Small Craft Advisory until 4 PM EDT this afternoon for 
     LEZ146>149.

&&

$$

SYNOPSIS...Garuckas
NEAR TERM...Garuckas/Griffin
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...Griffin
MARINE...Saunders