CLE issues Area Forecast Discussion (AFD) at Sep 27, 3:35 PM EDT
883
FXUS61 KCLE 271935
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
335 PM EDT Fri Sep 27 2024
.SYNOPSIS...
Tropical remnants from Helene will continue to weaken over the
Ohio Valley, gradually shifting to the east throughout the
weekend and into early next week. A cold front may move east
across the area on Tuesday before high pressure settles in for
the end of the work week.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
Remnants of Tropical Storm Helene have merged with an upper
level trough that extends south across areas east of the
Mississippi River. The upper level pattern is forecast to
progress very slowly with weak resemblance of a blocking
pattern developing. This will result in a near stationary low
pressure system over the Ohio Valley and the potential for
continued impacts through this period. Currently, the most
notable impact is from the enhanced pressure gradient across the
area which has resulted in gusty winds. Areas west of I-71 are
experiencing sustained winds of 25-30 mph, with localized gusts
up to 40 mph. Areas near the western basin of Lake Erie have the
potential to see gusts up to 45 mph, but these should remain
isolated and did not warrant a headline at this time. For areas
along and east of I-71, winds are sustained at 20-25 mph,
gusting up to 30 mph. These winds will steadily weaken
throughout the evening and into the overnight hours to
eventually be sustained on Saturday at 5-10 mph.
In addition to the wind, scattered rain showers have begun to
push north across the southern tier of counties. These showers
are expected to continue to progress north across the area, but
overall impacts should remain minimal with total QPF generally
less than 0.5". The nature of these showers will continue to
maintain "banding" and will be highly dependent on upper level
energy and overall moisture. Currently, the bulk of the moisture
is on the north and western sides of the low pressure. However,
as the low continues to pivot over the Ohio Valley, that
moisture will also pivot around the low and allow for a brief
period tonight where some dry air will sneak in. Unfortunately
with how slow the low will move, this area of moisture is
expected to again push north across the area Saturday afternoon.
With this timing of moisture, models suggest that increased
vorticity will coincide which will enhance the potential for
showers. Overall, given the widespread cloud cover and lack of
instability, have opted to take all thunder potential out of the
forecast and maintained the rain showers.
High temperatures on Saturday will climb into the low to mid
70s. Overnight lows tonight and Saturday night will remain mild,
dropping into the mid 60s.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
The main weather story for the short term period, Sunday through
Monday, will be the remnants of Helene rain itself out over the Ohio
Valley into the Mid-Atlantic region. The remnant low pressure system
will continue to interact with an upper level trough slowly moving
across the Ohio Valley region Sunday through Monday. Scattered rain
showers and a few isolated rumbles or thunder will be likely from
time to time over this time period. While rain chances will be in
the change to likely category over the two days, rainfall amounts
will be relatively light around a quarter to maybe half an inch over
the southern CWA. Temperatures will continue to be above average
Sunday and Monday with highs in the low to mid 70s and overnight
low temps in the lower 60s.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
The upper level trough and remnants of Helene will move east of the
region by early Tuesday. There will be a small upper level ridge
that quickly moves across the Ohio Valley on Tuesday. Another
slightly stronger upper level trough will swing through the Great
Lakes and Upper Ohio Valley region for the middle of next week. A
noticeable cold front will push through the region late Tuesday into
Tuesday night. High temperatures will warm up into the middle and
upper 70s ahead of the cold front on Tuesday. Scattered showers and
isolated thunderstorms will come with the cold frontal passage. A
brief push of colder air aloft with 850mb temps falling to around 3C
Wednesday will help with a few scattered lake effect rain showers
during the day. Air temperatures will be much cooler on Wednesday in
the lower to middle 60s with a breezy northwest wind 10 to 15 mph.
High pressure will move in by Wednesday night with clear skies and
cool temperatures in the low to mid 40s across the area. More nice
weather is expected next Thursday with sunny skies and temperatures
near seasonable averages.
&&
.AVIATION /18Z Friday THROUGH Wednesday/...
As tropical remnants of Helene begin to slow progression near
the Tennessee Valley, less than desirable aviation conditions
will persist. Right now across the area, there is a mix mag of
MVFR and VFR ceilings being observed with rain showers just
beginning to move into the far southern counties. Into the
evening, these showers will become more widespread as well as
ceilings are expected to begin to lower. As a result, widespread
MVFR conditions, and possibly even touching IFR, will become
prevalent by 00Z tonight. In showers, expect visibilities to
fall to around 4SM. Confidence was fairly low in where the IFR
conditions will set up tonight, so only included IFR at KYNG
and KTOL where hi-res models were most consistent in lowering
ceilings sub-1kft. Will have to continue to monitor into the
overnight hours for more widespread impacts.
An additional impact that the area will feel from Helene is the
increasing wind speed from the northeast today. Winds across the
northwest terminals, including KFDY and KTOL, have become
sustained at 20-25 knots, gusting up to 30-40 knots at times.
For terminals east of these, expect sustained northeast winds at
15-20 knots with gusts of 25-30 knots. As the tropical remnants
weaken over the Tennessee Valley tonight and allow the gradient
to weaken, winds will gradually weaken to 5-10 knots and remain
northeast-easterly by Saturday morning.
Outlook...Periods of non-VFR are possible with scattered rain
showers and low ceilings through Tuesday.
&&
.MARINE...
Gusty winds from the east-northeast 20 to 30 knots will continue to
make for rough conditions on Lake Erie this afternoon into tonight.
Some gusts may reach up to Gale Force, especially over the western
and central basin of the lake. These blustery and rougher conditions
are due to the pressure gradient associated with the remnant low
pressure system of Tropical Cyclone Helene over the Lower Ohio
Valley this afternoon and high pressure north of the Great Lakes.
Water levels on the western basin of Lake Erie will remain slightly
elevated this afternoon through the evening due to the stronger
easterly flow but we are not expecting the water levels to reach
lakeshore flood criteria at this time.
The highest winds and waves will be over the western and central
basins of Lake Erie through Saturday morning. We will leave the
Small Craft Advisories and Beach Hazards Statements as is with this
update through 12z Saturday morning. The east-northeast flow will
relax some by Saturday morning which should allow the waves to
decrease as well later Saturday morning. We will let the overnight
marine forecaster take a look if any of the headlines need to be
extended locally beyond Saturday morning. East-Northeast winds will
diminish to 10 to 18 knots on Saturday and 10 to 15 knots on Sunday.
By Monday, the winds will become from the southeast 5 to 12 and
continue into Tuesday. A stronger cold front will move through
Tuesday night with northwest winds 15 to 20 knots and higher waves
likely.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement through Saturday morning for OHZ003-
007-009>012-089.
PA...Beach Hazards Statement through Saturday morning for PAZ001.
MARINE...Small Craft Advisory until 8 AM EDT Saturday for LEZ142>149.
&&
$$
SYNOPSIS...Campbell
NEAR TERM...Campbell
SHORT TERM...Griffin
LONG TERM...Griffin
AVIATION...Campbell
MARINE...Griffin
Source: CLE issues Area Forecast Discussion (AFD) at Sep 27, 3:35 PM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202409271935-KCLE-FXUS61-AFDCLE)
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