Author Topic: [Alert]CLE issues Area Forecast Discussion (AFD) at Oct 10, 9:15 PM EDT  (Read 33 times)

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CLE issues Area Forecast Discussion (AFD) at Oct 10, 9:15 PM EDT

469 
FXUS61 KCLE 110115
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
915 PM EDT Thu Oct 10 2024

.SYNOPSIS...
High pressure remains over the region through Friday before a
warm front lifts east across Lake Erie. A cold front will sweep
southeastward Friday night into Saturday. Low pressure and
unsettled weather enter the region to end the weekend and begin
next week.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
9:15 PM Update...
Forecast remains on track with relatively quiet conditions under
high pressure. Frost Advisory for much of the eastern half of
the local area in effect from Midnight tonight to 9 AM Friday
morning. Overnight low temperatures along and east of I-71 will
dip into the low to mid 30s, 40s along the Lake Erie lakeshore.

Previous discussion...
Aloft, a ridge builds from the north-central United States to
the Great Lakes and vicinity, including our CWA, through
tonight before exiting toward the Northeast United States and
vicinity on Friday. At the surface, the ridge continues to
affect our region as the embedded high pressure center moves
from Lower MI to the southern Appalachians. This will allow a
moisture-starved warm front to sweep NE'ward through our CWA on
Friday. Fair weather is expected to persist through Friday as
stabilizing subsidence accompanies the aforementioned ridge.

Mainly clear sky, weak or calm surface winds, and low humidity
at/near the surface are expected to allow efficient nocturnal
cooling to occur this evening through about daybreak Friday
morning. However, around daybreak, a slight increase in what
will be a S'erly synoptic MSLP gradient at that point will allow
a light SW'erly breeze to develop across our CWA and transport
somewhat warmer air into our area. Lows primarily in the lower
to mid 30's and areas of frost formation are expected in
interior NW PA and northern OH toward daybreak, where a Frost
Advisory is in effect from 12 AM to 9 AM EDT Friday morning.
Elsewhere, lows are expected to reach mainly the upper 30's to
mid 40's. Localized river valley steam fog is possible in
interior NW PA and northern OH around daybreak. Any fog will
dissipate by mid-morning, following the onset of diurnal
convective mixing of the boundary layer. Daytime heating and
low-level WAA along the northwestern flank of the surface ridge
are expected to allow Friday's late afternoon highs to reach
the mid 60's to lower 70's in NW PA, the upper 60's to mid 70's
in NE OH, and mainly the mid to upper 70's farther west.

WNW'erly flow aloft and embedded shortwave disturbances are
expected to impact the Lake Erie region and Upper OH Valley
Friday night. At the surface, the ridge exits generally S'ward
as a cold front settles S'ward through our region. Current odds
favor a dry cold front passage due to limited low-level
moisture along and ahead of the front. Abundant cloud cover,
especially in the mid/upper-levels and associated with moist
isentropic ascent along the upper-reaches of the cold front and
ahead of the shortwave trough axes, will contribute to a milder
night Friday night. Lows are expected to reach mainly the upper
40's to mid 50's around daybreak Saturday.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
On Saturday, a cold front is expected to sag south across the area,
ultimately stalling somewhere south of the lakeshore. General upper
level support and moisture continues to remain fairly limited with
this initial frontal passage, but opted to maintain 20-30% PoPs
across much of the area through the early afternoon hours. Later in
the day, a weak shortwave will progress east, enhancing the lift and
increasing the potential of showers Saturday evening into the
overnight hours. In addition, a surface low over the Midwest will
move along the aforementioned boundary towards the central Great
Lakes Saturday night. This low pressure will deepen over the area on
Sunday as an stronger upper level trough pushes south across the
region. With increased moisture, frontogenesis, and overall upper
level support, widespread showers are expected on Sunday and a few
rumbles of thunder cannot be ruled out. Although the low pressure
will quickly depart to the east, the shower potential will linger
across the central and eastern counties into Monday. There remains a
bit of model divergence in how much the low will deepen and how
quickly the low will move to the east. If the low speeds up a bit,
areas of NEOH and NWPA could see a transition from synoptic  to lake
enhanced showers earlier, but right now those mechanisms look to
become dominant more on Monday.

Highs on Saturday and Sunday will climb into the mid to upper 60s,
possible scraping 70 degrees across the southwestern tier of
counties. Overnight lows on Saturday will remain mild in the low to
mid 50s in many places, with the exception of NWPA that may dip into
the 40s. Sunday night will be notably cooler as the cold front moves
east, dropping lows into the upper 30s in NWPA to the low 40s
elsewhere.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
An upper level trough is expected to persist across the Eastern
United States through at least mid-week as a surface low continues
to meander northeast towards Nova Scotia. This will result in a
sustained north-northwest flow across across the eastern Great
Lakes. This flow will usher in the coolest airmass the area has seen
this fall with 850mb temperatures falling to -1 to -3C. This will
allow for a period from Monday through Tuesday night of the
potential for lake effect showers across NEOH and NWPA. Current
model guidance suggests lake induced instability ranging from 1000-
1500 J/kg with equilibrium levels exceeding 20kft. Temperatures
should remain warm enough for all showers to be primarily rain,
although cannot rule out a few flakes flying in NW PA. Showers
should dissipate by Wednesday afternoon as high pressure and a drier
airmass become established across the area. These dry conditions
should persist through the end of the period.

High temperatures will be much cooler this period with highs likely
lingering in the 50s with overnight lows dropping into the 30s.
Temperatures will be a few degrees warmer closest to the
lakeshore.

&&

.AVIATION /00Z Friday THROUGH Tuesday/...
VFR continues through the TAF period as high pressure remains
overhead. Winds will continue to diminish this evening and
become light and variable overnight tonight. Winds increase
Friday morning becoming southwesterly at 10-12 knots after 14Z.

Outlook...Periodic and scattered rain showers with non-VFR
expected this Saturday through Tuesday.

&&

.MARINE...
High pressure will persist across the area keeping winds across the
lake light and variable into Friday morning. As the high departs to
the east on Friday, winds on the back side will increase from the
southwest to 15-25 knots by the afternoon as a cold front gradually
approaches from the west. This will result in a period of Small
Craft Advisory conditions by Friday evening and persisting into
early Saturday. By Saturday morning, a cold front will sag south of
the lakeshore allowing winds to shift to northerly at 10-20 knots
through mid-morning. Winds will become easterly at 5-10 knots by
Saturday afternoon and persist into Sunday.

A low pressure system will move northeast across the region on
Sunday, moving a cold front east and allowing winds to again
increase from the northwest to 15-25 knots. This will result in
waves building to 4-6 feet through Monday night. This will likely be
another period that a Small Craft Advisory will be needed. As the
parent low continues to drift northeast away from the area and high
pressure builds in, winds will weaken on Tuesday to be 10-20 knots
into Wednesday.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Frost Advisory until 9 AM EDT Friday for OHZ010-013-014-
     020>023-029>033-036>038-047.
PA...Frost Advisory until 9 AM EDT Friday for PAZ002-003.
MARINE...None.

&&

$$

SYNOPSIS...Iverson
NEAR TERM...Iverson/Jaszka
SHORT TERM...Campbell
LONG TERM...Campbell
AVIATION...Iverson
MARINE...Campbell

Source: CLE issues Area Forecast Discussion (AFD) at Oct 10, 9:15 PM EDT

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