541
FXUS63 KMQT 141854
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
254 PM EDT Wed Aug 14 2024

.KEY MESSAGES...

- Light rain showers possible over the north central this
  afternoon via the lake breeze.

- Low pressure system to bring showers and thunderstorms
  Thursday through early Saturday.

- Generally more dry pattern for the back part of the weekend
  and beyond, though minor disturbances may bring the occasional
  shower.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 140 PM EDT Wed Aug 14 2024

Upper air pattern consists of a 500 mb trough off the west coast and
a ridge over the Mississippi River valley and a trough over the
eastern U.S. A shortwave over the northern Rockies will get
organized over the northern plains by 12z Thu. Will continue with
some slight chance pops for this afternoon for lake breeze
convergence showers as there is some signal that a few could develop
along the boundaries. Otherwise, did not make too many changes to
the going forecast and kept pcpn chances out until really late
tonight in the far west as next system approaches.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 253 PM EDT Wed Aug 14 2024

The weather for the remainder of the week will be driven by a 500mb
trough centered over the Dakotas by 12Z Thursday. The resulting
surface low will be around 1005mb over the Dakotas/MN border
Thursday morning, and isentropic ascent ahead of the low will bring
showers to the MI/WI state line Thursday morning per HREF guidance.
While a soaking rainfall is expected, flooding should not be a
concern given the dry pattern the past few weeks. Virtually all
of western Upper Michigan has had 50% or less of the normal
precipitation for the past 30 days, with the eastern half being
around normal to slightly below normal. HREF mean 6-hourly QPF
rates are a quarter inch to a half inch with this system.
Temperatures around 70 Thursday will lead to not much surface
instability until late, so thunder will be unlikely until the
late evening hours, and with only around 10 kt of 0-6km shear to
work with, thunderstorms will be too disorganized to be severe.
Showers continue through Friday as the center of the low
pressure passes close to the UP. PWAT values approaching 1.5
inches on Friday are up to a half inch above normal for this
time of year, so some heavy downpours are to be expected with
the stronger storms, but with cloud cover keeping temperatures
from breaking much above the lower 70s, surface instability will
be somewhat lacking and 6-hourly QPF rates will only be around
a quarter inch broadly on Friday per LREF guidance.

The last 24 hours of guidance have somewhat slowed the departure of
showers in the east as the pattern which once had three distinct
troughs over the US/Canada border will become more broad as ridging
builds over the central CONUS. While this does support slowing the
movement of the trough to the east, it will also mean a surface high
of around 1020mb will build over the Upper Great Lakes by the end of
the weekend, ushering in a more dry period. Ensembles greatly vary
on exact solutions into next week, but the general pattern of
northwesterly flow is one that is often subject to the shortwaves
that rotate around the central CONUS ridge, which means that there
will be at least some slight chances (15-25%) of precipitation in
the forecast through the middle of next week, though the impacts of
said precip chances will be lesser.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1219 PM EDT Wed Aug 14 2024

VFR conditions dominate through tonight as high pressure ridging
slowly gives way to an incoming shortwave low currently over the
Northern Plains. Rain will move into IWD towards the end of the
forecast period with conditions dropping to MVFR.

&&

.MARINE...
Issued at 253 PM EDT Wed Aug 14 2024

Wind gusts will remain below 20 kt through Thursday morning. By
Thursday afternoon, a low pressure system will approach the Upper
Great Lakes, causing easterly and southeasterly wind gusts to around
25 kt Thursday afternoon through Friday morning. Wind gusts will
fall to around 20 kt as winds become northerly with the low pressure
passing to the south of Upper Michigan. The arrival of high pressure
by the end of the weekend will result in wind gusts below 20 kt
Saturday evening through the remainder of the forecast. During the
period of easterlies late Thursday into Friday, waves will pick up
to 4-6 feet.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...07
LONG TERM...GS
AVIATION...07
MARINE...GS