418
FXUS63 KAPX 160150
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
950 PM EDT Thu Aug 15 2024

.KEY MESSAGES...

- Shower and thunderstorm chances increase tonight.

- Muggy and unsettled wx continues thru this weekend.

&&

.UPDATE...
Issued at 942 PM EDT Thu Aug 15 2024

Isentropic upglide helping to produce an area of light rain
currently sliding east/northeast across northern Michigan. The
rain has been slow to move east, limited by the ambient dry
atmosphere. But saturation is slowly occurring and the rain
should spread across the remainder of northern lower over the
next several hours. A few thunderstorms possible overnight,
especially west of I-75 in northern Lower, as mid level lapse
rates steepen and we develop some elevated skinny CAPE.
Rainfall amounts overnight less than 0.50", with many areas
likely under 0.25". With surface dewpoints creeping up,
overnight lows will generally be held in the 60s.

Adjusted timing of precipitation and POPS in current forecast.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 323 PM EDT Thu Aug 15 2024

Pattern/synopsis: High pressure extends from NY to NC, moving
east. 1004mb occluded low pressure is over nw MN, with a closed
500mb low very slightly trailing. These systems become
vertically stacked tonight, and move east to northern WI/western
upper MI on Friday.

Forecast: Initial band of showers (now over ne WI and southern
Lake MI) will push into nw lower MI this evening. Rain
overspreads eastern upper, n central and ne lower MI after
midnight tonight. Most of this will not have thunder associated
with it. Overnight, as somewhat cooler temps arrive aloft, and
moisture increases in the low levels, some skinny MuCape
develops, especially in western areas. A few thunderstorms will
be possible, especially in nw lower MI. Rainfall totals of
around 0.50" will be common tonight, away from ne lower MI.

On Friday, that initial shower band will exit eastern and
northern areas in the morning. The most prominent dry slotting
will stay upstream in WI until almost evening, when it pushes
into nw lower MI. Models have struggled with precip/cloud
coverage on Friday, with inconsistent signals as to where we
destabilize. The bulk of the models suggest a cloudier/grungier
day, less in the way of sunshine, and much less in the way of
SbCape returning. Destabilization is more likely in
central/southern WI then here (though activity that develops
there could take a run at our southern areas, especially Fri
evening). We have enough moisture, instability, and forcing to
support sct/nmrs showers/storms, especially early and again late
in the day. Progged instability (500-700j/kg) and deep shear
(0-6km bulk shear 20-25kt) are insufficient for much of a severe
threat. If we see more sun than planned, severe storms could
enter the equation again. But SPC has removed most of northern
lower MI from a severe threat, leaving in roughly M-55 and south
only.

Lows tonight on the warm side, mid 60s for most. Highs Friday in
the 70s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 323 PM EDT Thu Aug 15 2024

Pattern Synopsis and Forecast:

The well advertised upper level low currently evident on water vapor
imagery across the Dakotas will continue to make its way slowly
across the area this weekend. This is expected to result in
additional showers along with possible non-severe storms Friday
night into Saturday. Precipitable water values between 1.5 and 1.75
inches portends possible heavy downpours. It`s a bit uncertain on if
moisture/instability will linger into Sunday but it looks like there
will still be enough in place to develop scattered showers
(especially along and east of I-75). In addition, it will remain
rather muggy through Sunday. Northwest flow aloft then develops
early next week and holds through much of the work week. This will
advect in a much more comfortable drier airmass. Nixed the slight
chances for a few showers around mid-week due to model disagreement
over a possible trough traversing the flow (a majority of guidance
now weakens/wipes out this possible feature). Temperatures next week
are expected to be in typical mid-August ranges with highs in the
70s and lows ranging from the mid 40s to the mid 50s. Proceeding
that, lows will still be mainly in the sticky low and mid 60s for
both Friday and Saturday nights.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 706 PM EDT Thu Aug 15 2024

Lowering Cigs Overnight

VFR at all terminals early this evening but conditions will
gradually deteriorate tonight as rain slowly pushes e/ne across
the area. All sites will become MVFR to high end IFR late
tonight into Friday morning. Some embedded TSRA possible late
tonight. Still question marks as to how much drier air will work
into the area on Friday. If things do clear out in some areas,
it could result in the development of a few stronger TSRA.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

UPDATE...JK
SHORT TERM...JZ
LONG TERM...AJS
AVIATION...JK