248
FXUS63 KAPX 170007
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
807 PM EDT Mon Jun 16 2025

.KEY MESSAGES...

- Showers tonight...spotty at first but increasing chances overnight.

- Shower/thunderstorm chances Tuesday...possible stronger storms.

- Heavy rainfall threat Wednesday?

- First significant heat of the summer early next week?

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 347 PM EDT Mon Jun 16 2025

Pattern Synopsis/Forecast: Large scale pattern features broadly
zonal flow across the northern tier of states...downstream of a
trough axis off the west coast.  Broad ridge over the southwestern
U.S./southern Plains with an elongated trough axis moving into the
lower Mississippi Valley.  A couple of short wave troughs within the
northern tier zonal flow...one crossing Lower Michigan this
afternoon showing up nicely in water vapor imagery...a second better
defined wave (and perhaps convectively enhanced) over the Dakotas/
Nebraska.  Also a remnant MCV over southeast Wisconsin.  Visible
imagery also hints at a southeastward propagating gravity wave over
northern Ontario and extending back into northern Lower.  There is a
fair bit of humidity working its way back into the upper Great Lakes
this afternoon.  At the surface...ridge of high pressure extends
west from New England into the Great Lakes...with a weakly organized
area of low pressure over the northern Plains/upper Midwest.  Small
stub of a warm front lies across South Dakota/Iowa...with a poorly
defined boundary along the Ohio River.  Farther to the north an east-
west oriented front runs across far northern Ontario into Manitoba.

Northern Plains short wave trough is forecast to cross Lake
Superior/Upper Michigan during the first half of Tuesday...along
with a compact surface reflection (already 2-3mb/3h pressure falls
across the eastern Dakotas coincident with a 1006mb low center).
While the surface low is expected to propagate away from Lake
Superior...it will drag a weakening cold front across Michigan
Tuesday afternoon.

Primary Forecast Concerns:

Showers late afternoon/early evening: Passing gravity wave front
kicked off some scattered showers as is passed through fairly
quickly during the late morning/early afternoon across eastern Upper
and the Straits region.   Cu field has been bubbling up across
northwest Lower...instability as expected is pretty thin at just a
few hundred J/kg.  So remains to be seen whether short wave trough
emerging out over Lake Michigan can kick off any showers...or will
subsidence behind gravity wave squash any minimal potential (as
would be suggested by mid cloud clearing in its wake).  But moisture
will continue to increase from the west this evening ahead of the
approaching surface low that is expected to be over central Lake
Superior by Tuesday morning with its trailing cold front back across
eastern Wisconsin. Would expect remnants of convection over the
upper Mississippi Valley this afternoon to get pushed into northern
Michigan overnight...in addition to any scattered convection that
develops ahead of it along advancing moisture axis.

Shower/thunderstorm chances Tuesday...possible stronger storms:
Would expect rain to be ongoing Tuesday morning especially east
of the US-131 corridor. Cold front arrives during the afternoon
and with it a decent axis of instability (likely > 1000J/kg
MLCAPE). If this comes to fruition could be some sneaky stronger
storms with the front and will mention this possibility in the
afternoon Hazardous Weather Outlook despite only being in the
General SPC Day 2 outlook.

&&

.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
Issued at 347 PM EDT Mon Jun 16 2025

Days 2-3 (Wednesday-Thursday): Tuesday`s cold front looks like it
will stall across southern Michigan...along which a frontal wave
will ripple northeast and across Lower Michigan probably Wednesday
night.  Exactly how the surface pattern will evolve is a bit unknown
as model latent heat release is likely playing around with the model
surface pressure pattern.  But a good bit of moisture in play along
and north of this front...along with potentially favorable jet
dynamics is setting up the possibility for heavy rainfall across the
forecast area for Wednesday and especially Wednesday night. Rainfall
amounts of 1-2+ inches could be in play for some areas depending on
how the details set up.  But something else to add to the afternoon
HWO (most of Michigan in the Marginal WPC Day 3 Excessive Rainfall
Outlook).

Days 4-5 (Friday-Saturday):  Drying trend for Friday as 594+DM 500mb
ridge expands eastward across the Mississippi Valley and into the
southeastern U.S..  Northward moving frontal boundary associated
with this warmer air mass expected to push across the upper Lakes
Saturday and will likely bring another round of showers/
thunderstorms with it.

Days 6-7 Outlook (Sunday-Monday): CPC 6-10 Day outlook looking
pretty toasty as 594DM heights build into northern Michigan (a +2 to
+3 sigma 500mb standardized height anomaly).  As long as we are far
enough south of potential MCS "ridge runners" which is always our
bugaboo for much hyped heat events...the first round of 90+ degree
heat is certainly in play heading into next week.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 800 PM EDT Mon Jun 16 2025

Low level winds increase tonight, enough to flirt with LLWS for
most locations. Sfc winds may increase as well though, and thus
uncertain of extent. WS remains at TVC as a result as winds at
about 2kft approach 35 to 40 kts. Otherwise, potential broken
line of -SHRA/-TSRA approaches from the west, with some
uncertainty of southern extent. Went with PROB30s as a result
for most locations along the Lake Michigan shoreline. Best
probability will likely be for KCIU, timing for this activity
generally 10 to 18Z. Winds increase after sunrise, with 10G20KT
during the daytime hours. Brief MVFR possible for KCIU, and to a
lesser extent KPLN during the morning to midday hours.

&&

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

&&

$$

SHORT TERM...JPB
LONG TERM...JPB
AVIATION...JLD