158
FXUS63 KAPX 101729
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
129 PM EDT Wed Jul 10 2024

.KEY MESSAGES...

- Moderate to heavy rain near Saginaw Bay into this evening.
  Locally heavy rain elsewhere in northern MI this afternoon and
  evening.

- Warmer and more humid conditions this weekend into early next
  week.

&&

.UPDATE...
Issued at 1030 AM EDT Wed Jul 10 2024

Broad troughing over the eastern US...with a niblet digging into the
Upper Midwest...as remnants of Beryl continue to trek northeastward
through the OH Valley/Great Lakes region. Primary punch of PV
lifting through central Lower MI attm...with some convective
activity developing over NW Lower MI on the cusp of the dry slot
amid greatest convective instability along deformation axis. We do
have some instability over the area attm...with even about a hundred
j/kg of MUCape on the morning sounding here. Low-level northeasterly
flow out of Canada making it a little more tricky for deeper
moisture to make it to the surface compared to the much more
saturated profiles downstate, and do see a pretty tight moisture
gradient stretching SW-NE across northern Michigan...but where
better mesoscale deformation bands have attempted to focus, have
received a quick quarter inch of rain in the last few hours (e.g.,
KAPN has recorded 0.28 inches as of 13z). Expecting tropical
moisture to continue to hang around, given continued southwesterly
flow off the Gulf; though better/deeper moisture may end up to our
east at this point, still think we will end up under a deformation
precip axis here in the Upper Great Lakes. This moisture, combined
with good forcing from a dynamic system...think we will still have a
shot at some sneakily better rainfall totals this morning and beyond
particularly where deformation bands end up hanging on
longest...and/or wherever convective-type activity sets up and
hangs out. Current QPF forecast is more or less just a general
idea to highlight where highest totals /should/ be focused...but
will not be surprised if these numbers are too low in some
cases.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 336 AM EDT Wed Jul 10 2024

Pattern/Synopsis: 1003 mb surface low, the remains of TC Beryl,
is very near IND. The low will move ne, passing near DTW this
afternoon, before heading for Lk Ontario and weakening tonight.
Associated upper trof will be over northern MI late this
afternoon.

Forecast: Light rain is expanding into southern areas, with
perhaps moderate rain pushing into Gladwin/Arenac Cos. But
hourly precip rates from MOP/MBS and other places just to our
south are unimpressive thus far. Antecedent dry air below 600mb
is still taking a toll on precip expansion and intensity. Which,
this early, was expected. With the infusion of some tropical
characteristics to the airmass, rainfall rates will push
higher. An evolving deep warm layer (wet bulb zero heights as
high as 13k ft) and high moisture (PWATs nearing 1.75") are
indicative of this. Overall, though, progged QPF continues to
look manageable in the far se; 1.00-1.50" in parts of
Gladwin/Arenac/Iosco Cos. And to date, no observed data is
screaming that those amounts look too low.

That`s not the only source of locally heavy rain today. Though
cloud cover will be extensive, some diurnal heating will occur
thru it, outside of the expanding precip shield. Weak, skinny
MlCape (up to 300 j/kg) is progged to develop this afternoon,
roughly north of a line from MBL to APN. Relatively light
northerly flow in this area (winds will be stronger near Saginaw
Bay) will result in some lake-induced convergence, into parts
of northern lower MI in particular. CAMs are consistently
arguing for deep convection to form along the edge of the
precip shield this afternoon and evening, in parts of nw and far
n central lower MI, perhaps into far eastern upper MI. Pops/QPF
have been boosted here. Note that this scenario happened
yesterday, with flooding rains downstate in the afternoon in the
LAN area and along I-94, before the synoptic precip shield
pushed in. Don`t know that flooding is anticipated here, given
our sandier soil and more rural nature. But wouldn`t completely
rule it out either, given this anomalous airmass. The isolated
and speculative nature of this threat precludes a watch.

Best pops this morning remain south of a CAD-APN line. These
expand across much of northern MI this afternoon and early
evening.

Tonight, precip will diminish and end from w to e. Some local
downpours remain possible this evening. Partial clearing works
in w of I-75, mainly overnight.

High temps today mainly 70s, though OSC/Tawas won`t budge much
from the current upper 60s. Warmest today in eastern upper MI.
Lows upper 50s to lower 60s.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 336 AM EDT Wed Jul 10 2024

Pattern Forecast: Quieter but warmer and more humid conditions are
expected during the long term for the most part. Heights slowly
build through early next week. A cold front eventually ushers in
cooler temperatures for the middle of next week.

Forecast Details: Moisture from the remnants of Beryl is expected to
continue to push off to the east of the region Thursday. However,
lingering troughing aloft in combination with instability from
heating of the day (MUCAPES of perhaps a few hundred J/Kg), could
spark isolated afternoon showers and possible storms for both
Thursday and Friday afternoons. This looks to be mainly confined to
areas closer to Saginaw Bay. The trough then gradually fills with
higher heights aloft still expected this weekend. However, guidance
still shows periodic weak upper level disturbances propagating
through the flow. Therefore can not rule out a few showers or storms
from time to time (especially Sunday and early next week). Steadily
warming temperatures as well as increasing humidity levels each day
through at least Monday. Highs cresting well into the 80s with a few
spots perhaps touching 90 for Saturday through Monday. Extended
guidance is then in general agreement that a surface front
eventually moves across the region at some point Tuesday bringing
slightly cooler temperatures for mid-week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 129 PM EDT Wed Jul 10 2024

Expecting more pop-up showers/storms to develop from EUP down toward
MBL this afternoon...between 18z and 3z. (Lake breeze noted along
the US-131 corridor from KGRR to KTVC...will monitor this region for
development that could impact TVC/MBL taf sites.) Slow-moving cells
likely to move from NE to SW given N/NE low-level flow...if they
move much at all. (Winds above 2000-3000ft from the NW, 15-25kts.)
Rain to hang out over KAPN most of the afternoon/evening...and could
hang out longer into the night. Not impossible for some sites (such
as KAPN) to go IFR at times this afternoon with a few sub-1kft cloud
bases over that way...but primarily expecting MVFR to VFR conditions
otherwise this afternoon for the area. Watching fog/low-cigs
potential for tonight as winds go light, esp at APN, MBL where most
rain is likely to fall...with IFR likely and LIFR possible.
Currently expecting improvements through the morning Thursday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 AM EDT Thursday for LHZ349.

&&

$$

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