195
FXUS63 KAPX 231857
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
257 PM EDT Mon Sep 23 2024

.KEY MESSAGES...

- Rain returns Tuesday.

- Rain-free weather and above average temperatures expected
  through the second half of this week into this weekend.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 254 PM EDT Mon Sep 23 2024

PATTERN SYNOPSIS/FORECAST:

Surface high pressure still largely in control of our
weather...centered to our northeast over Ontario...as subtle
shortwave ridging slides through. PV max over the Mid MS Valley
continues to lift northeastward this afternoon...with attendant
cloud shield overspreading southern Lower south of approx M-20 as of
18z. Next PV maximum still well west of us over the Northern Plains.
Little to no cu left this afternoon as we`ve mixed out enough to tap
into dry layer aloft. Afternoon dewpoints down into the 40s
signaling another potentially chilly night where radiational cooling
can take place. Winds still north to northeast...though a weak
enough pressure gradient today that Lake Michigan lake breeze is
trying to form toward MBL.

Expecting cloud shield to continue to lift northeastward through the
afternoon/evening...though it may struggle as it interacts with the
dry air in place attm. Upstream energy expected to dig into the Mid
MS Valley tonight into Tuesday with the aid of 120+kt upper jet
snaking its way through the flow. Current expectation is for a low
pressure to develop along what remains of BCZ through the OH
Valley...and lift northeastward into southeast Lower MI tonight into
Tuesday...with attendant rain chances trying to spread into the area
late tonight. In the meantime...will expect another chilly night
with lows in the low to mid 40s in the colder locales. Potential for
fog development again tonight...and a dreary day Tuesday, especially
the further south you go.

Primary Forecast Concerns: Rain returns Tuesday...

Temps aloft still cool enough to maintain a meager lake
response...and suspect we`ll ultimately look for some lake-
induced/enhanced showers as moisture overspreads the area later
tonight into Tuesday morning. Primary focus for this will be across
NE Lower, downwind of Lake Huron...though not impossible a smidgen
could get into the EUP with enough of a southeasterly component to
the flow. Think seeder-feeder processes could enhance rainfall
totals over this way (NE Lower/Saginaw Bay region)...though not
expecting a ton of rainfall overall, particularly noting trends
starting to keep the deepest moisture just south and east of our
area as the low lifts northeastward Tuesday. Could again be looking
at potential for some kind of mesoscale-driven heavier precip band,
somewhat similar to yesterday, with some signals for a bit of a N-S
band to develop over Lake Michigan later in the day as the trough
axis aloft approaches. If this idea verifies...could be looking at
the bullseyes for better precip on either coast with less certainty
over the interior. Additionally...south and east trend with the
moisture does have me concerned that the northwest portions of the
CWA may not receive much at all, particularly if we end up with a
sharp northern/western edge to the precip shield (as pwat guidance
suggests). A few embedded rumbles of thunder possible with this
Tuesday afternoon, particularly toward Saginaw Bay closer to the
surface low itself...and perhaps where lake-induced energy could
give things a bit of a boost...but nothing dramatic expected by any
means, given the warm sector remaining to our southeast...and lack
of better flow aloft.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 254 PM EDT Mon Sep 23 2024

Pattern Synopsis:

Southern stream shortwave/jet max will continue to lift across the
southern Great Lakes into Wednesday as amplified troughing digs
sharply down the Midwest toward the Gulf Coast. Said trough looks to
get cut off from the main flow and pivot near the lower Mississippi
Valley through the remainder of the period. Meanwhile, ridging is
expected to encompass the Great Lakes through the weekend into early
next week. One complicating factor will be the impact soon-to-
be/expected Hurricane Helene will have on the pattern, and eventual
forecast for the Great Lakes later this weekend.

Forecast Details:

Rain-free weather and above average temperatures -- Light rain
showers are expected to be ongoing at the start of the period, and
will begin to work northeast of the area late Tuesday
night/Wednesday morning. This aside, rain-free weather is expected
across northern Michigan through the end of the week and into this
weekend. Aforementioned ridging will keep surface high pressure in
place, and with the cut-off low well to our south, little
appreciable forcing and lack of frontal passages will keep a similar
airmass in place for a several day stretch -- potentially through
the remainder of the forecast period. Thus, rain-free weather and
highs in the 70s are anticipated across northern Michigan through at
least Saturday. These highs combined with overnight temperatures in
the low 40s to low 50s for most will be around 5-10 degrees warmer
than average for late September. Rain chances may begin to work in
late in the weekend/early next week depending on the track of
expected Hurricane Helene, but confidence is currently low in any
additional rainfall across the area after Wednesday morning through
the remainder of the long term.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 117 PM EDT Mon Sep 23 2024

High pressure slipping by this afternoon into tonight. A disturbance
expected to lift northeastward tonight into Tuesday, returning
clouds and rain chances to the region. Expecting lake enhanced rain
showers to develop downwind of Lake Huron tonight, sometime around
4z at KAPN. More widespread rain moves in from south to north
Tuesday, impacting MBL and TVC toward the latter part of the TAF
period. Fog and low stratus expected to redevelop tonight, esp
toward morning...with general MVFR to IFR cigs (though possibly
lower than advertised if it remains clear/calm tonight); better
chance of LIFR toward MBL and TVC toward daybreak. Winds generally
easterly (onshore/lake breezes at KMBL and KTVC this afternoon,
though) with gusts 15-20kts...diminishing overnight but remaining
largely easterly overall with that disturbance to our
south/west.

&&

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

&&

$$

SHORT TERM...FEF
LONG TERM...DJC
AVIATION...FEF