679
FXUS63 KAPX 301810
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
210 PM EDT Sun Jun 30 2024

.KEY MESSAGES...

- Unseasonably cool today and tonight. High swim risk today.

- Unsettled Tuesday/Wednesday with a heavy rainfall threat.

- Dry forecast trend continues for Fourth of July holiday.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 313 AM EDT Sun Jun 30 2024

Pattern/synopsis: Departing cold front is crossing the lower
lakes early this morning. A secondary front is over eastern
Superior, and north of Lk Huron. High pressure is over the
northern plains. The high will build toward the western lakes
today, and over our heads tonight. This will gradually minor out
the secondary boundary.

Forecast: Healthy amount of low-level moisture in the area,
resulting in abundant low clouds. Places near Saginaw Bay have
the most breaks in the cloud cover, but there are some smaller
holes elsewhere. Per surface obs and radar, we are scavenging
up some shallow precip...especially in the eastern UP, but also
at times in nw and n central lower MI. APX radar (and satellite)
very much has the look of an activated Lake MI, with wind-
parallel banding. With upstream air temps in the upper 40s, and
northern Lake MI water temps in the upper 50s, that is
reasonable. Well, it is the last day of June and thus entirely
/unreasonable/ for lake effect to be occurring, but what can you
do.

Moisture will continue to get shallower, as inversion heights
fall with the approaching high. Some drizzle or sprinkles
remain possible into perhaps mid-morning. Eastern upper MI
(with less of a lake contribution with colder Superior upstream)
should trend to partly sunny by late morning, and mostly sunny
by early afternoon. Clearing in northern lower MI will be a
little slower, but will progress from nw to se with time. Partly
sunny breaks out by early afternoon, and mostly sunny by late
afternoon. Mostly clear skies tonight, but with some patchy fog
potential, especially west of I-75 in both peninsulas.

Breezy nw winds with overlake instability will support increase
wave action on some beaches. A high swim risk will continue on
much of Lake MI and part of Lake Huron.

Highs ranging thru the 60s today; late June sun will be able to
do some work, even with cold advection and morning clouds. Lows
tonight mostly 40s; would not rule out upper 30s in interior
cold spots.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 313 AM EDT Sun Jun 30 2024

Pattern Forecast: Split long wave trough from Atlantic Canada down
into the Mid Atlantic to start the long term forecast cycle
Monday...with a short wave ridge encompassing the nation`s
midsection and troughing over the western states.  Ridge axis will
cross the Great Lakes and end up to the east on Tuesday as height
falls spread into the northern/ central Plains.  Short wave trough
and associated baroclinic zone expected to reach the upper Lakes
Wednesday...and linger across Michigan for the Fourth of July (i.e.,
jet axis overhead).  Passage of another short wave trough looking
probable to start next weekend.

1023mb surface high encompassing the northern/central Plains tonight
will build east over the next 36 hours and be centered over the
Great Lakes Monday...near 1028mb which is strong for the start of
July (99th percentile for surface pressure).  High moves toward the
eastern seaboard Tuesday along with the short wave ridge...allowing
southerly warm/moist return flow to set up into the upper Lakes.
Midweek height falls expected to push a cold front across Michigan
in the Wednesday time frame.  What remains of this boundary will
probably get hung up across the Ohio Valley for Thursday...perhaps
returning north as a warm front ahead of next short wave trough
Friday.

Primary Forecast Concerns:

Unsettled Tuesday/Wednesday with a heavy rainfall threat: Return
flow around departing anticyclone is expected to bring a substantial
push of moisture into the Midwest and Great Lakes for the Tuesday/
Wednesday time period...precipitable water values at or above 1.75".
Broad area of warm advection/isentropic ascent expected to spread
rain into areas west of I-75 Tuesday morning...then east during the
afternoon.  Best QPF potential looks to be Tuesday night/Wednesday
morning with moisture transport focused into northern Michigan ahead
of a cold front that is forecast to cross the area later Wednesday
(may see a drying trend across at least northern Lower during the
afternoon).  Marginal risk in the new Day 3 Excessive Rainfall
Outlook (12z Tuesday - 12z Wednesday) covers eastern Upper/northwest
Lower Michigan (no change from yesterday`s Day 4 outlook).
Probabilities of more than 1 inch of rainfall range generally from
10 to 30 percent. Will see how this trends once higher resolution
guidance gets into the mix (which won`t occur in earnest until the
12z Monday forecast cycle). But the potential is certainly worth
watching and mentioning in the Hazardous Weather Outlook.

Dry forecast trend continues for Fourth of July holiday:  Out of
what may be an unsettled week beyond Monday...the Fourth of July
holiday on Thursday still holding on to the dry forecast.  Cold
front that comes through Wednesday is expected to settle far enough
south to minimize precipitation probabilities.  So will continue the
optimistic trend of a dry/warm Fourth (high temperatures should be
pretty close to normal) with little wind.

Rain chances return for Friday: Another short wave trough and
associated surface reflection expected to impact the upper Lakes on
Friday...which will bring another round of showers and
thunderstorms.  This activity may linger into Saturday but that is
more uncertain.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 159 PM EDT Sun Jun 30 2024

Skies lifting and scattering to generally FEW-SCT at 020-040
over eastern upper and NW Lower terminals. MVFR cigs lingering
over NE lower terminals but should be VFR by 22Z. Winds N/NE
around 5 to 15kts with gusts up to 20kts. Winds will diminish
after 03Z to VRB05KTs. Light winds and cool temperatures will
lead to patchy radiational fog potential for a few sites. Most
likely sites to be impacted by HZ/FG will be KMBL/KTVC/KCIU
after 09Z. Shallow moisture should limit duration of impacts to
terminals. Chances are high for VFR by end of the period if
terminals see HZ/FG.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 11 PM EDT this evening for
     MIZ016-018-020-021-025-031-098-099.
MARINE...Small Craft Advisory until 8 PM EDT this evening for
     LHZ347>349.
     Small Craft Advisory until 5 PM EDT this afternoon for LMZ323-
     341-342-344>346.
     Small Craft Advisory until 8 PM EDT this evening for LSZ321.

&&

$$

SHORT TERM...JZ
LONG TERM...JPB
AVIATION...ELD