945
FXUS63 KAPX 301415
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1015 AM 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.

&&

.UPDATE...
Issued at 953 AM EDT Sun Jun 30 2024

Satellite is depicting clouds clearing from the north as high
pressure and drier air continues to build in. Surface
observations are showing current dew points in the 40s across
the state, while 24 hour surface temperatures difference shows
this morning is around 10 to 20 degrees cooler than yesterday.
Clouds are starting to thin and lift over land and will continue
to do into the early afternoon hours.

&&

.SHORT TERM /THROUGH TONIGHT/...
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 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 /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 631 AM EDT Sun Jun 30 2024

MVFR cigs will hold this morning, with cool/moist air now very
much in place. Some -DZ is also occurring, primarily over the
interior of northern lower MI, but also perhaps at CIU.
Conditions will improve late morning thru the afternoon, with
all sites becoming VFR. Will keep it VFR tonight, but there may
be some fog potential late, especially MBL/PLN.

Nw winds gust to around 20kt today, becoming light tonight.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through 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.

&&

$$

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