000
FXUS63 KAPX 120133
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
933 PM EDT Thu Apr 11 2024

.KEY MESSAGES...

- Widespread soaking rain tonight into Friday.

- Strong gusty winds late tonight through Friday.

- Next chance of rain Saturday night into Sunday morning.

&&

.UPDATE...
Issued at 933 PM EDT Thu Apr 11 2024

990mb surface low is over central Lk Erie, moving ne, and
deepening. The low will reach near southern Georgian Bay by
morning. Rain covers most of northern MI, though the rain is not
widespread in eastern upper MI (ANJ has seen relatively little
so far this evening). Heavier rain rates are (as expected) in ne
lower MI, and the highest QPF is still forecast there thru
morning. Precip coverage will be lesser in far western areas
overnight.

APN has already seen a 36mph gust this evening. Gustier winds
will become more common as the pressure gradient tightens.

&&

.NEAR TERM /UNTIL 8 AM THIS MORNING/...
Potent bit of PV punching through the Upper Midwest this afternoon,
located over western WI/eastern IA. Further east...a surface low
continues to track NNE into SE Lower MI...with a surface boundary
stretching from NW OH toward Port Huron as of 18z. Winds beginning
to strengthen across central Lower in response...and backing from E
to NE. Nice axis of deformation stretching from the Keweenaw down
into central WI along far edge of cloud shield and PV strand.
Increasing difluence over the region and continued saturation of the
atmosphere...with most areas now seeing at least light
rain/drizzle...though a few areas, especially along the Sunrise
Coast, seeing higher returns on radar (and likely some enhancement
of rain with continued fgen aloft). Perhaps even some indication of
gravity waves in current radar.

Expecting surface low to continue to deepen and track NNE into SW
Ontario tonight. Expecting deformation axis north of the low to hang
over the region from NNE-SSW tonight and become the focus for
persistent rainfall through the night, particularly along and east
of I-75 in NE Lower...though still can`t rule out a secondary axis
of heavier precip along and west of I-75 this evening. Winds
expected to become NNW to NW toward morning...and dramatically
strengthen prior to daybreak.

PRIMARY FORECAST CONCERNS:

Rain tonight...signals still look good for heavier rainfall. KAPN
has picked up 0.06 inches in the last hour with that better band of
reflectivity moving overhead...and would not be surprised to see
better hourly rates than this over that way, particularly if that
band persists...and think it should, given abundant forcing aloft.
Do still think a widespread 0.5-1.0" of rain is most likely for the
overnight, not including the continued rain into Friday
morning...though think there is a shot at closer to 1-2" of rain,
particularly across the Tip of the Mitt and Presque Isle county,
perhaps toward Boyne/Mancelona, where there is better potential for
the deformation axis to stall out and linger the more focused
lift/rainfall longer...though less certainty in how far south this
heavier rainfall axis will extend...and if the better deformation
does end up a little further west than anticipated, the TVC area
(already somewhat notorious for localized flooding) could end up
more in the 1-2" range than currently expected...and would not be
surprised in that case to see flooding concerns, though for now, not
expecting any widespread flooding concerns given the recent dry
weather and relatively sandy soil overall (save for the much more
fertile Saginaw Bay region)...in addition to longer duration of
rainfall that should allow for better drainage of surface water into
the soil.

Strengthening winds late tonight...tightening pressure gradient late
tonight will lead to rapid strengthening of winds. Signals point
strongly toward sustained winds of 20-30kts by daybreak,
particularly over NE Lower MI and along the coasts where lack of
friction over the water should further enhance winds.
Additionally...strong LLJ develops aloft tonight into Friday
morning...with 850-925mb winds ramping up around 40-50+kts shortly
before daybreak. Guidance soundings suggest the boundary layer
should remain favorable for mixing down some of these better gusts,
even prior to daybreak...though the bulk of the strongest winds
should hold off till 12z and later.

&&

.SHORT TERM /8 AM THIS MORNING THROUGH SUNDAY/...
Pattern Synopsis / Forecast: Robust area of troughing associated
with deepened surface low departing to the east of Lake Huron will
be forced eastward with time through the day Friday and into Friday
night as ridging across the Plains amplifies and intrudes into the
Great Lakes. This will result in a pinched pressure gradient as the
low moves east and surface high pressure arrives in its wake. Rain
will gradually erode from the region through the day Friday, and as
drier air builds into the region, cloud cover will become less
prevalent, particularly west of I-75. This should boost mixing
tendencies with a strong 850mb wind max over the Great Lakes,
resulting in strong gusts at the surface Friday into Friday evening.
As high pressure moves through, the pressure gradient will slacken
some, resulting in lesser flow at the surface. As more of a
progressive flow builds, a quick moving disturbance will introduce
the next chance of rain Saturday night into Sunday morning, largely
clearing the region by Sunday afternoon. Temperatures set to be in
the 40s Friday, warming some into the 50s away from the big lakes
Saturday, and mid 50s in the eastern Yoop / near lakeshores Sunday,
with inland locations of northern lower likely punching well into
the 60s.

Primary Forecast Concerns:

Friday Winds: Aforementioned pressure gradient will be pinched right
over the Great Lakes for much of the day Friday. 850mb winds are
going to be racing, potentially to the order of 55-60kts pending on
which member of guidance one prefers. Considering the drying aloft
and low level lapse rates steepening with diurnal heating, mixing
some of the flow aloft to the surface is going to be possible. We
will likely be able to mix rather consistently from 925mb, which is
progged to have 35-45kt flow, which would be enough to garner a Wind
Advisory for the CWA. Winds will be strongest along the immediate
lakeshores, particularly in Cheboygan, Presque Isle, and Alpena
counties along the Lake Huron shore. One thing to consider in this
setup is that guidance has been trying to hint at a little bit of a
clearing trend from west to east during the day Friday. In the event
that this occurs (or worse, overachieves) and we go more of a partly
sunny regime, mixing will become more aggressive, and we may be
running the potential for bringing down winds from higher than just
925mb. Winds should be on a downward trend as we progress through
the overnight hours. For now, will be placing the CWA under a Wind
Advisory, in effect from 12z Friday - 06z Saturday owing to the
potential for 45-50mph gusts.

Friday Rain Showers: Scattered showers will continue to grace us
with their presence through the morning hours Friday, particularly
east of US 131 in northern lower and I-75 in the eastern Yoop. As
far as additional rainfall goes, not a ton more in the making,
probably an additional 0.10 - 0.25", particularly closer to Lake
Huron one goes. Drier air should erode lingering precipitation
across NW lower and closer to Whitefish Point in the eastern Yoop.
Rain showers likely clear Lake Huron by 18-21z, leaving the
remainder of the day dry.

Saturday night - Sunday: Weak wave will zip through the region
Saturday night into Sunday as progressive flow sets in place across
the region. As of now, the Plains origin and quick motion of the
system will lead to a moisture depleted setup in the low levels,
but modest lapse rates aloft may be conducive for some convective
shower activity to build into the region, particularly south of M-
72. Even then, the chances of this occurring are rather low.
Elsewhere, more of a synoptic rain is anticipated, and even this
looks suspect given the dryness of the low levels. Pretty ho-hum,
nuisance precipitation that probably drags its feet into Sunday
morning before clearing out by midday as warmer temperatures are
drawn into the region by more of a southerly flow regime.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
High pressure set to be in place Monday, with pleasant temperatures
in the 60s away from the big lakes... honestly wouldn`t be surprised
to see spots inland leap into the 70s with high pressure more or
less right overhead, which could mitigate warming along the shores
given a solid lake breeze setup. Looking ahead, another wave ejects
east of the Rockies and will make its way into the mid Mississippi
Valley Tuesday. Lingering influences from high pressure probably
keeps things drier here, but one thing this feature will do is
rocket some very mild air into the region as a southeast flow regime
is generated. This system is set to close off to our west, and while
some guidance is trying to drum up showers and thunder across the
region Tuesday, it wouldn`t be of much surprise if the day winds up
drier with highs in the 60s and 70s if the system trends slower (as
closed lows do). This system WILL have to make its way through at
some point, and that for now looks like the Wednesday timeframe,
drawing in a slightly cooler airmass on its heels after midweek.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Worsening conditions tonight. Very windy Friday.

Low pressure will strengthen east of MI tonight/Friday.
Associated rain will continue tonight, and become somewhat
heavier. Vsbys/cigs will lower, and IFR conditions will
eventually become widespread, if not tonight then on Fri
morning. Precip will diminish on Fri, and cigs/vsbys improve
later in the day.

Winds will increase from the north tonight. Nw-nnw winds Friday
will gust to circa 40kt at times by afternoon.

&&

.MARINE...
Winds tonight turn NNW and strengthen dramatically as a low pressure
system moves by to our east and strengthens. Gale force winds
expected on the lakes/nearshores by 9-12z Friday...and expected to
hang on into Friday evening/night for our Lake Huron nearshores.
Some potential for scattered storm force gusts at times Friday
afternoon, particularly toward Presque Isle light and down toward
Alpena...though confidence is much stronger in winds of 35-45kts.
Winds expected to become more west to southwesterly and gradually
weaken going into Saturday night.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...Wind Advisory from 8 AM Friday to 2 AM EDT Saturday for
     MIZ016>018-020>036-041-042-086>088-095>099.
MARINE...Gale Warning from 5 AM Friday to 5 AM EDT Saturday for LHZ345-
     346-349.
     Gale Warning from 5 AM Friday to 10 AM EDT Saturday for LHZ347-
     348.
     Gale Warning from 5 AM to 11 PM EDT Friday for LMZ323-341-342-
     344>346.
     Gale Warning from 5 AM Friday to 2 AM EDT Saturday for LSZ321-
     322.

&&

$$

UPDATE...JZ
NEAR TERM...FEF
SHORT TERM...HAD
LONG TERM...HAD
AVIATION...JZ
MARINE...FEF