000
FXUS63 KAPX 110345
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1145 PM EDT Wed Apr 10 2024

.KEY MESSAGES...

- Widespread soaking rain and gusty winds expected Thursday and
  Friday.

- Quiet weather for the majority of the long term. Temperatures
  warm again to the upper 60s this weekend.

&&

.UPDATE...
Issued at 957 PM EDT Wed Apr 10 2024
Complex area of low pressure continues to develop over the
Lower Mississippi Valley late this evening...and is starting to
make a move northeastward into the Ohio Valley. Northern edge of
the deep moisture and resulting precip shield associated with
this system has reached portions of SE Lower Michigan...and will
continue to make slow northward progress thru the overnight
hours. Latest near term models have delayed the arrival of this
rain shield into our CWA by a few hours...and have made the
necessary adjustments to overnight and Thursday morning POPs
accordingly. Still certainly expect the development of
widespread rain across our entire CWA from SE to NW Thursday
into Thursday night. In the meantime...clouds will continue to
gradually increase/thicken/lower ahead of this precip. Expect a
relatively mild night across our Northwoods with overnight lows
falling mainly into the 40s.

&&

.NEAR TERM /THROUGH TONIGHT/...
Pattern Synopsis/Forecast: Nearly zonal mid-upper level flow across
northern Michigan this afternoon, sandwiched between upper-level low
pressure working north toward James/Hudson Bays and deep troughing
continuing to dig over the nation`s midsection. The latter will be
the focus Thursday into Friday, but with little in the way of
sensible weather prior to that as higher surface pressures remain
overhead locally.

Forecast Details: Main focus through the remainder of the daylight
hours continues to revolve around elevated fire danger given
temperatures well into the 60s, RHs falling to the 20-30% range over
many inland locales and occasional breezy west winds with gusts as
high as about 20 mph or so.

Otherwise, a vigorous cu field should dissipate with the loss of
daytime heating, but be replaced by increasing mid-high cloud this
evening through the overnight. While rain chances will increase very
late tonight near the M-55 corridor, the vast majority of wet
weather is expected to hold off until the daytime hours on Thursday
(discussed below).

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
Pattern Synopsis / Forecast: Current look at water vapor imagery
shows what looms for the Northwoods, as a stout shortwave over east
Texas drums up a firehose of moisture from the Gulf and depositing
it over the Louisiana to Florida corridor via robust convective
episodes along a weak stalled stationary boundary slowly lifting
through the Deep South. While this is occurring, a northern stream
wave is slowly digging through the Dakotas at this time. Over the
next 24-48 hours, the Texas wave (and associated surface low
pressure) lifts north and east along a stationary front roughly
spanning from Toronto to Dallas, drawing ample theta-e advection
northward into the Ohio Valley and Great Lakes. While this occurs,
the wave over the Dakotas will dig south and east, and a phasing
process is set to commence, resulting in considerable deepening of
the surface low as it moves from Indiana / Ohio into SE Michigan /
SW Ontario before potentially retrograding into Lake Huron Friday.
Result will be increasingly steady periods of rain building
Thursday, continuing into Friday. In addition, deepening low
pressure will pinch the pressure gradient, drumming up strong
surface flow to accompany this rain. As this is all happening, a
ridging response in the Plains will amplify as another Pacific wave
digs into California, thus leading to a rather timely departure of
the moisture and rainfall for the start of the weekend as high
pressure returns to the Great Lakes.

Primary Forecast Concerns:

Rain Timing / Amounts: Rain will be spreading northward Thursday
morning, though most places may actually start the day dry. That
probably doesn`t last long, especially near Saginaw Bay as showers
and steadier rain begins to spill into the region with the low
drawing closer. Those of you in the eastern U.P. may be able to
squeak out much of the morning dry, but the afternoon looks wet.
Steadiest / heaviest rains set to occur Thursday into Thursday night
before the system begins to depart Friday into Friday evening. As
mentioned by the previous forecaster, this system will have quite
the considerable amount of juice with it owing to a direct Gulf
connection... still looking at near or slightly above the 90th
percentile of mid April climatological PWATs associated with this
system, so some of this rain could come down at a noticeably more
intense rate at times.

As such, QPF estimates for Thursday - Friday generally range between
1.00" to locally 3.00"+ pending on which guidance you pick. Where
that locally heavier strip of rain lands will be dependent on how
strong the system gets and the exact track it takes. All in all,
looking at probabilistic guidance, probabilities to see appreciable
rainfall are quite high for most. Probs of 1.00"+ of rain stand at 85-
95% east of US 131, and 65-85% elsewhere. In terms of 2.00"+ probs,
those stand at 50-70% east of US 131 and 30-50% elsewhere. Even
3.00"+ probs are on the board, though sit at 5-15% roughly along a
Cadillac to Rogers City line. All in all, certainly looks like a
soggy stretch. In regard to flooding potential, WPC has placed most
of Michigan in a Marginal Risk (level 1/4) to see flash flooding. At
this juncture, sandy soils and a relatively dry winter probably
mitigate flash flooding considering the duration of the event, and
if any does manage to occur, it will probably be limited to poor
draining areas (particularly urban spots).

Wind: As the system becomes closed off and deepens considerably, a
pinched pressure gradient will induce stronger sustained winds and
gusts. Sustained winds of 15-25kts will be possible at times... and
probabilistic guidance puts mean wind gusts anywhere from 40-45kts
(strongest at the Lake Huron shore and near Grand Traverse Bay)
Friday into Friday evening. This could result in some scattered
power outages, especially considering this strongest wind will occur
following the majority of the rainfall associated with the system,
which could lead to some weakened tree root structure (i.e, uprooted
tree risk). As for the marine effects, gales are looking likely
later Thursday and especially Friday.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Weak wave passes through early Sunday, which could bring about some
showers to the region, but given northern stream origins, this could
be more nuisance than not. In addition, timing of this feature
(early morning) may give way to a drier conclusion to Sunday. High
pressure quickly builds into the Great Lakes on the heels of this
system, with temperatures likely holding in the 50s and 60s (colder
in immediate shores) amid drier conditions as we head into the new
work week. Guidance is trying to bring in another wave closer to
midweek, and that could bring another round of showers... though
still plenty of time to figure the specifics out and muddle through
spreads in guidance.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Deep low pressure will continue to lift out of the Lower
Mississippi Valley overnight and into the Ohio Valley by
Thursday morning...and will then continue northward into the
Southern and Eastern Great Lakes Thursday afternoon and night.
Widespread rain will develop across most of Michigan along the
northern and western side of this system...impacting our area
mainly Thursday afternoon and night. VFR conditions overnight
will drop to MVFR Thursday afternoon as this widespread rain
shield develops from SE to NW across our area. Mainly
light/variable surface winds overnight will become E/NE on
Thursday and will strengthen to 15 to 25 kts.

&&

.MARINE...
East-northeast winds begin to increase late tonight into Thursday
with widespread Small Craft Advisory conditions becoming likely.
Winds turn northwesterly by Thursday night with gusts likely
increasing to gale force by late Thursday night through much of
Friday. Some low probabilities (<10%) for storm force winds,
primarily on Lake Huron, during this time frame.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Gale Watch from Friday morning through late Friday night for
     LHZ345>347.
     Gale Watch from Friday morning through Saturday morning for
     LHZ348-349.
     Gale Watch from Thursday evening through Friday evening for
     LMZ323-341-342-344>346.
     Gale Watch from Friday morning through late Friday night for
     LSZ321-322.

&&

$$

UPDATE...MLR
NEAR TERM...MJG
SHORT TERM...HAD
LONG TERM...HAD
AVIATION...MLR
MARINE...MJG