Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 241426
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1026 AM EDT Thu May 24 2018

.UPDATE...
Issued at 1026 AM EDT Thu May 24 2018

Morning composite analysis reveals our incoming upper level ridge
axis knocking on the door, stretching up through Wisconsin and
across far western Lake Superior into Canada. Large area of
surface high pressure remains centered across the Great Lakes and
stretches to the Gulf Coast, with dry weather continuing for much
(but not all) of Michigan.

More humid (and modestly unstable) air is just upstream across
the lake, along and west of the upper ridge axis with surface
dewpoints pushing into the 60s. Pseudo warm front arcs from the
northern plains down through Minnesota and Iowa. Batch of showers
and a few thunderstorms are ongoing north of the warm front
rolling from NE Minnesota into western upper Michigan.

Rest of today will be largely quiet, warm and relatively dry
with some cloud cover spilling into the region from the west.
Ongoing showers/storms in the WUP should diminish as they head
east into the more stable environment. But of course I will keep
an eye on any decaying showers that may try and sneak into
eastern upper later in the day. Will also need to keep an eye on
any convective development across Wisconsin later in the day along
the eastern edge of the instability axis, with any decaying
showers that could also try to sneak into our area later this
evening.

&&

.NEAR TERM...(Today through Tonight)
Issued at 319 AM EDT Thu May 24 2018

Impactful weather: Areas of fog into daybreak in and around the nrn
portions of Lakes Michigan and Huron. Maybe a rumble of thunder in
eastern upper late tonight.

Pattern synopsis and forecast:

Sfc high pressure and a core of dry air was shifting into the
eastern Great Lakes early this morning, while mid level ridging and
warming temperatures were pressing into the western Great Lakes.
Gradually increasing sfc dew points over cold Lake Michigan has
continued to result in marine stratus and fog, and weak SW flow was
feeding this through the Straits and over into far nrn Lake Huron
now. Otherwise, only some thin high level cirrus was crossing the
region. All of the action remained out west of us, within/ahead of a
shortwave trough working into the nrn and cntrl plains. Low pressure
associated with this wave was in western ND/SD, and a channel of
deeper moisture was feeding from the gulf, northward through a warm
front extending from the low, down through Iowa and the low/mid
Mississippi valley. Pockets of showers and thunderstorms were dotted
across the central conus, as well as in the upper Mississippi
valley, within stronger low level winds and steeper lapse rates
aloft.

The mid level ridging does get suppressed to some degree as the
aforementioned shortwave works itself eastward into the western
Great Lakes tonight. The warmer air mass will be noticed through the
day as temperatures climb even higher than yesterday`s warm
readings. Highs today are expected to top out in the 80s for most of
nrn Michigan, with much cooler readings in coastal areas, mainly in
Lake Michigan, but also through the Straits region. The marine fog
and stratus is expected to continue into daybreak, expanding into
far nrn Lake Huron and lingering into a good chunk of the day. The
warmer air arriving from the west however, ought to eat away at any
stratus/fog through morning. This will result in most all areas
seeing a warm and mostly sunny day.

The sfc low pressure will lift into srn Canada tonight, with the
warm front pressing into the far western Great Lakes. Moisture
increases to over 1.00" PWAT with slowly steepening lapse rates
aloft, but there will be an expected lack of a decent LLJ and even
weaker upper level forcing. Regardless, we are slowly trying to get
primed for the development of showers and quite possibly a rumble of
thunder. This will be a slight chance at best for late tonight, and
more so across eastern upper Michigan, in the path of weak ejected
vorticity from the shortwave. A milder night with lows in the middle
50s to around 60F for most areas, cooler near the Great Lakes.

&&

.SHORT TERM...(Friday through Saturday)
Issued at 319 AM EDT Thu May 24 2018

...Unsettled weather Friday and the weekend...

High Impact Weather Potential: Scattered thunderstorms possible both
Friday and Saturday.

Pattern Forecast: Upper level ridging across the eastern half of the
CONUS early this morning will continue right through the beginning
of the forecast period on Friday before gradually becoming dampened
by a shortwave expected to ride along the western periphery of the
ridge...crossing northern Michigan Friday night into Saturday.
Strong surface high pressure will also gradually shift eastward with
occasionally unsettled weather becoming the result through the
upcoming holiday weekend.

Primary Forecast Concerns/Challenges: PoPs & thunder chances Friday
through Saturday.

Increasingly strong/deep southwesterly flow during the day Friday
will continue to aid in both moisture and warm air advection across
the region locally. Friday`s high temperatures progged to range from
the mid-upper 70s across the far north to the low-upper 80s south of
the bridge. Would not be surprised to see a few 90+ degree readings
across downsloping areas of northeast lower. Friday`s scattered
precip potential will likely remain focused across eastern upper and
eventually across far northwest lower by the late afternoon/
evening...all associated with pockets of deeper moisture (PWs
greater than 1.5") and better mid level forcing ahead of the
aforementioned shortwave. Developing instability (upwards of several
hundred J/kg of MLCAPE) is expected by the afternoon hours, which
continues to support scattered thunderstorms, although as the prior
shift mentioned...rather anemic wind fields aloft and bulk shear
values less than 20 kts are less than supportive for any organized
severe weather.

Occasionally unsettled weather continues Friday night into Saturday
with PoPs littering that portion of the forecast. It certainly won`t
be a complete washout for the many holiday weekend activities going
on across northern Michigan, but partly to mostly cloudy skies and
occasional showers/thunderstorms certainly seem likely. Guidance
remains fairly bullish with respect to increasing instability by
Saturday afternoon as MLCAPE values are progged to range from 750-
1,250 J/kg across much of the forecast area (skeptical of this due
to more cloud cover). With slightly stronger bulk shear anticipated,
especially west of I-75, it`s not out of the realm of possibilities
that a stronger storm or two is able to develop, but given this is
still 72+ hours away, it warrants keeping an eye on as we near the
holiday weekend. Saturday`s high temperatures remain warm...varying
from the 70s across eastern upper to the low-mid 80s for many inland
spots across northern lower.

.LONG TERM...(Saturday night through Wednesday)
Issued at 319 AM EDT Thu May 24 2018

High Impact Weather Potential: Chance of thunderstorms continues
Saturday night through Sunday.

Unsettled weather is expected to continue at times right on through
the end of the weekend before Canadian high pressure gradually sags
into the region from the north Monday through the middle of next
week...likely bringing a return to dry (but still warm) weather.
High temperatures through the period ranging from the mid 70s to low
80s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 556 AM EDT Thu May 24 2018

...VFR...

High pressure and dry air will slowly move east of the region
today into tonight. The marine fog/stratus has largely eroded and
VFR will be the rule. Sfc winds will be more S/SW and generally
under 10kts. Only a few higher based cumulus expected this
afternoon, along with some thin high cirrus. A bit more upper
level moisture expected tonight for PLN/APN. No rain chances
foreseen for the airports, but maybe a roaming shower late
tonight around PLN.

LLWS expected to develop late tonight as the pressure gradient
tightens up ahead of approaching low pressure and warm front into
the far western Great Lakes.


&&

.MARINE...
Issued at 319 AM EDT Thu May 24 2018

High pressure and the recent weak pressure gradient will work east
of the nearshore waters today and into tonight, ahead of approaching
low pressure and warm front that may bring some low end advisory
level gusts in Lake Michigan for Friday afternoon. This is a low
chance of occurring at this point, as it also appears to be just a
quick window of opportunity, plus conditions will be quite stable
over the Lakes. Chances for showers and maybe even a rumble of
thunder start late tonight, and increase Friday with various other
chances over the weekend as the low pressure and warm front linger
in the area.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&

$$

UPDATE...BA
NEAR TERM...SMD
SHORT TERM...MG
LONG TERM...MG
AVIATION...SMD
MARINE...SMD


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