Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 190358
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1158 PM EDT Sat Aug 18 2018

.UPDATE...
Issued at 930 PM EDT Sat Aug 18 2018

Convection got a late start (thanks to strong heating being
delayed by stratus), but our initial showers did indeed develop
shortly after 5 pm. Presently, a few showers linger from GLR to
CAD. Have tweaked to expand and extend mention of showers, but per
CAMs everything should be gone by midnight.

Stratus never exited parts of the se (Iosco Co in particular),
though it is still shrinking. Stratocu is expanding over n
central lower MI. With weak sub-850mb winds veering from ne to e
to se, clouds will expand back into much of northern lower MI,
especially overnight. Cloud cover will be most extensive south of
M-68 and east of M-37. Fog is a possibility as well, especially
outside the cloudier locales.

&&

.NEAR TERM...(Through Tonight)
Issued at 309 PM EDT Sat Aug 18 2018

...A few Showers/Thunder Possible Into the Evening...

High Impact Weather Potential: Minimal. Thunderstorms, perhaps
this afternoon. Non-severe.

Pattern Synopsis/Forecast: Mid level ridging continues to
build into the upper Midwest/western Great Lakes, along with
surface high pressure building down out of Ontario into the
northern lakes region. Pesky stratus that developed before
sunrise across northern lower MI, expanding through the morning
hours, has finally eroded back across a good portion of the
region, although there is still a good amount of cloudy skies
across NE lower MI. I expect the remaining stratus to continue
shrinking through the rest of the afternoon and this evening.

Tonight: First, still waiting to see if any convection will fire.
18Z SPC mesoanalysis reveals under 500 J/KG of MLCAPE across
northern lower Michigan, greatest south of M-55, along with some
capping aloft and CINH. We may not see much more if SPC forecasts
are correct (based on 40KM RAP data). Satellite imagery does show
show congested CU across the SW/W part of northern lower Michigan,
which has some potential. But nothing on radar yet. Plan to keep
at least chance PoPs across inland parts of northern lower
Michigan heading into the evening, primarily where the congested
CU is located and along the "edge" of eroding stratus deck. But
given the meager instability and capping, think I will keep shower
chances to less than 40 percent. Thunder may not happen at all.
Will see...

Later tonight: Low level flow will veer more southeasterly in
time. This suggests "residual" low level moisture across NE lower
MI into Lake Huron may get advected back up into northern lower
Michigan, offering the potential for more expanding stratus late
overnight and through the morning hours. Have bumped up sky cover
forecasts accordingly (and that still might not be enough) along
with patchy to areas of fog.

&&

.SHORT TERM...(Sunday through Tuesday)
Issued at 309 PM EDT Sat Aug 18 2018

Sunday through Monday

...Dry Sunday, Rain Begins Monday Night...

High Impact Weather Potential...Thunderstorms Monday night.

Pattern Synopsis/Forecast...High pressure continues over the region
will continue to keep the region dry, for the most part, on Sunday.
However, as the models have continued to do, afternoon showers and
thunderstorms look to be a possibility. With this sort of "ring of
fire" dirty ridge, not surprised that with the moisture in the lower
levels, that with a little heat and the boundary collisions on the
radar, and things take off. This looks to be the case again for
Sunday, although as we have seen during the past few days, the bulk
of the forecast area won`t see anything. Sunday night, any showers
will diminish quickly as the 700-500 mb dry layer looks to help cap
off the convection. The 500 mb ridge over the region, then begins to
break down. By 15z/Mon, showers will be possible as the cold front
and 500 mb trough approach the state, having started to cross W Lake
Superior and the Upper Mississippi River. Models have been going
with the idea, the last several runs, that the main part of the
showers and thunderstorms will start Monday evening and progress
across the state through the night, evolving into a stratiform rain
event by Tuesday morning.

Primary Forecast Concerns...So far, the timing on the models has
held steady with a few showers expected to break out in the
afternoon, but the bulk of the rain and thunder to be in the evening
and overnight as the cold front moves through the state. Dynamics
don`t look that great, as the 500 mb winds barely get to 30 knots as
the front moves into the forecast area and with the timing being
after sunset, the instability isn`t all that strong, so won`t expect
any severe threat with these.

.LONG TERM...(Tuesday night through Saturday)
Issued at 309 PM EDT Sat Aug 18 2018

...Rain Tuesday then Pretty Much Dry through Saturday...

Extended (Tuesday through Saturday)...The ECMWF shows a decent band
of rain on the north side of the sfc low in a deformation zone
producing some rain, possibly heavy at times, as the system move NE
through the state. The GFS has moved its focus south of the forecast
area and doesn`t put as much of the heavy rain into the forecast
area, unlike the ECMWF. With that agree with the WPC idea that most
of N Lower is in a marginal threat for excessive rain. Not really
expecting flooding, but probably a decent relief from the D1 drought
that has been going on. Wednesday through Friday are dry from high
pressure building back into the region. Temperatures start around
normal and continue slowly above normal into the weekend. Expecting
scattered rain on Saturday/Saturday night as another cold front
moves into the forecast area. Not sure about how well the models
will do with this, but with this Monday night/Tuesday storm, maybe
we have see a pattern change?

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1157 PM EDT Sat Aug 18 2018

Fog/stratus will return to at least ne lower MI tonight.

Some stratus still lingers in the OSC area, while higher stratocu
and some fog is found in patches in the rest of northern lower MI.
Anticipate another night of expanding low clouds, with APN again
likely to get the worst of it. This should be a little faster to
burn off on Sunday. Showers again possible in the interior Sunday
afternoon, inland from the TAF sites, so no problems there.

Light/variable winds.

&&

.MARINE...
Issued at 309 PM EDT Sat Aug 18 2018

Winds and waves remain on the lighter side. Persistent N/NE flow
may result in some better waves along the Lake Huron nearshore
areas into this evening. Winds veer southeast overnight and south
for Sunday and beyond, but remain 10 knots or less through the
period. No marine headlines anticipated.


&&

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

$$

UPDATE...JZ
NEAR TERM...BA
SHORT TERM...JL
LONG TERM...JL
AVIATION...JZ
MARINE...BA


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