Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 211933
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
333 PM EDT Sat Oct 21 2017

.NEAR TERM...(Tonight through Sunday)
Issued at 333 PM EDT Sat Oct 21 2017

...Summer`s last stand...

High impact weather potential...elevated fire danger into early
evening, as well as in ne lower MI Sunday afternoon.

Deep southerly flow continues, well ahead of a cold front advancing
across western MN/IA. Mid/high clouds continue in northern MI
(with thinning in sw sections), but no cu, and surface dew points
have again mixed out into the 30s in a few locales. Wx thru
tonight will be mostly quiet, but showers will make a push into
the region Sunday, along with the associated cold front.

Any real low-level moisture is found pretty close to the incoming
cold front. Even though surface dew points are climbing into the 50s
in WI, the se half of the state has effectively no cloud cover. That
isn`t stopping elevated showers from popping along a moisture
gradient and vort ribbon aloft, from the STL area up to almost BEH.
This axis of elevated convection increasingly fades to virga with
northward extent. It`s going to difficult for this to generate
precip this far north; Nam tries to spit out a few showers, toward
and especially after 06z. Am not inclined to bite on this (the
RAP is dry, at least for that part of the area).

Pre-frontal moisture band does edge toward western sections very
late tonight. The Rap is occasionally spitting our some showers
ahead of the front, some of which impact the northern Lake MI
islands, and western Mack Co. A slight chance for a shower might be
justified here after 6am.

Min temps tonight in the 50s to near 60f, coolest in the interior of
ne lower MI, warmest along the Lake MI coast.

Much better rain chances arrive Sunday from w to e, with the cold
front across eastern upper and making inroads into nw lower MI
during the afternoon/early evening. Height falls aloft are subtle,
but present in the afternoon, especially in nw sections. The most
widespread precip is likely to be along and just behind the boundary
as it moves in. Chance pops warranted in nw lower and eastern upper
MI thru early afternoon. Likely to categorical pops push as far east
as Rogers/Mio/Gladwin by early evening, with only chance pops thru
00z/8 pm east of there. Rainfall amounts of a quarter-inch or so are
expected in the west half of the forecast area. We might be able to
muster 200-300j/kg of MuCape in northern lower MI. If coupled with
stronger forcing, would be comfortable mentioning isolated thunder.
But we don`t really have that, and will omit any thunder mention for
now.

Max temps Sunday mainly in the 70s (some upper 60s near Lake MI).
Another day of elevated fire danger in ne lower MI, with warm temps
and gusty winds ahead of incoming precip. However, RH levels will
be higher than today.

&&

.SHORT TERM...(Sunday night through Tuesday)
Issued at 333 PM EDT Sat Oct 21 2017

...The Gales of Late October...

High Impact Weather Potential...Gusty winds winds on Tuesday and
Tuesday night.

Pattern Synopsis/Forecast...The cold front is part way through the
forecast area at 00z/Mon and looks to take the next 12 hours to move
through the rest of it. However, The ECMWF looks to slow down a bit,
as the 500 mb trough digs in behind the front. Another piece of
energy then digs into the 500 mb trough and begins to close off the
trough into a closed low, on the ECMWF. The GFS is a little slower
doing this overnight, so that by 12z/Tue the 500 mb closed low is
somewhere over the Upper Great Lakes. The sfc low then deepens and
moves to the N-NE, but at different speeds. This will affect the
winds, as the ECMWF will be much windier behind the low than the
GFS. We are looking at Gales over the Lakes either way, but the
ECMWF could be showing gustier winds. Will wait on the next run or
so to figure which way the models are going with this.

Primary Forecast concerns...We can use a good soaker again, and
while we will get a decent amount of rain, but think that it will be
below the 2.5" in 6 hours that we would need for flooding. The other
issue of concern, as alluded to in the previous section, is the
forecast low track. If the ECMWF is right, it could end up quite
windy with gusts to 40 mph so possibly some sort of wind headline.
The GFS has moved the center of the low out, well north of the Upper
Great Lakes, and the resultant gradient will support low end gales
on the lakes, but probably not wind headlines on the land. So will
have to watch the direction of the models.

&&

.LONG TERM...(Tuesday night through Saturday)
Issued at 333 PM EDT Sat Oct 21 2017

...Cooling off, but Continued at or Above Normal...

Extended (Tuesday night through Saturday)...The pattern definitely
looks to be flipping back to a fall like pattern with the usual
strong wind storms that usually move through the Great Lakes this
time of year. This also opens up the possibility of mixed
precipitation, mainly at night and at interior, higher elevation
locations, as we get close to the end of October. Tuesday night we
start off in the midst of the first 500 mb closed low of days 4-7.
It looks to try to lift out on Wednesday, only for a piece of energy
to move into the back side of the low and retrograde it a bit before
exiting and allowing the trough to lift out of the Upper Great Lakes
by 12z/Thu. This will definitely cool us down and bring periods of
rain through the Wednesday night. Expect a brief dry period for
Thursday before the next bowling ball of cold air and rain moves
into the region for Friday and Saturday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 140 PM EDT Sat Oct 21 2017

LLWS again tonight. VFR, except becoming MVFR at MBL Sunday
morning.

Warm southerly breezes will continue, though a cold front will be
advancing across Lake MI Sunday afternoon. Low levels will remain
on the dry side thru much of the forecast, and VFR conditions will
largely prevail. Exception is at MBL toward midday Sunday, when
lower cigs just ahead of the front will impose MVFR conditions.
Threat for showers will wait until just beyond this forecast
period.

S to ssw surface winds will be gusty at times into this evening,
and again on Sunday.

&&

.MARINE...
Issued at 333 PM EDT Sat Oct 21 2017

Breezy southerly winds continue thru Sunday morning. A sharp cold
front will slowly push into northern MI Sunday afternoon and
night, with nw winds behind it. This front will also bring
widespread showers beginning Sunday afternoon.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...SMALL CRAFT ADVISORY until 6 PM EDT Sunday for LMZ323-341-342-
     344>346.
LS...NONE.
&&

$$

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


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