Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 211704

Area Forecast Discussion
National Weather Service Gaylord MI
104 PM EDT Fri Jul 21 2017

Issued at 1056 AM EDT Fri Jul 21 2017

Narrow ridge of high pressure extends from Western Ontario thru
Michigan late this morning. Meanwhile...low pressure continues to
develop over the Northern Plains...with an associated warm front
extending from the low thru Iowa southeastward into the Ohio
Valley. Area of convection continues to fire just ahead of the
surface low and north of the warm front...with additional
convection moving thru Ohio. Closer to home...skies remain mostly
clear across our entire CWA attm...although mid/upper level
clouds from upstream convection will begin to spread from west to
east into our area this afternoon as the warm front lifts toward
the Western Great Lakes region. Still expect no precip for our
area this afternoon...with any chances of precip holding off until
later this evening. Expect another warm day for the Northwoods...
as afternoon highs warm well into the 80s.


.NEAR TERM...(Today through Tonight)
Issued at 323 AM EDT Fri Jul 21 2017

...Warm today before rain chances return tonight...

High impact weather potential...locally dense early-morning fog.
Chance for non-severe t-storms tonight.

A weak ridge of high pressure extends from ne MN to sw lower MI.
Quiet wx and mainly clear skies are the result, though we are seeing
some fog form in spots. The quiet wx should hold thru this evening.
However, extended stretches of dry wx haven`t really been our
thing this summer, and that won`t be changing. Return flow west of
the ridge is contributing to MCS development in the northern
plains, down toward Iowa and northern IL. That sort of activity
may start to impact northern MI tonight.

Today...darkening seen in early morning fog imagery suggests some
fog patches over northern lower MI are relatively thick. That
said, July sun will make short work of them regardless. Anticipate
fog will dissipate by 10-11am, with plenty of sunshine for the
rest of the day. Some cu will get going, especially along the
inland- moving lake breeze boundaries. Moisture pooling along
those boundaries will push MlCape values up to 200-300j/kg. Could
we cook something off this afternoon? It`s not impossible, as
there isn`t much of a cap. But suspect we will mix out BL moisture
a bit more than the Nam thinks. Can`t really find a CAM that
produces any precip this afternoon, and even the Nam itself is dry
here. Will stick with that. Evolving upstream MCSs will push as
far east as western or even central WI, but return flow and
instability is non- existent further east. A late-day increase in
cirrus is likely, but otherwise no impact into early evening.

A warm day ahead. Max temps near 80 in eastern upper, mainly in the
80s in northern lower MI (70s on some of the beaches, while a stray
90f or two in northern lower isn`t out of the question). will the upstream MCS(s) take a run at us? Surface
ridge will move to the eastern lakes, allowing return flow to amp up
into northern MI (especially overnight). Low pressure will move from
eastern SD to the Iowa/WI border area, and once again the warm front
will not get further north than far southern lower MI. MCS
development will of course be favored north of the front. An initial
e to ese motion is expected, but eventually a veering LLJ and
growing surface cold pool will turn things to the right. That`s also
here all the instability is; in this state, south of I-96 (perhaps
/well/ south). So, per SPC, primary MCS track will be to our sw
(again). Might perhaps be grazed by a stronger elevated in the sw,
depending on how things play out, but overall this looks doubtful.
Marginal risk area from SPC just clips the MBL area; will not
mention a svr threat in the morning HWO.

Given the above, and given trends in recent events, am reluctant to
push pops too terribly high. Likely pops may still be order for MBL-
CAD, but not as far north as TVC/Gladwin, with pops decaying further
as you continue north. Interesting that, eerily similar to how
things went last night, the Nam sprouts some very late-night
convection over far ne lower MI, separate from the main action. A
convectively-induced shortwave or two may help that along. So will
expand the mention of showers/t-storms a bit further north, into at
least parts of eastern upper MI. Timing: recent trends support
staying on the faster side of guidance. A chance of showers/t-storms
could reach sw sections by mid/late evening, increasing and
expanding from there.

Mild min temps; from the upper 50s near Whitefish Bay to some upper
60s in the far south.


.SHORT TERM...(Saturday through Sunday)
Issued at 323 AM EDT Fri Jul 21 2017

...Thunderstorms over the weekend...

High Impact Weather Potential...Thunderstorms marginally severe
along and south of M-55 Saturday.

Pattern Synopsis/Forecast...Seems we have been getting our share of
sfc lows moving in from the Upper Mississippi Valley and into our
area with the warm front moving north during the day. This again
looks to be the case on Saturday so will expect that there will be
thunderstorm chances. However, they don`t look severe except maybe
along the M-55 corridor. A 500 mb shortwave moves into the Upper
Great Lakes Saturday night, and may contribute more during the
evening, but as we move away from the heat of the day, will expect
that the overnight will be rain showers. Sunday, as we get the
diurnal heating and the 500 mb low moves over the forecast area,
will expect that thunder will again break out, but probably not
severe, as the sfc will have cold advection from the cold front
moving through the region behind the sfc low. High pressure then
builds into the region overnight.

Primary Forecast concerns...The track of the sfc low will mark where
there will be severe weather. If the sfc low moves to the north we
could get into the warm sector and then it is possible that the
chances for severe weather will go up. If it goes south, then it may
even take our thunderstorm chances. It seems to be a low confidence
track forecast.

.LONG TERM...(Sunday night through Thursday)
Issued at 323 AM EDT Fri Jul 21 2017

...Dry to start the week...

High Impact Weather Potential...None.

Extended (Monday through Thursday)...Monday and Tuesday look dry as
high pressure builds into the region. Temperatures at this point
look to be below normal for Monday as the cooler air following
Sunday`s cold front move into the region. Tuesday looks more to be
around normal with the mid to upper 70s and even around 80.
Wednesday, the next front moves into the region which could kick off
more showers, and possibly thunderstorms, depending which model you
believe. Thursday could include some thunderstorms if the GFS is
right, then it would dry out overnight. The ECMWF on Thursday has it
dry all day and is hinting that it would be dry to start the weekend
as well.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 100 PM EDT Fri Jul 21 2017

VFR conditions will continue thru the TAF forecast period despite
increasing/thickening/lowering cloud cover over the next 24 hours.
Chances of precip will increase as well ahead of low pressure
developing over the Northern Plains. Thunder is possible late
tonight into Saturday...but will handle with VCTS for MBL and TVC
for now. Winds will remain mostly light/variable.


Issued at 323 AM EDT Fri Jul 21 2017

High pressure will cross MI today, resulting in light winds and
onshore lake breezes. Low pressure will pass to our south on
Saturday, resulting in developing east winds. These will pick up
late tonight in Saturday, and not out of the question for some
locales (like the ne lower MI coast) to approach small craft
advisory wind/waves.




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