Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 201029

Area Forecast Discussion
National Weather Service Gaylord MI
629 AM EDT Thu Jul 20 2017

Issued at 629 AM EDT Thu Jul 20 2017

Some re-jiggering of morning precip trends. Activity that was
upstream continues to slide ese, and appears increasingly likely
to completely miss us. Meanwhile, deep convection has fired in ne
lower MI, near and w of APN, as a small bubble of instability has
advected north between MCSs. This one axis of better instability
should exit by 9-10am.


.NEAR TERM...(Today through Tonight)
Issued at 325 AM EDT Thu Jul 20 2017

...Sct showers and maybe a t-storm southern sections this

High impact weather potential...stray, non-svr storms possible
this morning south of M-72.

Warm front extends along the MN/Iowa border to central WI and
southern lower MI. Initial svr MCS is falling apart in northern
Indiana. But deep convection continues to fire to our west in
parts of WI/MN, where extremely moist/unstable air south of front
(dew points in the 70s) is being advected toward and across it.
This will pose a risk for showers/storms, mainly in northern lower
MI, until a cold front now reaching western Superior crosses the
region during the day.

Today...all sorts of of warm/moist/unstable air just to our south,
but its running out of time and ways to come north. Too much
precip along the front to allow for a substantial northward push.
There`s the risk of a stray shower or two just about anywhere
early this morning (some showers are scraping by Chippewa Co to
the north, a few small cells are popping near Beaver Isl, etc
etc etc). Best precip threat will be in the south, on the
northern fringe of MCSs moving e to ese in the central/southern
lakes. There are storms on our latitude back toward the Twin
Cities, and it`s not completely out of the question for a t-storm
to make it here, especially between sunrise and noon. But that`s
looking less and less likely.

Precip threat should wrap up by 1 pm as cooler/drier air moves in.
Decreasing clouds for the rest of the day. With less precip and
somewhat less clouds than earlier forecast, have bumped up temps a
bit. Highs will be mainly in the upper 70s to mid 80s, cooler
along some beaches.

Tonight...high pressure will build ese from MN into northern MI,
keeping our departed frontal zone suppressed to our south. The
resumption of return flow in western sections of the corn belt
will resulting in increasing convection late in northern
Iowa/southern MN/sw WI. It will be a while longer before this
poses a substantial threat to us. Instead, we see mainly clear
skies. Think we see enough mixing this afternoon/early evening to
keep fog from being a major concern, but the usual fog-prone
valley locales will likely see some.

Min temps lower 50s to around 60f.


.SHORT TERM...(Friday through Saturday)
Issued at 325 AM EDT Thu Jul 20 2017

...Occasional shower and thunderstorm chances...

High Impact Weather Potential: Slight chance of thunderstorms late
Friday and Saturday.

Pattern Forecast: Well-advertised progressive zonal flow across the
northern states into southern Canada will feature little change
through Sunday. Several mid level perturbations rotating through the
midsection of the country will be the main driver to our local
weather at various points later Friday through Saturday.

Primary Forecast Concerns/Challenges: Temporal and spatial
resolution of any precipitation chances/MCS potential late
Friday through Saturday.

Details: Little in the way of concern to start the short term
forecast period as high pressure sits atop the Great Lakes Friday
morning. Another day with high temperatures a few degrees above
normal looks likely...ranging from near 80 across eastern Upper to
the low-mid 80s elsewhere.

The next threat for potential precip across a portion of northern
Michigan arrives as early as Friday night. Current trends (much like
the MCS that developed across MN/WI on Wednesday) suggest an MCS
developing across southern MN/WI Friday afternoon before quickly
sliding east-southeastward toward southern Lake Michigan. However,
there remain several pieces of guidance that attempt to bring that
feature into northern/central Michigan. Thus, uncertainty in the
actual development and convective trends leads to another lower than
desired confidence forecast. It`s likely that this feature will
track along the axis of deeper moisture and theta-e/instability
gradient, which is currently progged to be south of the forecast
area, so gut feeling is once again that the worst passes well to our
south. Definitely warrants monitoring in future outlooks as there
remains time for subtleties in the guidance to change over the next
48 hours.

Additional showers and thunderstorms remain possible across all of
northern Michigan later Saturday into Saturday evening as a much
more defined wave drops out of southern Ontario into the northern
Great Lakes, aiding to focus precip further north across the U.P.
into northern Lower. With MLCAPE values during this period progged
to range from 500-1,000 J/kg and formidable winds aloft expected to
continue, a conditional severe weather threat can`t be ruled out.
Will continue to go somewhat conservative with high temps Saturday,
but it wouldn`t take a whole lot of afternoon sun to surpass the
upper 70s-low 80s currently depicted across a bulk of the forecast

.LONG TERM...(Saturday night through Wednesday)
Issued at 325 AM EDT Thu Jul 20 2017

High impact weather potential: Additional scattered thunderstorms
possible Saturday night and Sunday.

Focus in the extended revolves around the Sunday night through
Monday timeframe. Well-defined mid level wave mentioned above
continues its east-southeastward progression across the Great Lakes
Sunday through Sunday night. Partly sunny skies, occasional showers
and a rumble of thunder will continue to be the rule to wrap up the
weekend, although there are certainly hints that plenty of dry time
will be mixed in as well. Canadian high pressure gradually ushers in
cooler/drier air Monday through Tuesday evident by high temperatures
expected to fall back below normal by a couple of degrees.


.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1200 AM EDT Thu Jul 20 2017

Quiet conditions continue into the overnight hours as high
pressure crosses the region. Much uncertainty still on what
transpires very late tonight into Thursday, with at least some
support for an area of showers and maybe some rumbles of thunder
to move across the airports. Trends appear to lead to lesser
chances for rainfall, but given the uncertainty, will still carry
VCSH in the 09Z to 15Z timeframe. May be looking at a relatively
brief period of MVFR CIGS in the morning. Mostly light winds
through this forecast, with a sfc trough crossing after the
possible rains, for a shift out of the W/WNW.

There is at least some potential for low end LLWS tonight as the
possible showers arrive. Not a strong enough signal to mention in
the forecast right now.


Issued at 325 AM EDT Thu Jul 20 2017

A cool front will go thru early today, with ongoing light
southerly breezes becoming w to nw later today. Light west breezes
Friday. Onshore lake breezes each afternoon. Winds/waves far below
advisory levels.




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