Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 202352

Area Forecast Discussion
National Weather Service Marquette MI
752 PM EDT Sun May 20 2018

.SHORT TERM...(This evening through Monday)
Issued at 346 PM EDT SUN MAY 20 2018

Water vapor imagery and RAP analysis show a split flow pattern over
the western CONUS with a wnw confluent flow aloft into the Upper
Great Lakes region and sfc high pressure dominating. Lake breezes
have kept conditions cooler this afternoon near the Great Lakes
shores (40s and lower 50s) while much farther inland under sunny
skies and deeper mixing temps have risen in the upper 60s/lower 70s
along the WI border.

Winds will diminish to calm/near calm tonight, setting the stage for
a chilly night as dry air mass (precipitable water as low as one-
quarter to one-third inch) aids radiational cooling potential. Will
continue to favored the lowest of available guidance, bias corrected
mos guidance and bias corrected CMC global which is normally a
superior performer on radiational cooling nights. Traditional
interior cold spots should fall into the upper 20s/around 30F.

Sfc high pressure will remain in control continuing the dry
conditions on Monday. With the center of the high moving east
southeast gradient winds will increase near 10 mph with gusts
reaching over 15 mph at times over the west half of the fcst area.
The winds combined with high temps reaching into the lower 70s and
minimum RHs lowering into the 20 to 25 percent range will contribute
to elevated fire weather concerns especially over the west half.
Shortwave lifting ne from the Central Plains could bring some mid-
high clouds into s central portions in the afternoon, although any
showers associated with this system should remain south on Monday.

.LONG TERM...(Monday night through Sunday)
Issued at 356 PM EDT SUN MAY 20 2018

The main weather concern through the middle of the week will be
elevated wildfire potential, especially inland from the Great Lakes
where dewpoints in the afternoon hours will drop into the 20s. A
thermal trough is expected to develop across the interior during the
afternoon hours as temperatures heat up into the 70s and lower 80s
across the interior and lake breezes dominate the low-level wind
fields. The development of this thermal trough inland of the Great
Lakes will be reinforced on Wednesday as a weakening, dry backdoor
cold front drops south. Compressional along this trough axis should
allow for another day with well-above normal temperatures on

Thursday through early parts of the Memorial Day Weekend will
become much more active weather wise with increasing chances for
showers and thunderstorms. As result temperatures will be a bit more
difficult to forecast based on how cloud cover and precipitation
evolve. With the main shortwave associated with this pattern change
lifting northeast from the southwest into the northern Plains, this
track will favor good moisture transport this far north as the Gulf
of Mexico is progged to be open for days in advance. As this axis of
low to mid-level moisture gets into Upper Michigan on Thursday, we
will start to see chance for showers and storms increase across the
west half of Upper Michigan. With this convection well removed from
the main upper-level forcing, thinking the primary area of concern
will be along lake breeze boundaries and the far eastern edge of the
warm front, associated with a developing surface low in the northern
Plains. On Friday and Saturday, the surface low will track towards
the Arrowhead of Minnesota and then drop south across Wisconsin.
This should allow the warm front to gradually lift north across
Upper Michigan and allow for better chances for showers and
thunderstorms on Friday in the vicinity of the frontal boundary, as
well as lake breeze boundaries. On Saturday, as the low pressure
system tracks just to our south, this will allow for additional
chances for showers and thunderstorms. Towards the tail end of the
weekend, as the surface low continues to track south of the area we
should see a cool down, but lingering showers are not out of the
question. Right now it is difficult to say whether or not we will
see any strong to severe storms during this time period. However,
with a weakening, yet still impressive elevated mixed layer progged
to track across the region on Friday, this would favor a better
environment for stronger updrafts. Based on the current instability
axis and deep-layer shear profiles it appears that at least pesky
pulse-type thunderstorms won`t be out of the question. Overall, if
you have outdoor activities planned towards the end of the work week
and the Memorial Day Weekend you`ll definitely want to keep an eye
on the weather. Even if we don`t see stronger storms, remember
lightning is always a hazard with thunderstorms.

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 750 PM EDT SUN MAY 20 2018

With high pressure and a very dry air mass dominating, VFR
conditions will prevail at KIWD/KCMX/KSAW through this forecast

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 346 PM EDT SUN MAY 20 2018

Sfc high pres ridge over the Upper Lakes has led to winds under 15kt
today across most of Lake Superior this afternoon. However, with the
ridge axis setting up across southern Lake Superior, sw winds over
the n central part of the lake could gust as high as 20kt late this
afternoon. High pres will then remain over the Great Lakes region
into Tue, resulting in winds mostly under 15kt. Although a cold
front will drop s across Lake Superior Tue night/Wed morning, it
will be weak, and winds will likely remain mostly under 15kt thru
Wed and into Thu.

Upper Michigan...
Lake Superior...
Lake Michigan...


LONG TERM...Ritzman
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