Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 190828

Area Forecast Discussion
National Weather Service Marquette MI
428 AM EDT Fri May 19 2017

.SHORT TERM...(Today and tonight)
Issued at 428 AM EDT FRI MAY 19 2017

Only a couple items worth noting in the short term. Frost/freeze
occuring at this time across much of the area and some additional
frost potential tonight. Very dry air will mix down today, resulting
in minRH values of 20-30% away from the immediate Great Lakes
shorelines. NE winds will gust up to 20mph today, but recent rain
does help minimize wildfire concerns.

.LONG TERM...(Saturday through Thursday)
Issued at 344 AM EDT FRI MAY 19 2017

After a shortwave and associated sfc low lift north out of the
southern/central Plains bringing more rain and showers into the
Upper Great Lakes this weekend, most of next week is shaping up to
be a cool pattern for the Upper Great Lakes heading thru next week.
A ridge/strong positive height anomaly developing along the w coast
of N America (500mb heights reach 250m above normal near the BC
coast) beginning this weekend will support a deepening mid-upper
trough downstream into the Great Lakes region next week with
mainly periodic light pcpn events.

Over the a negative tilt mid-upper level trough lifts
ne toward the western Great Lakes, the associated sfc low is progged
to track nne, probably passing over far western Upper Mi and western
Lake Superior during the day Sun while driving an occluded front
across the fcst area. A strong surge of isentropic ascent/moisture
transport will likely spread a band of showers n across the fcst
area Sat aftn/evening. Not out of the question that there could be a
few rumbles of thunder south central and se cwa closer to better
instability gradient of warm sector as noted on MLCAPE fields. Shra
will then diminish Sat night/Sun under some dry slotting in the wake
of occluded fropa. Model averaged rainfall totals for Sat aftn/Sat
night indicate between 0.50 to 0.85 of an inch of rain across the
area. Cyclonic westerly flow on southern edge of system as it lifts
n of the area could sustain some isold/sct -shra on Sun, especially
w where deeper moisture will be wrapping back into the area.

Temps Sat will be held down by thick clouds/developing shra with
highs mostly in the 50s...except upper 40s over the Keweenaw. Sun
should be a little warmer, but again expected clouds and some
showers will keep temps generally in the 50s.

On Mon, with broad mid-level low centered just n of Lake Superior,
some isolated -shra could linger over the area under a cyclonic

Tue-Thu, Models indicate a stronger shortwave dropping into the
developing mean Great Lakes/central CONUS mid-level trough by mid
next week. Depending on the track of this wave and how wrapped up
the developing sfc low becomes, there could be some rain spreading
into the se half of fcst area Tue/Tue night with even some potential
for lingering shra into Wed. ECMWF suggests a drier solution than
either the GFS or CMC. Nonetheless, will be quite cool both days
under northerly winds on back side of low and 850mb temps dropping
to around 0C. Highs near the Lake Superior shore will probably not
make it out of the 40s either day. GFS shows the potential of yet
another shortwave dropping thru the mid-upper trough on Thu,
continuing at least some risk of isold/sct -shra.

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 125 AM EDT FRI MAY 19 2017

VFR conditions expected through the period at all sites.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 428 AM EDT FRI MAY 19 2017

Winds will be under 25kts until Sat afternoon through Sat night when
E to NE winds will gust up to 30kts. Winds will then be below 25kts
through the remainder of the forecast.

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


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