Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 192003

Area Forecast Discussion
National Weather Service Marquette MI
403 PM EDT Fri May 19 2017

.SHORT TERM...(This evening through Saturday)
Issued at 319 PM EDT FRI MAY 19 2017

High clouds have overspread much of the area today and have limited
our mixing and diurnal heating this afternoon. This has resulted in
slower warming through the afternoon and dew points running a bit
higher. High pressure continues to push east across northern
portions of Lake Superior this afternoon, and rain showers across
southern Wisconsin have continued to wane as they run into a drier
air mass and better large scale subsidence.

Tonight the big question will be how low temperatures get. Given the
high clouds expected, do not expect temperature to drop as low as
they did last night. Generally speaking, low to upper 30s are
expected. It is possible that a few locations may see temperatures
around or just below freezing, especially across the higher terrain
in the interior west and central. During the day Saturday, cloud
cover will be on the increase as mid-level clouds thicken ahead of
an approaching area of low pressure. The surface pressure gradient
will also increase, bringing gusty easterly winds across the area.
As warm air advection overspreads the region, ahead of low pressure
lifting out of the Middle Mississippi River Valley, rain showers
will lift north into Upper Michigan through the afternoon and
evening hours. Initially, given how dry the air mass is overhead, it
may take a while for the low levels to moisten up enough for
precipitation to reach the ground; therefore have delayed the
arrival of precipitation a bit. The instability looks like it will
remain south of the area and lapse rates are quite unimpressive, so
opted to leave out mentions of thunder through the afternoon and
evening hours. Given the more stable airmass in place, expect
precipitation to remain more stratiform; therefore, do not think
rainfall rates will be terribly impressive.

.LONG TERM...(Saturday night through Friday)
Issued at 403 PM EDT FRI MAY 19 2017

After a vigorous mid/upper level shortwave lifts northeast through
the nrn Great Lakes into nrn Ontario, a high amplitude pattern will
prevail through next week with a ridge over the wrn CONUS and a
downstream trough through the cntrl and east. Expect continued below
normal temps with mainly light pcpn as the stronger moisture inflow
and shrtwvs remain to the south of the area.

Saturday night into Sunday, The models were in reasonable agreement
showing the best 300k-305 isentropic lift and QPF ahead of the low
and shrtwv lifting northeast through the cwa btwn 00z-06z. Later
Satruday night into the morning, the dry slot will move in, with
diminishing rain or drizzle as lower level isentropic lift continues
with while mid level drying takes over. A lull in the pcpn into the
afternoon may give way to sct -shra late in the day into the evening
as wrap-around moisture pcpn moves in from the west and lingers
through Sunday night. Under mostly cloudy skies, highs will be
limited to the mid to upper 50s with lows falling into the low to
mid 40s.

Monday, any pcpn associated with moist cyclonic flow around the mid
level low north of Lake Superior should diminish by afternoon as the
low gradually lifts to the northeast.

Tue-Wed, there is more uncertainty with the evolution of the mid
level trough and the position of the next shrtwv digging into the
wrn Great Lakes. The bulk of the rain should remain south of Upper
Michigan as the ECMWF/GEM have trended toward the GFS/GEFS.

Thu-Fri, with a transition to nw flow toward the end of the week,
there is potential for a shortwave to slide into the region that may
bring a chance of pcpn. However confidence in any details with this
feature is low given increasing model/ensemble spread.

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 142 PM EDT FRI MAY 19 2017

VFR conditions will prevail over the next 24 hours. Towards the end
of this TAF period, rain showers will begin to lift north across the
area as low pressure lifts north towards the area. Winds will also
increase and become gusty during the day tomorrow as the pressure
gradient increases. These rain showers will likely impact all
terminals through Saturday afternoon.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 319 PM EDT FRI MAY 19 2017

Winds of 10 to 15 knots are expected for the rest of the day today
and into the overnight hours as high pressure moves over northern
portions of the lake. Tomorrow, winds will increase to 20 to 30
knots through the day and persist through the overnight hours.
Winds will begin to diminish to 15 to 20 knots by Sunday
afternoon. Through the middle of next week, winds are expected to
be around 15 to 20 knots, and then they will further decrease to
around 10 to 15 knots through the end of the next week.

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


SHORT TERM...Ritzman
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