Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 200858

Area Forecast Discussion
National Weather Service Marquette MI
458 AM EDT Tue Mar 20 2018

.SHORT TERM...(Today and tonight)
Issued at 457 AM EDT TUE MAR 20 2018

WV imagery and RAP analysis indicated confluent mid/upper level flow
through nrn Ontario into the nrn Great Lakes between a trough over
Quebec and a ridge through northwest Ontario. This supported a sfc
ridge from nrn Ontario into the northern Great Lakes which was
bringing cool dry air into Upper Michigan on ene low level winds.
An area of lake effect clouds and a few flurries has spread into
north centrl Upper Michigan. Otherwise, IR loop showed an area of
mid clouds spreading from MN and nw WI into portions of western
Upper Michigan.

Today, continued ene with min temps to -12C at the top of the
shallow cold layer to 2k-3k ft will provide only marginal
instability for any LES. So, mainly just a few flurries at most are
expected early. The very dry low level air with dewpoints around 10F
will also be unfavorable for any diurnal -shsn development. In
addition, increasing mid clouds will also limit sfc heating. High
temps, similar or slightly lower than Monday, will only climb into
the mid 20s north to around 30 south.

Tonight, mid/high clouds remaning over the region will limit
radiational cooling. However, temps in the cold airmass will still
drop into the single digits inland with teens near the Great Lakes.
Additional dryning and lowering inversion heights with winds
veering easterly will be unfavorable for any additional light LES
or flurries.

.LONG TERM...(Wednesday through Monday)
Issued at 439 AM EDT TUE MAR 20 2018

Quiet weather is expected to persist through much of the week. A
weak sheared-out shortwave trough will bring an increase in mid-
level clouds tonight into Wed but low-level dry air in a ne flow
circulating around a Hudson Bay high will ensure dry conditions. The
mid level clouds combined with the cool ne flow off Lake Superior
will keep temps blo normal Wed with highs in the upper 20s north to
lower to mid 30s south. Clearing skies from the west behind
departing shortwave along with light winds should make for chilly
conditions Wed night. Forecasted on the lower end of model
guidance as min temps could approach zero at a few of the typical
cold spots over the western interior.

Building 5h heights ahead of an advancing upper ridge from the
west will yield more sunshine Thu and Fri as temps push back
toward normal with highs in the lower to mid 30s north to lower
40s south.

Heading into the weekend, models now in good agreement showing
amplified ridge from Hudson Bay into the Western Great Lakes
suppressing next system well south moving through the Central Plains
and Ohio Valley on Saturday. Expect dry conditions through the
weekend although there will be an increase in clouds from the
Central Plains system Fri night into Saturday. E-SE flow circulating
around the Hudson Bay high and presence of some clouds will keep
temps slightly blo normal over the weekend with highs generally in
the 30s.

GFS shows a shortwave lifting ne through the Upper MS Valley into
Ontario bringing the next chance of light precipitation Sun night
into Mon. GFS solution is certainly most aggressive with this
shortwave breaking down the strong ridge in place while the ECMWF
and CMC hold on to ridging and drier air through Monday. Given
strength of ridge, persistence and drier solution seems to be the
way go.

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 122 AM EDT TUE MAR 20 2018

VFR conditions and light winds are expected through the TAF period.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 457 AM EDT TUE MAR 20 2018

High pressure building in from Ontario will produce ne winds around
25 knots over western Lake Superior today and over the east tonight.
Otherwise no significant winds are expected through the forecast
period, with winds generally staying at or below 20 knots.

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


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