Area Forecast Discussion
Issued by NWS Marquette, MI

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274
FXUS63 KMQT 220941
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
441 AM EST Thu Feb 22 2018

.SHORT TERM...(This evening through Thursday)
Issued at 239 PM EST WED FEB 21 2018

Overall, quiet weather has begun to settled in for the
next 24 hours across Upper Michigan. Lingering light lake effect
snow showers across the west to northwest wind snow belts has
gradually diminished this afternoon as surface ridging began to lift
northeast. Ample sunshine was observed across much of western and
central Upper Michigan, where temperatures quickly rebounded into
the upper teens and 20s through the afternoon hours.

The main forecast concern over the next 24 hours are temperatures.
Tonight, surface ridging will continue to track northeast across
Upper Michigan. The resulting drier air mass, clear skies, and light
winds will give way to ample radiational cooling across the area.
Not terribly impressed with how guidance seems to be handling the
potential for colder temperatures tonight, so did make manual
adjustments to lower temperatures down below zero across the interior
west and central. Elsewhere, temperatures should easily drop into
the single digits. Thankfully, winds will be light tonight so there
will be no wind chill concerns. Thursday, warm air advection will
begin to gradually lift northward with thickening cloud cover during
the afternoon. Temperatures will warm a few more degrees compared to
today as a result, with highs climbing into the upper 20s to lower
30s. Snow chances will hold off until Thursday night, when the next
system is progged to track across the region - see the latest long
term discussion for further details.

.LONG TERM...(Friday through Wednesday)
Issued at 440 AM EST THU FEB 22 2018

Active pattern continues into this weekend. Two primary winter
weather systems affect the area first part of Fri and again Sat
night into Sun.

Bulk of snow with Fri system will be exiting northern Upper Michigan
by mid morning Fri. Mid-level shortwave and increasing moisture
advection ahead of sfc-H85 trough are main drivers for the snow.
Snow could taper off as freezing drizzle or drizzle before ending
midday Fri. Though mainly marginal snow amounts of 2-4 inches
(heavier on the Keweenaw Peninsula) are expected mainly from late
this evening through mid morning Fri, the impact could be higher due
to the timing of heaviest snow occurring just before or during the
Fri morning commute and as the snow will be wet/heavy with SLRs less
than 15:1.

Small chances for lake effect linger into Fri night as H85 temps
fall toward -10c and there is widespread low-level moisture. High
pressure builds across on Sat and with mostly sunny skies, should
see high temperatures well into the 30s. Next system will quickly
approach from the southern Plains on Sat evening. Shortwave that is
main instigator for this system currently is sliding along the
Pacific northwest coast as seen in the WV loop. As this shortwave
emerges onto the central Plains Sat, expect lee cyclogenesis to
result in 995-1000mb sfc low over IA or northern MO by Sat evening.
Shortwave becomes negatively tilted as it lifts toward Upper Great
Lakes late Sat night into Sun morning. Associated sfc low deepens to
below 990mb by Sun morning with a location somewhere over central or
eastern Upper Michigan. Given the strengthening system and mixing
ratios of 3-3.5g/kg, can see why some of the models are generating
12 hour qpf either from 00z-12z Sun or 06z-18z Sun over 1 inch to
the west of sfc low lifting through the region. GFS and tail end of
NAM indicate heaviest qpf stays over far west or more to the west of
our forecast area. GEFS probabilities of qpf over 0.50 or 1.00 inch
also tilts more to far western forecast area and on to the west.
We`ll see if these trends continue to hold up. If so, there could be
a period of very heavy snow over western U.P. Sat night into Sun
morning with moderate snow changing to a wintry mix of snow/sleet
and freezing rain/freezing drizzle over central and eastern forecast
area. After some data issues last couple days, do have the EC back
and that also indicates best chance for heavier qpf over far western
tier. With strong sfc low, chances are winds will turn breezy Sun
aftn into Sun evening. Since snow preceeding winds will be wetter
and temps by Sun aftn will be back into the 30s, blowing snow should
be limited. Given the strong system and moisture inflow present,
this system will continue to be monitored, but before really
tackling it will first have to get through tonight into Fri system.

Light LES possible in wake of the Sun system Sun night into Mon.
Marginal temps and decreasing low-level moisture as main system
quickly lifts into northern Quebec should limit extent of LES.
&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1250 AM EST THU FEB 22 2018

VFR ceilings and visibilities are will prevail through about 00Z
Thursday with light winds.  As a clipper system approaches from the
southwest, MVFR conditions are expected at KIWD and KCMX by about
05Z in accordance with lowered ceilings and visibilities.  There is
somewhat low confidence that MVFR conditions will be met before 05Z
Thursday depending on the speed of the incoming system, but exact
timing will be refined in later updates.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 239 PM EST WED FEB 21 2018

20 to 30 knot winds over Lake Superior will relax to less than 20
knots by Thursday morning as high pressure lifts across the region.
Expect winds to remain below 20 knots through much of Saturday. A
strengthening low pressure system is progged to track across the
Upper Great Lakes later this weekend; therefore, expect winds to
ramp up to between 20 to 30 knots.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory from 10 PM EST /9 PM CST/ this evening
     to 10 AM EST /9 AM CST/ Friday for MIZ002-004-005-009>013-
     084.

  Winter Storm Warning from 10 PM this evening to 10 AM EST Friday
     for MIZ001-003.

Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...Ritzman
LONG TERM...JLA
AVIATION...Borchardt
MARINE...Ritzman



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