Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 182024

Area Forecast Discussion
National Weather Service Marquette MI
324 PM EST Sat Feb 18 2017

.SHORT TERM...(This evening through Sunday)
Issued at 324 PM EST SAT FEB 18 2017

Pretty incredible to have such clear skies this time of year and it
not to be bitter cold. Sure is not close to cold anywhere across
Upper Michigan today. A bit chilly on the breezy Keweenaw with gusts
over 30 mph at times and temps *only* into the middle 40s. Elsewhere
temps have risen well into the 50s and even over 60 degrees in
multiple locations over cntrl cwa. Readings in Marquette city near
60 degrees have already surpassed the record for the date of 52F set
in 1954. That is a notable record as period of record for Marquette
city goes back to 1871. Record at NWS Marquette has also been broken
and additional records have at least been unofficially set at Iron
Mtn, Escanaba, Menominee, Munising, Manistique and Newberry. Lake
breezes have tried to sneak into Marquette and Munising but overall
the stiff W winds have kept them just offshore.

Skies are mostly sunny with no low clouds at all. Models that showed
that a few days ago were quite overdone. The lowest clouds are to
the north and east of Lk Superior. For the last two days the GEM
model low-level RH fields have perfomed the best and followed those
into Sun. Decent amount of high clouds are spilling across the
northern Plains toward western Great Lakes as ridge aloft flattened
last 24 hours. Expect mid clouds to increase by late tonight into
Sun with skies possibly becoming mostly cloudy on Sun. Dwpnts are
higher today than Fri so could see some fog as temps fall to the upr
20s to low 30s.

As ridge aloft builds just west of Upper Lakes on Sun and sfc ridge
slowly moves toward western Great Lakes, low-level winds may turn
just enough northwest to bring portion of lower clouds over northern
Ontario across Lk Superior and maybe into the eastern cwa, mainly
near Lk Superior. Overall with mid-high clouds streaming across and
the potential for low clouds, there should be much more cloud cover
over the area on Sun compared to Fri and today. High temps will show
quite a range with onshore winds/lake breezes near Great Lakes over
Keweenaw and east half keeping readings in the mid 30s to low 40s.
Thus, locations like Big Bay, Marquette, Munising, Escanaba will go
from near 60 degrees today to maybe not cracking 40 degrees on Sun.
Meanwhile, based on mixing to 925mb over interior west with no
influence off the Great Lakes, went with max temps into the lower to
perhaps mid 50s there.

.LONG TERM...(Sunday night through Saturday)
Issued at 324 PM EST SAT FEB 18 2017

With a mean wrn trof/ern rdg upr pattern dominating until late in
the week, a flow of Pacific air wl result in continued above normal
temps for Upr MI. There wl be several disturbances lifting out of
the wrn trof and impacting the Upr Lks as well during this time, so
overall pcpn should run above normal. The first of these pcpn events
later on Mon into Tue wl drop all rain. While limited mstr inflow wl
restrict pcpn associated with the passage of the next disturbance on
Wed, the stronger disturbance/deeper lo pres that are likely to
track thru Lower MI on Fri/Fri ngt could bring some advy to lo end
wrng snows to the cwa then. Colder air and some les wl return for
next weekend behind this disturbance.

Sun ngt...Upr MI wl still be dominated by a hi amplitude upr rdg
ahead of a disturbance/sfc lo pres lifting newd out of the wrn trof
and into the nrn Plains. Sfc hi pres rdg axis wl be shifting to the
e during the ngt, with waa clds under an incrsg sly flow btwn the
departing rdg axis and falling mslp in the Plains. Expect the lowest
min temps falling into the 20s over the e half closer to the
departing sfc hi pres. There could be some fog in this area.
Stronger s winds/more hi clds over the w wl restrict the diurnal
temp drop/potential for fog.

Mon into Tue...Shrtwv/sfc lo pres wl lift fm the nrn Plains to far
nrn Manitoba/nw Ontario near Hudson Bay. Expect thickening clds on
Mon under the incrsg deep sly flow/waa ahead of this system, with
some showers arriving over the w in the aftn. Since the lo pres wl
be moving to the w of Upr MI, pcpn that falls under the associated
slowly passing warm conveyor belt mstr ribbon wl fall as rain as h85
temps are fcst to rise up to 8-9C under the warm surge. Pwats rising
aoa an inch could result in at least some brief heavy ra. Not out of
the question there could be a rumble or two of thunder late Mon/Mon
evng over the wrn cwa, where the 12Z NAM shows h85-5 lapse rates up
to 6-6.5C/km. Depending on how quickly the attendant cold fnt
passes, winds diminish and mid lvl drying arrives over the melting
sn pack, there could also be at least some locally dense fog later
Mon ngt into Tue mrng over mainly the w half after the warm conveyor
belt shifts to the e and the steadier ra diminishes in that area.
The return of more sunshine in the presence of trailing Pacific
airmass/h85 temps as hi as 5C should allow max temps to rise aoa 50
on Tue aftn away fm lk moderation, especially over the central cwa
where the wly flow ahead of incoming hi pres rdg wl downslope.

Another concern is the potential for some hydro problems, as the
combination of recent and continuing well above normal temps/
potential for at least some brief heavy ra late on Mon into early
Tue with hier sfc dewpts at least aprchg 40 wl accenuate recent sn
melt. Fortunately, area streams are currently well blo bankfull, and
there is probably little if any ice that would cause ice jams. Model
consensus shows no more than 0.33 to 0.66 inch of rain during this
event, totals that should not cause sgnft river rises. Although the
water equivalent of the sn pack here at the NWS Office is only about
4.5 inches, at Ironwood less than 4 inches, at Stambaugh and the
rest of the scentral less than 3 inches, values not overly hi, the
sn pack over the Keweenaw and the ern sn belts no doubt has more
water equivalent. At this point, the potential for hydro problems
appears to be relatively lo.

Tue ngt-Wed ngt...Another shrtwv emerging fm the mean wrn trof is
fcst to ride ewd thru the nrn Plains and acrs the Upr Lks during
this time. Recent medium range guidance shows some sgnft differences
on the handling/timing of this disturbance, with the 12Z Cdnd model
indicating a slower and farther s track that would result in more
pcpn over Upr MI. The 12Z ECMWF has trended in that direction as
well. If the disturbance tracks farther n as shown by the 12Z
GFS/00Z ECMWF, the limited mstr inflow into this disturance would
restrict any light showers to the nrn cwa and result in a very warm
day on Wed, especially over the scentral where the wly flow would
downslope on the srn flank of the lo pres track passage. Considering
the sgnft differences and poor run-to-run continuity, wl rely on
model consensus fcst for now. The farther s 12Z ECMWF and Cndn
models indicate enuf cold air wl follow the departing lo on Wed ngt
into Thu mrng to support some chc pops for les, especially over the
Keweenaw, where these models shows h85 temps dipping to near -10C by
12Z Thu.

Late week...Focus for Thu into Sat be on the timing/track of next
shrtwv/sfc lo pres that are fcst to lift out of the wrn trof on Thu
and toward the wrn Great Lks on Fri. Longer range guidance has shown
poor run-to-run continuity on the track of these features, so
confidence of the impact on Upr MI is lo. The faster 12Z GFS shows
waa pcpn ahead of this disturbance arriving as early as Thu aftn,
but the Cndn/ECMWF models are slower and hold off pcpn until late
Thu ngt/Fri respectively. While the 12Z models yday trended farther
to the nw on the track, most of the recent model runs, especially
the 06Z GFS, showed a track farther to the se. In fact, the 06Z run
of the GFS fcst a track so far to the se thru the Lower Lks that
almost all the accompanying pcpn would miss the cwa. The 12Z runs in
general show a track thru nrn Lower MI that would result in mainly
sn as ptype except for the se. The 12Z ECWMF shows a track a bit
more to the nw, but still would result in mainly sn.  Given the mean
wrn trof and ern rdg as well as the negative tilt shown by the
models of the shrtwv lifting to the ne, suspect this bit farther nw
ECMWF track is on the right track. The arrival of colder air in the
llvl nw flow left in the wake of the disturance/sfc lo pres that
drops h85 temps toward -17 to -18C wl bring a return of les chances
on Sat.

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1248 PM EST SAT FEB 18 2017

West winds gust to 30 kts at CMX rest of the aftn. Could be light
fog at IWD later tonight but may be enough wind just off sfc to keep
fog from becoming too widespread or dense. Winds shifting to NNW on
Sun may result in scattered stratus/stratocu at CMX and SAW though
if there are any cigs they should remain lower VFR. Otherwise on Sun
at the TAF sites, plan on lighter winds with broken mid to high

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 324 PM EST SAT FEB 18 2017

No heavy freezing spray is expected into most of next week. SE winds
to 30 kts with a few gale gusts are expected late Mon into Mon night
over eastern sections. Otherwise winds should stay 25 kts or less
through the period.

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


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