Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/02/20
Area Forecast Discussion
National Weather Service Marquette MI
615 PM EST Sun Nov 1 2020
.SHORT TERM...(This evening through Monday)
Issued at 431 PM EST SUN NOV 1 2020
Water vapor imagery and RAP analysis show a vigorous shortwave trof
moving across the Great Lakes region, but now e of the fcst area. As
expected, it was a big wind producer on the backside due to tight
pres gradient/caa and vigorous enhancement from the isallobaric
wind. Peak wind gust on Lake Superior was 74mph at Stannard Rock
and on the land 2 locations reached 70 or higher, Copper Harbor
(KP59) at 70mph and a public report of 71mph at the Big Bay
lighthouse. Lake enhanced snow has been rapidly diminishing/ending
from w to e over the last several hrs in conjunction with the
sharp loss of deeper moisture and drying in the low-levels as
well. In fact, skies have been clearing from western Lake Superior
into western Upper MI. Under the strong winds, the heavier snow
from this lake enhanced snow event was displaced farther inland
than normally occurs. The Keweenaw missed out on any meaningful
snow as upslope enhancement was displaced se of the peninsula.
Heavier snow band tied to Lake Nipigon preconditioning waivered
around in central Alger County for a while during the later
morning/early aftn, but that band has since faded away due the
sharp upstream drying. Transient nature of the band limited
accumulations, but suspect there may have been a few inches of
snow from the band well inland from Lake Superior down into ne
Delta County and western Schoolcraft County.
Will allow ongoing headlines for the land to expire as scheduled.
Given the rapid diminishing of the lake effect snow, would be able
to cancel the last advy segment early, but will let it ride for now
given winds still gusting into the wind advy range. Last of the
-shsn/flurries over the e will be done by mid evening at the latest.
Clearing will continue progressing eastward from western Upper MI
this evening. Thus, much of central and western Upper MI will have
at least a period of clear skies this evening. This clearing will be
short-lived as a shortwave now approaching northern Manitoba streaks
se across northern Ontario late tonight/Mon. Strong waa regime
developing in response to this wave will result in high and mid
clouds developing/spreading across the area during the night. Given
the dry antecedant low-levels, don`t expect any pcpn across the fcst
area with this wave. Pcpn associated with the waa/isentropic ascent
should occur farther ne and e, closer to the shortwave track and
deeper into the retreating cold air where moistening of the low-
levels would be more likely to occur. Never really get into a good
period of light low-level wind fields tonight due to the
aformentioned shortwave dropping into northern Ontario, so temps
won`t fall off significantly during the window of clear skies. Some
of the traditional interior w half cold spots may slip blo 20F.
Otherwise, 20s will be the rule.
Will be on the breezy side on Mon, especially during the morning as
the low-level wind max associated with the shortwave translates
across the area. Otherwise, under a mix of clouds/sun, temps will
rise into the 40s across the board.
.LONG TERM...(Monday night through Sunday)
Issued at 319 PM EST SUN NOV 1 2020
Not much in the longterm period weather wise, which has been the
theme the last 3 model cycles or so. With a positive NAO/AO favored
through the next 10 days and the PNA favored to remain negative to
neutral, this sets the stage for favored above normal temperatures
across the central and eastern US. Model ensembles suggest ridging
over the central CONUS on Tuesday with a slight trof on Thursday
before the ridging shifts to the eastern CONUS with troffing
developing along the West Coast.
The only real change to the forecast through this week was to adjust
all max temperatures to 75th percentile of guidance. As is usually
the case, NBM remains slow to catch on to this regime change with
deterministic models suggest this warm up for a while.
Deterministic models show 850mb temps climb to around 12 to 14C on
Tuesday evening, which persists right into Wednesday. This puts
Tuesday`s highs in the mid to upper 50s and upper 50s to low 60s on
Wednesday. Weak troffing brings a "cooldown" on Thursday with 850mb
temps falling back to around 10C.
As the aforementioned trof takes hold across the West Coast, ridging
shifts to the eastern CONUS with SW flow across the Midwest. Friday
looks to warmup back closer to the 60s, while Saturday looks like
the warmest day of the stretch with 850mb temps climbing to an avg
15C between GFS/GEM/EC. Fcst is likely not as warm as we will end up
on Saturday with low to mid 60s across the west and upper 50s to 60
in the east.
This warmer weather continues into Sunday before models suggest
another wave and associated cold front on the UPs doorstep sometime
Sunday into Monday, with the GFS a day or so ahead of the GEM/EC. If
we want to start looking at the next time PoPs enter the fcst, we
have to start getting into make believe land at model hour 192 with
a cold front on the GEM/EC and model hour 180 with the same cold
front on the GFS. Beyond that, the GFS and GEM suggest a deepening
low to move through the Great Lakes on Wednesday next week, and with
850mb temps progged at -10 to -12C...could be the return of snow
across the Upper Peninsula.
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 614 PM EST SUN NOV 1 2020
VFR conditions will continue through the period at all sites.
Increasing winds above nocturnal inversion late tonight into early
Mon morning will lead to a short period of LLWS at IWD and SAW.
Will continue to be gusty at CMX through the forecast period.
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 431 PM EST SUN NOV 1 2020
On going gale/storm event is winding down. Lingering gales/some
storm gusts over the e half of Lake Superior will diminish over the
next several hrs with winds blo gale force by mid evening. A low
pres dropping se across far northern Ontario will bring another
increase in winds late tonight/Mon. Westerly gale force wind gusts
to around 35kt should redevelop over w and central Lake Superior
late tonight into Mon morning. A few gale gusts may reach to eastern
Lake Superior during the day on Mon into Mon evening. Winds will
then diminish from w to e across Lake Superior Mon aftn and Mon
night. Winds across the lake should be under 15kt by sunrise Tue.
Winds should then stay mostly blo 25kt thru the mid to late next
week period as only weak low pres systems track e, passing by to
north of Lake Superior.
Winter Weather Advisory until 7 PM EST this evening for MIZ006-
Lakeshore Flood Warning until 9 PM EST this evening for
Storm Warning until 10 PM EST this evening for LSZ251-267.
Storm Warning until 7 PM EST this evening for LSZ249-250-266.
Gale Warning from 5 AM to noon EST Monday for LSZ245>248-265-266.
Gale Warning until 7 PM EST this evening for LSZ243>248-264-265.
Gale Warning from 3 AM EST /2 AM CST/ to 10 AM EST /9 AM CST/
Monday for LSZ241>244-263-264.
Gale Warning from 2 AM EST /1 AM CST/ to 8 AM EST /7 AM CST/
Monday for LSZ162.
Storm Warning until 7 PM EST this evening for LMZ221-248-250.