Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/05/20

Area Forecast Discussion

National Weather Service Marquette MI

 544 PM EST Wed Nov 4 2020

.SHORT TERM...(This evening through Thursday)
Issued at 358 PM EST WED NOV 4 2020

WV imagery and RAP analysis indicated a mainly zonal pattern across
southern Canada and the northern CONUS. Shortwave troughs were
located over far nw Ontario and over southern Saskatchewan. At the
surface, low pressure over northwest Ontario was dragging a weak
trough into northwest MN while a cold front lagged over southern
Manitoba. Brisk southwest flow prevailed across Upper Michigan
between the low and high pressure over the Ohio Valley.

Tonight, expect the trough to move through and cold front to move
through Upper Michigan tonight with winds veering westerly. Little
more than a band of mid clouds or cirrus will move through late
given the very dry conditions through the region. Enough boundary
layer mixing should prevail to keep temps dropping below the upper
30s inland while downslope flow maintains temps int the mid 40s
north central near Lake Superior.

Thursday, even with 900 mb temps dropping to around 7C behind the
front (around inland mixed layer heights) temps will remain well
above seasonal averages. Again boosted forecast max readings
closer to the model 90 percentile. Temps should range from the low
to mid 60s south to the mid 50s north, with some onshore cooling
from Lake Superior.

.LONG TERM...(Thursday night through Wednesday)
Issued at 430 PM EST WED NOV 4 2020

Dry and warm conditions will continue until the beginning of next
week, as the temperature inversion and low level dry layer look to
stay in place. Come Monday, a cold front will move through the area
slowly, eroding the dry layer and bringing rainfall to Upper
Michigan. As this cold front tracks through our area, look for
temperatures to cool enough to see some snow possible on the
backside of the cold front in the west. Also, there appears to be a
low pressure moving through our area Wednesday, which looks to bring
more mixed precipitation back into our area late in the forecast
period. Further details are below.

The jet stream will be too far north for us to be affected by a
shortwave that will move through northern Ontario Thursday night and
Friday. The jet stream will, however, dip over the western US during
that time period, allowing for cyclogenesis to occur and thus the
creation of a synoptic low. This synoptic low looks to develop a
warm front over northern Ontario Friday night/Saturday. This front
looks to bring cloud cover and waa over the U.P.. As the warm front
moves north and the cold front approaches from the west Sunday,
expect stronger southerly winds. The NAEFS and ENS have winds in the
90th percentile from Sunday night into Monday night. Therefore,
winds could very easily be stronger than what the NBM was placing in
the grids for Sunday and Monday. However, there was not enough
confidence to include these higher numbers in the grids; just
something to keep an eye over the course of the next few days. As
the cold front moves through Sunday night into Monday night/Tuesday,
heavy rainfall may be possible, as PWaTs look to be in the 97.5th
percentile according to the NAEFS and ENS. On top of this, mid and
upper level winds look to be in the 90th percentile as the cold
front moves through, hinting at highly favorable conditions for
parcel uplift. At the back end of the cold front, snow will look to
mix in, particularly over the west, as temperatures will have
cooled.

As the cold front finishes moving through the area Tuesday, look for
another low pressure to develop in the southern Rockies and quickly
lift northeast. It looks to move through our area Tuesday
night/Wednesday morning, and with it bring rain and snow over the
Upper Peninsula, with more snow west and more rain east. Expect
precipitation chances to diminish over the daytime hours Wednesday.

A final note worth mentioning is that temperatures for the early
part of the extended period look to be exceedingly warm. NAEFS and
ENS have max temperatures in the 90th percentile at the 850 mb
level. That, and the waa associated with the warm front/ahead of the
cold front may bump up temperatures further than what is currently
in the grids. Also max temperatures may be higher Monday; however,
given that there was a difference in model guidance for Monday
temperatures, decided not to change increase the temperatures from
the NBM. It is all dependent on how strong the waa is ahead of the
cold front.
&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 544 PM EST WED NOV 4 2020

Expect VFR conditions through the forecat period.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 358 PM EST WED NOV 4 2020

SW winds could reach 20 kts ahead of a cold front, then veer west
and then NW Thursday morning behind the front before diminishing
to less than 20 kts on Thursday. Winds should then remain at or
below 20 knots through Sunday.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLB
LONG TERM...TAP
AVIATION...07
MARINE...JLB