429 
FXUS63 KMPX 101749
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1149 AM CST Wed Mar 10 2021

.UPDATE...
Issued at 717 AM CST Wed Mar 10 2021

Updated the forecast to include severe wording late this afternoon
and early evening in conjunction with the SPC upgrade to slight risk.
A few updraft helicity tracks within CAMs have been impressive for
several runs, so confidence is increasing a bit for some supercell
thunderstorms later today across southern/eastern MN and western WI.
Temperatures across southern Iowa are already in the 60s with mid 50s
dew points north into central and northern Iowa. It seems likely as
southerly flow increases ahead of the low that we have a better
chance to tap into better instability, which was the main uncertainty
for severe weather this afternoon. 

&&

.SHORT TERM...(Today through Thursday)
Issued at 424 AM CST Wed Mar 10 2021

Multiple hazards, ranging from accumulating snow to tornadoes, are 
possible today and tonight as a classic spring system bisects the 
forecast area. This section will discuss each side of the system 
separately, as drastically different types of weather are expected. 

On the large scale, a cold front is sagging southeast into northern
Iowa, southeastern Minnesota, and northern/central Wisconsin early 
this morning. A large positively tilted trough extending southwest 
to much of the West Coast will send a short wave northeast across the
Plains and Upper Midwest today. Surface low pressure will propagate
northeast from eastern Nebraska to east central Minnesota today, then
to northern Wisconsin this evening. The front that cleared to the
southeast will begin to lift back north as a warm front this morning
as the low approaches from the southwest. One of the biggest 
uncertainties today is how far north the boundary will reach. An 
increasing number of solutions suggest it will reach at least the 
southern and eastern metro area by late this afternoon. Highs south 
of the front should reach the 60s, whereas north of the front they 
will struggle to reach the low to mid 40s, with even some 30s across 
western Minnesota.

1. Southern/Eastern Minnesota into Wisconsin:

Showers and thunderstorms are developing across western Iowa early
this morning and are beginning to lift into southern Minnesota. This
activity will become more widespread as the early morning progresses,
then organize into a band and lift north into central Minnesota 
during the afternoon. Scattered activity should continue this 
afternoon behind the steadier rain. The system's dry slot will reach 
south central Minnesota mid to late afternoon. Some breaks in the 
cloud cover are possible which would send temperatures into the 60s 
in the warm sector. Lapse rates are not impressive, however rich low 
level moisture may still manage to generate sufficient CAPE (AOA 500 
J/kg), especially if surface temps do reach the 60s. As the low
reaches east central Minnesota late this afternoon, a cold front will
trek east across southern Minnesota. Thunderstorm redevelopment along
the front is conditional on whether instability can build. If it
does, a very strongly sheared environment with impressive hodographs
and backed surface flow will allow low-topped supercells to develop 
with all severe hazards possible, including tornadoes. The best
chance for this will be east of a line from St. James to the Twin
Cities and Rice Lake, but ultimately it will depend how far north 
the triple point reaches. The cold front will continue eastward 
early this evening, clearing the Eau Claire area by 9 PM and taking 
the thunderstorm chances with it.

Following the front, low level cold air advection will rapidly erode
any warm, moist inversion and increase mixing depth. 6 hour pressure
rises of 12 mb and continued very strong wind aloft will bring the
potential for damaging wind gusts to southern Minnesota into western
Wisconsin this evening and early overnight. Forecast soundings
suggest 50 kt winds at the top of the shallow boundary layer, and
wouldn't be surprised to see at least some 40-45 kt gusts reach the 
surface at times. Posted a Wind Advisory southeast of a line from St.
James, to the southeastern Twin Cities metro, to Rice Lake.

2. Central and western Minnesota:

On the cold side of the system, a band of snow will reach far 
western Minnesota by late morning, but surface temperatures should be
warm enough to negate much impact through at least mid afternoon.
Temperatures will cool to near freezing late this afternoon and snow
will begin to accumulate through the evening. The snow will taper off
from southwest to northeast following the low. Accumulations will
range from 3 to 6 inches west of Canby to Glenwood and Little Falls,
but the higher end may be more likely if the snow is more intense 
this afternoon and/or surface temps cool to freezing earlier. Some
patchy blowing snow is possible as winds gust to 35 mph this 
evening. Posted a Winter Weather Advisory for this area mid afternoon
through evening.

.LONG TERM...(Thursday night through Tuesday)
Issued at 424 AM CST Wed Mar 10 2021

A cool Thursday night is forecast (compared to the weather we just 
had) with lows in the upper teens across central MN to upper 20s in 
southern MN. A shortwave within the northern stream will slide 
southeast from Manitoba into the Upper Great Lakes during Thursday 
night. While moisture will be marginal, the vertical profile could 
saturate enough over central MN to northwest WI to create flurries. 
Thus, have added slight chance PoPs to our extreme northern and 
northeastern counties Thursday night. Friday and Saturday look dry 
as upper-level convergence from converging split flow and a left 
entrance region of an upper-level jetstreak place themselves over 
MN/WI. Friday's highs are forecast to be in the mid-30s to lower 40s 
with Friday night's lows being similar to Thursday night's. Saturday 
will be slightly warmer (near 50) as the cool air mass that followed 
the aforementioned trough makes its exit east.

Our next chance of precipitation is currently progged for Sunday 
into Monday. A bowling ball of an upper-level closed low is forecast 
to wobble eastward out of the southwest CONUS into the Central 
Plains. The GEFS, EPS, GFS, and ECMWF all hint a slight northward 
meander in the low's track, which would place the southern halves of 
MN and WI within the system's periphery. While the system would be 
vertically stacked and weakening as it travels though the central 
CONUS, a widespread band of precipitation should be present near and 
along its associated warm front. We will continue to monitor this 
system as the forecast, weak split flow regime does not offer great 
confidence for a potential storm track. What is looking more likely 
is that temperatures will remain near normal (highs in the 40s and 
lows in the 20s) throughout the first half of next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1145 AM CST Wed Mar 10 2021

A surface front lied across southeast Minnesota, and portions of 
west central Wisconsin, south of Red Wing to Ladysmith. North of this
front, LIFR conditions prevailed with some VFR conditions between 
the precipitation and drier air to the north. The main concern is 
TSRA potential over the next few hours as TSRA are expected to 
develop along this front and move northeastward rapidly. Although 
these storms will likely be isolated with brief periods of heavy 
rainfall, or perhaps a hailstone or two, the main aviation concern is
IFR/LIFR conditions continuing north of this frontal boundary. The 
other concern is in the far northwest MPX CWA where a period of heavy
snowfall is likely from KMOX-KAXN-KBRD later today, and into the 
evening. Currently, only KAXN is the only airport that will likely 
receive several inches of snow. Elsewhere, as the precipitation 
changes over to snow, accumulations should be less than an inch. By 
the evening, winds will begin to increase and shift to the 
west/northwest. Gusty winds will continue through the forecast period
with conditions slowly improving. 

KMSP...

Timing of TSRA is the main concern but again, the storms will likely
be brief and last 15 mins. There is a potential of hail with the
storms this afternoon along with localized gusty winds. The best time
frame for the storms will occur between 21-01z. However, this is more
consistency with the forecast than confidence. TSRA currently
overhead will likely move off to the northeast by 18z, but anytime
this afternoon, TSRA are possible. IFR/MVFR conditions will last
through most of the TAF period with slowly improving conditions
Thursday afternoon.  

/OUTLOOK FOR KMSP/

Fri...VFR. NW wind around 5 kts. 
Sat...VFR. SW-W wind 5-10 kts.
Sun...VFR. E-ENE wind 10-15 kts. 

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...Winter Weather Advisory from 3 PM this afternoon to midnight CST 
     tonight for Douglas-Lac Qui Parle-Morrison-Pope-Stevens-Swift-
     Todd.

     Wind Advisory from 7 PM this evening to 3 AM CST Thursday for 
     Dakota-Goodhue-Scott-Washington.

     Wind Advisory from 5 PM this afternoon to midnight CST tonight for 
     Blue Earth-Faribault-Freeborn-Le Sueur-Martin-Rice-Steele-
     Waseca-Watonwan.

WI...Wind Advisory from 7 PM this evening to 3 AM CST Thursday for 
     Barron-Chippewa-Dunn-Eau Claire-Pepin-Pierce-Rusk-St. Croix.

&&

$$

UPDATE...Borghoff
SHORT TERM...Borghoff
LONG TERM...CTG
AVIATION...JLT