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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KMPX 191559
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1059 AM CDT Mon Apr 19 2021

.UPDATE...For 18Z Aviation discussion below

&&

.SHORT TERM...(Today through Tuesday)
Issued at 357 AM CDT Mon Apr 19 2021

Extensive cloud cover in cyclonic flow will be the main story today,
along with much cooler temperatures. Scattered flurries are being
reported at some AWOS stations this morning. Mixing will deepen today
and LCLs will rise, brining saturation into the DGZ. Flurries may
become more numerous across eastern MN/WI this afternoon, and some
could build to snow showers. No accumulation is expected.

The loss of daytime instability should allow clouds to dissipate
relatively quickly this evening with mostly clear skies tonight. The
process will repeat Tuesday as another short wave rotates through
from the northwest. However, the depth of moisture will be increased
and steep lapse rates through this moisture layer, also coincident
with the DGZ, should allow for isolated to scattered snow showers to
redevelop by late morning. Despite temperatures in the low to mid
40s, wet bulb temperatures will remain below freezing throughout the
column due to inverted V/very dry profiles in the boundary layer.
What ever can make it to the ground without sublimating will very
likely be snowflakes. Coverage and intensity may be increased
Tuesday again due to the better moisture and instability throughout
the DGZ. Introduced 20 PoPs area wide through Tuesday afternoon.

.LONG TERM...(Tuesday night through Sunday)
Issued at 357 AM CDT Mon Apr 19 2021

A very cold airmass will remain in place during the start of the
extended period with occasional rain or snow showers depending on
surface temperatures. The deep circulation around the upper trough
diving southward over the next couple of days, will lead to steep
lapse rates which will cause these rain/snow showers.

Once the mean trough moves east of our region will temperatures
begin to moderate late this week. The mean upper level flow will
become more zonal with subtle shortwaves moving eastward along this
increasing fast flow. Models still suggest the more active storm
track will occur across the southern CONUS late this week, and into
the weekend.

There is still lots of uncertainty on the amount of precipitation
expected late this week. Timing and questionable moisture return are
the key factors on forecast trends. Over the past couple of days,
chance percentages are the rule due to these uncertainties. Once we
get a better handle on the strength of the shortwave/s and moisture
depth, will the forecast trend wetter or drier.

The week of April 26th looks more unsettled due to the transition to
the stronger zonal flow, and possibly a more active pattern as a
long wave trough begins to develop across the Rockies, and into the
Plains.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1058 AM CDT Mon Apr 19 2021

The stratocu deck will bring mostly low-end VFR ceilings through this
afternoon, with pockets of high-end MVFR ceilings and flurries/light
snow showers. The deck will scatter out this evening. Northwest winds
around 15 knots gusting to 25 knots will weaken to speeds below 10
knots this evening.

KMSP...
Visibility/ceilings could briefly lower to around 5SM/2500FT with
scattered flurries or even light snow showers this afternoon.

/OUTLOOK FOR KMSP/

Wed...VFR. Wind NW 15G25 kts.
Thu...VFR. Wind WSW 10G20 kts.
Fri...VFR. Slgt Chc MVFR/-SHRA. Wind SW 10G20 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&

$$

SHORT TERM...Borghoff
LONG TERM...JLT
AVIATION...LS