Area Forecast Discussion Issued by NWS Twin Cities, MN
000
FXUS63 KMPX 180834
AFDMPX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
334 AM CDT Mon Mar 18 2024
.KEY MESSAGES...
- Elevated fire weather conditions persist through the middle of
the work week (peaking on Tuesday).
- Gusty northwest winds return Tuesday, with gusts up to 40 mph
possible.
- Confidence is increasing in the potential for accumulating
snow across the region Thursday.
- Active pattern sets up for the weekend and early next week.
&&
.DISCUSSION...
Issued at 332 AM CDT Mon Mar 18 2024
It`s another brisk night with northwest winds still sustained 10 to
15 mph but the gustiness has tapered off. Temperatures are currently
in the upper teens and low 20s across Minnesota and western
Wisconsin. Wind chills are in the single digits everywhere but the
core of the Twin Cities metro and serves as a pleasant reminder than
cold and wintry weather conditions are still possible in March &
April. A stratocu layer is present over the region and like last
night is producing areas of flurries & very light snow showers. This
cloud layer will scatter out after sunrise, but we`re going to have
a broken mid-level deck building in this afternoon to replace it.
Temperatures will warm into the mid to upper 30s and winds will
shift from the northwest to the west and eventually southwest
tonight.
The driving force behind the wind shift is a quick moving clipper
system that will track along the international border before
dropping into the northern Great Lakes region on Tuesday. Tuesday
still looks like the warmest day this week with highs in the mid
40s. This clipper will bring the thermal ridge & associated sfc
front through Monday night. The timing of this means we`ll likely
trend a few degrees colder with our highs on Tuesday since we`ll be
in cold air advection after sunrise Tuesday. Winds will turn back to
the northwest Tuesday morning and the gustiness will return Tuesday
afternoon. Winds will be sustained 20 to 25 mph with gusts up to 40
mph making it feel similar to this past weekend. With forecast winds
near advisory level, attention will turn back to fire weather
concerns. The strong winds, low minimum RH`s, and very dry fuels
will lead to elevated fire weather concerns Monday through
Wednesday. We`ll see fire weather concerns peak Tuesday. Our cold
advection will flip the temperatures back to the cold side of things
for Wednesday, with below normal highs back in the low 30s.
An active pattern is set to return for the second half of the week.
You knew it had to snow again eventually... right? There is always a
level of uncertainty with any system that`s still over 96 hours out
but forecast confidence is beginning to increase due to the
consistency across guidance. A mid-level shortwave will extend
eastward across the Upper Midwest Thursday into Friday. Warm air
advection will increase ahead of the system across the Northern
Plains and Upper Midwest on Thursday. This WAA will lead to a broad
area of isentropic ascent tied to a weak warm front that will lead
to the development of a northwest to southeast oriented band of
light snow across the Dakotas that`ll track into Minnesota and
Wisconsin Thursday afternoon. There is still a vague signal for the
potential of an embedded band of heavier snow driven by low level
frontogenesis that we`ll have to keep an eye out for once hi-res
guidance gets into range. Conceptually, guidance has an impressive
temperature gradient at 850mb associated with the weak low level
warm front. This feature is present at 700mb, too but is displaced
to the northeast of the 850mb gradient. Conceptually, it should lead
to a narrow band of heavier snowfall driven by an FGEN circulation.
Unfortunately, these features aren`t easy to pick up until hi-res
guidance is available, which would be Tuesday night & Wednesday, so
until then we`ll focus on the broad snow & the associated impacts
from that. Ensemble mean QPF has trended up since last night`s 00z
runs across all of the major ensemble systems (EPS/GEFS/GEPS). They
highlight a broad band of 0.20 to 0.30" QPF across MN & W WI by
Friday morning. The 00z ECMWF QPF has trended higher as did other
globals. The GFS continues to be the outlier in advertising 0.50 to
0.60" across a broad area of MN and WI, which is unreasonable given
the speed &evolution of this system, but a narrow region of higher
QPF is still in play per FGEN. Blended guidance is similar to the
00z ECMWF with a band of 0.20 to 0.30" across portions of central
Minnesota and western Wisconsin. NBM PoPs have ticked upwards into
the 70 to 80% range. This lines up with higher confidence for
precipitation on Thursday.
Here`s a summary: It appears likely that a broad area of snow will
impact the Upper Midwest on Thursday & Thursday night, with
increasing confidence for a few inches of accumulation despite
recent warmth and thawed ground. Specifics with regards to timing,
amounts, placement, intensity, and travel impacts will come into
greater detail as additional guidance becomes available. If you`re
put away your snow shovel or winter gear it`s not too late to get it
back out! You have a few days to prepare.
Beyond Thursday, our attention turns to next weekend (and early next
week). Guidance suggests a deep trough will dig into the western
CONUs with several shortwaves embedded within the broad longwave
trough. There is a significant amount of uncertainty with respect to
the evolution of this period, but there is remarkable consistency
with the signal for potential of a few waves of precipitation across
the Midwest. The first window is Saturday into Sunday as a shortwave
lifts out of the Rockies and into the Plains. NBM PoPs are beginning
to increase for this upcoming weekend in response to the stormy
signal. Unfortunately, P-type issues are likely given the
potentially dynamic nature of this system. What`s important is not
any one specific model run, but the consistency in the signal for a
storm. This should support a greater potential for beneficial
precipitation across the region as we end March.
&&
.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1231 AM CDT Mon Mar 18 2024
Current TAF trends look good. Sites are going to spend much of
the night with BKN stratocu between 4k and 5k feet. These clouds
could produce some flurries, but no impact to visibility is
forecast. These clouds will clear out Monday morning, but be
replaced by a batch of mid level clouds Monday afternoon.
Tonight, we`ll lose gustiness, but we won`t have a period where
we lose the winds. We`ll see a sfc high shift to the east and
return flow set up across the region on Monday. Our winds will
be trending toward westerly and eventually WSW by Monday
afternoon. There will be potential for LLWS as a frontal
boundary pushes through Monday night.
KMSP...Given the forecast wind direction, cross winds will
begin appear in about 18 hours. Some gusts into the low 20s
will be possible with these cross-winds as well. We`ll have to
keep an eye on the possibility for a period of LLWS Monday
night after 04z.
/OUTLOOK FOR KMSP/
TUE...VFR. Wind NW 20G35kts.
WED...VFR. Winds NW 10-15G20kts.
THU...IFR/-SN likely. Some accumulation likely. Wind E 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
&&
$$
DISCUSSION...BPH
AVIATION...BPH