Area Forecast Discussion
Issued by NWS Twin Cities, MN

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864
FXUS63 KMPX 201211
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
711 AM CDT Sat Jul 20 2024

.KEY MESSAGES...

- Multiple rounds of isolated showers & thunderstorms continue
  through this weekend. Slow-moving storms mean localized
  rainfall nearing an inch.

- Diurnally-driven afternoon showers and thunderstorms are
  likely through midweek, with the best chances for widespread
  rain coming Tuesday night into Wednesday morning.

&&

.DISCUSSION...
Issued at 346 AM CDT Sat Jul 20 2024

Current surface observations showing multiple sites reporting
areas of fog early this morning. Temperatures currently in the
mid to upper 60s with calm winds. Areas of fog are expected to
mix out by mid-morning. As for today`s forecast, a slow moving
lobe of vorticity aloft coupled with a surface low that will
advance across southwestern MN. Enough support is in place this
morning to generate a few isolated showers and potentially a few
rumbles of thunder given ~300 J/kg of MUCAPE in RAP forecast
soundings. The more favorable environment for this morning`s
rainfall is across the I-90 corridor. However, the western
periphery of a cold front is currently draped over NE MN and N
WI. this frontal boundary is progged to sag southward over the
upper Great Lakes region this evening. As this occurs, the lob
of remnant vorticity may encourage redevelopment for convection
across much of MN and western WI this afternoon and evening.
Sunday looks to be a repeat of today in terms of precip
potential given QPF still looking to range between a couple of
tenths to a half inch with a few isolated ares across southern
MN exceeding a half inch. In summary, it will be best to
consider bringing the umbrella if you have outdoor activities
planned.

By the beginning of next week, the cold front departs to our west
however a stagnant summertime airmass will remain in place. This
will allow for daily isolated chances of shower and thunderstorms
each afternoon through midweek. Tuesday into Wednesday continue to
look favorable for more likely bouts of rain. Timing for this
shortwave will be key with regards to storm intensity. Should the
system move through earlier in the afternoon or evening, heavier
rainfall and strong thunderstorms will grow increasingly possible.
Temperatures for the week trend gradually upward into the low
to mid 80s by next weekend.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 625 AM CDT Sat Jul 20 2024

Tricky set of TAFs due to low confidence of afternoon convection
and the potential for IFR-or-worse fog prior to daybreak Sunday
morning. Short-term models have done a poor job of initializing
precipitation this morning and also have poor agreement on the
evolution of any convection this afternoon-evening. While there
is some potential for TSRA this afternoon, which leads to no
more than a PROB30 mention, confidence is low on the placement
of TSRA other than broadly saying central-southern MN into
far western WI. Have brought conditions down to MVFR with any
convection otherwise mainly VFR conditions with light winds will
prevail. Overnight, plenty of low level moisture with calm winds
will be conducive to fog development prior to daybreak, possibly
under 1SM in spots.

KMSP...Kept small chances for TSRA going for mainly the 20z-23z
timeframe, although SHRA could be possible before that. MVFR
conditions are the most likely with any precipitation but IFR is
possible. Fog overnight still looks to impact MSP prior to
sunrise and last through the morning push, with MVFR ceilings
potentially lasting to midday. Additional rounds of SHRA/TSRA
are possible Sunday afternoon so this may be addressed in later
TAFs.

/OUTLOOK FOR KMSP/
MON...VFR. Chc PM TSRA/MVFR. Wind variable less than 5 kts.
TUE...VFR. Chc PM TSRA/MVFR. Wind W to NW 5 kts.
WED...VFR. Wind N 5-10 kts.

&&

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

&&

$$

DISCUSSION...Dunleavy
AVIATION...JPC