939
FXUS63 KFGF 281141
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
641 AM CDT Fri Jun 28 2024

.KEY MESSAGES...

- There is a level 1 out of 5 risk for severe thunderstorms
  across the region today in the late afternoon and evening.

- There is a low chance for severe thunderstorms again Monday
  across the region.

&&

.UPDATE...
Issued at 641 AM CDT Fri Jun 28 2024

Patchy fog has started forming this morning thanks last nights
moisture. There are lingering showers slowly working its way out
of northwest Minnesota. Expecting by this afternoon this fog to
lift or dissipate as we are mixing out. The severe risk still
seems very conditional and heavy rain showers or strong
thunderstorms may still be the more likely scenario.

&&

.DISCUSSION...
Issued at 404 AM CDT Fri Jun 28 2024

...Synopsis...

The wave responsible for last nights showers is moving off to the
east into the great lakes region. The upper level low is currently
on the border of Alberta,Canada and Montana. Convective guidance
shows the low moving directly over the Northern Plains and then
exiting the region via the arrowhead before moving back into Canada
over the great lakes. Starting this afternoon this low is depicted
as entering North dakota from the West and having this narrow band
of instability off the frontal boundary that extends into the
valley. However, the moisture and theta-e axis is being pulled
across the arrowhead potential leaving our area with very little to
lift. Looking at model soundings our mixed layer Cape is around 500
joules which could lead to showers and some pretty lightning bolts
but not really severe. However, the catch is the shear profile ahead
of the low is about 30-40kts which is sufficient to sustain storms
if convection were to initiate. With this upper low passing directly
conceptually we can obtain more forcing and instability ahead of the
low but I`m not quite to sure if we have a long enough
destabilization period to help the dynamics produce more than heavy
showers. The model soundings better support heavy rain but SPC did
keep the marginal risk over the majority of that CWA because of the
low passing through. Because of this going to message severe
potential of quarter sized hail and 60 mph just because if we do
reach a long enough destabilization period then we might hit severe
but another round of heavy rain with lightning is probably more
likely.

...Severe threat Monday....

Another mid/upper wave follows a very similar track and evolution as
the system Friday, with a period of widespread showers or embedded
thunderstorms. There is a signal for a deeper warm sector building
into our region within most clusters, and higher probs for SB CAPE
to exceed 1000 J/KG during the peak heating/diurnally favored period
of the afternoon/evening. CSU GEFS based machine learning (15-30%
severe probs) are supported by 100% chance for greater than 55 NBM
CWASP and 50-60% probability for NBM CWASP values exceeding 65. That
aligns with a threat for isolated to scattered severe convection.
This is still farther out, so details/impacts are still inherently
uncertain.&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1031 PM CDT Thu Jun 27 2024

MVFR to IFR and eventually LIFR conditions expected through
tonight into Friday evening. With the TSRA moving through,
ceilings are forecasted to drop to around 005 into Friday
morning and remain there for the TAF period. Winds will lessen
to around 10 knots, but before then they will be gusting up to
20 - 25kts and sustained around 15 kts. Winds will shift into
Saturday morning, but that is outside the current TAF period.

&&

.AVIATION /12Z TAFS THROUGH 12Z SATURDAY/...
Issued at 641 AM CDT Fri Jun 28 2024

Fog has moved into some of the TAF sites creating a mix between
LIFR,IFR, and MVFR conditions. As we slowly start to mix out
during the day the conditions should rise to MVFR/VFR by 18z.
However by 23z KDVL could start to see some showers from the
start of the next wave. By 03z the Red river valley would then
start seeing those showers. KBJI may start seeing those showers
by 06z. Ceilings are expected to drop back down into the Low
MVFR/IFR category just ahead of those showers.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.

&&

$$

UPDATE...MM
DISCUSSION...MM
AVIATION...MM