248
FXUS63 KFGF 110532
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1232 AM CDT Tue Jun 11 2024

.KEY MESSAGES...

- Showers and scattered thunderstorms are expected this evening
  and overnight. The main threat will be lightning.

- Isolated to scattered severe thunderstorms possible Wednesday
  afternoon and evening, especially in west central Minnesota
  and the southern Red River Valley.

&&

UPDATE
Issued at 1022 PM CDT Mon Jun 10 2024

Rain has continued to spread east with reports in the 0.1-0.25"
range where the moderate activity had been tracking in the
Devils Lake Basin. The leading edge of the activity is just now
in the immediate RRV but where lighter returns are activity is
struggling to overcome the low level dry layer at the onset,
which is similar to what we saw happen in the Devils Lake area
before rain finally started. Where moderate returns are showing
up aloft we are starting to see rain (such as here at the NWS
office). The general forecast is on track, so no major changes
during this update cycle.

UPDATE
Issued at 637 PM CDT Mon Jun 10 2024

Rain showers are increasing in coverage across our west with
reports of rain reaching the surface now where returns are
greater than 35dbz on radar, and the activity is filling in
just west of our CWA, matching trends from CAMs/HREF mean.
Saturation of the dry layer should continue as this pushes
east, so while initially there may be virga we are on track for
a swath of light to moderate rain across our forecast area this
evening and overnight. I increased PoPs and adjusted timing to
reflect these trends. Lighting activity has been minimal, and
instability has been limited based on RAP analysis (100 J/kg or
less), limiting thunderstorm potential/impacts. Indications
from CAMs support a consistent 0.1-0.3" rainfall event where
this tracks, though there could be some locations as high as
0.5" (25% chance).

&&

.DISCUSSION...
Issued at 353 PM CDT Mon Jun 10 2024

...Synopsis...

Several troughs and shortwaves are set to traverse the Northern
Plains in the coming days, with the first expected to bring rain and
isolated thunderstorms to the area this evening and tonight. There
will be minimal instability with this first system, with the
expectation of mainly embedded thunderstorms. For Tuesday, lingering
showers and storms move east of the area by around midday, with
shortwave ridging building in from west to east.

...Potentially Strong Storms Wednesday...

Our next trough moves into the area Wednesday following a brief
amplification of an H5 ridge late Tuesday into Wednesday morning.
There are a number of possible scenarios that could unfold Wednesday
with impacts scaling with timing. Most guidance is now bringing the
best forcing through the area very early in the afternoon, which
would still allow for strong storms, but with lower coverage. CAPE
still has at least a 70 percent chance to exceed 2000 J/Kg,
primarily in west-central Minnesota and the southern Red River
Valley. Alternatively, a slower and deeper trough allows the H5
ridge to build into the area and bring additional moisture further
north Wednesday afternoon, thus expanding the area of potentially
severe thunderstorms well into northwest Minnesota and the central
Red River Valley. Shear will be favorable in both scenarios, with
low level (0-3 Km) shear upwards of 20-30 knots, and deep layer (0-6
Km) shear in the range of 50-60 knots. Model soundings have been
consistently showing dry air in the mid levels, both increasing
our lapse rates, and providing a favorable environment for RIJ
development. Overall, this would mainly be a wind threat,
associated with hybrid clusters and possibly line segments;
however, supercells could briefly develop early in the process.

Another shortwave and H5 upper low pushes through on Thursday, with
little instability to work with in the wake of Wednesday`s system.
Look for mainly embedded storms, with the possibility of an isolated
stronger storm during the early to mid afternoon.

&&

.AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 1231 AM CDT Tue Jun 11 2024

Rain continues to move across eastern ND into northwest MN.
Ceilings have remained VFR, but there are indications of MVFR
starting to form in southern Canada. Latest guidance shows a
weaker signal for sub-VFR conditions in ND with VFR now favored
to prevail. NW MN there is still better potential for a period
of MVFR as the rain transitions east and lower level moisture is
shown to pool in the 09-14Z period (KTVF and KBJI impacted).
Winds should increase 12-19kt range with increasing daytime
gusts from the west (highest at KDVL) Tuesday.

&&

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

&&

$$

UPDATE...DJR
DISCUSSION...Lynch
AVIATION...DJR