015
FXUS63 KFGF 181749
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1249 PM CDT Tue Jun 18 2024

.KEY MESSAGES...

- Isolated strong thunderstorms are possible during the midday
  to early afternoon hours, primarily in portions of west
  central Minnesota.

- Additional chances for thunderstorms and heavy rain are
  possible late Thursday through early Saturday.

&&

.UPDATE...
Issued at 1248 PM CDT Tue Jun 18 2024

At noon the surface low was located over east central South
Dakota, with a warm front extending out to the northeast,
clipping our far southeast FA (Elbow Lake to Wadena). Elbow Lake
had risen to 74F with a dewpoint of 70F. Not too far south of
this area, temperatures were in the low 80s with low 70s
dewpoints. Due to the big northwest to southeast thermal
gradient, the CAPE gradient was huge too. The 0-6km effective
shear still looks to be around 40 knots in our southeast FA,
with the 0-3km bulk shear about the same. Glancing at some of
the tornado parameters on the SPC meso page, seeing the higher
values just to the south of this FA, but some of our counties
still remain on the gradient, including Grant, Otter Tail, and
Wadena. Just got a Mesoscale Discussion from SPC, who are
monitoring this area for a Tornado Watch. If one is issued, only
expect a window for our southeast FA until about 4 or 5 pm.

UPDATE
Issued at 1002 AM CDT Tue Jun 18 2024

The surface boundary currently extends from Roseau to Hawley
(Minnesota) back toward Gwinner North Dakota. Ahead of this
boundary, temperatures were in the mid to upper 60s, with
dewpoints in the low to mid 60s, and southeast winds. Behind the
boundary, temperatures were in the low 50s with similar
dewpoints, and winds were from the north. Webcams and surface
observations showed some fog from Devils Lake to Valley City and
Gwinner, so went ahead and added that mention through the rest
of the morning. There were still elevated showers and
thunderstorms along the boundary, mainly from Forman to Wahpeton
to Bemidji. Here there was still some focus from the low level
jet, some elevated instability, and fairly strong 0-6km
effective shear. SPC still has a slight risk for severe storms
brushing our far eastern FA today, which is pretty well matched
by WPC with a slight risk for excessive rainfall. The latest 12z
HREF UH tracks still match this SPC area, so will have to keep
an eye on a few more strong to severe storms from late morning
through the afternoon. So far, it looks like it may be hard to
develop much instability with all the clouds.

UPDATE
Issued at 659 AM CDT Tue Jun 18 2024

Severe thunderstorm activity is now east of the area this
morning, with widespread light to moderate rain persisting from
the Red River Valley eastward. The heaviest rain is currently in
Otter Tail and Grant Counties, and slowly moving to the
northeast.

&&

.DISCUSSION...
Issued at 350 AM CDT Tue Jun 18 2024

...Synopsis...

Southwest flow continues across the Northern Plains and Upper
Midwest, with deep H5 troughing across the Pacific Northwest and
strong H5 ridging over the Eastern CONUS. Ensemble guidance is
somewhat consistent in weakening the eastern ridge very slowly over
the course of the next week or so; however, the timing of this
weakening will strongly determine what impacts we can expect as we
head into the weekend. There is a continued signal for heavy rain
and perhaps a few strong thunderstorms across a good portion of
southeastern North Dakota and west-central Minnesota as another
shortwave develops later this week.


...Scattered Severe Thunderstorms This Morning...

Severe thunderstorm chances will diminish from west to east this
morning, with most of the risk pushing east of the forecast area by
around 8am. Primary impacts will be in the southern Red River Valley
and west-central/northwest Minnesota, and will include thunderstorm
wind gusts as high as 60 mph.


...Moderate Rain Diminishes Slowly Today...

Periods of moderate rainfall have been following a line of storms
through much of the morning. For the Red River Valley westward, most
shower activity is expected to end by around midday; however, points
east could see moderate rain persist into the middle to late
afternoon hours before pushing off to the east.


...Active Pattern Continues Thursday through Saturday...

After a period of relatively quiet weather Wednesday and early
Thursday, another system is expected to bring additional rain and
thunderstorm chances to the area late this week and into the
weekend. The position of the H5 ridge will ultimately determine how
much moisture will be able to work into the Northern Plains, with
most ensemble members showing the potential for mixing ratios
exceeding 12 g/Kg. If the ridge weakens, we would see lower
potential moisture; however, clusters slightly favor a stronger
ridge, which would allow a more direct moisture fetch out of east
Texas. Current probabilities are highest across southeastern North
Dakota and west-central Minnesota, where there is an 80 percent
chance to see 0.50 inch or more rain late Thursday through early
Saturday. Thunderstorm potential exists; however, there is a large
degree of variability in model sounding output at this time. Most
guidance allows for at least a mention of a few elevated storms
capable of reaching minimal severe limits.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1248 PM CDT Tue Jun 18 2024

The low clouds and patchy fog are making the aviation forecast
tricky. Although there are still a few sites reporting fog, for
the most part think the fog should be about done. That will not
be the case for the low clouds. Models are holding these over
the area at least through the rest of the day and into tonight.
Think any remaining thunder threat should only affect KBJI for
another couple of hours. Wind should remain from a northerly
direction, with speeds mainly in the 10 to 15 knot range.

&&

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

&&

$$

UPDATE...Godon
DISCUSSION...Lynch
AVIATION...Godon