320
FXUS63 KFGF 151100
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
600 AM CDT Thu Aug 15 2024

.KEY MESSAGES...

- Locally heavy rainfall will continue into the early morning
  hours within the northern Red River Valley

&&

.UPDATE...
Issued at 600 AM CDT Thu Aug 15 2024

The steadiest rain continues to fall over the central and
northern Red River Valley, and it appears it is now filling back
in over the northern Devils Lake region. Therefore have
increased precipitation chances in these areas to about 100
percent. 24 hour rainfall totals in some areas are approaching
2 to 3 inches. Still seeing some fog in the western Devils Lake
region as well, but it remains patchy with up and down
visibilities.

&&

.DISCUSSION...
Issued at 306 AM CDT Thu Aug 15 2024

...Synopsis...
There is quite an extensive ongoing area of rain across the
Northern Plains at the time of this discussion. In this FA
specifically, can see a nice spin in the precipitation from the
Mayville radar, seemingly centered just east of the Fargo
Moorhead area. Per the SPC mesoanalysis page this is where a
nearly stacked low pressure system is. This system has really
slowed down from what had been seen the past few days, with this
low now expected to slowly spin right over the FA all day. It
should finally begin to push eastward tonight into early Friday.
This system should still be followed by 500mb ridging for the
weekend into early next week. How this ridging may break down
in the mid to late week period is still quite uncertain.

...Locally heavy rainfall early this morning...
As the above mentioned low has set up over the central Red
River Valley early this morning, there is also an inverted
trough north of the low extending up into northeast North
Dakota. Precipitable water values are still around 1.80 inches
within this corridor of strong 850mb moisture transport. Since
midnight, have seen the steady rain across southeast North
Dakota end, with the comma-shaped current band taking shape over
the central and northern Valley. Big drops of rain falling
quickly have led to precipitation amounts exceeding 2.00 inches
within a narrow corridor around Grand Forks. This has fallen in
waves, and Grand Forks has been dry, which has slowed the runoff
from this rain. Interesting as well, there has been no lightning
with this rainfall. These echoes continue to progress
northward, and will move into the northern Valley between now
and sunrise. Therefore it is likely the northern Valley will
also see some amounts in the 1 to 2 inch range, although again
these will be fairly localized.

From sunrise through noon, the highest probabilities (70-90%) for
rain will remain north of the highway 2 corridor, and possibly
even transition westward back into the Devils Lake region. Then
the rest of the area should see these higher probabilities for
the afternoon. The best moisture feed will start to get cut off
though, so outside of any thunderstorms, rainfall rates will be
lower than now. It does look to stay cloudy all day today, so
not sure how much instability will develop again. At this point,
areas along the North and South Dakota border may see a few
breaks, and that may be the only area that could see some
rumbles of thunder this afternoon. As mentioned in the previous
discussion, with the spin in the atmosphere, funnels may be
possible this afternoon. This will be less likely without some
heating (clearing), so will just have to keep an eye on that
through the day. Fog is also something to monitor, but need some
clearing for this too.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 600 AM CDT Thu Aug 15 2024

Tricky set of TAFs as the low pressure system will basically sit
right over the FA today and spin. The highest precipitation
chances will be along and north of highway 2 this morning, then
they will increase about everywhere this afternoon. Have kept
TAFs simple for now, trying to narrow down what is going on
within the first 6 hours. It is going to be rainy and cloudy,
with variable wind directions throughout.

&&

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

&&

$$

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