Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 250811
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
311 AM CDT Wed May 25 2022

.SHORT TERM...(Today through Thursday)
Issued at 303 AM CDT Wed May 25 2022

500 mb trough/upper low over Oklahoma with flow south to north
into Minnesota. This trough/low will track east the next 24 hours.
Moisture from this system is spreading light rain into SE SD into
southern MN with rain up to Brookings, Canby, Wilmar to Litchfield
MN. But system is moving east so time period for when the moisture
moving north will affect the southeastern fcst area (Fergus Falls,
Park Rapids, Wadena) is rather brief compared to farther east.
Overall guidance has shifted chances for rain farther east with
backedge of any chance from Elbow Lake to Fergus Falls to Bemidji
today. Rain amounts very light trace to a few hundredths.
Considerable high clouds over eastern ND and NW MN with mid clouds
working into WC MN thru dawn.

For today, outside of rain chc in far SE fcst area, a dry day with
thicker cloud cover WC MN and gradually thinning of clouds
farther west and northwest you go. Thus warmest temps today in NE
ND (esp DVL) with 65-70 and coolest temps in WC MN with upper 50s.
SSE winds today most locations in the 10-18kt range.

As system shifts east tonight skies will clear and Thursday looks
like a sunny and warm day with highs upper 60s to mid 70s SSE wind
to 20 kts in E ND.

.LONG TERM...(Thursday night through Tuesday)
Issued at 303 AM CDT Wed May 25 2022


Impacts...

* A more active pattern will return late this week into the weekend
  as southwest flow becomes the flavor of the week.

* Severe thunderstorms do appear possible this weekend, although
  nailing down timing and impacts is difficult to determine at this
  time. Primary hazards appear to be hail and damaging wind gusts.

* Flash flooding is possible this weekend, especially with any areas
  that receive training thunderstorms.

SYNOPTIC ANALYSIS

Ensemble guidance has solid agreement on eventual troughing to our
west and downstream shortwave ridging occurring late this week into
the weekend. There is some difficulties between individual ensemble
members and ensemble clusters for timing and magnitude of the
synoptic pattern, as indicated by EOF clusters. Strength of
downstream ridging will likely play a key indicator in moisture
advection within the lower levels, and subsequently instability and
severe risk. There are hints within individual members of brief
shortwave ridging sometime next week, which may slow down the
activity a bit, but it does appear that general southwesterly flow
will stick around for the entire long term period, meaning multiple
chances for showers and thunderstorms.

SEVERE POTENTIAL THIS WEEKEND...

With the return of southwesterly flow aloft, it does appear like
multiple shots of showers and thunderstorms are likely for the long
term period.

A leading shortwave ahead of the longwave trough will likely bring a
brief period of showers and thunderstorms Friday night into Saturday
morning. How strong instability gets with this shortwave trough/cold
front aloft will depend on location relative to the upper ridge, as
that will play the biggest key in moisture/instability advection. At
this time, it does not appear the location will be favorable for
stronger advection with this shortwave.

The strongest moisture advection surge will likely arrive once
ridging is far enough downstream to support southerly flow within
the lower levels. This does allow for a decent chunk of instability
to arrive over the area, with MUCAPE fields with ensemble guidance
in the range of 1500-2500 J/kg. Thermal wind balance is noticeably
much less, leading to weaker flow across the atmosphere. Because of
the weaker flow, there is some concerns with this potentially
causing isolated areas of flash flooding, particularly where
thunderstorms are able to train along forcing mechanisms. Low level
flow does appear rather weak, so a widespread tornado threat should
be mitigated (but is a non-zero chance). Hail and wind appear like
they will be the greatest threats from this system in addition to
potential isolated pockets of heavy rainfall/flooding.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1046 PM CDT Tue May 24 2022

Rain will continue to lift north across southern MN and into west
central MN by around 6 AM. Mid clouds will begin moving over TAF
sites by noontime, with some low VFR BJI/FAR arriving around noon.
BJI has best chance of seeing MVFR cigs by mid afternoon as rain
should mainly be across west central and north central MN, missing
most of the valley. Have introduced MVFR into BJI TAF.


&&

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

SHORT TERM...Riddle
LONG TERM...Perroux
AVIATION...Speicher


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