Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 171438
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
938 AM CDT Tue May 17 2022

.UPDATE...
Issued at 929 AM CDT Tue May 17 2022

Forecast on track with some light rain showers gradually moving
into the FA this hour. Webcams and surfaces observations depict
high ceilings with cloud bases generally at or above 8000ft
causing virga in the near surface dry layer. Light amounts
continue to be expected with totals less than a tenth of an inch.


UPDATE Issued at 722 AM CDT Tue May 17 2022

Light showers =re slowly moving into our far west this morning,
and this matches the timing of the slight chance PoPs from the
earlier morning update. There is still enough dry/stable air in
place that this activity may struggle to hold together or only
remain isolated in nature as it progresses eastward through the
afternoon.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 322 AM CDT Tue May 17 2022

Impacts in the short term period are related to potential lighter
showers or isolated thunderstorm activity, with severe thunderstorms
not anticipated at this time.

A series of progressive waves within westerly flow aloft are shown
to move across the region today through Wednesday, with the stronger
of these waves centered over southern Manitoba Wednesday. Weak
convergence along surface troughs may aid in initiation of showers or
thunderstorms, but overall chances locally are limited through this
evening due to weaker forcing and instability in our area. There may
be just enough forcing and instability to support isolated to widely
scattered lighter showers and a few weak thunderstorms. On Wednesday
we are on shown to be on the southern extent of the mid level
shortwave with enough forcing for more organized showers/embedded
thunderstorms along the International Border into northwest MN.
Profiles also show potential for a bit more instability (roughly 500-
700 J/KG ML CAPE) and this could support better potential for
embedded thunderstorms maybe an isolated strong storm. Effective
shear isn`t as favorable further north where precip signal is
favored and lowers confidence some (would depend on location of
initiation). Mixing heights are a bit higher, so outside of
convective showers or thunderstorms there would be some
evaporative processes limiting lighter precip reaching the
surface. Precipitation amounts during these periods should be
light (mainly under 0.1") with a 20% probability for 0.25" or
higher along the International Border Wednesday (based on NBM).
HREF does show some potential for totals as high as 0.5" but this
is likely related to thunderstorm activity Wednesday (0% probs for
1" between HREF/NBM).

Regarding temperatures/winds/RH: Relatively seasonal temperatures
are expected in the 60s today and maybe the mid 70s. Increased mixed
layer does raise the potential for gustier winds especially
Wednesday, with peak mixed layer winds from BUFKIT momentum transfer
in the 33-35kt range (sub advisory but still breezy). RH values may
be lowest this afternoon in our east (30-35%) where winds should be
lighter (under 15 mph). RH values recover as Tds increase with the
building low pressure Wednesday, though I could see southern
locations maybe falling the upper 30% range due to better mixing.

.LONG TERM...(Wednesday night through Monday)
Issued at 322 AM CDT Tue May 17 2022

Zonal flow sets up a series of waves moving across southern Canada
and the northern tier for the mid-week period, with the upper level
pattern transitioning to SW flow as a deepening upper low moves from
southern British Columbia into southern Saskatchewan by mid-day
Thursday. A plethora of Pacific moisture will move across the NW
CONUS in the zonal flow with two low pressure systems moving through
(first in the short term) bringing rain to our northern zones. This
is expected to enhance the ongoing flooding impacts on rivers and
agriculture over northeastern North Dakota and the northern valley.

The second low to move across the north begins to spread
precipitation into eastern North Dakota during the day Thursday,
with the surface low beginning to slide NW-SE across the CWA,
setting up a prolonged period of rain across the northern half of
the CWA. Latest GEFS probability of exceedance products show around
a 30 percent chance of exceeding 1 inch of QPF across the northern
half of the CWA (basically along and north of Highway 200). This is
for the 06Z Thursday to 06Z Friday 24-hr period. The same period
shows about an 80 percent chance of exceeding one-half inch. Given
the antecedent conditions across northeastern North Dakota (flooded
rivers and overland flooding), this will further increase impacts
across the north. WPC Excessive Rainfall Outlook has upgraded area
to a slight risk of exceeding flash flood guidance, which I fully
support given the saturated nature of the area from rainfall this
spring. To the southeast, there continues to be a threat for some
severe storms vcnty of the warm frontal boundary as 45 to 50 kt bulk
shear moves across the southern valley into west central Minnesota.
Consequently, SPC has issued a marginal risk for this area.

Following this system, below normal temperatures filter in for the
remainder of the period, with continuing showers bringing a wet and
chilly Friday to end the week. There has been some signal for some
mixed precipitation across the north on Friday, but given ground
temperatures and expected air temperatures, no winter type impacts
are expected as any flakes that fall will melt on contact.

A dry but cool weekend with highs in the 40s will be followed by
another chance for rain showers on Monday, as the next upper wave
moves along the zonal flow aloft and crosses the northern tier.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 636 AM CDT Tue May 17 2022

VFR conditions are expected through most of the TAF period,
though there may be MVFR ceilings bringing to develop into
northeast ND towards the end of the TAF period (currently favored
after the current period). Light east-southeast winds eventually
increase in eastern ND and KTVF with


&&

.HYDROLOGY...
Issued at 336 PM CDT Mon May 16 2022

Long duration, significant riverine flooding will continue over the
next seven days for numerous locations along the Red River and its
tributaries within eastern North Dakota into northwest and west-
central Minnesota. In addition to riverine flooding, overland
flooding resulting in road closures and washouts still persists
across portions of northeast North Dakota even well after the
responsible rainfall has ended. Overland flooding is also impacting
area agriculture in addition to impact to travel, specifically
delayed planting activities. Notable signatures indicating overland
flooding away from rivers are evident in recent satellite imagery
including Sentinel-2 and VIIRS/ABI flood extent products.

After a dry Monday and Tuesday, precipitation chances increase yet
again Wed - Fri. While Wed should see scattered shower activity
yielding little precip, Thu - Fri should see widespread
precipitation with at least 0.50 inches likely, possibly exceeding 2
inches in some locations. This will likely impact rivers in some
way, although to what degree and location is uncertain at this time.
Additionally, overland flooding may redevelop and/or worsen in some
locations that see highest amounts closer to 2 inches.

The current river forecasts account for observed precipitation as
well as forecast precipitation over the next 24 hours. They do
not include the the Wed - Fri precipitation. Thus the forecasts
are likely to change as they account for this upcoming event`s
precipitation.

Red River mainstem...

Minor to major flooding is ongoing and/or forecast for the mainstem
Red River. Highest river levels reside in the northern Valley with
Pembina and Drayton remaining within or near major flood stage
through the next seven days. Oslo has finally dropped out of major
flood stage and is expected to slowly decrease through at least mid
week.

This week`s precipitation will likely impact rivers in some way,
although to what degree and location is uncertain at this time.

Minnesota tributaries...

Most Minnesota tributaries have crested or are near crest. Minor to
moderate flooding mainly resides near the mainstem Red River.

This week`s precipitation will likely impact rivers in some way,
although to what degree and location is uncertain at this time.

North Dakota tributaries...

While most North Dakota tributaries have crested, the Sheyenne River
continues to remain focus with river levels between moderate and
major flood stage. The Sheyenne River at Kindred and Harwood as well
as the Diversion at West Fargo will remain in moderate to major
flooding through the next seven days. Sentinel-2 satellite imagery
shows breakout water near the Sheyenne, Maple, and Red rivers
confluence further up the Sheyenne River to near Kindred. Along the
Pembina River, the persistent flood wave is showing signs of ending,
at least temporarily pending upcoming precipitation. Neche has
dropped below flood stage, but again satellite imagery and area
reports indicate backwater and breakout water issues closer to the
mainstem Red River still persists.

This week`s precipitation will likely impact rivers in some way,
although to what degree and location is uncertain at this time.

&&

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

UPDATE...JK
SHORT TERM...DJR
LONG TERM...Speicher
AVIATION...DJR
HYDROLOGY...CJ


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