Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 240435
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
1135 PM CDT Fri Sep 23 2016

.UPDATE...
Issued at 1128 PM CDT Fri Sep 23 2016

Expanded thunder mention into the northern valley otherwise no
significant changes with temperatures or pops.

UPDATE Issued at 927 PM CDT Fri Sep 23 2016

Arc of showers and T continues across north half of the forecast
area in zone of strong warm advection/low level moisture
transport and on nose of 45kt low level jet. T mainly confined to
the DVL basin. Model guidance consistent in gradually lifting arc
northward towards the international border. Adjusted pops
accordingly with no other changes needed.

UPDATE Issued at 625 PM CDT Fri Sep 23 2016

This update adjusted pops based on current and expected radar
imagery using the HRRR which is handling current pcpn positioning
well. Also added fog to the Devils lake basin based on majority
model guidance.

&&

.SHORT TERM...(This evening through Saturday)
Issued at 257 PM CDT Fri Sep 23 2016

Precipitation timing and how strong tomorrow`s convection will be
are the main challenges for the period.

Showers and thunderstorms stretch from northwestern ND into
central MN across our southwestern counties. This activity will
lift north and east throughout the rest of the afternoon into the
evening as isentropic lift along the mid level baroclinic zone
moves through. The main surface warm front is well to our south,
and the model have it moving slightly northward towards our
southern border later tonight. Both the high resolution models as
well as the synoptic runs have the most significant precip along
the mid level front and lifting north towards the Canadian border
throughout tonight. There is some weak elevated CAPE as seen on
the SPC meso page and the models have this continuing so will keep
the mention as showers with isolated thunderstorms. With the warm
front still mostly to our south there will be plenty of cloud
cover overnight and southeast winds will keep us mixed. Have some
mild low temperatures in the 50s to low 60s.

Tomorrow, the main upper low currently over the Rockies will
progress into western ND. The models are in decent agreement at
this point in the forecast and have the surface low moving up into
western to central ND during the day and starting to wrap up.
Southeasterly winds will continue for our area and the tongue of
warmer air will start to move into the southern Red River Valley.
There is still some question how much clearing there will be
during the day on Saturday, with most of the models having quite a
bit of moisture lingering in the area. At this point think there
will be at least some breaks and allow temperatures to get into
the 60s and 70s by afternoon. The NAM has a narrow band of surface
based CAPE moving into our western counties late in the day. Deep
layer bulk shear is better further west, but there could be some
30-40kts of 0-6km shear. Storms should start to redevelop by
afternoon in the western counties into the Red River Valley. Still
a lot of uncertainty, but there is enough CAPE and bulk shear
predicted by the models for a marginal risk tomorrow afternoon.

.LONG TERM...(Saturday night through Friday)
Issued at 257 PM CDT Fri Sep 23 2016

The primary challenge for the long term period will be timing and
placement of the dry slot associated with an area of low pressure
over western North Dakota. GFS and ECMWF are in similar agreement
with 00Z Sunday spatial characteristics of the surface low,
positioned from Sakakawea area to Medora with the ECMWF slightly
southwest at 00Z. However, GFS positions upper low further north.
A band of showers and embedded storms will develop sometime in the
late evening to overnight period. With subtle model differences,
leaning toward SREF solution for timing and placement...which
gives likely POPs over eastern zones and a sharp transition to dry
conds westward into the dry slot. Next challenge becomes track of
upper low and location of the wrap around moisture that should
eventually fill in western and northern zones later in the long
term period. Favored superblend solution for this portion of the
system`s evolution. Throughout the last three shifts monitoring
this system, models have been fairly consistent with no to low
CAPE values for this time period...and have once again revert wx
type grids back to the most likely scenario, predominant rain
showers with small potential for embedded thunder.

After the upper low/trough swings through, northern tier transitions
to NW flow pattern aloft with an amplifying ridge over the Canadian
rockies that slides over the Dakotas by Tue night.  This will bring
dry weather the the middle portion of next week, with fall like
temperatures.  Chances for precip increase again near the end of
next week.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1128 PM CDT Fri Sep 23 2016

Arc of showers and thunderstorms continue to lift north with rain
chances holding on longest in the DVL area. Otherwise MVFR/IFR
cigs lifting through the region with GFK/TVF likely to go down
soon. CIGS to gradually lift tomorrow morning/afternoon.

&&

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

$$

UPDATE...Voelker
SHORT TERM...JR
LONG TERM...Speicher
AVIATION...Voelker


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