Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 200919
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
419 AM CDT Fri Oct 20 2017

.SHORT TERM...(Today through Sunday Afternoon)
Issued at 419 AM CDT Fri Oct 20 2017

A breezy period starts today, and continues off and on through at
least Sunday. The initial breezy conditions will be thanks to the
strengthening pressure gradient between the sfc high over the Mid-
Atlantic states, and the low over southern Canada and Montana.

Very warm and dry today. The lowest RH values will be
west of the Missouri River again, ranging from the upper teens to
around 30 percent. The greatest concern is over Corson County, where
the Rangeland Fire Danger Index will be in the very high category.
However, the strongest winds will be over the eastern half of the
forecast area. With winds hovering around 50kts at 850mb, it won`t
take much to get some gusty conditions at the surface. While we
aren`t expected to tap into those 850mb winds, we should still have
gusts of 30 to near 40mph. Will continue to highlight this in the
HWO. Will also highlight the very high rangeland fire danger index
values for Corson County, and the relatively poor RH recovery
tonight as wind increase overnight.

By 00Z, the sfc low will extend from southern Saskatchewan through
eastern MT and the western ND border. While winds will diminish a bit
in the evening, we will likely still experience downslope winds off
the Sisseton Hills, and then after the passage of the cold front
overnight, a quick change to northwest winds (especially over our
northwestern counties). Highs will only be in the upper 50s to low
60s Saturday, as the cold front brings additional clouds and a
chance of showers through mid afternoon. Thunderstorms can`t be
ruled out, but should mainly stay to our southeast.

Dry weather expected Sunday, with breezy southwest winds returning
as the cold front moves across the Upper Great Lakes region, and a
sfc ridge overhead Sunday morning shifts to our east.





Temperatures/winds/pcpn all factor into forecast challenges through
Saturday. For tonight through Friday, the southerly winds will
continue to usher in increasing warmth and LLM. The higher
dewpoints should effectively limit fire danger on Friday, despite
heftier winds. The increased moisture should also lead to an
increasing chance for weak/elevated convection Friday night as a LLJ
cranks up ahead of an advancing frontal boundary, especially over
the eastern CWA. The front moves east of the CWA Saturday
morning, with cooler air flowing in behind the boundary. However,
on Friday in advance of the front, it should again get quite mild
with temperatures well into the 70s, to around 80 or so for some
locations. LL thermal progs have backed off a bit from previous
runs, but still feel that going forecast is pretty close and
didn`t change much. Temperatures on Saturday will be cooler, but
still above normal for most locations across the forecast area.

Will open with an upper trough/departing shortwave over the central
CONUS, moving east with zonal flow in its wake. A secondary wave
will deepen the upper trough overhead Monday/Tuesday. That will be
followed by a high amplitude upper ridge that is fairly progressive,
with another upper trough diving into the region for Thursday. While
we do see several waves, none feature much of a change for moisture.
However, through next week we should see at least two frontal
passages. The result will be the typical Northern Plains thermal
roller coaster ride. Low level flow is westerly Saturday night
with warm advection leading into Sunday. Mixed winds in BUFKIT
with deep (for this time of year) mixing (to around 800mb) will
result in mild/breezy conditions, though it remains uncertain if
we will fully realize the stronger winds aloft thanks to warm
advection. A front moving through Monday will result in
temperatures dropping off slightly and strong northwest winds. The
coldest air looks to glance the region with another surge in mild
air for mid week. That will be followed by another front and a more
substantial temperature drop late in the work week.


.LONG TERM...(Sunday Evening through Thursday)
Issued at 419 AM CDT Fri Oct 20 2017

A cold front will push through the region Sunday night with a
deeping upper trough settling in behind it. Although it appears that
any associated precip will remain to the north and east, H85 temps
in the negative single digits will nudge as far west as the James
valley on Monday and Tuesday. Highs on Tuesday will only top out in
the 50s which is seasonable for late October, but cooler than the
current October trend thus far. Upper ridging will build back in on
Wednesday helping push temps back up into the 60s. This will be a
brief reprieve as another cold front and upper trough are set to
sweep through at the end of the work week.


&&

.AVIATION...(For the 06Z TAFS through 06Z Friday Night)
Issued at 1208 AM CDT Fri Oct 20 2017

VFR conditions will prevail across the area overnight and through
the day Friday. Look for southerly winds to increase into the 15 to
30 knot range by mid morning and continue into the evening hours.


&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

SHORT TERM...KF
LONG TERM...Wise
AVIATION...Wise


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