Area Forecast Discussion
Issued by NWS Aberdeen, SD

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FXUS63 KABR 201632 AAB

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1032 AM CST Mon Nov 20 2017

Issued at 1026 AM CST Mon Nov 20 2017

Pretty thick cirrus shield moving east across the area this
morning. Satellite trends show thinning/clearing moving into
western areas now, but it looks rather brief as another thick
shield is moving out of western ND and eastern MT. This quite
possibly could keep high temps down a few degrees from forecast
highs. Will continue to monitor trends and may have to make
adjustments yet this morning. Otherwise, had already increased
winds today, more so for central SD where mixing potential looks


.SHORT TERM...(Today through Wednesday Afternoon)
Issued at 327 AM CST Mon Nov 20 2017

Low pressure currently across southern Saskatchewan will shift to
southern Manitoba this afternoon, and exit across southern Ontario
this evening. Cloud cover remains tricky early this morning, with
thin high clouds streaming in from the northwest. Thicker clouds
were evident over eastern MT/WY, which will impact our western
counties closer to 00Z. Temperatures will be around 20 degrees above
normal for this time of year, topping out in the mid 50s to low 60s
today. Relative humidity values will fall to 20 to 30 percent.
Combined with 10 to 15 mph winds out of the west, the dry and warm
conditions will result in elevated grassland fire danger over
portions of central South Dakota.

A strong cold front will drop south through the area this evening
(sinking south of the ND/SD border already prior to 00Z). Behind the
front, expect breezy northwest winds and cooler air. Highs Tuesday
will only be in the 20s to around 30 degrees. Winds will be out of
the northwest gusting 25 to 35 mph, strongest over eastern South
Dakota and western Minnesota as the pressure gradient tightens
between the exiting sfc low and western Canadian high pressure
building overhead.  The sfc high should stretch from southern
Saskatchewan through ND and eastern SD by 00Z Wednesday. The result
will be quickly diminishing winds late Tuesday afternoon. The cold
snap will be brief, with another warm up in store for the second
half of the work week. The sfc high will sink across eastern NE/KS
already by 06Z Wednesday, with a ridge remaining over our forecast
area. The ridge will swing into MN by 12Z Wednesday, setting the
stage for increasing southerly flow. Temperatures over
Stanley/Jones/Lyman counties should get into the mid-upper 50s. It
will be an impressive temperature gradient, with highs only in the
low 30s over northeastern SD/western MN. Still keeping the slight
chance/low chance pops for our northeastern counties Wednesday
afternoon. While most models do show some sort of precipitation, it
all looks to be light mix of mainly snow, mixing with or
changing over to rain and/or drizzle.

.LONG TERM...(Wednesday Evening through Sunday)
Issued at 327 AM CST Mon Nov 20 2017

Northwest flow aloft and a dry forecast predominates the period.
Briefly Friday morning, the flow flattens as energy diving south-
southeast out of Canada heading for the Great Lakes region knocks
down the western CONUS upper-level ridge. Previously, models were
actually generating a little bit of light qpf with this feature.
This morning, they depict this system as working through the region
basically dry. By Friday evening, the heights aloft are rising out
west again. Notably warm air is still trying to work over into the
northeastern corner of the forecast area at the start of the period.
Models/ensembles still depict much above normal warm airmass in
place heading into Friday when the next cold fropa is progged for
this cwa, signaling a pendulum swing back into some colder air over
the weekend.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 455 AM CST Mon Nov 20 2017

Good VFR is expected over the next 18 hours. There`s a small
chance of stratus moving south into the region by Tuesday morning.




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