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Area Forecast Discussion (AFD)

Issued by Aberdeen, SD (ABR)

FXUS63 KABR 231739 AAC

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
1239 PM CDT Tue Oct 23 2018

Issued at 1236 PM CDT Tue Oct 23 2018

Aviation discussion updated below for the 18Z TAFs.

UPDATE Issued at 1017 AM CDT Tue Oct 23 2018

Forecast for the rest of today is on track and no changes needed
at this time. With cool high pressure in place and slowly moving
east, highs will be a bit cooler than what we saw on Monday. Winds
will remain light over eastern portions of the forecast area,
while central SD develops breezy southeast winds by this
afternoon. Skies will remain sunny.


.SHORT TERM...(Today and Tonight)
Issued at 304 AM CDT Tue Oct 23 2018

Another dry and sunny day is on tap for the region as s/w ridge 
continues to build into the region. Temperatures remain the biggest 
challenge. For the last few days we've been under forecasting high 
temperatures. Feel that may be the case again today, given LL 
thermal progs off 00z model runs. Biggest issue arguing against 
raising temps significantly above guidance is that LL winds will 
gradually favor southeast, which typically doesn't allow for the 
best mixing.  That said LL lapse rates should be steep up to H9 or a 
bit higher...so, went with the warmest guidance we have, and added a 
couple degrees here and there. For tnt, LLJ kicks in and keeps 
temperatures from falling off too much.

.LONG TERM...(Wednesday through Monday)
Issued at 304 AM CDT Tue Oct 23 2018

Models are beginning to show a wetter pattern during the long term 
portion of the forecast. The period begins with an upper level 
trough slowly crossing the region with rain possible, mainly 
Wednesday afternoon through Thursday afternoon. The climatology 
calibrated precipitation analysis is showing a high probability of 
seeing measurable pcpn, greater than 50 percent. Rainfall amount 
should range below a quarter of an inch for most locations. There is 
a low probability, 10 to 20 percent of seeing amounts 0.4 inches. 

After a brief dry period Thursday night into Friday morning, an 
upper level shortwave could traverse southeastward across the area 
Friday afternoon through Friday night. This system could bring light 
pcpn, but also gusty northwesterly winds. Another upper level 
shortwave could progress across the region on Saturday night. 
Precipitation chances are best in North Dakota with this system.

Models diverge early next week with the GFS showing a large scale 
storm system impacting the region by Tuesday. The ECMWF shows mostly 
a passing wave. Climate signals, negative WPO and EPO do support a 
colder time period around Halloween.


.AVIATION...(For the 18Z TAFS through 18Z Wednesday Afternoon)
Issued at 1236 PM CDT Tue Oct 23 2018

VFR conditions will prevail through the TAF forecast period. LLWS
is likely to affect KPIR overnight and have included mention of
that in the TAF. May see some -SHRA move into KPIR/KMBG late in
the TAF forecast period, and beyond 18Z Wed. Although, conditions
are forecast to remain VFR within any -SHRA.