Weather

066 
fxus63 kabr 211958 
afdabr 


Area forecast discussion 
National Weather Service Aberdeen South Dakota 
258 PM CDT Thursday Aug 21 2008 


Short term...tonight through Saturday night 
strong system per models and recent satellite pictures is punching 
into and through the northern rockies with an associated 100kt+ jet 
maximum. Synoptic scale lift should spread out across western North 
Dakota this evening as left exit region of jet maximum enters the 
area. Meanwhile...surface front will also begin surging east as 
pressure rises increase under confluent flow aloft Post jet maximum. 
Ahead of the front winds will remain somewhat of an issue into the 
evening hours. In the last hour surface winds have begun pegging 
advisory criteria at most ASOS locations. Will wait till last 
minute to decide on Wind Advisory for the evening hours. 
Thunderstorm potential ahead of the boundary does not look too 
impressive across County Warning Area. There is a fair amount of surface based 
cape across the region...but convective inhibition remains quite 
high under very warm thermal ridge aloft. And models indicate that 
the thermal ridge will only intensify just ahead of the boundary tonight. 
Nonetheless strong low level jet and some surface convergence ahead of front 
could spark an isolated storm...so will maintain slight chance 
probability of precipitation for northern County Warning Area...which is Colorado-located with strongest 
synoptic scale lift. In accordance with the pop...confidence is 
low that there will be any measurable rain over the forecast area 
tonight. Front blows through early on Friday with much drier and 
somewhat cooler air for the rest of the weekend. Mav guidance 
looked okay with a few tweaks...especially to afternoon 
highs...which is where that particular guidance has had a recent 
warm bias. 


Long term...Sunday through Thursday 
models are in a fair agreement throughout the extended. The period 
opens with a weak middle/upper level trough in the eastern Continental U.S. And 
ridge over The Rockies. This leaves the area under northwest flow 
aloft. At the surface...a large area of high pressure virtually 
dominates the Midwest. The high slowly moves eastward which allows 
for return flow into the central and northern plains. Have 
introduced slight probability of precipitation across the southwest portion of the County Warning Area 
Sunday night through Monday night as models indicate a Theta-E 
ridge...along with ml convective available potential energy above 1500 j/kg. However...am a bit 
concerned with the amount of moisture advection as guidance dew 
points are shown in the middle to upper 50s. The middle/upper level 
ridge begins to breakdown towards the middle of the week as an 
trough pushes through The Rockies. Due to model uncertainty...have 
adjusted HPC guidance with the regards to a middle/upper level trough 
and surface cold front the is expected to swing through the area 
by the end of the work week. 


&& 
Aviation... 
gusty southerly winds can be expected at all terminals through 
this evening. Winds are expected to range from 20 to 30 miles per hour with gusts 
up to 35 miles per hour. Winds will diminish some during the overnight hours. A 
cold front will move across the state Friday morning with winds 
shifting to the west at kpir and kmbg by 12z. Kabr and Katy will 
quickly follow. Wind will be gusty tomorrow afternoon. Katy may 
experience MVFR conditions with ceilings at or above 2k feet. Otherwise visby and ceilings are 
expected to remain VFR through this evening and into tomorrow. 
&& 


Abr watches/warnings/advisories... 
South Dakota...none. 
Minnesota...none. 
&& 


$$ 
Short term...tdk 
long term...South Dakota 
aviation...South Dakota 


Weather.Gov/Aberdeen