Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 151149

Area Forecast Discussion
National Weather Service Omaha/Valley NE
549 AM CST Mon Jan 15 2018

.SHORT TERM...(Today through Wednesday)
Issued at 301 AM CST Mon Jan 15 2018

...Dangerously cold wind chills through Tue morning...

A short-wave trough and attendant jet streak over the northern
High Plains early this morning will progress into the central
Plains today into tonight within the western semi-circle of a
deep-layer cyclone over the upper Midwest. Large pressure/height
gradients on the backside of the upper Midwest cyclone will
translate to blustery northwest winds today, which in turn will
promote continued low-level cold advection. And despite some
sunshine, the cold advection and light snow cover will result in
falling temperatures through much of the day. When coupled with
the gusty northwest winds, afternoon wind chills of -20 to -25 are
anticipated over northeast NE with -15 to -20 elsewhere across
the forecast area.

Tonight, subsidence in the wake of the northern High Plains
disturbance mentioned above will allow a 1050 mb surface high to
build into central parts of SD and NE by 12z Tuesday. Latest model
guidance suggests that surface winds will remain northwest at 10
to 15 mph and clouds will tend to increase, both of which will
limit radiational cooling potential. As such, we have trended
warmer with overnight lows with values ranging from around -10
near the SD border with -6 to -8 across much of the remainder of
our area. Nonetheless, wind chills will be dangerously cold with
readings of -25 to -30.

Tuesday, we remain in the grips of the arctic air mass with highs
in the single digits. Winds will not be as strong as Mon/Mon night
owing to the proximity of the surface high with afternoon wind
chills recovering into the single digits below zero.

By Wednesday, building mid-level heights and a southwest to west
low-level wind component will aid in the erosion of the cold air
mass with afternoon highs warming into the 20s.

.LONG TERM...(Wednesday night through Sunday)
Issued at 301 AM CST Mon Jan 15 2018

A westerly downslope wind component will persist across the mid-MO
Valley through the remainder of the work week, supporting dry
weather with highs in the mid 30s to lower 40s on Thu and 40s on
Fri. We continue to see a signal in medium-range guidance that a
major trough will move through the Great Plains next weekend.
Specific details regarding precipitation type and amounts remain
uncertain, but it is certainly a situation worth monitoring.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 545 AM CST Mon Jan 15 2018

Closed upper low over the western Great Lakes region at 12Z will
track southeast through the period and be over lower Lake Michigan
by Tuesday morning. Area of clouds over Minnesota will spread
south within the circulation of the low with vfr cigs possible by
00Z at all three sites. Gusty northwest winds are also expected as
arctic high pressure builds south into Nebraska during the period.


NE...Wind Chill Advisory until noon CST Tuesday for NEZ034-042>045-

     Wind Chill Advisory from 5 PM this afternoon to noon CST Tuesday
     for NEZ065>068-078-088>093.

     Wind Chill Advisory until noon CST Tuesday for NEZ011-012-

IA...Wind Chill Advisory until noon CST Tuesday for IAZ055-056-069.

     Wind Chill Advisory from 5 PM this afternoon to noon CST Tuesday
     for IAZ079-080-090-091.

     Wind Chill Advisory until noon CST Tuesday for IAZ043.



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