Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 270444

Area Forecast Discussion
National Weather Service Topeka KS
1144 PM CDT Fri May 26 2017


.SHORT TERM...(This evening through Saturday)
Issued at 324 PM CDT Fri May 26 2017

Tonight high pressure will gradually settle southeast over the area
with drier air moving south out of Nebraska this evening. Overnight
convection that develops in the Western High Plains with southeast
upslope flow is forecast to move off the high plains and gradually
move east overnight. Models differ with the storms with the NAM
moving a small complex across southern Nebraska late tonight while
cams diminish the convection as it moves east into central Kansas
after 06Z. Low level jet remains across western Kansas overnight so
convection should diminish as it runs into drier air across eastern
Kansas as soundings show drying around 850 mb. Lows tonight should
cool back into the lower 60s.

Saturday will be interesting with the set up for severe storms.
Models differ with amount of morning convection from decaying MCS
with best pops remaining near the Nebraska border. In the afternoon
a surface low will move into north central Kansas by 18Z with a warm
front lifting to around interstate 70 and a cool front extending
southwest from the low into southwest Kansas. The airmass across
eastern Kansas is forecast to become very unstable in the afternoon
hours with cape increasing to around 4000-5000 J/kg, 40 to 50kts of
effective shear and steep mid level lapse rates. Cap weakens in the
afternoon hours allowing for convection to develop. Storms that
develop will have the potential to produce large hail up to the size
of tennis balls with lower potential for damaging wind and an
isolated tornado. Temperatures will warm into the mid 80s ahead of
the front and reach the 70s in north central Kansas.

.LONG TERM...(Saturday night through Friday)
Issued at 324 PM CDT Fri May 26 2017

By Saturday night, the deep mid-level trough will be tracking
eastward across the CWA, which will help to push the surface cold
front east of the area by late evening.  As a result, showers and
thunderstorms will continue along and behind this cold front across
eastern KS before drying out overnight Sunday morning.

Surface high pressure will quickly spread eastward across the
central U.S. Sunday and Monday behind this exiting system, resulting
in dry conditions for the remainder of the Memorial Day holiday
weekend.  Models show the broad mid-level trough remaining anchored
across most of the northern and northeastern U.S. into early this
week.  Despite northwesterly flow aloft remaining in place over the
region, do not expect CAA so have high temperatures staying in the
upper 70s to low 80s with lows in the 50s.

The weather pattern becomes more unsettled Tuesday through the
remainder of the week as a frontal boundary lifts northward into the
CWA on Tuesday and stalls out over, or at least nearby, the forecast
area.  With this stationary boundary present through late week, have
scattered PoPs in place mid-week with increasing PoPs by late week.
Temperatures look to remain fairly steady through the week with
highs remaining in the upper 70s/low 80s and lows in the 50s/low


.AVIATION...(For the 06Z TAFS through 06Z Sunday)
Issued at 1144 PM CDT Fri May 26 2017

The models have continued to show some variability in the
evolution of storms through the day Saturday. In particular the
HRRR has backed off on bringing a linear MCS through the area
early in the day. However the convective allowing models don`t
have the greatest handle on the current convection in western KS.
With models showing a southerly low level jet and isentropic lift
across central KS confirmed by area profiler data, am inclined to
expect storms to hold together and enter the forecast area by mid
morning, even with the latest HRRR casting some doubt. However
uncertainty precludes a more specific forecast for timing in the
terminals. So I still have a VCTS for the most likely window.




LONG TERM...Hennecke
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