Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 180511
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1111 PM CST Fri Feb 17 2017

...AVIATION UPDATE...

.SHORT TERM...(This evening through Saturday)
Issued at 322 PM CST Fri Feb 17 2017

Upper low was observed via water vapor imagery rotating through
Oklahoma, lifting mid level moisture into southeast Kansas. Surface
trough axis shifting east towards the Great Lakes region will shift
gusty southerly winds towards the north after sunset. Ahead of this
weak boundary, temperatures have warmed into the lower 70s while
dewpoints mixed down into the lower 30s. Topeka broke the record
high at this hour with a high temperature of 77 degrees. This has
resulted in RH values near the 20 percent range for most of the CWA.
Much of the remained underneath the Extreme fire danger category
given the slightly weaker winds than yesterday, with the exception
of the Emporia area that recorded a peak gust of 34 mph.

For tonight, winds calm, becoming light and variable as a ridge axis
drifts southward into northern KS. Potent, incoming upper trough
across California will shift the upper low northeast and therefore
increase cloud cover towards southeast Kansas Saturday morning.
These clouds should dissipate as the low exits into Missouri during
the afternoon, bringing mostly sunny skies and light winds across
the CWA. Highs may be slightly cooler, given the weaker winds,
however still well above normal in the upper 60s. Increasing
moisture from the departing system lowers the fire danger threat
during the afternoon.

.LONG TERM...(Saturday night through Friday)
Issued at 322 PM CST Fri Feb 17 2017

The mid and long term period continues to look much warmer than
normal with focus on two storm systems Sunday night into Monday
and again Thursday into Friday. While there will be some
fluctuations in airmass temperature with the influx of the
trough-ridge-trough-ridge-trough pattern, the overall high and low
temperatures will remain quite warm at least through the middle of
next week. Normal highs are in the mid to upper 40s this week with
lows in the middle 20s but actual high temperatures will be in the
60s to 70s and lows mainly in the 40s or even low 50s.

The first storm system on Sunday night will see a pretty good
influx of moisture throughout the column but the two main elements
of forcing will split with one short wave trough lifting quickly
north into the main jet stream while the other more significant
chunk of energy will close off into the Gulf of Mexico. The local
forecast area will largely fall in between the two areas of best
forcing but with ample moisture and even some instability, expect
to see at least scattered showers and thunderstorms. Instability
is unlikely to be impressive given rather weak mid level lapse
rates but there are some indications that a few hundred J/kg of
MUCAPE will be expected so have included thunder potential
throughout the period.

The second storm system appears likely to be more impressive with
a strong jet streak forecast to move into the Plains with a
deepening upper low over the Central Plains. The current storm
track is a bit farther north than previous model runs with the
heart of the low tracking over Nebraska and a bit less
precipitation locally. I think the main takeaway point at this
time is that there is a good chance for a strong storm system to
develop at the end of next week, with both winter weather and
thunderstorms possible with this storm, but substantial
uncertainty in the storm track. Much cooler air is likely to
filter in behind this storm...with temperatures becoming near or
below normal.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1111 PM CST Fri Feb 17 2017

Have continued with a VFR forecast with model forecast soundings
backing off on stratus/fog development across east central KS. It
appears there is more mixing than earlier RAP solutions had
expected. As a consequence, LLWS has become a greater concern
with radar profiler data showing 30KT to 40KT at around 1500 feet.
This is expected to be short lived as the gradient relaxes while
the closed upper low weakens and the low level jet is expected to
diminish by about 10Z.


&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Prieto
LONG TERM...Barjenbruch
AVIATION...Wolters



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