Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 241705
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1205 PM CDT Tue Mar 24 2015

...Update to short term and aviation forecast discussion...

.UPDATE...
Issued at 1138 AM CDT TUE MAR 24 2015

Have made some relatively minor adjustments to the short term
forecast. The first was to lower temperatures, particularly in the
northeast as north central KS is still on track to have sunshine
late this afternoon and east central KS will have warm advection
with the warm front lifting into the area. The second was to
adjust precipitation chances. An area of enhanced lift was
currently bringing showers across north central and into eastern
KS so increased POPs within this band and track it steadily east
through early afternoon. Then adjusted precip chances to more
accurately time the motion of the strong upper trough currently
located in far northwest KS. The lift with the trough is currently
strong enough to produce shower activity moving across north
central KS at noon despite a strong elevated inversion. The main
question is whether the lift with this trough will be sufficient
to overcome the cap later this afternoon as it moves east.
Mid/upper level lapse rates are very steep near the trough axis
(12Z DDC RAOB had VERY impressive lapse rates which are advecting
into eastern KS). If the elevated cap weakens sufficiently, could
see elevated thunderstorms develop this afternoon even well north
of the sfc warm front, and these would again be capable of
producing some hail. Farther south, near the warm front, model
guidance is remarkably consistent in initiating deep convection
around 21Z near the surface low which should be in southeast KS.
It currently looks like convective towers should begin to go up
somewhere east of US75 and south of I-35, with actual storms
beginning to take shape as the forcing approaches the KS/MO
border. Supercell structures should rapidly develop at that point,
but the threat is likely to be out of the forecast area so at this
time will be closely monitoring the potential for any earlier
development (farther west), and also elevated storm potential
farther north and west this afternoon.

&&

.SHORT TERM...(Today and Tonight)
Issued at 351 AM CDT TUE MAR 24 2015

Early this morning, water vapor imagery showed moisture from the
advancing mid-level trough focused along the lee-side of the
Rockies.  At the surface, low pressure was centered over the
Oklahoma panhandle with an associated warm front stretching along
the Kansas/Oklahoma border. A weak passing vort max combined with
some isentropic lift helped to support shower and thunderstorm
activity early this morning along the Kansas/Nebraska border. A
southwesterly low-level jet will continue to advance eastward across
southeast Kansas this morning, resulting in warm-air advection
occurring over the warm front which was increasing the coverage of
the shower and thunderstorm activity across east central and
southeast Kansas. Short-range models show these storms skimming
across the far southeast corner of the CWA this morning, in which
some small hail will be possible with the stronger storms.

Models show the negatively-tilted mid-level trough advancing
eastward across the region today and exiting to the east by this
evening. A strong vort max will be present with this advancing
trough axis along with a decent amount of lift. However, model
soundings show the saturation depth decreasing this morning and
becoming more shallow, with a saturation depth up to around
750-800mb.  As a result, short-range models show some widely
scattered precipitation developing ahead of the approaching trough
with some periods of drizzle possible. The environment should
remained capped across much of the CWA through today with model
soundings showing some periods of elevated instability. As a result,
expect some scattered thunderstorms to develop throughout the day,
however these storms should remain below severe limits.  As the
trough axis moves through the area, expect these showers and
thunderstorms to exit from west to east through the afternoon hours
with dry conditions by this evening. Models show low clouds hovering
over the region through much of the day, gradually scattering out
during the afternoon and evening hours. With these overcast skies in
place, have dropped high temperatures for today by a couple of
degrees with readings ranging from the upper 40s northeast to the
low/mid 60s west and south. However, if the cloud cover is able to
scatter out sooner in the afternoon, then temperatures across north
central and portions of east central Kansas may be slightly higher.
With mostly clear skies expected overnight, cooled overnight low
temperatures a bit more with lows in the mid 30s north to low 40s
south.

.LONG TERM...(Wednesday through Monday)
Issued at 351 AM CDT TUE MAR 24 2015

Early Wednesday morning a surface low is forecast to be in far
southwest Kansas with a warm front extending east across northern
Oklahoma. Further north a cold front will be located across Nebraska
and northwest Iowa. An upper level trough will progress out of the
Rockies on Wednesday and move across the Plains. The cold front will
move southeast across the forecast area through the day. During the
morning some light showers will be possible across the western half
of the CWA as moisture surges north in return flow. By afternoon
the front will move to near I-35 by mid afternoon. Models suggest
convection may fire in the late afternoon when cooling aloft with
the advance of the upper trough and instability in place across
southeast Kansas. Models place the cold front by 00Z along the I-44
corridor then progress it southeast quickly through the night. The
upper trough axis moves through the CWA by 12Z Thursday. Ended the
precipitation chances after 06Z Thursday. However this will be short
lived as another wave on the back side of the broad upper trough
moves southeast across the Plains and brings a chance of showers in
the afternoon to the north central Kansas counties then a chance of
rain and snow across the rest of the area Thursday night. Models
show large scale forcing for ascent and mid to upper level
frontogenesis setting up to increase confidence and have increased
precipitation chances accordingly. Another wave will move southeast
quickly Friday evening and night and could squeeze out some showers
during the evening before the lift and Q-vector convergence and
850-500 mb frontogenetic forcing moves east into Missouri.
The rest of the forecast remains dry Saturday through Monday. A
shortwave trough moving across the northern Plains Saturday night
and Sunday will bring another cool front south across Kansas on
Sunday. Temperatures will start out in the 50s and 60s Wednesday
with 40s and 50s for highs Thursday and Friday before warming back
up in return flow Saturday and Sunday. Temperatures above normal are
expected on Monday. Lows will drop to near or below freezing
Thursday morning through Saturday morning before warming back into
the 40s for Sunday and Monday mornings.

&&

.AVIATION...(For the 18Z TAFs through 18Z Wednesday Afternoon)
Issued at 1138 AM CDT TUE MAR 24 2015

Expect MVFR cig/vis for the remainder of the afternoon through
around 00Z, give or take 1 hour. Cig heights will border on IFR,
with the best chance at FOE and will have to closely monitor
trends. Will have periods of light rain mainly before 21Z at MHK
and 22Z at TOP/FOE, with some potential for thunderstorms to
develop between 20-22Z. Finally, given nearly calm winds
overnight, clearing skies, and some recent rainfall, may have fog
development and have addressed the most likely hours.

&&

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

$$

UPDATE...Barjenbruch
SHORT TERM...Hennecke
LONG TERM...53
AVIATION...Barjenbruch





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