Area Forecast Discussion
Issued by NWS Topeka, KS

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FXUS63 KTOP 231743
AFDTOP

Area Forecast Discussion
National Weather Service Topeka KS
1143 AM CST Thu Feb 23 2017

...Update to aviation forecast discussion...

.SHORT TERM...(Today and tonight)
Issued at 325 AM CST Thu Feb 23 2017

Early this morning an area of low pressure was centered over far
southeast CO into southwest KS, with a nearly stationary boundary
extending eastward into south central to east central KS.  Further
west, a mid-level trough was noted over northwest Colorado, and this
eastward-advancing wave will impact weather conditions across the
CWA by early this evening.

Scattered mid/high clouds were streaming across the region early
this morning north of the stationary boundary.  This cloud cover
helped to provide some insolation, keeping low temperatures in the
40s.  While models show this boundary lifting a bit further north as
a warm front today, models have limited the northward progression of
this warm front across the CWA.  As a result, this boundary may only
lift to around the I-35 corridor before getting shunted eastward by
the advancing mid-level wave. This boundary placement will certainly
have an impact on temperatures today, and expect a modest
temperature gradient to develop near the front. With this frontal
movement in mind, expect winds to become southerly across far east
central KS, resulting in high temperatures reaching into the low/mid
70s.  North of the boundary (i.e., north of around I-35) the winds
will remain out of the east/northeast, which will limit high
temperatures to the mid 50s to mid 60s from north to south.

Short-range models continue to show some scattered precipitation
developing this morning along and north of this boundary, however
model soundings still show a decent amount of dry air in the low
levels.  So the question becomes whether or not the mid-level
moisture will be able to survive through the dry layer.  As a
result, have only slight to low-end chance PoPs for light showers
this morning into this afternoon.  Focus then shifts to the
advancing mid-level trough which will track a few embedded
shortwaves across NE and far northern KS.  While the better moisture
and forcing will be focused closer to the shortwave across NE,
models show scattered precipitation extending southward into far
northern KS possibly as early as late this afternoon and continuing
through the evening and overnight hours. Model soundings show a
strong cap in place through most of the day, with this cap not
eroding away until early this evening.  With some steeper mid-level
lapse rates expected, some weak elevated instability may be present
to result in some isolated to scattered thunderstorms across far
northern KS. This instability combined with strong 0-6km shear
values may result in a marginal risk for some isolated hail
development near the KS/NE border this evening. As the surface low
shifts east of the area overnight and breezy northwesterly winds set
up over the CWA, overnight low temperatures should plunge into the
low 30s to low 40s from north central to east central KS.  With near-
freezing temperatures across north central KS by Friday morning, any
light precipitation present from the passing shortwave would likely
transition to light snow.

.LONG TERM...(Friday through Wednesday)
Issued at 325 AM CST Thu Feb 23 2017

Wrap around precipitation will continue on Friday as the upper low
over eastern Nebraska moves eastward through the day. Tight pressure
gradient through the day will bring gusty northwest winds to the
area. Have increased winds a few knots above model blends.
Precipitation looks to be a mix of rain and snow across the area on
Friday morning with a few small areas of some freezing rain possible
for a couple of hours. Snowfall amounts will be generally less than
an inch across the northern counties through the day. Light
precipitation will come to an end during the evening hours as the
system moves off to the east. Temperatures on Friday will be much
cooler than the last few days with readings in the 30s and 40s for
highs. Saturday will be dry with highs in the 40s which is normal
for late February. The next chance of light precipitation occurs on
Sunday into early Monday as the next in a series of waves moves
through the nearly Zonal flow. Models differ with the this system in
timing and location. The GFS is more progressive and further north
than the ECMWF therefore have kept precipitation chances on the low
side. Thermal profiles suggest that precipitation will begin Sunday
morning as light snow then transition over to rain by late morning
and through much of the evening, with a mix of rain and snow prior
to midnight. The next system quickly follows on Tuesday as an upper
level trough moves out into the Plains. The precipitation looks to
mainly fall as rain with a mix of rain and snow Tuesday evening in
north central Kansas before it ends. Wednesday looking dry with cool
high pressure building into eastern Kansas. Temperatures warm back
up to above normal readings by Monday with 60s expected Tuesday
before cooling back into the 50s on Wednesday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1138 AM CST Thu Feb 23 2017

VFR conditions are expected through the afternoon into the
evening. Scattered showers and thunderstorms are expected to
develop across portions of central KS this evening. Introduce VCTS
at MHK between 00Z and 04Z. Current expectation is for
thunderstorms to remain north of the Topeka terminals. I also
expect MVFR cigs to overspread all terminals between 02Z and 05Z.
Easterly winds will remain gusty near 20-25 knots through the
afternoon. Winds will begin to back to the north and northwest
overnight, remaining strong with sustained near 15 knots and gusts
approaching 25 knots.


&&

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

$$

SHORT TERM...Hennecke
LONG TERM...53
AVIATION...Baerg



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