Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 161746
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
1246 PM CDT Sun Mar 16 2014
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 307 AM CDT SUN MAR 16 2014
08Z water vapor imagery shows a shortwave lifting east northeast
through the ARKLATEX region with some energy left behind over ELP.
Also a shortwave trough was noted swinging through eastern NEB.
Surface obs indicate a low pressure center near the ARKLATEX as well
with 3 hr pressure rises across northeast KS around 4 MB. Profiler
data suggests the 850 MB front has moved through most of not all of
the forecast area.
Now that the 850 front has moved through, models indicate dry air
will continue to advect south through the morning. And once the
shortwave trough axis over NEB passes to the east, there should not
be much in the way of forcing for precip. Regional radar has some
light returns across southeast NEB, but this is likely just trace
amounts or flurries with the NEB WFOs getting reports of a dusting
or light accumulations on cars. Therefore the forecast has things
winding down through the morning. The 00Z NAM has backed off on the
strength of the pressure gradient from earlier runs and while
sustained speeds have only flirted with 30 MPH, there have still
been an occasional gust over 40 MPH. Because of this will likely
keep the southern half of the wind advisory going this morning.
However if the pressure gradient weakens enough, we may be able to
cancel it before noon. Models show the boundary layer mixing to
around 850 MB this afternoon. Since there isn`t a great deal of cold
air with the front and the prospects for some good insolation across
north central KS this afternoon, have highs forecast to warm into
the lower and middle 40s. Cloud cover hanging on longer into the
afternoon across far eastern KS is expected to keep afternoon highs
in the upper 30s or around 40. Lows tonight will again be tricky
with skies clearing out and a weak ridge axis passing over the area.
Winds switch around to the south and gradually increase overnight
across north central KS. Think this may aid mixing of the boundary
layer and keep lows in the upper 20s. Elsewhere along the KS river
valley and over east central KS, the ridge axis is expected to keep
winds light for a longer period of the night allowing radiational
cooling to drop lows into the lower 20s especially in the areas
prone to seeing large drops in temps once the wind goes calm.
.LONG TERM...(Monday through Saturday)
Issued at 307 AM CDT SUN MAR 16 2014
Overall drier weather pattern in the extended forecast as a series
of disturbances originating from the Pacific keep higher
precipitation chances further north. Gusty winds continue
throughout the week.
Monday is on track to be a more pleasantly warm day as high pressure
shifts off to the east as southwest winds respond to a developing
surface trough over the western high plains. Wind gusts range
between 20 and 30 mph during the afternoon as dewpoint temperatures
mix into the 20s to low 30s. Decent southwest flow at h85 across
north central KS should pull temps warmer above previous guidance
near 70. Further east, the slightly weaker warm advection limit
readings to the 60s. These conditions will set the area up for very
high fire danger conditions again in the afternoon as minimum
humidity values fall in the low and middle 20s.
Surface trough becomes a closed low as it phases with the
approaching upper wave by Monday evening. Expect southerly winds to
remain gusty Monday evening into Tuesday as the wave passes to our
north, forcing another cold front through Tuesday. 15 to 25 mph
sustained winds from the southwest overnight switch to the west and
northwest behind the front entering north central KS late Tuesday
afternoon. Speeds increase between 20 and 30 mph sustained through
at least midnight Wednesday before gradient wanes. Models are
continuing to trend warmer Tuesday with the increasing warm
advection ahead of the front, however some uncertainty on the
strength of the thermal ridge ahead of the boundary which could
raise current forecast highs in the lower to middle 60s. Slight
chances for rain were mentioned on Tuesday and Tuesday evening for
locations near the Kansas and Nebraska border. The latest ECMWF,
GEM, and SREF indicate upper forcing combined with some saturation
could stretch into our area, however confidence in this occurrence
is low based on high cloud bases and lack of good saturation on
Precipitation chances become less certain Wednesday through Saturday
as zonal flow brings a series embedded disturbances, varied in
timing from each model run. The ECMWF tries to bring another weak
wave behind the exiting trough Wednesday evening while the GFS
depicts ridging and subsidence behind the trough. Will leave dry for
now as this is the first run of the ECMWF depicting this solution.
Somewhat better congruency on Thursday evening into Friday as another
shortwave trough enters the central plains. Have continued to side
with the ECMWF placing the better forcing further north. Soundings
from the GFS depict little moisture available, however with a cold
frontal passage expected Friday, will continue to monitor trends as
there could be some forcing for precip along the boundary. A
stronger upper trough begins to organize off the CA coast by
Saturday with major discrepancies on timing of minor waves ejecting
ahead into northeast Kansas. Have continued a dry forecast for now,
but would not be surprised if better precip chances return at the
end of the week. Passing cold front on Tuesday and Friday will only
cool highs slightly will overall readings through the week in the
50s and 60s. Overnight lows range in the 30s to low 40s.
.AVIATION...(For the 18Z TAFs through 18Z Monday Afternoon)
Issued at 1246 PM CDT SUN MAR 16 2014
For the 18z TAFs, VFR conditions are expected through the period.
The breezy northerly winds will continue to diminish during the
afternoon hours as the pressure gradient weakens over the area. As
surface high pressure tracks over the region tonight into early
Monday morning, winds will become light and variable before shifting
to the southwest by Monday morning. These winds are expected to
increase once again Monday afternoon.