Area Forecast Discussion
Issued by NWS Topeka, KS

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS63 KTOP 231119

519 AM CST Mon Feb 23 2015

...Update to aviation forecast discussion...

.SHORT TERM...(Today and Tonight)
Issued at 357 AM CST MON FEB 23 2015

Zonal mid-level flow was in place early this morning as the region
was wedged between a low over Nevada and a second mid-level low
north of the Great Lakes. At the surface, a 1046mb high will
continue to sink southward across the Central Plains this morning
before shifting to the southeast this afternoon into tonight. This
advancing high pressure resulted in light northeasterly winds and
steady cold air advection early this morning. Temperatures plunged
into the single digits near the Kansas/Nebraska border with readings
in the low teens over east central Kansas where mid-level cloud
cover limited the amount of radiational cooling. These temperatures
combined with northeasterly winds sustained at 8-10mph will keep
morning wind chill values in the negative single digits.

As the surface high shifts to the southeast today, winds will back
to the southwest this afternoon into this evening. However, this
wind shift likely won`t occur soon enough to have much of a warming
effect for today. The combination of persistent cold air advection this
morning and some mid-level clouds should limit high temperatures
today to the low/mid 20s. Winds will remain out of the southwest
overnight and actually increase into Tuesday morning as the pressure
gradient increases some over the area from a low pressure system
passing to the northeast of the forecast area. This southwesterly
flow will keep overnight temperatures warmer than this morning, with
lows in the middle teens.

.LONG TERM...(Tuesday through Sunday)
Issued at 357 AM CST MON FEB 23 2015

Tuesday looks to be a pleasant day with temperatures climbing well
into the 40s with westerly downslope winds and fairly deep mixing.
After the warmer day, overnight temperatures will fall to around 20,
and quickly rise on Wednesday morning (although incoming clouds from
the north will slow the rise in northern KS). These clouds are in
advance of a short wave trough moving down the Missouri Valley
from the north, and timing of the cloud cover could have a major
impact on the forecast for later in the day as a sharp temperature
gradient is expected across the area with the coolest temps in the
northeast and temperatures probably above 40 in the Abilene area.
The short wave will also bring a strong cold front through the
area by late Wednesday so temperatures will cool regardless, but
rain could be the dominant precip type in some areas during the
afternoon while snow would be favored in northeast KS.
Specifically regarding the potential for accumulating snow, the
path of the upper energy had been shifting east over recent model
runs and seems to have focused in on a common track that takes the
heaviest precip just east of the forecast area, clipping far
northeast KS. However, on the west edge of the upper trough, a
band of frontogenesis-driven precip may blossom across the
remainder of the area (should be noted that the ECMWF and GEM do
NOT develop this precip). The end result for the forecast is a
focus of the best chance for minor snow accumulations to be near
and east of a line from Marysville to Lawrence. However, there is
still some potential for almost the entire forecast area to see an
inch or more of snow IF the frontogenesis precip does indeed
develop as eagerly as recent NAM/GFS runs have predicted. The
timing of any snow would be entering far northern KS by mid
afternoon and spreading to east central KS by midnight...and
ending by 6 AM.

All model guidance is consistent in maintaining well-below-normal
temperatures for the remainder of the long term period. Thursday
and Friday in particular are likely to remain sub-freezing. During
that time frame, a long wave trough will be deepening in the
western CONUS, bringing southwest flow aloft to the Central
Plains. This flow pattern in conjunction with cold air at the
surface and occasionally ejecting short waves paint an interesting
forecast for the weekend. The initial wave to impact the local
area should do so on Saturday with accumulating snow possible if
it indeed tracks overhead as currently forecast. A negatively
tilted short wave will then quickly follow with more discrepancy
in the track. Despite the track discrepancy, there is a signal
pointing to additional accumulating winter precipitation...
potentially in the form of a mixed bag of rain/freezing
rain/sleet/snow across the forecast area. This is too far out and
with too much uncertainty to get into the details so the take away
point is that accumulating winter precip with multiple precip
types is possible over a prolonged period this weekend.


.AVIATION...(For the 12Z TAFs through 12Z Tuesday Morning)
Issued at 516 AM CST MON FEB 23 2015

For the 12z TAFs, VFR conditions are expected through the period.
Winds will back from northeast to southwest today as surface high
pressure tracks southeast of the TAF sites.




SHORT TERM...Hennecke
LONG TERM...Barjenbruch
AVIATION...Hennecke is the U.S. government's official web portal to all federal, state and local government web resources and services.