Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 230909
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
309 AM CST MON NOV 23 2015
.SHORT TERM...(Today and Tonight)
Issued at 307 AM CST MON NOV 23 2015
A northwest upper flow this morning is forecast to become zonal
across the Central and Southern Plains as an upper level trough
moves into the Pacific Northwest tonight. West to southwesterly
winds will become light south to southeast as low pressure develops
in the lee of the Rockies today. Southerly winds will increase
tonight as the low pressure deepens and pressure gradient increases.
Little in the way of clouds are expected through tonight and with
warm air advection will see temperatures almost 10 degrees above
normal for late November. Highs today should top out from the mid
50s in far northeast Kansas to the lower 60s near central Kansas.
Lows tonight in the mid and upper 30s are expected.
.LONG TERM...(Tuesday through Sunday)
Issued at 307 AM CST MON NOV 23 2015
On Tuesday a strong upper low tracks over the Pacific northwest and
along the west coast. Southwest flow aloft develops across the
plains in response to this upper low out west. Low level moisture
and cloud cover will gradually increase during this time frame. By
Tuesday night low level lift within this saturated layer should
support patchy and areas of drizzle, and if the lift is strong
enough there could be some light rain as well. The soundings show
that this saturation and lift continues into the day Wednesday.
Meanwhile an arctic high pressure moving southward through the high
plains sends a cold front towards the forecast area Wednesday
evening. It is this time the mid level moisture arrives and
shortwave energy begins to eject out of the Rockies, although the
main upper remains over the inner mountain west. This will cause the
front to gradually slide southeastward through the area. Rain should
increase in coverage during the overnight hours mainly along and
behind the front. By sunrise Thursday morning the front should
bisect the area from central to northeast KS. Models depict weak
shortwaves approaching from the southwest enhancing the precip
coverage and intensity along the front. The GFS and ECMWF both
depict very weak instability could accompany the front and therefore
support the slight chance for embedded thunder. Otherwise periods of
moderate to heavy rain are possible across east central and
southeast KS during the day Thursday.
Behind the front sub freezing air moves in from the northwest. A
majority of the models depict the freezing line entering north
central KS mid day Thursday. This freezing line will advance
southeastward during the afternoon into the overnight hours. Models
show light precip still possible within this sub freezing air. They
also have backed off on the warm nose temps greater than a few
degrees therefore have dropped the mention of freezing rain. So
think that snow and sleet will be the predominant precip type after
the change over. Accumulations are uncertain as of now and depends
on how much precip can be generated over this frontal surface, but
first glance appears to be light. By sunrise Friday the freezing
line attempts to reach portions of east central KS, before gradually
retreating back to the northwest through out the day. Precip should
come to an end by Friday morning so am not too concerned about this
period. The models then begin to differ on how to eject the main
upper low out of the Rockies sometime during the weekend. During
this time frame temps will be borderline for rain and or snow.
Although the GFS has now introduced a possible warm nose, which
could cause a wintry mix again.
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 505 PM CST SUN NOV 22 2015
Dry air and no forcing will lead to VFR conditions.