Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 050936
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
336 AM CST Wed Mar 5 2014
.SHORT TERM...(Today and Tonight)
Issued at 333 AM CST WED MAR 5 2014
Shortwave trough moving southeast across the 4 Corners and into New
Mexico at 08Z as seen on water vapor satellite loop. Profilers show
a weak disturbance moving through northwest Nebraska this morning.
Cloud cover has kept temperatures warmer than previously forecast
and have adjusted upward through sunrise. NAM has initialized too
cold as its 00Z model snow depth has 9 to 13 inches of snow over the
forecast area, so have thrown it out for use in temperature forecast
today and tonight. Latest regional radar at 09Z showing light
returns over south central and southeast Nebraska with only
sprinkles/flurries so far out of them.
Models take the New Mexico wave and and move it across the Southern
Plains. Better forcing will remain to the southwest of the CWA
today, but light mixed precipitation is still in the picture.
Initially snow and sleet is expected as model soundings and cross
sections show a warm nose. Cooling to the wet bulb will occur with
the precipitation changing over to all snow. Also the speed of the
system has slowed down and have slowly increased chances of
precipitation from northwest to southeast across the CWA today.
Temperatures will be warm enough out ahead of the precipitation
across east central Kansas and have increased high temperatures to
around 40 degrees, especially along and southeast of Interstate 35.
Also expected weather will be rain or snow along and southeast of
the Kansas Turnpike. Highs today should range from the upper 30s to
lower 40s along and southeast of the Kansas Turnpike with middle 30s
expected across the rest of the CWA. Any snowfall accumulations will
be around a half inch or less. By late afternoon temperature
profiles cool enough for all snow over most of the area except for
parts of east central Kansas where a rain or snow mix is possible.
The upper trough will move off to the southeast this evening and
overnight. Have kept small pops for the evening hours across east
central Kansas with precipitation gradually changing over to snow.
Clouds should begin to decrease tonight in the wake of the trough.
Lows tonight are expected to range from the upper teens to lower 20s.
.LONG TERM...(Thursday through Tuesday)
Issued at 333 AM CST WED MAR 5 2014
For Thursday, decent warm air advection is expected as the region is
wedged between surface high pressure to the south and east and
surface low pressure to the northwest, resulting in southerly flow
into the area. The NAM seems to have an overestimation of the amount
of snow on the ground as its temperature forecast has a notable
cold bias. Have trended warmer for Thursday temperatures with this
southerly flow, bringing highs into the mid/upper 40s to low 50s.
Thursday night through Friday night a mid-level trough will begin to
develop over the northern Rockies and Northern Plains, deepening a
bit into the Central Plains Friday into Saturday as this trough
progresses toward the Great Lakes region. This advancing trough will
help to push a cold front southward into the area Friday afternoon
into Friday evening, however there are still some minor
discrepancies with when exactly this boundary will move into
northern Kansas. At this time, models are in pretty good agreement
in having the boundary exiting southeast of the area Friday evening.
With this frontal passage, could see a spread in temperatures as
winds may start shifting from southwest to northeast during the
afternoon hours across the northern half of the forecast area, so
have a spread of upper 40s to middle 50s for high temperatures on
Friday. Models show some weak low and mid-level frontogenesis
present behind this boundary, which could support the development of
light precipitation late Friday afternoon through Saturday.
Precipitation type is a bit tricky as the mild temperatures on
Friday should steadily drop into the middle 20s to low 30s
overnight into Saturday morning. As a result, may see areas of light
rain develop initially before switching over to snow for many
locations. Since the mid-level trough is not very strong and does
not deepen further south across the area, do not anticipate much
cold air advection to occur behind this system with highs on
Saturday reaching into the upper 30s and possibly low 40s. With
these temperatures expected to rebound back above freezing on
Saturday, any lingering precipitation on Saturday could switch from
snow back over to rain. However, there is still a great deal of
uncertainty with regards to how quickly precipitation ends on
Saturday as model soundings show the potential for a decent amount
of dry air to move into the mid-levels by Saturday morning. At this
time, do not anticipate much in the way of accumulating snow --
probably around an inch or less.
Southwesterly surface winds return to the region by Sunday with high
temperatures rebounding to near or slightly above the seasonal
normals in the 50s. By Monday and Tuesday, a more zonal mid-level
flow sets up over the northern half of the conus. The warmest day of
the week looks to be Monday as decent warm air advection sets up
over the region with highs possibly reaching into the low/mid 60s. A
weak boundary should track across the area Monday night, but do not
anticipate much in the way of cold air advection behind it as highs
on Tuesday should only drop a few degrees into the 50s. Low
temperatures for the latter part of the weekend through mid-week
look to be a few degrees above normal in the 30s. The next chance
for precipitation looks to be mid-week as another shortwave
approaches the area.
.AVIATION...(For the 06Z TAFs through 06Z Wednesday Night)
Issued at 1140 PM CST TUE MAR 4 2014
Expect VFR conditions through the mid to late morning hours of
Wednesday. Stratus ceilings will lower to MVFR through the late
morning hours and may lower to near IFR ceilings Wednesday
Evening. There may be periods of very light sleet and snow
possible through the evening hours. The model QPF trends have been
decreasing, so it is uncertain if any light precip will develop.