Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 230837
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
337 AM CDT Thu Oct 23 2014
.SHORT TERM...(Today and Tonight)
Issued at 329 AM CDT THU OCT 23 2014
Shortwave trough currently moving across the central and northern
plains this morning. Mid level forcing and some weak frontogenesis
has caused a band of showers to form and progress eastward through
the forecast area. Instability is limited due to mid level capping
and weak lapse rates, so only expect isolated thunder at times.
Rainfall amounts appear to generally be at or under a quarter of an
inch. The back edge of the precipitation has already passed through
north central KS and expect that clearing out from west to east to
continue through the morning. Models agree that the last of the rain
should exit east central KS around 16Z. The uncertainty with this
forecast is how long the clouds linger behind the band of showers.
Also, patchy fog will be possible across north central KS later this
morning. Although current IR shows low stratus already building into
that area, which may limit fog development. If the clouds hold into
the early afternoon hours or later the temperatures today will be
cooler. Some of the short term models are suggesting that the clouds
could hold through the overnight hours across most of the area. Have
lowered the high temps a few degrees into the mid to low 70s to
account for this scenario. Also kept the trend of the coolest
locations being east and north central KS where the clouds will
likely linger the longest. The NAM is suggesting clouds will last
through tonight only to clear out early tomorrow morning, which
could set up the potential for fog again. Confidence in the forecast
beyond mid day is low at this point.
.LONG TERM...(Friday through Wednesday)
Issued at 329 AM CDT THU OCT 23 2014
Friday through Saturday...a southern stream upper level ridge will
move eastward into the southern and central plains.
On Friday, Westerly 850mb winds will advect 19-22 DEG C 850mb temps
across the CWA Friday afternoon. Deeper mixing will allow surface
winds to become southwesterly and temperatures to warm into the
lower to mid 80s.
An upper level trough will ride over the southern plains ridge axis
and deepen as it digs southeast across the Great Lakes States. Weak
CAA across the upper Midwest into the mid MS river valley Friday
night into Saturday morning will cause a weak back door cold front
to push southwest across the CWA on Saturday. Highs will be slightly
cooler in the mid 70s to around 80 degrees.
Sunday through Monday, an upper level trough across the western US
will move east across the central Rockies into the high plains by
00Z TUE. A lee surface trough will deepen across western KS during
the day on Sunday. Stronger southerly winds will help to warm
temperatures into the lower to mid 80s Sunday afternoon. A surface cold
front will begin to push southeast into north central KS Monday
afternoon and there may be enough surface convergence ahead of
the front for isolated showers and thunderstorms to develop late
Monday afternoon. Southerly winds will allow temperatures to warm
into the mid to upper 70s despite increasing cloud cover.
Monday night through Tuesday evening, the upper level trough will
move east across the plains and amplify. Stronger ascent will allow
Showers and thunderstorms to develop across eastern KS ahead of the
front as well as post frontal. The front will move southeast of the
CWA by 12Z TUE thus most of the thunderstorms should move east into
MO. The post frontal rain showers will last through most of the day
but should move out of east central KS during the early evening
hours of Tuesday as the upper level trough axis moves east into MO.
Highs on Tuesday will only reach the mid 60s with cloud cover, periods
of light rain and northwest winds of 15 to 20 MPH.
Wednesday, skies should clear during the morning hours. A surface
ridge of high pressure will move southeast across the CWA into OK
and AR by the late afternoon hours. Highs will continue to be in the
lower to mid 60s despite insolation during much of the day.
.AVIATION...(For the 06Z TAFs through 06Z Thursday Night)
Issued at 1139 PM CDT WED OCT 22 2014
Confidence in MVFR CIGS continues to be low as the MVFR CIGS progged
earlier have yet to develop. CIGS within the SHRA have remained
VFR and the only indications of restricted VSBY or CIGS is along
and behind the surface trough axis where there is some cooling
occurring. With guidance continuing to advertise MVFR CIGS through
the morning, will keep the forecast pretty much unchanged. Have
however backed off on CIGS below 2 KFT. With the lower res models
keeping the surface trough axis to the northwest of MHK, am
thinking that the forecast may be on the pessimistic side. However
if skies clear out and temps drop as the higher res solutions
would have, CIGS and VSBY could crash. This would be more likely
for MHK While TOP and FOE remain within the warm sector and
overcast mid level clouds preventing radiational cooling.