Area Forecast Discussion
Issued by NWS Topeka, KS

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000
FXUS63 KTOP 282025
AFDTOP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
325 PM CDT Thu May 28 2015

.SHORT TERM...(This Evening through Friday)
Issued at 255 PM CDT THU MAY 28 2015

On Thursday afternoon, an unorganized and rather chaotic atmospheric
setup was in place over Kansas. Several mesoscale features were
evident in radar imagery as rotating areas of precip represented
small scale energy. One larger vorticity maxima was moving northeast
across western Iowa while another was moving northeast across
southwest Missouri. Smaller scale vorticity maxima appeared to be
moving east across north central Kansas with another moving nearly
due north across extreme eastern Kansas. All of these vort maxima
were producing enhanced areas of showers and some thunderstorms as
the weak enhancement in vertical motion was easily enough to
overtake a weakly capped and weakly unstable environment. However,
in the past hour have seen a general decrease in precip coverage
likely a result of the larger scale circulations shifting off to the
east. In the short term, through mid evening, expect scattered
showers and a few storms to continue although also expecting a
continued decrease in coverage. Severe weather potential is minimal
although any convection able to develop from Salina toward Emporia
could be strong as there is a bit of clearing and warming taking
place in that region. Flooding potential also seems minimal through
this evening given decreasing trends, but if a convective cluster
was able to develop and train over some of the areas that have
received heavy rain in the past 24 hours there is some small
potential for localized flash flooding.

For tonight`s forecast into Friday morning, we must take a broader
look at forcing mechanisms as the mesoscale features have proven
extremely tough to predict with accuracy. A trough axis evident in
water vapor imagery extended from Wyoming through central Colorado
and into eastern New Mexico with several individual smaller vort
maxima evident within the trough axis. Upslope flow in conjunction
with the approaching upper energy has already initiated widespread
thunderstorms across the High Plains region, and model guidance is
rather consistent in tracking the vorticity into central KS by early
Friday morning and into eastern KS by sunrise on Friday. Thus, have
at least mid range confidence in a convective cluster developing
across western KS this evening and tracking east across the state
overnight into Friday morning, not unlike what developed and move
east last night into Thursday AM. However, it is not clear cut how
far east this complex will progress before dissipating as the low
level jet veers with little LLJ convergence. There are indications
of some elevated instability which may sustain the complex as it
moves east IF there is enough forcing in the low levels. Will be
something to monitor this evening but for now have gone with fairly
high PoPs for the entire area through Friday morning.

Friday looks to be messy on the mesoscale once again with the main
upper trough approaching from the northwest and smaller features
likely impacting the area as well. There is a strong signal for
periods of rain and thunderstorms especially south of a Marysville
to Abilene line through the day so have kept higher PoPs in those
areas. Flooding will be dependent upon the persistence of rain over
an area, and given the expected scattered nature of storms through
the day, have not issued any flood watch products at this time.
Expect plenty of cloud cover through the short term period which
will keep lows warm  in the 60s tonight and high temperatures in the
mid 70s again on Friday.


.LONG TERM...(Friday Night through Thursday)
Issued at 255 PM CDT THU MAY 28 2015

Main positive tilt longwave trough will move across the region
forcing a cold front southward through the state on Friday night.
Showers and thunderstorms along the front should exit the area
around 12z Saturday or shortly thereafter. The 700mb trough passes
by midday so there could be lingering cloud cover but cooler and
drier air will move into the area setting up a much needed dry
period for most of the weekend and into next week. In fact, both
ECMWF and GFS suggest dry weather could persist into next Weds
before the next upper trough moves into the Plains with the next
chc for storms expected to be sometime later Weds into Thurs.
Temps should rise back toward avgs in the upper 70s to lower 80s
while dewpoints should stay in the 50s through Monday before
southerly flow develops Tues with dewpoints expected to be back in
the 60s by then.

&&

.AVIATION...(For the 18Z TAFs through 18Z Friday Afternoon)
Issued at 1229 PM CDT THU MAY 28 2015

Rain is currently moving NE toward TOP/FOE.  Expect to see some on
and off again -RA at these terminals for the next couple hours
before this system moves east of the area.  Storms are firing up
near MHK, so have mentioned VCTS until 21Z before clearing.  A
period of VFR is expected from this afternoon until early morning
tomorrow before another system moves through from the west.
Confidence in the timing and exact evolution of this system are low
right now.  Have VCTS starting at MHK at 10Z, with TOP/FOE seeing
VCTS at 12Z.


&&

.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...Barjenbruch
LONG TERM...Omitt
AVIATION...Heller





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