Area Forecast Discussion
Issued by NWS Topeka, KS
FXUS63 KTOP 271126
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TOPEKA KS
626 AM CDT Sun Jul 27 2014
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 257 AM CDT SUN JUL 27 2014
During the early morning hours, a few thunderstorms have been able
to develop amidst a band of moderate to strong instability
stretching across east central Kansas. These storms appear elevated
in nature, at least initially, but model soundings suggest that once
updrafts develop they could become somewhat surface based. Radar
signatures have at times suggested localized gusty winds within
downdrafts, but winds stronger than 40 mph appear quite unlikely.
The storms have also struggled to become strong enough to produce
hail larger than peas, probably due to the most unstable
near-surface parcels still being capped. This activity should drift
toward the southeast with some potential for additional development
toward the Ottawa and Garnett areas with time. Expect the
LLJ-enhanced convergence that seems to be responsible for developing
these storms to weaken by sunrise as the LLJ continues to veer and
the frontal zone shifts south, and convection should dissipate or
move south of the area by sunrise as well. The remainder of the
today/tonight period is likely to be dry across the area.
Temperatures will be cooler today, but still in the upper 80s to
lower 90s. The much cooler air will arrive overnight as another
punch of cold advection brings 850 temperatures into the lower to
middle teens (Celsius). Skies should be mostly clear overnight but
expect a bit of a breeze to continue so lows should hold in the 58
to 63 range. If winds become calm though, those numbers could fall a
.LONG TERM...(Monday through Saturday)
Issued at 257 AM CDT SUN JUL 27 2014
Northwest flow aloft continues for much of the coming week. No
discernable system appears for Monday and Monday night and dry
forecast in order for those periods.
While medium range models agree on overall pattern, and do not
have appreciable shortwave troughs affecting eastern KS, there are
considerable model differences in predicted QPF throughout the
forecast period. First discrepancy shows up for Tuesday as GEM and
ECMWF develop convection in Nebraska and move it southeast into
northeast KS during the morning, while NAM, last two runs of GFS
are GFSEnsemble are dry. Will tend toward the dry side for Tuesday.
All models develop a northwest to southeast oriented band of
precipitation Tuesday night over eastern KS associated with 600 mb
frontogenesis and elevated instability. Best chances appear to be
over southwestern half of forecast area with lesser chance in the
far east. Precipitation chances continue into Wednesday, with the
best chances once again over the southwest half.
Upper flow pattern from Wednesday night through Saturday turns
from northwest to more northerly. 00Z ECMWF is relatively dry
through that period with upper low positioned farther east, while
its previous run, and 00Z GFS have periodic low amplitude shortwaves
dropping south/southeast through the eastern Plains resulting in
several rounds of precipitation. While confidence is not high,
have low chance POPs for most periods during the latter half of
Temperatures are forecast to be cooler than normal for this time
of year with highs mainly in the lower to middle 80s and lows in
.AVIATION...(For the 12Z TAFs through 12Z Monday Morning)
Issued at 614 AM CDT SUN JUL 27 2014
VFR conditions are likely through the TAF period, but with some
small potential for reduced visibility between 10Z and 12Z Monday.
North winds may gust up to 25 kts this afternoon.