Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO
FXUS63 KEAX 211119
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
619 AM CDT Mon Apr 21 2014
Issued at 343 AM CDT MON APR 21 2014
Showers with a few embedded thunderstorms have blossomed over the
region in the last few hours. Anticipate precipitation continuing to
expand in coverage as the shortwave trough approaches from the west
and the surface boundary advances southward. The southward push may
be enhanced by thunderstorm outflow from more numerous and stronger
convection over Nebraska. Instability continues to look weak and
shear is very weak so the threat of severe weather is very low.
Rather it looks like scattered to widespread moderate rain showers
with lower coverage of storms will occur. Temperatures continue to be
a challenge today. Numerical guidance seems too warm given what
should be thick cloud cover and potentially numerous areas of
precipitation. Southeastern portions of the forecast area may not
break out of the clouds today with precipitation ending in the late
afternoon. Really think these areas will not have much of a warm up,
or not nearly as warm as some guidance suggest. The going forecast
looked pretty good and 00Z 21 NAM also indicated this notion. So the
high forecast utilizes a mix of these two.
Tuesday - Wednesday:
Quiet weather is expected Tuesday with seasonal temperatures. High
pressure will build into the region behind the departing storm
system. The airmass moving in is only modestly cooler than the
airmass its replacing so highs in the mid 60s to lower 70s continue
to look likely.
Strong warm/moist advection and lift is expected through the day
Wednesday and there will be at least a chance for showers and storms
to develop across northern Missouri during the day Wednesday. Highs
look to climb into the upper 70s to perhaps the 80s in our
southwest. Also with moisture flowing northward, it should start to
feel more humid as dewpoints climb into the mid 50s by the
Wednesday Night - Thursday:
Models have come into much better agreement with the timing of the
surface front. We should see the front into northwestern Missouri by
daybreak Thursday with a line of convection associated with it. This
will be enhanced by a strong trough moving the Central/Northern
Plains that may begin to take a more negative tilt Wednesday night.
With the front possibly moving through earlier in the day, the
instability looks a little weaker despite strong shear and dynamics.
Given the strong shear and dynamic system, the threat of severe
weather still can`t be ruled out so will continue mention of a low
threat of severe weather in the HWO.
Friday - Sunday:
Beyond Thursday, model guidance begins to vary and this becomes
quite noticeable by Friday. The GFS surges the Thursday front much
further south and reinforces it with a dose of cooler air out of the
Canadian prairies. The ECMWF and the GEM don`t advance that front as
far south and as a result keep temperatures about 15 degrees warmer.
By Saturday, the ECMWF has the area within a robust warm sector
while the GEM trended more with the GFS in moving cooler air further
south. There is almost a 30 degree temperature spread by Saturday
afternoon. But it gets better. By Sunday, each model is similar to
their previous day forecast but now the spread has increased to
around 40 degrees. GEFS ensemble mean and standard deviation plots
also show a great deal of variability with high amount of standard
deviation. Given the extreme variability noted in the models there
is very little confidence in the extended portion of this forecast.
.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 619 AM CDT MON APR 21 2014
Conditions should mostly be VFR through the period but a window of
MVFR is possible if/when any kind of precipitation moves into a
terminal. The best chances for precipitation at the terminals looks
to be this afternoon as the front pushes through the area. But there
could potentially be a shower or storm at any time through the day so
have just carried a VCSH mention until the front moves into the area.
Southwest winds will veer progressively to the west and eventually
the north after the front pushes through. Some slightly stronger
winds are possible immediately behind the front. Skies are expected
to clear behind the front with high confidence in VFR conditions this
evening through the overnight.