Area Forecast Discussion
Issued by NWS Springfield, MO

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FXUS63 KSGF 201121

Area Forecast Discussion
National Weather Service Springfield MO
621 AM CDT Thu Apr 20 2017

...12z Aviation Update...

.SHORT TERM...(Today and tonight)
Issued at 333 AM CDT Thu Apr 20 2017

A cold front extends from eastern IA to southeast KS. Scattered
showers/tstms are occuring over western MO/eastern KS and we`ve
seen some winds gusts of 30-35 mph with strongest convection in
eastern KS, but trends have been weakening since then. In the
near term that activity will move east into the Truman Lake region
toward 12z/7am. HRRR does indicate some convection farther south-
southwest along the front in the near term. Will update as trends

GFS progged soundings show diurnal destabilization with mlcapes
close to 1000-1200 j/kg during the afternoon southeast of a Osage
Beach to Joplin line. Some redevelopment along the front is
possible with a marginal/limited wind/hail threat. The sfc
front shifts south/east of our eastern cwfa by 21-22z/4-5 pm.
High res radar sims don`t show much precip coverage in our area
this afternoon with 3km NAM showing somewhat more robust (small)

The front will moves off to our south tonight extending from the
OH Vly into AR and se OK. A jet streak and shortwave digging ese
through the southern Rockies along with a lead impulse over the
Plains will allow convection to redevelop over southern Plains
into our western counties overnight. This will be the beginning
of rounds of heavy showers into Fri-Fri night.

After coordination with other offices, will make no changes to the
watch attm. The ongoing watch handles the expected initial precip

.LONG TERM...(Friday through Wednesday)
Issued at 353 AM CDT Thu Apr 20 2017

The basic scenario hasn`t changed as the upper level wave to our
west closes off and approaches us Fri-Fri night when the heaviest
rain will likely occur.

Fri-Fri night-Sat: The upper low closes off over western KS early
then moves east reaching close to the MO/KS border by 09z/4am
overnight. Strong lift will occur in the exit region of jet
rounding the base of the upper low with periods of heavy rain Fri-
Fri night, then tapering off/diminishing late Fri night into Sat
as the best lift shifts east.

The 00z GFS was lower on storm total rainfall versus most other
guidance. Tried to use a blend of the ECMWF and WPC guidance where
I could. There will be a fairly strong cutoff to the northern
extent of potentially excessive rainfall. Our fcst grids are not
much of a departure from the previous forecast, generally ranging
from two inches over central MO to just over four inches over the
far southwest corner of Missouri. Rainfall like this over a large
area will cause areal flooding of creeks/rivers/low water
crossings and other poor drainage areas.

It will be down right chilly with some areas staying in the upper
40s all day Saturday with gusty east winds shifting to the north
as the low exits.

Sunday-Wed: Sfc high pressure moves through Sunday-early Mon.
Gusty south winds develop Mon ahead of an upstream sfc front and
shortwave over the northern and central Plains. Another chance of
showers could develop with another front by Wed, but by that time
there is wide variance on the timing and evolution of that next


.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 621 AM CDT Thu Apr 20 2017

The first wave of showers and a few embedded thunderstorms is
currently moving over the JLN terminal. This activity will
continues to slide eastward and should affect the SGF terminal
within the hour. Covered morning activity with VCs and TEMPOs
respectively. With any heavier shower/tstorm activity we may see
brief drops from MVFR to IFR conditions.

A break in the activity will occur later this morning and into the
afternoon. Can`t rule out a rogue shower or Tstorm so VCs to cover
this time. VFR or perhaps MVFR overcast conditions expected
through much of the afternoon and evening. More showers and storm
activity expected later this evening and overnight. Again, heavier
rainfall/storms will bring down ceilings and visibilities into
the IFR range at times.


MO...Flood Watch from late tonight through Saturday morning for

KS...Flood Watch from late tonight through Saturday morning for



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