Area Forecast Discussion
Issued by NWS Omaha/Valley, NE

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FXUS63 KOAX 232108

Area Forecast Discussion
National Weather Service Omaha/Valley NE
408 PM CDT Thu May 23 2019

.SHORT TERM...(Tonight through Sunday)
Issued at 358 PM CDT Thu May 23 2019

Regional 88D mosaic was showing an area of elevated convection over
central NE approaching the western periphery of the CWA. Meanwhile
isolated cells were maturing across western KS on nose of
increasing low level moisture transport. Environment is becoming
increasingly moisture rich as GOES imagery was showing PW values
just south of the CWA were roughly 110-120% of normal.

Main issue to contend with continues to be threat of heavy
rainfall tonight leading to possible flash flooding over portions
of the southern CWA. Environment will be moisture rich through
tonight as moisture feed will be continuous with strengthening of
low level low level jet. RAP13 is showing PWs approaching 2
inches/KI over 40 by mid evening. Expect precip activity to
expand in areal coverage over the next couple hours over western
KS within 850-300mb diffluent regime/upper divergence via RRQ of
upper jet.

Synoptic scale ascent will will further be enhanced compliments of
strong differential divergence. In addition to strong environmental
instability...MUCAPE 1500-2000 J/kg...precip efficiency will phase
with nearly stagnant boundary layer moisture convergence thus
promoting cell regeneration through the night.

As mentioned, focus for heavy rainfall accumulations will be south
of I-80 with local amounts ranging from 1-2 inches quite possible by
early Friday morning. Additional rainfall will remain possible
mainly over the southern CWA from Friday afternoon through Sunday
thanks in part to a meandering surface boundary.

Given this, a Flash Flood Watch will be in effect this evening
through early Friday morning generally southeast of a line from
about Hepburn IA to Palmyra to Daykin.

Note: It is possible that total accumulations may reach 1.5-2 inches
by Sunday afternoon locally.

.LONG TERM...(Sunday night through Thursday)
Issued at 358 PM CDT Thu May 23 2019

Going forecast in the extended periods appears to be in good shape
so no major changes planned. Precip chances continue Memorial Day
through late Tuesday night with the approach of the next storm
system from the west. Otherwise dry Wednesday and Thursday.


.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1210 PM CDT Thu May 23 2019

Expect deteriorating conditions later today and into this evening
as thunderstorms increase in coverage. Some gusty winds possible
mainly at KLNK and KOMA this evening with chances dropping off
after about 2-3 am. Ceilings will trend down toward MVFR and
possibly into the IFR category.


NE...Flash Flood Watch from 10 PM CDT this evening through Friday
     morning for NEZ068-088>093.

IA...Flash Flood Watch from 10 PM CDT this evening through Friday
     morning for IAZ090-091.



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