Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
337 AM EDT Thu May 11 2023

Valid 12Z Thu May 11 2023 - 12Z Sat May 13 2023

...Heavy rain and instances of flash flooding are likely across far
northeastern Texas and the Lower Mississippi Valley today before the next
round of excessive rainfall enters south-central Texas on Friday...

...Severe thunderstorms and heavy rainfall expected for portions of the
Central and Northern Plains the next couple of days...

...Early taste of summer heat on the way for the West Coast by this
weekend...

The central United States will have no shortage of active weather through
early this weekend as chances for severe thunderstorms and flash flooding
span each day, while including a majority of the Great Plains. A Moderate
Risk (level 3/4) of Excessive Rainfall remains in effect for the Lower
Mississippi Valley and eastern Texas today, as thunderstorms move
relatively slowly within a moisture-rich environment. Intense rainfall
rates may quickly saturate soils and lead to rapid onset flooding over
northwest Louisiana and nearby far northeast Texas and southwest Arkansas.
Urban areas and flood-prone regions are especially at risk into this
afternoon. Storms are expected to pick up forward motion by this evening
and progress eastward through the Deep South, diminishing the flash flood
threat.

Meanwhile, a deep upper-level trough/closed low traversing the Southern
Rockies will aid in a strengthening storm system over the central High
Plains that will help fuel the chances for numerous showers and
thunderstorms across the northern and central Plains through the end of
the week. Plentiful atmospheric moisture content surging northward
throughout the Great Plains combined with upslope enhancement in the High
Plains will allow for heavy rainfall and scattered flash flood concerns
across much of the central/northern High Plains on Thursday. Saturated
terrain and additional heavy rain could lead to higher chances for flash
flooding across northwest Kansas and nearby sections of southwest Nebraska
and northeast Colorado. Additionally, thunderstorms may turn severe for
this region while also extending south into central Oklahoma. The Storm
Prediction Center has issued an Enhanced Risk (level 3/5) of severe
weather focused on western/central Kansas into central Oklahoma as a
favorable combination of instability as well as deep and low-level shear
has increased chances these storms may produce large hail, damaging winds,
and tornadoes, including the possibility of significant tornadoes. The
severe weather threat will shift into the Mid-Missouri Valley Friday and
Saturday as the system gradually moves to the east. The heavy rain/flash
flood threat will also likely linger further west for portions of the
Northern Plains under the influence of the upper low, with the potential
locally for multiple inches of additional rainfall on wet ground
conditions from Thursday.

The next round of excessive rainfall to impact the Lone Star State is set
to enter south-central portions of the region on Friday and linger into
the weekend. The main impacts through Saturday are anticipated to be
associated with the heavy rainfall and flash flooding threat. Although
this part of the country is designated as being within severe to
exceptional drought, the signal for areal average rainfall of 5"+ has been
persistent, which would expectedly prompt at least scattered if not
numerous flash flooding chances. As a result, a Moderate Risk of Excessive
Rainfall has been issued for parts of south-central Texas and the Hill
Country. Residents, visitors, and travelers across this region are advised
to plan ahead and heed any warnings issued should several flash flooding
events materialize. Additionally, severe weather will also remain possible
and embedded within the numerous developing thunderstorms across central
Texas. Damaging wind gusts, a few tornadoes, and potentially very large
hail could extend from south-central Oklahoma to the Edwards Plateau on
Friday.

Outside of the influence of the central U.S. system, a significant warming
trend is expected along the West Coast/adjacent Interior West heading into
the weekend. Temperatures will begin to rise 10-20 degrees above average
Friday, with highs reaching into the mid- to upper 80s as far north as
Oregon. By Saturday, highs could reach into the low 90s for areas just
inland from the coast, including Portland, Oregon. This will only be the
start of an early season heat wave focused on the Pacific Northwest
through early next week. Residents should remember proper heat safety tips
by staying hydrated and limiting extended time outdoors during the hottest
afternoon hours. Above average temperatures will also shift from the Great
Lakes to the Northeast/Mid-Atlantic Thursday-Friday. Most highs will be in
the upper 70s to low 80s across the region Thursday, with mid-80s forecast
for the Mid-Atlantic Friday. Elsewhere, highs will be near to above
average for the South, with 80s expected for most locations. The
Northern/Central Rockies and adjacent High Plains will be the one cool
spot as highs remain in the 50s and 60s under the influence of the
upper-trough/closed low and widespread precipitation.


Snell


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php