Area Forecast Discussion
Issued by NWS St. Louis, MO

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873
FXUS63 KLSX 252250
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
550 PM CDT Fri May 25 2018

.SHORT TERM...  (Through Late Saturday Afternoon)
Issued at 326 PM CDT Fri May 25 2018

A fairly complex and messy pattern will result in scattered
thunderstorm activity this evening. Expect storms to decrease after
sunset with much of Saturday remaining dry. There is some question
as to whether another complex of storms develops over Iowa,
approaching from the north Saturday night.

Vis sat showed the first of the MCV features near Quincy, which will
continue to quickly race off to the northeast this evening.
Scattered thunderstorms with pockets of locally heavy rain will
follow suit, entering into central Illinois by mid-afternoon.

The second such wave is evident in the tight rotation over southeast
Kansas. Thunderstorms currently over southeast Missouri are running
well ahead this MCV. These storms originated along the outflow from
early morning convection and are converging along the western
periphery of the southeastern ridge. Given decent afternoon
instability, especially in areas rain has not fallen, expect
thunderstorms chances through sunset. Additional showers/storms
could fire around the wave as it travels through southern Missouri
tonight. Much of this will stay well south of St. Louis, possible
skimming the southern portion of the CWA. Storms are not expected to
be severe.

Saturday should mainly be dry and very warm with a decent amount of
sunshine. The biggest question pertains to yet another MCV that
could develop over Iowa. As ridging builds in from the west, high
res guidance over the last couple of days has hinted at development
late Saturday over the tri-states region (IA/MO/IL), pressing
southward down the east side of the ridge Saturday night. Provided
the uncertainty, maintained chance precip through Saturday
afternoon.


Maples

.LONG TERM...  (Saturday Night through Next Friday)
Issued at 326 PM CDT Fri May 25 2018

Saturday night through Monday...

  An upper level trough will continue to lift out of the area on
Saturday night with isolated showers and thunderstorms possible over
northeast Missouri and western Illinois. A ridge aloft and at the
surface will take hold of the weather pattern on Sunday with 850
temperatures over the area in the range of 17 to 20 C leading to
highs in the  low to mid 90s. There will likely be a small cap aloft
to inhibit diurnal convection in the afternoon over the area on
Sunday. Monday will continue the hot trend with 850 temps again
within the 18-20 C range over the area leading to highs in the low
to mid 90s again over the area. Temperatures on both Sunday and
Monday will be in record territory with a few records falling not
out of the question.


Monday night through Friday...

Subtropical storm Alberto will make landfall somewhere along the
Gulf coast sometime early next week. The latest model guidance is
still showing some differences on where the remnant low will travel
after making landfall somewhere along the Gulf coast. The GFS brings
the subtropical storm Alberto onshore early next week with the
remnant low moving around the periphery of the ridge off the
southeast US coast from Tuesday through Friday. The ECMWF also
brings subtropical storm Alberto onshore early next week, but brings
it up the lower Mississippi Valley on Tuesday then into the
Tennessee and Ohio Valley on Wednesday into Thursday. If the ECMWF
is correct, then the forecast area will see some cloudiness over
parts of southeast Missouri and southwestern Illinois on Wednesday
into Thursday. That being said, an upper level ridge over our area
is expected to weaken overheard starting Monday night. This will
allow for the area to be more susceptible to diurnal convection from
Tuesday through early Friday. A ridge over the southwestern US will
build back into the area by Friday afternoon. Temperatures will
remain between 10 to 15 degrees above normal through the end of May
into early June.


Kelly

&&

.AVIATION...  (For the 00z TAFs through 00z Saturday Evening)
Issued at 522 PM CDT Fri May 25 2018

Although it appears that most of the showers/storms this evening
will occur east and south of the taf sites ahead of upper level
disturbances in a moist and unstable atmosphere, there may be a
few storms early this evening in the St Louis metro area. These
showers/storms along with diurnal cumulus clouds should dissipate
later this evening due to the loss of daytime heating. Mainly just
some high level cloudiness remaining for the late night and
morning hours. Prevailing weak south-southwest surface winds can
be expected through the forecast period.

SPECIFICS FOR KSTL: Although it appears that most of the
showers/storms this evening will occur east and south of STL
ahead of upper level disturbances in a moist and unstable
atmosphere, there may be a few storms early this evening in/near
STL. These showers/storms along with diurnal cumulus clouds
should dissipate later this evening due to the loss of daytime
heating. Mainly just some high level cloudiness remaining for the
late night and morning hours. Prevailing weak south-southwest
surface winds can be expected through the forecast period.

GKS

&&

.CLIMATE...
Issued at 326 PM CDT Fri May 25 2018

Memorial Day Weekend Temperature Records

                 Records Highs    Record High Mins

Saturday 5/26
    St. Louis      98 (1953)         75 (2012)
    Columbia       93 (1953)         71 (1953)
    Quincy         95 (1911)         74 (1914)

Sunday   5/27
    St. Louis      93 (2012)         76 (2012)
    Columbia       92 (2012)         70 (2006)
    Quincy         94 (1911)         73 (1914)

Monday   5/28
    St. Louis      94 (2012)         76 (2012)
    Columbia       91 (2012)         72 (2012)
    Quincy         94 (1914)         72 (2012)


&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX



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