Flood Watch 2, NWS St. Louis, MO

791 
WGUS63 KLSX 020830
FFALSX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service St Louis MO
230 AM CST Thu Mar 2 2023

ILZ069-070-074-101-102-MOZ065-022330-
/O.EXA.KLSX.FA.A.0002.230303T0000Z-230303T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Clinton IL-Marion IL-Washington IL-Saint Clair-Monroe IL-
Jefferson MO-
Including the cities of Belleville, Salem, Cahokia, and Centralia
230 AM CST Thu Mar 2 2023

...FLOOD WATCH IN EFFECT FROM THIS EVENING THROUGH FRIDAY MORNING...

* WHAT...Flooding caused by excessive rainfall continues to be 
  possible.

* WHERE...Portions of Illinois, including the following areas, 
  Clinton IL, Marion IL, Monroe IL, Saint Clair and Washington IL. 
  Portions of east central Missouri, including the following area, 
  Jefferson MO.

* WHEN...From this evening through Friday morning.

* IMPACTS...Excessive runoff may result in flooding of rivers, 
  creeks, streams, and other low-lying and flood-prone locations. 
  Creeks and streams may rise out of their banks.

* ADDITIONAL DETAILS...
  - Total rainfall amounts of 1 to 3 inches can be expected
    throughout the Watch area, with locally higher amounts
    possible.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be alert for possible Flood 
Warnings. Those living in areas prone to flooding should be prepared 
to take action should flooding develop.

&&

$$

ILZ079-MOZ072>075-084-085-099-022330-
/O.CON.KLSX.FA.A.0002.230303T0000Z-230303T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Randolph IL-Crawford MO-Washington MO-Saint Francois MO-Sainte
Genevieve MO-Iron MO-Madison MO-Reynolds MO-
Including the cities of Farmington, Chester, and Sparta
230 AM CST Thu Mar 2 2023

...FLOOD WATCH REMAINS IN EFFECT FROM THIS EVENING THROUGH FRIDAY 
MORNING...

* WHAT...Flooding caused by excessive rainfall continues to be 
  possible.

* WHERE...Portions of southwest Illinois, including the following 
  area, Randolph IL. Portions of Missouri, including the following 
  areas, Crawford MO, Iron MO, Madison MO, Reynolds MO, Saint 
  Francois MO, Sainte Genevieve MO and Washington MO.

* WHEN...From this evening through Friday morning.

* IMPACTS...Excessive runoff may result in flooding of rivers, 
  creeks, streams, and other low-lying and flood-prone locations. 
  Creeks and streams may rise out of their banks.

* ADDITIONAL DETAILS...
  - Total rainfall amounts of 1 to 3 inches can be expected
    throughout the Watch area, with locally higher amounts
    possible.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be alert for possible Flood 
Warnings. Those living in areas prone to flooding should be prepared 
to take action should flooding develop.

&&

$$

Gosselin

665 
WGUS63 KLSX 022057
FFALSX

Flood Watch
National Weather Service St Louis MO
257 PM CST Thu Mar 2 2023

ILZ069-070-074-079-101-102-MOZ065-072>075-084-085-099-031800-
/O.CON.KLSX.FA.A.0002.230303T0000Z-230303T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Clinton IL-Marion IL-Washington IL-Randolph IL-Saint Clair-Monroe
IL-Jefferson MO-Crawford MO-Washington MO-Saint Francois MO-
Sainte Genevieve MO-Iron MO-Madison MO-Reynolds MO-
Including the cities of Sparta, Salem, Belleville, Centralia,
Chester, Cahokia, and Farmington
257 PM CST Thu Mar 2 2023

...FLOOD WATCH REMAINS IN EFFECT FROM 6 PM CST THIS EVENING THROUGH 
FRIDAY MORNING...

* WHAT...Flooding caused by excessive rainfall continues to be 
  possible.

* WHERE...Portions of Illinois, including the following areas, 
  Clinton IL, Marion IL, Monroe IL, Randolph IL, Saint Clair and 
  Washington IL. Portions of Missouri, including the following 
  areas, Crawford MO, Iron MO, Jefferson MO, Madison MO, Reynolds 
  MO, Saint Francois MO, Sainte Genevieve MO and Washington MO.

* WHEN...From 6 PM CST this evening through Friday morning.

* IMPACTS...Excessive runoff may result in flooding of rivers, 
  creeks, streams, and other low-lying and flood-prone locations. 
  Creeks and streams may rise out of their banks.

* ADDITIONAL DETAILS...
  - Total rainfall amounts of 1 to 3 inches can be expected
    throughout the Watch area, with locally higher amounts
    possible.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be alert for possible Flood 
Warnings. Those living in areas prone to flooding should be prepared 
to take action should flooding develop.

&&

$$

19

880 
WGUS63 KLSX 030903
FFALSX

Flood Watch
National Weather Service St Louis MO
303 AM CST Fri Mar 3 2023

ILZ069-070-074-079-101-102-MOZ065-072>075-084-085-099-031800-
/O.CON.KLSX.FA.A.0002.000000T0000Z-230303T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Clinton IL-Marion IL-Washington IL-Randolph IL-Saint Clair-Monroe
IL-Jefferson MO-Crawford MO-Washington MO-Saint Francois MO-
Sainte Genevieve MO-Iron MO-Madison MO-Reynolds MO-
Including the cities of Salem, Sparta, Chester, Farmington,
Centralia, Cahokia, and Belleville
303 AM CST Fri Mar 3 2023

...FLOOD WATCH REMAINS IN EFFECT UNTIL NOON CST TODAY...

* WHAT...Flooding caused by excessive rainfall continues to be 
  possible through this morning.

* WHERE...Portions of Illinois, including the following areas, 
  Clinton IL, Marion IL, Monroe IL, Randolph IL, Saint Clair and 
  Washington IL. Portions of Missouri, including the following 
  areas, Crawford MO, Iron MO, Jefferson MO, Madison MO, Reynolds 
  MO, Saint Francois MO, Sainte Genevieve MO and Washington MO.

* WHEN...Until Noon CST today.

* IMPACTS...Excessive runoff may result in flooding of rivers, 
  creeks, streams, and other low-lying and flood-prone locations. 
  Creeks and streams may rise out of their banks.

* ADDITIONAL DETAILS...
  - Total rainfall amounts of 1 to 3 inches can be expected
    throughout the Watch area, with locally higher amounts
    possible.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be alert for possible Flood 
Warnings. Those living in areas prone to flooding should be prepared 
to take action should flooding develop.

&&

$$

Britt

882 
WGUS63 KLSX 031805
FFALSX

Flood Watch
National Weather Service St Louis MO
1205 PM CST Fri Mar 3 2023

ILZ069-070-074-079-101-102-MOZ065-072>075-084-085-099-031915-
/O.EXP.KLSX.FA.A.0002.000000T0000Z-230303T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Clinton IL-Marion IL-Washington IL-Randolph IL-Saint Clair-Monroe
IL-Jefferson MO-Crawford MO-Washington MO-Saint Francois MO-
Sainte Genevieve MO-Iron MO-Madison MO-Reynolds MO-
Including the cities of Farmington, Chester, Salem, Cahokia,
Centralia, Belleville, and Sparta
1205 PM CST Fri Mar 3 2023

...FLOOD WATCH HAS EXPIRED...

The Flood Watch has expired for portions of Illinois, including the 
following areas, Clinton IL, Marion IL, Monroe IL, Randolph IL, 
Saint Clair and Washington IL. Portions of Missouri, including the 
following areas, Crawford MO, Iron MO, Jefferson MO, Madison MO, 
Reynolds MO, Saint Francois MO, Sainte Genevieve MO and Washington 
MO.

Rain rates have diminished and are expected to continue to decrease. 
Therefore, the Flood Watch has been allowed to expire.

$$

BRC

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1138 AM CST Wed Mar 1 2023

.SHORT TERM...  (Through Late Thursday Afternoon)
Issued at 258 AM CST Wed Mar 1 2023

A subtle warm front was located a KMBY>>KPPQ>KSPI axis as of 0800
UTC and should move a bit more northward before washing out.
Along and immediately north of this feature, some fog has
developed in northeast Missouri and west-central Illinois. Some
further reduction in visibility is likely over the next few hours,
but we are not expecting any dense fog at this time. A weak wave
of low pressure is forecast to ride along the warm front later
today, with its trailing cold front moving through the CWA late
this morning into the afternoon hours. The timing of this cold
front has sped up about 1-2 hours from what it looked like
yesterday. Consequently, PoPs have been lowered in southeast
Missouri and southwest Illinois. Now only isolated showers (and
potentially a rumble of thunder) are expected in far southern
sections of the CWA, mainly between 5 and 9 PM. A slower frontal
passage may have helped provide just enough instability for a
strong storm or two, but the aforementioned faster timing looks to
have closed the door on this possibility. Latest HREF guidance
only shows about a 10-20% chance of at least 500 J/kg of surface-
based CAPE, down from about 30-40% from the previous run.

Temperatures today will be warmer than normal, particularly in
southeast Missouri and southwest Illinois where the front will not
pass through until near 2100 UTC. Low to mid 70s are forecast in
these locations. Further northwest, temperatures gradually cool, all
the way back into the mid 50s for northeast Missouri and west-
central Illinois where low-level cold air advection intensifies
through the day.

Behind the front, cooler air will move into the region tonight and
into Thursday. Low temperatures tonight are forecast to be mostly in
the 30s, with highs on Thursday about 10-15 degrees cooler than this
afternoon. Increasing clouds are expected on Thursday ahead of the
powerful storm system which will impact the mid-Mississippi Valley
beginning early Thursday evening.

Gosselin

.LONG TERM...  (Thursday Night through Tuesday)
Issued at 258 AM CST Wed Mar 1 2023

(Thursday Night - Friday)

Widespread rain should be entering southeast Missouri and southwest
Illinois by early Thursday evening as low-level moisture advection
intensifies and mid/upper level ascent increases ahead of the closed
low in the south-central Plains. Rainfall should be mostly moderate
intensity, though some brief periods of heavier rain are possible
after midnight. Heaviest rainfall rates are most likely in parts of
southeast Missouri and southwest Illinois where the strongest low-
level moisture convergence will reside, along with the possibility
at least of some convective elements. The dry slot should quickly
enter these locations Friday morning, which should end the
heavier rainfall in southeast Missouri and southwest Illinois.
Further northwest, models show a well-defined deformation zone
that will continue to produce precipitation through Friday
afternoon. Precipitation type becomes more of a question mark late
morning into the afternoon after the passage of the low-level
cyclone. The availability (or lack thereof) of just cold enough
air in the boundary layer for snow is uncertain. While strong
dynamics/heavy precipitation rates may be enough to help the rain
mix with or changeover to snow in northeast Missouri and west-
central Illinois, most deterministic guidance has trended warmer
for surface temperatures. Even the CMC, which has a consistent
cold bias, keeps surface temperatures too warm for snow. Given a
later timing of this system (precipitation within the deformation
zone falling during the daytime on Friday vs. late Thursday
night) and the surface low occluding and then weakening on Friday,
it definitely puts into question whether there will be any snow
in the CWA. However, given the strong dynamics and deep mid/upper
level closed low, there is still certainly that potential. If
rain can change over to snow, it very well may come down heavily
for at least a few hours which could cause problems. Long story
short, there is still potential for at least a few inches of a
very wet snow in our northwestern CWA, but chances have dropped
compared to 1-2 days ago.

By early Friday morning, the system should begin to occlude as the
mid/upper level low becomes vertically stacked over the surface low.
This should cease the strengthening of the surface low, with gradual
cyclolysis thereafter. However, by that time the surface low should
be between 980 and 985 hPa. While some members of the GEFS/EPS are
lower than that, the probability for below 980 hPa has decreased
compared to yesterday, with only about a 10-15% chance on the
grand ensemble. There is still quite a bit of uncertainty with
the exact track of the low (especially for this lead time). The
NAM/ECMWF/EPS are further northwest, with a track up the I-44
corridor of Missouri or just to the northwest. Meanwhile, the
GFS/GEFS/CMC are about 125 miles further southeast, with a track
through far southern Missouri into south-central Illinois. The
exact track will have impacts on where the heavier precipitation
within the deformation zone resides Friday, as well as where the
strongest winds will be.

By the time the precipitation ends, 1.00-2.50" of rainfall is
expected as you go from northwest to southeast. The GEFS remains
most bullish with the probabilities of at least 2.00", showing
around a 75 percent chance in parts of southeast Missouri and
southwest Illinois. The EPS is not as high, with a general 20-40%
chance over a broader area. Our main concern with this heavy QPF
event is on the likelihood for fairly widespread minor river
flooding. Cannot rule out some isolated moderate river flooding if
we end up seeing some higher rainfall totals, but at this time that
is likely to be the exception rather than the rule. The odds of
flash flooding continue to look quite low given high flash flood
values (2.00-2.50" in 3 hours), some dryness the past 7-14 days
where we have the highest rainfall totals (southeast Missouri and
southwest Illinois), and the expectation for little/no convection.
In addition, efficiency measures including warm cloud depths and
precipitable water values, while abnormally high, do not look extreme
for this upcoming event.

Speaking of winds, sustained speeds of 25-35 mph with gusts of 40-45
mph appear likely Thursday night into Friday. The setup is quite a
bit different than the high wind event we had on Monday, with much
more limited mechanical mixing. However, the pressure gradient is
obviously quite strong given the strength of the surface low. At
this time, advisory level (45+ mph) gusts are possible on Friday,
mainly in parts of southeast Missouri and southwest Illinois just to
the south/southwest of the track of the surface low. However, if the
further south solutions like the GFS/GEFS/CMC verifies, then these
gusts may stay to our southeast.

(Friday Night - Tuesday)

Dry weather along with generally near-normal temperatures is favored
this weekend. A warming trend is forecast into Monday as low-level
warm air advection ramps up ahead of an approaching cold front. This
front is likely to pass through the region by Monday night. This
front may pass through dry as moisture return ahead of the boundary
is fairly weak, with stronger mid/upper level ascent well to our
north across the Upper Midwest/Great Lakes. Uncertainty increases
heading into Tuesday as to exactly where the front stalls out. If it
stalls out near or just south of the area, rain chances would
continue on Tuesday. However, if the front settles far enough into
the mid south, then dry weather would be more favored. Regardless,
at least slightly cooler temperatures are forecast on Tuesday
compared to Monday.

Gosselin

&&

.AVIATION...  (For the 18z TAFs through 18z Thursday Afternoon)
Issued at 1136 AM CST Wed Mar 1 2023

VFR conditions are expected throughout the 18Z TAF cycle. A weak
cold front will shift winds to the northwest this afternoon, and
winds will slowly shift to the northeast by early tomorrow
morning. High level cloud cover will also increase gradually, but
precipitation is not expected to arrive until after 00Z Friday.

&&

.CLIMATE...
Issued at 312 PM CST Mon Feb 27 2023

Mean Sea Level Pressure (MSLP) Records:

March...
KSTL:  982.1 mb  (Mar 29, 1924)
KCOU:  979.0 mb  (Mar 29, 1924)

All Time...
KSTL:  976.0 mb  (Feb 27, 1958)
KCOU:  972.9 mb  (Feb 27, 1958)

&&

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

WFO LSX

Hazardous Weather Outlook
National Weather Service St Louis MO
311 AM CST Wed Mar 1 2023

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-020915-
Greene IL-Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL-
Marion IL-Washington IL-Randolph IL-Adams IL-Brown IL-Pike IL-
Calhoun IL-Jersey IL-Madison IL-Saint Clair-Monroe IL-Knox MO-
Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls MO-Pike MO-Boone MO-
Audrain MO-Moniteau MO-Cole MO-Osage MO-Callaway MO-Montgomery MO-
Lincoln MO-Gasconade MO-Warren MO-Saint Charles MO-Franklin MO-
Saint Louis MO-Saint Louis City MO-Jefferson MO-Crawford MO-
Washington MO-Saint Francois MO-Sainte Genevieve MO-Iron MO-
Madison MO-Reynolds MO-
311 AM CST Wed Mar 1 2023

This Hazardous Weather Outlook is for portions of eastern and
central Missouri as well as west central and southwest Illinois.

.DAY ONE...Today and tonight.

Isolated thunderstorms are possible early this evening in parts of
southeast Missouri.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Late Thursday and Friday, a strong storm system will have the
potential to produce heavy rainfall. The rain may change to
wet snow in northeastern Missouri and west-central Illinois on
Friday. Additionally, thunderstorms will be possible along and south
of Interstate 70 on Thursday night.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Gosselin