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000
FXUS63 KLSX 301945
AFDLSX

Area Forecast Discussion
National Weather Service Saint Louis MO
245 PM CDT MON MAY 30 2016

.SHORT TERM...  (Through Late Tonight)
Issued at 244 PM CDT Mon May 30 2016

Getting isolated showers/storms this afternoon across parts of the
forecast area with diurnal heating and instability.  More
significant is the convection across southwest MO associated with an
MCV.  This convection will likely move into parts of central and
southeast MO late this afternoon and early this evening.  A few
storms may be strong to severe in central MO late this afternoon and
early this evening.  Although the convection should weaken in
intensity later this evening as the atmosphere stabilizes with
nocturnal cooling, some of this activity may continue to push
northeastward into much of our forecast area overnight.  Low
temperatures should be a little warmer than the previous night due
to increased cloud cover and a return to low level southerly winds.

GKS

.LONG TERM...  (Tuesday through Next Monday)
Issued at 244 PM CDT Mon May 30 2016

Storm chances will be on the increase Tuesday as cold front moves
into northwestern MO by midday. Highs on Tuesday hard to pin down as
it will depend on cloud cover and precipitation. For now, they will
be a bit above normal in the low to mid 80s. Will see several rounds
of storms with best chances Tuesday night and Wednesday as front
moves through forecast area. Some decent instability and lift along
boundary, but it will be marginal especially over southeast MO and
southwestern IL. So SPC has a marginal risk over southeast half of
forecast area on Wednesday.

Rain to taper off on Thursday with drier weather through Friday as
weak ridging builds in. However, next system to approach region for
the weekend but timing hard to pin down, so kept slight chance pops
for Saturday and Sunday. Temperatures will be near normal through
the extended.

Byrd
&&

.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1126 AM CDT Mon May 30 2016

Scattered diurnal cumulus clouds will develop this afternoon.
There should be isolated showers/storms late this afternoon and
early this evening, but for most sites the probability of
precipitation looks too low to include in the tafs. The one
exception may be COU where showers/storms moving into southwestern
MO associated with an upper level disturbance may move into COU
by evening or overnight. Mainly just mid-high level cloudiness
expected for tonight. Weak south-southeasterly surface winds can
be expected this afternoon as the surface ridge shifts east of the
area. Surface winds will become light this evening, then
strengthen on Tuesday.

Specifics for KSTL: Scattered diurnal cumulus clouds will develop
this afternoon. Could not rule out an isolated shower/storm late
this afternoon or early this evening, but it appears that the
better chance for convection will be Tuesday afternoon. For now
will keep the STL taf dry this afternoon and tonight, but include
VCTS Tuesday afternoon. Mainly just mid-high level cloudiness
tonight, then diurnal cumulus clouds will develop again late
Tuesday morning and afternoon. Southwest surface wind will become
more southeasterly this afternoon, then light this evening.
Southeasterly surface wind will strengthen to around 8 kts Tuesday
afternoon.

GKS
&&

.PRELIMINARY POINT TEMPS/POPS...
Saint Louis     66  85  67  81 /  20  30  50  70
Quincy          64  83  64  79 /  30  50  70  60
Columbia        63  81  63  78 /  30  50  70  60
Jefferson City  63  82  64  78 /  40  50  70  70
Salem           64  85  65  82 /  20  20  30  70
Farmington      62  81  63  80 /  20  30  40  70

&&

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

$$
WFO LSX





000
FXUS63 KLSX 301652
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1152 AM CDT MON MAY 30 2016

.SHORT TERM...  (Through Late This Afternoon)
Issued at 405 AM CDT Mon May 30 2016

A surface warm front extends from northeast Nebraska to northeast
Missouri early this morning and is moving very slowly to tbe east.
Isolated to scattered thunderstorms have developed near and
east of this warm front from the WAA aloft.  Otherwise, skies were
mostly clear across the rest of our region with temps mainly in the
60s, with some pockets of 50s in the valley areas of the eastern
Ozarks, and the urban heat island of STL still holding on to some
lower 70s.

The situation with the warm front will likely persist to some degree
thru mid-morning, maintaining the threat for isolated showers and
thunderstorms in parts of northeast MO and west-central IL.
Otherwise, things should reset by late this morning with the models
advertising a very weak shear, low-moderate CAPE, no CINH
environment with any focus, surface-based or aloft, hard to come by.
Discrete models are all suggesting the potential for a few showers
and thunderstorms this afternoon with virtually no distinguishment
for one area over another given lack of a discernable focus.  With
this in mind, went slight chance PoPs for most of the forecast area
this afternoon for potential of "airmass" type thunderstorms.
Severe potential should be low given the environmental setup.

For much of today, should see decent sunshine for most areas with a
weak southeast to south flow developing as the surface warm front
moves thru.  Should see max temps at or above persistence, yielding
readings in the upper 80s to around 90.

TES

.LONG TERM...  (Tonight through Sunday)
Issued at 405 AM CDT Mon May 30 2016

Tonight - Wed night

Upper lvl flow will become increasingly more SWrly thru the week as
a short wave strengthens across the ntrhn Plains Mon night/Tue. Even
though there is largely a lack of focus or forcing thru Tue...expect
isld/scttrd precip in the warm moist SW flow. One thing to watch is
the upper lvl system driving the convection across TX tonight. Most
guidance tracks it E or NE today...keeping it just S of the CWA
but...the ECMWF and NAM actually bring the core of that feature
across the CWA tonight. That scenario would obviously create far
different conditions that the current fcst indicates. This is
something the day shift will have to monitor for potential
significant fcst adjustments. This feature will drive a cold front
thru the region Wed/Wed night. A portion of the CWA is outlooked for
a marginal risk of SVR TSTMs on Wed. This would appear appropriate
due to less than 30 kts of shear. Temps should be aoa normal.

Thu - Sun

There is a low potential for a few post frontal SHRAs across SE MO
and sthrn IL on Thu but think most locations will remain dry. SFC
high pressure is fcst to build into the region for the end of the
week providing the area at least one dry day on Fri. Guidance
suggests significant troughs dvlpng along the Coasts with a high
amplitude ridge aligned along the Rockies over the wknd which puts
the...FA in NW flow. Differences exist in timing of short waves over
the wknd assoc with reinforcing shots of cold air and precip
chances. Temps should be near normal.

2%

&&

.AVIATION...  (For the 18z TAFs through 18z Tuesday Afternoon)
Issued at 1126 AM CDT Mon May 30 2016

Scattered diurnal cumulus clouds will develop this afternoon.
There should be isolated showers/storms late this afternoon and
early this evening, but for most sites the probability of
precipitation looks too low to include in the tafs. The one
exception may be COU where showers/storms moving into southwestern
MO associated with an upper level disturbance may move into COU
by evening or overnight. Mainly just mid-high level cloudiness
expected for tonight. Weak south-southeasterly surface winds can
be expected this afternoon as the surface ridge shifts east of the
area. Surface winds will become light this evening, then
strengthen on Tuesday.

Specifics for KSTL: Scattered diurnal cumulus clouds will develop
this afternoon. Could not rule out an isolated shower/storm late
this afternoon or early this evening, but it appears that the
better chance for convection will be Tuesday afternoon. For now
will keep the STL taf dry this afternoon and tonight, but include
VCTS Tuesday afternoon. Mainly just mid-high level cloudiness
tonight, then diurnal cumulus clouds will develop again late
Tuesday morning and afternoon. Southwest surface wind will become
more southeasterly this afternoon, then light this evening.
Southeasterly surface wind will strengthen to around 8 kts Tuesday
afternoon.

GKS

&&

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

$$

WFO LSX





000
FXUS63 KLSX 300441
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1141 PM CDT SUN MAY 29 2016

.UPDATE...
Issued at 916 PM CDT Sun May 29 2016

Showers and thunderstorms have developed this evening over
northeast Missouri in an area of weak low level moisture
convergence seen on the RAP. Latest objective analysis shows this
area has near 2000 J/kg MUCAPE and 30kts of effective shear.
Expect these storms to gradually weaken later this evening as the
low level ridge move across the area causing the convergence to
weaken. Otherwise, will increase cloud cover with convective debris
moving into the area from the Plains. Lows tonight still look on
track.

Britt

&&

.SHORT TERM...  (Through Late Tonight)
Issued at 248 PM CDT Sun May 29 2016

Scattered diurnal cumulus field has developed across much of the
forecast area this afternoon.  Could not rule out an isolated shower
across southeast MO and southwest IL late this afternoon where there
is a little better low level moisture and instability, but will
leave the forecast dry for now as the probability is very low.  The
cumulus clouds should dissipate early this evening due to the loss
of daytime heating.  There will likely be some high level clouds
tonight.  Discounting the GFS model which has light QPF and chance
pops over northeast MO late tonight.  It does not appear that there
will be enough forcing or moisture to generate any precipitation
late tonight, and will go with the dry solutions of the NAM and
ECMWF models. The surface wind will become light or even calm this
evening with a surface ridge over our area. There should be enough
radiational cooling to allow temperatures to drop into the lower 60s
late tonight/early Monday morning over most of the area with a few
spots in the upper 50s for lows.

GKS

.LONG TERM...  (Monday through Next Sunday)
Issued at 248 PM CDT Sun May 29 2016

Most of the holiday will be dry, but low level flow will bring
moisture back into the region with rain chances increasing as the
day progresses and first in a series of shortwaves slide through
area. So have slight chance/pops mainly for areas along and west
of Mississippi River. Highs will be in the mid to upper 80s
Monday.

Rounds of activity to persist through midweek with best chances of
storms Tuesday night and Wednesday, so have likely pops for most of
forecast area. Have some decent CAPES on Wednesday with frontal
boundary moving through, but it is still too far out to determine if
we will see any severe weather by mid week. Highs through midweek
will be in the in the upper 70s to mid 80s.

Then cold front to exit region bringing in slightly cooler and drier
wx through at least Saturday. However, highs will still be near
normal, in the mid to upper 70s. Could see wet pattern return for
next Sunday, but for now just kept slight chance/low end chance pops
at this time.

Byrd

&&

.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 1137 PM CDT Sun May 29 2016

Isolated showers and thunderstorms continue to be generated across
northeast Missouri into west central Illinois late this evening. A
few of these may affect KUIN through 08Z. Mainly dry and VFR
weather is expected through the rest of the period at the TAF
period. Only exception may occur at KCOU tomorrow when scattered
showers move into central Missouri during the afternoon. Have
included a VCSH to accommodate this risk.

Specifics for KSTL: Dry and VFR conditions are expected the next
30 hours.

Britt

&&

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

$$

WFO LSX





000
FXUS63 KLSX 280452
AFDLSX

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1152 PM CDT FRI MAY 27 2016

.UPDATE...
Issued at 951 PM CDT Fri May 27 2016

One area of showers and isolated thunderstorms have currently moved
into the northern CWA while another small area of showers are
moving into east central Missouri from southeast Missouri. These
areas of rain continue to be generated in pockets of low level
moisture convergence ahead of at shortwave trough currently over
the southern Plains. The latest RAP shows that this trough will
move northeast toward Missouri and Illinois toward morning. Will
keep going chance of showers and thunderstorms through the night
ahead of the upper trough.

Going lows in the mid to upper 60s still look good.

Britt

&&

.SHORT TERM...  (Through Late Tonight)
Issued at 305 PM CDT Fri May 27 2016

Showers and thunderstorms were developing and spreading back
northward into our area ahead of the upper level low over eastern
CO and western KS, and northeast of a shortwave approaching from
the southern Plains. These showers/storms should impact most of
the forecast area this evening, possibly continuing into the late
night hours. Mild temperatures can be expected again tonight due
to the cloud cover, relatively high surface dew points, and
southerly winds.

GKS

.LONG TERM...  (Saturday through Next Friday)
Issued at 305 PM CDT Fri May 27 2016

The threat for showers/storms will continue on Saturday and
Saturday night as the negatively tilted upper level trough moves
northeastward through the area. Should finally get a dry period
from Sunday into at least early Monday as the upper level trough
shifts northeast of our area with a weak surface ridge moving
eastward through the region after the passage of a weak surface
trough. Convection should return by Monday afternoon or night to
much of the area as a warm and moist southerly flow returns as the
surface ridge shifts east of our area, while weak southwest flow
shortwaves move through the region. The ECMWF and GFS model
solutions diverge after the Memorial Day weekend. The ECMWF model
has a strong upper level trough moving eastward through the
northern Plains which sends a cold front southeastward through our
forecast area late Tuesday night and Wednesday with convection
along and ahead of this front, followed by cooler and drier
weather by Thursday night. The GFS model keeps us in southwest
upper level flow with a slow moving upper level low developing
over the central Plains. The GFS solution would keep the chance of
convection going through the entire extended forecast. The ECMWF
model solution looks more realistic for this time of the year.
For now will reduce pops by Thursday night, but keep slight chance
pops going through the end of the forecast.

GKS

&&

.AVIATION...  (For the 06z TAFs through 06z Saturday Night)
Issued at 1135 PM CDT Fri May 27 2016

MVFR ceilings currently over parts of the area are expected to
spread across the area through 10Z. These ceiling are expected to
rise to VFR by mid morning.  Scattered showers and thunderstorms
will remain possible through the TAF period with the greatest
chance during the afternoon and early evening hours on Saturday.
Any thunderstorm could produce heavy downpours with MVFR or IFR
ceilings and visibilities.

Specifics for KSTL: MVFR ceilings are expected to develop between
09-15Z. There is a chance of showers and thunderstorms through
the TAF period with the greatest chance during the late afternoon
and early evening hours on Saturday. Any thunderstorm could
produce heavy downpours with MVFR or IFR ceilings and
visibilities.

Britt

&&

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

$$

WFO LSX





000
FXUS63 KLSX 280251
AFDLSX

Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
951 PM CDT FRI MAY 27 2016

.UPDATE...
Issued at 951 PM CDT Fri May 27 2016

One area of showers and isolated thunderstorms have currently moved
into the northern CWA while another small area of showers are
moving into east central Missouri from southeast Missouri. These
areas of rain continue to be generated in pockets of low level
moisture convergence ahead of at shortwave trough currently over
the southern Plains. The latest RAP shows that this trough will
move northeast toward Missouri and Illinois toward morning. Will
keep going chance of showers and thunderstorms through the night
ahead of the upper trough.

Going lows in the mid to upper 60s still look good.

Britt

&&

.SHORT TERM...  (Through Late Tonight)
Issued at 305 PM CDT Fri May 27 2016

Showers and thunderstorms were developing and spreading back
northward into our area ahead of the upper level low over eastern
CO and western KS, and northeast of a shortwave approaching from
the southern Plains. These showers/storms should impact most of
the forecast area this evening, possibly continuing into the late
night hours. Mild temperatures can be expected again tonight due
to the cloud cover, relatively high surface dew points, and
southerly winds.

GKS

.LONG TERM...  (Saturday through Next Friday)
Issued at 305 PM CDT Fri May 27 2016

The threat for showers/storms will continue on Saturday and
Saturday night as the negatively tilted upper level trough moves
northeastward through the area. Should finally get a dry period
from Sunday into at least early Monday as the upper level trough
shifts northeast of our area with a weak surface ridge moving
eastward through the region after the passage of a weak surface
trough. Convection should return by Monday afternoon or night to
much of the area as a warm and moist southerly flow returns as the
surface ridge shifts east of our area, while weak southwest flow
shortwaves move through the region. The ECMWF and GFS model
solutions diverge after the Memorial Day weekend. The ECMWF model
has a strong upper level trough moving eastward through the
northern Plains which sends a cold front southeastward through our
forecast area late Tuesday night and Wednesday with convection
along and ahead of this front, followed by cooler and drier
weather by Thursday night. The GFS model keeps us in southwest
upper level flow with a slow moving upper level low developing
over the central Plains. The GFS solution would keep the chance of
convection going through the entire extended forecast. The ECMWF
model solution looks more realistic for this time of the year.
For now will reduce pops by Thursday night, but keep slight chance
pops going through the end of the forecast.

GKS

&&

.AVIATION...  (For the 18z TAFs through 18z Saturday Afternoon)
Issued at 1238 PM CDT Fri May 27 2016

Difficult forecast regarding precipitation trends for this valid
TAF period. Believe chances for showers and thunderstorms will
increase this afternoon into very early evening ahead of next
shortwave. Could be a lull tonight with another wave late
tonight/early on Saturday possible. Other concern in the near term
is the MVFR ceilings but expect only a short period of these
ceilings before they lift into VFR.

Specifics for KSTL:

MVFR ceilings likely next few hours. Scattered showers and storms
also expected to increase this afternoon ahead of next shortwave
trough. Convective trends become more ambiguous overnight tonight
and into the day on Saturday.

Gosselin

&&

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

$$

WFO LSX





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