Special Weather Statement, NWS Jackson, MS

Area Forecast Discussion
National Weather Service Jackson MS
1005 AM CDT Sat Jul 17 2021

.UPDATE...
Updated for morning discussion.

&&

.DISCUSSION...
An early start to our convection has occurred this morning as an
overnight MCV has dropped south into the general vicinity. This
has helped to sustain convection across the Delta this morning and
portions of southeast Arkansas, stretching east into portions of
north central Mississippi. While some of this rain has been moving
over the same areas, it does appear to be more or less progressive
and the rates are not exceptionally high yet this morning. In
addition, portions of this region are surprisingly "lacking" in
rainfall compared to other parts of the CWA. However, we will
continue to monitor for the flash flood potential with any storms
that occur throughout the day. Looking at the bigger picture,
today will feature another day of greater coverage of storms as
was the case yesterday. This comes as the upper trough axis
resides in the vicinity/overhead of the forecast area and we are
on the western edge of a surface high pressure. This has brought
southerly flow to the region which has allowed moisture to better
infiltrate the region. Precipitable water values off the 12Z KJAN
sounding show around 2 inches and this is forecast to be around 2
to 2.3 inches through the day. This will mean that any storms that
occur will have the potential for efficient, heavy rainfall
similar to yesterday and can lead to localized flash flooding
concerns. My inclination, despite it being the summer season and
we can handle water better, is to outlook some kind of limited
flooding risk area. However, I am not confident in where exactly
as the entire area has that risk. Given the presence of this MCV,
there remains some flow across the area which should help reduce
the risk of storms lingering too long, but the greater coverage
suggests multiple rounds of storms in some locations will be
possible. Will continue to ponder this through the rest of this
morning.

In terms of severe weather, I won't rule out a strong
storm but like was the case yesterday, the potential for severe
storms is not high. While not a true microburst day today, several
parameters were lacking for severe weather to be a high concern.
However, with the presence of some forcing feature, daytime
heating, ample moisture, some cooler air aloft...it won't be
completely out of the question for some strong storms and perhaps
a couple severe storms this afternoon.

Otherwise, it should be a day mixed of some sun and many clouds.
Temperatures will be on the cooler side because of the rain and
clouds and should be in the 80s overall. /28/

Prior discussion below:

Today and Tonight...High pressure at the surface remains wedged into
the region from the east, while troughing aloft sits over the
region.  As the trough axis shifts east through the forecast area
today, a wave of ascent will likewise traverse the CWA through the
course of the day.  This ascent, coupled with daytime heating and a
moist unstable airmass, in addition to any lingering outflow
boundaries from Friday's convection, and a known remnant MCV
currently residing over extreme Southeast Arkansas, will all aid in
sparking numerous to widespread showers and storms across the
forecast area from late this morning through the afternoon hours.

The overall threat for severe storms is currently far too low to
introduce the mention of them into the HWO on this morning's
package.  However, a few storms could become intense enough to
produce wind gusts around 40 mph.  Frequent lightning strikes and
torrential downpours can both be expected with today's convection.
Some localized flash flooding could become possible as well as
rainfall rates will be quite high.  Convection will also be slow-
moving and storms could train across the same locations in a short
amount of time.

Convection will gradually dissipate during the evening.  An overall
lull in activity is expected through much of the overnight hours.
However, another area of ascent embedded in northwest flow aloft,
could begin sparking more showers and possible storms across
northern portions of the CWA by sunrise Sunday morning. /19/

Next week...The two words that best sum up this forecast period
are...more rain. Through Monday, we'll remain under a
northwesterly upper flow pattern, notorious for bringing periodic
disturbances with attendant convective complexes, potentially even
during the nighttime which is why we'll have to maintain somewhat
higher rain chances at night during the early part of the week.
The longwave upper trough over the eastern CONUS will shift
slightly eastward toward the middle of the week, but a narrow
trough axis will continue to extend through the Deep South even as
it does so. Guidance has been teasing out the potential for an
upper low feature cutting off from this trough, but regardless of
whether and when that happens, it appears likely we'll still
remain under negative height anomalies. At the surface, a high
will build over the Midwest, but we'll remain on the more active,
and notably moist (PW lingering near 2"), southern periphery of
this ridge. The ridge might be strong enough to curtail rain
chances somewhat across north MS and AR mid to late week, but for
most of the area, it appears we'll remain stuck in the wetter than
usual pattern.

Toward the end of the week, mid/upper ridging from the western US
shows signs of building toward our area. This may result in an
upward trend in temps by Friday, highly dependent upon rain
development/timing each day. Still, available guidance keeps a very
moist airmass in place across the region, so rain chances will
remain above normal through the end of the work week. Looking
farther ahead, there are signs that next weekend into the following
week, ridging will become dominant enough to finally trend back
toward more typical, drier July weather.

Any threat for stronger storms each day will be driven by mesoscale
influences difficult to anticipate very far ahead of time, given the
lack of more coherent deep shear anticipated. It's certainly
possible we could see a few storms produced damaging wind throughout
the week, including a convective complex or two early in the week
while we're in the northwesterly flow regime. In addition, we also
cannot rule out a localized flash flooding threat just about any day
during the upcoming week given the moist airmass and weak flow
regime, as we've already seen in recent days. /DL/

&&

.AVIATION...
12Z TAF discussion:
Thanks to low ceilings, patchy fog, and isolated to scattered
convection, a mix of VFR, MVFR, and IFR flight categories continue
to exist at TAF sites this morning. While ceilings will improve a
bit, they'll remain at VFR/MVFR status through the morning and
into this afternoon. Convection will again plague most sites
across the area now through the early evening hours. Torrential
downpours, gusty winds, and frequent lightning strikes can all be
expected with the most intense storms, if observed within a site's
respected aerodrome. Away from convection, winds today will be
from the southwest between 3-8 knots. /19/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       87  72  87  72 /  82  45  89  65
Meridian      87  71  86  71 /  89  42  89  64
Vicksburg     88  73  89  73 /  84  46  85  65
Hattiesburg   88  72  88  73 /  83  22  86  45
Natchez       88  72  89  73 /  78  26  80  53
Greenville    86  71  89  71 /  95  57  90  69
Greenwood     86  71  88  71 /  89  56  91  68

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.

&&

28

Hazardous Weather Outlook
National Weather Service Jackson MS
330 AM CDT Sat Jul 17 2021

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
172000-
Ashley-Chicot-Morehouse-West Carroll-East Carroll-Richland-
Madison LA-Franklin LA-Catahoula-Tensas-Concordia-Bolivar-
Sunflower-Leflore-Grenada-Carroll-Montgomery-Webster-Clay-Lowndes-
Choctaw-Oktibbeha-Washington-Humphreys-Holmes-Attala-Winston-
Noxubee-Issaquena-Sharkey-Yazoo-Madison MS-Leake-Neshoba-Kemper-
Warren-Hinds-Rankin-Scott-Newton-Lauderdale-Claiborne-Copiah-
Simpson-Smith-Jasper-Clarke-Jefferson-Adams-Franklin MS-Lincoln-
Lawrence-Jefferson Davis-Covington-Jones-Marion-Lamar-Forrest-
330 AM CDT Sat Jul 17 2021

This hazardous weather outlook is for portions of southeast
Arkansas, northeast Louisiana, central Mississippi, north central
Mississippi, and south central Mississippi.

.DAY ONE...Today and Tonight...

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Sunday through Friday...

The probability for widespread hazardous weather is low.

.SPOTTER CALL TO ACTION STATEMENT...
The activation of storm spotters, HAM radio operators, and
emergency management personnel in support of severe weather
operations is not expected through next Friday.

19

&&

...HAZARD LEGEND...

No short term hazards expected.

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   https://www.nhc.noaa.gov/
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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE JACKSON MS
1103 AM CDT SAT JUL 17 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0445 PM     FLASH FLOOD      2 E TOUGALOO            32.40N 90.13W
07/16/2021                   HINDS              MS   PUBLIC

            HOME WITH FLOODING IN NORTH EAST JACKSON, ON
            NORTH LAKE CIRCLE WAS REPORTED. AN ESTIMATED
            AMOUNT OF ABOUT 4 INCHES WAS GIVEN.

&&

JNE

Special Weather Statement
National Weather Service Jackson MS
1123 AM CDT Sat Jul 17 2021

MSZ043-049-171715-
Rankin MS-Madison MS-
1123 AM CDT Sat Jul 17 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN RANKIN AND SOUTHEASTERN
MADISON COUNTIES UNTIL 1215 PM CDT...

At 1123 AM CDT, Meteorologists were tracking a strong thunderstorm
near Canton, moving south at 20 mph.

Wind gusts up to 50 mph will be possible with this storm.

This strong thunderstorm will be near...
  Madison and Goshen Springs around 1140 AM CDT.
  Pisgah around 1145 AM CDT.
  Fannin around 1150 AM CDT.
  Pelahatchie around 1215 PM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

High winds can bring down trees and large limbs resulting in serious
injury or property damage. Exercise extreme caution when outdoors
during such strong winds...and be especially aware of older trees.

&&

LAT...LON 3228 9016 3229 9015 3231 9016 3232 9015
      3234 9011 3236 9011 3236 9010 3238 9010
      3240 9007 3240 9018 3265 9021 3271 8975
      3262 8975 3258 8978 3238 8973 3232 8973
TIME...MOT...LOC 1623Z 346DEG 19KT 3255 9001

JC

Special Weather Statement
National Weather Service Jackson MS
1141 AM CDT Sat Jul 17 2021

MSZ045-050-051-171715-
Scott MS-Newton MS-Neshoba MS-
1141 AM CDT Sat Jul 17 2021

...A STRONG THUNDERSTORM WILL AFFECT NEWTON...EAST CENTRAL SCOTT AND
SOUTHWESTERN NESHOBA COUNTIES UNTIL 1215 PM CDT...

At 1141 AM CDT, Meteorologists were tracking a strong thunderstorm
near Conehatta, or near Prospect, moving east at 15 mph.

Dime size hail and winds in excess of 40 mph will be possible with
this storm.

This strong thunderstorm will be near...
  Stratton around 1155 AM CDT.
  Decatur around 1205 PM CDT.
  Newton and Little Rock around 1215 PM CDT.

Other locations impacted by this storm include Chunky and Hickory.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

High winds can bring down trees and large limbs resulting in serious
injury or property damage. Exercise extreme caution when outdoors
during such strong winds...and be especially aware of older trees.

&&

LAT...LON 3226 8892 3239 8941 3269 8925 3257 8891
TIME...MOT...LOC 1641Z 291DEG 13KT 3248 8921

JNE