Special Weather Statement, NWS Jackson, MS

Area Forecast Discussion
National Weather Service Jackson MS
1250 PM CDT Wed Aug 9 2017

.UPDATE...
Updated for 18Z aviation discussion

&&

.AVIATION...
18Z TAF discussion:
Scattered TSRA coverage is slowly increasing around the region.
The southern and eastern sites will have the best chances of being
impacted by TSRA through this afternoon. There will be a slight
lull in TSRA/SHRA activity overnight before activity begins to
increase late in the TAF period, with better chances at the
western sites. A moist boundary layer will result in some patchy
fog overnight throughout the region.

&&

.DISCUSSION...
An axis of weak thunderstorm and shower activity still exists
along the US 84 corridor this morning. The best rainfall rates
have occurred in areas that haven't been as wet over the last few
days, resulting in less of an impact. Hi-res guidance, which has
been fairly conservative through this active period, is more
aggressive through the rest of today with convective storm
activity increasing as the day continues. The main threat with any
storms today will continue to be flash flooding as Pwats increase
to above 2.5" this afternoon. The most concerning locations will
be the locations that have received significant amounts of
rainfall over the past 24 to 48 hours. A flash flood watch will
remain in effect until 7 PM but may have to be extended a few
hours to account for ongoing convection as we approach it's
scheduled end time.

Prior discussion below:

Today and Tonight: Although afternoon temperatures will top out a
few degrees warmer today than they did Tuesday, cooler than normal
temperatures with above normal rain chances will continue again
today. Early morning surface analysis still had a nearly stationary
boundary near the interstate 20 corridor that will drift back north
today. This boundary will combine with an anomalously moist airmass
and daytime heating to produce widespread convection raising the
concern for the potential for flash flooding once again. The PWAT
across our CWA remains around 2.2inches. Convection is expected to
develop across our CWA later this morning and intensify during the
afternoon. Although locally heavy rainfall will be possible over our
whole CWA, the highest rainfall amounts are expected generally along
and north of Interstate 20. This is the same area that has seen the
bulk of the rain the last several days and where the current Flash
Flood Watch will remain in effect until 7PM this evening. Mid level
ridging from the eastern Gulf will strengthen and move west across
the northern Gulf later today and tonight. This should help result
in a distinct downward trend of convection this evening with the
loss of daytime heating although a slight chance of rain will
continue across our CWA again tonight. The persistent cloud cover
and rain will again hold afternoon temperatures well below normal.
Low temperatures tonight will bottom out again in the lower 70s
which is normal. /22/

Thursday through Tuesday: The Lower Mississippi Valley will remain
at the base of a broad upper trough over the eastern half of the
CONUS into next week. Through this time frame, disturbances will
traverse upper flow around this trough and over the tropical moist
airmass in place across the region. By Thursday, no organized front
is expected to remain over the area - only lingering boundaries from
recent convection. Nevertheless, convergence along these boundaries
in the the moisture rich airmass that remains will still result in
numerous showers and thunderstorms each day through the weekend,
particularly during the diurnally favorable portions of the day.
Over the weekend a more organized surface front will develop over
the Mid Mississippi and Ohio Valleys. It will make a southward push,
perhaps providing a sharper focus for convection at some point next
week. Generally speaking, daytime temps will remain slightly below
normal due to the increased prevalence of clouds and rain.

Though at least some flash flood potential will continue through
much of the forecast period due to abundant deep layer moisture and
antecedent saturated grounds from previous rain in some areas, we'll
hold off on a continued mention of the flooding threat in the HWO
beyond today for the time being. With there being less of a well-
defined focusing mechanism for development, it is difficult to pin
down a specific area that might be more favored for a flooding
threat. However, localized flooding will still be possible through
early next week, and if we're able to hone in on a particular area
that might have greater chances for heavy rainfall on a particular
day, additional mention in the HWO may be added at a later time.
/DL/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       86  73  87  73 /  68  35  66  32
Meridian      84  73  87  73 /  67  30  68  32
Vicksburg     86  73  88  73 /  62  40  63  32
Hattiesburg   87  74  88  73 /  66  26  69  29
Natchez       85  74  88  73 /  68  37  56  27
Greenville    86  72  86  73 /  42  32  59  27
Greenwood     86  72  86  73 /  63  47  59  36

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Flash Flood Watch until 7 PM CDT this evening for MSZ018-019-
     025>052.

LA...Flash Flood Watch until 7 PM CDT this evening for LAZ007>009-015-
     016.

AR...Flash Flood Watch until 7 PM CDT this evening for ARZ074-075.

&&

JPM3

Hazardous Weather Outlook
National Weather Service Jackson MS
257 PM CDT Wed Aug 9 2017

ARZ074-075-LAZ007>009-015-016-023>026-MSZ034-035-040>042-047-048-
053>056-059>066-072>074-102000-
Ashley-Chicot-Morehouse-West Carroll-East Carroll-Richland-
Madison LA-Franklin LA-Catahoula-Tensas-Concordia-Washington-
Humphreys-Issaquena-Sharkey-Yazoo-Warren-Hinds-Claiborne-Copiah-
Simpson-Smith-Jefferson-Adams-Franklin MS-Lincoln-Lawrence-
Jefferson Davis-Covington-Jones-Marion-Lamar-Forrest-
257 PM CDT Wed Aug 9 2017

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

.DAY ONE...Tonight and Thursday

FLOODING
THREAT...Elevated
TIMING...Mainly Thursday

Flash Flooding is expected over portions of the region on
Thursday. Thunderstorms capable of 1 to 2 inches of rain in a short
amount of time will move across the same areas that have
received several inches of rain over the past several days.

(www.weather.gov/images/jan/graphicast/image2.png)

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

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 Tuesday.

MSZ018-019-025>033-036>039-043>046-049>052-057-058-102000-
Bolivar-Sunflower-Leflore-Grenada-Carroll-Montgomery-Webster-Clay-
Lowndes-Choctaw-Oktibbeha-Holmes-Attala-Winston-Noxubee-
Madison MS-Leake-Neshoba-Kemper-Rankin-Scott-Newton-Lauderdale-
Jasper-Clarke-
257 PM CDT Wed Aug 9 2017

This hazardous weather outlook is for portions of central
Mississippi, east central Mississippi, and north central
Mississippi.

.DAY ONE...Tonight and Thursday

FLOODING
THREAT...Limited
TIMING...Tonight through Thursday

Flash Flooding is possible over portions of the area tonight
through Thursday. Thunderstorms capable of 1 to 2 inches of rain
in a short amount of time will move across the same areas that
have received several inches of rain over the past several days.

(www.weather.gov/images/jan/graphicast/image*.png)

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

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 Tuesday.

3

&&

...HAZARD LEGEND...

*FLOODING*
Extreme...Confident in significant flooding.
Significant...Significant flooding possible.
Elevated...Confident in flooding.
Limited...Flooding possible.

...USEFUL WEATHER WEB PAGES (URLS)...

NWS JAN Home page...
   www.weather.gov/jan
Stay Aware, Stay Safe NWS JAN Briefing Page...
   www.weather.gov/jan/safe
Latest Weather Briefing...
   www.weather.gov/jan/weather_briefing

Tropical page...
   www.weather.gov/jan/tropical
National Hurricane Center Home Page...
   www.nhc.noaa.gov/
Find NWS JAN on Facebook...
   www.facebook.com/NWSJacksonMS
Follow NWS JAN on Twitter...
   @NWSJacksonMS
Follow NWS JAN on Youtube...
   www.youtube.com/user/NWSJacksonMiss

...ADDITIONAL URLS FOR FLOODING ISSUES...

Current Watches and Warnings...
   www.weather.gov/jan/safe_HeavyRain

Observed Precipitation Images...
   www.weather.gov/jan/precipmaps

River Forecast Center...
   www.weather.gov/lmrfc/
Significant River Flood Outlook...
   www.wpc.ncep.noaa.gov/nationalfloodoutlook/index.html
Day 1 through 3 Excessive Rainfall...
   www.wpc.ncep.noaa.gov/qpf/excess_rain.shtml
Excessive Rainfall Discussion...
   www.wpc.ncep.noaa.gov/discussions/qpferd.html
Day 1 through 7 QPF...
   www.wpc.ncep.noaa.gov/qpf/qpf2.shtml
QPF Discussion...
   www.wpc.ncep.noaa.gov/discussions/qpfpfd.html

Special Weather Statement
National Weather Service Jackson MS
318 PM CDT WED AUG 9 2017

MSZ052-092100-
Lauderdale MS-
318 PM CDT WED AUG 9 2017

...A STRONG THUNDERSTORM WILL AFFECT LAUDERDALE COUNTY UNTIL 400 PM
CDT...

At 318 PM CDT, Meteorologists were tracking a strong thunderstorm
over Zero, or near Meridian, moving northeast at 10 mph.

Winds in excess of 40 mph will be possible with this storm.

This strong thunderstorm will be near...
  Increase around 330 PM CDT.
  Marion around 345 PM CDT.
  Toomsuba, Alamucha and Kewanee around 400 PM CDT.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

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 3223 8843 3223 8862 3237 8888 3258 8844
      3258 8839
TIME...MOT...LOC 2018Z 237DEG 9KT 3233 8865

TW