Special Weather Statement, NWS Jackson, MS

Area Forecast Discussion
National Weather Service Jackson MS
Issued by National Weather Service Shreveport LA
1256 PM CDT Thu Jul 22 2021

.UPDATE...
Updated for 18Z aviation discussion

&&

.AVIATION...
18Z TAF discussion:
VFR conditions are prevailing at all sites this afternoon as cu
field continues to lift and expand across our terminal airspace.
Spotty convection is noted generally along and north of our I-20
terminals, and this trend should continue through the remainder of
this afternoon. Coverage is such that VCSH/VCTS has been included
with possible amendments needed if storms threaten any given site.
Otherwise, we should lose the cu field with the daytime heating
loss this evening with some convective debris mid and high clouds
lingering overnight. Some patchy fog could develop at a few sites
around daybreak, most notably at KGLH with brief impacts possible.
Cu field will return late in the period on Fri morning as heating
commences with ample low level moisture still in place. Sfc winds
will remain light and mostly variable, generally around 5 kts or
less and trending W/SW through the daytime hours.

&&

.DISCUSSION...
Cu field has developed quite rapidly this morning across much of
the region, and temperatures are trending just a bit warmer than
earlier anticipated. Therefore, hourly temperatures have been
adjusted slightly upward through the remainder of today and highs
accordingly, with the majority of the CWA expected to see lower
90s later this afternoon. As far as convection is concerned, do
anticipate an increase in shwrs and tstms through peak afternoon
heating with a remnant frontal boundary continuing to lift north
of I-20. This boundary will likely aid in convective development
so higher pops have been maintained generally along and north of
the I-20 corridor. Otherwise, no additional forecast updates are
needed at this time.

Prior discussion below:

Today and Tonight ...

With light to calm winds and significant surface moisture due to wet
ground and a very humid boundary layer, some fog has been reported
this morning and patchy fog will likely continue until an hour or
two after sunrise. With the initiation of daytime heating, the
boundary layer will become well mixed under mostly clear skies.
The moisture is seasonably deep and so limited availability of
lower moisture content air aloft exists for significant mixing out
of moisture today. This will allow heat indices to climb with
apparent temperatures likely top out in the upper 90s F for most
with a noticeable warming trend continuing compared to days
previous. Near to just above average upper heights will allow for
afternoon and evening isolated to scattered showers and storms.
MLCAPE should remain <2,500 j/kg and lapse rates are near moist
adiabatic which should limit the threat for wet microbursts. The
07/22 00z JAN RAOB measured 1.7" PWAT and comparing to model
guidance this may rise a bit today. An anomalous dry layer around
500 mb was sampled by the RAOB and is depicted both in water vapor
satellite imagery as well as forecast guidance. This dry region
will likely be transient and PWATS of 1.8-2.0" are likely a more
representative range. That being the case, efficient rainfall
production from any slow moving thunderstorm may pose an isolated
risk for ponding or flash flooding, particularly in urban or poor
drainage areas. Storms diminish overnight with only a few isolated
showers remaining by midnight. Highs today should top out near 90
F with lows tonight in the middle 70s F. /86/

Friday through mid-week...

While the main story last week was rain and flooding, we have now
flipped a switch in our weather pattern and should see the opposite.
The region will remain under ridging aloft through the forecast
period and this will limit convection to some degree. Coverage
should be more isolated to scattered in nature and convection will
become much more diurnal in nature than we had been seeing. The
upper ridge from the west will build in more through the weekend
into next week and this will mean the heat will also return. High
temperatures will reach the 90s across the region, with potential
for mid 90s in the west(I suppose the upper 90s aren't out of the
question either depending on how much the ridge builds east). High
atmospheric moisture will stick around, with dewpoints in the 70s
expected to continue. Because of this, heat indices will flirt with
the 100 to 105 degree range through much of the forecast period. We
will need to watch trends to see if heat indices will be higher and
any heat advisories or limited risk heat stress graphics will need
to be issued. /28/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       92  74  91  74 /  37  13  48  22
Meridian      91  72  91  72 /  38  17  57  14
Vicksburg     92  75  92  76 /  29  11  33  15
Hattiesburg   93  75  92  75 /  24   9  49  20
Natchez       91  74  91  74 /  23   8  29  11
Greenville    90  74  91  74 /  40  11  34  13
Greenwood     92  74  91  74 /  41   9  48  14

&&

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

&&

SHV

Hazardous Weather Outlook
National Weather Service Jackson MS
Issued by National Weather Service Shreveport LA
219 PM CDT Thu Jul 22 2021

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>027-034>036-
040>043-047>049-053>056-059>066-072>074-231930-
Ashley-Chicot-Morehouse-West Carroll-East Carroll-Richland-
Madison LA-Franklin LA-Catahoula-Tensas-Concordia-Bolivar-
Sunflower-Leflore-Grenada-Carroll-Washington-Humphreys-Holmes-
Issaquena-Sharkey-Yazoo-Madison MS-Warren-Hinds-Rankin-Claiborne-
Copiah-Simpson-Smith-Jefferson-Adams-Franklin MS-Lincoln-Lawrence-
Jefferson Davis-Covington-Jones-Marion-Lamar-Forrest-
219 PM CDT Thu Jul 22 2021

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

.DAY ONE...Tonight and Friday

EXCESSIVE HEAT
THREAT...Limited
TIMING...Friday

Temperatures in the lower to mid 90s combined higher dew points
will lead to heat indices in the 100 to 105 range for portions of
the area on Friday.

.DAYS TWO THROUGH SEVEN...Friday night through Wednesday

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 Wednesday.

MSZ028>033-037>039-044>046-050>052-057-058-231930-
Montgomery-Webster-Clay-Lowndes-Choctaw-Oktibbeha-Attala-Winston-
Noxubee-Leake-Neshoba-Kemper-Scott-Newton-Lauderdale-Jasper-
Clarke-
219 PM CDT Thu Jul 22 2021

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

.DAY ONE...Tonight and Friday

The probability for widespread hazardous weather is low.

.DAYS TWO THROUGH SEVEN...Friday night through Wednesday

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 Wednesday.

20

&&

...HAZARD LEGEND...

*EXCESSIVE HEAT*
Extreme...Maximum heat index greater than 110 degrees for 3 or
 more days in a row and/or air temperatures greater than 107
 degrees.
Significant...Maximum heat index greater than 110 degrees
 and/or air temperatures greater than 105 degrees.
Elevated...Maximum heat index 105 to 110 degrees and/or air
 temperatures greater than 103 degrees.
Limited...Maximum heat index near 105 degrees and/or air
 temperatures 100 to 103 degrees.

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

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

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

Special Weather Statement
National Weather Service Jackson MS
Issued by National Weather Service Shreveport LA
228 PM CDT Thu Jul 22 2021

MSZ049-050-222000-
Scott MS-Rankin MS-
228 PM CDT Thu Jul 22 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN RANKIN AND
SOUTHWESTERN SCOTT COUNTIES UNTIL 300 PM CDT...

At 228 PM CDT, Meteorologists were tracking a strong thunderstorm
over Fannin, or near Brandon, moving east at 20 mph.

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

This strong thunderstorm will be near...
  Goshen Springs around 235 PM CDT.
  Pisgah around 245 PM CDT.
  Pelahatchie and Leesburg around 300 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.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3222 8972 3222 8973 3219 8973 3229 9006
      3244 9004 3247 9002 3251 8971
TIME...MOT...LOC 1928Z 275DEG 15KT 3238 8997

33