Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 210326
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
926 PM CST Wed Feb 20 2019

.UPDATE...
Updated for evening discussion.

&&

.DISCUSSION...
Active weather will continue tonight into tomorrow morning as a
frontal boundary continues to drift back and forth across the
region beneath sustained moist southwesterly flow aloft. The
frontal boundary pushed through much of the area today and is
currently analyzed over southeast Mississippi where it has
stalled. The boundary is progged to lift back north overnight with
increasing isentropic ascent and strong baroclinicity supporting
another round of showers and thunderstorms. This band of
convection will slowly lift northwest overnight into tomorrow
morning with the slowest movement over southeast Mississippi
generally along and southeast of the Natchez Trace. It is over
this area where training convection could result in additional
flooding issues, especially for locations that already observed heavy
rainfall and flash flooding earlier today, as 1-2" of rain with
locally higher amounts is expected. This convection will reside in
an environment supportive of enhanced rainfall rates owing to
upwards of 500 J/kg of MUCAPE, 1.5" PWATs, respectable deep
moisture convergence and H850 dewpoints of 11-13 C. The main focus
for the forecast update was to adjust PoPs accordingly in addition
to expanding the limited flood threat in the HWO/graphics to
include the Jackson metro. Latest suite of hi-res CAM guidance is
in agreement on a swath of 1-2" with locally higher amounts
across the limited threat area, however uncertainty exists with
regards to the exact placement of these totals. Flooding issues
could be exacerbated if these locally higher amounts are realized
within the same axis from Brookhaven to Mendenhall to Forest that
observed widespread flooding today. /TW/

Prior discussion below:

Tonight through Thursday...The showers and storms have cleared
from most of the area this afternoon but this will be short lived.
The frontal boundary will be stalled over the Pine Belt region this
evening, but as another short wave approaches the area overnight the
front will begin to move back to the northwest. As the boundary
moves back to the north, showers and thunderstorms will be on the
increase once again early on Thursday. These storms will push
northward through the morning into the afternoon hours. Due to the
already saturated soils, will issue a limited risk for flooding over
the southern and eastern portions of the area where heavy rainfall
fell earlier today. These areas could see another 1-2 inches
Thursday morning through the afternoon hours. With the storms being
elevated and also limited instability on Thursday, expect the storms
to remain sub-severe, but a strong storm or two cannot be ruled out.
/15/

Thursday night through early next week...

Expect showers/storms to become widespread by Thursday night with
the flash flood threat rapidly increasing over the Delta region
into NC MS by that time, in areas that can not hold much if any
additional rainfall. Will be issuing a flash flood watch for this
area and upping the hazardous weather outlook/graphic threat to
significant as well for the Thu aftn through Saturday night time
frame to account for what will likely be a significant flooding
event. Farther southeast, QPF is less on average and rainfall
hasn`t been quite as heavy, but cannot rule out some localized FF
issues at any locations given the continued strong moisture
transport in areas that manage to develop. Otherwise, the severe
threat for late week into the weekend has not changed much. /EC/

By the daytime on Friday, low-level humidity and increasingly
warm temperatures will become more supportive of isolated strong
to severe thunderstorms developing south of the front. This
activity will be driven by daytime heating, and some capping may
limit overall coverage of thunderstorm development. Therefore a
Marginal risk for severe thunderstorms has been introduced to the
forecast for the day on Friday - for northeast Louisiana,
southeast Arkansas, and areas in Mississippi mainly along and west
of Interstate 55.

A separate round of severe thunderstorms is anticipated for Saturday
as the western CONUS trough swings across the country and lifts out
of the Plains during the day. Continued warm, moist advection ahead
of a deepening surface low  and stronger dynamics as a jet streak
rounds the base of the trough will bring a better chance for severe
thunderstorms to develop. Overall forcing will favor northern
portions of our forecast area, where the current Slight risk has
been expanded eastward to encompass all of northern and north-
central Mississippi for Saturday. A nice punch of dry air in the
wake of a cold front Saturday night will clear out rain chances
through at least Monday, and the upper-air pattern will become zonal
across the country. Rain chances start to creep back northward
Monday night into Tuesday as flow off the Gulf of Mexico returns. At
this time, there are no concerns for flooding rains or severe
weather early next week. /NF/

&&

.AVIATION...
00Z TAF discussion:
A mixture of flight categories is occurring this evening from VFR
to LIFR. This is due to low stratus and perhaps some light
drizzle/mist lingering across the area. This will continue through
the night. With the cold front stalled over the southeast, rain
and perhaps some thunderstorms will be possible overnight, lifting
north and affecting other TAF sites through the day tomorrow. This
will keep low ceilings and vis at all TAF sites with minimal
chance to return to VFR over the next 24 hours. /28/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       50  61  53  75 /  80  92  77  68
Meridian      53  64  54  76 /  92  59  63  64
Vicksburg     47  56  51  74 /  39  91  88  72
Hattiesburg   58  73  63  79 /  80  51  51  43
Natchez       50  60  54  76 /  83  88  73  68
Greenville    40  53  48  65 /   0  95  92  84
Greenwood     43  54  49  69 /   3  95  94  79

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Flash Flood Watch from Thursday afternoon through Saturday
     evening for MSZ018-019-025>042.

LA...Flash Flood Watch from Thursday afternoon through Saturday
     evening for LAZ007>009-015.

AR...Flash Flood Watch from Thursday afternoon through Saturday
     evening for ARZ074-075.


&&


$$

TW/NF/15/28/EC


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