Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 221749 AAB
AFDJAN

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1249 PM CDT Mon May 22 2017

.UPDATE...
Updated for 18Z aviation discussion

&&

.AVIATION...
18Z TAF discussion:
VFR ceilings at many of the northern TAF locations will slowly
lower through the afternoon and evening becoming MVFR by 23/06Z.
At MEI and HBG, MVFR conditions will prevail through the period.
Areas of rain and embedded thunderstorms will begin impacting the
TAF sites from the west by late afternoon and evening and continue
through most of the night./26/

&&

.DISCUSSION...
Clouds have thinned a bit this morning over the forecast area, but
that will not last long as expansive clooud cover over AR and LA
spreads east. Widespread rain and embedded thunderstorms continue
to develop this morning over TX/LA as flow around surface low over
southeast TX continues to push warm/moist air northward over the
more dense airmass north of the surface boundary. Still expect
rainfall to move into the area, but question marks exist as to
where the heaviest rain will occur. The expanse of rain to the
north of the boundary would suggest that the boundary will remain
locked in over far southern LA/MS. This would keep the heaviest
rainfall along and just to the north of the boundary which seems
what the latest model data is showing. Will keep FFA as is for the
moment, but if the remainder of the new forecast data shows
similar solutions, may begin clearing counties from the north by
noon./26/

Prior discussion below:

Today and Tonight:

The main focus for the next 24 hours will be the potential for
heavy rain. The next round of showers and thunderstorms will be
associated with a shortwave observed over eastern Texas/western
Louisiana early this morning. Ongoing showery activity can be seen
on regional radars. As the wave slides eastward, it will lift
moisture rich air from the Gulf of Mexico over a stalled frontal
boundary along the coast. PWAT values are near 1.5 inches across
our forecast area following yesterday evening`s round of rainfall,
but values closer to 2.0 inches along the coast will shift back
northwards today. The greatest threat for heavy rainfall and
possible flooding in our forecast area will be south of a line
from near Natchez, MS to Meridian, MS. Lift from the shortwave and
a combination of greater instability and moisture will be
concentrated through those areas. Lesser storm coverage and lower
moisture content to the north and west of these areas will lead
to a more Limited threat for flooding elsewhere across our
forecast area. Also any rain that falls will be on wetter ground
following recent rain, so runoff will be faster and flash flooding
more likely. A Flash Flood Watch will continue through around
Midnight tonight. An isolated stronger storm or two can`t be ruled
out either, with damaging wind gusts being the primary hazard.
The chance for rain will taper off after midnight, but showers and
a few storms could still be possible. /NF/

Tuesday through Sunday:

Troughing aloft across the Lower Mississippi River Valley, will
keep rain chances in the forecast through the middle of the work
week. Behind the passage of Monday night`s system, rain chances
look to overall remain on the low side during the Tuesday day
period as we sit between systems. Although a better chance of
showers and storms will be across my southeast zones closer to the
boundary.

Tuesday night however, as the closed low drops southeast into the
Mid-Mississippi River Valley, a sharper shortwave will rapidly swing
east from the Southern Plains and into the region.  This will result
in a surface low developing well north of our area and lifting north
northeast into the Great Lakes region.  As this happens, a cold
front will shift east into and through the forecast area Tuesday
night into Wednesday morning, bringing yet another good chance of
showers and storms to the forecast area.

Behind the front, due to the continued digging trough swinging
through the forecast area during the Wednesday day period, clouds
and rain chances will continue as said trough squeezes any remaining
moisture aloft out across the forecast area, especially north of the
Interstate 20 corridor. A slightly cooler drier airmass will also
advect into the forecast area through the day Wednesday.  Clouds
begin to lift off to the north overnight Wednesday, as rain chances
finally come to an end.

Behind the trough and front, ridging aloft and high pressure at the
surface will build into and through the region Thursday into Friday.
This will allow a drying period across the forecast area, but
conditions warm and moisten by Friday, and heading into the Memorial
Day weekend. Rain chances again increase as we progress through the
weekend, as yet another trough is progged to push a cold front into
and through region Sunday into Sunday night. /19/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       74  61  79  60 /  79  75  35  49
Meridian      77  61  79  62 /  71  88  47  50
Vicksburg     72  61  79  60 /  78  62  35  49
Hattiesburg   78  63  77  64 /  58  90  63  42
Natchez       72  62  78  60 /  76  74  41  38
Greenville    74  60  78  58 /  74  40  28  60
Greenwood     75  60  78  58 /  72  56  27  59

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Flash Flood Watch through late tonight for MSZ052-054>066-
     072>074.

LA...Flash Flood Watch through late tonight for LAZ024-026.

AR...None.

&&


$$



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