Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 262116
AFDJAN

Area Forecast Discussion
National Weather Service Jackson MS
316 PM CST Sun Feb 26 2017

......ACTIVE WEATHER EXPECTED THROUGH MID WEEK......

.DISCUSSION...
Now through the day tomorrow:

It has been another very dry (in terms of humidity) day across the
region with temperatures more pleasant than yesterday as the
overall trend to above average readings has kicked back in.
Despite southeast winds at the surface, moisture has yet to return
to the boundary layer and the combination of the somewhat gusty
winds and low relative humidity is again increasing fire weather
concerns. More on the specifics of the fire concerns is mentioned
in the dedicated section below. Fortunately, fire danger will not
be a concern anytime in the near future (after this afternoon)
since starting tonight the increasing southerly flow above the
surface will be bringing back moisture from the Gulf of Mexico
quickly.

A fast-moving upper level disturbance headed at the region tonight
will be the impetus for the rapid moisture return as the
disturbance effectively shoves the nearby surface high quickly off
to the east and strengthens return flow up the Lower Mississippi
Valley. Model consensus suggests the current rash of showers
breaking out to our west will consolidate and grow this evening
into a larger complex of showers and thunderstorms, which will
then translate east into western zones before dawn. After daybreak
this convection should continue to shift east through the heart
of the region, probably anchored at the nose of maximum warmth and
moisture advection a few thousand feet above the surface (which
basically should be along the I-20 corridor). Instability
overnight into mid morning tomorrow should be based above the
surface, greatly limiting the potential for severe weather (although
some small hail is still possible in this time window over
western zones). More worrisome will be mid morning through early
afternoon tomorrow as there will likely be an outflow boundary
laid down over southern zones by the main convection where non-
negligible surface-based instability could build and help trigger
some storms more capable of severe weather. The available suite of
high resolution guidance is not in high agreement concerning
convective evolution tomorrow, but we feel over central and zones
it is still worth mentioning the potential for at least one or two
storms getting up to severe potential.

By late in the afternoon tomorrow the main upper level short wave
will be shifting to the east and subsidence in its wake should be
shutting down the threat for deep convection. Many locations,
especially over east-central MS, will have struggled to warm much
before this time, but will likely get a chance to make a run up
toward 70 degrees before the afternoon is totally done. /BB/

Monday night through next week:

We will be looking at an active period with rain chances coming for
Monday night through Wednesday night with mild temperatures.
This will be followed by dry and cool weather for Thursday through
Saturday before some rain comes back in the south on Saturday night.
The best severe potential looks to be on Wednesday with the cold
front passage. There will be some limited severe potential for
Tuesday night in the northwest.

On Monday night convection will be increasing over the northern
counties in the vicinity of the warm front and the upper level jet.

On Tuesday a midlevel trough will be pushing toward the Plains. This
will push a cold front toward the Ozarks for Tuesday night. Surface
based Instability will be prevalent with lapse rates 7-8C,
increasing low level shear 35 knots and deep layer shear 60-70 knots
in the delta region, showalters -2 to -4,VT 28-30, and MUCapes
around 1800 j/kg. The main axis of the upper jet will be north of
the region. However we will have a good low level jet of around 40
to 50 knots. With warm heights over the region we will be rather
capped with the approach of the midlevel trough, which will affect
the convective coverage in the south half. The best chance of storms
will be in the northwest for Tuesday night with the approach of the
system. SPC has a marginal risk over our northwest delta with a
slight risk just to our northwest. With this in mind will keep a
limited severe graphic for the northwest delta region with the
approaching system for Tuesday night. The primary risks will be
damaging winds, and hail.

On Wednesday the midlevel trough will be pushing toward the region
from the Plains. This will send a cold front into the region. Ahead
of the cold front we will have low level shear 30-40 knots, deep
layer shear 60-70 knots, storm relative helicity of 200-300, VT 28-
30, and showalters -2 to -4. This will be enough for some tornado
potential across the region ahead of the cold front. SPC has put a
30 percent risk for our northern counties and a 15 percent risk
elsewhere. So with this in mind will keep the Elevated risk across
the north and limited risk across the central and south. So will
keep the primary risk being damaging winds, hail and a tornado can
not be ruled out. Conditions look to favor a squall line to develop
along the frontal boundary as it sweep across the region with some
damaging winds. The front will sweep across most of the region by
Wednesday night. Models were still having some timing issues with
the frontal passage. The rains will end from the northwest in the
wake of the front on Wednesday night. Cool High pressure will build
in from the plains on Thursday into Friday. On Saturday high
pressure will track east of the region which will bring back
southerly low level return flow. Pwats will increase from the west
to around one inch, which will help some isolated showers to develop
across the south on Saturday night.

As far as temperatures are concern we will be looking at a warming
trend as we push through the work week with highs peaking at the
upper 70s to the lower 80s on Tuesday. Lows will rise to the 60s by
Tuesday night. In the wake of the cold front highs will be in the
60s for Thursday through Saturday. Lows will dip into the 40s for
Wednesday night then 30s and 40s for Thursday night and Friday
night. Lows will recover into the 40s and 50s for Saturday night.

Looking into Sunday into early next week it looks like our rain
chances will spread across the region on Sunday into Monday. This
will be associated with an strong upper trough to the north which
will drag a cold front through for early next week./17/

&&

.AVIATION...
18Z TAF discussion:

VFR conditions are anticipated in all areas until late tonight
when MVFR cigs and showers and thunderstorms will begin moving in
from the first (arriving before daybreak at GLH/GWO. Other sites
will likely see impacts from daybreak through midday, although
some more isolated showers and storms and lingering MVFR cigs
could affect a few locales well into the afternoon hours tomorrow.
No big wind shifts are anticipated through tomorrow, aside from a
possible brief wind shift to the west late tonight through early
afternoon tomorrow when/if impacted by a band of
thunderstorms./BB/

&&

.FIRE WEATHER...
Fire danger will continue to be a concern through the remainder of
the afternoon as RH`s should range from 15 to 25 percent for a
good portion of our area. Winds will be moderate and from the
south, maxing out at near 10-12kts, but will be falling in the
next few hours. The fuel moisture content will be below 10% for
most of the region, but will also rise rather quickly early this
evening as well. Expect moistening of the atmosphere overnight and
tomorrow to alleviate fire concerns beyond today. /BB/

&&

.PRELIMINARY POINT TEMPS/POPS...
Jackson       52  72  63  81 /  43  78  23  20
Meridian      47  70  61  79 /  13  73  23  20
Vicksburg     54  74  64  82 /  53  79  25  23
Hattiesburg   49  75  63  81 /  10  66  16  12
Natchez       57  77  66  82 /  47  74  18  20
Greenville    50  68  62  78 /  88  70  45  34
Greenwood     49  67  61  80 /  75  83  44  33

&&

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

&&


$$

17/BB


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