Area Forecast Discussion
Issued by NWS Jackson, MS

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS64 KJAN 161601 AAA

Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
1001 AM CST Sat Dec 16 2017

Updated for morning discussion.


After a chilly start this morning temperatures were warming as
expected. The surface high centered over our area early this
morning has shifted east and a light return flow is expected
today. Temperatures will top out close to normal this afternoon.
The main change with this update was to increase cloud cover
across our southern zones as a band of mid level clouds was
thicker than anticipated. This band will spread north and thin
this afternoon. /22/

Prior discussion below:

Today through tonight: A chilly polar airmass is entrenched over
the ArkLaMiss region as of early this morning with temperatures
falling well into the 20s over most of the forecast area. This
airmass will be slow to modify this morning, but the slow moving
cut-off low crossing northern Mexico will eject quickly eastward
toward our region as a major upstream trough digs southward
through the western CONUS. The rapid approach of the low will
cause rapid mass northward transport of anomalously moist air for
mid December (precipitable water > 1.5 inches, ~3 SDs) into the
area. Expect showers and perhaps a few elevated thunderstorms to
develop rapidly and move into western portions of the area prior
to daybreak Sunday, but not expecting too many run-off problems
given the antecedent drought conditions and progressive nature of
initial activity. This could be a different story looking down the
road. Otherwise, expect a much milder Saturday night for most of
the ArkLaMiss given the modifying airmass and increasing cloud
cover. /EC/

Sunday through the work week: Confidence is increasing in a
dynamic, wet pattern unfolding from Sunday through next weekend as
models come into better agreement.

Rain will continue to spread into the region on Sunday as a
deamplifying upper level shortwave trough embedded in SW flow
progresses over the area. Significant lift and bountiful moisture,
by the way of Pwats of 1.5"-1.8", will result in heavy rainfall at
times. However, as mentioned previously, both the progressive
nature of this system and recent dry conditions will help lessen
the flash flood threat. Even though the best instability will
remain offshore over the northern Gulf, sufficient bulk shear
magnitudes in the ranges of 45-50kts between 0-3km and 50-60kts
between 0-6km indicate that there could be some strong storms
mainly in the Pinebelt region on Sunday.

The upper level SW flow regime will remain intact through early
week while flow from the south in the mid to low levels will
continue to supply the region with ample moisture from the Gulf.
This will result in rain chances sticking around through Monday
and Tuesday. A deep cutoff low will begin to cross the Southern
Plains as the week progresses, approaching the lower MS Valley
region by Wednesday. A very moist atmosphere will exist ahead of
this system as it brings some significant height falls to the
region. There are still some differences spatially and temporally
between the GFS and Euro, but our best chance for organized storms
during the week will exist as the aforementioned disturbance
traverses the region Tuesday night through Wednesday.

The sun may finally make an appearance later in the afternoon on
Wednesday or early Thursday as dry air finally filters into the
region behind this disturbance and some weak ridging builds into
the upper levels. However, this quiet period will be short lived
as rain chances begin to increase once again as the upper level
pattern transitions back to a SW flow regime in response to a deep
trough splitting off from the mean flow and diving towards the SW
US/Mexican border. /JPM3/


12Z TAF discussion:
VFR conditions and mostly light and variable wind will prevail
through this evening. Expect lowering ceilings and increasing SHRA
chances prior to daybreak Sunday morning in the GLH/GWO/JAN/HKS/
HBG area. /EC/


Jackson       60  44  66  55 /   1  45  84  34
Meridian      57  42  63  54 /   1  10  82  41
Vicksburg     60  44  66  52 /   1  79  83  20
Hattiesburg   57  43  70  60 /   1  11  83  45
Natchez       59  46  69  57 /   3  74  84  37
Greenville    59  43  62  48 /   0  90  79  15
Greenwood     60  41  62  48 /   0  76  84  18





JPM3/22/EC is the U.S. government's official web portal to all federal, state and local government web resources and services.