Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus64 kjan 262107 

Area forecast discussion
National Weather Service Jackson MS
407 PM CDT sun Mar 26 2017

tonight and monday:

WV imagery this afternoon showing impressive cold core system
moving into the Central Plains with warm advection ascent taking
shape over TX/OK. Meanwhile in our neck of the Woods, much of the
cloud cover from this morning has mixed away as dewpoints have
fallen into the 50s. Better dewpoints are poised over southern
sections to advance northward over the area again tonight. As this
occurs, fog and low clouds will spread in from the south mainly
after midnight.

The hrrr is indicating that currently developing mesoscale convective system over OK will
grow eastward overnight into AR, but diminish toward sunrise over
eastern Arkansas as it moves into a more capped environment. Some concern
exists for its outflow to help force new convection over northern MS
in the morning, but models soundings continue to show impressive
capping that does not look to weaken until the afternoon. A less
impressive cap will exist over the northeast and it is in this area
that convection may initiate by afternoon. While a damaging wind
threat will exist with the storms, environmental parameters suggest
that large hail will be the primary threat. Cells look to be
scattered in nature during the afternoon and early evening until the
surface cold front moves in later in the evening. South of i20, the
cap strength looks to remain strong enough to only allow for
isolated convection, but severe potential will exist with these
storms as well. The convection will diminish toward late evening
with the loss of daytime heating./26/

Monday night through the week...

As the system that should bring US some potential severe weather
departs to the northeast Monday night, it will leave a cold front
draped across the north central portions of the arklamiss region.
Some light showers may linger along or near this front Monday night
but the remainder of the region will begin to dry out. Upper ridging
will move overhead for Tuesday, but as daytime heating occurs,
additional showers/storms may develop around this stalled front.

The upper ridge will push east through Tuesday night and into
Wednesday but will still have some hold on our area Wednesday. This
will keep conditions warm but mostly dry. The aforementioned stalled
front will move north as a warm front during the day on Wednesday,
which could ignite some warm advection showers across my far
northern counties(or develop completely north of my cwa). Our next
weather system will continue to develop out to our west. By
Wednesday evening, a 998mb surface low will be located across the
rolling plains of Texas as the upper trough/closed low will be
located slightly further north across the Texas Panhandle. A dryline
feature will be across the eastern pineywoods of Texas with storms
along/ahead of this feature in western Louisiana. Across our area, a
rather moist and unstable airmass will be in place with dewpoints in
the lower to mid 60s and temperatures having reached the lower to
mid 80s during the afternoon. During the evening hours, as the
surface low tracks to the north and east and the upper trough starts
to swing east, this line of storms should enter my western
counties/parishes and continue to track east overnight. Our
atmosphere will be rather unstable with steep lapse rates (vertical
totals of 28-31c and 7-8c/km mid level lapse rates) and greater deep
layer shear than we saw in previous events (40-45kts 0-6km shear)
and helicities are depicted as being 200-400 m2/s2. All of this
suggests that all hazards will be possible. Conditions look just as
good on Thursday, especially if the overnight line doesn't work over
the atmosphere. Looks like there could be several rounds of weather
with this event from Wednesday night through Thursday. In addition,
with precipitable water values around 1.5-1.7 inches, there could be some locally
heavy rainfall which perhaps could lead to some isolated flooding
instances given recent rainy conditions. Will continue with the
slight risk as highlighted by the previous shift, but expect that
this will be increased as the event gets closer and more details are
ironed out.

As the system pulls off to the northeast by Thursday evening/night,
rain will move out of the area and upper ridging will again move in
for the early part of the weekend. Springlike temperatures will
continue through the period with highs in the 70s and 80s and lows
in the 50s and 60s. /28/


18z taf discussion:
VFR conditions this afternoon and evening will give way to increasing
fog and low clouds with MVFR conditions by 27/06z. These
conditions along with periodic drops to IFR can be expected
overnight with conditions improving slightly after 27/13z./26/


Preliminary point temps/pops...
Jackson 63 83 63 81 / 8 39 37 29
Meridian 62 82 63 81 / 8 42 35 30
Vicksburg 64 83 64 81 / 9 37 35 28
Hattiesburg 64 82 64 82 / 7 34 21 27
Natchez 65 82 66 82 / 10 37 26 27
Greenville 62 79 59 76 / 16 42 36 19
Greenwood 62 81 61 77 / 14 55 58 25


Jan watches/warnings/advisories...


National Weather Service Glossary of Abbreviations