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Area forecast discussion 
National Weather Service Jackson MS
905 PM CDT Tuesday Apr 21 2015

Update...a few very light rainshowers are moving across the I-20
corridor this arklamiss this evening with partly to mostly cloudy
skies prevailing elsewhere. These light showers are diminishing and
expect a quiet night across the area with lows in the low 50s. The
current forecast is on track and no updates are needed at this
time./15/

Discussion...the tranquil weather of yesterday and today will be
coming to an end by Wednesday afternoon. Presently...high
pressure...centered over central MS...remains in control at the
surface. It has been sliding to the east today and this will continue
allowing winds to become southerly over the County Warning Area.

WV imagery showing a weak shortwave embedded in the middle level zonal
flow over the arklatex being aided by proximity of right entrance
region of 100+ knot 300 mb jet. An area of light showers has
developed as a result of the ascent with this wave over S Arkansas/north la.
Not much of this is making it to the ground...though...with very dry
air in the lower levels and dewpoints in the 30s/40s.

Low level southerly flow will get better underway late tonight into
Wednesday morning allowing the old frontal boundary to begin backing
up and middle 60 dewpoints into central la by 18z Wednesday. Above this
shallow moist layer...capping inversion looks to remain strong until
flow over the warm front can overcome it by late afternoon/evening.
Scattered convection is expected to develop along the boundary and
become quite robust. Middle/upper 20s vertical totals extend over the
region...so whatever surface based storms that get going near the
boundary will be able to maintain themselves in elevated fashion
to the east over the stable layer. With 60 knots of deep layer
shear...rotating updrafts are sure to be prevalent. Expect the full
gamut of severe weather to be in play near the boundary including a
few tornadoes. To the north and east of the boundary...large hail
will be a threat...as well as...damaging winds as stable layer does
not appear very deep.

The convection looks to diminish Thursday/Thursday night as
shortwave ridging moves over. But another...possibly more potent
severe potential will exist for Friday afternoon/night. With
increased upper support...low level wind field will get a healthy
boost...especially as 150 knot 300 mb jet approaches the arklatex by
late Friday afternoon. The surge in the wind field will allow lower
70s dewpoints to pool along the boundary from central MS to southern
Arkansas. Instability will be quite impressive as vertical totals near 30
will be the rule. 250-350 m2/s2 of 0-3km helicity will be available
in close proximity to the boundary with the majority of this in the
0-1km layer. At present we have limited over the area in the severe weather potential statement for
Friday. If these trends continue in the models...upward adjustment in
categories may be prudent./26/



&&

Aviation...some middle to high clouds were noted on satellite imagery
streaming over the County Warning Area as VFR conditions were being observed at all
taf sites at middle afternoon. VFR conditions are expected to prevail
through this evening as high pressure shifts east across the area
today. Light and variable winds will result. Models suggest some
MVFR/IFR visibility restrictions in the south Wednesday morning...which
will lift by 14z. /17/



&&

Preliminary point temps/pops...
Jackson 53 81 62 79 / 15 28 49 33
Meridian 51 81 62 77 / 15 12 48 31
Vicksburg 54 81 64 79 / 15 45 64 32
Hattiesburg 54 84 64 82 / 3 23 37 41
Natchez 55 82 65 82 / 5 52 63 36
Greenville 54 78 60 73 / 15 41 50 29
Greenwood 52 78 59 73 / 4 36 45 29

&&

Jan watches/warnings/advisories...
MS...none.
La...none.
Arkansas...none.
&&

$$

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