Area forecast discussion
National Weather Service Jackson MS
305 PM CDT Monday may 20 2013
Short term...tonight through Wednesday night...
the primary concerns will be potential for strong to severe storms
for Tuesday afternoon through Wednesday afternoon across the region. The
concern for locally heavy rainfall as well as probability of precipitation and temperatures.
Latest satellite imagery showed the region to be on the influence of
an upper ridge...centered over North Carolina. A broad upper trough with an
associated upper low was observed from the central and northern plains
with the axis extending to The Four Corners region.
Regionally...stratocu streaks was across the region which showed the
low level southerly flow across the arklamiss. On the surface high
pressure centered over Georgia and a cold front with the associated
storm system was noted from Kansas through West Texas...where it was
associated with a dry line. This combination was bringing in surface
southerly flow over the region. Readings across the region were
pushing into the upper 80s to around 90 as we get back to our Summer
like regime.
Tonight...regional cross sections and soundings shows another round
of stratus coming into the region. There will once again be enough low
level flow to hinder significant fog development...despite some
model forecasts. Some of the National WRF models shows some isolated convection
coming into the extreme northwest Delta Region after midnight. So adjusted
mav probability of precipitation slightly upward to account for it. Lows overnight were
generally from the 68-71 range. So will go with the generally the
same numbers as was noted with the milder raw GFS guidance.
Tuesday through Wednesday night...the plain upper trough axis moves
through the Southern Plains into the lower Mississippi Valley
through the period. The local and National WRF models shows some decent
strong to severe thunderstorm development for Tuesday afternoon
through Wednesday afternoon. The National WRF models shows a cold pooling
large complex bowing into the region from late Tuesday afternoon
into Tuesday night. By the looks of the reflectivity there could be
some gusty winds with this complex as it blows through the region.
Precipitable waters will be around 1.8 inches which also spells the risk of
locally heavy rainfall. Instability will be pretty good with
vertical totals around 30, MLCAPES >3000, lapse rates around 7-8c.
In the northwest Delta Region bulk shear 30-40 knots at 0-6 km with
near 200 helicity. So the best forcing looks to be in the northwest
Delta for a risk of a few tornadoes. Otherwise the primary risk will
be damaging winds and quarter sized hail. Our chances of severe
weather will continue through Wednesday afternoon across the entire
area. The best bulk shear and helicity will continue across the
northwest Delta Region. The risk of severe weather should decrease
for Wednesday night. The associated cold front will remain northwest
of the region through the period.
As far as temperatures are concern went close to the milder GFS guidance
for Tuesday night with lows from the upper 60s to lower 70s. Highs
on Tuesday will be from the upper 80s to around 90. Went close to
mav guidance. Highs for Wednesday will be from the lower to middle
80s. Went close to mav guidance. Lows for Wednesday night will be
slightly cooler with lows from the middle 60s to around 70. Went close
to mav guidance. For probability of precipitation went close to mav guidance./17/
Long term...Thursday through Monday...a weak frontal boundary will
continue to move across the arklamiss on Thursday. Isolated to
scattered showers and thunderstorms will continue to be
possible...especially Thursday afternoon. As the upper trough
continues to shift east of the area a stronger backdoor cold front
will drop south across the area early on Friday and this may kick
off some isolated thunderstorm activity once again Friday afternoon
before much drier air builds in from the northeast Friday night into
Saturday.
The weekend looks mainly dry on Saturday and Sunday as high pressure
ridging builds in from a surface high over the Ohio Valley and precipitable waters
fall well be low an inch. The drier air will result in lower rh's on
Saturday...but will still be very warm with highs up into the middle
80s. The surface high will shift east and this will allow the winds
to become more easterly than southeasterly...but high pressure
ridging and mainly dry conditions looks like it will continue
through Monday./15/17
&&
Aviation...VFR scattered-broken decks will continue this afternoon...giving
way to scattered VFR this evening at most locations. Conditions will
deteriorate after 08z with MVFR/IFR cigs/vsbys...locally LIFR...
redeveloping in low stratus and patchy fog...the better chance for
IFR/lift fog expected south of I-20 tonight. Conditions will
gradually improve after sunrise with areas of MVFR broken-overcast decks in
place by 16z improving to 3-5k feet broken-overcast by 18z. Isolated
showers/thunderstorms will be possible over northwestern zones during the afternoon
Tuesday with a slight chance of severe storms with large hail and 60
miles per hour wind gusts.
&&
Preliminary point temps/pops...
Jackson 68 89 69 83 / 10 19 29 40
Meridian 68 91 64 85 / 9 12 15 30
Vicksburg 71 89 69 85 / 10 24 42 37
Hattiesburg 68 91 67 85 / 7 10 13 28
Natchez 71 88 70 84 / 7 16 25 41
Greenville 71 89 70 87 / 15 39 61 35
Greenwood 69 90 69 85 / 13 32 49 37
&&
Jan watches/warnings/advisories...
MS...none.
La...none.
Arkansas...none.
&&
$$
17/22/15
