Area forecast discussion
National Weather Service Jackson MS
343 am CDT sun may 19 2013
Short term...tonight through Monday night...
satellite and observations indicate stratus building into the area
from the southeast this morning...while some high clouds also stream in from
upstream convection over the plains. Late Spring humidity is
prevalent with dewpoints in the upper 60s to near 70.
Expect areas of stratus to continue to overspread region early this
morning...and then gradually give way to a mix of sun...cumulus and
high clouds through the day. Northern periphery of an upper
disturbance currently along Upper Texas coast per water vapor is
expected to skirt across southern parts of forecast area this
afternoon. Capping is forecast by the models to hold today...but
some concern that combination of daytime heating and some vertical
motion associated with the wave could erode capping enough for an
isolated storm or two to develop in southern areas. Support for this in
the models is pretty slim though...with only Storm Prediction Center 4 km WRF showing any
development with other National/local high res and global models all
dry. For now will leave any mention of probability of precipitation out of forecast...but
will note that if by chance anything were to develop it could be
strong given model forecasts of steep lapse rates and MLCAPE values
near 3000 j/kg. Guidance temperatures look reasonable today.
Tonight and Monday night should pretty much be a repeat of this morning
with stratus increasing from the south and high level convective
debris likely increasing from the W/NW. Combination of clouds and
dewpoints in 65 to 70 degree range wouuld seem to support mins a few
degrees above GFS MOS.
Monday should be similar to today. Models show axis of highest precipitable water and
lowest cinh across western areas Monday afternoon. For now expect that
building heights and capping will win out even here...and will leave
probability of precipitation out of forecast. Guidance temperatures accepted. /08/
Long term...Tuesday through Sunday...by Tuesday morning the nearly
stacked low will be over the Central Plains with a shortwave
rounding its base over the Southern Plains. Shortwave ridging aloft
and surface ridging from the east will still be dominant across our
County Warning Area Tuesday morning but heights will be falling as the upper trough
draws closer. A rather warm and humid day is expected as
temperatures top out in the upper 80s. Along and west of the
Mississippi River precipitable waters are expected to exceed an inch and a half with
lower 70 degree surface dew points. Daytime heating should lead to
afternoon and evening convection in our western zones while
convection remains more inhibited east. With MLCAPES above
2000j/kg...7.5c/km middle level lapse rates and vertical totals
29-30...a few strong to severe hail producing storms will be
possible. Tuesday night into Wednesday the low will lift NE and
weaken over the upper Mississippi River valley. The weakening upper
level trough will swing across our County Warning Area Wednesday but models have
backed off on any frontal passage in our County Warning Area as the front fizzles north of our
area. Overall...thermodynamic parameters look less favorable for
severe weather Wednesday into Thursday but will still have a warm moist
airmass in place with rather steep middle level lapse rates so a few
strong storms will be hard to rule out. The upper trough axis will be
east of our County Warning Area Thursday but northwest flow aloft will continue over
our County Warning Area through Saturday. Although most of the convection will should
show a distinct diurnal trend...models indicate disturbances aloft in
the northwest flow may set off some convection over night Thursday and
Friday nights. In addition...both GFS and European model (ecmwf) show a surface high
dropping over the Great Lakes region Friday night that may push a
weak backdoor cold front into our County Warning Area Saturday. Ridging surface and
aloft is expected to build over our region Sunday resulting in dry
weather. /22/
&&
Aviation...
low level flow appears to be strong enough this morning to favor
stratus over fog...with expectation that IFR ceilings will be prevalent
most areas by 12z. Thinking is that lowest visibility will occur at kgtr
where heavy rain fell Friday/Friday night and winds should be
lightest...may see some IFR visibility here. Elsewhere expect no worse
than MVFR visibilities in br through 14z. Stratus/br should gradually mix
out/burn off through the morning...with a mix of cumulus at 030-040
and some cirrus exected by afternoon. Winds will be from the south
and gusty at times...particularly in the Delta as 25-35 knots 925 mb
flow mixes out. Generally expect a repeat as far as stratus
development for tonight as we are seeing this morning. /08/
&&
Preliminary point temps/pops...
Jackson 89 70 89 70 / 4 5 8 9
Meridian 88 68 90 66 / 6 5 7 8
Vicksburg 89 70 90 70 / 5 5 9 10
Hattiesburg 88 70 89 68 / 5 5 9 6
Natchez 89 71 88 70 / 5 5 10 7
Greenville 90 71 89 70 / 6 5 9 11
Greenwood 89 70 89 69 / 6 5 9 10
&&
Jan watches/warnings/advisories...
MS...none.
La...none.
Arkansas...none.
&&
$$
08/22
