Area forecast discussion...updated
National Weather Service Jackson MS
1102 am CDT Tuesday may 21 2013
Update...expect partly cloudy skies today with increasing chances
for shower and thunderstorm activity...especially across the
west...as we go into the afternoon. Temperatures late this morning
were in the lower 80s across most of the region...with afternoon
highs around 90 expected. As for the current forecast...increased
probability of precipitation across the western County Warning Area for this afternoon...and adjusted the
hourly temperatures to account for slightly quicker warming this morning.
&&
Aviation...other than scattered-broken 2-3kft decks through 17z...VFR
conditions can be expected across the area today. Isolated showers and
thunderstorms will be possible over the Delta Region with a slight chance of
severe storm development during the afternoon. Conditions will
deteriorate to MVFR ceilings...local IFR cigs/vsbys...from the northwest during
the evening as a weather disturbance approaches the region and
chances of showers and thunderstorms increase. Severe thunderstorms will be possible
with the potential for large hail and damaging winds along with a
few tornadoes. The risk for strong to severe storms with large hail
and damaging wind will extend across areas along and northwest of the
Natchez trace by sunrise Wednesday.
&&
Previous discussion... /issued 410 am CDT Tuesday may 21 2013/
Short term...today through Wednesday night...a weakening outflow
boundary from convection to our northwest will push a few showers and
thunderstorms into our northern most zones early this morning but
this activity should not become severe. The main threat for any
strong to severe thunderstorms will hold off until late this
afternoon and tonight...and mainly over the northwest half of the
area. Early morning water vapor imagery shows the circulation around
a nearly stacked low over the northern plains and a shortwave
rounding the base of the broad upper level trough...just west of the
Texas Panhandle. This shortwave will continue to swing east today and
across our County Warning Area Wednesday morning. In the meantime...weakened ridging
surface and aloft will continue to limit convection over the
southeast half of our area today and lead to warmer than normal
afternoon highs near 90f again. The warm temperatures combined with
dew point temperatures in the lower 70s will result in MLCAPES of
2000-2400j/kg in the west. This combined with middle level lapse rates
near 7... -4 to -6 and 0-6km bulk shear around 30kts
will support severe storm development this afternoon in our west.
Less favorable conditions will exist the father east you go in our
County Warning Area. The boundary stalling across the Delta this morning may help
initialize some storms. Otherwise...models agree that the main
forcing associated with shortwave trough will arrive in our northwest
until after midnight. Overall instability will be less with the loss
of daytime heating this evening...but low level flow will increase
with 0-1km and 0-3km srh of 150-200 m2/s2. Large hail...damaging
winds and a few tornadoes will be possible tonight. This potential
will be greatest in southeast Arkansas...northeast Louisiana and in
the far northwest Delta late this evening to early Wednesday morning.
The shortwave is expected to be east of our County Warning Area by Wednesday
afternoon. In its wake drier air and subsidence will spread over our
County Warning Area from the west. Conditions will be less favorable for severe
storms Wednesday but...a few strong storms will be hard to rule out
Wednesday afternoon in the southeast. /22/
Long term...Thursday through Tuesday...generally quiet conditions
will exist as upper ridging is situated over the MS River Valley. To
the east of that ridge axis will be a decent trough which will help
push a cool front into and possibly through the region. On
Thursday...there will likely be some sort of stalled boundary near
the County Warning Area...but a better push of cooler air will make a run at the
region thanks to the developing trough axis to our east. There are
some differences in just how far south the true cool/dry air will
get...so I used somewhat of a blend of the GFS/Euro with more of a
lean to the GFS. Overall...below average conditions look to exist for
the weekend (fri-sun) with moderating conditions for early next
week. The GFS keeps the region dry through this time...but by the
latter half of the weekend...a northwest flow regime will be in place and
while that often brings US the nice/pleasant weather...it can also
bring surprises this time of year in the form of shra/tsra. At this
time...will follow the GFS and keep the area dry/precipitation free. /Cme/
&&
Preliminary point temps/pops...
Jackson 90 68 85 65 / 15 53 57 16
Meridian 90 67 86 64 / 7 30 49 28
Vicksburg 89 70 86 62 / 28 69 59 9
Hattiesburg 90 67 87 66 / 6 17 44 23
Natchez 89 70 85 64 / 17 59 60 14
Greenville 89 71 86 62 / 47 87 44 6
Greenwood 89 69 86 63 / 37 74 51 8
&&
Jan watches/warnings/advisories...
MS...none.
La...none.
Arkansas...none.
&&
$$
