Scientific Forecaster Discussion

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Area forecast discussion...updated 
National Weather Service Jackson MS
826 PM CDT Thursday Apr 17 2014

Update...main forecast adjustments were to this evenings weather as
precipitation is having a hard time developing or making into the County Warning Area. Due
to this probability of precipitation/weather were lowered and pushed back in time. After
midnight...increasing deep lift and moisture transport from our southeast
looks to support a rain shield skirting the County Warning Area and bringing at
least some light measurable precipitation to the southeast part of the County Warning Area. I want
to add that their remains the possibility that the large convective
complex over the central Gulf could keep moisture cut off. If this
occurs...then getting any precipitation anywhere later tonight may be a
real challenge. Overall...precipitation chances were lowered a bit for
central...W/NW/N locations. Hourly temperatures were modified quite a bit
this evening as a slower temperature fall is occurring due to clouds/wind.
Overnight lows are still generally on track. /Cme/


Aviation...VFR conditions exist across the region this evening but
overcast ceilings are present with heights >5 or 10kft. Look for ceilings
to lower as we approach midnight...first across the southeast and east-central
areas then spreading across all of the County Warning Area through sunrise. Precipitation
will be limited for this evening...but a more expansive shield of
-ra is expected across the southeast areas later. Look for improving
conditions between 16-19z Friday. /Cme/


Previous discussion... /issued 344 PM CDT Thursday Apr 17 2014/

Short term...(tonight through Easter sunday)...

Rains are pushing onshore across southern la this afternoon out
ahead of a shortwave trough that is prognosticated to deepen as it approaches
the region tonight. Model consensus is for a surface low to develop
out over the Gulf passing well the southeast of the forecast area tonight.
Strong isentropic upglide on the northwest side of the surface low
will allow rains to begin spreading across southern/southeastern
portions of the forecast area by this evening...continuing through the night.
12z model runs came in a bit further west with the swath of heaviest
rains...although it still appears most of the rain will fall just to
our east/southeast. Still...we could see rainfall totals approach an
inch along the I-59 corridor come tomorrow afternoon...which could
cause some brief rises of creeks and streams...especially those that
are still high from recent rainfall. Do not feel the risk for flash
flooding is high enough to mention in this afternoons severe weather potential statement and will
keep it clear. A few showers and possibly some thunderstorms may be
possible across central and western zones tomorrow afternoon as
daytime instability increases under the upper low. Most of this
activity should diminish headed into tomorrow evening.

Shortwave ridging will build in across the region starting Friday night
allowing dry weather to prevail through the remainder of the Easter
weekend. Daytime temperatures will return to the upper 70s/lower 80s...
which is pretty typical for this time of year. Next chance for
additional rain comes on Monday. /Bk/

Long term...(monday through wednesday)...

Main active period will start Monday afternoon through Tuesday afternoon as a
once phased northern/southern stream 500 mb shortwave trough across the Southern Plains
decouples over the middle MS valley while precipitable waters climb towards 1.3-1.5".
Combination of weak qg lift from southern branch split overtop slightly
unstable airmass /500-1000 j/kg SBCAPE/ Monday afternoon should help
scattered showers/thunderstorms develop mainly across north and central
areas of the arklamiss. Instability will wane into the evening but
with middle level forcing lingering, showers will likely continue
through the overnight. Instability /750-1500 j/kg SBCAPE/ will
return with diabatic heating Tuesday afternoon ahead of a weak boundary
as the positive tilted trough slowly shifts east into Alabama. This
pattern should lead to increased coverage of general thunderstorms Tuesday
afternoon but shear/vertical totals look meager at best to support
anything more robust at this time. Also, widespread heavy rain is
not likely with this set-up and will continue to allow for swollen
rivers to fall. Upper ridging will build back in by Wednesday
morning with a warming trend expected into middle next week. /Allen/


Preliminary point temps/pops...
Jackson 55 71 48 77 / 33 36 2 1
Meridian 53 68 43 77 / 75 64 7 0
Vicksburg 54 71 51 78 / 23 34 1 2
Hattiesburg 55 70 49 79 / 78 42 7 3
Natchez 54 70 51 76 / 20 22 7 3
Greenville 54 73 51 77 / 20 32 1 2
Greenwood 53 72 48 77 / 23 32 2 2


Jan watches/warnings/advisories...