Area forecast discussion...updated 
National Weather Service Jackson MS 
925 PM CDT Thursday may 23 2013 


Update... 
overall the rest of the evening should be fairly quiet as the cold 
front is currently situated along the I-20 corridor. This frontal 
boundary should move through the region overnight. High instability 
and upper shortwave in the 500 mb northwest flow aided in some 
shower/thunderstorm development in the far southwest. Kept some probability of precipitation 
in the far southwest for the next hour or so before these storms 
will weaken. Due to this activity in the southwest and approaching 
high clouds from convective activity in the Texas 
Panhandle...increased lows slightly in the southwest. Also removed 
patchy fog for most areas due to the high clouds moving tonight but 
left it in the far southwest due to the rainfall that has occurred 
today. Adjusted hourly temperatures/dewpoints/sky grids according to 
current trends. Rest of the forecast is on track. /DC/ 


&& 


Aviation...expect a quieter taf period this run with VFR conditions 
prevailing for most sites. A weak surface front has entered the norther 
County Warning Area and will continue to push south overnight. Additionally...deep 
mixing allowed for lower 60 dewpoints to be realized across the eastern 
half of the area and crossover temperatures will be tough to achieve...thus 
not expecting visible to be reduced. The exception may be at hbg and 
will cover with a 2hr tempo for 5sm. Sky clear conditions for Friday with a 
north-northeast wind at 10-15kts. /Cme/ 


&& 


Previous discussion... /issued 400 PM CDT Thursday may 23 2013/ 


Discussion...a bit of convection is trying to form currently across 
central Louisiana in an axis of high instability...modest moisture 
convergence and upper level atmospheric lift. This is basically 
where an mesoscale convective vortex (mesoscale convective vortex) embedded in northwest 
flow aloft is impinging on a cold front oozing south. Broad spectrum 
of global nwp models and regional hires models are still in 
disagreement on convective development through this evening in our 
vicinity. Our thinking is that there will likely be at least an 
isolated storm or two in southwest zones late this afternoon through 
this evening which could produce at least some brief gusty winds or 
small hail. This risk was highlighted in the severe weather potential statement. We will also have 
to watch out for the "worst case scenario" offered by a few hires 
models...which is a small vigorous thunderstorm cluster or two 
developing over the next few hours and pushing across southwest half 
of zones through this evening. This worse case scenario might bring 
a risk for wind gusts to severe levels but fortunately latest trends 
suggest the worst case scenario not too likely. 


Otherwise for tonight...anticipating the cold front now slipping 
down from the north to pass slowly through most of the region by 
dawn tomorrow. Although the air mass trying to come in behind the 
boundary is relatively cool for the date...clouds and some lingering 
breezes will prevent optimum radiational cooling from occurring. 12z 
mav lows looked good...advertising a range of upper 50s north to middle 
60s south. Also Worth mentioning is that there could be some patchy 
fog in southern zones come late tonight...but fog should definitely 
not be as big of an issue as it was this morning. 


Through tomorrow and into the weekend high pressure will take up 
residence over the southeastern Continental U.S....although the coolest and 
driest air will definitely be centered east and northeast or our 
region. The cold frontal boundary will stall not too far to our 
southwest and could kick off some modest convective activity during 
this time. For that reason rain chances will be low...but not zero. 
More operationally-significant will likely be the fact that the 
close boundary and intermittent convection to our west should shoot 
some higher clouds periodically our way. This cloud cover will 
likely keep temperatures a little warmer tomorrow night and Saturday 
night than the extremely cool 12z mav suggests. But even raising 12 
mav lows for Friday night a touch suggests a few record lows could 
be in jeopardy for the 25th. High temperatures should probably only 
be a little below average in most spots...although locations up 
north along the Highway 82 corridor could see highs remaining in the 
upper 70s tomorrow. 


The front will be starting to return north by late Sunday as a weak 
disturbance passes to our north. The interaction of this front and 
the disturbance will bring chances of showers and storms...but 
mainly to our north. So after this evening we have kept the forecast 
dry for all areas until around the middle of next week. The previous 
long range discussion is posted below for reference. /Bb/ 


Previous discussion... /issued 415 am CDT Thursday may 23 2013/ 


Long term...(sunday through thursday) ridging begins to give way 
Saturday night with a shortwave moving through to flatten flow. The 
Euro is advertising stronger forcing with this wave and brings an 
area of moisture/precipitation across northern zones for Sunday. The higher probability of precipitation 
called for by the Euro for Monday after the waves passes look a 
little out of whack...weak isentropic flow notwithstanding...and the 
more consistent dry forecast per the GFS will be followed for now. 
Model solutions continue to differ in the farther periods of the 
extended regarding placement of the upper Ridgeline and shortwaves 
that push through but the general pattern will be low level southerly flow 
in a region of weak upper forcing possible depending on where the 
ridge/trough positions set up. In this type of regime the chance of 
afternoon convection...even without significant forcing...will 
gradually be on the increase due to persistent southerly flow that will be 
in place. However models are also suggesting a potential for capping 
due to the proximity of the upper ridge. Due to these uncertainties 
the drier GFS will be followed for now. /03/ 


&& 


Preliminary point temps/pops... 
Jackson 64 83 52 84 / 11 6 2 2 
Meridian 61 82 46 84 / 8 2 0 0 
Vicksburg 65 82 54 85 / 13 7 5 6 
Hattiesburg 67 86 51 86 / 10 5 3 2 
Natchez 69 83 55 83 / 15 9 5 7 
Greenville 63 79 54 82 / 11 3 2 4 
Greenwood 59 78 50 82 / 7 1 0 0 


&& 


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


$$ 


District of Columbia/cme/bb/03