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Nowcast

• 

• Now as of 12:40 PM CDT on May 19, 2013

  At 1 PM...partly cloudy. Isolated showers and thunderstorms. Temperature around 84. South winds around 10 mph. At 2 PM...partly cloudy. Isolated showers and thunderstorms. Temperature around 85. South winds around 12 mph. At 3 PM...partly cloudy. Isolated showers and thunderstorms. Temperature around 87. South winds around 13 mph. At 4 PM...partly cloudy. Isolated showers and thunderstorms. Temperature around 88. South winds around 14 mph. At 5 PM...partly cloudy. Isolated showers and thunderstorms. Temperature around 88. South winds around 13 mph. At 6 PM...partly cloudy. Isolated showers and thunderstorms. Temperature around 87. South winds around 12 mph.

Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Sunday
• 
• High: 90 °
• Low: 66 °
• Partly Cloudy

• Monday
• 
• High: 88 °
• Low: 70 °
• Partly Cloudy

• Tuesday
• 
• High: 88 °
• Low: 64 °
• Chance of a Thunderstorm

• Wednesday
• 
• High: 82 °
• Low: 64 °
• Partly Cloudy

• Thursday
• 
• High: 90 °
• Low: 63 °
• Chance of T-Storms

Area forecast discussion...updated 
National Weather Service Jackson MS 
957 am CDT sun may 19 2013 


Update...latest satellite imagery showed the region under the 
influence of a shortwave ridge with weak moisture convergence...which was 
being flanked by a strong upper trough over the plains and short 
wave troughing over the southeast US. Stratus was noted over the 
region this morning...which will lift for this afternoon for partly 
cloudy skies with high debris clouds coming from the plains system. 
Area soundings showed good lapse rates across the region of around 
8c...with convective available potential energy around 2000...with good drying from 900 to around 
500 mb above the low level moist boundary layer. Dcapes across the 
south were around 1200 with cold pool height at 598 mb at 61f. Precipitable waters  
were generally around 1.2 inches . Latest NAM shows cape exceeding 3000 
j/kg with showalter index around -6 centering across the southwest. 
A few WRF models were showing some isolated showers and 
thunderstorms across the south half for this afternoon with the Storm Prediction Center 
WRF showing an isolated strong storm in the southwest. Latest RUC/NAM shows 
some low level moisture convergence at the 1000-850 mb level for 
this afternoon...mainly along and west of the MS river. There is the 
potential of one or maybe two storms across the south half with some 
potential to be on the strong side. Will hold off on mentioning that 
in the severe weather potential statement since the potential for development is on the slim side. 
So have put in teen probability of precipitation across the south half for this afternoon. 
Will monitor for any development and reconsider the severe weather potential statement for later. 
Otherwise have adjusted the sky grids with the latest 12z NAM 
guidance for a little more cloud cover for partly cloudy skies. 
Current highs in the middle to upper 80s looks to be on track./17/ 


/previous discussion...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 would 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...remaining stratus/br should gradually mix out/burn off 
through the remainder of the morning...with a mix of cumulus at 
030-040 and some cirrus expected in the afternoon. Winds will be 
from the south and gusty at times...particularly in the Delta as 
25-35 knots 925 mb flow mixes out. There could be an isolated storm or 
two developing in the afternoon along and south of I-20...but the 
chances of any impact to aviation operations in the Aerodrome is 
very minimal. Generally expect a repeat as far as stratus 
development for tonight as we are seeing this morning. /Bb/ 


&& 


Preliminary point temps/pops... 
Jackson 89 70 89 70 / 16 4 8 9 
Meridian 88 68 90 66 / 16 4 7 8 
Vicksburg 89 70 90 70 / 16 5 9 10 
Hattiesburg 88 70 89 68 / 20 4 9 6 
Natchez 89 71 88 70 / 18 4 10 7 
Greenville 90 71 89 70 / 10 6 9 11 
Greenwood 89 70 89 69 / 10 6 9 10 


&& 


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


$$ 


17/bb/08/22