095 
fxus64 kjan 222004 
afdjan 


Area forecast discussion 
National Weather Service Jackson MS 
304 PM CDT Thursday may 22 2008 


Short term...main concern is the convection ongoing as I type. An 
upper low will continue to traverse across the area and this will 
continue to provide the support for rain showers and thunderstorms and rain. A few of these 
will still have the potential to be strong to severe through the 
early evening hours. Lapse rates and ample instability will still be 
sufficient through the Earl evening and help a few storms to become 
severe early this evening. As we lose the heating of the day the 
intensity of these storms will wane and then most if not all 
convection should be done by 4z. In addition to the strong/severe 
potential...heavy rain could be an issue as well. Ample moisture is 
moving in from the south and with convection expected to continue 
and move slowly to the north some areas across the south could see a 
good bit of rain in short while. 


Tomorrow had been looking a little wet but latest run of the GFS has 
trended quite a bit down on the probability of precipitation. The biggest change I notice is 
the amount of moisture the GFS is suggesting. Previous runs were 
bringing precipitable waters  to near 2" and now the GFS has 1.3-1.6 over most of the 
area with the southern zones approaching 1.75". With the area 
actually under a building ridge the moisture was about the only 
thing in the positive for convection to break out. Now with the 
lower precipitable waters  it contains most of the convection could remain confined 
to the Highway 84 corridor. The GFS also had been holding on to a little 
left over lift from our disturbance today but now that is not the 
case. Gui values have come down in response to this and with the NAM 
pretty much agreeing with this scenario I will just stick close to 
the mav values and keep convection contained across the southern 3rd. 


Heading into tomorrow night any convection that is out there will 
quickly come to an end after sunset. The ridge will continue to 
build through the night and this should help keep things quiet into 
the weekend. 


As for temperatures...look for things to be on the warm side with very 
humid conditions in place. Heat could become a little problem across 
the west as highs in the lower to maybe the middle 90s and dewpoints 
near 70 leading to heat index values approaching 100 degrees. Lows 
will also have a hard time dropping much below 70 tonight and they 
may stay in the lower 70s over some areas Saturday morning. With 
heat index values near 100 and lows only expected to get down to 
near 70...this could cause some minor stress on people and outdoor 
pets as it will be a little difficult to cool down overnight. As for 
gui I have made no adjustments to gui values. /Cab/ 


Long term...Saturday through next Thursday...some rain chances look 
to persist each day across at least a portion of the forecast area 
through much of the long term. The better rain chances look to be 
Saturday into Sunday as a "back door" cold front is prognosticated to shift 
across the forecast area. The presence of this front moving into and 
across the area Saturday has caused ME to increase probability of precipitation during this 
time...as it'll encounter the warm moist and unstable airmass 
residing over the area then. The better probability of precipitation will be across the south 
where the better moisture and instability will exist. 


We could see an isolated strong to severe storm during the afternoon 
hours Saturday...especially in the west and southwest. Although 
heights look to be rising during this time...as the boundary drops 
into the area and encounters this moist and unstable airmass...once 
daytime heating is factored in as highs are forecasted in the low to 
middle 90s...we could see some storms begin to try and develop over the 
region. Since there is some slight inconsistencies in the models as 
to when exactly this "back door" front will actually move into the 
area...i'll hold off on mentioning this possibility in the severe weather potential statement. 


Behind the front...look for some drier air to move into the region 
from the northeast bringing an end to the rain chances. Some 
isolated showers and storms will still be possible over mainly the 
west central and southwest portions of the forecast area Sunday...as 
the front is expected to hang up near that area. 


After Saturday...no changes will be made to the long term portion of 
the forecast this afternoon. The previous long term forecast 
discussion follows beginning with Monday. /19/ 


Monday through Thursday...the upper ridge will begin to flatten on 
Monday...but the surface ridge will begin to strengthen over the 
area Tuesday and especially on Wednesday. The GFS/Euro indicate that 
precipitable waters  will fall below an inch over most of the area on Tuesday and 
Wednesday. Diurnal isolated storms will still be possible over the 
area Tuesday...but expect Wednesday to mainly be a dry day. The GFS 
indicates that another backdoor cold front may try to push into the 
area by Thursday. 


Stuck pretty close to guidance with temperatures and probability of precipitation through the 
period as there really aren't any targets for improvement over 
guidance in the extended. /15/ 


&& 


Aviation...main concern is the convection. Rain showers and thunderstorms and rain will be 
possible across most of the area but the most likely sites being 
affected look to be hbg/Jan/glh. There could even be a few severe 
storms with large hail and damaging winds possible. All convection 
should come to an end around 4z and the rest of the night should be 
relatively quiet. 




&& 


Preliminary point temps/pops... 
Jackson 68 93 72 92 / 13 11 5 16 
Meridian 67 91 68 93 / 14 20 5 15 
Vicksburg 69 94 71 93 / 15 11 5 17 
Hattiesburg 68 91 72 93 / 34 32 16 25 
Natchez 68 91 71 92 / 30 16 10 25 
Greenville 70 92 70 94 / 15 11 4 13 
Greenwood 69 93 71 93 / 14 11 4 12 


&& 


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


$$ 


Short term/aviation: cab 
long term: 19