186 
fxus64 kmeg 231743 
afdmeg 


Area forecast discussion 
National Weather Service Memphis Tennessee 
1143 am CST Monday Nov 23 2009 


Update... 
updated for 18z aviation discussion 


&& 


Previous discussion... /issued 1005 am CST Monday Nov 23 2009/ 


Update... 


Kept areas of fog and drizzle through 3 PM and lowered highs a few 
degrees today. 


Discussion... 


Dreary conditions will prevail today. 


At 10 am across the midsouth and forecast area...areas of fog and 
drizzle were reducing visibilities to 3 miles or less in many 
locations. Under cloudy skies...surface temperatures ranged 
between 47 and 55 degrees. Light south winds were occurring. 


Rest of today...areas of fog and drizzle will slowly dissipate 
through the day as low level moisture becomes more shallow. 
Temperatures will not warm up much under cloudy skies...so lowered 
highs in most locations thinking they will only reach 55 to 62 
degrees. Getting breaks in the clouds appears unlikely today or 
tonight with abundant moisture tapped beneath a low level 
inversion around 850 mb. Also...increased temperatures tonight 
a few degrees thinking clouds will not let temperatures fall much. 


Update has been sent. 


Mbs 


Previous discussion... 


/issued 447 am CST Monday Nov 23 2009/ 


Discussion... 
skies will remain mainly overcast across the midsouth through the 
day as low level moisture remains trapped under a strong 850 mb 
inversion. This combined with light southerly surface flow will 
keep temperatures about the same as yesterday. The region should 
remain dry through the day. Some patchy fog is possible mainly 
along the Tennessee River valley later this evening and through 
the overnight hours. 


Strong 500 mb trough will make its push toward the Ohio Valley on 
Tuesday. The associated surface low will push toward the Great 
Lakes and swing a cold front though the area Tuesday afternoon. 
The front will occlude in the vicinity of the midsouth and with 
the lack of decent forcing...believe the area will experience only 
a few light rain showers Tuesday evening. 


Skies will slowly begin to clear Wednesday into Thursday. A much 
stronger 500 mb shortwave will follow the first and bring sharp height 
falls into the midsouth Thursday. Models depict 850 mb temperatures 
in the -4c to -6c range Friday morning which would translate to 
surface temperatures near the freezing mark. Dry high pressure 
from the Southern Plains will then build into the area keeping 
temperatures below normal through Saturday. 


Southerly surface flow will return Sunday as high pressure slides 
east of the area. Surface low pressure will then slide east across 
central Mississippi and Alabama bringing chances for showers back 
to the midsouth Monday into Tuesday. Models diverge at this point. 
The European model (ecmwf) builds another surface ridge into the area. The GFS on 
the other hand depicts a much stronger 500 mb trough digging deep into 
the Southern Plains and slowing the surface low and subsequent 
ridge development. 


Ccd 


Aviation... 


18z taf cycle 


Low IFR ceilings in place at all taf sites with some restriction to 
visibility and patchy drizzle at kmem and kjbr. No breaks in the 
clouds expected across all of the midsouth as cooler air remains 
trapped in the lowest 040ft above ground level. Thus somewhat confident that only 
a small window of MVFR conditions can be expected mainly between 
21-03z. Then ceilings will become IFR/LIFR this evening through 
24/15z. South winds will be fairly light overnight...but 
increasing to 8-10kts after 15z. This will allow ceilings to increase 
more rapidly to MVFR conditions. Improvements not anticipated till 
after frontal system moves into region shortly after 24/18z. 
However...kjbr will see vicinity showers before end of taf period. 


Jab 


&& 


Preliminary point temps/pops... 
mem 60 53 63 45 / 10 10 50 20 
mkl 57 50 61 41 / 10 10 40 20 
jbr 59 52 61 40 / 10 10 50 10 
tup 57 51 64 44 / 10 10 20 20 


&& 


Meg watches/warnings/advisories... 
Arkansas...none. 
MO...none. 
MS...none. 
Tennessee...none. 
&& 


$$