Sunday, January 31, 2016

Tuesday Update

Current SPC Outlook
Good morning everyone. I will not beat around the bush so I will dive right into things. Based off current data (the 06z runs) I feel the threat for some severe weather is still there for Alabama overnight Tuesday. The one thing is the overall tornado threat seems to be diminishing but not gone. Basically making the main threat for Alabama damaging straight line winds along the squall line. INSTABILITY: Temperatures will be in the lower 70s and dewpoints in the lower 60s. 3pm 2meter temps
Dew Points at 6pm
The GFS and NAM are only indicating about 250-500 j/kg of CAPE from 3 p.m. to midnight window. While yes this is more than enough to produce thunderstorm updrafts, but they won’t be intense. GFS SB CAPE VALUES at 6pm Tuesday
NAM CAPE VALUES at 6pm Tuesday
WIND SHEAR: The overall wind shear needed for organized thunderstorms will certainly not be lacking as bulk shear values will be over 60 knots. Low level helicity will be very high as well. The GFS and NAM rate it at over 400 m2/s2, which is almost too high. Bulk Shear
The Significant Tornado Parameter is greater than 1 over Central Mississippi at mid-afternoon and nearly 2 over northern Mississippi by sunset, but goes down as the sun sets.
The entire system is a bit slower than this time 2 days ago. With this happening now the main area of concern for significant tornadoes will be north Mississippi and western Tennessee as storms in these areas could be supercells and will be occurring during the prime heating of the day. With that in mind I have adjusted my threat map accordingly.

Saturday, January 30, 2016

Tuesday Severe Update Model Madness

Ok now that the mesoscale models are able to get into the mix we can start getting a better understanding on what we can expect next Tuesday. Right now per the Global models the system has slowed a bit and pulling back to the north and northwest with the greater dynamics. Looking at the GFS and other global models the trough seems to be slowing a bit and going more of a positive tilt which which helps lessen the threat of a major severe weather event. If you base the entire forecast off of the GFS model.
Now don't take that likely because the threat is still there and it is still real just a tad lesser than this time yesterday. Right now this morning this is looking like a High Shear Low CAPE type event with the GFS CAPE values around 500 j/kg and the EURO is putting out values about 750 j/kg which is high enough for severe storms to develop but could limit the overall strength of the storms (but they can still be extremely dangerous) Again if you base the forecast off of the GFS models. GFS CAPE Values at 6pm Tuesday
GFS SRH values at 6pm Tuesday
Now the mesoscale (NAM) is in and actually is able to go out thru 6pm Tuesday and here is what we see with that. CAPE Values at 6pm
Significant Tornado Parameter 6pm Tuesday
SRH 6pm Tuesday
Bulk Shear values are very impressive as well
With all that said all the dynamic and thermo dynamics profiles suggest severe weather. Even though the trends are a tad weaker than yesterday and based on what I am seeing I am adjusting my threat map just slightly to the NW
Also for those of you asking about a timeframe here is just and educated guess based on current speeds of the system from all models.. West Alabama 5-8pm Central Alabama 7-10pm East Alabama 9pm-2am Now remember there will be a few more adjustments to be made over the next couple of days as with each run there is the chance the trough digs into the area faster and the all the severe parameters increase or decrease each time. I will update as needed. Just be prepared by having a plan in place and make sure your NOAA WX Radio is working properly.