nrgjeff

HRRR tries to get supercells going on the warm front in Mississippi on Saturday. No other CAM (I've seen) agrees. Warm mid-levels. Erratic upper level winds (bad hodograph). Bulk shear is good and so is instability. However I'm real skeptical of anything but a messy blob. Good news for folks who don't like intense severe. Though some wind/hail is likely.

Sunday the ECMWF shows another Gulf MCS keeping Dixie Alley quiet. ECMWF continues a Texas MCS which might not exactly dive to the coast. ECMWF upper levels are suspect, but match the surface scenario. The following is based on the GFS/NAM. 'Murica yeah! The 200/300 mb level winds are little weak and erratic; however, 500 mb is robust and more west than south. Otherwise surface to 700 mb shows pretty good turning. Hodograph is a mess above 500 mb; but, it looks great from 700 mb down. Instability is forecast across Mississippi and Alabama into Georgia. I'm not sure about Tenn. Pattern recognition and some models have a boundary lifting through Alabama. It's left over from the Thursday/Friday system. Front never makes to the Coast. It should lift back as a warm front with quality moisture. Sunday is being monitored for a possible chase. If the ECMWF is right I'll instead be relaxing with family in Chattanooga, lol!

Thursday looks like a mess with JIT moisture and a monster MCS cutting off everything anyway. Weekend (Sunday?) looks better. Moisture will already be in place as the Friday front never clears the Gulf. Upper winds may have VBV issues; but, at least it'll be more unstable.

Thursday severe weather is possible in southern Mississippi. Models forecast adequate speed and directional shear. Appears moisture will be there in time, especially I-20 south. I would focus on the lifting boundary showed by both conceptual models and numerical models. Morning rain is forecast in northern Mississippi. Should keep a lifting warm-front like feature defined. Pre-frontal trough comes in from the west ahead of the cold front, key for robust severe. Right on the cold front is usually trash. Prefrontal trough can be better. Intersection of those boundaries is currently forecast in central Mississippi. More rain would push it toward I-20. Less rain would put northern Mississippi in play.

Probably climate change as we lose the ocean sinks. Oops wrong sub-forum! We are still behind the ENSO spring predictability barrier. Who really knows what will happen next winter? In the mid-term the MJO is a disaster right now for severe. Japan's Himawari satellite loop shows nothing good either. Hopefully it does change by mid-April.

Glad I stayed home and watched basketball this past weekend. Upcoming Thursday I'm not nearly as impressed as SPC. Just-in-time moisture fails in April, kind of like Fed-Ex drivers running you off the highway rushing their JIT deliveries. Wind shear (speed and directional) is good southern half of Mississippi. However that's almost out of our Region and more Southeast sub-forum. Hopefully Wichita State will be playing in the NIT Final Thursday; so, I'll likely be home.

Nashville sounds bullish. Moisture return is slower than models have though. Waze app (Google maps) reports repeating multiple accidents I-24 West of Chattanooga. I'm not sure it's rubbernecking, road rage, or both. Regardless I'm not dealing with that on my way. No storm chase today. NCAA starts in a couple hours anyway.

Parts of Chattanooga and/or Hixson had hail on Monday. I was out of town though. Skiing Utah! Back home now.

Moisture return is still meh. However temps will get well into the 70s. Perhaps it's a good trade-off. Limit tornado risk, but good visibility if anything happens. Upper winds are OK. Low level turning is barely at threshold (IMHO). It's borderline, but it's also almost April.

For severe, per TNI, we could use warmer 1.2 and milder 3.4. Otherwise early severe was a head fake. I still think this KW and other factors (persistent Heartland storm track / Baja SSTs) will bring more action.

March 14 has a thread in Tennessee Valley. I called it Pi Day being a little silly. At first we thought most of the severe weather would be in our region. As it evolved south of the Tenn Valley people just kept going on the thread. Sorry if we hijacked your region. At any rate, it is a fairly interesting thread. Posts show the progression of thought from forecast to nowcasts to reports. Cheers!

We've graduated to Predictability too low. Euro is not as into it. Either has moisture issues or positive tilt. I can understand hesitating there especially day 7. Overall North America pattern is a little flaky too. Just as well we can watch a bunch of basketball before chasing.

Actually I think the North Pacific would keep severe season active this year more than the TNI. Upon reviewing the paper at work. TNI is not the driver attm. However the slightly -PDO may be a driver. Just depends on how the PNA evolves with spring wavelengths. I would think the typical migration from South to Plains, unless the pattern breaks down. Chasers want this current week pattern to be temporary. Get back to southwest flow. On the other hand, a break is nice considering all the flooding from here to Nebraska.

Let's just keep 1.2 a little cool for severe season and TNI. After that I don't care, lol.

I got a thread going. Agree with everything in SPC Mesoscale Discussion 208 just above.

Mid levels look a little warm (SPC notes poor lapse rates / neutral heights) and no clear 2nd boundary is noted. Guess there's always the differential heating between CHA and HSV/BNA. High resolution models show small cells, indicative of warm mid-levels. Perhaps a few storms can get rooted and going, with less coverage. Also 45 knots shear (vs 60 kt) could be slightly less fast storm motion than previous events. Still looks fast though. Sometimes less coverage in Dixie Alley means less sloppy, but it depends on the cause. This situation could still be meh/mess, but with less rainfall (good). In the Plains less (slop) can mean more (quality). In Dixie less is usually less. Almost like snow, Dixie seems like all or nothing. Some statistics actually back up that feeling. Remover the big outbreaks and Dixie is less active than the Plains. Keep the outbreaks and they are equal. This is no outbreak, so I think all is good.

Yes, and we storm chasers are excited. OK, cautiously optimistic.. Another trend is our friend deal: Central Plains had a good snow year. If the active storm track continues, lifting north with the jet stream, it puts the Central Plains in severe wx later in spring. KC had the first good snow winter in years. Will Wichita and others have an exciting spring? Note I've lived in both KC and ICT so I mention them by name. Applies to the whole area. Rock Chalk Jayhawk!

Now a little good news, hopefully... Columbus AFB, Miss. and adjacent radars show some bright banding this morning (Monday). Dual polarization confirms it's mixed precip aloft. Radar estimated (and human estimated) rainfall from the bright reflectivity is probably high. I figure totals are down around a quarter inch. Monday rain was always forecast light. Midweek system even improved a bit. Looks like it'll be moving just enough to keep totals 1-2 inches. Few days ago looked like another 3-4 in. This pattern anything can happen, but think positive.

Saturday March 9, 11:30 central time: Differential heating boundary is evident in North Mississippi, noted by 70s temps south and thicker clouds north. This is south of the synoptic WF which is in Kentucky. The Miss boundary should lift to the Tennessee border, perhaps into West Tenn. As the Arkansas front/dry line approaches, it should create intersecting boundaries, Low level convergence is forecast to increase in MS/TN when the Arkansas front approaches. Conceptual and some numerical models have slightly higher storm relative helicity near the lifting MS/TN boundary. SPC and some CAMs have started to highlight this more southern boundary intersection. Compared to the Kentucky triple point, storms should move slower in the Mid South, esp down in Mississippi. Upper winds are strong both areas, but not quite as much South. Storms are a mess in the Delta right now. We'll see if the line breaks up a bit into Mississippi later this afternoon. We can do without human impacts either way. Perhaps the strongest upper dynamics will outrun surface features, but still plenty of winds aloft into evening.

Sunday tornadoes were an example of intersecting boundaries again. While the synoptic WF made it into the Carolinas, the former coastal front became another warm front in South Georgia. Coldest air hanged back in Tennessee, even as the cold front had made it to eastern Alabama. Hence, arctic air did not surge into the risk area. Alabama cold front acted more like a pre-frontal trough, with the coldest air back in Tenn. Georgia warm front intersected Bama trough in Lee County. Damaging tornadoes continued east from there along the WF. Other tornadoes were in the free warm sector. SPC did a good job going hatched in spite for CAMs slop/lines. Of course our thoughts and prayers are with the victims. Next chance of Dixie Alley severe is back in our region, but Day 6 nobody needs to worry yet. If moisture returns (currently questionable after arctic front) the Mid South should see a potent short-wave on Saturday. Main storm system ejects north. Southern energy is progged however, including gradual turning with height. (remember just day 6 models) Later next week, out around Day 9, is another possible day. A little more moisture may be available. First system would start that process, if its front does not get to the Gulf Coast. Both of these could be nothing though. Just things to watch in March.

Well at SPC Broyles goes ENH for Sunday southeast Alabama into parts of southwest Georgia, including 10% hatched tornado. It's aggressive but some CAMs have broken cells. I'm not too interested. Terrain is mostly poor except south side of ENH. The 700 mb level offers wind direction challenges, except farther ahead of the trough. I suppose best cells would be ahead of the main line. Positive tilt just does not give me that feeling. Though 925 mb may be less veered ahead of the line. We'll see. Probably should post in the Southeast Region but I have not been in here for 3-4 days. Happy weekend!

Hells bells. I'm siting in Chattanooga wishing I'd rolled out to Florence, AL. MCS coming out of Arkansas may be messy. However Mississippi and northwest Bama are destabilizing along and south of an outflow boundary OFB. I now believe this OFB will be a focus for enhanced low level shear when storms reach it. Even more bullish, descrete cells in the free warm sector (Mississippi) heading into the said OFB would likely ramp up upon arrival. Not sure for how long, because it's stable on the other side. Still, it is a focus area. Quasi dry line coming from central Arkansas may still refire behind the MCS. However I'm not a fan of right on the DL if a pre-frontal trough is available and looks promising. Appears the latter may be on the Mississippi River as I type Noon Central Time. If I had departed on time I might target intersection of this pre-frontal trough and outflow boundary 2nd paragraph. Oh well, plenty of college hoops on today, lol!

00Z CAMs (convective allowing models) have a couple different solutions. NAM high-res focuses on the quasi dry line coming out of Arkansas. ARW version of the WRF has storms going up on a pre-frontal trough a little farther east, starting in West Tennessee and Mississippi. HRRR wants to light up both. Agree that seems a little too aggressive. Adding to low-level shear should be a morning rain induced boundary lifting north from Alabama into Middle Tennessee. Should be more stable north and east of it. The quasi dry line storms might be a little forced, perhaps a broken line, but with a few rotating. Deep level shear is impressive. I call it a quasi dry line because colder air lags behind with a separate wind shift. If the pre-frontal trough becomes dominant, the storms could be more beefy and discrete, but perhaps sloppy. Low level shear is even a little better there. However storms would run into more stable air sooner. Again I really don't think both will go this set-up. Happened before in Dixie, and the Plains for that matter. However Saturday the instability axis may not be wide enough to get both going. Have to wait until morning to decide which one, or even nowcast it later.

Friday Excessive Rainfall Outlook is upgraded to High for parts of North Alabama, southern Middle Tennessee, northeast Mississippi and other adjacent areas of Tenn.

Saturday severe risk has held up with data today. Just a look at the surface chart and visible satellite shows the Gulf air boundary is onshore and moving north. It will stall in the Deep South Friday as heavy rain pounds the Tennessee Valley. Then it is forecast to lift north Saturday, but probably become a little diffuse as the synoptic warm front lifts to the Ohio Valley. A couple days ago, I saw some veer-back-veer VBV on upper air forecasts around 700 mb. Most of the VBV is gone now. Forecast hodographs have that big but gentle curve up through 200 mb. Believe the presence of a more defined southern short-wave has created the more textbook upper air charts. Check of forecast helicity index confirms the drill down (or up) through the forecast charts. Instability remains a question. Severe weather really does not. This forced set-up will at least have a lot of straight line winds. Saturday morning MCS is generally forecast to lift northeast. However it could continue straight east and contaminate the warm sector. MCS lifting out and leaving behind an outflow boundary would be more favorable for tornadoes, iff enough breaks of sun can destabilize things. Looks like a good one to track from home. Could be high water spots on roads. Storm motion will be fast. Visibility may be low with tight T/Td spreads. Terrain is hit and miss. Couple huge college basketball games are on Saturday. While wind shear parameters are solid, it may just be forced winds without more instability. Of course the door is open for a greater tornado threat though. Separately, those Excessive Rainfall charts might be of interest in the Event thread for heavy rain and flooding. No worries about today, but I bet they stay robust next update.