Roger J Smith

1600z 9 May Red alert, hope the chasers get this breaking info ... Today's set-up has modified due to the development of a wave on the cold front in northeast Texas after 18z. Surface obs show that hot, humid air is pooling across southeast OK and most of eastern TX this morning (it's now 1100 CDT). For example, dew point at Ardmore OK past hour was already 24 C. 12h progs show wave developing near DFW and moving east-north-east to trigger the major outbreak expected tomorrow. I think this may result in a tornadic outbreak today in areas just east of DFW, possibly around Longview to Texarkana. At this time, some heavy to severe storms already firing in s MO and n AR but these are likely to be beyond the storm chasers' reach, would suggest dropping south more than east through eastern OK to await developments in a location like McAlester or Fort Smith. I will post an update on development including the best radar around 18z. As for tomorrow, the progs now indicate massive potential in the area of Nashville TN to Birmingham AL, with a rapidly deepening low across IL and MI creating strong cold fronts; this outbreak is sure to produce major tornadic activity and will last through Wednesday night into Thursday in the Carolinas if you want to keep tracking severe storms that far east. Looks like a 30-40 (F) temperature drop setting up behind these fronts, from the mid 80s to the high 40s. Would not be surprised if there is a rash of destructive storms tomorrow afternoon and evening across KY, TN, n AL-MS. But as for today, best chase conditions may eventually develop in northeast Texas or extreme southeast OK into s.w. AR and n.w. LA. Update at 18z

Not sure if the team has the inclination to drive long distances to find severe storms, but this situation will become quite mobile tomorrow. I think Tuesday's main round of severe storms may begin in e KS-OK into w MO but may eventually transition into s/c MO and northern, western Arkansas. That's quite a drive from western Kansas. Then on Wednesday, the progs are suggesting a more severe outbreak with a classic battle between the moist Gulf air and strong cold fronts drawing in cold air from central Canada. This battleground will probably be strongest across KY, TN, n MS and n AL. After that, the western theatre re-activates Thursday into Friday. I think the Wednesday action may be worth chasing despite the distances, F2-3 tornadic potential seems almost guaranteed with this set-up, would suggest Tupelo MS to Birmingham AL as the target zone later Wednesday, Tulsa n.e. to Joplin, then over to Jonesboro in n.e. AR for Tuesday.

7 May _ 0350z From the 00z progs just out, looks good tomorrow afternoon for areas west and northwest of Lubbock. Then on Monday, with a rather weak cold front across the Oklahoma panhandle and Kansas from s.w. to north central, the risk zone seems likely to be centered near Garden City KS but may include parts of the Texas panhandle again. Haven't been there, but the OK panhandle features semi-arid canyon type terrain on a small scale. I was in Garden City KS once, TRW+ all night. Then 102 F the next day as we travelled east. Not likely to become a big tourist destination. :blink:

I was mostly going by what Paul said the team was planning to do -- the forecast models have been showing some risk of severe storms in KS and nw OK on Monday, but also an area of TRW+ in the Texas panhandle. We'll see what they decide after today's action, could be that they will decide not to go that far north with some chance of more action in Texas tomorrow. The Monday-Tuesday scenario is not too clear yet, but I would rate it at slight risk for western half of KS and nw quarter of OK based on what I've seen of 12z model runs. Texas is not closing down however, and the recent activity there provides low level moisture so it needs to be considered whether any move is required. Would base more on 00z model runs as the western U.S. front is very slowly developing today. (I am looking out my window at part of it, nothing much going on here).

2015z 6 May No doubt the team have taken up a position near or south of the developing supercell currently located just north of Junction TX, about an hour's drive south of Brady. Nothing else showing on radar within striking distance. This cell may begin to move fairly rapidly east soon, currently drifting along at 20-25 knots towards the east.

Good position, I just saw an updated satellite and radar, cell potential in that area appears good, especially considering the moist conditions after the heavy rains last night in the region. I believe a major outbreak will develop between Brady and Temple later this afternoon. Other zones will also become active, but this may be the general area to chase today. Radar link for the area: << http://www.weatherimages.org/radar/ksjt.shtml >> Brady is in the county southwest of Brownwood (it's the county seat at the confluence of the various roads in that county). As of 1850z when I posted this, severe cells developing west of Brady near Sonora. The smaller cell to the southwest could become tornadic. The image will update so later readers will find this radar probably developing into larger clusters of severe storms.

You may find storm development quite close to Brownwood in 2-3 hours. The activity further south may also be severe, but current radar and surface obs suggest a developing front lying E-W just to the north of Brownwood towards Waco. Especially as you are planning a long drive north Sunday, you might want to consider drifting east towards perhaps Clifton TX northwest of Waco. From there you could catch the north-south interstate through DFW and OKC and I assume you're heading for Russell to Hill City KS for Monday?

I suspect that the chase team followed the severe storm cluster across central TX and may have decided to keep driving southeast to be in a better location for today's redevelopment. That could have involved a 4-6 hour drive. The remnants of the severe storms are now in the Houston area but the frontal zone will probably redevelop later today further north around Temple, south of Waco. A position between Temple and Austin in east central Texas is recommended for today's operations.

Things may work out well from this location. Cell development is rather gradual, one minor TRW near Fort Stockton about 75 miles to the west of team's location. Another cluster in s.e. NM showing signs of more rapid development. However, in about two hours the portion of the dry line between these cells may also get active and then the present location could be ground zero for arrival of tornadic storms around 00z to 03z or 7 pm to 10 pm CDT. Winds at Guad Pass have picked up past hour which is a good sign of dry inflow and 2-3 hour signal for TRW+ development.

1600z 5 May Would agree with Gorky on the general risk zone being somewhat to the south of Lubbock, a position between Odessa TX and Hobbs NM possibly just inside the s.e. corner of NM may be the spot today. Surface low forming in NM with n.w.-s.e. trough will allow convergence of low level moisture around a developing triple point near Hobbs NM, so over NM there may be some TRW+ drifting southwest later today. With a dry line punching into the moist Gulf air from approximately Hobbs through Kermit to the Big Bend (this is sounding more like Sesame Street than I intended) best risk zone for severe weather is likely to be along the quasi-stationary front already well indicated by temperature and cloud contrast lying just south of Odessa to north of San Angelo. Anywhere along this frontal zone should see some risk of supercell development but for max risk I would suggest a position as close to the southeast corner of NM as roads will allow, either side of the state line. Development should be fairly steady today, not a late bloomer but then lasting well into the night as the wave forming in NM ripples e.s.e. along the frontal boundary. This may mean that storms of interest will move little at first and then begin to trundle e.s.e. later. Saturday's max risk is probably further east between Brady and Temple. Could be more tornadic than today.

Here's the Lubbock radar -- should update, check the time at the top of the image. << http://www.weatherimages.org/radar/klbb.shtml >>

2300z update I suspect the team is on the move because they are not on line and haven't been for about an hour. The frontal zone is taking better shape now and lies in a line WNW-ESE through Lubbock TX. Cells are developing fairly steadily along this frontal zone while the earlier discrete cell in Floyd county is now weakening. The most active (2) cells are those 30 miles west of Lubbock and 20 miles ESE of Lubbock. Both clusters appear likely to produce 2-3 inch hail and wind gusts to 70 mph. The environment appears too dry for tornadic development (dew points are in the lower 60s at best on the south side of this front and in the 30s F north of it where winds are NE 15-30 mph). If the team is going on radar and visual clues, they will probably be heading south from Matador TX towards the line of storms (I hesitate to call it a MCS because it lacks the usual clustered development and counter-clockwise cyclonic system movement, the cells are moving more ESE than SE to SSE). If they have a chance to adjust direction, I still think the strongest storm in this complex is the one west of Lubbock and sunset storms around Lubbock often produce very severe weather (this type of storm usually peaks around 7 to 10 p.m. because of the limited moisture available, the first part of the development cycle is "wasted" on getting any kind of development to begin.) Tomorrow actually looks like a more severe storm potential developing as this frontal zone should refire with more energy available. Looking forward to the reports.

As of 22z I think the only chance for interesting viewing within reach would be around Lubbock in 2-3 hours. Cells now on NM-TX border should develop further and drift ENE or due E towards a point 10 nm Lubbock by 01-02z. Whether it's worth the 2 hour drive for what amounts to a 50-50 shot at seeing anything severe is the question ... I see less chance for development between Lubbock and Childress than further west.

Tough call, all sectors within reach have marginal development next 2-3 hours. Would suggest you edge ENE since a third area of cell development near Clinton OK may turn out to be strongest after 5 pm CDT and in any case is closer to you. You might even do OK to stay put. Dry line front appears to be edging back WNW at present, later convection may fire near your current location. But the odds favour a slight move ENE into w OK. I am expecting more significant development after 23z or 6 pm CDT peaking around 02z or 9 pm CDT in western OK and the Texas border regions closest to Wichita Falls.

I didn't have to put up with it, but surely that was the most boring month of weather in recent memory? Not that we did any better here.

The following link will give an updating infra-red satellite image for the USA and southern Canada. << http://weatheroffice.ec.gc.ca/data/satelli...am_1070_100.jpg >>

30 April 06 _ 1625z Would advise the chase team to hold tight in the area between DFW and SPS (Wichita Falls) tonight, awaiting gradual development in that area tomorrow. Only a slight chance of isolated TRW+ in western Texas later today as a weak thermal low is developing west of Midland TX but most of TX and OK are under a weak ridge This feature will slowly intensify tomorrow with a weak surface ridge over Oklahoma and a trough from near Midland to the TX-OK border around Ardmore OK. This trough likely to become the focus for TRW+ development with some supercell potential. Best threat zone is likely to be somwhere between Wichita Falls and Graham TX. Would suggest Mineral Wells TX as a good Monday morning position, development is likely to come after noon CDT. This is about a 90 minute drive from Fort Worth west on the interstate highway.

Things appear to have slowed down a touch, which means that a major severe weather event later today in TX and OK will not be that far to the east when you arrive on the weekend. Today, looks ripe for development of heavy rainfall over many of the regions recently plagued by drought and blowing dust, central OK to n/c TX. This may be beneficial in the long run but the first stages may involve some serious flash flooding even in the DFW area. Large hail and tornadoes are indicated for portions of w OK, nw to n/c TX centered on Wichita Falls to Abilene (that's later today) ... by Saturday this system will be somewhat weaker and into Missouri and Arkansas, Louisiana and Mississippi. If you're not chasing after that one, the advancing system appears to be slowed by about half a day ... would now seem that a position in nw KS, ne CO or se WY might be best advised for late Monday with development then and on Tuesday in the general area. I think that by Tuesday this may turn into a good storm chase situation with separated cells in a fairly dry environment generally giving good visibility of TRW+ and some risk of tornadic development. Actually, just as well, time to get oriented to the heat and humidity as well as driving on the right, etc etc, then a slow buildup to some interesting weather. If you guys get bored with the weather or it stops producing for a few days, western Colorado and southern Utah are very scenic and that's where my avatar photo was taken (Bryce Canyon National Park). Always very interesting cloudscapes across this region, I've found on my various visits. A more accessible location that is similar would be Big Bend National Park in western Texas. ------------------------------------------------------------ Just for general interest, probably more for the readers in the UK than the experienced storm chase guys, here's some information on the climatology of Texas and Oklahoma that you may find interesting and helpful in understanding severe weather in that region. Most severe weather in the southern plains occurs when low pressure forms over NM, w TX or CO and high pressure is located over the eastern Gulf. The moist, humid Gulf air mass usually moves inland rather slowly but as it moves north, the humidity also rises gradually to the west due to low level moisture feed from the SE. The dynamic cold front of the system tends to separate dry desert air from northern Mexico from cooler Pacific air. This leaves the warm sector divided into moist and dry tropical air masses that become separated by a "dry line" feature. In some cases, this dry line is under a cap or inversion, and the only effects on the weather are found in weak lines of cumulus or even altocumulus with a rather gradual dew point gradient across the dry line. Wind shifts then are often marginal, from SSE to SW. However, when the dry slot air mass starts to move faster and cut under the humid air near the surface, wind speeds often accelerate, especially through various gaps in the north-south mountains in west Texas. A station called Guadalupe Pass east of El Paso often signals the onset of severe conditions when winds there start blowing in the range of 45-70 mph from the SW. When El Paso and other nearby stations in se NM hit 30-40 mph winds in this situation, severe storm development may be imminent. A favoured location for onset of these storms is near or just west of a line from Amarillo TX to Lubbock TX at about 2-4 pm CDT or 19z-21z. The normal pattern is for cells to be isolated at first, then more continuous by the time the dry line reaches the TX-OK border and south. These dry line storms usually hold together to about OKC-DFW but after this, the dry line feature and its storms may begin to fade and more development then takes place as the actual cold front catches up to the dry line and plows into the warm sector which in this stage is beginning to lose the dry slot feature. This is the main reason why storm chase results are usually better west of OKC to DFW than east -- the storms are more separated and surface humidities are lower, leading to better visibility of the storm effects. Further north into KS and NE, the same kinds of dynamics occur but the dry line conditions make more progress east due to the distance from the Gulf. There are occasions when the dry line can still be detected as far east as Iowa and northern Missouri. If the fronts make any further progress, they rapidly transform into the more familiar polar and maritime fronts and the dew points between them usually rise to levels more typical of a transitional air mass in North America, 15-18 C. Returning to Texas, large hail is often reported in central Texas. There are probably more large hail than tornado damage reports from areas between San Angelo and San Antonio, and large hail is fairly frequent as far north as southern Kansas. Even in North Dakota and Manitoba, in mid-summer there are reports of large hail on a fairly regular basis. The typical supercell thunderstorm has a tornadic development zone near its southern boundary and a large hail production zone just north of that, with heavy rainfall at that location and further north in the cell.

Let's hope that one day, the title of this forecast thread is Thundery Winter Showers.

With that large high drifting ever closer to Europe from the northeast, there is probably more chance of a warm month than a cool month. However, the flow would be east to southeast a fair amount of the time and the North Sea has been chilled by the run of colder than average months around its shores (especially the other shores). Nevertheless, I think May could challenge the outlier of 1833 which I believe was a degree or more warmer than all other Mays at 15 C. So let's say 13.7 to put the prediction between the pack and the record. I have the feeling there will be long warm spells in May this year, the only question being, very warm or just slightly warm? Mr Data -- any idea how the extreme warmth of May 1833 developed? I notice from the CET records that it was almost but not quite the warmest month of the year! (July was a little warmer).

Isn't there a certain irony when people spend more time discussing the second decimal place of the CET than they do investigating new research or thinking about the larger scale processes at work in the atmosphere? (by the way, the answer is yes) :blink:

Just had a look at latest 12z progs for central US on 1-2 May, seems that the severe weather will be located in two areas, one around Atlanta GA to Birmingham AL and the other in western ND-SD by the evening of 1 May, then more into MN-IA-ne KS-nMO by Tuesday. Neither outbreak looks super severe at this time, but the northern one is more likely to provide good viewing conditions for the chase. It's a long drive from DFW to Winner SD, but that's where the action is likely to be on Monday.

As I mentioned in another thread, reduction of ice cover in the Canadian arctic (the Beaufort Sea in particular) has been linked to albedo changes that result when increasing amounts of sooty particulates are transported into the arctic from eastern Asia and dropped onto the ice pack. Even if ambient temperatures remained steady, this would lead to greater melting due to the reflectivity change. Air temperatures at most Canadian arctic weather stations have shown a general rise of 1 to 3 Celsius degrees when one compares 1971-2000 to earlier periods. There has been a general check in this rising curve since 1999 and a slight decrease is evident most recently. While some cite these rises as "indisputable" evidence of global warming (and remember, even if so, that does not prove a link to the greenhouse gases, it could be natural variations at work), I am not so convinced that it has a vast significance at all. The winter mean temperatures in the Canadian arctic remain in the -30 range © and it is hardly a catastrophic or runaway warming that we are seeing. It would take a whole century of warming similar to that observed in 1971-2000 to produce substantial change in the arctic environment. However, the rate of sea ice melting is not only dependent on local ambient temperature, but also ocean current changes in other regions, this matter of sooty deposition I just mentioned, and changes in precipitation or wind parameters. I think it is a form of tunnel vision to look at climate variation as either warming or not warming. The future may be complex and there is no reason why the 21st century might not see several different periods with identifiable differences. The past was generally like that, so why not the future as well?

I was just reviewing the maps for Monday-Tuesday of next week. Looks like western South Dakota might be the place to be for good storm chasing. Sometimes when you get the unstable weather and the lows as far north as southern Canada, the cold fronts are only active to about the SD-NE border and a strong cap holds back activity in Nebraska at least until well after sunset in some cases. Southwest SD is pretty wide open "badlands" country with great scenery in general, F3 tornado activity and large hail being quite common in the southern half of the state. There is a zone in western SD related to the Missouri escarpment where storm development often accelerates in mid-afternoon. I'll post some thoughts on severe weather locations as the tour gets under way. It seems that the active zone is shifting north next week but chances are it will return to the Kansas-Oklahoma area later in the week.

I'll bet you guys are getting excited now. Here's the latest map, as you can see, plenty of warm air over TX and OK, not much activity in terms of thunderstorms yet. I got rather busy with some other things and let that "daily severe weather" thread go for the past week, partly because there hasn't been a lot of active weather, at least no major outbreaks. As I was saying there, the period 30 April to 2 May should see a high peak of activity, so don't let the jet lag get to you. You're going the right way, of course, it's always worse travelling east than west. Here's the current map. This link should update every hour so my comments above apply to 23z of 23 April. << http://www.weatherimages.org/data/imag21.html >>