Overview

May 18, 2013 | 9:10 AM CDT - The most significant round of Severe Weather the Plains has seen this season begins this afternoon and lasts through at least Monday. The latest water vapor imagery from NEXLAB shows our weather-maker pushing into the Eastern Rockies. What will trigger the round of Severe Weather over the next several days are embedded disturbances and shortwaves rotating around the broad low pressure system. This is what makes the timing and evolution of the outbreak a bit uncertain.

8:45 AM Water Vapor Imagery – May 18, 2013

Today’s threat will reside from West Central and western North Texas through Western/North Central Oklahoma and most of Kansas. The greatest potential for Severe Weather will be across Western Oklahoma and West Central Kansas into Southwest Nebraska. Forecast soundings by late afternoon and, especially, early evening show a very favorable environment that would support a couple Strong Tornadoes. Similar to yesterday across North Texas, LCLs (cloud bases) will be fairly high for Tornadoes, but high instability will compensate. A dangerous situation will unfold across the Moderate Risk area later today, so this area needs to be especially on guard.

1300z SPC Day 1 Outlook – Valid Today/Tonight

Farther south across Texas, a stronger cap will exist and flow will be weaker. Still, with intense surface heating today, the cap will likely erode mid to late this afternoon, allowing for isolated to widely scattered storms off the dryline. With stronger flow than yesterday, storms WILL move unlike yesterday. Mean storm motion should be toward the E/NE, but any rotating Supercell would likely be a right-mover, having a more easterly/southeasterly component. As convection runs into an increasing cap across North Texas this evening, it will likely dissipate. This is expected to keep people near and east of the I-35 corridor dry this evening.

12z RAP Model Forecast Reflectivity At 5:00 PM

The overall Severe/Tornado Threat will decrease after 10:00 PM, but at least a low threat will linger into the early morning hours Sunday. The focus for Severe Weather will shift eastward Sunday, centering across Central and Northeast Oklahoma with a more isolated threat into North Texas. The Dallas-Ft. Worth metroplex may be impacted by Severe Weather tomorrow evening, so be sure to stay tuned to the latest forecasts. This is still a developing situation, so expect additional tweaks to the forecast over the next couple of days. You can follow ConvectiveWeather on Facebook and Twitter for the latest updates!

0600z SPC Day 2 Outlook – Valid May 19, 2013

Severe Threat Increasing

May 8, 2013 | 3:30 PM CDT - Widely scattered storms have begun to develop across parts of Northwest Texas and Western Oklahoma this afternoon. This has prompted a Severe T-Storm Watch from the NWS for parts of NW TX…W OK…& SC KS. The environment is moderately to highly unstable with pockets of SBCAPE as great as 3,500 j/kg across the watch area. Both low-level and mid-level lapse rates are fairly steep and Lifted Indices are high, generally from -6 to -10. The limiting factors for a more robust event are less-than-favorable upper-level winds and 0-6 km Bulk Shear.

3:25 PM Visible Satellite – May 8, 2013

Very Large Hail to the size of Baseballs and Damaging Winds in excess of 65 mph will be the primary hazards with any Severe Storm this afternoon and evening. A brief Tornado or two is also possible. Below are the details from the SPC. Remember, Severe Weather can occur with little or no advance warning. -Stay Tuned!

Severe Thunderstorm Watch 149

 SEL9

   URGENT - IMMEDIATE BROADCAST REQUESTED
   SEVERE THUNDERSTORM WATCH NUMBER 149
   NWS STORM PREDICTION CENTER NORMAN OK
   320 PM CDT WED MAY 8 2013

   THE NWS STORM PREDICTION CENTER HAS ISSUED A

   * SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 
     WESTERN AND CENTRAL KANSAS
     WESTERN AND CENTRAL OKLAHOMA
     WEST CENTRAL AND NORTHWEST TEXAS AND EASTERN PARTS OF THE TEXAS
   PANHANDLE

   * EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 320 PM
     UNTIL 1100 PM CDT.

   * PRIMARY THREATS INCLUDE...
     NUMEROUS LARGE HAIL EVENTS EXPECTED WITH SEVERAL VERY LARGE HAIL
       EVENTS TO 3 INCHES IN DIAMETER POSSIBLE
     SEVERAL DAMAGING WIND GUSTS TO 70 MPH LIKELY
     A FEW TORNADOES POSSIBLE

   THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 75
   STATUTE MILES EAST AND WEST OF A LINE FROM 100 MILES SOUTH
   SOUTHEAST OF CHILDRESS TEXAS TO 20 MILES NORTH NORTHEAST OF
   RUSSELL KANSAS.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
   ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU9).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
   FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
   AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
   THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
   AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
   DO PRODUCE TORNADOES.

   &&

   OTHER WATCH INFORMATION...CONTINUE...WW 148...

   DISCUSSION...SCTD SUSTAINED TSTMS/SUPERCELLS EXPECTED TO FORM ALONG
   AND AHEAD OF DRY LINE/LEE TROUGH EXTENDING SSW FROM SW KS SFC LOW
   INTO WRN TX. STRENGTH AND DISCRETE NATURE OF STORMS WILL BE AIDED BY
   RELATIVELY MODEST LOW-LVL CONVERGENCE...PERSISTENT UPR
   DIFFLUENCE...AND STEEP LOW TO MID-LVL LAPSE RATES...SUGGESTING A
   RISK FOR BOTH LARGE HAIL AND LOCALLY DMGG WINDS. WHILE
   TEMPERATURE-DEWPOINT SPREADS ARE SIZABLE IN WW ATTM...POTENTIAL WILL
   EXIST FOR CORRIDORS WITH AN ENHANCED RISK FOR LOW-LVL
   ROTATION/TORNADOES GIVEN EXPECTED STORM INTERACTIONS LATER THIS
   EVE..AND AS BOUNDARY LAYER BEGINS TO COOL/SSWLY LLJ STRENGTHENS.
   THUS...PARTS OF THE WW MAY REQUIRE POSSIBLE UPGRADE TO TORNADO WW
   LATER THIS EVE.

   AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
   TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
   KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
   MOTION VECTOR 25025.

   ...CORFIDI

*Emphasis Added*

An Eye To the Sky…

May 8, 2013 | 12:50 PM CDT - Yesterday, we saw some Severe Storms, mainly Hailers, across the High Plains. Today, a similar situation will unfold. The Severe Threat this afternoon and evening will be greater than yesterday with more moisture available. The hi-res models are consistent in initiating storms off the dryline between 3:00 and 5:00 PM. Early activity will pose the greatest threat for Very Large Hail to the size of Baseballs. In addition to the Large Hail threat, Damaging Winds will be likely with any Severe Storm this afternoon and evening. Fairly high LCLs (cloud bases) and the lack of more favorable upper-level winds should limit the Tornado Threat. With that said, a brief Tornado or two is possible.

1630z SPC Day 1 Outlook – Valid Today/Tonight

By mid to late evening, storms will become elevated but will still be capable of Quarter-size Hail and Damaging Winds. Storm mergers this evening will likely result in another cluster or two, similar to what was seen in West Central Texas last night. Today’s and tonight’s convection will have some impact on tomorrow’s Severe Weather Threat.

Be sure to keep an eye to the sky later today. Although widespread Severe Weather is not anticipated, a few storms could become locally intense with Destructive Hail to the size of Baseballs, Damaging Winds in excess of 65 mph, and perhaps a Tornado. -Stay Tuned!

Today’s Severe Threat – NWS In Norman, OK

Slight Risk

May 7, 2013 | 10:20 AM CDT - Strong to Severe Storms will take aim at the Southern High Plains of Texas, Oklahoma, and Kansas today and tomorrow. While the main upper-low will reside well to the west of the region, embedded disturbances and strong surface heating appear to be enough to break the cap near the dryline. Upper-level winds and deep layer shear are not especially favorable for organized Severe Weather, so despite favorable instability and high Lifted Indices, Severe Storms are likely to occur on a more isolated basis. This is especially the case today, as dew points will only be in the upper-40*F’s to low 50*F’s – marginal for Severe Weather. Large Hail to the size of Golf Balls and Damaging Winds in excess of 60 mph will be the primary threats this afternoon and evening. The Tornado threat will be very low due to (1) less than favorable moisture, (2) fairly high cloud bases, and (3) the lack of more favorable upper-level winds.

1300z SPC Day 1 Outlook – Valid Today/Tonight

Wednesday looks to be more favorable for Severe Weather as dew points rise into the upper-50*F’s to low-60*F’s across the risk area. Widely scattered storms will likely develop off the dryline draped from West Central/Northwest Texas into Southwest Kansas. Hail stones the size of Golf Balls, or larger, and Damaging Winds will once again be the primary hazards late tomorrow afternoon and evening. With more moisture available, a brief Tornado will be possible late tomorrow, but Hail and Wind will be the biggest threats.

0600z SPC Day 1 Outlook – Valid May 8, 2013

If an organized cold pool can result from evening storm mergers, then some of this activity could persist into the overnight hours. The development of any outflow boundaries and/or differential heating areas will have an impact on Thursday’s Severe Weather Threat across North Central Texas and Central Oklahoma. This will be monitored…

0730z SPC Day 3 Outlook – Valid May 9, 2013