



I’m sure I can speak for just about every Texan when I say that I’m beyond glad that 2011 has passed. What a historic year for not only us, but other parts of the United States as well. Below is the 2011 State of the Climate summary released today from NOAA’s National Climatic Data Center. Here’s to hoping we never have another year like it…
This graphic shows the surface dewpoint values at 5 PM. Simply put, Dewpoints are a measure of moisture. I’m expecting the highest severe weather threat to be along and south of a northward moving warm front. At 5 PM, that warm front was just north of San Antonio, where you can see the 60° dewpoint line. This warm front will continue to lift slowly northward, bringing the higher moisture amounts with it.
This is one of our high resolution model outputs. This comes from the High Resolution Rapid Refresh. It’s indicating a squall line just west of the Interstate 35 corridor by about 1 AM. As expected, the stronger storms are down by San Antonio and Austin. However, storms that form out ahead of the squall line will have to be watched for rotation, especially south of Waco. Simply put, we could have a few severe thunderstorms overnight. This is not expected to be a major severe weather outbreak, but some large hail and straight line winds are possible, especially in the squall line. We cannot rule a a brief tornado or two because of the very favorable wind fields. Instability is lacking, otherwise this would be a major tornado outbreak. Just stay tuned tonight and have a way to get weather warnings overnight. The iMap Weather Radio is a great tool for iPhones. ABC News just aired a story this app and it works. We highly recommend it! We’ll likely go out chasing after about 9 PM and will have our live video up then. Stay tuned to our facebook and twitter pages!
MESOSCALE DISCUSSION 2379 NWS STORM PREDICTION CENTER NORMAN OK 0258 PM CST MON DEC 19 2011 AREAS AFFECTED...CNTRL TX CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 192058Z - 192300Z A CONDITIONAL THREAT OF SEVERE THUNDERSTORMS IS GRADUALLY INCREASING ACROSS PORTIONS OF CNTRL TO E CNTRL TX...AND TRENDS WILL CONTINUE TO BE MONITORED FOR A POSSIBLE WATCH LATER TODAY. RADAR CONTINUES TO SHOW A N/S BAND OF SHALLOW CONVECTIVE SHOWER FROM WRN OK INTO TX...JUST W OF THE I-35 CORRIDOR. NO LIGHTNING HAS BEEN OBSERVED WITH THIS ACTIVITY DUE TO RELATIVELY POOR LOW LEVEL LAPSE RATES PROFILES. THE 20 Z FWD SOUNDING DID INDICATE ELEVATED CAPE ON THE ORDER OF 600 J/KG WITH A LARGE HODOGRAPH...ALTHOUGH MUCH OF THE LOWER PORTION IS BEING MADE INEFFECTIVE DUE TO A RELATIVELY STABLE BOUNDARY LAYER THIS FAR N. TO THE S...A NARROW AXIS OF LOW TO MID 60S F DEWPOINTS AS WELL AS WARMER SURFACE TEMPERATURES EXISTED FROM THE CNTRL TX COAST TOWARD AUSTIN. HERE...RADAR HAS SHOWN SOME INCREASE IN REFLECTIVITIES ASSOCIATED WITH SLOWLY GROWING WARM SECTOR CONVECTION. A LIGHTNING STRIKE WAS RECENTLY NOTED WITH ACTIVITY S OF FT. WORTH. CONTINUED FORCING ALONG THE COLD FRONT...AS WELL AS SOME FURTHER DESTABILIZATION...MAY EVENTUALLY RESULT IN A FEW STRONG TO SEVERE THUNDERSTORMS LATER TODAY. ALTHOUGH CELLS MAY FORM IN A LINEAR FASHION ALONG THE FRONT...SHEAR PROFILES WILL FAVOR AN EVOLUTION INTO SUPERCELLS...POSSIBLY IN A MERGED LINE...AND AN ISOLATED TORNADO MAY OCCUR GIVEN SUCH STRONG LOW LEVEL SHEAR. ANY SUPERCELL WILL ALSO BE CAPABLE OF HAIL AND LOCALLY DAMAGING WIND GUSTS. ONE NEGATIVE FOR COVERAGE OF SEVERE WILL BE RELATIVELY MERIDIONAL STORM MOTIONS WHICH WILL TEND TO MOVE THE STORMS AWAY FROM THE BETTER INSTABILITY. ..JEWELL.. 12/19/2011 ATTN...WFO...SHV...HGX...FWD...EWX...
The above three graphics show the potential of a specific hazard within 25 miles of any given location. I’ve included the chance of a tornado, large hail, and damaging winds. A standard risk of severe weather remains in effect for a large portion of Central Texas this afternoon an evening. With the new severe weather outlook just issued by the Storm Prediction Center, the standard risk line of severe weather was extended northward to include most of North Texas, including the D/FW metroplex. In comparison to this morning’s 12 AM outlook, SPC have increased the tornado probabilities across North and Central Texas. Today’s primary severe weather threat will be damaging wind, but a few tornadoes cannot be ruled out. I’m just about to go pack up the chase car and head south out of Dallas. My inital plan is to head towards Waco on I-35 and wait for storms to initate, at which point It’ll be a race to keep up with the storms.
Since today’s storms will be moving at 50-60 MPH, it’s important to take immediate action when a warning is issued for your area since the lead time may be reduced. Once we’re out chasing, we won’t be able to post constant updates on the evolving weather situation, so be sure to follow your local media outlets and National Weather Service office. Once we’re on the road, we’ll start our live video stream. We’ll publish a new post on here, along with a facebook and twitter notification when that happens. We’ll be streaming at www.texasstormchasers.com/live
Have a good Monday and stay safe!
Here’s the new severe weather outlook from the Storm Prediction Center. Severe weather probabilities have been maintained from the previous outlook. It should be noted that these values could be adjusted higher in later outlooks by the Storm Prediction Center once the details of today’s event becomes clearer. Here’s the full outlook.
...CNTRL AND EAST TX... AN UPPER-LEVEL LOW IN SE AZ WILL MOVE QUICKLY EAST TO NEWD ACROSS WEST TX TODAY. TO THE EAST OF THE SYSTEM...A 45 TO 60 KT LOW-LEVEL JET WILL STRENGTHEN...RAPIDLY TRANSPORTING MOISTURE NWD INTO CNTRL TX THIS AFTERNOON. SFC-BASED THUNDERSTORM DEVELOPMENT IS FORECAST THIS AFTERNOON ALONG THE WRN EDGE OF THE MOIST AXIS WHERE A LINE OF THUNDERSTORMS IS LIKELY TO ORGANIZE AND MOVE EWD ACROSS THE I-35 CORRIDOR FROM NEAR DALLAS/FORTH WORTH SWD TO NEAR BRIAN-COLLEGE STATION. THIS LINE SHOULD PERSIST EWD ACROSS THE SLIGHT RISK AREA EVENTUALLY AFFECTING THE HOUSTON AREA DURING THE EVENING. AS THE UPPER-LEVEL LOW MOVES OUT INTO THE SRN PLAINS...A 65 TO 80 KT MID-LEVEL JET IN THE BASE OF THE TROUGH WILL CREATE STRONG DEEP LAYER SHEAR PROFILES ACROSS THE SLIGHT RISK AREA. FORECAST SOUNDINGS ALONG THE I-35 CORRIDOR AT 00Z SHOW 0-6 KM SHEAR VALUES IN THE 55 TO 65 KT RANGE. IN ADDITION...SFC DEWPOINTS MAY REACH THE LOWER 60S F AS FAR NORTH AS DALLAS WITH UPPER 60S F LOCATED ALONG THE MIDDLE TX COAST WHERE MODERATE INSTABILITY IS FORECAST. THIS ENVIRONMENT SHOULD SUPPORT SEVERE STORMS WITH THE GREATEST POTENTIAL ACROSS THE NRN HALF OF THE SLIGHT RISK AREA WHERE THUNDERSTORM DEVELOPMENT IS MOST CERTAIN. AS THUNDERSTORMS INITIATE...SUPERCELL DEVELOPMENT WILL BE POSSIBLE ACROSS THE WRN PART OF THE SLIGHT RISK AREA WHILE THE CONVECTION REMAINS DISCRETE. AS STORMS INCREASE IN COVERAGE AND A LINE ORGANIZES...A WIND DAMAGE THREAT MAY DEVELOP WITH THE GREATEST POTENTIAL ACROSS THE CNTRL AND ERN PART OF THE SLIGHT RISK AREA. THE MAGNITUDE OF THE SEVERE THREAT SHOULD DEPEND ON UPON HOW MUCH DESTABILIZATION TAKES PLACE IN CNTRL AND EAST TX THIS AFTERNOON. ALTHOUGH THE SRN END OF THE LINE SHOULD AFFECT THE HOUSTON AREA THIS EVENING...LARGE-SCALE ASCENT WILL BE QUITE WEAK IN SE TX SUGGESTING THE SEVERE THREAT COULD BE MORE ISOLATED THERE. ...NW TX/SW OK... SCATTERED THUNDERSTORMS SHOULD BE ONGOING ACROSS WEST AND NORTHWEST TX AT DAYBREAK. THIS ACTIVITY SHOULD BE FOCUSED ALONG THE NWRN EDGE OF THE LOW-LEVEL JET AND ALONG THE LEADING EDGE OF LARGE-SCALE ASCENT ASSOCIATED WITH AN APPROACHING UPPER-LEVEL LOW. FORECAST SOUNDINGS ACROSS WEST AND NORTHWEST TX THIS MORNING SHOW SOME CAPE IN THE 700 TO 500 MB LAYER WITH INSTABILITY INCREASING AS THE AIRMASS WARMS THIS AFTERNOON. THIS ALONG WITH STEEP MID-LEVEL LAPSE RATES SHOULD BE ENOUGH FOR AN ISOLATED HAIL THREAT AS CONVECTION INITIATES JUST AHEAD OF THE UPPER-LEVEL LOW. THE HAIL THREAT APPEARS MOST LIKELY TO AFFECT NW TX AND SW OK AS STORMS MOVE NEWD ACROSS THE REGION LATE THIS AFTERNOON. THE POTENTIAL FOR HAIL IS EXPECTED TO REMAIN MARGINAL WITH A 5 PERCENT HAIL PROBABILITY SUFFICIENT TO COVER THE THREAT.