The Storm Prediction Center has indicated there is an enhanced risk of severe weather on Wednesday for the eastern Texas Panhandle, portions of Northwest Texas, and parts of Oklahoma where confidence is highest in several supercell thunderstorms. The enhanced risk zone includes Perryton, Canadian, Pampa, Shamrock, Childress, and Vernon. Surrounding the enhanced risk is a zone of possible severe weather where we expect a few supercells but confidence is lower than in the enhanced risk zone. Dumas, Amarillo, Plainview, Lubbock, Spur, Lamesa, Big Spring, Sweetwater, Abilene, Seymour, and Wichita Falls are a few towns included in this risk zone. A low risk of severe weather surrounds the possible risk zone where an isolated severe storm is possible.
The weak cold front responsible for Monday’s thunderstorms will continue to push south today. To the north of this boundary dewpoints (a measure of moisture) will drop off considerably. By Wednesday morning the richer moisture will begin to move back north along and ahead of a dryline on the western edge of the severe weather risk zone. Moisture levels will not be overly impressive by Wednesday evening which is the main reason we won’t be dealing with a tornado outbreak on Wednesday. Dewpoint values are anticipated to be in the 52 to 58 degree range by Wednesday afternoon ahead of the dryline. Without going into a ton of detail with surface temperatures anticipated to be in the upper 70s to lower 80s the temperature/dewpoint difference will be around 20 degrees. The result will be high-based thunderstorms (meaning they will be too high off the ground to pose much of a tornado threat) If dewpoint values were in the 62+ range we would be dealing with a major tornado outbreak due to lower cloud bases. Nevertheless wind shear is going to be very favorable for organized convection in the form of supercells. Instability values will also support severe weather. Even though cloud bases will be relatively high off the ground that does not mean the threat of supercells with very large hail and gusty winds will be mitigated. In fact, the visual storm structure on Wednesday will likely be awe inspiring and result in impressive photos from storm chasers who will be chasing on Wednesday (as we will be).
By 7 PM we should have supercell thunderstorms underway from the eastern Texas Panhandle/western Oklahoma ahead of the dryline all the way south into West-Central Texas. Storm coverage will be highest in the enhanced risk zone with fewer storms expected in the ‘possible’ risk zone. The primary threat from supercells on Wednesday will be the potential for destructive hail ranging from golfballs up to possibly even the size of softballs. That kind of hail is a threat to life and property. As the evening progresses a complex of thunderstorms may form from individual supercells and move east through the night towards the eastern end of the risk zone. Should that occur the cluster(s) will have the potential of producing hail up to the size of golfballs and straight-line winds in excess of 70 MPH. While high cloud bases will be a major mitigating factor for tornadoes I still don’t one to rule an isolated tornado out since wind shear will be quite favorable for storm rotation. The threat of destructive hail will be the biggest issue by far.
Here is the full outlook from the Storm Prediction Center including their meteorological discussion. If you’re not a weather nerd please feel free to ignore this as I’ve included it for the weather-weenies among the group.
SCATTERED SEVERE THUNDERSTORMS ARE EXPECTED TO DEVELOP WEDNESDAY
AFTERNOON ACROSS THE HIGH PLAINS FROM NORTHWEST TEXAS TO NORTHERN
NEBRASKA. LARGE HAIL AND DAMAGING WINDS CAN BE EXPECTED WITH THIS
…CENTRAL AND SOUTHERN PLAINS…
MULTIFACETED TROUGH WILL MIGRATE ACROSS THE ROCKIES WEDNESDAY WITH
PRIMARY CORRIDOR OF HEIGHT FALLS EXPECTED TO FOCUS OVER THE
NRN/CNTRL HIGH PLAINS THROUGH EARLY EVENING. HOWEVER…NAM
CONTINUES TO SUGGEST A LOW-AMPLITUDE SHORT-WAVE TROUGH WILL EJECT
FROM THE BASE OF THE PROGRESSIVE TROUGH ACROSS THE SRN HIGH PLAINS
INTO SWRN KS/TX PANHANDLE AFTER 21Z. 50KT+ 500MB SPEED MAX IS
FORECAST TO SPREAD ACROSS THE DRYLINE INTO NWRN OK BY 24/00Z
ENHANCING ENVIRONMENTAL SHEAR FOR SUSTAINING ORGANIZED ROTATING
LEE TROUGH WILL BE DISLODGED OFF THE HIGHER TERRAIN INTO WRN
KS…SWD INTO ERN TRANS PECOS OF TX AS STRONGER FLOW SPREADS ACROSS
THIS REGION…AIDED BY STRONG HEATING. WHILE ABSOLUTE MOISTURE
CONTENT IS NOT EXPECTED TO BE THAT GREAT…PW VALUES SHOULD RISE TO
AROUND ONE INCH JUST EAST OF THE DRYLINE WHERE SFC DEW POINTS HOLD
IN THE 50S. AS SFC TEMPERATURES WARM TO NEAR 80F SFC PARCELS SHOULD
FREELY CONVECT WITHIN A THERMODYNAMIC ENVIRONMENT CHARACTERIZED BY
ROUGHLY 1500-2000 J/KG SBCAPE. INITIALLY THIS ACTIVITY SHOULD BE
FAIRLY HIGH-BASED BUT LIKELY SUPERCELLULAR IN NATURE AS SUBSTANTIAL
SFC-6KM BULK SHEAR WILL EXIST ACROSS THIS REGION. LATEST THINKING
IS SCT SUPERCELLS…CAPABLE OF PRODUCING VERY LARGE HAIL…SHOULD
EMERGE DURING THE LATE AFTERNOON FROM THE ERN TX PANHANDLE…NWD
INTO WRN KS. SCT-NUMEROUS THUNDERSTORMS…WITH EMBEDDED
SUPERCELLS…ARE EXPECTED TO DEVELOP ALONG SURGING COLD FRONT ACROSS
NEB. THIS ACTIVITY MAY EVOLVE INTO A SQUALL LINE DURING THE EVENING
AS STRONG LLJ FOCUSES ACROSS ERN KS INTO SWRN IA.
EWD EXTENT OF THIS DIURNALLY INITIATED CONVECTION MAY ULTIMATELY
SPREAD TO NEAR I-35 CORRIDOR ACROSS OK/KS/NWRN MO/IA BY THE END OF