USA Weather, Inc.

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL HIGH PLAINS...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN WISCONSIN INTO NORTHERN ILLINOIS...AND EXTENDING FROM THE ARKLATEX INTO THE DEEP SOUTH...

...SUMMARY...
SEVERE THUNDERSTORMS PRODUCING VERY LARGE TO GIANT HAIL, A FEW TORNADOES, AND DAMAGING WINDS ARE LIKELY THIS AFTERNOON INTO TONIGHT ACROSS THE CENTRAL AND SOUTHERN HIGH PLAINS. HIGH-BASED, DRY THUNDERSTORMS ACROSS THE CENTRAL ROCKIES INTO THE GREAT BASIN WILL ALSO POSE A THREAT FOR SCATTERED DAMAGING WIND GUSTS. SEVERE THUNDERSTORMS MAY ALSO EVOLVE TODAY ACROSS PARTS OF THE UPPER MIDWEST AND OVER THE ARKLATEX INTO THE DEEP SOUTH.

...CENTRAL/SOUTHERN PLAINS...
A PERSISTENT UPPER RIDGE CENTERED OVER CENTRAL/SOUTHWESTERN TEXAS AND NORTHERN MEXICO WILL SLOWLY ERODE TODAY AS ZONAL FLOW EXTENDING ACROSS THE CENTRAL PLAINS INTENSIFIES SOME WITH THE PASSAGE OF AN EMBEDDED SHORTWAVE TROUGH. AT THE SURFACE, A STATIONARY FRONT REMAINS DRAPED FROM A WEAK SURFACE LOW OVER NORTH CENTRAL COLORADO SOUTHWEST INTO THE RED RIVER VALLEY. A LARGE AREA OF EXTENSIVE CONVECTION IS ONGOING NORTH OF THE FRONT ACROSS CENTRAL KANSAS AND OKLAHOMA, SPREADING SOUTHEAST WITH THE PROGRESSION OF AN ASSOCIATED MCV. THESE STORMS SHOULD LEAVE AN OUTFLOW BOUNDARY DRAPED ACROSS THE TEXAS PANHANDLE INTO NORTHEAST NEW MEXICO, WITH SUBSIDENCE AND EXTENSIVE CINH FURTHER NORTHEAST ACROSS THE CENTRAL GREAT PLAINS. EXTENSIVE LOW-LEVEL MOISTURE WITH MID 60S TO LOW 70S DEWPOINTS SHOULD EXTEND ACROSS THE SOUTHERN AND CENTRAL HIGH PLAINS BY LATE THIS AFTERNOON, PERHAPS AS FAR NORTH AS THE NEBRASKA PANHANDLE. LOWER DEWPOINTS ARE EXPECTED FURTHER WEST. ROBUST DIURNAL HEATING WELL INTO THE 80S BY THIS AFTERNOON COUPLED WITH IMPRESSIVE MID-LEVEL LAPSE RATES APPROACHING 9.0-9.5 C/KM SHOULD RESULT IN A BROAD CORRIDOR OF EXTENSIVE DESTABILIZATION WITH MLCAPE IN THE 2500-4000 J/KG THIS AFTERNOON AND EVENING ACROSS MUCH OF THE SOUTHERN/CENTRAL HIGH PLAINS. 

VARIOUS CAMS ARE IN GOOD AGREEMENT FOR CONVECTIVE INITIATION BY MID AFTERNOON INITIALLY ACROSS NORTH-CENTRAL COLORADO INTO CENTRAL WYOMING IN THE VICINITY OF THE AFOREMENTIONED STATIONARY FRONT, WHICH SHOULD BE LIFTING SLOWLY NORTHWARD BY THIS POINT IN TIME. THIS CONVECTION SHOULD INITIALLY BE HIGH-BASED DUE TO HIGHLY MIXED BOUNDARY LAYER CONDITIONS. OVERHEAD DEEP-LAYER SHEAR EXCEEDING 55KT WILL SUPPORT QUICK ORGANIZATION INTO SCATTERED SUPERCELLS AND A COUPLE STORM CLUSTERS. VERY LARGE TO GIANT HAIL ALONG WITH SCATTERED SEVERE WINDS SHOULD QUICKLY EVOLVE AS THE STORMS PROGRESS SOUTHEASTWARD. INCREASING COVERAGE BY EARLY EVENING IS EXPECTED AS SYNOPTIC FORCING FOR ASCENT INCREASES WITH THE SHORTWAVE MOVING OVERHEAD, ALONG WITH DEVELOPMENT SPREADING EAST INTO WESTERN NEBRASKA AND FAR SOUTHWEST SOUTH DAKOTA. HIGHER LOW-LEVEL MOISTURE IN THIS REGION ALONG WITH INTENSIFYING LOW-LEVEL JET WINDS SUPPORTIVE OF 200-300 M2/S2 SRH SHOULD SUPPORT AN INCREASING TORNADO THREAT WITH A CONTINUED SUPERCELL MODE, ALONG WITH DAMAGING HAIL AND SEVERE WINDS REMAINING LIKELY. CONTINUED SOUTHEASTWARD ADVANCEMENT IS EXPECTED THIS EVENING INTO TONIGHT, THOUGH FAIRLY SCATTERED COVERAGE APPEARS TO LIMIT UPSCALE GROWTH AT THIS TIME, THOUGH TRENDS WILL BE MONITORED.

A SECONDARY CORRIDOR OF SEVERE POTENTIAL WILL LIKELY EVOLVE THIS AFTERNOON AND EVENING ACROSS NORTHEAST NEW MEXICO INTO THE TEXAS PANHANDLE. AFOREMENTIONED SURGING OUTFLOW WILL EVENTUALLY SLOW AND POSSIBLY STALL BY LATE AFTERNOON WITHIN THIS AREA, PROVIDING A CONCENTRATED FOCUS FOR A FEW INTENSE SUPERCELLS TO DEVELOP AND SPREAD EAST. A VERY HOT AND UNSTABLE AIRMASS WITH MLCAPE OVER 3000 J/KG WILL BE NOTED IN THE VICINITY OF THIS OUTFLOW, WITH INTENSE DEEP-LAYER SHEAR IN EXCESS OF 45-55KT AND ELONGATED, CURVING HODOGRAPHS NOTED. THIS COULD BE SUPPORTIVE FOR AN INITIAL SUPERCELL MODE WITH VERY LARGE HAIL POTENTIAL POSSIBLY TRANSITIONING INTO A SWATH OF SIGNIFICANT WINDS SPREADING EASTWARD THIS EVENING. THERE IS VARYING MODEL SOLUTIONS IN THE EXACT PLACEMENT OF THE OUTFLOW AND THEREFORE THE CORRIDOR OF MORE SUBSTANTIAL SEVERE WINDS, ADDING SOME UNCERTAINTY TO THIS FORECAST, THUS PRECLUDING GREATER UNCONDITIONAL WIND PROBABILITIES AT THIS TIME. 

...CENTRAL ROCKIES INTO THE GREAT BASIN...
A SHORTWAVE MOVING NORTHEAST ACROSS CALIFORNIA WILL MOVE OVERTOP THE GREAT BASIN AND CENTRAL ROCKIES THIS AFTERNOON AND EVENING ALONG THE NORTHERN PERIPHERY OF THE RIDGE. A LARGE AREA OF SUBSTANTIAL HEATING OVERTOP IMPRESSIVE LAPSE RATES IS EXPECTED THIS AFTERNOON, WHICH WILL RESULT IN MODEST INSTABILITY. FURTHERMORE, A DEEPLY MIXED BOUNDARY LAYER INCLUDING DRY ADIABATIC LOW-LEVEL LAPSE RATES AND CLOUD BASES IN EXCESS OF 1 TO 2KM AGL CAN BE EXPECTED. THIS WILL RESULT IN SCATTERED HIGH-BASED, DRY THUNDERSTORMS SPREADING ACROSS THE REGION. ENHANCED MID TO UPPER LEVEL FLOW SUPPORTIVE OF 35-50KT DEEP-LAYER SHEAR WILL SUPPORT ORGANIZED LINE SEGMENTS FROM STRONGER STORMS, RESULTING IN THE EVOLUTION OF SCATTERED INTENSE OUTFLOW/DOWNBURST WINDS. POTENTIAL EXISTS FOR SPORADIC GUSTS IN EXCESS OF 75MPH DUE TO THE IMPRESSIVE MIXING EXPECTED.

...UPPER MIDWEST...
AN UPPER LEVEL LOW REMAINS CENTERED ACROSS NORTHERN MINNESOTA/NORTH DAKOTA, WITH A VERTICALLY STACKED CYCLONE ASSOCIATED WITH A SOUTHWARD-EXTENDING OCCLUDED FRONT. SIMILAR TO YESTERDAY, A PLUME OF RELATIVELY STEEP LOW LEVEL LAPSE RATES ALONG WITH FAVORABLE LOW-LEVEL MOISTURE AND HEATING WILL SUPPORT A BROAD CORRIDOR OF 1000-1500 J/KG MLCAPE THIS AFTERNOON ACROSS EASTERN MINNESOTA INTO WISCONSIN AND NORTHERN ILLINOIS. AN AXIS OF IMPRESSIVE 3CAPE OF 150-250 J/KG THIS AFTERNOON OVERTOP LENGTHY HODOGRAPHS AND AROUND 150 M2/S2 SRH SHOULD SUPPORT SCATTERED LOW-TOPPED SUPERCELLS TO DEVELOP AND SPREAD SOUTHEAST IN THE VICINITY OF THE OCCLUDED FRONT. A COUPLE TORNADOES AND LARGE HAIL, POTENTIALLY UP TO 2 INCHES IN DIAMETER, SHOULD BE THE PRIMARY CONCERNS TODAY, ALTHOUGH ISOLATED STRONG TO SEVERE WIND GUSTS MAY ALSO OCCUR.

...ARKLATEX INTO THE DEEP SOUTH...
TWO WELL-DEFINED MCVS ARE NOTED, ONE OVERTOP CENTRAL OKLAHOMA AND THE OTHER FURTHER EAST ACROSS CENTRAL MISSISSIPPI. BOTH OF THESE FEATURES WILL SLOWLY PUSH SOUTHEAST TODAY ON THE NORTHEAST PERIPHERY OF THE UPPER RIDGE. A WEAK STATIONARY FRONT DRAPED FROM THE ARKLATEX INTO THE WESTERN FLORIDA PANHANDLE WILL SERVE AS A CORRIDOR FOR CONVECTIVE DEVELOPMENT TODAY WITH NEARBY MCVS POSSIBLY ALLOWING BOTH FOR ENHANCED COVERAGE AND MARGINALLY FAVORABLE LOW-LEVEL SHEAR OF 25-30KT. A VERY HOT, MOIST AIRMASS SUPPORTIVE OF 3000-5000 J/KG MLCAPE TODAY, ALONG WITH MODERATE LAPSE RATES WILL SUPPORT RATHER INTENSE UPDRAFTS THIS AFTERNOON AND EVENING. WHILE THE WEAKER SHEAR VALUES MAY PRECLUDE ORGANIZATION SOMEWHAT, ISOLATED TO SCATTERED DAMAGING WINDS APPEAR TO BE A CONCERN PARTICULARLY IN THE VICINITY OF THE FRONT. SOME HIGH-RESOLUTION GUIDANCE HAS HINTED AT AN ATTEMPT FOR A MORE ORGANIZED MCS TO EVOLVE THIS AFTERNOON AND EVENING ACROSS THE REGION, WHICH WOULD SUPPORT A CORRIDOR OF GREATER WIND POTENTIAL. MODEST LOW-LEVEL HELICITY MAY ALSO SUPPORT A BRIEF TORNADO OR TWO IF ANY TRANSIENT MESOCYCLONES DEVELOP. A NARROW SLIGHT RISK HAS BEEN OUTLINED NEAR THE STATIONARY FRONT, WHERE VARIOUS MODELS SHOW HIGHER STORM COVERAGE, EVEN IF A MORE ORGANIZED MCS DOESN’T EVOLVE.

FURTHER NORTHWEST, SOMEWHAT STRONGER SHEAR IN THE 30-40KT RANGE MAY SUPPORT A COUPLE OF SUPERCELLS TODAY, MAINLY ACROSS CENTRAL INTO EASTERN OKLAHOMA. GIVEN THE IMPRESSIVE INSTABILITY, A HIGHER HAIL THREAT MAY ALSO EVOLVE HERE, INCLUDING AN INSTANCE OR TWO OF VERY LARGE HAIL.