USA Weather, Inc.

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL DAKOTAS...

...SUMMARY...
SEVERE THUNDERSTORMS PRODUCING NUMEROUS DAMAGING WINDS OF 60-85MPH, VERY LARGE HAIL, AND A COUPLE TORNADOES ARE LIKELY THIS AFTERNOON AND EVENING ACROSS THE NORTHERN PLAINS, ESPECIALLY OVER THE CENTRAL DAKOTAS INTO WESTERN NEBRASKA AND EASTERN WYOMING. ISOLATED TO SCATTERED SEVERE STORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE ALSO POSSIBLE ACROSS THE SOUTHERN AND CENTRAL HIGH PLAINS, ESPECIALLY OVER A PORTION OF SOUTHEAST COLORADO INTO SOUTHWEST KANSAS. FINALLY, NUMEROUS TO WIDESPREAD THUNDERSTORMS ACROSS THE SOUTHEAST COULD OCCASIONALLY PRODUCE BRIEFLY SEVERE WIND/HAIL.

...SYNOPSIS...
A FAIRLY COMPLEX MID TO UPPER LEVEL PATTERN IS NOTED ON MORNING WATER VAPOR IMAGERY, WITH  A WELL-DEFINED MID-LEVEL RIDGE AXIS EXTENDING NORTHWARD ACROSS THE SOUTHERN AND CENTRAL GREAT PLAINS. THE RIDGE AXIS WILL STRETCH TO THE NORTHEAST WITH TIME TODAY AS A LARGE UPPER TROUGH EXTENDING INTO THE NORTHEAST CONUS GRADUALLY SHIFTS SOUTHWARD TODAY, RESULTING IN THE SOUTH-SOUTHWESTERLY FLOW ON THE EAST OF A STALLED UPPER LOW ACROSS THE NORTHERN ROCKIES BECOMING MORE WEST-SOUTHWESTERLY ORIENTED TODAY, AS WELL AS THE DEVELOPMENT OF A 50-60KT MID-LEVEL JET MAX ACROSS THIS AREA.

AT THE SURFACE, A VERTICALLY STACKED OCCLUDED LOW OVER NORTHERN MONTANA WILL SLOWLY SHIFT NORTHWARD, WITH THE OCCLUDED FRONT AND TRAILING COLD FRONT QUICKLY SPREADING NORTHEAST, MOVING ACROSS THE NORTHERN PLAINS AND DAKOTAS THIS AFTERNOON INTO TONIGHT. IN ADDITION, A COLD FRONT EXTENDING ACROSS THE WESTERN ATLANTIC INTO THE SOUTHERN APPALACHIANS INTO THE ARKLATEX THIS MORNING WILL SPREAD SOUTHWARD TODAY WITH THE APPROACH OF THE UPPER TROUGH AXIS. THIS COLD FRONT WILL MOVE INTO THE NORTHERN GULF THIS EVENING OR TONIGHT.

...NORTHERN PLAINS/DAKOTAS...
ISOLATED HIGH-BASED CONVECTION IS ONGOING THIS MORNING OVER THE FAR WESTERN DAKOTAS IN ASSOCIATION WITH SUBTLE VORTICITY OVERSPREADING THIS AREA. THIS CONVECTION WILL GRADUALLY SPREAD NORTHEAST, LEAVING A BROAD AREA OF MODERATE TO STRONG SURFACE HEATING IN ITS WAKE, SPREADING INTO THE CENTRAL DAKOTAS AND WESTERN NEBRASKA BY THIS AFTERNOON. WITH AFTERNOON TEMPERATURES IN THE 80S WITHIN UPPER 50S TO MID-60S DEWPOINTS AND LAPSE RATES >8.0 J/KG, A BROAD AREA OF FAIRLY ROBUST DESTABILIZATION SHOULD OCCUR THIS AFTERNOON WITH MLCAPE INCREASING INTO THE 2000-3000 J/KG RANGE, ESPECIALLY ACROSS CENTRAL AND WESTERN SOUTH DAKOTA INTO PARTS OF NORTH DAKOTA. 

IN RESPONSE TO INCREASED FORCING FOR ASCENT AND STRENGTHENING BUOYANCY, INITIALLY ISOLATED INTENSE CONVECTIVE DEVELOPMENT IN THE VICINITY OF WHERE ONGOING SHOWERS SHOULD OCCUR BY EARLY AFTERNOON, WITH COVERAGE INCREASING DURING THE FOLLOWING HOURS AS WELL AS DEVELOPMENT OCCURRING ACROSS PARTS OF THE NORTHERN HIGH PLAINS AS WELL. FAIRLY STRONG DEEP-LAYER SHEAR WITH ELONGATED HODOGRAPHS WILL SUPPORT AN INITIAL MIXED SUPERCELL AND STORM CLUSTER MODE, WITH ALL SEVERE HAZARDS, INCLUDING A COUPLE TORNADOES, WILL BE PROBABLE. GRADUAL CONSOLIDATION INTO A LARGE MCS SHOULD OCCUR DURING THE LATE AFTERNOON HOURS AS COVERAGE INCREASES, RESULTING IN AN INCREASINGLY NUMEROUS DAMAGING WIND THREAT WITH EMBEDDED SWATHS OF 75+ MPH WINDS LIKELY ESPECIALLY WHERE SURGING OUTFLOW BOUNDARIES AND BOWING SEGMENTS DEVELOP. THIS COMPLEX WILL SPREAD NORTHEASTWARD DURING THE EVENING HOURS BEFORE GRADUALLY WEAKENING OVERNIGHT.

...CENTRAL AND SOUTHERN PLAINS...
A DECAYING MCS ACROSS THE CENTRAL GREAT PLAINS HAS RESULTED IN A LARGE AREA OF SUBSIDENCE AND CLOUD COVER COINCIDING WITH THE MID-LEVEL RIDGE AXIS, YIELDING UNFAVORABLE THERMODYNAMICS THIS MORNING. HOWEVER, A NOTABLE MOISTURE SURGE WITH DEWPOINTS IN THE 50S EXTENDS ACROSS THE SOUTHERN AND CENTRAL HIGH PLAINS ON THE WESTERN PERIPHERY OF THIS DECAYED COMPLEX. WITH HOT TEMPERATURES, VERY STEEP MID-LEVEL LAPSE RATES, AND A DEEPLY MIXED BOUNDARY LAYER EXPECTED TO EVOLVE THIS AFTERNOON OVER THE HIGH PLAINS, DEVELOPMENT OF MLCAPE IN THE 1000-2000 J/KG RANGE CAN BE EXPECTED, PERHAPS WITH AREAS ACROSS SOUTHEAST COLORADO INTO SOUTHWEST KANSAS WITH HIGHER INSTABILITY GIVEN LOCALLY HIGHER MOISTURE. ISOLATED TO SCATTERED HIGH-BASED CONVECTION SHOULD INITIALLY DEVELOP OFF OF THE HIGHER TERRAIN SPREADING EASTWARD DURING THE AFTERNOON HOURS. MODERATE DEEP-LAYER SHEAR WILL SUPPORT SCATTERED ORGANIZED LINE SEGMENTS AND SUPERCELLS WITH A SEVERE WIND/HAIL THREAT IN ANY STRONGER CONVECTION EXPECTED. A RELATIVELY HIGHER CONCENTRATION OF SEVERE WIND IS EXPECTED ACROSS AFOREMENTIONED PARTS OF CO/KS GIVEN GREATER INSTABILITY, ESPECIALLY IF A MORE ORGANIZED MCS CAN DEVELOP AS HAS BEEN SUGGESTED BY MULTIPLE CAMS THIS MORNING. A SECONDARY SLIGHT RISK HAS BEEN INTRODUCED FOR THIS AREA AS A RESULT.

...SOUTHEAST/GULF COAST...
A VERY MOIST AIRMASS AHEAD OF THE SOUTHWARD ADVANCING COLD FRONT WITH DEWPOINTS IN THE MID TO UPPER 70S WILL HEAT WELL INTO THE 90S TO NEAR 100 IN A FEW SPOTS OVER EAST TEXAS WILL RESULT IN STRONG INSTABILITY, WITH 3000-5000 J/KG MLCAPE THIS AFTERNOON. WIDESPREAD THUNDERSTORMS WILL DEVELOP BY THIS AFTERNOON ALONG AND AHEAD OF THE COLD FRONT, ALONG THE SEABREEZE, AND REMNANT OUTFLOW BOTH FROM YESTERDAY’S STORMS AND FROM TODAY’S STORMS. DESPITE MODEST SHEAR OF 20-25KT AT BEST, THE HIGHLY UNSTABLE AIRMASS AND THE WIDESPREAD COVERAGE SHOULD SUPPORT A LARGE AREA WITH POTENTIAL FOR SPORADIC STRONG TO SEVERE WINDS DUE TO WATER-LOADED MICROBURSTS. A FEW BRIEF INSTANCES OF MARGINALLY SEVERE HAIL MAY ALSO EVOLVE OVER WESTERN PARTS OF THE MRGL RISK AREA GIVEN EXPECTED TALL UPDRAFTS.

SOME POTENTIAL MAY ALSO EVOLVE FOR A LOOSELY ORGANIZING LINEAR COMPLEX TO EVOLVE ALONG CONGLOMERATE OUTFLOW BOUNDARIES THIS AFTERNOON, PARTICULARLY FROM EAST TEXAS INTO SOUTHERN MISSISSIPPI WHERE THE GREATEST SURFACE HEATING OCCURS. SHOULD THIS OCCUR, A CORRIDOR OF GREATER WIND DAMAGE POTENTIAL MAY EVOLVE.