Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point.
Tornado Risk
Area (sq. mi.)
Area Pop.
Some Larger Population Centers in Risk Area
2 %
7,226
131,995
Cheyenne, WY...Laramie, WY...
Probabilistic Damaging Wind Graphic
Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point.
SPC AC 281958
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0258 PM CDT SUN SEP 28 2014
VALID 282000Z - 291200Z
...NO SVR TSTM AREAS FORECAST...
...SUMMARY...
A FEW STRONG TO MARGINALLY SEVERE THUNDERSTORMS ARE POSSIBLE THIS
AFTERNOON INTO EVENING OVER PARTS OF THE CENTRAL HIGH PLAINS AND
FOUR CORNERS REGION.
...FOUR CORNERS REGION INTO THE CENTRAL HIGH PLAINS...
ONLY VERY MINOR ADJUSTMENTS TO THE PROBABILITY AND THUNDER LINES
HAVE BEEN MADE IN THIS UPDATE AND THE FORECAST RATIONALE REMAINS
LARGELY UNCHANGED. MODEST DESTABILIZATION IS UNDERWAY ACROSS THE
FOUR CORNERS REGION AND ALSO ACROSS SERN WY/NERN CO...WHICH WILL AID
IN AN INTENSIFICATION OF CONVECTION ACROSS THESE AREAS LATER THIS
AFTERNOON INTO THIS EVENING. SUFFICIENT DEEP-LAYER SHEAR FOR AT
LEAST MARGINALLY ORGANIZED STORMS WILL SUPPORT AN ISOLATED DAMAGING
WIND/LARGE HAIL RISK INTO THE EVENING.
..DEAN/PETERS.. 09/28/2014
.PREV DISCUSSION... /ISSUED 1119 AM CDT SUN SEP 28 2014/
...SYNOPSIS...
A MID TO UPPER-LEVEL LOW OVER NV WILL CONTINUE TO EDGE EWD ACROSS
THE GREAT BASIN IN RESPONSE TO THE APPROACH OF AN UPSTREAM TROUGH
OVER THE FAR NERN PACIFIC. SEVERAL VORTICITY MAXIMA WILL PIVOT
AROUND THE GREAT BASIN UPPER LOW...ONE OF WHICH WILL PROGRESS FROM
THE FOUR CORNERS REGION INTO WRN WY BY LATE AFTERNOON/EARLY
EVENING.
AT THE SURFACE...A LEE CYCLONE WILL DEEPEN OVER NERN CO
TODAY...ALLOWING A COLD FRONT TO BECOME QUASI-STATIONARY OVER THE
CNTRL HIGH PLAINS. FARTHER TO THE NE...A STRENGTHENING ANTICYCLONE
OVER CNTRL CANADA WILL PROMOTE THE SWD MOVEMENT OF THE SAME COLD
FRONT OVER THE NRN PLAINS INTO UPPER GREAT LAKES.
...SERN WY/NERN CO/WRN NEB PNHDL THIS AFTERNOON/EVENING...
THE LOW-LEVEL MASS RESPONSE TO THE HIGH PLAINS CYCLOGENESIS WILL
ENHANCE THE NWWD FLUX OF AN INCREASINGLY MOIST BOUNDARY LAYER
BENEATH A PLUME OF MODESTLY STEEP MID-LEVEL LAPSE RATES...YIELDING
AFTERNOON MLCAPE OF 500-750 J/KG IN AREAS WHICH EXPERIENCE STRONGER
DAYTIME HEATING. A LOW-LEVEL CONVERGENT AND UPSLOPE FLOW REGIME
INVOF THE LEE CYCLONE AND ATTENDANT FRONT COUPLED WITH THE GLANCING
INFLUENCE OF THE MIGRATORY VORTICITY MAXIMUM MENTIONED ABOVE ARE
EXPECTED TO FOSTER ISOLATED TO WIDELY SCATTERED TSTM DEVELOPMENT
LATER THIS AFTERNOON INTO EVENING.
WHILE DEEP-LAYER SHEAR MAGNITUDES WILL BE ON THE MARGINS /I.E. 30
KT/ OF THAT WHICH SUPPORTS STORM ORGANIZATION...PRONOUNCED VEERING
OF LOWER-TROPOSPHERIC WINDS WITH HEIGHT MAY ENCOURAGE SOME UPDRAFT
ROTATION AND A RISK FOR HAIL...GUSTY WINDS...AND PERHAPS A BRIEF
TORNADO.
...FOUR CORNERS REGION THIS AFTERNOON/EVENING...
IN THE WAKE OF THE DEPARTING CLOUD SHIELD ASSOCIATED WITH THE WARM
CONVEYOR AIR STREAM...STEEPENING LAPSE RATES SHOULD PROMOTE AT LEAST
MARGINAL INSTABILITY LATER TODAY. OROGRAPHIC FORCING IN TANDEM WITH
THE INFLUENCE OF AN UPSTREAM VORTICITY LOBE OVERSPREADING THE REGION
MAY SUPPORT ISOLATED TO WIDELY SCATTERED STORM DEVELOPMENT THIS
AFTERNOON. GIVEN THE PRESENCE OF MID AND UPPER-LEVEL JET STREAKS
ROUNDING THE BASE OF THE PARENT TROUGH...SUFFICIENT VERTICAL SHEAR
WILL EXIST FOR A FEW LONGER-LIVED STORMS WITH A RISK FOR LOCALLY
STRONG WIND GUSTS AND PERHAPS SOME HAIL.
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z
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