| Sep 1, 2012 0600 UTC Day 1 Convective Outlook | |
| Updated: Sat Sep 1 05:09:29 UTC 2012 | |
| Probabilistic to Categorical Outlook Conversion Table | |
| Categorical Graphic |
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| Probabilistic Tornado Graphic |
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| 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. |
| Probabilistic Damaging Wind Graphic |
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| 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. |
| Probabilistic Large Hail Graphic |
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| Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
SPC AC 010505 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1205 AM CDT SAT SEP 01 2012 VALID 011200Z - 021200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM NERN AR INTO SERN MO AND EXTREME SWRN IL... ...SYNOPSIS... REMNANT OF TD ISAAC LOCATED OVER WRN MO IS EMBEDDED WITHIN SYNOPTIC UPPER RIDGE. WITH WEAK STEERING FLOW ALOFT...THIS FEATURE WILL MOVE VERY SLOWLY EWD...REACHING SWRN IL BY 12Z SUNDAY. OTHERWISE...THE SYNOPTIC PATTERN WILL BE CHARACTERIZED BY A MEAN TROUGH IN THE WRN AND NERN U.S. WITH HIGH PRESSURE DOMINATING FROM THE CNTRL AND SRN PLAINS THROUGH THE SERN STATES. THE NRN STREAM SHORTWAVE TROUGH NOW OVER BRITISH COLUMBIA AND PACIFIC NW WILL CONTINUE EWD INTO ALBERTA AND NRN MT LATER SATURDAY ACCOMPANIED BY A COLD FRONT. VORTICITY MAXIMA EMBEDDED WITHIN WEAKER SRN STREAM TROUGH WILL SHEAR EWD AS THEY MOVE INTO A CONFLUENT FLOW REGIME OVER THE GREAT BASIN AREA. ...PORTIONS OF LOWER THROUGH MID MS VALLEY AND WRN TN VALLEY... REMNANTS OF ISAAC CONTINUE TO WEAKEN AND IS ENTRAINING DRYER AIR ALOFT INTO ITS SRN FLANK. THIS SUGGESTS THE BEST POTENTIAL FOR SFC HEATING AND GREATER INSTABILITY MAY DEVELOP FROM AR...SRN MO INTO WRN TN SATURDAY. A VORT MAX IS FORECAST TO ROTATE AROUND THE SRN PERIPHERY OF THE UPPER LOW...AND STORMS WILL LIKELY REDEVELOP WITHIN EVOLVING LOW LEVEL CONVERGENCE BAND FROM PARTS OF AR INTO SERN MO AS THE BOUNDARY LAYER DESTABILIZES. MODELS MAINTAIN A 40 KT SWLY LLJ ALONG SERN FLANK OF THE CIRCULATION WHERE 0-2 KM SHEAR /ALTHOUGH LESS THAN PREVIOUS DAYS/ MAY BE MARGINALLY SUFFICIENT FOR A THREAT FOR LOW LEVEL MESOCYCLONES AND A COUPLE OF TORNADOES. ISOLATED STRONG TO DAMAGING GUSTS MAY ALSO OCCUR WITH THE STRONGER STORMS...ESPECIALLY WHERE SBCAPE SHOULD BE MAXIMIZED FROM CNTRL THROUGH NERN AR INTO SERN MO. ...INTERMOUNTAIN REGION/EASTERN GREAT DIVIDE... CORRIDOR OF MODERATE SOUTHWESTERLY MID LEVEL FLOW /35-40 KT/ WILL EXTEND FROM SOUTHERN CA/DESERT SOUTHWEST TO THE NORTHERN ROCKIES ON SATURDAY. STORMS WILL LIKELY DEVELOP OVER THE HIGHER TERRAIN POSSIBLY AIDED BY EWD SHEARING VORT MAX. SOME OF THESE TSTMS MAY BE CAPABLE OF STRONG GUSTY WINDS AND/OR MARGINAL HAIL. ...AZ... TSTMS ARE EXPECTED TO BE A BIT MORE PREVALENT ON SATURDAY AS MOISTURE GRADUALLY INCREASES INTO PARTS OF AZ/LOWER CO RIVER VALLEY OVER THE NEXT 24-48 HR. THIS INCREASE IN MOISTURE COUPLED WITH A MODESTLY ENHANCED BELT OF SOUTH-SOUTHWESTERLY FLOW ALOFT MAY ALLOW FOR A FEW SUSTAINED/STRONGER TSTMS CAPABLE OF WIND AND/OR MARGINAL HAIL. ...CNTRL/EASTERN MT... HEIGHT FALLS ARE EXPECTED TO OCCUR OVER THE REGION ESPECIALLY INTO SATURDAY AFTERNOON/NIGHT IN ASSOCIATION WITH THE PROGRESSIVE SHORTWAVE TROUGH. ISOLATED TSTMS MAY DEVELOP OVER THE HIGHER TERRAIN AHEAD OF THE FRONT AND SHIFT NEWD THROUGH CNTRL AND ERN MT. IN SPITE OF STEEP LAPSE RATES/INCREASING VERTICAL SHEAR...THE PRIMARY LIMITATION WILL BE LIMITED MOISTURE/BUOYANCY...ALTHOUGH A DEEPLY MIXED BOUNDARY LAYER MAY CONTRIBUTE TO GUSTY WINDS WHERE TSTMS DEVELOP SATURDAY AFTERNOON/EARLY EVENING. ..DIAL/MOSIER.. 09/01/2012 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z