MESOSCALE DISCUSSION 0584 NWS STORM PREDICTION CENTER NORMAN OK 0234 AM CDT TUE APR 08 2008 AREAS AFFECTED...NERN OK...SWRN MO...NWRN AR CONCERNING...SEVERE THUNDERSTORM WATCH 170... VALID 080734Z - 080830Z THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 170 CONTINUES. ...WW WILL BE REISSUED TO INCLUDE MUCH OF NERN OK INTO SWRN MO AND NWRN AR... UNSTABLE AIRMASS HAS YET TO BE DISPLACED OVER NERN OK...PER CONTINUED SUPERCELL ACTIVITY AND MORE RECENTLY INCREASING DEEP CONVECTION ALONG ADVANCING COLD FRONT ALONG I-35 NORTH OF OKC. LATEST THINKING IS STEEP MID LEVEL LAPSE RATES AND MODERATE MUCAPE JUST NORTH OF WARM FRONT WILL PROVE MORE THAN ADEQUATE FOR SEVERE THUNDERSTORMS INTO THE EARLY DAYLIGHT HOURS. COLD FRONTAL PASSAGE SHOULD END ANY SEVERE THREAT AS NWLY FLOW DEEPENS AND SHUNTS BUOYANT AIRMASS INTO THE MID MS VALLEY. ..DARROW.. 04/08/2008 MESOSCALE DISCUSSION 0583 NWS STORM PREDICTION CENTER NORMAN OK 1105 PM CDT MON APR 07 2008 AREAS AFFECTED...N CNTRL INTO NERN OK CONCERNING...SEVERE THUNDERSTORM WATCH 170... VALID 080405Z - 080530Z THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 170 CONTINUES. DAMAGING WIND POTENTIAL MAY INCREASE NEXT FEW HOURS. VIGOROUS NEW CONVECTIVE DEVELOPMENT NEAR/NORTH THROUGH NORTHEAST OF OKLAHOMA CITY CONTINUES TO INTENSIFY WITHIN ZONE OF STRONG LOW-LEVEL CONVERGENCE...JUST NORTH OF A QUASI-STATIONARY SURFACE FRONT EXTENDING EAST NORTHEASTWARD ALONG THE INTERSTATE 44 CORRIDOR INTO NORTHEAST OKLAHOMA. ALTHOUGH FLOW FIELDS ARE GENERALLY MODERATE IN STRENGTH...PRONOUNCED VEERING WITH HEIGHT IS CONTRIBUTING TO STRONG DEEP LAYER SHEAR WITHIN MODERATELY UNSTABLE ENVIRONMENT. GIVEN PROXIMITY TO THE SURFACE FRONT...AN ISOLATED TORNADO IS NOT OUT OF THE QUESTION IN THE NEAR TERM. HOWEVER... EVEN SOUTH OF THE FRONT..LOW-LEVEL THERMODYNAMIC STRUCTURE IN FORECAST SOUNDINGS SUGGEST THAT THIS PROBABILITY IS LOW. IT APPEARS MORE PROBABLE THAT THE ISOLATED SUPERCELL COULD GROW UPSCALE INTO A SMALL MESOSCALE CONVECTIVE SYSTEM...ACCOMPANIED BY AN INCREASING THREAT FOR DAMAGING WIND GUSTS AS IT APPROACHES TULSA BETWEEN NOW AND 06Z. ..KERR.. 04/08/2008 MESOSCALE DISCUSSION 0582 NWS STORM PREDICTION CENTER NORMAN OK 0912 PM CDT MON APR 07 2008 AREAS AFFECTED...PARTS OF NW TX INTO CNTRL OK CONCERNING...TORNADO WATCH 169... VALID 080212Z - 080315Z THE SEVERE WEATHER THREAT FOR TORNADO WATCH 169 CONTINUES. NORTHERN PORTIONS OF WW MAY BE REPLACED WITH A NEW SEVERE THUNDERSTORM WATCH BY 03Z...OR ADDED TO WW 170. TRENDS WILL BE MONITORED FOR THE POSSIBILITY OF AN INCREASING SEVERE THREAT NORTH OF WW 170...BUT THE NEED FOR A WW IS NOT ANTICIPATED AT THE PRESENT TIME. SURFACE WARM FRONTAL ZONE NEAR THE INTERSTATE 40 CORRIDOR WEST OF OKLAHOMA CITY APPEARS THE MOST PROBABLE FOCUS FOR ANY VIGOROUS NEW CONVECTIVE DEVELOPMENT BETWEEN NOW AND 03-05Z. RUC GUIDANCE SUGGESTS MOST UNSTABLE CAPE OF 1000-2000 J/KG ACROSS THIS REGION... WHERE FORCING ON THE NOSE OF A 40 KT LOW-LEVEL JET WILL CONTRIBUTE TO LARGE SCALE ASCENT...AS A BROAD/LOW AMPLITUDE UPPER TROUGH PROGRESSES EAST OF THE CENTRAL ROCKIES THIS EVENING. THERE IS INCREASING CONCERN THAT WARMING AROUND 700 MB COULD SUPPRESS DEVELOPMENT EVEN ACROSS THIS REGION. AND...IF THIS OCCURS...MORE PROMINENT NEW CONVECTION MAY END UP FORMING FARTHER IN CLOSER PROXIMITY TO/OR NORTH OF THE KANSAS BORDER...WHERE INSTABILITY PROBABLY WILL ONLY BE SUPPORTIVE OF A MORE MARGINAL SEVERE HAIL THREAT. OTHERWISE...SOUTH OF WARM FRONT...LOSS OF HEATING ALONG THE DRY LINE IS EXPECTED TO PRECLUDE THE DEVELOPMENT OF NEW STORMS. AND ...ACTIVITY DEVELOPING EAST OF THE BOUNDARY SHOULD CONTINUE TO DIMINISH. ..KERR.. 04/08/2008 MESOSCALE DISCUSSION 0581 NWS STORM PREDICTION CENTER NORMAN OK 0652 PM CDT MON APR 07 2008 AREAS AFFECTED...PARTS OF NW TX INTO CNTRL OK CONCERNING...TORNADO WATCH 169... VALID 072352Z - 080145Z THE SEVERE WEATHER THREAT FOR TORNADO WATCH 169 CONTINUES. TRENDS ARE BEING MONITORED FOR THE POSSIBILITY OF AN ADDITIONAL WW TO THE NORTH/NORTHEAST OF WW. WITH SIGNIFICANT GULF MOISTURE RETURN YET TO BECOME FULLY ESTABLISHED...COUPLED WITH THE LOWER/MID TROPOSPHERIC WARMING THROUGH MUCH OF THE CENTRAL/SOUTHERN PLAINS...CONVECTIVE DEVELOPMENT HAS BEEN SLOWED ALONG DRY LINE AND SURFACE WARM FRONT ACROSS REGION. HOWEVER...UPPER FLOW IS IN THE PROCESS OF BECOMING INCREASINGLY DIFLUENT AND DIVERGENT...AND THIS FORCING IS EXPECTED TO BECOME FOCUSED ACROSS CENTRAL OKLAHOMA BETWEEN NOW AND 02-03Z. THIS IS EXPECTED TO BECOME COINCIDENT WITH STRONG LOW-LEVEL CONVERGENCE AND WARM ADVECTION ON THE NOSE OF A 40 KT SOUTHERLY LOW-LEVEL JET. AND...IN THE PRESENCE OF STRONG DEEP LAYER SHEAR/ MOST UNSTABLE CAPE OF 1000-2000 J/KG...STORM DEVELOPMENT NOW OCCURRING NORTH OF OKLAHOMA CITY...AND ACROSS NORTHWEST TEXAS INTO SOUTHWEST OKLAHOMA...MAY GROW INTO AN EXPANDING CONVECTIVE CLUSTER LATER THIS EVENING. UNTIL THEN...THE RISK FOR A FEW SUPERCELLS CONTINUES...ACCOMPANIED BY POTENTIAL FOR VERY LARGE HAIL/LOCALIZED DAMAGING WINDS AND POSSIBLY ISOLATED TORNADOES. ..KERR.. 04/07/2008 MESOSCALE DISCUSSION 0580 NWS STORM PREDICTION CENTER NORMAN OK 0452 PM CDT MON APR 07 2008 AREAS AFFECTED...PARTS OF NW TX...SW/CNTRL OK CONCERNING...TORNADO WATCH 169... VALID 072152Z - 072315Z THE SEVERE WEATHER THREAT FOR TORNADO WATCH 169 CONTINUES. RISK FOR VERY LARGE HAIL/LOCALIZED DAMAGING WIND GUSTS AND ISOLATED TORNADOES ARE EXPECTED TO INCREASE ACROSS PARTS OF SOUTHWEST OKLAHOMA BETWEEN NOW AND 07/00Z. INITIATION OF DEEP CONVECTIVE DEVELOPMENT IS NOW UNDERWAY ALONG DRY LINE NEAR/WEST THROUGH NORTH OF WICHITA FALLS. LINGERING INHIBITION/TENDENCY FOR WARMING ALOFT MAY BE INITIALLY SLOWING INTENSIFICATION. BUT...AN INCREASINGLY MOIST LOW-LEVEL INFLOW APPEARS LIKELY TO INCREASE CAPE TO 2000 J/KG IN THE VICINITY OF ACTIVITY...LIKELY SUPPORTING RAPID STRENGTHENING OF UPDRAFTS IN THE PRESENCE OF STRONG DEEP LAYER SUPPORTIVE OF SUPERCELLS. THIS WILL BE ENHANCED BY INCREASINGLY DIFLUENT AND DIVERGENT UPPER FLOW...WHICH APPEARS TO BE IN THE PROCESS OF SPREADING OUT INTO THE SOUTH CENTRAL PLAINS. AND...STORMS ARE EXPECTED TO BEGIN TO SPREAD NORTHEASTWARD TOWARD CENTRAL OKLAHOMA BY 07/00Z...WITHIN FOCUSED ZONE OF STRONG LOW-LEVEL WARM ADVECTION. ..KERR.. 04/07/2008