AREAS AFFECTED...MUCH OF IA...SERN SD...NERN NEB...SWRN MN
CONCERNING...SEVERE THUNDERSTORM POTENTIAL VALID 291742Z - 291915Z
SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG OUTFLOW BOUNDARY AND WARM FRONT. A WW COULD BE REQUIRED NEXT HOUR OR SO. LATEST VISIBLE IMAGERY SHOWS MODERATE TO STRONG INSOLATION VICINITY OF OLD OUTFLOW BOUNDARY DRAPED NW-SE OVER CENTRAL IA WITH BOUNDARY LAYER CU INCREASING. DEWPOINTS CONTINUE TO INCREASE INTO THE MID TO UPPER 60S F THROUGH ADVECTION WHICH IS PROVIDING AN UNSTABLE AND HIGH RH BOUNDARY LAYER. CAP IS EXPECTED TO BREAK AS TEMPERATURES APPROACH 80 F AS INDICATED BY RUC FORECAST SOUNDINGS. AMPLE LOW LEVEL HELICITY ALONG OUTFLOW BOUNDARY COULD ALLOW FOR THE DEVELOPMENT OF TORNADOES.
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MESOSCALE DISCUSSION 0972 NWS STORM PREDICTION CENTER NORMAN OK 0102 PM CDT SAT MAY 29 2004
AREAS AFFECTED...PARTS OF N CNTRL/CNTRL KS...S CNTRL/SE NEB
CONCERNING...SEVERE THUNDERSTORM POTENTIAL VALID 291802Z - 292000Z
INITIATION OF INTENSE CONVECTION APPEARS POSSIBLE WITHIN NEXT 2 TO 3 HOURS. STORMS WILL RAPIDLY BECOME SEVERE...WITH TRANSITION TO LONG-LIVED SUPERCELLS WITH POTENTIAL FOR STRONG TORNADOES THEREAFTER.
WATER VAPOR IMAGERY INDICATES PERSISTENT BAND OF LOW/MID-LEVEL MOISTENING/LARGE-SCALE ASCENT NOW SHIFTING NORTHEASTWARD ACROSS THE TEXAS/OKLAHOMA PANHANDLE REGION. THIS APPEARS TO BE IN RESPONSE TO WARM ADVECTION IN WAKE OF SHORT WAVE TROUGH ALREADY LIFTING OUT OF THE CENTRAL PLAINS...AND AHEAD OF SHORT WAVE/JET STREAK DIGGING ACROSS THE GREAT BASIN. STRONGER FORCING WILL CONTINUE INTO THE CENTRAL PLAINS EARLY THIS AFTERNOON...AND BY THE 20-21Z TIME FRAME APPEARS LIKELY TO CURVE ALONG AN AXIS FROM THE VICINITY OF HILL CITY THROUGH AREAS NEAR/NORTH AND EAST OF SALINA.
OBJECTIVE ANALYSIS INDICATES BOUNDARY LAYER IS ALREADY BECOMING VERY UNSTABLE ACROSS CENTRAL/NORTHERN KANSAS...EAST OF SURFACE LOW NOW DEVELOPING TO THE WEST OF RUSSELL. LOWER/MID TROPOSPHERIC CAP IS CURRENTLY INHIBITING CONVECTIVE DEVELOPMENT...BUT AS LARGE-SCALE ASCENT INCREASES IN CAPPING LAYER NEXT FEW HOURS...STORMS LIKELY WILL DEVELOP.
CURRENT INDICATIONS ARE THAT INITIATION COULD OCCUR AS EARLY AS 21Z EAST OF HILL CITY...WITH SUBSEQUENT DEVELOPMENT EAST NORTHEASTWARD INTO THE CONCORDIA KS/HASTINGS AND BEATRICE NEB AREAS. GIVEN MAGNITUDE OF POTENTIAL INSTABILITY...STORMS WILL RAPIDLY BECOME SEVERE WITH VERY LARGE HAIL...BEFORE HODOGRAPHS BECOME INCREASINGLY FAVORABLE FOR TORNADIC SUPERCELLS IN THE 29/21-30/00Z TIME FRAME. BY THIS TIME...BOUNDARY LAYER DEW POINTS ARE EXPECTED TO CLIMB TO AROUND 70F...CONTRIBUTING TO FAVORABLE LOW-LEVEL THERMODYNAMIC ENVIRONMENT FOR STRONG...POSSIBLY LONG-TRACK...TORNADOES.
Today must be the "Day After Tomorrow". LOL
Areas affected...much of ia...sern sd...nern neb...swrn mn
Concerning...severe thunderstorm potential valid 291742z - 291915z
Scattered thunderstorms are expected to develop along outflow boundary and warm front. A ww could be required next hour or so. Latest visible imagery shows moderate to strong insolation vicinity of old outflow boundary draped nw-se over central ia with boundary layer cu increasing. Dewpoints continue to increase into the mid to upper 60s f through advection which is providing an unstable and high rh boundary layer. Cap is expected to break as temperatures approach 80 f as indicated by ruc forecast soundings. Ample low level helicity along outflow boundary could allow for the development of tornadoes.
--- Mesoscale discussion 0972 nws storm prediction center norman ok 0102 pm cdt sat may 29 2004
Areas affected...parts of n cntrl/cntrl ks...s cntrl/se neb Concerning...severe thunderstorm potential valid 291802z - 292000z
Initiation of intense convection appears possible within next 2 to 3 hours. Storms will rapidly become severe...with transition to long-lived supercells with potential for strong tornadoes thereafter.
Water vapor imagery indicates persistent band of low/mid-level moistening/large-scale ascent now shifting northeastward across the texas/oklahoma panhandle region. This appears to be in response to warm advection in wake of short wave trough already lifting out of the central plains...and ahead of short wave/jet streak digging across the great basin. Stronger forcing will continue into the central plains early this afternoon...and by the 20-21z time frame appears likely to curve along an axis from the vicinity of hill city through areas near/north and east of salina.
Objective analysis indicates boundary layer is already becoming very unstable across central/northern kansas...east of surface low now developing to the west of russell. Lower/mid tropospheric cap is currently inhibiting convective development...but as large-scale ascent increases in capping layer next few hours...storms likely will develop.
Current indications are that initiation could occur as early as 21z east of hill city...with subsequent development east northeastward into the concordia ks/hastings and beatrice neb areas. Given magnitude of potential instability...storms will rapidly become severe with very large hail...before hodographs become increasingly favorable for tornadic supercells in the 29/21-30/00z time frame. By this time...boundary layer dew points are expected to climb to around 70f...contributing to favorable low-level thermodynamic environment for strong...possibly long-track...tornadoes.