Sep-18-2004 0100 UTC Day 1 Convective Outlook
Updated: Sat Sep 18 01:01:50 UTC 2004
Categorical Graphic
20040918 0100 UTC Day 1 Outlook Graphic
Probablistic Tornado Graphic
20040918 0100 UTC Day 1 Tornado Probabilities Graphic
Probablistic Damaging Wind Graphic
20040918 0100 UTC Day 1 Damaging Wind Probabilities Graphic
Probablistic Large Hail Graphic
20040918 0100 UTC Day 1 Large Hail Probabilities Graphic
   SPC AC 180051
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0751 PM CDT FRI SEP 17 2004
   
   VALID 180100Z - 181200Z
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 15 SSW
   ILM 20 E RWI RIC 40 E CHO 45 NE CHO 10 SW MRB 25 N HGR CXY 20 SW ABE
   10 NNW PHL 30 ENE SBY.
   
   THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM LNK
   OMA 10 ESE LWD 45 S IRK 25 S SZL CNU 20 NE ICT 15 WSW SLN LNK.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 ENE CHS GSB 55 SW
   RIC 10 SE SHD 35 W SHD MGW IPT PSM.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 10 ESE PSX 30 SW AUS
   25 NNE ABI 25 NNW SPS 20 SSW ADM 30 ESE DAL LFK 10 E LFT 20 N BVE.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM GAG 10 ESE DDC 10 ENE
   HLC EAR MHE HON 10 NE ATY MSP 30 W LSE 15 ENE DBQ 35 W SPI 15 N SGF
   10 SE BVO END GAG.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 E CZZ 15 NW DAG 55
   NNW DRA 30 NW SGU GCN GUP ABQ 65 W CVS CNM 70 SE ELP.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 65 NW FCA 10 S S80 75
   E 4LW 10 SW EKA.
   
   GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 S SRQ 15 NNE MLB.
   
   ...THERE IS A SLGT RISK OF SVR TSTMS THIS EVENING ACROSS PARTS OF
   THE MID ATLANTIC COAST STATES....
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVERNIGHT ACROSS PARTS OF THE
   CENTRAL PLAINS/MID MISSOURI VALLEY....
   
   ...MID ATLANTIC COAST STATES...
   LOW-LEVEL HODOGRAPHS ARE STILL FAVORABLE FOR SUPERCELLS WITH
   TORNADOES IN AND AROUND THE WASHINGTON D.C. AREA.  HOWEVER...DIURNAL
   COOLING OF TROPICAL-TYPE BOUNDARY LAYER ACROSS EASTERN VIRGINIA AND
   THE DELMARVA PENINSULA IS EXPECTED TO RESULT IN DIMINISHING RISK FOR
   ADDITIONAL TORNADOES WITHIN NEXT COUPLE OF HOURS.  SLIGHTLY DRIER
   AIR IS ALREADY SPREADING EASTWARD THROUGH CENTRAL VIRGINIA/NORTH
   CAROLINA...EAST OF WEAKENING LOW/MID-LEVEL CIRCULATION CENTER
   ASSOCIATED WITH REMNANTS OF IVAN.  THIS WILL ADVECT ACROSS THE
   REMAINDER OF THE MID ATLANTIC COAST REGION BY LATE
   EVENING...CONTRIBUTING TO STABILIZING THERMODYNAMIC PROFILES.
   
   ...EAST TEXAS INTO THE CENTRAL GULF COAST...
   CONFLUENT LOW-LEVEL FLOW REGIME...IN WAKE OF TROUGH EMBEDDED WITHIN
   SUBTROPICAL WESTERLIES...IS PROVIDING FOCUS FOR ONGOING SCATTERED
   THUNDERSTORM ACTIVITY. INHIBITION IS WEAK DUE TO COOLER MID-LEVEL
   ENVIRONMENT RELATIVE TO THAT ACROSS THE SOUTHERN HIGH PLAINS/CENTRAL
   PLAINS.  AND WITH TEMPERATURES STILL NEAR/ABOVE 90F...IT MAY STILL
   BE ANOTHER FEW HOURS BEFORE BOUNDARY LAYER STABILIZES/CONVECTION
   DIMINISHES.
   
   ...CENTRAL PLAINS INTO MISSOURI VALLEY...
   MODELS SUGGEST LOWER/MID TROPOSPHERIC WARM ADVECTION/ISENTROPIC
   ASCENT WILL BECOME ENHANCED FROM PARTS OF NORTHEAST KANSAS INTO
   SOUTHEAST NEBRASKA/SOUTHWEST IOWA/NORTHWEST MISSOURI BY LATE
   EVENING.  THIS WILL OCCUR ON NOSE OF NOCTURNALLY STRENGTHENING
   LOW-LEVEL JET...WHICH APPEARS LIKELY TO PROVIDE SUFFICIENT
   FORCING/INFLUX OF MOISTURE TO OVERCOME CAP...SUPPORTING INCREASING
   CONVECTIVE DEVELOPMENT.  AIDED BY DIFLUENT AND AT LEAST WEAKLY
   DIVERGENT UPPER FLOW FIELD BETWEEN POLAR AND SUBTROPICAL JET
   AXES...A SUBSTANTIAL CLUSTER OF STORMS MAY EVENTUALLY EVOLVE...BASED
   ABOVE SURFACE/NEAR SURFACE INVERSION LAYER.  PRIMARILY DUE TO
   FAVORABLE THERMODYNAMIC ENVIRONMENT...MARGINALLY SEVERE HAIL APPEARS
   POSSIBLE IN STRONGEST STORMS.
   
   ...SOUTHERN PLATEAU...
   ONGOING CONVECTIVE ACTIVITY ACROSS EAST CENTRAL ARIZONA/CENTRAL AND
   SOUTHERN NEW MEXICO IS EXPECTED TO DIMINISH SHORTLY WITH LOSS OF
   DAYTIME HEATING.  HOWEVER...NORTHWARD MOISTURE TRANSPORT AND
   STRENGTHENING LOW-LEVEL WARM ADVECTION ARE PROGGED OVERNIGHT ACROSS
   THE LOWER COLORADO VALLEY...AHEAD OF TROUGH DIGGING INTO THE PACIFIC
   COAST. THIS MAY BECOME SUPPORTIVE OF SCATTERED THUNDERSTORM
   ACTIVITY BY 18/09-12Z.
   
   ...PACIFIC NORTHWEST...
   STRONGER MID-LEVEL COOLING NOW SPREADING INTO THE OLYMPICS/ CASCADES
   IS CONTRIBUTING TO SUFFICIENT INSTABILITY FOR SCATTERED/ BRIEF
   THUNDERSTORMS. THIS ACTIVITY MAY PERSIST THROUGH THE OVERNIGHT
   HOURS...GRADUALLY SHIFTING EAST OF THE MOUNTAINS INTO PARTS OF
   CENTRAL/EASTERN WASHINGTON AND OREGON.
   
   ...FLORIDA...
   WITH LOSS OF HEATING...SCATTERED ONGOING THUNDERSTORM ACTIVITY
   SHOULD GRADUALLY DIMINISH BY 18/06Z...AS BOUNDARY LAYER
   STABILIZES/LOW-LEVEL CONVERGENCE WEAKENS ACROSS THE SOUTHERN FLORIDA
   PENINSULA.
   
   ..KERR.. 09/18/2004
   
   ...NOTICE...
   FOR USERS DECODING THE POINTS PARAGRAPH HEREIN...LATITUDE AND
   LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK
   GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO
   HEADINGS WUUS01 PTSDY1...WUUS02 PTSDY2...AND WUUS03 PTSDY3.  THE
   INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED.
   
   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED FOR 0600Z