[SWODY1] SWODY1

[SWODY1 at goshenarc.org]

ACUS01 KWNS 160552
SWODY1
SPC AC 160548

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1248 AM CDT SUN MAY 16 2004

VALID 161200Z - 171200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM PHP
AXN IWD VOK 50 NE ALO HSI 45 SSW EAR DDC 55 E AMA PVW CVS TCC 40 NW
IML 30 E AIA CDR 20 S RAP PHP.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 65 E MQT 35 SSW ESC
MSN END 70 NW ABI 40 WNW SJT 20 NW DRT ...CONT... 40 SSE DMN 65 NW
TCS 30 SSE ALS COS 4FC 35 NE GJT 30 SSW SLC 70 E BNO 40 SW PDT 30 NE
PDX 20 NW BLI ...CONT... 50 NW HVR 45 WSW HVR 75 NE BIL BIS FAR 30
NNW HIB 35 NNW ELO.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 ESE ECG FAY 35 WSW
FLO 10 SSE CHS ...CONT... 60 N BRO 25 N NIR LFK HOT 40 NW EVV UNI
LBE 25 SSW EEN BOS.

...THERE IS A SLGT RISK OF SVR TSTMS NEB/SD BORDER REGION ENEWD TO
UPPER MS VALLEY...AND SWD THROUGH S-CENTRAL HIGH PLAINS...

...SYNOPSIS...
MID/UPPER LEVEL HEIGHT PATTERN IS FCST TO FLATTEN SOMEWHAT ACROSS
CONUS THROUGH PERIOD...WITH BROAD ZONE OF WLY TO WSWLY FLOW ACROSS
NRN CONUS.  PRINCIPAL FEATURE OF INTEREST ALOFT WILL BE SHORTWAVE
TROUGH NOW EVIDENT ON MOISTURE CHANNEL IMAGERY OVER ERN ORE.  THIS
PERTURBATION IS FCST TO MOVE EWD...REACHING INVOF SERN MT/NWRN
SD/NERN WY BY 17/00Z...AND WRN MN/ERN SD WITHIN 12 HOURS THEREAFTER.
 SOMEWHAT FASTER SPECTRAL PROG WOULD RESULT IN MORE MIDLEVEL FORCING
OVER OUTLOOK AREA SOONER...CONTRIBUTING TO EARLIER SEVERE POTENTIAL
THIS AFTERNOON.  HOWEVER...CONFIDENCE IS HIGHER IN 00Z ETA/NGM PROGS
OF THIS SYSTEM...WHICH ARE STRONGLY SUPPORTED BY MEAN FIELDS FROM
21Z SREF GUIDANCE.  

IN RESPONSE TO APCHG TROUGH ALOFT...SFC CYCLOGENESIS ALREADY
UNDERWAY OVER CENTAL HIGH PLAINS SHOULD INTENSIFY AND FOCUS MORE
TIGHTLY OVER CO/NEB BORDER REGION BY THIS AFTERNOON.  MEANWHILE COLD
FRONT NOW MOVING SEWD ACROSS DAKOTAS WILL DECELERATE
OVERNIGHT...THEN BECOME WARM FRONT DURING DAY...EXTENDING FROM NRN
WI SWWD ACROSS CENTRAL MN...SERN SD AND CENTRAL/WRN BORDER SEGMENT
OF SD/NEB.  EFFECTIVE FRONTAL POSITION MAY BE OFFSET SOMEWHAT
FARTHER S BY MORNING CONVECTION OVER NEB/SD BORDER AREA...AND THERE
IS SOME POTENTIAL FOR ADDITIONAL CONVECTION TO ITS N THROUGH MUCH OF
THE DAY WHICH WOULD TIGHTEN BAROCLINIC GRADIENT AND PREVENT MUCH NWD
MOVEMENT.  LEE TROUGH SHOULD EXTEND NEWD FROM LOW TO FRONT...AND
SSWWD ACROSS SERN CO AND EXTREME ERN NM...BY MID-AFTERNOON. 
OVERNIGHT...FRONTAL-WAVE LOW SHOULD FORM OVER NERN NEB/SERN SD
REGION AND MOVE INTO CENTRAL MN...WHILE FRONT SURGES SEWD AGAIN AS
COLD FRONT...OVER MUCH OF WRN/CENTRAL NEB AND NERN CO.

...NEB/SD TO MN/WI...
BEST OVERLAP OF SEVERE TSTM INGREDIENTS...PARTICULARLY
INSTABILITY/SHEAR/LIFT...ARE FCST INVOF WARM FRONT OVER NEB/SD
BORDER REGION...FROM MID AFTERNOON INTO EARLY EVENING. SUPERCELLS
WITH SEVERE HAIL/WIND AND A FEW TORNADOES ARE POSSIBLE.  STRENGTH OF
SHEAR AND STEEP LAPSE RATES INDICATE A FEW TSTMS MAY PRODUCE VERY
LARGE/DAMAGING HAIL.  THIS CONVECTION AND/OR ADDITIONAL DEVELOPMENT
AFTER DARK NEAR WARM FRONT SHOULD EVOLVE INTO MCS OVER SERN SD/NWRN
IA/SWRN MN/NERN NEB REGION...MOVING ENEWD TOWARD WI WITH HAIL AND
DAMAGING WIND RISK.

STRONGEST CONVERGENCE AND MOST PROBABLE AREA FOR INITIATION OF
SEVERE TSTMS WILL BE INVOF FRONT...AND PERHAPS ALONG SEGMENT OF
TROUGH EXTENDING FROM FRONT SWWD TO LEE CYCLONE.  PRIMARY CAVEAT
ATTM INVOLVES QUALITY OF BOUNDARY LAYER MOISTURE...WITH SFC DEW
POINTS GENERALLY ONLY 50S F IN WARM SECTOR ADJACENT TO FRONT. 
STILL...THERE MAY BE NARROW CORRIDOR IN BAROCLINIC ZONE WHERE LCL
REMAINS RELATIVELY LOW...IN ENVIRONMENT OF TYPICALLY ENHANCED S-R
INFLOW AND BOUNDARY LAYER VORTICITY...ENHANCING TORNADO POTENTIAL
FOR STORMS INTERACTING WITH AND/OR MOVING ALONG FRONT. EXPECT
ROUGHLY 9 DEG C/KM MIDLEVEL LAPSE RATES HELPING TO COUNTERACT LACK
OF RICHER LOW LEVEL MOISTURE ENOUGH FOR 1500-2500 J/KG MLCAPE JUST S
OF FRONT.  VERTICAL SHEAR PROFILES FAVOR SUPERCELL MODES WITH
POTENTIAL FOR BOW EVOLUTION IN EVENTUAL CONVECTIVE COMPLEX.  LATE
AFTERNOON/EARLY EVENING FCST HODOGRAPHS SUGGEST 300-500 J/KG SRH IN
0-3 KM LAYER WITHIN THAT PORTION OF FRONTAL ZONE SUPPORTING
SFC-BASED LIFTED PARCELS...AND 200-300 J/KG SRH FARTHER S OVER WARM
SECTOR.  0-6 KM SHEARS OF 40-50 KT SHOULD BE COMMON.

THIS IS A SITUATION WHERE ONLY ONE STEP INCREASE IN EITHER SEVERE
HAIL OR TORNADO PROBABILITIES WOULD COMPEL MDT CATEGORICAL RISK
INVOF NEB/SD BORDER...WHICH WOULD BE LIKELY WITH HIGHER DEW POINTS
AND BETTER SPATIAL CERTAINTY REGARDING FRONTAL POSITION.  SUCH AN
UPGRADE MAY BE NEEDED IN A SUBSEQUENT OUTLOOK IF THESE FACTORS
BECOME MORE FAVORABLE.

...SRN/CENTRAL HIGH PLAINS...
ISOLATED TO WIDELY SCATTERED TSTMS MAY DEVELOP DURING 21Z-00Z TIME
FRAME INVOF LEE TROUGH/DRYLINE...AND EWD 50-100 NM ACROSS HIGH
PLAINS FROM ERN NM/TX PANHANDLE NNEWD ACROSS WRN KS AND SWRN NEB. 
CAPPING WILL LIMIT COVERAGE...BUT ANY SUSTAINED STORMS COULD BECOME
SUPERCELLS...RELATIVELY HIGH-BASED WITH POTENTIAL FOR LARGE HAIL. 
THOUGH DEEP-LAYER KINEMATIC PROFILES WEAKEN WITH SWD EXTENT...THEY
FAVOR STRONGLY DEVIANT AND SLOW STORM MOTIONS AS FAR S AS MUCH OF TX
PANHANDLE.  THEREFORE...FCST STORM-RELATIVE HODOGRAPHS REMAIN
FAVORABLE FOR SUPERCELLS...WITH 0-3 KM SRH POSSIBLY IN 200-300 J/KG
RANGE FOR CELLS MOVING VARIOUS DIRECTIONS BUT LESS THAN 10 KT. 
ACTIVITY FROM WRN KS SSWWD -- WELL S OF WARM FRONT -- WILL BE
STRONGLY TIED TO DIURNAL/DIABATIC HEATING PROCESSES AND SHOULD
DIMINISH AFTER DARK.

..EDWARDS.. 05/16/2004

...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.