[SWODY1] SWODY1

[SWODY1 at goshenarc.org]

ACUS01 KWNS 201247
SWODY1
SPC AC 201245

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0745 AM CDT WED APR 20 2005

VALID 201300Z - 211200Z

THERE IS A MDT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 40 N
GLD 10 WNW AKO 30 SE CYS 30 WSW BFF 10 NNE AIA 25 W MHN 10 NNW EAR
35 NNE HLC 40 N GLD.

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 50 NW
DRT 30 E BGS 50 SSW GAG 30 ESE GAG 30 N FSI 55 S BWD 60 WSW COT.

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 15 SE
BOS 25 WSW MSV 15 SSE PIT 20 WSW CMH 45 S HUF STL 15 ESE MKC 25 WSW
ICT 30 ESE GLD 50 NNE LAA 15 S DEN 50 WSW LAR 50 SSE CPR 60 WSW RAP
20 SE PHP 40 NNE BUB 25 SSE OMA 30 WSW DSM 45 WSW ALO 30 SE MMO 25
WNW FDY 25 WNW FDY 15 NE CLE 35 N BUF 20 SSW BTV 20 SSW PWM.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 20 SSW P07 25 WNW BGS
35 NNE AMA 45 ESE LBL 30 WNW GCK 25 ENE ALS 45 WSW MTJ 20 SSW U24 30
NNE ELY 40 SSE BAM 80 ESE 4LW BKE 3DU 35 SE GDV 40 N MBG 15 SW ABR
30 N OTG 25 W VOK 10 SSW MTW APN ...CONT... 30 SSW WAL 20 E LYH CSV
50 WNW CHA 40 NNW BHM 35 WSW 0A8 30 SE MOB.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 45 WNW 3B1 45 NW EPM.

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF NE CO  AND SW
NEB...

...THERE IS A SLGT RISK OF SVR TSTMS OVER  PARTS OF THE CNTRL
PLNS...MIDWEST AND OH VLY...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF NY/NRN PA AND NEW
ENG...

...SYNOPSIS...
NE NV UPR LOW EXPECTED TO DRIFT SLOWLY NE...AND THEN N OR NNW...
ACROSS NW UT AND SRN ID THIS PERIOD AS SYSTEM REMAINS PART OF REX
BLOCK SETUP OVER THE PACIFIC NW.  SPEED MAX NOW ROUNDING BASE OF THE
LOW OVER SRN NV/NW AZ SHOULD REDEVELOP NE INTO ERN CO BY 12Z
THURSDAY.  FARTHER S...WV DATA SUGGEST LINGERING PRESENCE OF AN
ILL-DEFINED SRN BRANCH JET EXTENDING FROM NRN BAJA ACROSS NRN
CHIHUAHUA INTO SW TX.  THIS BRANCH OF FLOW MAY TEND TO BECOME MORE
ANTICYCLONIC WITH TIME AS UPR LEVEL FLOW OVER THE SRN PLNS BACKS
SLIGHTLY AHEAD OF NV/AZ IMPULSE.

AT LWR LEVELS...LEE CYCLONE/THERMAL TROUGH SHOULD PERSIST OVER NE
CO/NW KS THROUGH THE PERIOD.  THE LOW...NOW IN WRN KS...MAY
RETROGRESS INTO ERN CO FOR AWHILE TODAY IN RESPONSE TO SURFACE
HEATING AND THE APPROACH OF NV/AZ SPEED MAX.  FRONT EXTENDING E FROM
THE LOW INTO THE LWR GRT LKS SHOULD REMAIN NEARLY STATIONARY ACROSS
SRN NEB...BUT WILL LIKELY ACCELERATE SEWD WITH INCREASING EWD EXTENT
AS A NRN STREAM DISTURBANCE AMPLIFIES ACROSS ONTARIO/QUEBEC.

...NE CO/WRN AND SW NEB...
SEVERE WEATHER SETUP OVER THE CNTRL HI PLNS EWD TO THE LWR MO VLY
EXPECTED TO CLOSELY RESEMBLE YESTERDAY'S...EXCEPT THAT THE MEAN FLOW
AND SHEAR SHOULD BE CONSIDERABLY STRONGER...ESPECIALLY OVER CO/WY
AND WRN PORTIONS OF NEB AND KS AS GRT BASIN SPEED MAX APPROACHES THE
CNTRL RCKYS.

COMBINATION OF SUSTAINED LOW LEVEL SLY FLOW OVER THE LWR PLNS... AND
MOISTURE RECYCLED THROUGH OVERNIGHT MCSS IN NEB...SUGGEST THAT AMPLE
INSTABILITY /SBCAPE OF 1000 TO 2000 J PER KG/ FOR SEVERE STORMS WILL
DEVELOP N AND NE OF ERN CO SURFACE LOW BY AFTERNOON AS HEATING
OCCURS BENEATH ALREADY STEEP MID LEVEL LAPSE RATES.  COUPLED WITH
35-40 KT SSWLY DEEP SHEAR..SETUP WILL BE FAVORABLE FOR A FEW
SUSTAINED SUPERCELLS WITH VERY LARGE HAIL/HIGH WIND IN MODERATE RISK
AREA.  TORNADO POTENTIAL SHOULD BE MAXIMIZED AS STORMS CROSS AXIS OF
ENHANCED LOW LEVEL VEERING N OF LOW AND/OR JUST N OF OUTFLOW
BOUNDARY LEFT FROM OVERNIGHT CONVECTION.

TEMPORAL BACKING OF MID AND UPR LEVEL FLOW WITH TIME OVER THE CNTRL
HI PLNS...AND THE LINEAR FORCING THAT WILL EXIST WITH THE ASSOCIATED
MERIDIONALLY-ORIENTED MID LEVEL THERMAL GRADIENT...DO CALL INTO
QUESTION THE PREDOMINANT CONVECTIVE MODE THAT WILL EXIST IN THE
MODERATE RISK AREA.  IN SHORT...WHILE SHEAR AND INSTABILITY WILL BE
FAVORABLE FOR STRONG...DISCRETE SUPERCELLS...IT IS NOT CLEAR ATTM
THAT WILL INDEED BE THE PREDOMINANT CONVECTIVE MODE. 
NEVERTHELESS...EVEN IF STORMS DO QUICKLY MERGE INTO SOME SORT OF AN
MCS...GIVEN STRENGTH OF SHEAR AND INSTABILITY IN THE NEARBY
ENVIRONMENT...POTENTIAL WILL STILL EXIST FOR SIGNIFICANT HAIL/HIGH
WIND AND POSSIBLE TORNADOES...ESPECIALLY DURING THE EARLY STAGES OF
STORM/MCS DEVELOPMENT.

AS LLJ STRENGTHENS...BOTH DIURNALLY AND IN RESPONSE TO CONTINUED
E/NE MOTION OF CO IMPULSE...EXPECT THAT MCS IN WRN/SW NEB WILL BEGIN
TO DEVELOP ESE ACROSS THE REMAINDER OF NEB AND/OR WILL BE JOINED BY
NEW STORMS FORMING INVOF FRONT OVER S CNTRL NEB SEWD INTO CNTRL/ERN
KS.  THIS ACTIVITY MAY YIELD HAIL AND POSSIBLY HIGH WIND.

...MID MS VLY/MIDWEST...
A WEAK MCV MAY HAVE DEVELOPED FROM OVERNIGHT MCS IN NEB...AND MAY IN
PART BE ENHANCING THUNDERSTORMS NOW OVER IA.  THE LLJ IN THE REGION
DOWNSTREAM FROM THIS ACTIVITY WILL LIKELY REMAIN WEAK THROUGH THE
DAY.  BUT FAIRLY STEEP MID LEVEL LAPSE RATES ARE IN PLACE ACROSS NRN
IL AND IND..AND POTENTIAL WILL EXIST FOR AT LEAST MODERATE SURFACE
HEATING.  COUPLED WITH UNIDIRECTIONAL WLY FLOW AND LARGE
TEMP/DEWPOINT SPREADS...THIS MAY SUPPORT A BAND OR TWO OF
FORWARD-PROPAGATING AFTERNOON STORMS WITH THE POTENTIAL FOR HIGH
WIND.

...NRN PA/SRN NY INTO SRN NEW ENG...
DEEP WLY SHEAR WILL INCREASE TODAY FROM THE LWR GRT LKS E INTO SRN
NEW ENG AS SHORTWAVE TROUGH WHICH CROSSED THE UPR MS VLY YESTERDAY
BECOMES ABSORBED WITHIN AMPLIFYING NRN STREAM TROUGH.  MID LEVEL
LAPSE RATES ARE NOT AS STEEP OVER THIS REGION AS THEY ARE FARTHER W
ACROSS THE MIDWEST.  BUT STORMS ASSOCIATED WITH THE SHORTWAVE...
NOW OVER WRN LK ERIE...HAVE SURVIVED THE NIGHT AND SHOULD STRENGTHEN
AS THEY MOVE INTO HEATED DOWNSTREAM ENVIRONMENT ACROSS PA/NY.  OTHER
STORMS MAY FORM ALONG COLD FRONT DROPPING SE INTO NEW ENG.  GIVEN
THIS SETUP...SOME OF THE ACTIVITY MAY YIELD DAMAGING WIND AS
TEMP/DEWPOINT SPREADS WILL BE FAIRLY LARGE AND WIND FIELD WILL
INCREASE.

...TX/OK DRY LINE...
A CONDITIONAL THREAT FOR SUPERCELLS WILL ONCE AGAIN EXIST ALONG DRY
LINE/LEE TROUGH OVER THE SRN PLNS.  THERE MAY BE SOME TENDENCY FOR
LARGE SCALE RIDGING DOWNSTREAM FROM NV/AZ IMPULSE OVER THIS REGION
TODAY. BUT...AS ALREADY MENTIONED...SATELLITE LOOPS DO SUGGEST
PRESENCE OF A SRN BRANCH IMPULSE NOW OVER NRN CHIHUAHUA THAT WILL BE
FAVORABLY TIMED TO ENHANCE POTENTIAL FOR STORM INITIATION LATE THIS
AFTERNOON.  THE AIR MASS E OF THE DRY LINE HAS MOISTENED SOME
RELATIVE TO RECENT DAYS...AND SKIES ARE FREE OF LOW CLOUDS ATTM
ACROSS NW TX/WRN OK.  AMPLE INSTABILITY WILL EXIST FOR LARGE HAIL
AND PERHAPS A TORNADO IF STORMS DO INDEED FORM.

..CORFIDI/TAYLOR.. 04/20/2005

...NOTICE...
THE STATION RELATIVE POINTS IN THIS PRODUCT ARE NOW AVAILABLE
SEPARATELY UNDER THE WMO HEADINGS WUUS01 PTSDY1...
WUUS02 PTSDY2...WUUS03 PTSDY3.  THE INCLUSION OF POINTS
IN THIS DISCUSSION WILL BE DISCONTINUED AFTER THE 2005
CONVECTIVE SEASON.  A PUBLIC NOTIFICATION STATEMENT (PNS)
WILL PROVIDE DETAILS ON THE TRANSITION.