[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 240603
SWODY2
SPC AC 240603

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0103 AM CDT MON JUL 24 2006

VALID 251200Z - 261200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS NRN NEW ENGLAND...

...SYNOPSIS...
THE WRN STATES UPPER RIDGE WILL EXPAND TO THE N AND E ACROSS THE SRN
AND CNTRL PARTS OF THE COUNTRY ON TUE AS THE PRIMARY BELT OF WLYS
BECOMES SITUATED ALONG THE INTERNATIONAL BORDER.  A MID-LEVEL
SHORTWAVE TROUGH THAT WILL REACH SRN QUE BY EARLY TUE WILL EJECT
NEWD INTO ATLANTIC CANADA BY TUE EVE...SKIRTING PARTS OF NRN NEW
ENGLAND.  MEANWHILE...A SECONDARY DISTURBANCE WILL MOVE QUICKLY SEWD
THROUGH THE NRN PLAINS TO THE UPPER MS VLY DURING THE DAY TUE.

...NRN NEW ENGLAND...
THE SRN QUE H5 SHORTWAVE TROUGH WILL GLANCE ACROSS NRN NEW ENGLAND
DURING TUE AFTN WITH ASSOCIATED 40-50 KT JET...BOOSTING VERTICAL
SHEAR VALUES.  AIR MASS SHOULD GRADUALLY MOISTEN...BUT RECENT
INTRUSION OF A CP AIR MASS WILL LIKELY SLOW THE RETURN OF QUALITY
MOISTURE.  THIS...AND THE FACT THAT MID-TROPOSPHERIC LAPSE RATES
WILL GENERALLY BE BELOW 6 DEG C PER KM...SUGGEST THAT INSTABILITY
WILL BE MODEST AT BEST.  BUT...GIVEN MAGNITUDE OF ASCENT AND SHEAR
IN PLACE DURING PEAK HEATING...A FEW TSTMS WILL LIKELY PRODUCE
DAMAGING WIND GUSTS...PRIMARY OVER NRN MAINE.

...SWRN DESERTS...
EMILIA IS EXPECTED TO BECOME A HRCN AND MOVE JUST OFF THE WRN BAJA
COAST THROUGH TUE.  CLIMATOLOGICALLY...SIGNIFICANT GULF OF CA SURGES
OCCUR WHEN A TROPICAL SYSTEM TAKES A PATH SIMILAR TO EMILIA.  THIS
WILL LIKELY CAUSE AN DRAMATIC INCREASE IN BOUNDARY LAYER MOISTURE
ACROSS THE LWR DESERT REGIONS BY TUE AFTN/EVE AND COULD PLAY A ROLE
IN AN INCREASE IN TSTMS PROBABILITIES. MODELS SUGGEST THAT NELY
FLOW WILL INCREASE TO AOA 30 KTS AS THE BOUNDARY LAYER FLOW REMAINS
UPSLOPE DURING PEAK HEATING.  AS A RESULT...TSTMS COULD STRONGLY
PROPAGATE INTO THE LWR DESERTS DURING THE AFTN/EVE WITH DAMAGING
WINDS AND HAIL.  TYPICALLY... MESOSCALE PROCESSES...WHICH ARE
DIFFICULT TO PIN-POINT THIS FAR IN ADVANCE ACROSS THE SWRN
STATES...DICTATE STORM MODE AND EVOLUTION.  AS SUCH...A CATEGORICAL
SLGT RISK IS NOT WARRANTED ATTM.  BUT... THE REGION MAY NEED HIGHER
SEVERE PROBABILITIES IN FUTURE OTLKS.

...UPPER MS VLY/CORN BELT...
DIFFICULT FORECAST CONTINUES WITH RESPECT TO SEVERE TSTM
PROBABILITIES ACROSS THE REGION.  PRIMARY FORCING FOR ASCENT WILL BE
PULLING NEWD AWAY FROM THE REGION EARLY ON TUE AS THE STRONGER
SHORTWAVE TROUGH MOVES TO SERN CANADA. THE LOW-LEVEL
FLOW...HOWEVER...SHOULD REMAIN SWLY...MAXIMIZING WARM ADVECTION
REGIME DOWNSTREAM FROM STRONGER ELEVATED MIXED LAYER ACROSS THE MO
VLY.  AS A RESULT...CONVECTION/TSTMS WILL LIKELY DEVELOP THROUGHOUT
THE DAY FROM PARTS OF IA/SRN WI EWD TOWARD MI...OR WITHIN/NE OF THE
STRONGER LOW-LEVEL THERMAL AXIS.  VERTICAL SHEAR WILL REMAIN WEAK
AND SUGGESTS THAT THE SEVERE PROBABILITIES WILL REMAIN
LOW...ESPECIALLY IF SFC RIDGING BECOMES AS STRONG AS THE 00Z NAM
SUGGESTS.

FARTHER NW...A SEPARATE REGION OF SLIGHTLY HIGHER SEVERE
PROBABILITIES WILL EXIST ACROSS NRN/CNTRL MN TOWARD THE UPPER
GRTLKS.  THIS REGION WILL BE DOWNSTREAM FROM A WEAK IMPULSE.  00Z
MODEL SUITE DIFFER IN MAGNITUDE OF THIS WAVE. GIVEN THAT THE NAM IS
AN OUTLIER...HAVE GIVEN CREDENCE TO THE GFS/ECMWF IN A WEAKER WAVE. 
TSTMS WILL STILL REMAIN POSSIBLE...ALONG/AHEAD OF THE ASSOCIATED
COLD FRONT...BUT RELATIVELY WARMER MID-LEVEL TEMPERATURES MAY TEND
TO BE DETRIMENTAL TO WIDESPREAD TSTM INITIATION.  GIVEN A SUSTAINED
STORM...THE MAGNITUDE OF LAPSE RATES AND AT LEAST MODEST VERTICAL
SHEAR WILL BE FAVORABLE FOR ISOLD LARGE HAIL.

...CNTRL PLAINS...
HIGH-BASED TSTMS WILL LIKELY DEVELOP TUE AFTN/EVE ALONG/AHEAD OF A
LEE-TROUGH FROM ERN CO NEWD INTO NCNTRL NEB.  THIS REGION WILL
RESIDE ALONG THE SRN PERIPHERY OF THE UPPER MS VLY IMPULSE WITH
MODEST NWLY FLOW ALOFT.  GIVEN THE SLY LOW-LEVEL FLOW...SUFFICIENT
DIRECTIONAL SHEAR MAY EXIST FOR ISOLD ORGANIZED STORMS THAT PRODUCE
LARGE HAIL/DAMAGING WIND GUSTS.  ACTIVITY MAY DEVELOP INTO A LOOSELY
ORGANIZED MCS THAT WILL MOVE EWD INTO THE CORN BELT OVERNIGHT TUE.

...SERN TX...
TROPICAL AIR MASS WILL CONTINUE TO FLOW NWD ALONG ERN SIDES OF THE
UPPER LOW EXPECTED TO MIGRATE NWD INTO THE REGION ON TUE.  RESIDUAL
FRONT AND DEEPENING SFC LOW WILL MAINTAIN AN ESELY BOUNDARY LAYER
FLOW.  AS A RESULT...TSTMS THAT DEVELOP AND MOVE NWD MAY PRODUCE
ISOLD TORNADOES...ESPECIALLY AS THEY APPROACH THE OLD FRONT ACROSS
PORTIONS OF SERN TX.

..RACY.. 07/24/2006