DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 021934
SWODY1
SPC AC 021932

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0232 PM CDT TUE JUL 02 2013

VALID 022000Z - 031200Z

...THERE IS A SLGT RISK OF SVR TSTMS SRN AZ INTO SRN HIGH PLAINS
THIS AFTERNOON AND EVENING...

EARLIER THOUGHTS REGARDING CONVECTION ACROSS THE CONUS REMAIN. NO
CHANGES TO 1630Z OUTLOOK.

..DARROW.. 07/02/2013

.PREV DISCUSSION... /ISSUED 1120 AM CDT TUE JUL 02 2013/

...SYNOPSIS...

A SLIGHT RETROGRESSION OF THE HIGH AMPLITUDE CONUS RIDGE-TROUGH
PATTERN IS FORECAST DURING THE D1 PERIOD...TO THE S OF A MORE
PROGRESSIVE POLAR AIR STREAM ACROSS CANADA. IN THE LOW LEVELS...THE
PRIMARY SYNOPTIC FRONT WILL REMAIN QUASI-STATIONARY FROM THE UPPER
OH VALLEY/LOWER GREAT LAKES TO CNTRL GULF COAST BEFORE ARCING
THROUGH THE NWRN G.O.M. AND THE HIGH PLAINS.

...SRN AZ INTO SRN HIGH PLAINS THIS AFTERNOON AND EVENING...

THE LARGE-SCALE PATTERN REMAINS QUITE SIMILAR TO PAST
DAYS...INCLUDING THE PRESENCE OF A WEAK UPSTREAM IMPULSE PROGRESSING
SWD THROUGH WRN CO. AND WHILE THE THERMODYNAMIC ENVIRONMENT WILL
NOT BECOME OVERLY UNSTABLE /I.E. MLCAPE OF 500-1500 J PER KG/...12Z
REGIONAL SOUNDINGS INDICATE THE PRESENCE OF MODESTLY STRONG MID AND
UPPER-LEVEL FLOW WHICH MAY PROMOTE STORM ORGANIZATION/SUSTENANCE.
FORCING FOR ASCENT ATTENDANT TO THE ABOVE-MENTIONED PERTURBATION
COUPLED WITH STRENGTHENING TERRAIN-INDUCED CIRCULATIONS WILL PROMOTE
AN INCREASE IN TSTMS THIS AFTERNOON WITH EVENTUAL UPSCALE GROWTH
INTO CLUSTERS BY THIS EVENING. DAMAGING WINDS WILL BE THE PRIMARY
HAZARD...THOUGH SOME HAIL IS POSSIBLE.

...ATLANTIC STATES THIS AFTERNOON AND EVENING...

A VERY MOIST AIR MASS WILL REMAIN COLOCATED WITH MODESTLY STRONG SLY
DEEP-LAYER FLOW TODAY...BETWEEN MS VALLEY TROUGH AND A RIDGE OVER
THE WRN ATLANTIC. WIDESPREAD CLOUDS WILL LIMIT MORE ROBUST
DESTABILIZATION...THOUGH WHERE POCKETS OF STRONGER HEATING CAN
OCCUR...MLCAPE VALUES MAY APPROACH 1500-2000 J/KG. SIMILAR TO PAST
DAYS...EXPECT A GRADUAL INCREASE IN STORM COVERAGE AND INTENSITY
THIS AFTERNOON WITH SOME POTENTIAL FOR MARGINAL SUPERCELL AND/OR
BOWING STRUCTURES CAPABLE OF LOCALLY DAMAGING WINDS AND A POSSIBLE
BRIEF TORNADO OR TWO. FOR ADDITIONAL NEAR-TERM GUIDANCE...SEE MCD
1316.

...OH VALLEY THIS AFTERNOON AND EVENING...

WEAK PERTURBATIONS PIVOTING AROUND PARENT UPPER LOW WILL FOSTER
SCATTERED TSTMS AMIDST AN ENVIRONMENT FEATURING MODEST AMOUNTS OF
INSTABILITY AND VERTICAL SHEAR. ISOLATED OCCURRENCES OF HAIL AND
DAMAGING WINDS WILL BE POSSIBLE THROUGH THIS EVENING BEFORE STORMS
WEAKEN WITH THE LOSS OF DAYTIME HEATING.

...INTERIOR PACIFIC NW/NRN INTERMOUNTAIN REGION THIS AFTERNOON AND
EVENING...

STRENGTHENING TERRAIN-INDUCED CIRCULATIONS WILL BE AUGMENTED BY A
WEAK IMPULSE OR TWO ROTATING AROUND THE WRN PERIPHERY OF THE UPPER
HIGH TO FOSTER ISOLATED TSTMS LATER TODAY. GIVEN THE COMBINATION OF
STEEP LAPSE RATES AND A RELATIVELY MOIST AIR MASS /I.E. PW VALUES OF
1.0-1.5 INCHES/...SUFFICIENT INSTABILITY WILL EXIST TO SUPPORT A FEW
INTENSE STORMS CAPABLE OF LOCALLY STRONG WIND GUSTS AND/OR HAIL.

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