DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 291957
SWODY1
SPC AC 291955

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0255 PM CDT SAT JUN 29 2013

VALID 292000Z - 301200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF CENTRAL AND
ERN CO...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF WRN NEW
ENGLAND...

...DISCUSSION...
THE ONGOING FORECAST CONTINUES TO REFLECT CURRENT THINKING...WITH
FEW CHANGES NECESSARY ATTM. STORMS CONTINUE TO DEVELOP OVER
PORTIONS OF THE WEST -- THOUGH ISOLATED IN MOST AREAS DUE TO
PERSISTENT LARGE-SCALE RIDGING. ISOLATED SEVERE POTENTIAL REMAINS
APPARENT HOWEVER FROM PORTIONS WA AND NERN OREGON EWD TO WRN MT AS A
SHORT-WAVE TROUGH CRESTS THE RIDGE...AND ACROSS THE CENTRAL/ERN CO
VICINITY WITHIN A WEAK UPSLOPE-FLOW REGIME. FOR ADDITIONAL
SHORT-TERM INFORMATION...PLEASE REFER TO RECENTLY ISSUED SWOMCD 1305
AND 1306 FOR PARTS OF CO AND THE SWRN MT/NRN AND ERN ID VICINITY
RESPECTIVELY.

FARTHER E...WIDESPREAD SHOWERS AND THUNDERSTORMS CONTINUE ACROSS THE
MIDWEST/OH VALLEY...AND NEWD INTO NRN AND WRN NEW ENGLAND. THOUGH
GENERALLY WEAK FLOW ACROSS MOST OF THE MIDWEST WILL CONTINUE TO
HINDER ANY APPRECIABLE ORGANIZED/SEVERE STORM ACTIVITY...STRONGER
WINDS ALOFT ACROSS NEW ENGLAND SUPPORT ISOLATED THREATS FOR DAMAGING
WINDS AND/OR HAIL WITH A FEW OF THE MORE ROBUST UPDRAFTS.

FINALLY...CONVECTION IS ALSO INCREASING FROM LA ENEWD ACROSS THE
SOUTHEAST AND INTO THE ERN NC/SERN VA VICINITY. WITH A
MOIST/MODERATELY UNSTABLE AFTERNOON AIRMASS BUT MODEST
SHEAR...ISOLATED/LOW-END SEVERE RISK WITH THE STRONGEST CELLS
REMAINS APPARENT.

..GOSS.. 06/29/2013

.PREV DISCUSSION... /ISSUED 1124 AM CDT SAT JUN 29 2013/

...SYNOPSIS...

MID AND UPPER-LEVEL JET STREAKS FROM THE NRN PLAINS INTO LOWER MO
VALLEY WILL DEVELOP EQUATORWARD IN TANDEM WITH A VORTICITY MAXIMUM
CURRENTLY OVER THE UPPER MIDWEST...RESULTING IN FURTHER
AMPLIFICATION TO THE LONG-WAVE TROUGH PRESENT OVER ERN NORTH
AMERICA. OVER THE WRN STATES...A SHORT-WAVE TROUGH MOVING ONTO THE
PACIFIC NW COAST WILL PROGRESS NEWD THROUGH THE NRN INTERMOUNTAIN
REGION...ALONG THE NRN PERIPHERY OF AN UPPER HIGH CENTERED OVER THE
SWRN DESERTS. IN THE LOW LEVELS...A COLD FRONT EXTENDING FROM LOW
PRESSURE OVER SRN QUEBEC SWD THROUGH THE HUDSON VALLEY AND THEN SWWD
THROUGH THE CNTRL APPALACHIANS INTO LOWER-MS VALLEY WILL SLOWLY
PROGRESS EWD/SEWD.

...NRN/CNTRL NEW ENGLAND THIS AFTERNOON AND EVENING...

12Z UPPER-AIR ANALYSIS AND MORNING WATER VAPOR IMAGERY INDICATE A
SHORT-WAVE TROUGH PROGRESSING NNEWD THROUGH THE HUDSON VALLEY ON THE
CYCLONIC SIDE OF A 50 KT WIND MAXIMUM AT 500 MB. FORCING ASSOCIATED
WITH THIS FEATURE IN CONJUNCTION WITH LOW-LEVEL CONVERGENCE ALONG
EWD-PROGRESSING COLD FRONT ARE EXPECTED TO FOSTER WIDELY SCATTERED
SURFACE-BASED TSTMS THIS AFTERNOON WITHIN A MOIST WARM SECTOR /I.E.
LOWEST-100-MB MEAN MIXING RATIOS OF 13-15 G PER KG/ WHERE AFTERNOON
MLCAPE VALUES WILL APPROACH 1000-1500 J/KG. MODEL-DERIVED
HODOGRAPHS INDICATE A VERTICALLY VEERING WIND PROFILE WITH 40-50 KT
OF EFFECTIVE BULK SHEAR WHICH WILL BE SUPPORTIVE OF ORGANIZED STORM
MODES...INCLUDING SUPERCELLS CAPABLE OF LARGE HAIL...DAMAGING
WINDS...AND PERHAPS A TORNADO.

...CNTRL/SRN HIGH PLAINS THIS AFTERNOON AND EVENING...

THOUGH MIDLEVEL FORCING MECHANISMS WILL REMAIN NEGLIGIBLE...
LOW-LEVEL UPSLOPE FLOW INTO THE CO FRONT RANGE SWD TO THE RATON MESA
WILL CONTRIBUTE TO THE DEVELOPMENT OF SCATTERED TSTMS LATER THIS
AFTERNOON INTO EVENING. HERE...THE COLOCATION OF MODEST BOUNDARY
LAYER AND STEEP LAPSE RATES WILL YIELD MLCAPE OF AROUND 1000 J/KG
WITHIN THE WRN ENVELOPE OF STRONGER MID AND UPPER-LEVEL FLOW
ASSOCIATED WITH THE JET STREAKS MENTIONED IN THE SYNOPSIS. AS
SUCH...THE POTENTIAL FOR ORGANIZED/ROTATING UPDRAFTS WILL EXIST WITH
THE THREAT FOR LARGE HAIL AND DAMAGING WINDS PERSISTING THROUGH THIS
EVENING.

...WA CASCADES INTO NRN ROCKIES TODAY INTO THIS EVENING...

WIDELY SCATTERED ELEVATED TSTMS ARE ONGOING THIS MORNING ACROSS
PORTIONS OF CNTRL WA IN CONJUNCTION WITH A LEAD SHORT-WAVE TROUGH
PROGRESSING NEWD THROUGH THE REGION. 12Z REGIONAL SOUNDINGS AND
SATELLITE-DERIVED PW IMAGERY SHOW THE PRESENCE OF A RELATIVELY MOIST
AIR MASS /I.E. PW VALUES OF 1.0-1.25 INCHES/ WHICH COINCIDES WITH
MIDLEVEL LAPSE RATES OF AROUND 7 C/KM. EXPECT CURRENT STORMS TO
PERSIST THIS MORNING ACROSS CNTRL/ERN WA WITH ADDITIONAL
SURFACE-BASED STORM DEVELOPMENT ANTICIPATED BY AFTERNOON ALONG THE
CASCADE AND BITTERROOT RANGES AS TOPOGRAPHIC FORCING IS AUGMENTED BY
WEAK IMPULSES UPSTREAM OF THE CURRENT FEATURE MOVING THROUGH THE
COLUMBIA BASIN. ISOLATED OCCURRENCES OF LARGE HAIL AND/OR DAMAGING
WINDS WILL BE POSSIBLE GIVEN THE PRESENCE OF A MODERATELY UNSTABLE
AIR MASS AND AMPLE CLOUD-BEARING SHEAR.

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