Tuesday, July 5, 2011

DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 052002
SWODY1
SPC AC 052000

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0300 PM CDT TUE JUL 05 2011

VALID 052000Z - 061200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE CNTRL AND NRN
PLAINS...

...THERE IS A SLGT RISK OF SVR TSTMS FOR A PART OF SRN AZ...

...SRN AZ...
ADDED A SMALL SLIGHT RISK DOWNSTREAM OF TSTMS DEVELOPING OVER THE
ERN MOGOLLON RIM/WHITE MTNS AND HIGHER TERRAIN OF SERN AZ. WITH
MODEST E/SELY STEERING FLOW /AROUND 20 TO 25 KT AT 500
MB/...ACTIVITY SHOULD DEVELOP TOWARDS THE PHOENIX TO TUCSON METRO
AREAS THROUGH EARLY EVENING. WITH MIDDLE 60S SURFACE DEW POINTS IN
PLACE AND MLCAPE AROUND 2000 J/KG...CONFIDENCE HAS INCREASED THAT AT
LEAST AN ISOLATED THREAT FOR SEVERE WINDS SHOULD EXIST WITH ANY
CLUSTERS PROPAGATING OFF THE HIGHER TERRAIN.

...CENTRAL PLAINS...
NO CHANGE TO CATEGORICAL SLIGHT RISK AREA BUT DID REMOVE 30 PERCENT
HAIL PROBABILITIES DUE TO SOME SPATIOTEMPORAL UNCERTAINTY OVER TSTM
COVERAGE IN THE LATE AFTERNOON GIVEN WEAK LOW-LEVEL CONVERGENCE.
NEVERTHELESS...WITH A STRONGLY UNSTABLE AIR MASS AND SUFFICIENT
EFFECTIVE SHEAR...ISOLATED SUPERCELLS APPEAR LIKELY WHERE STORMS
FORM. FOR ADDITIONAL SHORT-TERM DETAILS...PLEASE SEE MCD 1510.

...ERN CO/WY/MT AND AL/GA/CAROLINAS...
NO CHANGE TO PREVIOUS OUTLOOK.

..GRAMS/HART.. 07/05/2011

.PREV DISCUSSION... /ISSUED 1104 AM CDT TUE JUL 05 2011/

A LARGE UPPER RIDGE IS IN PLACE TODAY OVER MUCH OF THE
SOUTHERN/CENTRAL UNITED STATES...WITH THE PRIMARY WESTERLIES ALONG
THE US/CANADIAN BORDER. ANOTHER BAND OF SLIGHTLY STRONGER MID/UPPER
LEVEL FLOW WRAPS AROUND THE UPPER HIGH OVER THE CENTRAL
ROCKIES...PROVIDING 25-35 KNOT MID LEVEL WINDS TO PORTIONS OF NM/AZ
AS WELL AS WY/CO/NEB. BOTH OF THESE AREAS WILL HAVE SOME THREAT OF
SEVERE WEATHER LATER TODAY.

...CENTRAL PLAINS...
MORNING SATELLITE AND RADAR LOOPS SHOW AREAS OF REMNANT CONVECTION
OVER PARTS OF NORTHERN NEB AND WESTERN IA. A SURFACE BOUNDARY IS
SAGGING SOUTHWARD FROM THIS AREA AND EXTENDS ACROSS CENTRAL NEB.
PRESENT INDICATIONS ARE THAT THE STRONGEST DAYTIME HEATING AND
DESTABILIZATION WILL OCCUR SOUTH OF THE BOUNDARY AND AWAY FROM THE
CURRENT CONVECTION...MAINLY OVER SOUTHERN NEB AND NORTHERN KS. IT
APPEARS LIKELY THAT A CORRIDOR OF STRONG CAPE VALUES WILL DEVELOP BY
MID/LATE AFTERNOON IN THIS REGION...ALONG WITH A RATHER WEAK CAP.
SCATTERED AFTERNOON THUNDERSTORMS ARE LIKELY TO DEVELOP OVER
SOUTHERN NEB AND SPREAD EAST-SOUTHEASTWARD TOWARD NORTHWEST MO AFTER
DARK. SUFFICIENT EFFECTIVE SHEAR WILL PROMOTE ORGANIZED MULTICELL
OR SUPERCELL STRUCTURES CAPABLE OF LARGE HAIL AND DAMAGING WINDS.

...ERN CO/WY/MT...
MOST MODEL SOLUTIONS SHOW A LIKELIHOOD OF SCATTERED CONVECTION LATER
TODAY OFF THE HIGHER TERRAIN OF CENTRAL CO/WY AND SOUTHEAST MT.
THESE STORMS WILL SPREAD INTO THE ADJACENT PLAINS DURING THE LATE
AFTERNOON AND EVENING. STEEP LOW/MID LEVEL LAPSE RATES AND
SUFFICIENT DEEP LAYER SHEAR SUGGEST A RISK OF A FEW HIGH-BASED
SUPERCELLS CAPABLE OF DAMAGING WINDS AND HAIL.

...AZ...
THERE HAVE BEEN ONLY SUBTLE CHANGES TO THE OVERALL PATTERN ACROSS AZ
DURING THE PAST 2-3 DAYS. RATHER HIGH MOISTURE CONTENT ACROSS THE
AREA WILL ONCE AGAIN RESULT IN MODERATE TO STRONG INSTABILITY OVER
CENTRAL AND SOUTHERN AZ. WATER VAPOR LOOPS SHOWS A WEAK MID LEVEL
FEATURE MOVING FROM WESTERN NM INTO AZ. STEEP LOW LEVEL LAPSE RATES
AND AN EASTERLY COMPONENT TO THE STEERING FLOW WILL HELP ANY
CONVECTION THAT FORMS OVER EASTERN AZ TO SPREAD INTO THE LOWER
DESERTS. WHILE THOSE STORMS THAT FORM WILL POSE A LOCALIZED THREAT
OF DAMAGING WINDS...IT IS ONCE AGAIN UNCERTAIN IF STORMS WILL BE
ABLE TO GAIN SUFFICIENT MASS TO PRODUCE A LARGER COLD POOL...WHICH
WOULD POSE A MORE WIDESPREAD RISK OF DAMAGING WINDS. WILL MAINTAIN
ONLY LOW SEVERE PROBS AT THIS TIME DUE TO THESE UNCERTAINTIES.

...AL/GA/CAROLINAS...
ANOTHER DAY OF SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS IS
ANTICIPATED OVER THE SOUTHEAST STATES FROM AL INTO THE CAROLINAS.
NUMEROUS THUNDERSTORMS YESTERDAY HAVE LESSENED THE DEGREE OF
INSTABILITY AND MID LEVEL LAPSE RATES TODAY...WHICH SHOULD GENERALLY
DECREASE THE INTENSITY OF THE DOWNDRAFTS/WIND THREAT.
NEVERTHELESS...GUSTY TO DAMAGING WINDS WILL BE POSSIBLE IN THE
STRONGER CORES TODAY ACROSS THE REGION.

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