Mesoscale discussion

0

Severe Storm Outlook Narrative for Srn Az Through Srn Nm And Far Wrn Tx concerning SEVERE POTENTIAL…WATCH UNLIKELY

Mesoscale discussion

0

Severe Storm Outlook Narrative for Parts Of Central And Srn Nm To Sern Az concerning SEVERE POTENTIAL…WATCH POSSIBLE

DY1 SWODY1 07:34Z

0

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.

DY1 SWODY1 04:22Z

0

VALID 021630Z – 031200Z

…THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN ROCKIES
AND SRN HIGH PLAINS…

…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.

..MEAD/GOSS.. 07/02/2013

Mesoscale discussion

0

Severe Storm Outlook Narrative for Parts Of Central And Ern Nc/Far Nern Sc/Parts Of South Central And Sern Va concerning SEVERE POTENTIAL…WATCH UNLIKELY

DY1 SWODY1 01:24Z

0

VALID 021320Z – 031200Z

…THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF NM AND A SMALL
PART OF AZ…

CORRECTED FOR WIND PROBABILITY LINE

…SYNOPSIS…
AMPLIFIED GRT BASIN RIDGE/MID MS VLY TROUGH PATTERN WILL PERSIST
THROUGH WED…WITH SLIGHT RETROGRESSION CONTINUING. A DISTURBANCE
NOW ENTERING WRN BC WILL FLATTEN THE NRN EXTENSION OF THE RIDGE
LATER TODAY/TNGT…BUT WILL HAVE MINIMAL EFFECT ON THE LWR 48.

FEATURES WILL REMAIN WEAK AT THE SFC. A DIFFUSE FRONT/TROUGH WILL
PERSIST FROM THE CNTRL GULF CST NWD INTO A LOW OVER WRN KY. FROM
THERE THE BOUNDARY WILL CONTINUE NE ACROSS THE UPR OH VLY AND NRN
APPALACHIANS. DIURNALLY-ENHANCED TSTMS…A FEW OF WHICH COULD BECOME
SVR…SHOULD FOCUS ALONG AND E OF THE FRONT THROUGH WED.
MEANWHILE…TERRAIN-INDUCED CIRCULATIONS MAY SUPPORT LOCALLY STRONG
TO SVR STORMS ON THE PERIPHERY OF THE WRN U.S. RIDGE.

…OH VLY TO APPALACHIANS/E CST TODAY…
SATELLITE SUGGESTS THAT A SLIGHT RETROGRESSION OF OH VLY TROUGH IS
IN PROGRESS ATTM…IN ASSOCIATION WITH A WWD WOBBLE OF W ATLANTIC
UPR RIDGE. THIS SHOULD ALLOW BAND OF SEASONABLY STRONG /30+ KT/ 700
MB SLY FLOW THAT YESTERDAY WAS CONFINED TO THE MID-ATLANTIC TO
EXPAND W TO INCLUDE THE OH VLY TODAY. AT THE SAME
TIME…HOWEVER…LITTLE CHANGE IS EXPECTED IN THE DEEP MOISTURE
FIELD…WITH PW VALUES AOA 2 INCHES REMAINING CONFINED TO AREAS E OF
THE APPALACHIANS FROM GA AND THE CAROLINAS NNE TO SRN NEW ENGLAND.

AS WAS THE CASE YESTERDAY…CLOUDS WILL LIMIT LOW-LVL
DESTABILIZATION OVER MUCH OF THE REGION…WITH THE GREATEST HEATING
EXPECTED E OF THE OH VLY UPR LOW…I.E. OVER PARTS OF TN…KY…AND
SRN IND/OH. DIURNAL STORMS IN THE LATTER REGION…FOCUSING ALONG AND
AHEAD OF ASSOCIATED SFC FRONT/TROUGH…COULD YIELD SVR HAIL AND
PERHAPS LOCALLY DMGG WIND GIVEN STRENGTH OF MID/UPR-LVL FLOW.

FARTHER E…SSW-NNE ORIENTED BANDS OF CONVECTION/EMBEDDED STORMS
APPEAR LIKELY WHERE POCKETS OF LOW-LVL HEATING OCCUR FROM GA AND THE
CAROLINAS NNE INTO NY/NEW ENGLAND. AN IDENTIFIABLE SHORTWAVE IMPULSE
IS NOT APPARENT ALONG THIS CORRIDOR THIS MORNING…IN CONTRAST TO
YESTERDAY. INDEED…WWD SHIFT OF ATLANTIC RIDGE SHOULD RESULT IN
RISING HEIGHTS ACROSS THE REGION. NEVERTHELESS…SLIGHTLY
CONFLUENT…VERY MOIST LOW-LVL FLOW IN THE PRESENCE OF
STRONGER-THAN-NORMAL MID/UPR LVL WINDS SUGGEST A CONDITIONAL RISK
FOR ISOLD DMGG WIND GUSTS AND/OR A BRIEF TORNADO OR TWO THROUGH
EARLY EVE.

…SRN RCKYS AND ADJACENT HIGH PLNS TODAY/TNGT…
SIMILAR TO YESTERDAY…MODERATE…DEEP NLY FLOW AT MID-LVLS AND
WEAK…DIURNALLY-DRIVEN UPSLOPE FLOW AT LWR LVLS SHOULD ONCE AGAIN
FOSTER AFTN STORM DEVELOPMENT OVER CO AND NM MOUNTAINS. MODEST
MOISTURE AVAILABILITY SHOULD SOMEWHAT LIMIT STORM
COVERAGE…ESPECIALLY IN CO…WHERE PW WILL REMAIN AOB .75 INCH.
SOMEWHAT GREATER MOISTURE WILL RESIDE IN NM…WHERE PW WILL REMAIN
AROUND 1 INCH WITH SFC DEWPOINTS IN THE UPR 50S/LWR 60S F. WITH 500
MB NLY WINDS AROUND 30 KTS…SUFFICIENT DEEP SHEAR WILL EXIST FOR
SUSTAINED/ORGANIZED STORMS. GIVEN STEEP LOW-LVL LAPSE RATES…THESE
MAY YIELD LOCALLY DMGG WIND AND ISOLD SVR HAIL AS THEY MERGE INTO A
SMALL CLUSTER OR TWO THROUGH EARLY TNGT.

…AZ THIS AFTN/EVE…
CURRENT CONVECTION/STORMS OVER SRN AZ WILL KEEP THE LWR DESERTS A
BIT MORE MOIST TODAY RELATIVE TO YESTERDAY. BUT CONDITIONS ALOFT AND
UPSTREAM /NNE/ACROSS UT AND THE FOUR CORNERS REGION WILL REMAIN
LARGELY UNCHANGED. SUFFICIENT MOISTURE /PW AROUND .75 INCH/ WILL BE
PRESENT FOR ANOTHER ROUND OF DIURNAL STORMS OVER THE HIGHER TERRAIN
OF AZ…BUT MOISTURE VALUES DO NOT APPEAR FAVORABLE FOR SUSTAINED
ACTIVITY/LARGE CLUSTERS SUCH AS THOSE THAT MIGHT ACCOMPANY A TRUE
MONSOON PATTERN. NEVERTHELESS…SATELLITE DOES SHOW WHAT APPEARS TO
BE AN UPR IMPULSE NOW ENTERING CNTRL UT THAT SHOULD BE
FAVORABLY-TIMED TO ENHANCE STORM DEVELOPMENT OVER THE AZ RIM COUNTRY
LATER TODAY. FORECAST WIND PROFILES SUGGEST THAT THIS ACTIVITY
SHOULD ONCE AGAIN MOVE/DEVELOP MAINLY SSWWD…WITH AN ASSOCIATED
RISK FOR ISOLD DMGG WIND GUSTS/LOCALIZED HABOOB CONDITIONS OVER THE
SE THIRD OF THE STATE.

…INTERIOR NORTHWEST/NRN INTERMOUNTAIN REGION THIS AFTN/EVE…
MID-LVL FLOW ON NW SIDE OF GRT BASIN RIDGE WILL VEER AND SLIGHTLY
STRENGTHEN LATER TODAY AS BC JET STREAM CONTINUES ENEWD. COUPLED
WITH STRONG SFC HEATING AND THE PRESENCE OF MODEST MOISTURE /PW AOA
.75 INCH/…SETUP MAY YIELD ISOLD TO WDLY SCTD AFTN TSTMS FROM NRN
CA AND WRN/NRN NV ENE INTO SRN/ERN ORE AND CNTRL/SRN ID. SOME OF THE
STORMS WILL BE CAPABLE OF STRONG DOWNDRAFTS AND POSSIBLY HAIL.

..CORFIDI/MOSIER.. 07/02/2013

DY1 SWODY1 12:57Z

0

VALID 021300Z – 031200Z

…THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF NM AND A SMALL
PART OF AZ…

…SYNOPSIS…
AMPLIFIED GRT BASIN RIDGE/MID MS VLY TROUGH PATTERN WILL PERSIST
THROUGH WED…WITH SLIGHT RETROGRESSION CONTINUING. A DISTURBANCE
NOW ENTERING WRN BC WILL FLATTEN THE NRN EXTENSION OF THE RIDGE
LATER TODAY/TNGT…BUT WILL HAVE MINIMAL EFFECT ON THE LWR 48.

FEATURES WILL REMAIN WEAK AT THE SFC. A DIFFUSE FRONT/TROUGH WILL
PERSIST FROM THE CNTRL GULF CST NWD INTO A LOW OVER WRN KY. FROM
THERE THE BOUNDARY WILL CONTINUE NE ACROSS THE UPR OH VLY AND NRN
APPALACHIANS. DIURNALLY-ENHANCED TSTMS…A FEW OF WHICH COULD BECOME
SVR…SHOULD FOCUS ALONG AND E OF THE FRONT THROUGH WED.
MEANWHILE…TERRAIN-INDUCED CIRCULATIONS MAY SUPPORT LOCALLY STRONG
TO SVR STORMS ON THE PERIPHERY OF THE WRN U.S. RIDGE.

…OH VLY TO APPALACHIANS/E CST TODAY…
SATELLITE SUGGESTS THAT A SLIGHT RETROGRESSION OF OH VLY TROUGH IS
IN PROGRESS ATTM…IN ASSOCIATION WITH A WWD WOBBLE OF W ATLANTIC
UPR RIDGE. THIS SHOULD ALLOW BAND OF SEASONABLY STRONG /30+ KT/ 700
MB SLY FLOW THAT YESTERDAY WAS CONFINED TO THE MID-ATLANTIC TO
EXPAND W TO INCLUDE THE OH VLY TODAY. AT THE SAME
TIME…HOWEVER…LITTLE CHANGE IS EXPECTED IN THE DEEP MOISTURE
FIELD…WITH PW VALUES AOA 2 INCHES REMAINING CONFINED TO AREAS E OF
THE APPALACHIANS FROM GA AND THE CAROLINAS NNE TO SRN NEW ENGLAND.

AS WAS THE CASE YESTERDAY…CLOUDS WILL LIMIT LOW-LVL
DESTABILIZATION OVER MUCH OF THE REGION…WITH THE GREATEST HEATING
EXPECTED E OF THE OH VLY UPR LOW…I.E. OVER PARTS OF TN…KY…AND
SRN IND/OH. DIURNAL STORMS IN THE LATTER REGION…FOCUSING ALONG AND
AHEAD OF ASSOCIATED SFC FRONT/TROUGH…COULD YIELD SVR HAIL AND
PERHAPS LOCALLY DMGG WIND GIVEN STRENGTH OF MID/UPR-LVL FLOW.

FARTHER E…SSW-NNE ORIENTED BANDS OF CONVECTION/EMBEDDED STORMS
APPEAR LIKELY WHERE POCKETS OF LOW-LVL HEATING OCCUR FROM GA AND THE
CAROLINAS NNE INTO NY/NEW ENGLAND. AN IDENTIFIABLE SHORTWAVE IMPULSE
IS NOT APPARENT ALONG THIS CORRIDOR THIS MORNING…IN CONTRAST TO
YESTERDAY. INDEED…WWD SHIFT OF ATLANTIC RIDGE SHOULD RESULT IN
RISING HEIGHTS ACROSS THE REGION. NEVERTHELESS…SLIGHTLY
CONFLUENT…VERY MOIST LOW-LVL FLOW IN THE PRESENCE OF
STRONGER-THAN-NORMAL MID/UPR LVL WINDS SUGGEST A CONDITIONAL RISK
FOR ISOLD DMGG WIND GUSTS AND/OR A BRIEF TORNADO OR TWO THROUGH
EARLY EVE.

…SRN RCKYS AND ADJACENT HIGH PLNS TODAY/TNGT…
SIMILAR TO YESTERDAY…MODERATE…DEEP NLY FLOW AT MID-LVLS AND
WEAK…DIURNALLY-DRIVEN UPSLOPE FLOW AT LWR LVLS SHOULD ONCE AGAIN
FOSTER AFTN STORM DEVELOPMENT OVER CO AND NM MOUNTAINS. MODEST
MOISTURE AVAILABILITY SHOULD SOMEWHAT LIMIT STORM
COVERAGE…ESPECIALLY IN CO…WHERE PW WILL REMAIN AOB .75 INCH.
SOMEWHAT GREATER MOISTURE WILL RESIDE IN NM…WHERE PW WILL REMAIN
AROUND 1 INCH WITH SFC DEWPOINTS IN THE UPR 50S/LWR 60S F. WITH 500
MB NLY WINDS AROUND 30 KTS…SUFFICIENT DEEP SHEAR WILL EXIST FOR
SUSTAINED/ORGANIZED STORMS. GIVEN STEEP LOW-LVL LAPSE RATES…THESE
MAY YIELD LOCALLY DMGG WIND AND ISOLD SVR HAIL AS THEY MERGE INTO A
SMALL CLUSTER OR TWO THROUGH EARLY TNGT.

…AZ THIS AFTN/EVE…
CURRENT CONVECTION/STORMS OVER SRN AZ WILL KEEP THE LWR DESERTS A
BIT MORE MOIST TODAY RELATIVE TO YESTERDAY. BUT CONDITIONS ALOFT AND
UPSTREAM /NNE/ACROSS UT AND THE FOUR CORNERS REGION WILL REMAIN
LARGELY UNCHANGED. SUFFICIENT MOISTURE /PW AROUND .75 INCH/ WILL BE
PRESENT FOR ANOTHER ROUND OF DIURNAL STORMS OVER THE HIGHER TERRAIN
OF AZ…BUT MOISTURE VALUES DO NOT APPEAR FAVORABLE FOR SUSTAINED
ACTIVITY/LARGE CLUSTERS SUCH AS THOSE THAT MIGHT ACCOMPANY A TRUE
MONSOON PATTERN. NEVERTHELESS…SATELLITE DOES SHOW WHAT APPEARS TO
BE AN UPR IMPULSE NOW ENTERING CNTRL UT THAT SHOULD BE
FAVORABLY-TIMED TO ENHANCE STORM DEVELOPMENT OVER THE AZ RIM COUNTRY
LATER TODAY. FORECAST WIND PROFILES SUGGEST THAT THIS ACTIVITY
SHOULD ONCE AGAIN MOVE/DEVELOP MAINLY SSWWD…WITH AN ASSOCIATED
RISK FOR ISOLD DMGG WIND GUSTS/LOCALIZED HABOOB CONDITIONS OVER THE
SE THIRD OF THE STATE.

…INTERIOR NORTHWEST/NRN INTERMOUNTAIN REGION THIS AFTN/EVE…
MID-LVL FLOW ON NW SIDE OF GRT BASIN RIDGE WILL VEER AND SLIGHTLY
STRENGTHEN LATER TODAY AS BC JET STREAM CONTINUES ENEWD. COUPLED
WITH STRONG SFC HEATING AND THE PRESENCE OF MODEST MOISTURE /PW AOA
.75 INCH/…SETUP MAY YIELD ISOLD TO WDLY SCTD AFTN TSTMS FROM NRN
CA AND WRN/NRN NV ENE INTO SRN/ERN ORE AND CNTRL/SRN ID. SOME OF THE
STORMS WILL BE CAPABLE OF STRONG DOWNDRAFTS AND POSSIBLY HAIL.

..CORFIDI/MOSIER.. 07/02/2013

DY1 SWODY1 06:02Z

0

VALID 021200Z – 031200Z

…NO SVR TSTM AREAS FORECAST…

…SYNOPSIS…
THE OVERALL AMPLIFIED LARGE SCALE PATTERN WILL FLUCTUATE LITTLE
DURING THE PERIOD. THE UPPER LOW OVER THE MIDWEST/LOWER OH VALLEY
WILL CONTINUE TO SLOWLY RETROGRADE WESTWARD…FLANKED BY A
BUILDING/WESTWARD-SHIFTING UPPER RIDGE OVER THE WESTERN ATLANTIC AND
A SLOW WESTWARD-TRANSITIONING UPPER RIDGE OVER THE GREAT BASIN.
SIMILAR TO THE PAST FEW DAYS…WHILE PARTICULARLY WIDESPREAD SEVERE
TSTMS ARE NOT EXPECTED…CORRIDORS OF SOMEWHAT STRONGER INSTABILITY
MAY COINCIDE WITH SUFFICIENT VERTICAL SHEAR FOR ISOLATED
STRONG/SEVERE TSTMS ACROSS PARTS OF THE APPALACHIANS/OH
VALLEY…SOUTHERN ROCKIES…AND THE INTERIOR NORTHWEST MAINLY THIS
AFTERNOON/EARLY EVENING.

…MIDWEST/OH VALLEY TO NEAR/EAST OF THE APPALACHIANS…
WEAK HEIGHT RISES ARE EXPECTED ESPECIALLY NEAR/EAST OF THE
APPALACHIANS AS THE UPPER LOW CONTINUES TO SHIFT WESTWARD OVER THE
LOWER OH VALLEY/MIDDLE MS VALLEY AND THE WESTERN ATLANTIC RIDGE
BUILDS. A VERY MOIST AIRMASS WILL NONETHELESS PERSIST/FOCUS A BIT
WESTWARD IN AREAS ALONG/EAST OF THE APPALACHIANS WITH NEAR/ABOVE 70
F SURFACE DEWPOINTS REMAINING QUITE COMMON.

PARALLEL TO THE STATIONARY/SLOW-MOVING PERSISTENT FRONTAL ZONE…A
BELT OF 30-40 KT SOUTH-SOUTHWESTERLY MID-LEVEL FLOW WILL EXIST OVER
MUCH OF THE REGION. AS HAS BEEN THE CASE…WEAK LAPSE RATES
ALOFT/MODEST OVERALL DESTABILIZATION WILL TEND TO LIMIT THE
SCOPE/EXTENT OF THE SEVERE RISK…ALTHOUGH POCKETS OF RELATIVELY
STRONGER HEATING/DESTABILIZATION WILL CONTRIBUTE TO THE POTENTIAL
FOR STORMS CAPABLE OF DOWNBURSTS/LOCALLY DAMAGING WINDS…AND
POSSIBLY SOME MARGINALLY SEVERE HAIL ACROSS THE MIDWEST/OH VALLEY
THIS AFTERNOON.

ALSO…IN SPITE OF THE GRADUALLY APPROACHING UPPER RIDGE/SURFACE
HIGH…THE MAGNITUDE OF THE LOW LEVEL WINDS /30+ KT WITHIN THE
LOWEST 1-2 KM/ AND ASSOCIATED SRH MAY ACCOUNT FOR RELATIVELY
WEAK/TRANSIENT SUPERCELLS CAPABLE OF A BRIEF TORNADO TODAY /THROUGH
AROUND SUNSET/ IN AREAS SUCH AS THE CAROLINAS/MID-ATLANTIC STATES
AND PERHAPS INTO PARTS OF THE NORTHEAST STATES.

…NM/SOUTHERN CO…
A RELATIVELY HIGH MOISTURE CONTENT AIRMASS AND OROGRAPHIC INFLUENCES
WILL LIKELY LEAD TO ANOTHER DAY OF SCATTERED TSTM DEVELOPMENT THIS
AFTERNOON FROM CENTRAL/SOUTHERN CO INTO A LARGE PART OF NM. A
MODERATELY STRONG BELT OF NORTHERLY FLOW ACROSS THE REGION WILL AID
IN SOME SUSTAINED MULTICELLS CAPABLE OF MARGINALLY SEVERE
HAIL…ASIDE FROM THE PROBABLE DEVELOPMENT OF SOUTH-SOUTHWESTWARD
MOVING CLUSTERS /CAPABLE OF LOCALLY DAMAGING WIND GUSTS/ ESPECIALLY
ACROSS NM BY LATE AFTERNOON/EARLY EVENING.

…AZ…
INITIALLY…STRONG/POSSIBLY SEVERE TSTMS CAPABLE OF HAIL ON AN
ISOLATED BASIS MAY DEVELOP OVER THE NORTHERN/EASTERN AZ MOUNTAINS
AND RIM VICINITY THIS AFTERNOON. AIDED BY A SLIGHT DEGREE OF COOLING
ALOFT AND A RIBBON OF MODERATE NORTH-NORTHEASTERLY MID-LEVEL WINDS
/20-25 KT/…SOME OF THESE STORMS SHOULD PROPAGATE INTO THE HOT
AIRMASS ON THE DESERT FLOOR OF SOUTHEAST/SOUTH-CENTRAL AZ WITH AN
ASSOCIATED DOWNBURST/SEVERE WIND GUST POTENTIAL THROUGH LATE
AFTERNOON/EARLY EVENING.

…INTERIOR NORTHWEST/NORTHERN INTERMOUNTAIN REGION…
A HOT/INCREASINGLY MOIST AIRMASS WILL RESIDE ON THE NORTH-NORTHWEST
FRINGES OF THE WESTERN STATES UPPER RIDGE…WHICH WILL FLATTEN A
DEGREE DURING THE LAST HALF OF THE PERIOD VIA A SHORTWAVE
TROUGH/SPEED MAX CROSSING BRITISH COLUMBIA. ISOLATED/WIDELY
SCATTERED TSTMS ARE EXPECTED TO DEVELOP/INCREASE DURING THE
AFTERNOON ACROSS PARTS OF NV/ADJACENT CA INTO ORE/ID. SOME OF THESE
STORMS WILL BE CAPABLE OF STRONG DOWNDRAFTS AND POSSIBLY SOME HAIL
/MAINLY ORE AND ID/.

..GUYER/LEITMAN.. 07/02/2013

DY1 SWODY1 01:02Z

0

VALID 020100Z – 021200Z

…NO SVR TSTM AREAS FORECAST…

…EASTERN CONUS…
A VERY MOIST AIRMASS WILL REMAIN ACROSS THE REGION WITH WIDELY
SCATTERED TO SCATTERED SHOWERS/TSTMS CONTINUING TONIGHT FROM THE OH
VALLEY TO PORTIONS OF THE EASTERN SEABOARD. BUT GIVEN LOSS OF
DAYTIME HEATING…SEVERE POTENTIAL IN THE FORM OF A LOCALLY DAMAGING
WIND GUST OR BRIEF TORNADO RISK SHOULD REMAIN QUITE MARGINAL THE
REMAINDER OF THE NIGHT.

…CO/NM AND SOUTHERN AZ…
AN ISOLATED STRONG STORM OR TWO CAPABLE OF HAIL MAY REMAIN POSSIBLE
MAINLY OVER THE NEXT HOUR OR TWO /MID-EVENING/ ACROSS EAST-CENTRAL
CO AND INTERIOR NM/MOUNTAINS OF SOUTHEAST AZ. LOCALLY DAMAGING WIND
GUSTS WILL BE POSSIBLE IN AREAS SUCH AS SOUTHERN NM THIS
EVENING…OR MORE SO SOUTHEAST AZ AS ISOLATED STORMS MOVE
SOUTHWESTWARD OFF THE HIGHER TERRAIN INTO A HOT BOUNDARY LAYER /100+
F SURFACE TEMPERATURES EARLY THIS EVENING ON THE DESERT FLOOR/.

..GUYER.. 07/02/2013

DY1 SWODY1 07:35Z

0

VALID 012000Z – 021200Z

…THERE IS A SLGT RISK OF SVR TSTMS KY…

VERY MINOR MODIFICATIONS ARE NEEDED FOR 20Z UPDATE CYCLE. LATEST
SATELLITE/RADAR IMAGERY SUPPORTS EARLIER THINKING REGARDING THE
UPWARD EVOLUTION OF CONVECTION AHEAD OF WEAK VORT MAX OVER THE TN/OH
VALLEY REGION. TSTMS ARE SLOWLY ORGANIZING ALONG AN ARCING BAND
FROM KY/TN BORDER…SEWD INTO ERN TN AND THIS ACTIVITY SHOULD
GRADUALLY LIFT NWD INTO KY WHERE MUCAPE IS AOA 2000 J/KG. LOCALLY
DAMAGING WINDS REMAIN POSSIBLE WITH THIS CONVECTION.

ELSEWHERE…ISOLATED-SCT TSTMS PERSIST ALONG THE ATLANTIC COAST FROM
FL TO NC WHICH COULD PRODUCE GUSTY WINDS AT TIMES.
OTHERWISE…STRONG HEATING ALONG THE PERIPHERY OF MID LEVEL
ANTICYCLONE IS CONTRIBUTING TO DEEPENING CONVECTION OVER THE HIGHER
TERRAIN FROM CO/NM INTO AZ. THIS ACTIVITY SHOULD GRADUALLY
INTENSIFY OVER THE NEXT FEW HOURS AND GUSTY WINDS MAY ACCOMPANY
THESE STORMS.

..DARROW.. 07/01/2013

.PREV DISCUSSION… /ISSUED 1128 AM CDT MON JUL 01 2013/

…SYNOPSIS…

A HIGH-AMPLITUDE PATTERN WILL CONTINUE THROUGH THE D1
PERIOD…FEATURING AN UPPER LOW NEAR THE CONFLUENCE OF THE MS AND OH
RIVERS AND AN ANTICYCLONE CENTERED OVER THE GREAT BASIN. A NUMBER
OF PERTURBATIONS WILL PIVOT AROUND THE UPPER LOW WITH A BAND OF
MODESTLY STRONG SLY TROPOSPHERIC FLOW MAINTAINED ALONG AND E OF A
SFC QUASI-STATIONARY BOUNDARY SITUATED ALONG THE APPALACHIANS.

…OH/TN VALLEYS THIS AFTERNOON AND EVENING…

MORNING VISIBLE SATELLITE IMAGERY SHOWS A LOCAL MINIMUM IN CLOUDS
ACROSS CNTRL/ERN KY INTO MIDDLE/ERN TN WHICH SHOULD ALLOW FOR STRONG
DIABATIC HEATING TO OCCUR. THIS AREA COINCIDES WITH A POCKET OF
RELATIVELY COOL MIDLEVEL TEMPERATURES /I.E. -12 TO -13 C AT 500 MB/
WHICH WILL CONTRIBUTE TO AIR MASS DESTABILIZATION THROUGH THE PEAK
OF THE DIURNAL HEATING CYCLE WHERE MLCAPE WILL APPROACH 1000-1500
J/KG. A VORTICITY MAXIMUM CURRENTLY OVER WRN TN/NRN MS WILL PIVOT
NEWD AROUND THE UPPER LOW TODAY FOSTERING SCATTERED TO NUMEROUS TSTM
DEVELOPMENT. THIS REGION WILL RESIDE ALONG THE WRN PERIPHERY OF
STRONGER DEEP-LAYER FLOW /AND SHEAR/ WITHIN ERN SEMI-CIRCLE OF ERN
U.S. TROUGH…RESULTING IN AN ENVIRONMENT FAVORABLE FOR A
POTENTIALLY MORE CONCENTRATED ZONE OF SEVERE STORMS. LARGE HAIL AND
LOCALLY DAMAGING WINDS WILL BE THE PRIMARY HAZARDS INTO THIS EVENING
BEFORE TSTMS WEAKEN WITH THE LOSS OF DAYTIME HEATING.

…ATLANTIC COASTAL STATES TODAY INTO THIS EVENING…

MORNING WATER VAPOR IMAGERY SHOWS A COUPLE OF LOW-AMPLITUDE
IMPULSES…ONE OVER THE CAROLINAS AND THE OTHER OVER THE NERN G.O.M.
WHICH WILL TRANSLATE NWD…ENHANCING DEEP ASCENT ACROSS A VERY MOIST
AND POTENTIALLY MODERATELY UNSTABLE WARM SECTOR. THIS WILL
CONTRIBUTE TO THE DEVELOPMENT OF SCATTERED TO NUMEROUS TSTMS BY
AFTERNOON ALONG AND E OF THE APPALACHIANS WITHIN A UNIDIRECTIONAL
AND MODESTLY SHEARED KINEMATIC ENVIRONMENT. SIMILAR TO SUNDAY…A
MIXTURE OF MARGINAL SUPERCELLS AND BOWING STRUCTURES WILL BE
POSSIBLE WITH A RISK FOR LOCALLY DAMAGING WINDS…SOME HAIL…AND
PERHAPS A BRIEF TORNADO.

…CNTRL/SRN ROCKIES AND ADJACENT SRN HIGH PLAINS INTO SRN AZ THIS
AFTERNOON INTO TONIGHT…

ONGOING N-S BAND OF ELEVATED TSTMS OVER ERN CO APPEARS TO BE
ASSOCIATED WITH A WEAK IMPULSE PROGRESSING SWD. FORCING FOR ASCENT
ATTENDANT TO THIS FEATURE COUPLED WITH STRENGTHENING TERRAIN-INDUCED
CIRCULATIONS WILL GIVE RISE TO SCATTERED TO NUMEROUS TSTMS ACROSS
THE REGION TODAY WITHIN AN ENVIRONMENT OF MODEST AMOUNTS OF
INSTABILITY AND VERTICAL SHEAR. GIVEN THE DEVELOPMENT OF A DEEP
WELL-MIXED PBL WITH SIZABLE T-TD SPREADS…LOCALLY DAMAGING WINDS
APPEAR TO BE THE PRIMARY HAZARD…THOUGH SOME HAIL WILL BE POSSIBLE
WITH THE STRONGEST UPDRAFTS.

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