Mesoscale Discussion 2149

Issued

Sep 7, 2011, 4:02 PM MST (23:02 UTC)

Expired

Sep 7, 2011, 6:00 PM MST

In force

118 min

Issued by

the Storm Prediction Center

Counties Cochise County, AZ, Gila County, AZ, Graham County, AZ, Greenlee County, AZ, Pinal County, AZ, Santa Cruz County, AZ, Catron County, NM, Doña Ana County, NM, Grant County, NM, Hidalgo County, NM, Luna County, NM, Sierra County, NM, Socorro County, NM

The Tucson radar (KEMX), 217 km from the middle of the area, began a volume at 23:03 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

838 
ACUS11 KWNS 072303
SWOMCD
SPC MCD 072302
NMZ000-AZZ000-080100-

MESOSCALE DISCUSSION 2149
NWS STORM PREDICTION CENTER NORMAN OK
0602 PM CDT WED SEP 07 2011

AREAS AFFECTED...SERN AZ...SWRN NM

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 072302Z - 080100Z

A FEW STRONG STORMS WILL BE POSSIBLE THROUGH THE EVENING.
HOWEVER...GIVEN THE SPORADIC/MARGINAL NATURE OF ANY SVR THREAT AND
LACK OF CONVECTIVE ORGANIZATION...A WW IS NOT NEEDED.

LATE AFTERNOON MESOANALYSIS DEPICTS A SFC FRONT EXTENDING FROM CNTRL
NM INTO CNTRL AZ AND MOVING SLOWLY SWD...AS A WSW-ENE-ELONGATED
MID-LEVEL IMPULSE /EVIDENT IN RECENT WATER VAPOR IMAGERY/ DRIFTS
ESEWD. FRONTAL CONVERGENCE...COMBINED WITH ASCENT OFFERED BY THE
IMPULSE AND OROGRAPHIC INFLUENCES...WILL CONTINUE TO SUPPORT
ISOLATED TO SCATTERED CONVECTION INTO THE EVENING. FURTHERMORE...A
FETCH OF MID/UPPER-LEVEL MOISTURE EAST OF A LOW-LATITUDE IMPULSE OFF
THE COAST OF BAJA CALIFORNIA...AUGMENTED BY SOME MONSOONAL
MOISTURE...WILL CONTINUE TO BE DRAWN INTO THE REGION TO AID IN A
THREAT FOR STORMS INTO THE EVENING.

THE STRONGEST CONVECTION WILL BE CONFINED TO AREAS INVOF THE
LOW-LEVEL MOISTURE AXIS POSITIONED TO THE NORTH OF THE FRONT IN NM
AND FAR ERN AZ. THIS AXIS ARCS SWD INTO PARTS OF S-CNTRL AZ TO THE E
OF A SFC THERMAL TROUGH OVER WRN AZ. SFC OBS DEPICT DEWPOINTS IN THE
50S COINCIDING WITH THE LOW-LEVEL MOISTURE AXIS...SUPPORTING MLCAPE
VALUES UP TO 1000 J/KG GIVEN 700-500-MB LAPSE RATES OF 7-8 C/KM.
THESE PARAMETERS COULD SUPPORT A FEW STRONG THUNDERSTORMS. GUSTY
WINDS WILL BE POSSIBLE SOUTH OF THE FRONT IN THE DEEPLY MIXED
BOUNDARY LAYER...AS SFC TEMPERATURE-DEWPOINT SPREADS OF NEARLY 50F
SUPPORT ENHANCED DOWNDRAFTS OWING TO SUB-CLOUD EVAPORATIVE COOLING.
AN ISOLATED INSTANCE OR TWO OF MARGINALLY SVR WINDS CANNOT BE RULED
OUT WITH THIS ACTIVITY. NORTH OF THE FRONT...WHERE SFC TEMPERATURES
ARE COOLER /THOUGH LOW-LEVEL MOISTURE IS RICHER/...SMALL HAIL CANNOT
BE RULED OUT. HOWEVER...THE THREAT FOR ORGANIZED CONVECTION AND SVR
STORMS WILL BE MITIGATED BY THE ABSENCE OF STRONGER DEEP-LAYER
SHEAR...AS AREA VWP DATA SUGGEST 0-6-KM BULK SHEAR VALUES LESS THAN
20 KT. STORMS ARE EXPECTED TO WEAKEN AFTER 02Z IN RESPONSE TO
DIABATIC COOLING.

..COHEN.. 09/07/2011

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...ABQ...EPZ...TWC...FGZ...PSR...

LAT...LON   33050569 32620603 31930755 31340864 31130972 31271094
            32461122 33461174 34241197 34551126 34520904 34620703
            33840570 33050569

Mesoscale Discussions in New Mexico, 2011Mesoscale Discussions in Arizona, 2011Every mesoscale discussion in 2011

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.