CASE 7 - Mature stage MCS over SMO propagating over coastal plain

7/17/04

Microphysical scans 1000 - 1200 Z, 2h

(System lifetime: 0800 - 1400 Z)

SYNOPTIC CONDITIONS SUMMARY:

IOP status - No IOP called during this time.

200 mb ridge axis from central TX into southwestern CO provided favorable moisture flow from GOC and Gulf of Mexico.

Convergence boundary throughout northwest Mexico possessed cyclonic rotation over Sonora. Bddy aided in development of a major linear MCS along SMO, which persisted throughout day and into the night hours (north of S-Pol domain).

IV#5 over Baja.

Scattered severe storms produced heavy rainfall throughout region, particularly longer-lived cells.

Synoptic feature map -

Day 0 forecast discussion text

Winds

200 mb - model.ETA.200407171200.00_200mb_wnd.gif

500 mb - model.ETA.200407171200.00_500mb_wnd.gif

700 mb - model.ETA.200407171200.00_700mb_wnd.gif

850 mb - model.ETA.200407171200.00_850mb_wnd.gif

EVENT SUMMARY: A non-linear MCS developed over the SMO to the southeast of Mazatlan. This system developed after the linear MCS discussed in the Day 0 forecast for this day. As this later system matured, new cell growth occurred close to S-Pol. Overall, only the northernmost 1/4 of this MCS was within the S-Pol domain.

24 h precipitation totals -

TIMELINE OF DEVELOPMENT:

0800 Z	Convection initiates over SMO SE of S-Pol, beginning to intensify.
0800 - 1300 Z	Convective region growing and expanding westward over the GOC, developing into a mature MCS. Around 1139, MCS briefly (~ 30 min) takes on a quasi-linear structure as new convection develops to the NW and SE of main convective region. During this time, new cell development to NW of MCS was occurring near S-Pol.
1300 - 1400 Z	MCS dissipating.

S-POL SUMMARY: Northern tip of MCS, including a few intense cells, was captured by S-Pol microphysical scans.

S-Pol log - spol_071704.txt

1200Z, Base Reflectivity - S-Pol captures northwestern edge of MCS, with several cells forming close to S-Pol

SCAN OVERVIEW:

0957 Z	Begin Microphysical Scanning, Switching to MicroNear135: Before this time, the most intense cells were beyond 120 km SE of S-Pol. Small, less intense cells were popping up 20-40 km E of S-Pol. As the cells closer to S-Pol strengthened, microphysical scanning was initiated. It rained at S-Pol about 15 min prior to switch to microphysical scans.
1059 Z	Switching to MicroNear90:
1109 Z	Switching back to MicroNear135: 90 degree sectors were missing convection, and so opted for a wider sector.
1210 Z	End Microphysical Scans, Switching to ClimoFar: Cellular activity in vicinity of S-Pol diminishing, although MCS the the SE still looking good.