CASE 11 - Scattered convection over coastal plain

(Line to NE and scattered to SW over GOC)

7/22/04

Microphysical scans 2030 - 2245 Z, 2h 15m

(System lifetime: 1830 - 2245 Z)

SYNOPTIC CONDITIONS SUMMARY:

Synoptic feature map -

IOP status - IOP #3 in effect (see report). This IOP (0Z 7/20-0Z 7/23) captured the breakdown of a monsoon ridge over the domain, along with several wind surges over the GOC including a major Gulf Surge (GS#2). GS#2 initiated prior to this time period, from 10-18Z on 7/22, due to ouflow of a large quasi-linear MCS that stretched from Sonora to the S GOC. During this time period, GS#2 was waning. At 6Z on 7/23, GS#2 ramped up due to the outflow from an MCS that formed along the AZ, NM, Mexico border and moved out over the northern GOC.

IV#6 over central Mexico, well east of S-Pol domain.

Day 0 forecast discussion text

Winds

200 mb - model.ETA.200407230000.00_200mb_wnd.gif

500 mb - model.ETA.200407230000.00_500mb_wnd.gif

700 mb - model.ETA.200407230000.00_700mb_wnd.gif

850 mb - model.ETA.200407230000.00_850mb_wnd.gif

Mazatlan SkewT - ops.SkewT.200407221500.Mazatlan_MX.gif - ops.SkewT.200407222100.Mazatlan_MX.gif

EVENT SUMMARY: NW-SE oriented line to NE of S-Pol, along with scattered intense convection to SW over GOC.

24 h precipitation totals -

2024Z, GOES-10 Vis

S-POL SUMMARY: NOTE - may be interesting case to look at in terms of rainfall microphysics.

SCAN / DEVELOPMENT OVERVIEW:

1830-1930 Z	Cell <40 km SE of S-Pol is oriented N-S, parallel to low-level flow. This line loses fine structure by 1930Z. Time loop shows low-level boundary interactions in vicinity of S-Pol. 1830 Z, Base reflectivity. 1930Z, Base reflectivity.
2015 Z	NW-SE oriented convective line to the E of S-Pol. 2015 Z, Base reflectivity.
2030 Z	Begin Microphysical Scans, Switching to MicroNear135: Centered sector over NE quadrant. This was a tough decision as there was still convective activity to the SW over the GOC.
2145 Z	Cell ~30 km N has 60+ dBZ, Kdp ~ 3 deg/km, and S-Pol log suggests this is due to drops with ice cores that are possibly producing anomalously high phase shift for given reflectivity. Log also states that Zdr cross-sections not indicating much in the way of Zdr columns above freeze level - also no evidence of LDR cap.
2115 Z	Most of intense convective activity remains to NE, as opposed to that over GOC to SW. 2115 Z, Base reflectivity.
2154 Z	Running Profiler Sequence (2PPI, 2RHI): Convective line passed right over NOAA profiler, warranting scans. 2200 Z, Base reflectivity.
2245 Z	End Microphysical Scanning, Switching to ClimoNear: Convective activity waning.