CASE 4 - Irregularly
shaped MCS (land -> ocean)
Microphysical scans 1000 - 1500 Z, 5h
(System lifetime: 0500 - 1600 Z)
SYNOPTIC CONDITIONS SUMMARY:
Synoptic
feature map -
IOP status - This
was during IOP2, the first IOP to capture a minor Gulf Surge (see report here).
This day is noteworthy because it was the first day of the EOP that this
type of MCS (develops over the SMO and then moves offshore) was observed. TD3E (soon TS Blas) was
strengthening to S. Inverted trough (IV #4) was
moving in from E from center of MX, bringing moisture up from TD3E to help
fuel observed MCS. Midlevel winds were
strongly easterly, which was responsible for MCSs westward motion.
Day
0 forecast discussion text
Winds
200
mb - model.ETA.200407121200.00_200mb_wnd.gif
500
mb - model.ETA.200407121200.00_500mb_wnd.gif
700
mb - model.ETA.200407121200.00_700mb_wnd.gif
850
mb - model.ETA.200407121200.00_850mb_wnd.gif
EVENT SUMMARY: Irregularly-shaped MCS initiated over the SMO to the S/SE of
0954Z, GOES-10 Thermal IR
24
h precipitation totals -
TIMELINE OF DEVELOPMENT:
|
0300
Z |
Convection observed
developing over the SMO, approx. halfway between |
|
0500
Z |
Convective region
showing increased organization. |
|
0800
Z |
System expanding
offshore, and appears to consist of 2 multicellular components. System is
just S of Mazatlan. Most of the complex is still outside S-POL domain at this
time. |
|
1000
Z |
MCS
intensity peaking. S-Pol log notes significant lightning with this
storm. |
|
1400
Z |
MCS
has decayed
significantly. |
|
1430
Z |
Small,
secondary convective flare-up
occurs just N of Mazatlan, lasts ~ 1.5 h. It is unclear whether or not this
flare-up is directly related to MCS to the S. |
S-POL SUMMARY: S-Pol caught the northern portion of this MCS. The northern portion of
the system, including a few intense but shallow cells, were in range of S-Pol
as they moved offshore. MCS reached its peak at around 1000Z, which marks the
beginning of microphysical scans. A cell to the W/NW of S-Pol took on a bow
shape at the end of the observation period (~1445 Z).
S-Pol
log - spol_071204.txt
1000Z, Base reflectivity
SCAN OVERVIEW:
|
0500
- 0850 Z |
Running ClimoFar/ClimoShallow: There is scattered convection to the SE (0530), which has
initiated over SMO and is moving out over the GOC. Cells are shallow and pretty
far away. About 0800,
the northern portion of the larger system moves into the SE quadrant of the
S-Pol scope but remains quite far away (0830). Around 0900, some cells
observed to have 60+ dBZ in cores. |
|
0850
- 0910 Z |
Ad-hoc RHIs: Through various cells (140, 120, 125). RHIs show
cells are shallow and not very impressive. Continued in ClimoFar mode. |
|
1000
- 1200 Z |
Begin Microphysical Scans - Ad-hoc
PPIs: System is looking
well-defined (see image above). |
|
1200
- 1330 Z |
Running MicroNear: Switched PRF to 960 Hz. Centered 135 degree sector
scans on system (1200)
as it tracked from W to E, out over the GOC. Switched to MicroFar at 1330, as the
only significant convection is at 270-300 deg, 60-80 km. |
|
1330
- 1500 Z |
Running MicroFar: Only significant convection is at 270-300 deg,
60-80 km. At 1430, convection to the W over GOC has Kdp ~ 1/2, dφ/dr ~
2.5 deg/km, RR ~ 125 mm/hr, 60 dBZ to 8-10 km. At 1450, a cell at
296 deg / 120 km is taking on a bowed shape. Scan at 1500 shows Core
has definitely bowed with accelerated rear inflow clearly evident. |
|
1500
Z |
End Microphysical Scans: . At this time, convective activity has moved
beyond S-Pol domain. |
