CASE 5 - Scattered
cells over SMO
Microphysical scans 2130 - 2300 Z, 1h
30m
SYNOPTIC CONDITIONS SUMMARY:
IOP status - No IOP called at this time (IOP
#2 ended 00Z on TS Blas was downgraded
to TD, moving out of Tier 1 domain. IV#5 over NW MX, moved
quicker to W than expected. This upper level trough passed over S-Pol
domain in the evening, around 00Z on Complicated flow pattern
exhibited over S-Pol domain - N/S oriented shear line located 50 mi east of
S-Pol separating NW flow to the west from NE flow to the east. In addition,
southerly flow was moving up along the shear line. Much of this flow
pattern can be confirmed by viewing the water vapor loop (available at http://www.joss.ucar.edu/cgi-bin/catalog/name/ops/date_browse?dateUTC=20040715).
Synoptic feature map
Day
0 forecast discussion text
Winds
200
mb - model.ETA.200407160000.00_200mb_wnd.gif
500
mb - model.ETA.200407160000.00_500mb_wnd.gif
700
mb - model.ETA.200407160000.00_700mb_wnd.gif
850
mb - model.ETA.200407160000.00_850mb_wnd.gif
EVENT SUMMARY: Cells formed off and on along shear line located 50 mi east of S-Pol (see
description in synoptic conditions
summary). Cells were intense and deep (60 dBZ and topping near 15-16 km).
Development along the shear line coincided with the passage of an upper level trough.
24
h precipitation totals -
TIMELINE
OF DEVELOPMENT:
|
2100 Z |
The previous 2 h, scattered echoes
of reasonable intensity (60 dBZ, tops 15-16 km) were observed developing over
the SMO (~ 80-100 km range) and propagating westward. At 2100, new
development was observed at 40 km due east of S-Pol, in the vicinity of the
N/S oriented shear line. New development appeared to run in a short (~15-20
km) N/S oriented line with very slow westward motion. 2100Z,
Base reflectivity
|
|
2200 Z |
As previous cells weakened, new
cells once again developed in the vicinity of the shear-line. 2200Z,
Base reflectivity
|
|
2230 Z |
Cells appeared to be dissipating. |
S-POL SUMMARY:
SPECIAL
NOTES: Cells had extensive anvils to E, despite strong easterly flow aloft -
suggests very inefficient precipitation processes. Ascertaining the role of
shear line in these two developments might prove interesting.
S-Pol
log - spol_071504.txt
2124 Z, GOES-10
|
|
|
SCAN
SUMMARY:
|
1900
- 2130 Z |
Running ClimoFar: Watching scattered cells initiating over SMO. |
|
2130
Z |
Begin Microphysical Scanning, Running
MicroNear135: New cell growth at 40
km E - in vicinity of a N/S oriented shear line. Cell initiation/growth
mechanism may be related to shear line. Also, upper level trough was over the
area at the time, which also may have contributed to development. |
|
2200
Z |
New
group of cells initiating at 40 km east - previous cells have advected to the
west and are dissipating. |
|
2245
Z |
Running MicroFar135: Changed in order to improve the vertical
resolution. Cells at 30 km east are not being topped, but they are mostly anvil
at upper levels so trade-off seems worth it. |
|
2300
Z |
End Microphysical Scanning: Went back to ClimoFar because most cell activity
has dissipated. |