orographic precipitation in potentially unstable alpine storms: map iops 2b, 3, and 5
DESCRIPTION
Orographic Precipitation in Potentially Unstable Alpine Storms: MAP IOPs 2b, 3, and 5 Socorro Medina and Robert A. Houze. Lago Maggiore region. IOP2b. Equivalent Potential Temperature. IOP2b. 12Z 20 Sep 99. Milan sounding. MAP IOP2b 33-hour Mean Radial velocity. NNW. S-Pol radar. - PowerPoint PPT PresentationTRANSCRIPT
Orographic Precipitation in Potentially Unstable Alpine Storms:
MAP IOPs 2b, 3, and 5
Socorro Medina and Robert A. Houze
Lago Maggiore region
IOP2b
Equivalent Potential Temperature
IOP2b
Milan sounding
12Z 20 Sep 99
MAP IOP2b33-hour Mean Radial velocity
S-Pol radar
NNW
MAP IOP2b33-hour Mean Reflectivity
S-Pol radar
NNW
MAP IOP2bFrequency of occurrence of particle types
accumulated over 33 Hours
S-Pol radar
NNW
graupel (2% contour) melting snow (30% contours)
weak echo snow (50% contour)
ALPS
snow
rain
0ºC
cloud dropletsgraupel growingby riming
rain growingby coalescence
Slightly unstable
air
Medina and Houze 2003
MAP Conceptual Model for precipitation enhancement inPotentially Unstable Upstream Conditions
Other potentially unstable upstream flow cases: MAP IOPs 3 and 5
IOP3
IOP5
Equivalent Potential Temperature
IOP3
Milan sounding
00Z 26 Sep 99
Equivalent Potential Temperature
Milan sounding
IOP3
00Z 26 Sep 99
IOP5
12Z 03 Oct 99
MAP IOP324-hour Mean Reflectivity
S-Pol radar
NNW
MAP IOP54-hour Mean Reflectivity
S-Pol radar
NNE
S-Pol radar
MAP IOP324-hour Mean Radial velocity
NNW
S-Pol radar
MAP IOP54-hour Mean Radial velocity
NNE
S-Pol radar
MAP IOP3Frequency of occurrence of particle types
accumulated over 24 Hours
NNW
graupel (2% contour) melting snow ( 3% contours)
weak echo snow (10% contour)
S-Pol radar
MAP IOP5Frequency of occurrence of particle types
accumulated over 4 Hours
NNE
graupel (5% contour) melting snow (10% contours)
weak echo snow (50% contour)
CONCLUSION
• Despite differences in the upper-level flow direction, the lower slope precipitation processes were similar in 3 IOPs.
• The observations were consistent with the conceptual model for potentially unstable upstream flow.
• Convective cells formed intermittently on the first major peak of terrain as a radial velocity jet rose over it.
• Both riming and coalescence were key microphysical processes in the cells.
Mixed case:MAP IOP 14
Equivalent Potential Temperature
IOP14
Milan sounding
00Z 4 Nov 99
MAP IOP14Mean wind shear from Lonate profiler
Mean and SD over 16 hours
MAP IOP1434-hour Mean Reflectivity
S-Pol radar
NNW
MAP IOP1434-hour Mean radial velocity
S-Pol radar
NNW
MAP IOP14Polarimetric Particle Identification over 34 Hours
weak echo snow (low dBZ, low ZDR)large aggregates and/or graupel (high dBZ, low ZDR)melting aggregates (high dBZ, high ZDR)
S-Pol radar
NNW
MAP IOP14Reflectivity from vertically pointing S-band radar
at Locarno Monti
Time UTC
Hei
ght
(km
)
OPRA radar