the april 28, 2011 severe weather and flash flood event
DESCRIPTION
The April 28, 2011 Severe Weather and Flash Flood Event. Mike Evans / NWS Binghamton, NY. Outline. Large-scale pattern / meso -analysis Radar data High resolution model output Summary. 500 mb heights and vorticity. Surface plot – 09z. - PowerPoint PPT PresentationTRANSCRIPT
The April 28, 2011 Severe Weather and Flash Flood Event
Mike Evans / NWS Binghamton, NY
Outline
Large-scale pattern / meso-analysisRadar dataHigh resolution model outputSummary
500 mb heights and vorticity
Surface plot – 09z
Equivalent potential temperature, omega and wind speed cross section – 12z
SPC surface and 700 mb frontogenesis – 09z
SREF CAPE and 850 hPa wind
SPC analysis 0-1 km shear and significant tornado parameter
SPC Guidance
Reflectivity and storm relative motion 0522 – 0540 UTC
Reflectivity and storm relative motion 0654 – 0830 UTC
Reflectivity and storm relative motion 0945 UTC
13
T-9 T-8 T-7 T-6 T-5 T-4 T-3 T-2 T-1 T-000.10.20.30.40.50.60.70.80.9
1
Verified Median NROT (Supercell tornadoes; Tim Humphrey)
.5 NROT
.9 NROT1.4 NROT1.9 NROT
NR
OT
14
T-5 T-4 T-3 T-2 T-1 T-00
0.2
0.4
0.6
0.8
1
1.2
Verified Median NROT (QLCS tornadoes; Tim Humphrey)
.5 NROT
.9 NROT1.4 NROT1.9 NROT
NR
OT
Normalized rotation – Erin tornado (QLCS)
Normalized rotation – Danby tornado(QLCS – broken S)
Normalized rotation – Pharsalia tornado (mini-supercell)
Normalized rotation – McDonough tornado (mini-supercell; range folding)
Normalized rotation – Columbus tornado (mini-supercell; RFD spin-up)
Normalized rotation – Herrick tornado(QLCS)
Severe reports
BGM CWA tornado climatology
High resolution model 1 km AGL reflectivity – valid 09z
High resolution model 1 km AGL reflectivity – valid 12z
HRRR 1 km AGL reflectivity valid 08z
SummaryTornadoes and flash floods affected central
New York and northeast Pennsylvania during the early morning on the 28th.
This was only the 2nd time since the late 1990s that a tornado was reported in our area between midnight and 9 am.
Tornadoes occurred with a variety of convective storm structures and a variety of rotational evolution patterns.
Summary continued00z hi resolution model runs forecast a
variety of structures; mostly broken lines of convection, composed of small line segments and some individual cells.
The 00z HRRR model was too weak with the line (especially over NY), but subsequent runs trended toward a better forecast.
All of the 00z models were too far west (too slow) with the convection from 06z through 12z.