15 June 2009 Severe Weather Outbreak Preliminary images

(Click on any image to see loop or larger image)

 

Meteorological Overview

 

Event Background:

Another big hail event almost exactly to the date of last year's big hailer -- June 16, 2008. For these parts (ALY CWA), was impressive with 23 severe thunderstorm warnings, 4 flash flood warnings, 39 severe reports, and 4 flash flood reports, and lasting 8+ hours.

Meteorology:

1. Off 12Z ALB sounding (image below), these parameters were noted...

a. Low WBZ -- 7075 ft ASL (climo is 8500 ft)

b. Afternoon CAPE projected at 1060 J/Kg on 73/53.

c. Light winds from 500mb to surface (500mb winds 20 kts. Less to the surface.)

d. Given these parameters, expected convective mode was pulse storms.

2. LAPS CAPE analysis showed significantly higher CAPE during the event than projected by 12Z morning ALY sounding. Widespread max LAPS CAPE was noted at 1600-2000 j/kg for much of the event preceding severe weather.

 

Selected anonymous meteorological discussions from CSTAR and MAP

 

>Quite the small-scale local hailstorm that rolled into the region from the NW near 2200 UTC 15 June 2009. I noticed that the sky had a bit of a greenish twinge as I was walking out to the parking lot at school around 2200 UTC. I encountered sudden hail going westbound on the Washington Avenue Extension and had to pull of the road adjacent to the Italian American Community Center. Hail (mostly soft) piled up to 5 cm deep on the road and grass. My car was covered with hail and the car windows frosted over as the car thermometer reported a temperature decrease to 9.4 C (I'm not sure I believe this reading). From the Italian American Community Center westward to Rt. 155 a thick hail fog developed over the hail-covered road and ground with visibility near zero in spots. The rapid hail fall combined with 35-40 kt wind gusts stripped lots of leaves off the trees.

 

 

>It looks to me as if the storm was a right-mover based on the radar loop. Right over Albany, that storm "collided" with eastward-moving convection that recently experienced a slight energy boost from the outflow boundary that you can see traveling SW in the 21z-22z timeframe.
 
 
>It is also interesting to note that the hail outbreak of June 15 occurred just one day earlier than the major hail outbreak of last year (June 16) over New York State and the Albany area associated with a cutoff cyclone. Both cases involved potent vorticity maxima and strong midlevel lapse rates. I attached plots (using 0.5 deg GFS) of lapse rates with standardized anomalies shaded. Both cases are clearly anomalous in terms of lapse rates, while last year's episode yielded several more hail reports and had greater areal coverage of >7 C/km lapse rates.
 
 
>The attached plot of CAPE and shear for the 6-15-09 case shows moderate CAPE over the Hudson Valley and western New England. I don't know if your office forecasted this 1500 J/kg CAPE near Albany, but it was obviously more localized than in the 6-16-08 case, which led to a smaller area of reports. Also noticeable in the 6-15-09 case are the weak shear and midlevel winds, which is along the lines with the slow-moving nature of these storms.
 
 
>Our local Maglenta severe weather checklist indicated a maximum hail size of 1/4" with the most unstable parameters we could come up with based on the morning soundings last Monday 15 June, so we weren't expecting such a significant hail event.  We do need to look at the deep steering flow, as the winds from the surface through at least 10,000 feet were 20 kt or less, suggesting relatively slow moving storms, which might tip us off that any non-severe or marginally severe hail or rain could add up to unusual amounts, but again, we'll have to look at that more closely.
 
 
>I am not convinced the June 15th case qualifies as a warm season "closed/cutoff" low.  The H500 trough remained relatively open based on the 12Z 15 June and 00Z June 16 observational data analyses I looked at.  It is possible it was closed off very, very briefly.  The 16 June 2008 cutoff is a "bear" compared to the latest one in terms of the amount of deep shear involved...and where the cut-off was located.  The instability (surface based or mixed layer) was much more robust.   The Maglenta Equation/Index is CONDITIONAL based on observational or model point soundings for the following parameters (SBCAPE, EHI, 0-3 km helicity, Max Sounding Wind, cell motion).  It doesn't take into account lapse rate values (h850-500; h700-500, etc,) and wet bulb zero heights, etc. The value can be a poor conditional indicator when dealing with unorganized or "loosely" organized convection. My guess is that the instability would drive the Maglenta index this day...and perhaps an 18Z sounding may have better captured it.   It looked like the environment on 15 June 2009 was a "Pulse" thunderstorm environment...where some boundaries where left around...and a major cell merger occurred over the Capital District with on tremendous hail swathe in parts of the region.   The cell merger looked like the biggest show of the day. 


 
I don't recall the precipitable water anomalies being that great this day.  I think the values indicated were about an inch.  It is interesting that the 700 hPa flow was from the northwest at around 15 kts.  I am interested in looking at the radar data thoroughly for this day sometime.  I am most interested on the cell merger over the Capital Region.
 

 

>The mode of convection was multi-cellular  with isolated supercells on 16 June 2008 that formed into lines/clusters.  Eventually, a line echo wave pattern formed too.  I think the Maglenta index conservatively was calculated to be 0.75" to 1.25" on 16 June 2008 by Brian F. and I.  We ended up having quite a few golfball to even a few 2" hail reports!!!  I wonder if the LAPS sounding better handled the CAPE on 15 June 2009 similar to what Matt shows below. The mode of convection on 15 June 2009 looks to be "Pulse", but perhaps stronger updrafts were supported when boundary/cell merging was done.

 

 

>I had the KENX VAD Wind profile running on AWIPS that day and for a good part of the day the max winds in the column were <= 15 KTS. I think there is definitely something to the lapse rates and the light winds in the vertical. The low wet bulb zero allowed hail to reach the surface very easily.

I'm also still impressed by the rainfall rates that day as well. We had numerous reports of 4 to 6 inches of rain in a half hour or less. Radar loops backed up the duration of rainfall. Our spotter in northern Washington County said 6 inches of rain fell in his gage in a half hour. Looking at the radar loop...the cell was over the area 20-25 minutes. In any event that's at least a 12 inch per hour rainfall rate from a non-tropical environment.

 

 

>In an early assessment this looks like a very anomalous "outlier" event in term of the numbers of warnings/verification in a fairly concentrated area  that occurred for a small closed low (I wouldn't say cut-off through multiple levels) for barely 12 hours or less based on what the NAM/GFS tried to show. Always room for improvement on both ends...and the atmosphere can always do interesting things that we can learn from.   I would guess 9 times out of 10 this situation would yield MAINLY sub-severe hail (less than 0.75"...or next year less than one inch).  It is interesting that the number of hail reports an inch or greater were only 14...and about half were multiple reports on the same cell/warning polygon...so this type of event may be even more infrequent. I think we also have to look at the hail equation article from George and Ken.  I am sure there were outlier cases that didn't jive well with the Index (I recall variable results in the wet-bulb zero heights). It doesn't take into account actual lapse rates...and things can change dramatically between 12Z-18Z.

 

 

>Past research showed the ideal wet-bulb zero height to be 7-9 kft for large hail in the Hail Index/Hail Size...interesting we were barely hitting the lower end of this threshold.  I saw this in your wiki-report.  However the FZL level height was around 8.5 kft.  I wonder if the wet bulb zero height being a tad higher coupled with the abundant SBCAPE of 1500-2000 J/kg , as Ray or someone if this alluded too.

I plugged these numbers into the Hail Index/Hail Size and it came up with:
EL= 30 kft
WBZ Height= 7,000
Total Totals=50
CAPE=2000 (went with the high end of the LAPS data)
SRH (0-3 km) = 2
H850 temps= 8C

It came up with a Minor Event and a Hail size of 0.66.  The 0-3 km shear is completely negligible.  I actually hand calculated the value and compared to the program output and I came up with the same hail size (I gave the wet bulb zero height a value of 2 based on the NWA paper).

Very interesting how much larger the hail stones were!  Again, this case is likely a fascinating outlier!

 

Satellite loops

 

Water Vapor Note the upper low tracking across the region

 

 

Visible loop Note the cyclonic vorticity and multiple bands of convection

 

 

Radar Loops

 

KENX Loop of reflectivity and radar detected hail

 

 

KENX Loop from 1540-1800 UTC of reflectivity and Severe Thunderstorm Warning Polygons

 

 

KENX Loop from 1800-2100 UTC of reflectivity and Severe Thunderstorm Warning Polygons

 

 

KENX Loop from 2100-2400 UTC of reflectivity and Severe Thunderstorm Warning Polygons

 

 

KENX Loop of the southern NY and northern NJ reflectivity and Severe Thunderstorm Warning Polygons Note the high 60+ dBZ reflectivities above 12,000 Feet in the slow moving thunderstorms that produced accumulating hail in southern NY and northern NJ.

 

 

Hail Swaths in central NY

 

 

Hail Swaths in southern NY and northern NJ

 

 

12Z 15 June Soundings

 

 

ALY BUF WMW

 

 

Lapse Rate Anomaly Graphic

 

 

Storm Prediction Center Outlook

 

 

Albany Area Forecast Discussions

 

 

Warnings and Severe Weather Reports

 

 

Another perspective of severe weather reports for individual NWS offices, courtesy of The Iowa Environmental Mesonet division of Iowa State University Department of Agronomy

 

NWS Albany, NY

 

 

NWS Binghamton, NY

 

 

NWS Burlington, VT

 

 

NWS Taunton, MA

 

 

NWS Upton, NY

 

 

Pictures Thanks to WTEN and WRGB Albany, NY and NWS Albany, NY Skywarn Spotters for Pictures Check back for more as we receive them.

 

Shelf cloud over Albany, NY

 

 

Pictures from Chatham, NY

 

 

Assorted hail pictures courtesy of Brian and Barbara Montgomery of Niskayuna

 

 

 

More Pictures from the Capital Region

 

 

Photos from Guilderland Courtesy of Tom and Alicia Wasula

 

 

 

Photos from UAlbany and Guilderland Courtesy of Ross Lazear

 

 

 

 

Pictures from Albany courtesy of Karen Taylor

 

 

 

Pictures from Schenectady courtesy of Andrew Roberts

 

 

Pictures of the approaching storm in Latham, and hail in Guilderland and Westmere, courtesy of Sean Organ

 

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Pictures from Galway Lake courtesy of Jason Satas

 

 

 

Pictures from Bennington, VT courtesy of Zach Manganello

 

 

 

Pictures from Hunter Mountain courtesy of John Parslow Jr.

 

 

Photos submitted from the WTEN Albany, NY Weather Center Spotters

 

Albany, NY

 

 

 

 

Ames, NY

 

Burnt Hills, NY

 

 

Galway, NY

 

 

 

Ghent, NY The storm approaching

 

 

Glenville, NY

 

 

 

Greenfield Center, NY

 

 

Albany, NY and Guilderland, NY

 

 

 

 

 

 

 

 

Kerhonkson, NY

 

 

New Baltimore, NY

 

 

Niskayuna, NY

 

 

 

Pittsfield, MA

 

 

Saratoga, NY

 

Valatie, NY

 

 

Rainbows from departing storms from Ballston Spa, NY

 

 

Approaching storm and departing storm with rainbow at Saratoga Lake, NY and Riley Cove at Saratoga Lake, NY

 

Pictures Courtesy of NWS Upton, NY Skywarn Spotters

 

Emerson Township, NJ

 

 

Washington Township, NJ

 

 

Videos are in different formats and are not posted here yet, until a common format can be established

 

Any questions or suggestions, please e-mail Neil.Stuart@noaa.gov