|
This web page contains background info on how I became familiar with radar
rainfall conversion and is no longer updated. Info includes DBZ Rainfall rates,
Wunderground weather stations, and what can go wrong does. Or to quote from a
man of experience, Cousin Woodman, "Good judgment comes from experience, and
experience -- well, that comes from poor judgment." ...in spades.
The following page
links
have rainfall comparisons that I am currently updating:
Current Rainfall Comparisons
Snowfall
Snowpack Snowmelt Comparisons
Runoff Comparison
in Las Vegas, NV
Runoff Comparisons
in Arizona
ET and Rainfall along
the Lower Colorado River, AZ-CA
Primary directive... never trust reported rain gage data
(and pilots). Look
at the time steps, sharpness of rain spikes, minimum windspeed, and completeness
of all parameters to gauge how carelessly stupid the provider is. This means airports are
usually off the menu to start. Airports only service pilots and we are not dumb
enough to want to fly in the rain. Wundergages that start with "K" are usually alot better
than those that start with "M". Irratic time steps are not a deal killer but if
possible find another gage. Compare annual rainfall totals for other nearby
Wundergages and pick the highest... something I did not do and you should. As it
turns out, I would say your NEXRAD computed
rainfall is probably better than 50% to 80% of Wundergages. Live and learn... or
believe me, I have flown these unfriendly skies. Those that
consciencentiously make the effort to provide a good rainfall record are a
credit to the human race... unlike some pilots at airports. ;-)
My critique here only applies to reported rainfall... temperature, humidity, and
windspeed is something even pilots can usually report accurately. I hope. ;-)
****************************
...Testing... Testing... Let's see how NEXRAD works for computing
rainfall in real-time at real-time rain gages, really.
(NOAA's Summary
here a must read.)
The first half of the this web page is what I went through getting my feet wet
with the ins and outs of NEXRAD radar and the quirks of Wunderground rain
gages. This part will be interesting to follow if you are a newbie to this stuff
like I am and a good laugh for you experts. The second half of this web page is
where my on going NEXRAD vs Tipping Bucket comparisons are shown in a more
concise graphical format. The tipping bucket rain
gages are located at:
1) Fort Lauderdale, Fl
2) Dallas, Tx
3) Collinsville, TX
4) Groveland, Ca (northern San Joaquin Valley foot hills)
5) Buck Meadows, Ca (northern San Joaquin Valley foot hills)
6) Tracy, Ca (northern San Joaquin Valley)
7) McFarland, Ca (southern San Joaquin Valley)
8) My Plastic Gage, Southern Nevada
9) USGS Diamond Creek Gage, AZ (Canyon Lands northwest AZ)
10) USGS Big Sandy River Gage, AZ (Sonoran Desert west central AZ)
11) USGS Santa Maria River Gage, AZ (Sonoran Desert west central AZ)
12) Wundergage Camp Wood, AZ (Upper Sonora west central AZ)
13) Additional comparisons for winter snowfall and radar performance discussions
can be seen
here.
You might ask why all my sites are located in the southern US. Well, I did not
know that NEXRAD radar worked when it snowed... live and learn (those are some
smart guys at NEXRAD headquarters!). I have now added
comparisons
with snow water content gauges in the western Sierra Nevadas that doesn't
make those guys at headquarters look to smart after all. Additionally, NEXRAD comparisons with a
professional network of tipping buckets are on my
Rainfall-Runoff Comparisons web page for
Las Vegas Valley, Nv.
Fit
the First (Oy Vey)
The Bellman looked uffish, and wrinkled his brow.
"If only you'd spoken before!
It's excessively awkward to mention it now,
With the Snark, so to speak, at the door!
"We should all of us grieve, as you well may believe,
If you never were met with again--
But surely, my man, when the voyage began,
You might have suggested it then?
"It's excessively awkward to mention it now--
As I think I've already remarked."
And the man they called "Carson!" replied, with a sigh,
"I informed you the day we embarked.
"You may charge me with murder--or want of sense--
(We are all of us weak at times):
But the slightest approach to a false pretense
Was never among my crimes!
"I said it in Hebrew--I said it in Dutch--
I said it in German and Greek:
But I wholly forgot (and it vexes me much)
That English is what you speak!"
"What's the good of Mercator's North Poles and Equators,
Tropics, Zones, and Meridian Lines?"
So the Bellman would cry: and the crew would reply
"They are merely conventional signs!
"Other maps are such shapes, with their islands and capes!
But we've got our brave Captain to thank:
(So the crew would protest) "that he's bought us the best--
A perfect and absolute blank!"
This was charming, no doubt; but they shortly found out
That the Captain they trusted so well
Had only one notion for crossing the ocean,
And that was to tingle his bell.
Let the Snark Hunt begin. ;-)
A storm moved through the KFLCORAL5 weather station area today (June 8, 09) and
the N0R and NCR correlated well with the weather station reported total rainfall
amount. The N1P 1-hour total had a
bug that has been fixed and is now available for download.
WunderG
Nexrad Nexrad
Date
KFLCORAL5 N0R NCR
6/8/2009 15:00
0.1042
0
0.00694
6/8/2009 16:00
0.0258
0
0.01111
6/8/2009 17:00
0
0 0.01042
6/8/2009 18:00
0.1312
0.60416 0.43055
6/8/2009 19:00
0.486
0.06919 0.16966
6/8/2009 20:00
0.0025
0.00417 0.06765
TOTAL
0.7497
0.67752 0.69633
The above graph of the 5-minute rainfall amounts paint a different picture.
Although the N0R and NCR values agree, their distribution is certainly different
than those reported by the weather station. Perhaps the rain fell as hail and
had to melt to be recorded by the weather station??? Hence it's even
distribution that seems odd for a rapidly moving thunderstorm.
The Fort Lauderdale airport National Weather Service located about 15 miles down
wind from our Wunder gage reported:
6:03 PM,N/A,,Overcast
6:28 PM,0.17,Rain
6:33 PM,0.19,Rain
6:37 PM,0.19,Rain
6:53 PM,0.19,Rain
7:53 PM,0.00,Rain
Total = 0.74
I quess the NWS can melt hail faster?
If anyone is following along I switched to this new rain gage. It agrees with
the results for the gage above, but it appears even better maintained.
New Wunderground Weather Station:
KFLPARKL4
New Boundary file:
Edited for better square Area1 X,Y Coordinates (pix)
322, 184
322, 186
324, 186
324, 184
322, 184
Xmin 322, Ymin 184, Xmax 324, Ymax 186
Area1= 2.20 (pix^2), Perimeter= 7.17 (pix), Centroid= 323, 185
New Point file:
323,185,323,185
1
Another Comaprison... Similar results:.
My method used for the N1P 5-minute values in the tables below were computed as
the change in the Nexrad values and has been subsequently abandoned because of
its unreliable results. The N1P is now simply the the N1P value as a 1 hour rate
just like N0R and NCR which means it lags and averages the rainfall record over
an hour period... which is fine for larger basins and IF the N1P wasn't so lousy
anyway!
|
13-Jun-09
|
5-minute
|
5-minute
|
5-minute
|
5-minute
|
Total
|
Total
|
Total
|
Total
|
|
|
WunderG
|
NEXRAD
|
NEXRAD
|
NEXRAD
|
WunderG
|
NEXRAD
|
NEXRAD
|
NEXRAD
|
|
Date
|
KFLPARKL4
|
N0R
|
NCR
|
N1P
|
KFLPARKL4
|
N0R
|
NCR
|
N1P
|
|
3:00 PM
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
3:05 PM
|
0
|
0
|
0.04167
|
0
|
0
|
0
|
0.04167
|
0
|
|
3:10 PM
|
0
|
0
|
0.125
|
0
|
0
|
0
|
0.16667
|
0
|
|
3:15 PM
|
0
|
0
|
0.125
|
0
|
0
|
0
|
0.29167
|
0
|
|
3:20 PM
|
0
|
0
|
0.125
|
0
|
0
|
0
|
0.41667
|
0
|
|
3:25 PM
|
0
|
0
|
0.00417
|
0
|
0
|
0
|
0.42084
|
0
|
|
3:30 PM
|
0
|
0
|
0.0075
|
0
|
0
|
0
|
0.42834
|
0
|
|
3:35 PM
|
0
|
0
|
0.02083
|
0
|
0
|
0
|
0.44917
|
0
|
|
3:40 PM
|
0
|
0.00417
|
0.0625
|
0
|
0
|
0.00417
|
0.51167
|
0
|
|
3:45 PM
|
0.00167
|
0.01167
|
0.04167
|
0
|
0.00167
|
0.01584
|
0.55334
|
0
|
|
3:50 PM
|
0.00667
|
0.0625
|
0.125
|
0
|
0.00834
|
0.07834
|
0.67834
|
0
|
|
3:55 PM
|
0.00917
|
0.125
|
0.125
|
0
|
0.01751
|
0.20334
|
0.80334
|
0
|
|
4:00 PM
|
0.01333
|
0.125
|
0.125
|
0.25
|
0.03084
|
0.32834
|
0.92834
|
0.25
|
|
4:05 PM
|
0.0225
|
0.125
|
0.125
|
0.5
|
0.05334
|
0.45334
|
1.05334
|
0.75
|
|
4:10 PM
|
0.03833
|
0.0625
|
0.125
|
0.25
|
0.09167
|
0.51584
|
1.17834
|
1
|
|
4:15 PM
|
0.05417
|
0.0625
|
0.125
|
0
|
0.14584
|
0.57834
|
1.30334
|
1
|
|
4:20 PM
|
0.0625
|
0.0625
|
0.125
|
0.2
|
0.20834
|
0.64084
|
1.42834
|
1.2
|
|
4:25 PM
|
0.06417
|
0.04167
|
0.0625
|
0
|
0.27251
|
0.68251
|
1.49084
|
1.2
|
|
4:30 PM
|
0.06583
|
0.02083
|
0.02083
|
0
|
0.33834
|
0.70334
|
1.51167
|
1.2
|
|
4:35 PM
|
0.06583
|
0.02083
|
0.02083
|
0
|
0.40417
|
0.72417
|
1.5325
|
1.2
|
|
4:40 PM
|
0.06667
|
0.02083
|
0.02083
|
0
|
0.47084
|
0.745
|
1.55333
|
1.2
|
|
4:45 PM
|
0.065
|
0.0075
|
0.01167
|
0
|
0.53584
|
0.7525
|
1.565
|
1.2
|
|
4:50 PM
|
0.06
|
0
|
0.0075
|
0
|
0.59584
|
0.7525
|
1.5725
|
1.2
|
|
4:55 PM
|
0.0575
|
0
|
0
|
0
|
0.65334
|
0.7525
|
1.5725
|
1.2
|
|
5:00 PM
|
0.05333
|
0
|
0
|
0
|
0.70667
|
0.7525
|
1.5725
|
1.2
|
|
5:05 PM
|
0.04417
|
0
|
0
|
0
|
0.75084
|
0.7525
|
1.5725
|
1.2
|
|
5:10 PM
|
0.02833
|
0
|
0
|
0
|
0.77917
|
0.7525
|
1.5725
|
1.2
|
|
5:15 PM
|
0.0125
|
0
|
0
|
0
|
0.79167
|
0.7525
|
1.5725
|
1.2
|
|
5:20 PM
|
0.00417
|
0
|
0
|
0
|
0.79584
|
0.7525
|
1.5725
|
1.2
|
|
5:25 PM
|
0.0025
|
0
|
0
|
0
|
0.79834
|
0.7525
|
1.5725
|
1.2
|
|
5:30 PM
|
0.00083
|
0
|
0
|
0
|
0.79917
|
0.7525
|
1.5725
|
1.2
|
|
5:35 PM
|
0.00083
|
0
|
0
|
0
|
0.8
|
0.7525
|
1.5725
|
1.2
|
|
5:40 PM
|
0
|
0
|
0
|
0
|
0.8
|
0.7525
|
1.5725
|
1.2
|
It looks like the N0R radar image is the best of the lot. The NCR and N1P were
not even in the ballpark.
Another comparison …
|
16-Jun-09
|
5-minute
|
5-minute
|
5-minute
|
5-minute
|
Total
|
Total
|
Total
|
Total
|
|
|
WunderG
|
NEXRAD
|
NEXRAD
|
NEXRAD
|
WunderG
|
NEXRAD
|
NEXRAD
|
NEXRAD
|
|
Date
|
KFLPARKL4
|
N0R
|
NCR
|
N1P
|
KFLPARKL4
|
N0R
|
NCR
|
N1P
|
|
4:50 PM
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
0
|
|
4:55 PM
|
0
|
0
|
0.00417
|
0
|
0
|
0
|
0.00417
|
0
|
|
5:01 PM
|
0
|
0.0075
|
0.0625
|
0
|
0
|
0.0075
|
0.06667
|
0
|
|
5:06 PM
|
0
|
0.00417
|
0.0625
|
0
|
0
|
0.01167
|
0.12917
|
0
|
|
5:10 PM
|
0
|
0.02083
|
0.5
|
0
|
0
|
0.0325
|
0.62917
|
0
|
|
5:15 PM
|
0
|
0.01167
|
0.25
|
0
|
0
|
0.04417
|
0.87917
|
0
|
|
5:21 PM
|
0
|
0.00417
|
0.25
|
0
|
0
|
0.04834
|
1.12917
|
0
|
|
5:25 PM
|
0.002
|
0.0075
|
0.25
|
0
|
0.002
|
0.05584
|
1.37917
|
0
|
|
5:30 PM
|
0.005
|
0.00417
|
0.125
|
0
|
0.007
|
0.06001
|
1.50417
|
0
|
|
5:36 PM
|
0.008
|
0.00417
|
0.0625
|
0
|
0.015
|
0.06418
|
1.56667
|
0
|
|
5:40 PM
|
0.00533
|
0.00417
|
0.02083
|
0
|
0.02033
|
0.06835
|
1.5875
|
0
|
|
5:46 PM
|
0.008
|
0
|
0
|
0
|
0.02833
|
0.06835
|
1.5875
|
0
|
|
5:50 PM
|
0.00533
|
0
|
0
|
0
|
0.03366
|
0.06835
|
1.5875
|
0
|
|
5:55 PM
|
0.0075
|
0
|
0
|
0
|
0.04116
|
0.06835
|
1.5875
|
0
|
|
6:00 PM
|
0.0075
|
0
|
0
|
0
|
0.04866
|
0.06835
|
1.5875
|
0
|
|
6:06 PM
|
0.009
|
0
|
0
|
0
|
0.05766
|
0.06835
|
1.5875
|
0
|
|
6:11 PM
|
0.0075
|
0
|
0
|
0
|
0.06516
|
0.06835
|
1.5875
|
0
|
|
6:16 PM
|
0.0075
|
0
|
0
|
0
|
0.07266
|
0.06835
|
1.5875
|
0
|
|
6:20 PM
|
0.006
|
0
|
0
|
0
|
0.07866
|
0.06835
|
1.5875
|
0
|
|
6:25 PM
|
0.005
|
0
|
0
|
0
|
0.08366
|
0.06835
|
1.5875
|
0
|
|
6:30 PM
|
0.0025
|
0
|
0
|
0
|
0.08616
|
0.06835
|
1.5875
|
0
|
|
6:36 PM
|
0.001
|
0
|
0
|
0
|
0.08716
|
0.06835
|
1.5875
|
0
|
|
6:40 PM
|
0.00067
|
0
|
0
|
0
|
0.08783
|
0.06835
|
1.5875
|
0
|
|
6:45 PM
|
0.00083
|
0
|
0
|
0
|
0.08866
|
0.06835
|
1.5875
|
0
|
|
6:50 PM
|
0.00083
|
0
|
0
|
0
|
0.08949
|
0.06835
|
1.5875
|
0
|
|
6:55 PM
|
0
|
0
|
0
|
0
|
0.08949
|
0.06835
|
1.5875
|
0
|
It looks like N0R is the only viable Radar Image for point rainfall
determinations. That is good because
N1P is a pain in the… you know what.
NCR is just laughable. They may both
have value for larger areas and larger storms, but why bother. (update...
obviously I was a radar rube, turns out NOAA knows what they are doing. Just use the N0R
and dont embarrass yourself like me.)
The time lag between N0R rainfall and Wunderground seems to be due to something
peculiar to Wunderground. The radar
clearly showed this small storm had moved out of the area yet Wunderground was
still reporting rainfall 30 minutes later.
I would like to pick a Wunderground gage in my area for visual
confirmation, but it never rains in the desert!
Ok, it’s on my list.
Daily Comparisons for past 7 days
Here are daily rainfalls for the past week. I think N1P and NCR are shown not to be worth further comparisons.
What say you?!!
The final blow or the coupe de gras (i hope that's french or latin) is revealed
on June 16. NCR says 1.6" and N1P says zero. What goes on at Nexrad
headquarters anyway?!! ;-)
The Wunderground rain gage storm duration is again very long so I have moved to
another new Wunderground gage a few miles away in Boca Raton, FL. This gage
showed a strong peak and a duration about the same as what the radar showed.
And I am not trying to cherry pick my intended results (too much). I
just doubt thunderstorms this time of year look like drizzle. Do these
Wundergrounders ever check for bird nests in their tipping buckets??? I
quess science isn't always as cheap as one hopes. ;-)
KFLBOCAR4
The boundary file is:
KFLBOCAR4 Area1 X,Y Coordinates (pix)
324, 182
324, 184
326, 184
326, 182
324, 182
Xmin 324, Ymin 182, Xmax 326, Ymax 184 Area1= 2.20 (pix^2), Perimeter= 7.17
(pix), Centroid= 325, 183
The point file is:
325,183,325,183
1
Temporarily had to move to
Melborne MLB radar as AMX was down.
|
23-Jun-09
|
5-minute
|
5-minute
|
|
Total
|
Total
|
|
PDT
|
WunderG
|
NEXRAD
|
|
WunderG
|
NEXRAD
|
|
Date
|
KFLBOCAR4
|
N0R
|
|
KFLBOCAR4
|
N0R
|
|
12:30
|
0
|
0
|
|
0
|
0
|
|
12:35
|
0
|
0.0625
|
|
0
|
0.0625
|
|
12:40
|
0.62333
|
0.125
|
|
0.62333
|
0.1875
|
|
12:45
|
0.52167
|
0.0625
|
|
1.145
|
0.25
|
|
12:50
|
0.215
|
0.04167
|
|
1.36
|
0.29167
|
|
12:55
|
0.07917
|
0.04167
|
|
1.43917
|
0.33334
|
|
13:00
|
0.096
|
0.0625
|
|
1.53517
|
0.39584
|
|
13:05
|
0.01067
|
0.0625
|
|
1.54584
|
0.45834
|
|
13:10
|
0.011
|
0.0075
|
|
1.55684
|
0.46584
|
|
13:15
|
0.004
|
0.01167
|
|
1.56084
|
0.47751
|
|
13:20
|
0.00417
|
0.0075
|
|
1.56501
|
0.48501
|
|
13:25
|
0.00417
|
0.01167
|
|
1.56918
|
0.49668
|
|
13:30
|
0.00417
|
0.01167
|
|
1.57335
|
0.50835
|
|
13:35
|
0.00417
|
0.02083
|
|
1.57752
|
0.52918
|
|
13:40
|
0.00583
|
0.02083
|
|
1.58335
|
0.55001
|
|
13:45
|
0.00583
|
0.02083
|
|
1.58918
|
0.57084
|
|
13:50
|
0.00417
|
0.02083
|
|
1.59335
|
0.59167
|
|
13:55
|
0.004
|
0.01167
|
|
1.59735
|
0.60334
|
|
14:00
|
0.00333
|
0.01167
|
|
1.60068
|
0.61501
|
|
14:05
|
0.00267
|
0.02083
|
|
1.60335
|
0.63584
|
|
14:10
|
0.00333
|
0.02083
|
|
1.60668
|
0.65667
|
|
14:15
|
0.00333
|
0.02083
|
|
1.61001
|
0.6775
|
|
14:20
|
0.004
|
0.01167
|
|
1.61401
|
0.68917
|
|
14:25
|
0
|
0
|
|
1.61401
|
0.68917
|
|
14:30
|
0
|
0
|
|
1.61401
|
0.68917
|
Well this comparison does not
look good!
I have reevaluated my dbz to rainfall rates and updated Getrealtime.exe to
use the log interpolation values from the following table. This will tend
to lower the low rates and greatly raise the higher rates.
NWS Nexrad N0R & NCR dbz versus rainfall rate in inches (Z = 200R^1.6
mm/hr)
Dbz
in/hr
|
65
|
16+
|
|
60
|
8
|
|
55
|
4
|
|
52
|
2.5
|
|
47
|
1.25
|
|
41
|
0.5
|
|
36
|
0.25
|
|
30
|
0.1
|
|
20
|
Trace
|
Another NWS table had the following values which I have adopted on 6/29/09. The NWS table only covered the values
through 55 dbz and listed the remaining as greater than 5.67. Here is the table I am now using:
Table 6/29/07 (above 60 dbz revised 12/17/09):
|
Reflectivity (dBz)
|
Rainfall Rate (inches/hr
)
|
|
20
|
0.02
|
|
25
|
0.04
|
|
30
|
0.09
|
|
35
|
0.21
|
|
40
|
0.48
|
|
45
|
1.10
|
|
50
|
2.49
|
|
55
|
5.67
|
|
60
|
6
|
|
65
|
6.5
|
|
70
|
7
|
|
75+
|
8
|
This table seems to have been constructed from a mid range Z-R relation of the
form Z=a+b*log(R) where a=27.14 and b=14.108 (a=46.96 for in/hr) and not a slightly different
classical step Z=aR^b form which by the way is only a statistical, not a
physical thing. It seems to work really well so if anyone can tell me more about
this Z-R please comment or email me. And isn't there some statistical rule
against just reversing the dependent and independant variables in a regression formula to
get rain rates. I guess that is the least of the problems here.
Update 8/17/10: It turns out the rates above are actually not mid range
such as 22.5 but actually the standard convective WSR-88D rates at the stated
dbz. So color green 20 dbz >>> 200R^1.4 gives the right value stated of 0.02
in/hr. Well that is a load off! But what is with the 5 dbz color bins and
not the 0.5 dbz resolution of the radar??? This is not 1988 with just 16
colors anymore.
The formulas below are from the NOAA ROC for other conversions you may wish to
try:
Marshall-Palmer (Z=200R^1.6) General stratiform precipitation
East-Cool Stratiform (Z=130R^2.0) Winter precipitation - east of
continental divide
West-Cool Stratiform (Z=75R^2.0) Winter precipitation - west ofcontinental
divide
WSR-88D Convective (Z=300R^1.4) Summer deep convection
Rosenfeld Tropical (Z=250R^1.2) Tropical convective
My Semi-Tropical (no z-r) Average of Tropical and Convective
|
Reflectivity (dBz) |
Rainfall Rate inches/hr |
Marshall Palmer |
East Cool |
West Cool |
WRD-88D convective |
My Semi-
Tropical |
Tropical |
|
10 |
-- |
0 |
0.01 |
0.01 |
0 |
0 |
0 |
|
15 |
-- |
0 |
0.02 |
0.03 |
0 |
0 |
0 |
|
20 |
0.02 |
0.03 |
0.03 |
0.05 |
0.02 |
0.02 |
0.02 |
|
25 |
0.04 |
0.05 |
0.06 |
0.08 |
0.04 |
0.04 |
0.05 |
|
30 |
0.09 |
0.11 |
0.11 |
0.14 |
0.09 |
0.11 |
0.12 |
|
35 |
0.21 |
0.22 |
0.19 |
0.26 |
0.21 |
0.27 |
0.33 |
|
40 |
0.48 |
0.45 |
0.35 |
0.45 |
0.48 |
0.67 |
0.85 |
|
45 |
1.1 |
0.93 |
0.61 |
0.81 |
1.10 |
1.66 |
2.22 |
|
50 |
2.49 |
1.91 |
1.09 |
1.44 |
2.50 |
4.15 |
5.80 |
|
55 |
5.67 |
3.93 |
1.94 |
2.56 |
5.20 |
6.86 |
8.52 |
|
60 |
6 |
5.20 |
3.45 |
4.55 |
5.20 |
7.0 |
8.52 |
|
65 |
6.5 |
5.20 |
5.20 |
5.20 |
5.20 |
7.5 |
8.52 |
|
70 |
7 |
5.20 |
5.20 |
5.20 |
5.20 |
8.0 |
8.52 |
|
75 |
8 |
5.20 |
5.20 |
5.20 |
5.20 |
8.5 |
8.52 |
You may want to limit the maximum rainfall rates for your point of interest.
Proper use of adaptable
parameters. "As mentioned earlier, several adaptable parameters have a
bearing on the precipitation algorithm. Two such adaptable parameters are the
Z/R relationship and the maximum precipitation rate (MXPRA). The default Z/R
relationship in the WSR-88D is the Convective Z=300R1.4, and the default MXPRA
was established at 53 dBZ which equates to a maximum rainfall rate of 103.8
mm/hr (4.09 in/hr). This value was established to eliminate the effects of hail
contamination on rainfall estimates, but on occasion, rainfall rates of greater
than 103.8 mm/hr were observed."
Comparison 6/24/09: Miami AMX radar back up and was used
for this comparison. It looks like
the new dbz to rainfall rate may be helping.
|
24-Jun-09
|
5-minute
|
5-minute
|
|
Total
|
Total
|
|
PDT
|
WunderG
|
NEXRAD
|
|
WunderG
|
NEXRAD
|
|
Date
|
KFLBOCAR4
|
N0R
|
|
KFLBOCAR4
|
N0R
|
|
13:00
|
0
|
0
|
0
|
0
|
0
|
|
13:05
|
0
|
0.00167
|
0
|
0
|
0.00167
|
|
13:10
|
0
|
0.00167
|
0
|
0
|
0.00334
|
|
13:15
|
0
|
0.0125
|
0
|
0
|
0.01584
|
|
13:20
|
0.0075
|
0.0525
|
0.0075
|
0.0075
|
0.06834
|
|
13:25
|
0.04
|
0.02583
|
0.04
|
0.0475
|
0.09417
|
|
13:30
|
0.02583
|
0.0125
|
0.02583
|
0.07333
|
0.10667
|
|
13:35
|
0.01583
|
0.005
|
0.01583
|
0.08916
|
0.11167
|
|
13:40
|
0.009
|
0.00167
|
0.009
|
0.09816
|
0.11334
|
|
13:45
|
0.00417
|
0
|
0.00417
|
0.10233
|
0.11334
|
|
13:50
|
0.00333
|
0
|
0.00333
|
0.10566
|
0.11334
|
|
13:55
|
0
|
0
|
0
|
0.10566
|
0.11334
|
|
14:00
|
0
|
0
|
0
|
0.10566
|
0.11334
|
Comparison 6/26/09:
|
26-Jun-09
|
5-minute
|
5-minute
|
|
Total
|
Total
|
|
PDT
|
WunderG
|
NEXRAD
|
|
WunderG
|
NEXRAD
|
|
Date
|
KFLBOCAR4
|
N0R
|
|
KFLBOCAR4
|
N0R
|
|
9:00
|
0
|
0
|
|
0.000
|
0.000
|
|
9:05
|
0
|
0.00083
|
|
0.000
|
0.001
|
|
9:10
|
0
|
0.00417
|
|
0.000
|
0.005
|
|
9:15
|
0
|
0.00083
|
|
0.000
|
0.006
|
|
9:20
|
0
|
0.00083
|
|
0.000
|
0.007
|
|
9:25
|
0
|
0.00083
|
|
0.000
|
0.007
|
|
9:30
|
0
|
0.00417
|
|
0.000
|
0.012
|
|
9:35
|
0.02
|
0.02583
|
|
0.020
|
0.037
|
|
9:40
|
0.00833
|
0.0125
|
|
0.028
|
0.050
|
|
9:45
|
0.08833
|
0.02583
|
|
0.117
|
0.076
|
|
9:50
|
0.18917
|
0.0525
|
|
0.306
|
0.128
|
|
9:55
|
0.0275
|
0.0525
|
|
0.333
|
0.181
|
|
10:00
|
0.0275
|
0.0125
|
|
0.361
|
0.193
|
|
10:05
|
0.010835
|
0.0125
|
|
0.372
|
0.206
|
|
10:10
|
0.010835
|
0.0125
|
|
0.383
|
0.218
|
|
10:15
|
0.00667
|
0.0125
|
|
0.389
|
0.231
|
|
10:20
|
0.00667
|
0.00417
|
|
0.396
|
0.235
|
|
10:25
|
0.00533
|
0.00417
|
|
0.401
|
0.239
|
|
10:30
|
0.007
|
0.0125
|
|
0.408
|
0.252
|
|
10:35
|
0.00333
|
0.00417
|
|
0.412
|
0.256
|
|
10:40
|
0
|
0.00417
|
|
0.412
|
0.260
|
|
10:45
|
0
|
0.0125
|
|
0.412
|
0.273
|
|
10:50
|
0
|
0.0125
|
|
0.412
|
0.285
|
|
10:55
|
0.019165
|
0.02583
|
|
0.431
|
0.311
|
|
11:00
|
0.019165
|
0.02583
|
|
0.450
|
0.337
|
|
11:05
|
0.015
|
0.02583
|
|
0.465
|
0.362
|
|
11:10
|
0.01417
|
0.02583
|
|
0.479
|
0.388
|
|
11:15
|
0.01167
|
0.02583
|
|
0.491
|
0.414
|
|
11:20
|
0.00833
|
0.02583
|
|
0.499
|
0.440
|
|
11:25
|
0.01417
|
0.02583
|
|
0.513
|
0.466
|
|
11:30
|
0.00917
|
0.0125
|
|
0.522
|
0.478
|
|
11:35
|
0.0075
|
0.0125
|
|
0.530
|
|