CLENSEMBLE 3.1 :

\*\* Modified to add 12 hour snowfall probabilities of 1,4,8,12 inches

Introduction: CLENSEMBLE is a software package that produces a model
ensemble from locally produced WRF models. There are two parts to the
software; the first part dissects a subset of fields from the original
grib file. These files can then be easily shared with surrounding sites.
The second part of the software produces an ensemble in grib2 format
from up to ten different subsets. These grids can then be ingested into
both GFE and D2D.

The need for the subset comes from the fact the WRF produces over 750
forecast fields. These grib files were considered too large to transport
due to current bandwidth issues. However, the vast majority of the
fields are not directly useful for operational weather forecasting.
Also, many useful fields can be recalculated later in AWIPS, GRADS or
GEMPAK. For example, vorticity can be derived from the wind fields.
WRFdissect software extracts a subset of 53 fields from the final grib
file produced by the WRF. The final output is significantly smaller than
the original grib file, averaging around 100 K. These files can then be
shared with other WFO offices with minimal detrimental effects on the
local computer network.

Part two of the software is called MAKENSEMBLE. It produces an ensemble
mean of up to ten separate model inputs. The output data format is
grib2. This format can be imported in AWIPS. The user has the choice to
either weigh each model equally for a simple model average, or to
customize each model's weight using a single configuration file. The
lists of variables produced are in table one.

In addition to the mean grib2 fields, probability fields are produced.
These include most fields produced in the SREF, including QPF, wind,
member spreads, Lifted Index and CAPE, table 2d. Unlike the mean grib2
fields, the probability images cannot be customized. Each model member
is weighted equally. For example, if four models out of five are
predicting gale force winds, the graph shows an 80 percent chance of
getting gale force winds. All fields are produced in grib2 format.
Listed fields in table 2b, 2c and 2d are available in D2D.

Table 1 mean fields available in d2d (grib2 files)

• Indicates derived fields in AWIPS

  -------------------- --------- ---- ----- ------ ----- ----- ----- ----- -----
                       Surface   2 m  10 m  1000   900   850   700   500   300

  Temp                                                               

  Dew P                                                              

  Wind                                                               

  HGT                                                                 

  Omega                                                                

  MSLP                                                                    

  Cape                                                                    

  Radar Reflect                                                           

  Precipitable Water                                                      

  1 Hour QPF                                                              

  Vorticity \*                                                        

  Divergence \*                                                       

  Temp advection\*                                                    

  Potential Temp\*                                                    

  Potential Temp                                                      
  Advection \*                                                             

  Dew Pt Depression \*                                                

  Q vectors \*                                                         

  Fs vectors \*                                                        

  Geotropic wind \*                                                    

  Ageotropic Wind \*                                                   

  Deformation \*                                                       

  Preferred Ice Growth                                                 
  \*                                                                       

  Relative Humidity \*                                               
  -------------------- --------- ---- ----- ------ ----- ----- ----- ----- -----

Table 2a Probability GIF images created for D2D (grib2)

  -------------------------------------- ----- ----- ----- ----- ----- -----
                                         06    12    18    24    30    36

  Small Craft winds 21 kt                                         

  Gale Warning winds 34 kt                                        

  Storm Warning winds 48 kt                                       
  -------------------------------------- ----- ----- ----- ----- ----- -----

Table 2b QPF Probability Fields available in D2D

+--------------+----------------+------------------+------------------+
|              | 6 hour period  | 12 hour Period   | 24 hour Period   |
+--------------+----------------+------------------+------------------+
| .01 inch     | 6,12,18,24,36  | 12,18,24,36      | 24,36            |
|              |                |                  |                  |
|              | Hr Forecast    | Forecast         | Forecast         |
+--------------+----------------+------------------+------------------+
| .05 inch     | 6,12,18,24,36  | 12,18,24,36      | 24,36            |
|              |                |                  |                  |
|              | Hr Forecast    | Forecast         | Forecast         |
+--------------+----------------+------------------+------------------+
| .10 inch     | 6,12,18,24,36  | 12,18,24,36      | 24,36            |
|              |                |                  |                  |
|              | Hr forecast    | Forecast         | Forecast         |
+--------------+----------------+------------------+------------------+
| .25 inch     | 6,12,18,24,36  | 12,18,24,36      | 24,36            |
|              |                |                  |                  |
|              | Hr Forecast    | Forecast         | Forecast         |
+--------------+----------------+------------------+------------------+
| .50 inch     | 6,12,18,24,36  | 12,18,24,36      | 24,36            |
|              |                |                  |                  |
|              | Hr Forecast    | Forecast         | Forecast         |
+--------------+----------------+------------------+------------------+
| 1.  Inch     | 6,12,18,24,36  | 12,18,24,36      | 24,36            |
|              |                |                  |                  |
| 2.  Inch     | Hr Forecast    | Forecast         | Forecast         |
+--------------+----------------+------------------+------------------+

Table 2c New Probabilities with version3.1

<table>
<colgroup>
<col style="width: 8%" />
<col style="width: 9%" />
<col style="width: 5%" />
<col style="width: 8%" />
<col style="width: 8%" />
<col style="width: 4%" />
<col style="width: 12%" />
<col style="width: 6%" />
<col style="width: 7%" />
<col style="width: 7%" />
<col style="width: 6%" />
<col style="width: 13%" />
</colgroup>
<tbody>
<tr class="odd">
<td colspan="2">Hourly</td>
<td colspan="2">Hourly</td>
<td colspan="2">Hourly</td>
<td>Hourly</td>
<td colspan="2">Hourly</td>
<td colspan="2">Hourly</td>
<td>Hourly</td>
</tr>
<tr class="even">
<td colspan="2">LI &lt; 0</td>
<td colspan="2">LI &lt; -4</td>
<td colspan="2">LI &lt; -8</td>
<td>Cape &gt; 500 J</td>
<td colspan="2">Cape &gt; 1000 J</td>
<td colspan="2">Cape &gt; 2000 J</td>
<td>Cape &gt; 4000 J</td>
</tr>
<tr class="odd">
<td colspan="2">Hourly</td>
<td colspan="2">Hourly</td>
<td colspan="2">Hourly</td>
<td></td>
<td colspan="2"></td>
<td colspan="2"></td>
<td></td>
</tr>
<tr class="even">
<td colspan="2">850 MB Spread Temp</td>
<td colspan="2"><p>500 MB</p>
<p>Spread</p>
<p>Temp</p></td>
<td colspan="2"><p>500 MB</p>
<p>Spread</p>
<p>GH</p></td>
<td></td>
<td colspan="2"></td>
<td colspan="2"></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td colspan="2">Time period</td>
<td colspan="2">6 hour period</td>
<td colspan="3">12 hour Period</td>
<td colspan="2">24 hour Period</td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td></td>
<td colspan="2">Member spreads</td>
<td colspan="2"><p>6,12,18,24,36</p>
<p>Hr QPF spreads</p></td>
<td colspan="3"><p>12,18,24,36</p>
<p>Hr QPF spreads</p></td>
<td colspan="2"><p>24,36</p>
<p>Hr QPF spreads</p></td>
<td colspan="2"></td>
</tr>
</tbody>
</table>

Snow Probabilities

+-------------+-------------+-------------+-------------+-------------+
|             | 12          | 18          | 24          | 36          |
+-------------+-------------+-------------+-------------+-------------+
| Probability | X           | X           | X           | X           |
| Snow        |             |             |             |             |
|             |             |             |             |             |
| \> 1 inch   |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Probability | X           | X           | X           | X           |
| Snow        |             |             |             |             |
|             |             |             |             |             |
| \> 4 inch   |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Probability | X           | X           | X           | X           |
| Snow        |             |             |             |             |
|             |             |             |             |             |
| \> 8 inch   |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+
| Probability | X           | X           | X           | X           |
| Snow        |             |             |             |             |
|             |             |             |             |             |
| \> 12 inch  |             |             |             |             |
+-------------+-------------+-------------+-------------+-------------+

The Eastern Great Lakes Ensemble

![](media/image1.png){width="5.988888888888889in"
height="4.895138888888889in"}

Figure 1 Example from Great Lakes Ensemble domain

Figure 1 is an example of an ensemble domain. This domain has a 12 km
resolution across a large area across the eastern great lakes. Each
member of the ensemble will be resized to the above dimensions using a
Haines analysis. Successful testing has included adding members with
resolutions ranging from 6 km to 80 km. However, the domain of any
ensemble is limited to the smallest intersecting area of all the
ensemble members. This means the smallest member will be the largest
possible ensemble domain, but not necessarily the final ensemble domain.

## 

## 

Table 3 Ensemble model members (Note NEW members are being may be added
in 12/08)

![](media/image1.wmf)

Table 3 shows each of the members boundary conditions, microphysics and
model core. Each model is weighted equally. However, each model can be
given a unique weight as long as the total is 100 percent. Each model
has unique physics, model core and initial boundary sources.

The below image is a probabilistic field. It shows the chance of getting
winds that will require a small craft warning. At this time only GIF
images will be produced. Figure 2 shows the probability of getting small
craft winds.

![](media/image2.png){width="5.9944444444444445in"
height="4.795138888888889in"}

Figure 2 Probability of exceeding wind threshold that requires a small
craft warning

Figure 2 is an example of a probability image. This image shows the
probability getting winds strong enough that requires a small craft
warning. Each model is weighted equally. Eighty percent of the model
ensemble members are forecasting winds that will exceed 21 knots,
requiring a small craft warning.

![](media/image3.png){width="5.9944444444444445in"
height="4.795138888888889in"}

Figure 3 Probability of run total QPF \> .05 inches

Figure 3 is an example of a probability image. This image shows the
probability getting .05 inches of precipitation. It is an 18-hour run
QPF total beginning at 0600Z. Figure 4 is an example of an ensemble
10-meter field in GFE.

![](media/image4.png){width="5.992361111111111in"
height="4.6506944444444445in"}

Figure 4 An Ensemble 10 meter wind field in GFE

Figure 5 and Figure 6 are probability images in D2D. The user must
display the volume browser. Select the model, SUPERENS being the
default, and select the fields from the Ensemble/SREF precipitation
menu. See example. Each fields is the probability of reaching a certain
precipitation threshold in a 6,12 or 24 hour period.

Figure 5 The Volume Browser in D2D

Figure 6 is an example of a probability field. The values range from 0
to 100 percent. This image is the chance of getting over .01 inches of
precipitation in a 12-hour period.

![](media/image5.png){width="5.988194444444445in"
height="5.029166666666667in"}

Figure 6 Probability image in D2D

Below are probability fields added with version 3 from D2D. These
figures can be displayed by choosing the SUPERENS (or whatever it is
named) as the model of choice in the volume Browser and using the SREF
ensemble menu. Figure 7 is an example of the temperature spread of the
members. This is calculated by subtracting the greatest value at each
point minus the smallest value from the corresponding point. Figure 7
through Figure 10 are CAPE, LI and wind probabilities of reaching a
certain threshold.

![](media/image6.png){width="6.0in" height="4.8in"}

Figure 7 Examples of 850 mb Temperature Spreads

![](media/image7.png){width="6.0in" height="4.8in"}

Figure 8 Example of CAPE probabilities

![](media/image8.png){width="6.0in" height="4.8in"}

Figure 9 Example of LI probabilities

![](media/image9.png){width="6.0in" height="4.8in"}

Figure 10 Example of wind probabilities