Using GOES-R IFR/LIFR Probabilities for TAFs

Tracking areas of stratus and fog can be somewhat difficult using traditional satellite images along with METAR observations...particularly on a day with a variety of low and high level clouds. Sky conditions across the Great Lakes during the afternoon of November 6th is a good example. Below are infrared and visible GOES images along with plotted METAR ceilings and visibilities:

GOES Infrared

GOES Visible

Note how conditions are evident at point locations, but it is difficult to discriminate areal coverage across the region. For the purpose of issuing and updating TAFs, it would be very useful to better visually display areas of lower ceilings and visibilities, increasing situational  awareness and improving the ability to track and forecast improving or deteriorating conditions. Fortunately, GOES-R fog and low clouds products are proving quite useful in filling this need. Below are images of GOES-R IFR probabilitly and LIFR probability:

GOES-R IFR Probability

GOES-R LIFR Probability

The IFR product does a very good job of showing the area of ceilings that are less than 1000 feet, particularly for values above 60 percent. Though LIFR percentages are not very high, the highest percentages do coincide pretty well with some of the lower ceilings and visibilities in the region. Something that was immediately useful was observing a loop of the IFR image, which showed that the eastern edge of the lower ceilings had temporarily stalled across eastern Wisconsin. This might lead to delaying the arrival of IFR ceilings in eastern TAF sites.

Another likely use of the GOES-R fog and low cloud products would be tracking stratus or fog advecting into Wisconsin off of Lake Michigan. Using an example off the California coast, note that GOES infrared and fog images will give you an idea of where there is cloud cover, but will not give and immediate idea of what type of conditions are moving into the area:

GOES Infrared

GOES IR Fog

While the traditional fog product above does give a clue that you're looking at either fog or stratus...the GOES-R IFR and LIFR products confirm this and also give an indication of how low the ceilings and/or visibilites are:

GOES-R IFR Probability

GOES-R LIFR Probability

It is immediately clear the conditions are at or below IFR for much of the area of fog/stratus...with a pretty good probability of LIFR conditions over a large portion of the area. This is quite useful...as ceiling and visibility observations are very limited over bodies of water. Hopefully the use of this product will help in troublesome situations where poor conditions can sneak onshore... particularly when somewhat obstructed by other cloud decks.

In summary, GOES-R fog and low cloud products can be very useful in tracking areas of fog and stratus. In contrast to using a combination of surface observations and traditional visible/infrared products, the GOES-R products can give a very quick and fairly accurate representation of where IFR or worse conditions are located. Being able to track these areas will hopefully lead to improvements in TAFs.

Denny VanCleve
NWS Milwaukee/Sullivan

GOES-R AWG Fog/Low Cloud Products

Conditions across the middle of the U.S. were ideal for assessing this product. Strong low pressure was forming over the High Plains while high pressure was situated along the Atlantic Coast of the southeast U.S.  Warm air and copious moisture were flowing north up the Mississippi Valley. This morning we focused on the southern coast of Louisiana.  The Louisiana case looked almost completely radiation induced.

When I was introduced to this product during the GOES-R proving ground activities of 2011, I was, to be honest, rather underwhelmed.  Back then, this product used satellite interrogation coupled with boundary layer RH from the GFS.  No observations were included in the assessment and therefore it didn't seem to perform any better than my simply using available satellite imagery and surface obs (and experience.) This year, it appears there has been significant improvement to the inputs of this product.  The boundary layer RH now comes from the Rapid Refresh Model.  Not only is the RH data resolution improved both spatially and temporally, but the Rapid Refresh incorporates the latest surface observations into its output fields.  From the few examples I saw, it is apparent this product will sometimes highlight an area, showing increased probabilities of IFR/LIFR, before these conditions appear in the observations.  This appears to be the strength of using the high resolution Rapid Refresh output.

Anyway, here is the example down along the southern coast of Louisana:

The forecaster working on the 06z TAFs would have used the GFS and NAM MOS (MET/MAV) as part of the decision aid on ceiling and visibility.  In this example, we'll look at the observation in far southeast TX, MTRJAS. See location in image below:

 Here are the METJAS and the MAVJAS products respectively at 00z Oct 23rd, 2012:

 _________________________________________________________________________________

Note the ceiling prediction shows VFR conditions dropping to MVFR from 06z-12z Oct 23rd.  No real hint of IFR, though the temp/dewpoint spread does get pretty tight in the morning.

Below are a series of 4-panel images running from 04:02Z-09:15Z Oct 23, 2012 showing a combination of GOES-R and heritage products.  See caption on first image for details. Note the GOES-R IFR probability is beginning to highlight far southeast TX with increasing probabilities of IFR at 04:02Z. MTRJAS at this point is indicating clear skies and 10 mile visibility.


GOES-R IFR Probability upper left, LIFR probability upper right, heritage brightness temperature difference product lower left, visibible image lower right

 The following image is an hour later at 05:02Z:  MTRJAS is still clear and 10 miles, but note the increasing probabilities of IFR.

At 06:15Z:  MTRJAS is now indicating Clear and 5 miles in fog...probabilities continue to show a trend toward IFR

At 07:15Z:  MTRJAS is Clear and 7 miles visibility.

At 08:15z:  MTRJAS has now gone down to a 200ft broken ceiling and 7 miles visibility. 

And finally at 09:15Z: MTRJAS dropped to as low as 200ft overcast and 2 miles, before seeing improving conditions after about 09:30Z.

In summary, it is clear that, in this case, the GOES-R IFR probability products can give the forecaster an early heads-up that conditions are on their way down to IFR conditions, despite the traditional MOS products from the GFS and the NAM indicating no IFR conditions for that METAR site. 

Steve Davis
CIMSS-MKX

Cloud Top Cooling Skillful before Severe Storms

Today's severe thunderstorm warnings were preceded by cloud top cooling rates of around 30 degrees Celsuius per 15 minutes -- around 30 minutes before warnings were actually issued!

Here is the time series of cells that developed over Winona County, Minnesota.  They produced golf-ball size hail.  The panels, from upper left to upper right and lower left to lower right, are:  cloud top cooling with visible satellite image background, convective initiation categorical classification with visible satellite image background, IR window satellite image, and radar base reflecitivity.

2002 UTC 4 September 2012

2015 UTC 4 September 2012

2032 UTC 4 September 2012

Here is the time series of cells that developed over Barron County, Wisconsin.  There were several reports of large hail over an inch in diameter.

2015 UTC 4 September 2012

2032 UTC 4 September 2012

2045 UTC 4 September 2012



It was exciting to see the performance of this algorithm in real-time.

J.J. Wood, General Forecaster, Milwaukee/Sullivan WFO

Jordan Gerth, Meteorologist, CIMSS/SSEC Madison, WI

Aug 9, 2012 CTC & Radar Comparison

Given active weather pattern (deepening upper level trough over Great Lakes) with showers and storms over Wisconsin, it wasn't hard to find quick growing cells with at least moderate Cloud Top Cooling (CTC) rates.

There were some breaks in the cloud field over northwestern Wisconsin.  Perhaps this helped oen cell in a line to pulse up.  We were able to spot CTC rates in the moderate range with a value of 17 to 18 over northwestern Washburn County.  Further north in St. Louis County of northeastern Minnesota we observed a CTC value of 12 to 13. See Figure 1 below.

Figure 1. Maximum CTC rates of 17 to 18 over Washburn County.

 We then compared the cells with decent CTC rates with what the WSR-88D Radars depicted.  SEe Figure 2 below for the radar image which corresponds to Figure 1.

Figure 2. Radar image at 1643Z August 9, 2012.

The decent CTC rates would imply an increase in cell intensity observed on radar.  This intensity increase is noted in Figure 3 below, especially in the St. Louis cell which had a 60 dBZ signature.  Of course, these storms were not severe, but it was nice to see that the CTC rate idea enabled us to anticipate an increase in cell intensity.

Figure 3. Radar image at 1706z August 9, 2012.

Rusty Kapela - MKX
Ed Townsend - MKX
Justin Sieglaff - CIMSS

August 9, 2012 GOES-R FLS

This was my first exposure (shift) with GOES-R material (luck of the draw?).  Appreciated the lesson and learned a lot. I was impressed with the probability FLS image and comparing it to the older satellite images of low clouds/stratus.  I can see the utility with generating the TAFS...the FLS product will give me more confidence to go or not go with fog/stratus IFR conds.  The limitations at twilight were explained....makes sense.  Always great to have more tools at our disposal!

Some examples of the FLS probability product are shown in central Indiana. In Fig. 1, you can see a known characteristic with the cloud depth product, wherein the cloud phase product shows ice-based clouds "blacked out".  This is a result of the cloud depth product being limited to water-based clouds.  Also, note in Fig. 1 a swath of greater than 50% prob is located in east central IN. The nearest stations are showing CIGs of 110 and 95 hft and are outside this yellow swath.

Fig. 1. 1302Z: Cloud depth, IFR FLS Product, VIS Sat, GOES Cloud type(from top-left going clockwise).

In Fig. 2, the FLS product is now showing high probability of fog or low-level stratus.  However, the obs in the center of this high probability swath is reporting clear skies at 10 SM visibility.  Vis satellite was inspected and it reveals broken-overcast skies in this swath of high probabilities.  This was an interested feature given the initial discrepancies between the observations and the FLS product.  However, it was noted that the report of the obs was 1353 Z.  Wherein the satellite products have a time stamp of 1332. Thus, this is more so an artifact of this case (postmortem), where the observations and satellite products are not synchronized.  In a real-time situation, this is not anticipated to be an issue.

Fig. 2. 1332Z: Cloud depth, IFR FLS Product, VIS Sat, GOES Cloud type(from top-left going clockwise).

 In Fig. 3, the FLS product time stamp is 1402, which is now better aligned with this aforementioned METAR report at 13:53.

Fig. 3. 1402Z: Cloud depth, IFR FLS Product, VIS Sat, GOES Cloud type(from top-left going clockwise).

Further to the west, over the MKX WFO the GOES-R FLS IFR product performed well depicting the gradient in ceilings.  With low probabilities along a Madison to Milwaukee line; but increasing probabilities towards Wisconsin Dells  to West Bend.  Fig. 4 illustrates that the higher IFR probabilities to the north indeed matchup with lower ceilings, around 500 feet.  The ceilings over Milwaukee and Madison were 2700-4300 feet.

Fig. 4 1332 UTC Cloud depth, IFR FLS Product, GOES VIS, Heritage Fog GOES BTD(from top-left going clockwise).

To the northwest, the GOES-R FLS IFR probabilities captured a small, yet operationally significant area of low ceilings near and east of Fargo, ND  (Fig. 5).  The surface observations agree with the higher probabilities with 500-900 foot ceilings.

Fig. 5 1132 UTC Cloud depth, IFR FLS Product, GOES VIS, Heritage Fog GOES BTD (from top-left going clockwise).

It should be noted AWIPS @ MKX has been rolled back to an older version in preparation for upgrades to AWIPS-II.  As such, the products and enhancements are not current.

Ed Townsend - MKX
Rusty Kapela - MKX
Justin Sieglaff - CIMSS

Moonlit Overshooting Tops in NPP VIIRS Day/Night Band

A strong cluster of thunderstorms developed over Central Michigan overnight on 3 July 2012.  These thunderstorms were captured by the Suomi NPP satellite overpass at 07:42 UTC by the Direct Broadcast antenna located at the University of Wisconsin-Madison Cooperative Institute for Meteorological Satellite Studies (CIMSS).  The data was processed and sent in real-time to the NWS office at Sullivan (MKX) where it was displayed in AWIPS.  The VIIRS Day/Night band provides forecasters with visible imagery at night at high spatial resolution (1km) from lunar illumination.  The first image below shows the features of the cloud tops, including overshooting tops as well as gravity waves.  Also visible are the lights emanating from the underlying cities including Detroit (large bright lights in the Southeast Corner).  The infrared 11 micron window brightness temperature image (second image) provides a thermal view of the same scene.  The coldest tops are -70C.      

Suomi NPP VIIRS Day/Night Band image of a strong thunderstorm over Central Michigan illuminated by moonlight with overshooting tops and gravity waves evident.  The Day/Night band supplies forecasters with a visible band capability at night when the moon is out.  The VIIRS data is acquired from the direct broadcast antenna at the University of Wisconsin-Madison CIMSS, processed via CSPP software and supplied to the NWS MKE office in real-time for display in AWIPS.  The image is from 3 July 2012, 07:42 UTC.

Suomi NPP VIIRS Window Channel Infrared image (11 micron) of a strong thunderstorm over Central Michigan.  The coldest cloud tops are -70 C, and the spatial resolution is about 1 km.  The VIIRS data is acquired from the direct broadcast antenna at the University of Wisconsin-Madison CIMSS, processed via CSPP software and supplied to the NWS MKE office in real-time for display in AWIPS.  The image is from 3 July 2012, 07:42 UTC.

Kathleen Strabala CIMSS, Steve Hentz MKX

GOES-R Fog/Low Cloud product over Lake Superior

The GOES-R Fog/Low Cloud product IFR Probability (that is, the probability of visibilities at or below 3 miles), below, shows a pocket of higher values near the coast of Lake Superior in northwest Ontario.  Visible imagery (bottom) confirms the presence of stratiform clouds in this region.  Southwest winds move relatively warm and moist air over the cooler lake surface (Lake SSTs are at or below 50), chilling the air to its dewpoint.   The GOES-R Fog/Low Cloud product fuses Rapid Refresh data and satellite data.

Scott Lindstrom, UW-CIMSS and Steve Hentz NWS-MKX

UW Cloud Top Cooling product and Lightning

The UW Cloud Top Cooling (CTC) product is used at NWS-Sullivan to anticipate (or corroborate) the development of deep moist convection and lightning.  Images above, of cloud-top cooling from Tuesday morning, 3 July 2012, show regions of cooling that occur just before (or concurrent with) the initial lightning strokes.  During the GOES-R era, when temporal resolution is increased, the ability of CTC to anticipate convective development should increase.

Scott Lindstrom, UW-CIMSS and Steve Hentz NWS-MKX

Ice Detection in Hudson Bay using VIIRS data from Suomi NPP

 VIIRS visible imagery (0.68 micrometers) (above) over Hudson Bay, 1801 UTC on 2 July.

VIIRS Snow/Ice Band (1.62 micrometers) (above) over Hudson Bay, 1801 UTC on 2 July

Channels on the VIIRS instrument on board Suomi NPP allow easy discrimination between ice and water clouds.  Ice is a very effective absorber of energy at 1.61 micrometers;  thus, if you compare visible imagery (top) with 1.61-micrometer imagery, regions that are very white in the visible (lots of reflection) and very dark at 1.61 micrometers (lots of absorption, not so much reflection) are assumed to be ice, either at the surface, or in clouds.  In the example above, ice is indicated over central Hudson Bay -- it is very white in the visible, and dark in the 1.61 micrometers.  Similarly, ice clouds are indicated over the southwest part of the image, where clouds are indicated as white in the visible, but not white at all in the 1.61 micrometers.  This is a handy method especially in winter to discriminate between surface snow and water-based clouds.

Scott Lindstrom, UW-CIMSS, Steve Hentz, NWS-MKX

Summer Local Area Testbed 6/19/2012

 This is the CIMSS Cloud Top Cooling image overlaid on the GOES regional scale visible satellite image displayed on AWIPS at 1902Z on June 19th, 2012. The display showed a -9.55C/15 min rate of cooling over Clay County, MN east of Fargo, N.D.

  
 This is the same image combination of visible satellite and CIMSS Cloud Top Cooling at 1915Z with a maximum cooling rate of -26.5C/15 min. over eastern Clay County, MN.

   This the GOES-R ABI Band 10 7.34um water vapor image valid at 18z 06/19/ 2012. Note the minimal highlight over far west-central Minnesota, with convection over northeast North Dakota and across northern Minnesota.

  This is the GOES-R ABI Band 10 7.34um image valid at 19Z 6/19/2012. Notice the pinpoint development of convection along the North Dakota/Minnesota border just northeast of Fargo.

  This is the GOES-R ABI Band 13 image valid at 20Z 6/19/2012. Note the rapid development near Fargo, as well as the more expansive development to the northeast.

 This is the IR image from 2001Z 6/12/2012. Comparing to the ABI Band 13 image above, note the similarity of placement of the cloud shield from the convection near Fargo as well as the cold cloud tops with convection to the northeast, though the actual IR image shows one continuous shield from the two areas, while ABI depicts two distinct areas. The ABI forecast was within one county of the actual development and had an excellent handle on the evolution of the convection in this time period. 

This is the 0.5 degree composite reflectivity image from the KABR WSR-88D at 1857Z 6/19/2012. The cell is developing over southwest Clay County, MN.

 This is the 0.5 degree composite reflectivity image from the KABR WSR-88D at 1902Z 6/19/2012. The cell continued to develop over south central Clay County, MN.The cell eventually strengthened as it lifted to the northeast with composite reflectivity of 55 to 60 dBZ over eastern Clay County at 1920z. The CIMSS Cloud Top Cooling product effectively tagged this cell 18 minutes before it reached peak intensity.

Bob McMahon NWS MIlwaukee/Sullivan WI