Impacts of high-frequency radar-derived wind observations on COAMPS® forecasts

I recently submitted a proposal for the National Research Council Research Associateship Program (http://sites.nationalacademies.org/pga/rap/). The proposal is to work at the Naval Research Laboratory in Monterey, California as a post-doctorate researcher on a data assimilation project.

The full application can be found here: https://1drv.ms/b/s!AtJL0JL_rT9judo3fc85wl5SkgOIiQ

Abstract

Shore-based high-frequency (HF) radars are routinely used to observe ocean currents and surface wave characteristics remotely. Because surface waves are closely related to near-surface winds, many investigators have explored methods in deriving winds from HF radars, with limited success until now. Most recently, a technique has been developed that uses HF radar Doppler spectra data with the adjoints of a HF radar model and a wave prediction model to derive winds. This technique has been applied to HF radar data collected along the Santa Barbara, California coast during October 2017. These remotely sensed near-surface wind observations are likely to be valuable in initializing mesoscale analyses and forecasts in the littoral zone, as satellite-derived surface winds are generally not available near the coast. Since ocean wave models are dependent on atmospheric winds, better forecasts of near-surface winds impact almost all Naval operations near shore—especially transits in and out of ports. This work proposes to investigate the impact HF radar-derived winds have on the quality of Coupled Ocean/Atmosphere Mesoscale Prediction System® (COAMPS) analyses and forecasts using the new COAMPS-4D Variational data assimilation system. An observing system experiment is proposed to evaluate impacts from real HF radar observations on COAMPS followed by a historical observing system simulation experiment to determine potential impacts from simulated wind retrievals.

FIG. 1 Southern California coast surface wind observation network available 14 October 2017. Locations of the HF radar network are denoted by green triangles and automated weather stations and buoys are denoted by red dots.

FIG. 2 Observed near-surface vector wind at 17:25 UTC 14 October 2017 from MetOp-B ASCAT scatterometer (black) and automatic weather stations and buoys (red). Half and full barbs denote 2.5 and 5 m s^-1, respectively.

Summer Thunder

I woke up last night at 11:40 to strobing lights. A long line of thunderstorms stretched from Richfield to the Utah-Idaho border. This morning I measured 0.26 inches of rain in south Provo.

Radar 11:50 PM, Local Time

It was a forecast miss for the HRRR model, which didn't simulate this particular line of thunderstorms until the analysis hour. This is an important lesson on not using weather models as deterministic forecasts for thunderstorm prediction. This loop of HRRR forecasts shows all 18 forecasts and the analysis valid at 0600 UTC (local midnight). Beyond the first two hours, there is no warning of this particular line of storms.

Started a small fire on Y-Mountain: https://www.heraldextra.com/news/local/central/provo/lightning-sparks-small-brush-fire-on-y-mountain/article_ad4d2531-58a6-5b62-800e-0e38e3be22ca.html

Gusty winds were observed across the state. The Salt Lake International Airport and many other locations along the Wasatch Front recorded winds exceeding 50 MPH between 11 and Midnight last night.

In Spanish Fork, recorded winds gusted ranged between 17 and 30 MPH.

UKBKB (bench): Max gust 17 MPH at 11:35 PM

C9348 (bench): Max gust 18 MPH at 11:33 PM

UCC13 (river bottoms): Max gust 30 MPH at 11:15 PM

KSLC (Salt Lake City International Airport): Max gust 50.6 MPH at 11:20 PM

Quarter-Sized Hail

Quarter-sized hail was observed in this quick-moving thunderstorm that moved across the Salt Lake Valley before noon...

Radar 10:45 AM

Camera 10:55 AM

GOES-16 True Color Image and Lightning data 10:43 AM

It looks to me that the lightning data is skewed a little south of there it actually occurred. The center of maximum reflectivity is in the heart of Salt Lake County, but the lightning mapper positioned the flashes along the Salt Lake-Utah county line.

Doppler on Wheels Returns

A Doppler on wheels came back to the University of Utah. Here is a picture of me today, and from 2011 when I first saw one of the storm-chasing machines.

19 November 2017

27 October 2011

HRRR "Hovmoller" Forecasts

Hovmoller diagrams have been used to show wave propagation over space and time. By changing the dimensions of these diagrams to a valid-time/forecast-time dimension, then these kind of plots can be useful to show an ensemble of model forecast results at a point.

For example, here is a "Hovmoller" diagram showing the HRRR forecasted temperature at the Salt Lake International Airport for two days. The observed air temperature is shown at the bottom and look almost like a bar code.

From this figure we can see how air temperature changes across the time period. Reading the figure from left to right and looking at all forecast hours (vertical columns), the temperature is generally cooler at night and warmer in the day with July 4th being forecasted as a hotter day than July 3rd.

A single model run can be read diagonally. For example, pick an analysis hour, then look at the 1-hour forecast by moving one box up and one box right. You can see that some model runs were cooler than other.

Next, we can look at how each model run differed from each other by reading a column from top to bottom, and see how the HRRR forecasts changed between successive model runs. This is useful for determining the likelihood for certain atmospheric conditions.

Now, in real-time operations you don't have all the HRRR data for the rest of the day. The Hovmoller plots instead look like this, with missing data because those HRRR models haven't run yet.

This figure shows forecasted wind speed at Antelope Island (station ID UFD09) for a 24 hour period on July 5th. The contours indicate stronger higher wind speeds forecasted within a 54x54 km box centered at UFD09. Again, the white is the missing information because those HRRR simulations have not run yet. 

You'll see that the latest HRRR run is showing strong winds for a period of time that were not previously forecasted. This may likely be a result of new data assimilated into the HRRR model leading to a greater chance of strong winds. In this case, this particular model run formed a thunderstorm in the area, causing a downdraft and stronger winds in the vicinity as shown in the Reflectivity Hovmoller...

No composite reflectivity was forecasted in any other model run except for the most recent two. There was higher reflectivity in the vicinity as shown by the contours. For this case, there was little warning of a possible storm activity at Antelope Island (at the time of my writing, there has not been a convective system develop over Antelope Island).

A Hovmoller for Spanish Fork (station ID UKBKB) the HRRR forecasts show a greater potential for storm activity while more successive runs are indicating some convective activity for the rest of the afternoon and evening.

There has been some storm activity near Spanish Fork at this time, but mostly in the surrounding mountain area.

Another example of using the HRRR Hovmoller forecast fires to determine the potential for storm activity is from the Burro Fire...

A storm never developed directly over the fire at 21:00 UTC, but there was some other convective activity in the surrounding area.

What we learn: Forecasting for convective outflows in the HRRR model is difficult, especially when you want to pin-point when and where convection will occur. Convective outflows are hard to forecast even an hour or two before they occur, because the time scale of these clouds form are short--less than an hour. A probabilistic approach is most useful for forecasting these events. The ensemble forecast approach should consider an offset  in storm location and timing for such events. In the above Hovmoller for reflectivity for the Burro fire, I would know that convective activity is possible, more so in the vicinity, but not certain. As a fire manager, I would be need to be more aware of convective situations that could potential make firefighting more difficult.

Hurricane Matthew: Buckets of Rain

Fayetteville, North Carolina, recorded nearly 15 inches of accumulated rain in a 24 hour hour period on October 8th. This large rain event was due to heavy rain from Hurricane Matthew. Below is the radar at 1620 UTC.

Volunteer weather rangers from the CoCoRaHS network shows the high rain totals in North Carolina, especially Cumberland County.

My dad was on a trip in North Carolina, and his plane home was canceled because of the hurricane.

Rain and Hail in Spanish Fork

It's raining and hailing in Spanish Fork...

Time: 18:50 UTC

You can see the cooler air accompanied by the storm from the temperature and dew point time series...Temperature goes down, and wet bulb (humidity) goes up. When the temperature and dew point temperature are the same that is about all the cooling that can be done by evaporation...a natural air conditioner.

There is some good cloud development shown up in the satellite images...

Time: 18:56 UTC
weather.cod.edu

One interesting aspect of this storm is how the HRRR model handles it. The latest analysis hour has the reflective in the right spot, but the HRRR model gets rid of the storm by the first forecast hour. The storm has lasted into that hour, and so this is a case that the HRRR model is not useful for a short term forecast of this storm.

Time: 17:00 UTC

 Now look at the one hour forecast...the hail storm has disappeared. Yep, not really a useful short-term forecast.

Time: One hour forecast valid at 18:00 UTC

Quick Hail Storm

Quick and heavy hail storm in Salt Lake just moments ago...

The crane on campus switched directions, a sure sign that the gust front just passed

And down came the hail!

Spring Downpour and Waiting for a Train

FrontRunner trains were delayed yesterday afternoon. There were lots of people waiting in the rain at Murray Station.

Finally, the train came. Standing room only.

Murray Station at the red star

The storm was moving southeast. While skies to the east were dark, the skies in the near west were clear and sunny! This neat picture of the hospital shows the sunny reflection in the windows with the dark skies in the background.

The Mountain Meteorology Lab camera captured a nice rainbow.

Strong Winds

Strong winds in northern Utah this morning preceding a winter storm. Shown below is wind speed and wind gusts in mph.

Looks like the cold front and precipitation is on it's way...

Right now the Cold Front is at Dugway. Look at the drastic temperature contrast! On the east side of the front temperatures are at 10 C, warm enough to get away with a jacket. On the west side of the front in the cold air, temperatures are at 2 C, near freezing!

From the HRRR, looks like the front is expected to reach the Salt Lake Valley between 12:00 and 1:00.

Flying home with hopefully without delays

Flying home this evening, hopefully without delays. Here's the HRRR simulated radar for the time we'll be in the air...

Update: Getting a little closer to our flight... In the short term, it doesn't look like any thunderstorms will affect our flight. We have been delayed. Must for some other reasons.

In the mean time, I'm announcing my Simple Weather maps. It uses recent weather observations collected by MesoWest and plots the temperatures on a map. When you load the webpage you it will locate where you are at and show you a map of current temperatures. You can also move the map around and click a new area to populate the map with more weather stations. Check it out here: http://home.chpc.utah.edu/~u0553130/Brian_Blaylock/map.html

Flight to Denver

I'm on my way to Boulder Colorado for a workshop and conference for the SONGNEX campaign. I'm going to give a presentation on weather conditions in the Uintah Basin during their study period.

Our flight was delayed because our plane coming from Las Vegas was help up by the thunderstorms. It should be here soon to take us to Denver. Looks like we'll fly around some thunderstorms in the Colorado.

The storms seemed to miss us on our drive to Boulder. The Front Range welcomed us with this pretty sunset...

Thunder and morning clouds

Last night was the first time in a long time when lightning woke me up in the middle of the night. Around 4:30 AM my dark bedroom flashed with light, followed by a loud crack from outside. I ran upstairs to watch the storm pass. It rained for about 30 minuets.

Radar image at 4:45 AM local time

Rain accumulation at my station in Spanish Fork. Rain started around 4:40 and ended around 5:00 Am

The storm has since moved north. My sister and mom shared this picture with me of the clouds in the morning looking west.