More Rain Tonight?

The tropical wave is now over Texas. It is a disorganized system, so it is hard to predict where the rain will be tonight. Let’s look at High-Resolution Rapid Refresh (HRRR), North American Mesoscale Forecast System (NAM), Regional Model (RGEM), and Weather Research and Forecast (WRF-ARW, and WRF-NMM). They are at 0900Z or 4:00 AM CDT.

The HRRR has heavy rain mostly west and southwest of Houston. The NAM has heavy rain over Matagorda Bay and east of Houston. The RGEM has an axis of heavy rain from Corpus Christi area to East Texas. The WRF-ARW has the heavy rain over Matagorda Bay. The WRF-NMM has heavy rain south of San Antonio. This shows that forecasting where heavy rain will fall tonight is all over the place with this tropical wave.

Looking at the most recent Doppler radar mosaic, there is heavy rain over East Texas and Southwest Louisiana. It is not really active right now.

However, with tropical moisture, thunderstorms tend to form at night, especially near the center of the low pressure system. They are called core rains and they can dump heavy rain in a short time. Harvey, Allison, Claudette, and Thrall 1921 Flood were core rain events as flooding rain fell at night. This system is disorganized, so it will be hard to tell where it will exactly form. Some forecast models want the heavy rain over Matagorda Bay, while some have it over Southeast Texas.

Many are wondering what is the forecasted rain amount. The rainfall forecast models are from GFS, Canadian, EURO, ICON, and Weather Prediction Center (WPC). They are all 7 day rainfall total forecast.

The GFS has 4 inches of rain over Galveston Bay. The area of heaviest rain is east of Houston.

The Canadian has nearly 11 inches of rain just north of Houston. The largest area of heavy rain is north of Houston.

The EURO has backed down on nearly 30 inches of rain. It has nearly 15 inches of rain south of San Antonio. There is a large area of heavy rain southwest of Houston.

The ICON has over 13 inches of rain near Aransas Pass. There is an area of 8 inches of rain west of Houston. Most of the heavy rain is over the Gulf Of Mexico.

The WPC has 10 inches of rain over an Matagorda Bay and Victoria. Houston area has 5 to 7 inches of rain.

The rainfall forecast is all over the place on where it will fall and even the amount. This is a very frustrating forecast. Regardless of forecast models, all forecast heavy rain will fall somewhere.

Here is what I think will happen.
-Someone will see heavy rain tonight.
-Not ruling out Houston area getting heavy rain tonight.
-Rainfall amounts could range from 5 to 10 inches of rain with isolated totals approaching and exceeding 15 inches.

The forecast models came from Weather.US, Tropical Tidbits, National Hurricane Center, and National Weather Service. Special thanks to all of them.

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A Weakening Bud And Invest 91L

Oh how the mighty have fallen! Yesterday, Bud was a hurricane. Today it is a tropical storm with 50 mph 44 knots 80 km/h winds. It was once a formidable Category 3 hurricane. All the forecast models have Bud weakening.

With Bud running into cooler water and closer to land, it is most likely to weaken. The next important question is where Bud goes.

The forecast models are having Bud moving towards Baja California and the Southwestern US as a low pressure system. The moisture from Bud is certainly welcomed in the Southwest as they are very dry.

Almost the entire Four Corners is engulfed in a severe drought. It centers around where the Four Corners meet. There is also a severe drought in the Texas Panhandle region. Any rain is welcomed regardless. This leads to Invest 91L in the Caribbean. Many are asking where 91L will go.

Most of the forecast models have Invest 91L heading towards either Mexico or Deep South Texas. Some have it heading towards Southeast Texas. Regardless of where 91L goes, rain will be the main issue. Since Invest 91L is over an area of warm water, does it have a chance of developing?

Most forecast models have 91L at tropical wave or tropical depression. One has it as a tropical storm. Again, it is too early to tell if it will develop. Tropical waves or low pressure areas in the Caribbean and Gulf of Mexico can form suddenly into a tropical storm or even hurricane. It has happened many times in the past. I am not suggesting it will happen with 91L. It is something to consider.

The Tropical Cyclone Formation Probability Guidance Product does give Invest 91L a chance of developing into a tropical cyclone in the next 48 hours. Again, that is only a small chance of developing.

Since, we are on the topic of tropical weather trouble, it brings rain. Various forecast models have different rain amounts, which are from GFS, Canadian, EURO, and Weather Prediction Center (WPC). They are from Weather.US and Weather Prediction Center (WPC)-Quantitative Precipitation Forecasts (QPF). These are 7 day rainfall totals.

The GFS has less rain for Texas and the Southwest. Southeast Texas has 2 to 4 inches of rain. The Southwest sees 0.50 to 2 inches of rain with 6 inches in the mountains.

The Canadian is not particularly generous for the Southwest. However for Southeast, Texas it has up to 8 inches of rain.

The EURO is generous for Southwest and Texas. The mountains of Arizona, New Mexico, and Colorado have up 8 inches of rain. Most of Arizona is wet as well compared to GFS and Canadian.

The WPC has 2 to 4 inches of rain over Southeast Texas. The Southwest has 0.50 to 1 inches of rain with isolated areas seeing 2 inches of rain.

The forecast models are unanimous on that rain will fall in Texas and the Southwest. They diverge on rain amount. Some forecast lesser amounts, while others forecast higher amounts. We should have a better idea of rain amounts later on.

My take on this. Invest 91L is more likely going to be a rain event. I do not expect 91L will develop at this point, but of course anything can happen. I do not think we will see another Harvey event from 91L. It is not forecasted to linger over Texas, like what Harvey or Allison did. As for Bud, the Southwestern US should welcome the rain with open arms. They will need it for sure.

The forecast models came from NCAR-Tropical Cyclone Guidance. The GIS drought map is from United States Drought Monitor.

Hurricane Bud And Invest 91L

NOAA/NESDIS/STAR GOES-16 ABI BAND 11 OR_ABI-L1b-RadF-M3C11_G16_s20181640230401_e20181640241168_c20181640241232.nc

It is June and the tropics are heating up. We have two areas of interests, Hurricane Bud in the East Pacific and Invest 91L in the Caribbean. Let’s start with Bud.

Hurricane Bud was a powerful Category 3 hurricane that weakened into a Category 2 hurricane with 100 mph 85 knots 161 km/h winds. It is due to cooler water Bud is encountering. Cooler water tends to weaken hurricanes even if there is not a whole of wind shear.

The area of warm water in the East Pacific is not that great. However, two major hurricanes have formed so far, which are Aletta and Bud. East Pacific is one of the most active basins despite its small size. As Bud weakens, where does it go? Here is a heat map forecast for Bud.

Most forecast models have Bud heading towards Baja California later by the end of the week. Where it goes after looks to be heading towards the Southwest. They can certainly use the rainfall as they are in a severe drought. The next question is how strong will Bud be?

Most forecast models have Bud as a tropical storm with one as a Category 1 hurricane around the time it us close to Baja California. From there, it is forecasted to weaken to a tropical depression.

The next problem is closer to home, Invest 91L. It is located off the coast of Honduras in the Caribbean. It is right now just a tropical wave with a cluster of thunderstorms. Many are wondering where will 91L will go? Here is a heat map forecast for 91L.

Most of the forecast models have 91L heading towards the Western Gulf of Mexico. One has it heading towards Florida looping around. It is just one forecast model. The forecast models at this time are heading towards Texas. Since this is a tropical wave, the forecast model is subject to change. The $64,000 question is will 91L become a tropical storm or hurricane, which would be Beryl.

Most forecast models keep 91L at tropical depression. Only one has a tropical storm at this time. Intensity forecast models are unreliable, especially if nothing has developed yet. Some factors do favor development. Let’s look at the water around Invest 91L.

The depth of warm water in Caribbean and Gulf of Mexico is great and over a large area. The heat potential is fairly high in the Gulf of Mexico and Caribbean. Warm water is certainly a factor in tropical development, but not the only one.

Wind shear over the Gulf of Mexico is within average and looks to be trending downward. Less wind shear is more favorable for tropical development. If there is strong wind shear over warm water, tropical development is greatly reduced as they blow tops of thunderstorm clouds that forming into something tropical.

At this time, I do not think Invest 91L will develop. It looks to be more of a rainmaker. However, anything can change between now and the end of the week.

The forecast models came from NCAR-Tropical Cyclone Guidance. The tropical heat came from A href=http://www.aoml.noaa.gov/phod/cyclone/data/go.html>Tropical Cyclone Heat Potential (TCHP). Wind shear map came from Tropical Cyclone Formation Probability Guidance Product.

Future Alberto Part 2?

The National Hurricane Center is keeping an eye on Invest 90L. They think in the next 5 days it has a high chance of developing into something tropical.

Interestingly, the intensity forecast keep Invest 90L as a tropical depression. One has it as a tropical storm in 36 hours.

This is not the latest intensity forecast model. It should come out later tonight. The biggest question is where does Invest 90L go?

This is a heat map from data from NCAR-Tropical Cyclone Guidance. The general consensus is it will linger over the Caribbean and possibly move into Mexico or Belize. From there, it goes north. The forecast models tend to congregate around Southeast Louisiana, Mississippi, and Alabama. There is a small risk that Southwest Louisiana and Southeast Texas could get hit by Invest 90L. This is still a rather low confidence forecast of where future Alberto will probably go in the next 5 days.

I would not be surprised we see Tropical Storm Alberto this weekend. The question is where does it go. Everyone in the Gulf of Mexico should keep an eye on Invest 90L. It can go anywhere it wants.

Future Alberto?

The first Invest for the 2018 hurricane season has been tagged as Invest 90L. It is in the Caribbean off the coast of Belize. It is an area of low pressure that is producing a lot of heavy rain. The question is where does it go in the next 5 days.

This is a heat map from data from NCAR-Tropical Cyclone Guidance. It looks like a low confidence forecast as it is all over the place. Some forecast models have it heading towards Alabama. Some have it towards Texas or Florida. It is low confidence because no surface low has formed yet. If a surface low was to form, than we could have a better idea including intensity.

Most forecast models want to keep Invest 90L as a tropical depression. Some want to intensify it to a tropical storm. If 90L is to become a tropical storm, it would be Alberto. I consider the intensity forecast low confidence. Truth is, intensity forecasts are not high confidence for the most part. Forecasting intensity is difficult despite better forecasting technology. I think 90L could become Alberto. Here are my reasons.

Let’s start with the Gulf of Mexico water. The Tropical Cyclone Heat Potential (TCHP) is greatest in the Caribbean, but not so in the Gulf of Mexico. It is May, so the Gulf of Mexico is not going to be this warm.

However, the depth of warm water in the Gulf of Mexico is fairly deep. If the water is very warm at the surface, but not so deep, then that can help weaken tropical cyclone development. If the water is warm, but not super warm, but deep, that is more favorable for tropical development. I would look at depth of warm water more so than surface temperature.

Another factor to look at is wind shear from Tropical Cyclone Formation Probability Guidance Product.

Wind shear over the Gulf of Mexico is below average. More wind shear tends to put a lid on tropical development. Less wind shear is more conducive to tropical development. A tropical wave over very warm and deep warm water with plenty of wind shear is less likely to develop. If it is over not so warm water with low wind shear, it is more conducive to develop into something tropical. Wind shear blows thunderstorm tops off, which inhibits tropical development.

I think Invest 90L could develop this weekend. It bears watching.

A New Normal Part 2

We are living in a new world and reality, a post-Harvey Texas. Just a week ago, a Category 4 monster, Hurricane Harvey was barreling down towards Rockport. Harvey was the first major hurricane to make landfall on America since Wilma in 2005. I think the National Hurricane Center (NHC) may increase Harvey’s peak to 140 mph 224 km/h 122 knots hurricane. Harvey being the first major hurricane to make landfall since Wilma has been largely overshadowed by the epic flooding that ravaged Houston and Beaumont area. That started on the night of August 26, 2017. A series of core rains that form near the center of Harvey.

One good news, the area of thunderstorms in the Southwest Gulf of Mexico does not pose a threat due to wind shear. It is an area of thunderstorms from a tropical wave. However, a cold front that is passing to Southeast Texas could set off thunderstorms and more rain as it picks up moisture from the tropical wave per NWS Houston.

000
FXUS64 KHGX 020220
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
920 PM CDT Fri Sep 1 2017

.UPDATE...
Forecast for tonight looking on track. Updated temps and
dewpoints for trends.

Beat

&&

.PREV DISCUSSION... /ISSUED 628 PM CDT Fri Sep 1 2017/

AVIATION...
Sea breeze and outflow boundary are working their way inland with not
a whole lot of wind changes. SHRA activity that did develop late this
afternoon has now moved away from LBX. Look for light and variable
winds overnight with some patchy MVFR fog possible again at CXO. Expect
VFR conditions tomorrow with mainly light and variable winds. 42

PREV DISCUSSION... /ISSUED 343 PM CDT Fri Sep 1 2017/

DISCUSSION...
Current satellite is showing the typical afternoon cumulus field
developing across southeast Texas. There is a little enhanced
cumulus along the coast but the weak seabreeze is having trouble
generating enough lift for anything more than very isolated and
weak showers. This is expected again tomorrow and the dry weather
is greatly appreciated.

Models are still showing an upper level trough dropping into North
Texas tomorrow night though a significant change is a stronger
ridge over the southern Plains pinching the trough off from the
westerly flow and retrograding it back to the southwest earlier
than previous model runs. A more westerly position of this trough
means weaker lift and lower PoPs for Saturday night and Sunday.

Tropical moisture in the southern Gulf of Mexico will move north
early next week giving us our next decent chance for rainfall. At
the same time, a western U.S. ridge will amplify and northerly
upper flow will drive a cold front through the area Tuesday night
and early Wednesday. The tropical moisture already in place will
interact with this cold front producing a line of showers and
storms along the front. Fortunately the cold front will be moving
fairly quickly, especially for this time of year, pushing the rain
south by Wednesday afternoon. Behind the front, cool and dry air
will filter into the area bringing very pleasant temperatures with
highs only in the lower 80s Wed/Thu.

Hennig

There is also a tropical wave in the far eastern Atlantic that has a good chance of becoming Jose in the next five days. My main concern is Hurricane Irma, which is a Category 3 hurricane out in the Atlantic. Many are wondering where will Irma go. The latest heat map from various forecast models and GFS ensemble track guidance. The GFS goes up to 10 days.

Most forecast models have Irma moving west southwest direction in the next 5 days. From there, based on GFS ensembles, it could go anywhere. Some have Irma going into the Gulf of Mexico and hitting Louisiana in 10 days. Some have Irma hitting Florida to New York. This is too early too tell and this a low confidence forecast. Anything can happen between now and around September 11, which is the 16th anniversary of horrifying terrorist attacks that killed 3,000 people and destroyed the World Trade Center.

Many on social media may have seen this.

That is bogus. For one, the NHC does not issue forecasts 13 days in advance. They only go up to 5 days in advance. Nobody knows where Irma or any hurricane will go in the next 10 days, let alone 5 days.

The latest intensity forecast are in general agreement that Irma will be a major hurricane. A couple have Irma as a Category 2 fluctuating as Category 3, which happens due to eyewall replacement cycle.

I would not be surprised if Irma becomes a Category 5 hurricane, especially when it gets around the Caribbean. Hurricanes in that part of the Atlantic rarely become Category 5 hurricanes. Irma will have to be watched for September.

A New Normal Part 1

Texas and Louisiana are slowly recovering from the ravages of Harvey. It is a national tragedy. Harvey is now a tropical depression over Mississippi dumping heavy rain over Alabama, Mississippi, and Tennessee. They have seen 5 to 8 inches/12.7 to 20.3 centimeters of rain so far. Flooding continues to be a problem for many areas. The Addicks and Barker Reservoir are still bursting at the seams with too much water.

The death toll as of 8/31/2017 is nearly 40. I suspect the death toll is going to be much higher once the flood water recedes. The question is how many. Too early to speculate at this time. If I had to guess, it could be in the hundreds. Katrina claimed more than 1,800 lives, while 9/11 claimed 3,000 lives. 9/11 is a terrorist attack. Harvey could be the deadliest natural disaster since Katrina.

With Harvey no longer a problem, I turn my attention to three areas in the tropics. There are two areas that need to be watched, Hurricane Irma, a low pressure in the Gulf of Mexico, and tropical wave emerging from West Africa. Let’s start with Irma.

Irma is now a major hurricane with 115 mph 184 km/h 100 knots with gusts of 145 mph 232 km/h 126 knots. It is moving westward at this time. Many are wondering where will Irma go. Will Irma enter the Gulf of Mexico, make landfall on the East Coast, or become a fish storm? The latest heat map from various forecast models and GFS ensemble track guidance. The GFS goes up to 10 days.

The forecast models at this point do not have have it getting close to Texas. Some have Irma entering the Gulf of Mexico and hitting the Florida Panhandle. It looks to be a East Coast threat at this point. New York City area is included in the risk area. Again, this is 10 days from now and anything can change between now and next week. Since Irma is a major hurricane, the intensity forecast is interesting.

Most maintain Irma as a Category 3 hurricane. One has it as Category 4 hurricane in two days. Some have Irma as a Category 4 hurricane in three days. I think Irma has the potential to intensify into a Category 5 hurricane, especially when it gets closer to the Caribbean. Irma could be a problem starting next week as it gets closer to land. Irma needs to be watched closely.

Another area of concern is in the Southwest Gulf of Mexico. Here is a discussion from National Hurricane Center (NHC)

ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Thu Aug 31 2017

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Hurricane
Irma, located over the eastern Atlantic Ocean. The Weather
Prediction Center is issuing advisories on Tropical Depression
Harvey, located over northern Mississippi.

1. A tropical wave emerging over the far eastern Atlantic is moving
westward at about 15 mph. Environmental conditions are expected to
become more conducive for development over the weekend and early
next week while the system moves well to the south and southwest of
the Cabo Verde Islands.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...40 percent.

2. A area of low pressure could form over the southwestern Gulf of
Mexico by the weekend, however, environmental conditions are
expected to become unfavorable for tropical cyclone formation by
that time. Interests along the Texas and Louisiana coasts are
encouraged to consult products from their local NWS Forecast Office
for more information about impacts from any non-tropical weather
systems.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...10 percent.

Public Advisories on Harvey are issued under WMO header WTNT34 KWNH
and under AWIPS header TCPAT4.

Forecaster Zelinsky

I do no think that will develop into something tropical. However, the moisture from it could be a factor for next week as a cold front passes. The cold front could trigger storms in areas that have been flooded. Not a good thing. That will also have to be watched.

Lastly, there is a tropical wave emerging out of West Africa. I think it will be tagged with an Invest in the next couple of days. It has a moderate chance of developing in the next five days. I would not be surprised if this becomes our next named storm, which would be Jose.

Here is what I think will happen.
-The area of thunderstorms in Southwest Gulf of Mexico bears watching, but I do not think it will develop.
-Irma needs to be watched and may pose a threat somewhere.
-Tropical wave emerging from West Africa needs to be watched. Could be Jose.

The forecast models came from NCAR-Tropical Cyclone Guidance and National Hurricane Center. Special thanks to all of them.

This is going to be a long road to recovery. It is a new normal for Texas.