Alberto Nearing Hurricane Strength

Subtropical Storm Alberto is getting stronger as it nears land. At this hour, Alberto has strengthened and now has maximum sustained winds of 65 mph and pressure is down to 991 mb. Rain bands are rotating into South Carolina, Georgia, Alabama, and Florida this afternoon with tropical storm force wind gusts being experienced across parts of Florida as Alberto moves to the northwest at 10 mph. Tropical storm force winds can be expected across southern and western parts of Georgia, Alabama, and southern and western Mississippi throughout the day on Monday (see Fig. 1).

Fig. 1: Tropical Storm Force Winds Forecast

As Alberto continues its north-northwest movement throughout the overnight hours, a transition to a tropical (warm core) entity is possible. This is evident on the latest satellite imagery, which shows Alberto becoming more symmetric with thunderstorms around the center of circulation (see Fig. 2). This should allow for the possibility of continued slight strengthening over the next 12 hours.

Fig. 2: Satellite Imagery

Regardless of intensity, Alberto will bring an enhanced flash flood threat to the Southeast, gusty winds, storm surge and rip currents, and isolated tornadoes to the region. This greatest threat with Alberto is the rainfall. As Alberto moves inland Monday afternoon (around 1:00PM), likely between Pensacola, FL and Panama City, FL (see Fig. 3) as at least a 65 mph tropical storm, Alberto will begin to slow in forward speed. This will create a widespread area of 2-6″ of rainfall across much of the Southeast and southern parts of the Ohio Valley through mid-week. A few areas will see rainfall amounts between 6 to 12 inches (see Fig. 4).

Fig. 3: NHC Track Forecast

Fig. 4: WPC Precipitation Forecast Through 7 Days

Please remain alert as Alberto approaches the Gulf Coast. Updates will be provided as needed.

Alberto Nearing Gulf Coast

Subtropical Storm Alberto is getting closer to land as it moves towards the north-northwest at 12 mph. At this hour, Alberto remains a Subtropical Storm with maximum sustained winds of 50 mph. Rain bands are rotating into South Carolina, Georgia, Alabama, and Florida this afternoon with tropical storm force wind gusts being experienced across parts of Florida. Tropical storm force winds can be expected across southern and western parts of Georgia, Alabama, and southern and western Mississippi throughout the day on Monday (see Fig. 1).

Fig. 1: Tropical Storm Force Winds Forecast

As Alberto continues its north-northwest movement throughout the afternoon and overnight, a transition to a tropical (warm core) entity is possible. This is evident on the latest satellite imagery, which shows Alberto becoming more symmetric with thunderstorms around the center of circulation (see Fig. 2). This should allow for the possibility of slight strengthening over the next 12 hours. The main hinderance of greater intensification is the dry air to the west of Alberto.

Fig. 2: Satellite Imagery

Regardless of intensity, Alberto will bring an enhanced flash flood threat to the Southeast, gusty winds, storm surge and rip currents, and isolated tornadoes to the region. This greatest threat with Alberto is the rainfall. As Alberto moves inland Monday afternoon (around 1:00PM), likely between Pensacola, FL and Panama City, FL (see Fig. 3) as at least a 65 mph tropical storm, Alberto will begin to slow in forward speed. This will create a widespread area of 2-6″ of rainfall across much of the Southeast and southern parts of the Ohio Valley through mid-week. A few areas will see rainfall amounts between 6 to 12 inches (see Fig. 4).

Fig. 3: NHC Track Forecast

Fig. 4: WPC Precipitation Forecast Through 7 Days

Please remain alert as Alberto approaches the Gulf Coast. Updates will be provided as needed.

Subtropical Storm Alberto

Subtropical Storm Alberto formed in the western Caribbean this morning. Alberto will track northward into the Gulf of Mexico through the holiday weekend; wreaking havoc across much of the Southeast in the form of flooding, storm surge, tornadoes, and high winds (see Fig. 1).

Fig. 1: National Hurricane Center Forecast

At this hour, Subtropical Storm Alberto has maximum sustained winds of 40 mph and moving to the E at 2 mph. Alberto is expected to transition from a subtropical cyclone to a tropical cyclone over the weekend as environmental conditions become more favorable. “Subtropical” essentially is a hybrid between a mid-latitude cyclone (cold core) and a tropical cyclone (warm core). Just because the named cyclone is a “subtropical” entity at this time, it needs to be taken extremely seriously because the same impacts as a tropical storm or low-end hurricane can be felt and are expected across parts of the Southeast.

There are high shear values across the southern Gulf of Mexico and Caribbean, which is causing Alberto to have a unique satellite appearance. Much of the convection (thunderstorms) is east of the center of the storm (see Fig. 2). This is of importance because this convection will move into Florida and other parts of the Southeast–causing flash flooding. Another important factor that may enhance flooding is a building high to the north of Alberto. This high may act to ‘trap’ Alberto across the Gulf States early next week. Widespread heavy rainfall is possible (see Fig. 3) in which some areas may see 8-14″ of rainfall. All areas east of the Mississippi River across the Southeast have a chance to see flooding due to Alberto from this weekend into at least mid-week next week.

Fig. 2: Current Satellite Imagery

Fig. 3: WPC Rainfall Forecast Through 7 Days

Over the next 36-48 hours, Alberto will continue to move northward. Tropical storm impacts will be felt by Sunday morning for the Gulf Coast States and Alberto should be close to land by Monday. Alberto will slowly continue to increase in intensity during this time period as environmental conditions becomes more favorable for intensification (less shear and anomalously warm waters in the northern Gulf) allowing to the transition to a warm core high end tropical storm or low-end hurricane.

A Tropical Storm Watch is now in place for portions of the northern Gulf Coast of the United States. This extends from Indian Pass, Florida, westward to Grand Isle, Louisiana. Please begin to prepare for tropical impacts from this system if you live along the Gulf Coast. Updates will be provided as needed.

Fig. 4: Current Tropical Storm Watches

NOAA Says Near To Above Average 2018 Atlantic Hurricane Season

NOAA is forecasting a near to above average 2018 Atlantic Hurricane Season (see Fig. 1). This is coming off of the heels of an above average season last year for the Atlantic, which featured 17 named storms. Of those 17 named storms, 10 were hurricanes. Factoring into the NOAA forecast are the possibility of a weak El Nino and near average Sea Surface Temperatures (SSTs). Research shows these two factors can be favorable for the genesis of tropical cyclones.

NOAA’s forecast calls for 10-16 named storms with 5-9 of these named storms being hurricanes. Their forecast is similar to Colorado State University’s (CSU) forecast from a few weeks ago, which calls for 14 named storm and 7 hurricanes. The 30-year average (1981-2010) for named storms is 12 and the 30-year average for hurricanes is 6.

Fig. 1: 2018 Atlantic Hurricane Season Forecast

Please keep in mind, regardless of the number of named storms, it only takes one landfalling storm to cause tremendous impacts. Currently, Firsthand Weather is keeping a close eye on the Gulf of Mexico for the potential of the first tropical cyclone of the year. See the latest HERE!

Entire Gulf Coast Needs To Stay Alert!

The official start of the Atlantic hurricane season is still a week out (June 1st) but that is not slowing things down. A surface low is currently spinning near the Yucatan Peninsula. The National Hurricane Center (NHC) has given this area of low pressure a 60% chance of development (see Fig. 1) over the next five days. This low will move into the southern Gulf of Mexico late this week and move towards the northern Gulf Coast of the United States by the weekend.

Fig. 1: NHC Graphic

Numerical guidance is struggling with the track and intensity of this low, but regardless of intensity, heavy rainfall will impact parts of the Southeast. This low may develop into a tropical depression or low-end tropical storm over the weekend. The European, CMC, and NAM are all indicating this is a possibility. Sea-surface temperatures (SSTs) in the Gulf are marginal right now but above average SSTs exist across much of the northern Gulf of Mexico (see Fig. 2). The wind shear is currently strong (see Fig. 3), which is aiding in preventing this low to develop quickly. This shear should lessen by late week into the weekend (see Fig 4), which is why the NHC has given this low a 60% chance of development.

Fig. 2: Current SST Anomalies

Fig. 3: Current Wind Shear

Fig. 4: Future Wind Shear (GFS: Friday Afternoon)

Right now, the best region to see the track of the center of the low is from Pensacola, FL to New Orleans, LA by late weekend into early next week (see Fig. 5). Regardless of the track of the center of the low and intensity, very heavy rainfall is likely for parts of the Southeast from lat week into early next week. The best chance for heavy rainfall exists across the northern Gulf Coast and east of the Mississippi River (see Fig. 6).

Fig. 5: Latest Spaghetti Plot

Fig. 6: WPC Rainfall Map Through 7 Days

Some areas may see flash flooding and rainfall amounts in excess of 6-12″. A few damaging wind gusts and weak tornadoes may occur, too. This situation is fluid and evolving so keep checking back for updates to this forecast. All states along the Gulf (from Texas to Florida) need to keep a close eye on the forecast.

Disturbance in the Gulf of Mexico Will Bring Heavy Rain and Muggy Weather

Ridging has continued to build over the southeastern quadrant of the United States over the last few days, which has been responsible for a large region of anomalously hot temperatures and drier air. This ridge is currently centered over eastern Arkansas and western Tennessee but will begin to split as a mid-to-upper level closed low moves from the eastern Gulf of Mexico and into the Southeast early next week. Given that ridging is associated with sinking air which often limits storm development, the splitting of this ridge will result in a drastic change in sensible weather conditions in the coming days.

The National Hurricane Center has outlined a disturbance in the eastern Gulf of Mexico and is giving it a 40% of tropical or subtropical development over the next 5 days. Even though the Atlantic hurricane season doesn’t technically begin until June 1, it wouldn’t be a big surprise to see a weak subtropical/tropical disturbance develop, if convection (thunderstorm development) can consolidate over a small enough region in the Gulf. The upper-level trough/closed low (the feature that is splitting the ridge over the Southeast) will continue interacting with a region of broad surface low pressure moving into the Gulf, which should assist in its further development since the upper-level dynamics will be supportive. Whether or not we get our first named system out of this is not necessarily important from a sensible weather standpoint. The impacts will be about the same regardless, which is what the primary focus should be on.

5-day NHC tropical outlook

Let’s talk about potential impacts and how the weather should change compared to last week/this weekend. The mid-south (Louisiana, Arkansas, most of Mississippi, most of the Southern Plains, and areas just northward) will remain quite toasty for a large part of the week since the closed low and developing surface low should remain to the east/southeast of those regions. However, farther east, temperatures should be cooler due to enhanced rainfall for most of the week, but the transport of deeper moisture into the area will result in muggy conditions, making temperatures feel warmer. Instead of trying to put all of this into words, take a look at the map from the Weather Prediction Center (NOAA) that shows the projected rainfall totals over the next 5 days. Don’t focus as much on exact amounts, but take note if you’re located in a region that is expected to get more than a couple of inches of rain (purplish/reddish-shaded regions).

5-day wpc rainfall forecast

The big impact will be the heavy rainfall, although that’s not necessarily a bad thing since many areas have recently been dry. However, be wary if flash flooding begins to occur and do not attempt to drive over any flooded roadways. As the rainfall map indicates, heaviest rainfall totals over the next several days should occur from Florida through Georgia, parts of Alabama, the Carolinas, and up the East Coast. Another zone to keep an eye on will be from the Ohio Valley into the Mid-Atlantic, where a frontal boundary will remain stalled out over the region. Given that this region is located along the periphery of the current ridge, winds have been westerly/northwesterly through a deep layer of the atmosphere, and disturbances will continue to be embedded within the westerlies, so storminess may be a bit more intermittent and hit-or-miss across that area. Also, this is where the severe weather threat (mainly a damaging wind threat) will be concentrated this week, along with a severe weather threat across parts of the Great Plains. Firsthand Weather will address those risks on a day-to-day basis. Partially due to the moistening of the environment through a deep layer farther south across the Southeast, this should mostly limit the severe weather risk, since temperatures will not decrease with height as rapidly (resulting in lower instability). We’ll still keep an eye on it just in case though.

To briefly summarize, expect a change in weather conditions across a large region. Many will be transitioning from a dry and hot pattern to a warm, muggy, and wet pattern. Given the position of the large ridge, the low in the Gulf of Mexico will not be in a hurry to move out and will have to be swept out by an incoming trough later in the week. This is particularly important information to keep in mind if you intend on hitting the water for fishing or other watersports activities. These towers way north of Key West in the gulf are a prime location for fishing but will be buffeted by the weather so be sure to stay safe. In the meantime, get used to the wet (or at the least, muggy) weather!