Diana Leonard
@hazardwriter.bsky.social
Science writer covering weather, climate change and hazards in CA and the West. Frequent WashPost/Capital Weather contributor.
Reposted by Diana Leonard
This was fun to write! But also one of the more complex topics that I’ve covered!
The polar vortex is about to weaken sharply, as part of a rare event called “sudden stratospheric warming.” It’s a big deal for weather around the country.
Rare stratospheric warming event is about to occur. Here's the California impact
The polar vortex is about to weaken sharply, as part of a rare event called “sudden stratospheric warming.” It’s a big deal for weather around the country.
bit.ly
November 19, 2025 at 8:16 PM
This was fun to write! But also one of the more complex topics that I’ve covered!
Reposted by Diana Leonard
An unusually strong storm system will bring widespread rain to southern California through Sunday. The period of most concern is tonight through Saturday night when a large area of heavy rain and isolated but potentially severe thunderstorms will bring a moderate risk of...
(1/2)
(1/2)
November 14, 2025 at 5:03 PM
An unusually strong storm system will bring widespread rain to southern California through Sunday. The period of most concern is tonight through Saturday night when a large area of heavy rain and isolated but potentially severe thunderstorms will bring a moderate risk of...
(1/2)
(1/2)
Reposted by Diana Leonard
1/3) Model Guidance tools continue to disagree on details, but they do agree that #SoCal will see periods of moderate to heavy rainfall between late Thursday night and Sunday as the system slows down, cuts off and stalls near the area before moving East, with another storm on its heels for Monday...
November 12, 2025 at 8:02 PM
1/3) Model Guidance tools continue to disagree on details, but they do agree that #SoCal will see periods of moderate to heavy rainfall between late Thursday night and Sunday as the system slows down, cuts off and stalls near the area before moving East, with another storm on its heels for Monday...
Reposted by Diana Leonard
NOAA cut funding for critical parts of the tsunami and earthquake detection system in Alaska, primarily in the Aleutians. I spoke to Wash Post about negative impacts. But, hey, what are the chances of a deadly tsunami being triggered in Alaska? (Gift article, not behind paywall) ⚒️ wapo.st/4qKvavQ
This lab is key for tracking deadly waves. Its sensors are about to go offline.
After NOAA cut funding to the lab that’s been monitoring seismic activity for more than 25 years, nine stations tracking tsunami-causing earthquakes for the agency will go offline by the end of the mo...
wapo.st
November 11, 2025 at 7:37 PM
NOAA cut funding for critical parts of the tsunami and earthquake detection system in Alaska, primarily in the Aleutians. I spoke to Wash Post about negative impacts. But, hey, what are the chances of a deadly tsunami being triggered in Alaska? (Gift article, not behind paywall) ⚒️ wapo.st/4qKvavQ
Reposted by Diana Leonard
Thrilled to work with @wxmanms1.bsky.social, whose Substack I've read and admired for some time, on this piece on #Melissa www.nytimes.com/2025/10/29/o...
Opinion | In 40 Years of Forecasting, I’ve Never Seen a Hurricane Like Melissa
www.nytimes.com
October 29, 2025 at 4:12 PM
Thrilled to work with @wxmanms1.bsky.social, whose Substack I've read and admired for some time, on this piece on #Melissa www.nytimes.com/2025/10/29/o...
Reposted by Diana Leonard
In less than 24 hours, Melissa went from a tropical storm to a Category 4 hurricane, an extremely fast and rare intensification.
Here’s how it became so strong by the time it hit Jamaica:
Here’s how it became so strong by the time it hit Jamaica:
The dangerous combination that made Melissa a monster hurricane
Hurricane Melissa’s power was undeniable, intensifying faster than most storms on record.
www.washingtonpost.com
October 29, 2025 at 5:00 PM
In less than 24 hours, Melissa went from a tropical storm to a Category 4 hurricane, an extremely fast and rare intensification.
Here’s how it became so strong by the time it hit Jamaica:
Here’s how it became so strong by the time it hit Jamaica:
Reposted by Diana Leonard
Melissa is the worst Atlantic storm you could imagine, and it’s making landfall in Jamaica as I write this. Very few places on the planet have experienced conditions like some portions of Jamaica will in the coming hours. Our thoughts are with the Caribbean. Details below or at theeyewall.com.
Melissa is now a top 5 storm all-time, and it is about to make landfall in Jamaica
Jamaica is experiencing impacts that few places have ever experienced from a hurricane
open.substack.com
October 28, 2025 at 4:28 PM
Melissa is the worst Atlantic storm you could imagine, and it’s making landfall in Jamaica as I write this. Very few places on the planet have experienced conditions like some portions of Jamaica will in the coming hours. Our thoughts are with the Caribbean. Details below or at theeyewall.com.
Reposted by Diana Leonard
Side-by-side geostationary images (visible to left, infrared to right) since sunrise highlight category 5 Hurricane Melissa's painstakingly slow motion over extremely warm water. Despite its current proximity to Jamaica, landfall isn't expected until **tomorrow morning**.
October 27, 2025 at 2:02 PM
Side-by-side geostationary images (visible to left, infrared to right) since sunrise highlight category 5 Hurricane Melissa's painstakingly slow motion over extremely warm water. Despite its current proximity to Jamaica, landfall isn't expected until **tomorrow morning**.
Reposted by Diana Leonard
"Damaging winds and heavy rainfall... will cause catastrophic and life-threatening flash flooding and numerous landslides before potentially devastating winds arrive... Extensive infrastructural damage, long-duration power and communication outages, and isolation of communities are expected." 💔😔
October 26, 2025 at 4:37 PM
"Damaging winds and heavy rainfall... will cause catastrophic and life-threatening flash flooding and numerous landslides before potentially devastating winds arrive... Extensive infrastructural damage, long-duration power and communication outages, and isolation of communities are expected." 💔😔
Reposted by Diana Leonard
An atmospheric river followed by a Pacific storm will bring periods of gusty winds with low elevation heavy rain and high elevation snow to parts of the northwestern U.S through the weekend.
Check weather.gov for the latest forecast.
Check weather.gov for the latest forecast.
October 24, 2025 at 5:22 PM
An atmospheric river followed by a Pacific storm will bring periods of gusty winds with low elevation heavy rain and high elevation snow to parts of the northwestern U.S through the weekend.
Check weather.gov for the latest forecast.
Check weather.gov for the latest forecast.
Reposted by Diana Leonard
Did a dive into the forecast for #Melissa and potential for catastrophic Caribbean impacts. Also discussed longer term expectations including a non-zero risk to parts of eastern North America as we watch the evolution of a pivotal upper trough next week. https://tinyurl.com/mrbx366b
Increasing likelihood that Melissa will produce catastrophic impacts in parts of the Caribbean
Slow movement of an intensifying and enlarging (eventual) hurricane means prolonged and potentially massive impacts, with Jamaica and parts of Haiti most under threat initially.
tinyurl.com
October 24, 2025 at 3:00 AM
Did a dive into the forecast for #Melissa and potential for catastrophic Caribbean impacts. Also discussed longer term expectations including a non-zero risk to parts of eastern North America as we watch the evolution of a pivotal upper trough next week. https://tinyurl.com/mrbx366b
Reposted by Diana Leonard
Persistant dry and breezy weather is creating favorable conditions for wildfire growth and spread across areas east of the Appalachians this week.
October 22, 2025 at 7:10 PM
Persistant dry and breezy weather is creating favorable conditions for wildfire growth and spread across areas east of the Appalachians this week.
Reposted by Diana Leonard
A low-pressure system moves down the West Coast, bringing stormy weather to California.
October 14, 2025 at 4:51 PM
A low-pressure system moves down the West Coast, bringing stormy weather to California.
Reposted by Diana Leonard
A cold storm will soak much of California early this week and bring widespread rain, heavy Sierra snow and flood risks near recent burn scars in the southern part of the state.
Storm expected to soak much of California early this week
Along with the widespread rain, there are flood risks near recent burn scars in Southern California.
www.washingtonpost.com
October 13, 2025 at 4:30 PM
A cold storm will soak much of California early this week and bring widespread rain, heavy Sierra snow and flood risks near recent burn scars in the southern part of the state.
Reposted by Diana Leonard
1/2) HRRR Model's Simulated Radar depiction through Tuesday PM - A potent Cold Front will bring periods of Rain with embedded Thunderstorms to #SoCal beginning tonight through tomorrow. The potential exists for squalls of intense rainfall reaching as far South as SD County. #CAwx
October 13, 2025 at 7:57 PM
Reposted by Diana Leonard
Moisture associated with Priscilla will lead to a significant heavy rainfall and a flash flood risk across portions of Arizona, southern Utah, southwest Colorado, and far northwest New Mexico through Saturday.
(1/2)
(1/2)
October 9, 2025 at 4:00 PM
Moisture associated with Priscilla will lead to a significant heavy rainfall and a flash flood risk across portions of Arizona, southern Utah, southwest Colorado, and far northwest New Mexico through Saturday.
(1/2)
(1/2)
Reposted by Diana Leonard
10/2/25 10:25am
No snow yet but plenty of rain over the last 24 hours, which is a great start to the 2026 water year that began yesterday.
These early rain storms help prime our soil and keep it moist meaning less water from our snow has to do that job later.
#CAwx #CAwater
No snow yet but plenty of rain over the last 24 hours, which is a great start to the 2026 water year that began yesterday.
These early rain storms help prime our soil and keep it moist meaning less water from our snow has to do that job later.
#CAwx #CAwater
October 2, 2025 at 5:29 PM
Reposted by Diana Leonard
September 18, 2025 at 7:52 PM
Reposted by Diana Leonard
Tropical moisture and rainfall is ongoing across the Southwest, with flash flooding possible today and Friday (September 18-19). A Flood Watch is in effect due to the potential of flooding of rivers, creeks, streams, and other flood-prone locations - low water crossings may be flooded.
weather.gov
weather.gov
September 18, 2025 at 4:15 PM
Tropical moisture and rainfall is ongoing across the Southwest, with flash flooding possible today and Friday (September 18-19). A Flood Watch is in effect due to the potential of flooding of rivers, creeks, streams, and other flood-prone locations - low water crossings may be flooded.
weather.gov
weather.gov
Reposted by Diana Leonard
Flood Watch issued for a good chunk of SoCal. #floodwatch #cawx #flooding #monsoon #tropicalstormmario
September 17, 2025 at 8:02 PM
Flood Watch issued for a good chunk of SoCal. #floodwatch #cawx #flooding #monsoon #tropicalstormmario
Reposted by Diana Leonard
Today's 12z Model runs having different ideas as to which locations will be in the "bullseye" for rainfall in #SoCal. Ventura, Santa Barbara and San Luis Obispo Counties are favored. With this type of system, heavy Thunderstorms could occur pretty much anywhere while other locations miss out. #CAwx
September 17, 2025 at 6:11 PM
Reposted by Diana Leonard
Morning view on lightning detection / satellite shows activity near the Central Coast. Should have chances in increasing regionwide later today and into Friday 9/17/2025 #CAwx
September 17, 2025 at 3:09 PM
Morning view on lightning detection / satellite shows activity near the Central Coast. Should have chances in increasing regionwide later today and into Friday 9/17/2025 #CAwx
Reposted by Diana Leonard
No, Mount St. Helens is not erupting. After a long, hot, and dry summer, strong southeast winds are stirring up loose ash from the 1980 eruption! Here's the view from a DNR Pano cam. Not something you see every day... #wawx
September 16, 2025 at 6:24 PM
No, Mount St. Helens is not erupting. After a long, hot, and dry summer, strong southeast winds are stirring up loose ash from the 1980 eruption! Here's the view from a DNR Pano cam. Not something you see every day... #wawx
Reposted by Diana Leonard
I’m proud to say that @noaa.gov and NCEI has released a 1 year retrospective on #Helene using ESRI Story Maps.
arcg.is/aqCD4
Here is a brief thread of how this came to be and how NOAA can still do good things (even while wearing pajamas).
arcg.is/aqCD4
Here is a brief thread of how this came to be and how NOAA can still do good things (even while wearing pajamas).
Helene in Southern Appalachia
One year later: An event analysis and how we move forward.
arcg.is
September 16, 2025 at 4:25 PM
I’m proud to say that @noaa.gov and NCEI has released a 1 year retrospective on #Helene using ESRI Story Maps.
arcg.is/aqCD4
Here is a brief thread of how this came to be and how NOAA can still do good things (even while wearing pajamas).
arcg.is/aqCD4
Here is a brief thread of how this came to be and how NOAA can still do good things (even while wearing pajamas).