November 2024 Skyview Weather Monthly Newsletter

Feature Article

Understanding Hurricane Categories: How Hurricanes Like Milton and Helene are Classified

As Coloradans, we’re no strangers to nature’s power – from blizzards to wildfires, our weather has its own intensity. However, the recent hurricanes Milton and Helene have raised questions about how hurricanes are categorized, particularly as some of these storms reach destructive intensities. Hurricanes are categorized using the Saffir-Simpson Hurricane Wind Scale, which measures sustained wind speed and estimates potential damage, assigning each hurricane a rating from Category 1 to Category 5. This scale helps gauge the potential impact of storms, ranging from minor damage to catastrophic destruction.

Saffir-Simpson Hurricane Wind Scale

This scale categorizes hurricanes based on sustained wind speeds, recorded using a U.S. 1-minute average. Each category signifies an increase in destructive power, with storms rated Category 3 and above classified as major hurricanes due to their capacity for extensive damage and loss of life. However, even lower categories require caution and preventative measures to ensure safety.

Category 1 Hurricane

Winds: 74-95 mph (119-153 km/h)
Damage: Though the lowest category, Category 1 hurricanes bring “very dangerous winds.” These storms can cause damage to roofs, shingles, and gutters of well-constructed homes, while large tree branches may snap, and shallow-rooted trees could be toppled. Power lines and poles can also be damaged, resulting in outages lasting several days.

Category 2 Hurricane

Winds: 96-110 mph (154-177 km/h)
Damage: Category 2 hurricanes bring “extremely dangerous winds,” often causing major roof and siding damage to well-built homes. Many shallow-rooted trees are likely to be uprooted, blocking roads and potentially delaying emergency responses. Power outages can last several days to weeks in impacted areas.

Category 3 Hurricane

Winds: 111-129 mph (178-208 km/h)
Damage: The increase in wind speed at Category 3 is significant. “Devastating damage” occurs in these storms, as roofs and gable ends of homes can be torn off. Trees are more extensively snapped or uprooted, and power and water may be unavailable for days to weeks after the storm has passed.

Category 4 Hurricane

Winds: 130-156 mph (209-251 km/h)
Damage: In a Category 4 hurricane, well-built homes can suffer severe structural damage, including the loss of much of the roof or even some exterior walls. Trees and power poles are generally snapped or toppled, leaving large residential areas isolated and without power. Infrastructure damage could take weeks or months to repair, and recovery can be especially challenging.

Category 5 Hurricane

Winds: 157 mph or higher (252 km/h or more)
Damage: A Category 5 hurricane delivers the peak of the scale’s destructive potential. “Catastrophic damage” can be expected, with most framed homes experiencing complete roof failure and potential wall collapse. Areas affected may be uninhabitable for weeks or even months due to severe power, infrastructure, and water outages. Notable Category 5 hurricanes like Hurricane Andrew in 1992 serve as reminders of the extreme destruction these storms can bring.

Hurricanes Milton and Helene: Learning From Major Storms

Though hurricanes rarely impact Colorado directly, the sheer magnitude of recent storms like Milton and Helene captures our attention. Understanding the classification system helps us to comprehend the preparations and cautionary steps coastal areas must take when such storms approach. It also serves as a reminder of the resilience communities need to adapt and recover from these natural events.

As we watch these hurricanes develop, the Saffir-Simpson Scale provides insight into how much preparation is required based on wind speed alone. While these storms may not touch our state, they remind us of the value of preparedness, whether facing a blizzard, wildfire, or a storm from afar.

 

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Colorado Drought Update

 

A brutally dry September and October for north-central Colorado has sent those regions into extreme drought, covering much of Boulder and Larimer counties. An active monsoon season in the southwest portion of the state has kept most of that region in good condition, but generally, drought intensifies as one travels northeast throughout the state. Given that our most recent storm produced much-needed water across portions of the state that are under drought status, we should see improvement in this map next month.

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November 2024 Temperature Anomaly Forecast

The Climate Prediction Center (CPC) has issued an outlook that indicates November will be very different from October this year in Colorado. After the warmest October on record, it appears likely that November will be much closer to average for fall in Colorado, as well as much of the western US. As one travels further east, it gets more and more likely that this November will be a bit warmer than normal. Louisiana to New England will likely see a month dominated by more warm ridge patterns in the upper atmosphere.

November 2024 Precipitation Anomaly Forecast

Much of the US is likely to see normal levels of precipitation this month, including most of the Rockies and all of the Appalachian chain of mountain ranges. The Midwest appears like it’ll have a good November for preceipitation, which corresponds also with the region where air masses collide in the temperature maps above. With average air on one side and warm air on the other, active weather can be expected across the Midwest. It also is likely to be active on the eastern slopes of the Cascades in the Pacific Northwest.

Weather Summary for Colorado, October 2024

While it looked likely that Colorado would have a warm October, not even the smartest meteorologists expected Denver to turn into Phoenix for 31 days. 2024 officially recorded the second warmest October in Denver’s history (behind 1950), with an average temperature of 59.1°F coming in at a whopping 8°F above normal. While no days officially hit 90° at the official record site at DIA, multiple temperatures records were set, especially during the warmest stretch in the beginning of the month.

Denver typically sees its first snowfall in October, but not in 2024. In fact, very little precipitation fell throughout the month, with only 0.11” reported at DIA. Normally, around an inch of rain or snow falls throughout October over 6 days. This year, that 0.11” fell in just 2 days. If pictures could talk, this one would tell you all that you need to know about what Colorado felt like through October. Statewide, it was hot, hot, hot.

Weather Statistics for Denver International Airport (DIA), October 2024

DIA Temperature (°F), October 2024

TEMPERATURE (IN DEGREES F)	OBSERVED VALUE	NORMAL VALUE	DEPARTURE FROM NORMAL
AVERAGE MAX	75.1°F	65.3°F	9.8°F
AVERAGE MIN	43.2°F	37.0°F	6.2°F
MONTHLY MEAN	59.1°F	51.1°F	8.0°F
DAYS WITH MAX 90 OR ABOVE	0	0.8	0.2
DAYS WITH MAX 32 OR BELOW	0	0.0	0.0
DAYS WITH MIN 32 OR BELOW	4	9.2	-5.2
DAYS WITH MIN 0 OR BELOW	0	0.0	0.0

DIA Liquid Precipitation (Inches), October 2024

PRECIPITATION (IN INCHES)
MONTHLY TOTAL	0.11”		0.99”	-0.88
YEARLY TOTAL	11.74”		8.42”	3.32”
GREATEST IN 24 HOURS	0.09”	10/18
DAYS WITH MEASURABLE PRECIP.	2		5.3	-3.3

2024 Snowfall Accumulation for the Colorado Eastern Plains

City	Oct	Nov	Dec	Jan	Feb	Mar	Apr	Total
Aurora	0							0
Boulder	0							0
Brighton	0							0
Broomfield	0							0
Castle Rock	0.2							0.2
Colorado Springs Airport	0							0
Denver DIA	0							0
Denver Downtown	0							0
Golden	0.6							0.6
Fort Collins	0.2							0.2
Highlands Ranch	0							0
Lakewood	0							0
Littleton	0							0
Monument	2							2
Parker	0							0
Sedalia – Hwy 67	0							0
Thornton	0							0
Westminster	0							0
Wheat Ridge	0							0
Windsor	0							0

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November 2024 Preview

Well, this November edition of the Skyview Newsletter got derailed by an obvious factor: The second-largest November snowstorm in Denver’s recorded history. While there was a signal of a storm at the calendar changed from October to November, the nature of this system was not anticipated. This past system slowly dropped down from the Pacific Northwest, spun over the desert southwest and Four Corners for a while, then migrated its way through New Mexico before swinging almost directly north along the Colorado/Kansas border, leaving behind feet of snow for much of the Front Range of Colorado.

Current indications are of relatively normal temperatures for the rest of this week, followed by the arrival of a cool but mostly dry system early next week. After that system, it will likely be above average in temperature for a bit, as the system next week is appearing to stall out a bit over southern Appalachia. Following what is a typical 6-9 day transition season weather pattern, the next system should arrive in the middle of the final week of the month, potentially bringing some cold air and the chance for snow.

November Climatology for Denver

(Normal Period 1991-2020 Dia Data)