weather, weather safety/preparedness

More Naples, FL area wildfires (H. Michael Mogil, CCM, CBM, NWA-DS*)

Late Thursday, Apr. 20, 2017, two wildfires of unknown origin broke out in the Golden Gate Estates area of east Naples, FL. Although fire fighters jumped into action quickly, dry and windy conditions allowed the fire to spread. By this morning, the combined blazes had grown to about 2,500 acres.

Collier County Emergency Management issued evacuation orders for some limited areas yesterday and expanded areas affected during today. As of late this afternoon, the boundaries of the evacuation area extended from the south side of Golden Gate Boulevard south to the east-west portion of I-75 and from Collier Boulevard east to Wilson Boulevard.

Jim Dickey, WZVN-TV (CH 7 – ABC, Fort Myers) Certified Broadcast Meteorologist, posted radar imagery at around 10:00 a.m. E.D.T. today of the dual fires at his Twitter page (@WxDockey). Dickey noted that “Now that A.M. inversion has lifted, smoke plumes from #30thStFire and #FrangipaniFire visible on radar” (Fig. 1).

     Images from the Immokalee Fire Control District showed the scope of the fires and their associated large billowing smoke clouds (Fig.2 and Fig. 3). Overnight and during Friday morning, the smoke reached the Naples City limits, lowering visibility at the Naples Airport (KAPF) to 3 miles. Based on the trajectory of the plume this morning (WZVN-TV radar imagery and video), and the fact that the smoke plume is still showing up on the Miami National Weather Service radar late this afternoon, most of western Collier County (including the city of Naples) and parts of southern Lee County are going to be experiencing smoky conditions through tonight and into early Saturday morning.

Thus, smoke from the fire will be affecting many more people than the fire itself. Small airborne particles from the fire may lead to respiratory problems, even for healthy people. Check out Fig. 4, a wildfire poster from http://www.ready.gov, republished by Florida Health. It contains some useful tips for dealing with smoky air.

© 2017 H. Michael Mogil

Originally posted 4/21/17

* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.

weather, weather safety/preparedness

The winds win! (H. Michael Mogil, CCM, CBM, NWA-DS*)

Today through tomorrow evening, large areas of the Nation and some nearby ocean water areas are under various types of wind warnings. From hurricane-force wind warnings in New England’s offshore waters (large-scale winter storm and intense pressure gradient) to Santa Ana (canyon-channeled) winds in southern California (Fig. 1), the winds win!

In New England, for added measure, heavy snow and bitter cold will add to the misery. Across parts of west Texas, a wintry mix will develop. In the mid-Atlantic, it’s a combination of large-scale vertical mixing (high speed winds from higher altitudes mixed down to the ground) and the effects of downslope winds.

In all of these land areas, winds will be high enough to affect the travel of high-profile vehicles and even passenger cars. Offshore from New England, waves will build to heights of more than 30 feet. As noted in National Weather Service marine warnings, “seas are given as significant wave height…which is the average height of the highest 1/3 of the waves. Individual waves may be more than twice the significant wave height.” Hence, if a 60-foot wave does form, it would take on the scope of the self-proclaimed “George Clooney Memorial Wave” in “The Perfect Storm” movie.

Winds will die down in many locales by Tuesday, as a more tranquil weather pattern establishes itself. Until then, drive safely, act cautiously, and stay in safe places.

© 2017 H. Michael Mogil

Originally posted 2/12/17

* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.

weather, weather safety/preparedness

One New England Blizzard…Two New England Blizzards… (H. Michael Mogil, CCM, CBM, NWA-DS*)

On Feb. 9, 2017, southeastern New England experienced a significant snowstorm. Within the storm’s circulation, blizzard conditions lasted for some three to almost six hours and affected many areas. The National Weather Service (NWS) Office in Taunton, MA summarized the storm in a lengthy weather release on the evening of Feb. 9, 2017. Excerpts from that release have been provided here (all times Eastern Standard Time).

The storm responsible for the blizzard (Fig. 1 – left) was a “meteorological bomb,” a storm that undergoes rapid pressure falls (or “explosive deepening”) of at least 24 millibars (0.71 inches of mercury) in 24 hours. Bombs typically contain some “thundersnow,” which often means locally heavier snowfall. This bomb was no exception.

First, it’s important to reiterate what a blizzard actually is. According to the NWS, a blizzard involves falling and/or blowing snow, sustained or frequent wind gusts of 35 miles per hour or more and visibilities frequently reduced to less than a quarter of a mile. All of these conditions must last for three hours or more.

For purposes of this summary, the NWS meteorologists used only official airport reporting stations (since all of the above weather conditions are routinely reported at these). For visibilities, they decided to use reported values of one-quarter mile or less since, “…that is quite low for an automated sensor to detect.” Obviously, blizzard conditions occurred elsewhere across the area.

  • Providence, RI wins the competition with 5 hours and 18 minutes of blizzard conditions (10:51 a.m. to 4:09 p.m.).
  • Hyannis, MA was a close second with 5 hours and 4 minutes (12:56 p.m. to 6:00 p.m.).
  • Boston, MA netted blizzard conditions for 4 hours and 34 minutes (12:20 p.m. to 4:54 p.m.).

Other locations reporting blizzard conditions (in decreasing length of time of blizzard conditions) included Martha’s Vineyard, MA; Block Island, RI; Beverly, MA; Marshfield, MA; New Bedford, MA; and Westerly, RI.

As the region digs out, another storm system looms on the western horizon. This one, much like its predecessor, promises to involve “explosive deepening” as it passes by the region from late Sunday into late Monday (Fig. 1 – right). However, its movement will be significantly slower, allowing heavy snowfall and blizzard conditions to last longer. Already, local snowfall forecasts are pegged at approaching two feet.

This will be a “hunker down” storm. So stay home, dress in layers if you venture out, and, unless you have a snowblower, consider letting a local teenager shovel your driveway.

© 2017 H. Michael Mogil

Originally posted 2/11/17

* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.

weather, weather safety/preparedness

Long duration lake-effect snow event underway (H. Michael Mogil, CCM, CBM, NWA-DS*)

The National Weather Service has issued “lake effect” snow warnings and advisories for areas to the east of Lakes Erie and Ontario through Sunday evening (Fig. 1). These forecasts call for locally heavy snow and wind-blown snow with associated hazardous driving conditions. Forecasts for areas in New York State downwind of these lakes indicate that snowfall amounts will be within a 15 and 40 inch range (locally higher amounts expected) along with wind gusts to 45 miles per hour. The heaviest snowfalls are expected in the Tug Hill Plateau area (downwind from Lake Ontario, near Watertown and Montague, NY), with 12-hour snowfalls, throughout the period, frequently in the six to 12 inch range. Already, early this Friday morning, Watertown reported wind gusts in excess of 40 miles per hour.

While not yet issued, look for similar forecasts to be posted for other downwind areas of the entire Great Lakes region during the next several days.

This entire weather scenario is linked to a quasi-stationary surface and upper air low-pressure system across eastern Canada (Fig. 2). The system’s counter-

clockwise circulation will send winds across the Great Lakes, mostly from a west to northwest direction.

With the Great Lakes mostly ice free (Fig. 3), colder air, moving over relatively warmer water, can gain heat and moisture. This allows clouds (often low-topped) to develop in bands across the lakes (Fig. 4). As these bands make landfall, the air they are riding on experiences increased frictional drag

(friction is higher as winds blow over land than water). The result is a low-level convergence effect, adding uplift to the clouds. In areas where terrain increases inland, there is an added orography-lift effect (e.g., the Tug Hill Plateau area). In a snowfall event earlier this winter season, parts of the Tug Hill Plateau were targeted with over four feet of snow in a three-day period.

Due to the nature of “lake effect” snow events, the National Weather Service in Buffalo, NY noted early this Friday morning that, “…in lake effect snow, the weather can vary from locally heavy snow in narrow bands to clear skies just a few miles away. If you will be traveling across the region, be prepared for rapid changes in road and visibility conditions.”

© 2017 H. Michael Mogil

Originally posted 1/27/17

* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.

weather, weather safety/preparedness

Enhanced severe weather threat for southeast U.S. (H. Michael Mogil, CCM, CBM, NWA-DS*)

Batten down the hatches (and be prepared to take shelter today and tonight) if you live or are traveling across the southeast U.S. The Storm Prediction has issued a highly unusual severe weather outlook for the region – calling for a moderate to high severe weather risk for South Carolina, Georgia, a small part of southeast Alabama and much of northern and

central Florida (Fig. 1). According to news reports, the storm system behind today’s severe weather threat has already claimed the lives of at least six people across Mississippi and Georgia.

Fig. 2 and Fig. 3 show the radar and satellite images, respectively, late this Sunday morning. What is most telling is that the current strong thunderstorm activity is occurring in a region of dry air aloft (the oranges and blacks on the water vapor satellite image – Fig. 3). This means that rising air

inside the thunderstorms must be moving at very high velocity to counter this dryness. Hence, many of the stronger thunderstorms are already likely acting as “supercells (isolated storms ahead of a line of storms).” Two apparent supercells can be seen in the northern Gulf of Mexico (Fig. 2).

As a new low-pressure system develops across the southeast today, and moves to northern Georgia and eastern Tennessee by tonight,

(Fig. 4), a very strong jet stream aloft (winds greater than 130 miles per hour) and a very warm and unstable air mass (dew points above 70 degrees F) will all be factoring into the storm evolution as the day and night progress.

The local storm potential graphic (Fig. 5) indicates just how strong the storms may be, even removed from the main threat region.

As the newly forming low develops, it will move to the northeast and spread a large shield of rain along the entire east coast during the next several days. Except for parts of New England, the atmosphere is just too warm for snow.

Although winds will be strong across the southeast today, coastal wave action, higher than average tides,

rip current danger and other coastal and boating dangers (including offshore gale warnings in the Gulf of Mexico) will be the watchwords across the west coast of the Florida peninsula into the Gulf beginning tonight and continuing until Tuesday (Fig. 6). That is because strong west and northwest winds will arrive once the cold front clears the area (Fig. 4).

Although skies may be sunny to partly cloudy across much of the Florida peninsula now, conditions will rapidly deteriorate during the latter part of the calendar day and early Monday morning.

Stay tuned to the National Weather Service, local broadcast media outlets and any tailored private weather subscriptions you may have for watches, warnings and advisories.

If you have loose objects outdoors, consider bringing these inside before the storms arrive.

© 2017 H. Michael Mogil

Originally posted 1/22/17

* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.

weather, weather safety/preparedness

Ground fog! (H. Michael Mogil, CCM, CBM, NWA-DS*)

Dense fog advisories (Fig. 1) as well as the fog they describe (Fig. 2), covered southwest Florida early this Friday morning (Jan. 6, 2017). Some places had 0-0 visibility (that is, zero feet both horizontally and vertically); other places had visibilities of several miles horizontally and several hundreds of feet vertically (Fig. 3). Visibility is defined as how far one can see cloud bases (vertically) or known ground-based objects (horizontally).

   

It is the variation in fog thickness horizontally (and associated visibility) that came to the forefront this morning as I walked my dog, Pepper, around our southwest Florida neighborhood.

  

First, looking up my street, visibility was about a half mile, the measured length of my street (Fig. 4). As soon as Pepper and I walked onto the golf course, fog density increased and visibility decreased (Fig. 5). As we approached the location of my COCORAHS (Community Collaborative Rain Hail and Snow Network) rain gage, which is adjacent to a large pond, the fog density increased further and visibility tumbled down to a few hundred feet (Fig. 6). All images were taken within 10 minutes of one another.

These three scenarios are described in the table below:

Location Fog density Visibility
Street light ½ mile
Golf course dense ~ ¼ mile
Near pond very dense few hundred feet

For the street, warmer air temperatures resulted in less dense fog. Over the golf course, temperatures were slightly cooler, allowing for somewhat dense fog to develop. In the pond area, cooler air temperatures and higher atmospheric moisture contributed to the densest fog.

Note that these conditions contribute to the formation of fog. But, local winds, drainage winds, and other factors can allow fog areas to move. Not surprisingly, this can result in highly variable fog density along roadways. Common sense dictates that motorists of all types of vehicles (cars, buses, trucks) drive more slowly and pay even greater than average attention to potentially rapidly changing visibility.

While the dense fog has lifted already, it will be back again, especially during the upcoming winter months.

– – – – –

© 2017 H. Michael Mogil

Originally posted 1/6/17

* The National Weather Association Digital Seal (NWA-DS) is awarded to individuals who pass stringent meteorological testing and evaluation of written weather content. H. Michael Mogil was awarded the second such seal and is a strong advocate for its use by weather bloggers.

 

weather, weather safety/preparedness

Chilly wind chills for south Florida (H. Michael Mogil, CCM, CBM, DMS)

Once a strong Pacific cold front barrels through south Florida later today, attention will shift to windier weather and much chiller temperatures. The combined effect of wind and temperature will contribute to unusually low wind chills for the area. Wind chill is a measure of heat loss from exposed skin.

For Friday morning, wind chills across south Florida will range from the mid 40’s in more northern inland locales to the lower 60’s along southeast and southern locations (Fig. 1).  By Saturday morning, wind chills from Collier County northward, along the west coast, will likely dip into the 30’s and lower 40’s. The combined effect of nearby warm Atlantic waters and a northerly wind flow across Lake Okeechobee (whose waters are still quite warm) will keep East Coast southeast inland locations mostly in the mid 40’s to near 60 degrees (Fig. 2).

Then the chill vanishes, almost as quickly as it came.  Winds will quickly turn to east and allow warmer, more humid air from over the Atlantic to move back into the area. Hence, by Saturday afternoon, many western areas of southwest Florida will see temperatures skyrocket into the mid 70’s.

As noted in yesterday’s post, for the fireworks and other outdoors activities on New Year’s Eve, look for temperatures across southwest Florida to fall back into the mid to upper 60’s with light (5 to 10 mile per hour) southeasterly winds.

© 2016 H. Michael Mogil

Originally posted 12/29/16

weather, weather safety/preparedness

Matthew heading for Florida… (H. Michael Mogil, CCM, CBM, DMS)

There’s an old expression about, “proximity.” It goes, “close, but no cigars.” That was clearly contrived in another era. However, in the case of Matthew, close may be close enough.

fig001-matthew-nhc-track-fcst-map-161005-8amedtThe latest National Hurricane Center’s (NHC) projected track for Matthew brings him very close to the Florida east coast near Jupiter Beach, FL by early Friday (Fig. 1). Given the size of the tropical force wind zone (sustained winds up to and including 73 miles per hour), which has been focused to within about 45 miles from the storm’s eye (with tropical storm force winds extending outward some 175 miles outward from the eye), many places in Florida will be very windy on Thursday and Friday. Locations closest to the east coast of Florida will be at the highest risk of hurricane force winds; many inland locales will experience tropical storm force winds.

fig002-sfl-watch-warning-map-161005-8amedtAs a result of Matthew’s closer approach to the east coast of Florida, hurricane and tropical storm watches and warnings have been posted for much of southern and eastern Florida (Fig. 2).

Don’t be misled by some TV meteorologists and news folks who prefer to focus on wind gusts. Wind gusts are not the measure of tropical storm or hurricane wind force conditions. They may be good for inciting excitement that the storm is stronger than it is, but…

The entire suite of hurricane dangers can be expected along the east coast of Florida. This includes high winds, torrential rains, coastal wave action, storm surge, beach erosion, local flooding and even a risk (albeit low) of tornadoes. Inland locations of south Florida, as far west as the north-south I75 corridor, can expect high winds. There will likely be a very significant rainfall gradient between coastal and inland locales, with the heaviest rainfall closer to the coast.

West coast Florida coastal areas can expect some rough surf and beach erosion.

Obviously, winds and waves over nearshore and offshore areas and Lake Okeechobee will make any water-based activities extremely dangerous.

In addition to state-declared states of emergency from Florida northward to the Carolinas, airlines have begun implementation of no-charge rebooking programs, especially for flights departing from east coast Florida airports. Note that some airlines will charge the current price of a ticket, not the price paid months ago (please read the fine print to be sure).

Florida Power and Light (FP & L), the state’s major energy supplier, has sent e-mail notices to its business customers advising them that FP &L was ready for the storm. No doubt, supermarket shelves will soon be stripped of toilet paper, milk, eggs, break and water. Hardware store will soon have no plywood for sale. And gas station lines have been reported as being long.

A safe rule, espoused by emergency management agencies, especially for hurricane warning areas, is to have a 3-day supply of water and non-refrigerated food on hand.

In some places along the southeast coast (particularly South Carolina) coastal evacuations are being ordered. This includes the state’s lane reversal evacuation plan to lessen gridlock. Under the plan, Interstate 26 will only allow traffic flow away from the coast. In other places, county evacuations are being urged, especially for low-lying coastal areas and/or sand bags are being provided by local government agencies.

As I have noted for the past several days, tropical cyclone forecast position errors grow with time. NHC has willingly shared its error values: around 175 miles at day 4 (96 hour forecast) and 230 miles at day 5 (120 hours forecast). Hence, Matthew could wind up being positioned anywhere within or near the “cone of uncertainty.”

With a storm, roughly paralleling the coast, even a slight shift is track can produce significant changes to expected weather and water conditions. One has only to think back to Hurricane Charley in 2004. For that event, a slight jog toward Florida’s west coast yielded a landfall just north of Fort Myers, rather the expected landfall 150-200 miles further north, near Tampa.

fig003-4-5-matthew-modle-forecasts-valid-161011-00z-8amedtLooking well into the future, where forecast errors continue to grow, Matthew has transitioned from a New England/eastern Canada landfall to one in which the storm was expected to race across the north Atlantic toward western Europe to the current scenario in which Matthew stays roughly in place off the southeast coast and returns to the Miami area later next week. This is all the result of changes in upper level wind forecasts (because upper level winds steer hurricanes). Figures 3 through 5 showcase a few of these long-range solutions (all valid for the same time – 8:00 a.m. E.D.T. on Oct. 11, 2016).

With this long-term solution scatter in mind, it’s best to key on the first five days of the forecast. Get ready if you are in a watch or warning area and stay tuned to reliable weather updates through the period of risk.

© 2016 H. Michael Mogil

Originally posted 10/5/16

weather, weather safety/preparedness

Newton weakens; brings flash flood threat to parts of Arizona and New Mexico… (H. Michael Mogil, CCM, CBM, DMS)

Fig001-Newton-storm-track-160907-1500ZAs quickly as Newton formed, it has begun its demise. Moving across rough terrain in northwestern Mexico, Newton has been downgraded to tropical storm status early this Wednesday morning. By this evening, according to National Hurricane Center forecasters, Newton should be in depression status as it moves across southeastern Arizona (Fig. 1).

Fig002-radar-map-160907-1428Z    Fig003-watch-warning-map-early-on-160907Already, Newton has spread tropical moisture northward into Arizona and New Mexico (Fig. 2). With some reports of one to two inches of precipitation already and widespread general rainfall occurring already across southern parts of the two states, flash flood watches have been posted until this evening (Fig. 3). In parts of Maricopa County (west of Tucson), a flood advisory has been posted. According to the Tucson National Weather Service (NWS) office, “as of 6:57 a.m. M.S.T…gauge reports indicated one to 1.5 inches of rain (had fallen) over the past one to two hours…” The rain was linked to a line of heavy showers and thunderstorms moving into the area from the east (within the counter-clockwise circulation of Newton).

With rainfall amounts possibly reaching four inches or more locally, several NWS offices across the flash flood watch area have advised that normally dry arroyos (dry stream beds) will likely see rising water as the day progresses. And with the rainfall expected to continue all day, as is always the case with arroyos and low water roadway crossings in dry wash areas, the NWS has urged drivers to be especially cautious and not drive into any flooded areas or any areas with moving water. Conditions will be more treacherous in mountainous areas (due to merging runoff from small watershed areas) and downstream from any burn scar areas (linked to recent forest or grassland fires). Scar areas are often more impervious and lack vegetation that can lessen flooding dangers.

Once Newton moves through the area overnight, only slight chances of shower and thunderstorm activity are expected for the remainder of the week.

© 2016 H. Michael Mogil

Originally posted 9/7/16

weather, weather safety/preparedness

Tropical Storm Hermine is now getting weird (H. Michael Mogil, CCM, CBM, DMS)

Fig001-NHC-Hermine-track-fcst-from-160903-5amEDTTake a look at today’s early morning (Sept. 3, 2016) Hermine forecast track from the National Hurricane Center – NHC (Fig. 1) and you’ll see several things appear to be, well, just plain weird. However, there is some good rationale behind each of these.

First, Hermine is expected to slow down and possibly try to make a cyclonic (counterclockwise in the Northern Hemisphere) loop off the New Jersey coast early next week. This is linked to Hermine’s interaction with a developing, middle latitude, cold core, cut-off upper level low-pressure system.

Next, the 72-hour forecast indicates that Hermine will transition into a middle-latitude or extra-tropical hurricane. This, too, is linked to interactions between the upper low and Hermine. It is also tied to Hermine exiting the Carolina’s and moving back over relatively warm waters. The storm will become a hybrid with some attributes of a hurricane (wind speed core near the storm’s center) and some associated with a winter-like storm (colder central core temperatures).

Due to proximity to land, and with lessons learned from Storm Sandy in 2012, NHC will continue to issue advisories on Hermine, even after the storm becomes extra-tropical. This is to better keep public attention on hurricane dangers.

Finally, hurricanes do not usually slow down and spin within a relatively confined geographical area, once they recurve to the northeast. However, the “Perfect Storm” (a.k.a., the Halloween Storm of 1991) and Storm Sandy in 2012 (see synoptic maps animation) are among storms that have undergone a similar type of tropical/middle-latitude interaction in which a middle-latitude, upper level low “captures” the hurricane circulation.

Hermine is not done wreaking her havoc on the U.S. East Coast. She has already produced a significant storm surge and associated coastal erosion in Florida’s Big Bend region – mainly Taylor County (thanks to the storm’s track and the shape of the coastline immediately to the southeast of the storm’s path); excessive rainfall along Florida’s west coast, including nearly 20 inches in the Tampa area (Pinellas County); and widespread wind damage to homes, trees and power lines (with significant power outages – in the hundreds of thousands).

Fig002-Atlantic-City-5-day-fcst-TS-conditions-160903Early Saturday morning, tropical storm watches and warnings, storm surge alerts, forecasts of additional excessive rainfall and tornado watches cover at least parts of coastal locales from the Carolinas into southern New England. However, the best measure of the overall, long-term, potential impacts is the five-day graphic forecast for Atlantic City, New Jersey (Fig. 2). Tropical storm conditions (including pounding surf and storm surge) will likely cause serious coastal damage and erosion.

© 2016 H. Michael Mogil

Originally posted 9/3/16