astronomy, weather

The Moon and Venus are getting closer (H. Michael Mogil, CCM, CBM, DMS)

If you happened to look to the west-southwest tonight just after sunset, and the clouds didn’t get in the way, you got to see the Moon catching up to Venus. Venus is the brightest planet in the sky right now and continues to impress in the evening sky.

The other night, a faint waxing crescent moon appeared on the western horizon just after the sun set. During the past two nights, as the sky darkened, the moon has become more easily visible in a position higher in the sky. Tonight, it lies just beneath Venus.

Mars, a very faint, reddish, planet by Venus’ standards, sits well above and slightly to the left of Venus.

All of these celestial bodies are annotated in Fig. 1 (image taken in Naples, FL).

Tomorrow evening, according to Earth & Sky, the Moon will sit above Venus, but below Mars.

Hope the clouds don’t ruin an impressive New Year’s sky show for my readers.

Enjoy!

© 2017 H. Michael Mogil

Originally posted 1/1/17

weather

What a difference a wind direction makes (H. Michael Mogil, CCM, CBM, DMS)

The other day, I wrote about the arrival of a strong cold front in south Florida. That front arrived with a significant chill down. Low temperature readings, this Saturday morning (Dec. 31, 2016), were in the 40’s across many areas of southwest Florida. Even with relatively light north winds, wind chill readings dipped into the 30’s to the north of a Fort Myers-Lake Okeechobee line. Dew point readings tumbled into the teens and twenties in many areas (Fig. 1).

But, with brilliant sunshine and a wind shift to the southeast, temperatures soared into the 70’s across most of south Florida by mid-day Saturday (Fig. 2) and into the mid- to upper- 70’s across southwest Florida by Saturday afternoon. Of even more significance was that dew point readings jumped from the 20’s into the low and mid 50’s in most places (Naples shown in Fig. 3).

This transition was linked to a change in wind direction. During the day on Friday and into Saturday morning, winds arrived from the north and northeast (Fig. 1); this kept the trajectory of the arriving continental Polar air mass passing over land. On Saturday, the trajectory of air was from water first and over the Florida peninsula next (Fig. 2). The result was that a continental Polar air mass had been replaced quickly by a maritime Tropical one.

And the trend will continue. By today, New Year’s Day, highs across southwest Florida reached the low- to mid- 80’s. Morning lows only dipped into the mid 60’s to lower 70’s along the southeast coast and low 60’s in most other coastal locations. These warmer day- and night- time readings should be the rule (plus or minus a few degrees) for most of the upcoming week.

I hope to be writing, soon, about examples in which wind direction and/or variations in wind direction play a significant role in an evolving weather event. Other GWCC writers have already posted regarding lake effect snow showers and squalls. Stay tuned!

© 2017 H. Michael Mogil

Originally posted 1/1/17

climate, weather

View from the top of the world (H. Michael Mogil, CCM, CBM, DMS)

Santa has been in the news of late. So, I thought it might be fun to take a look at weather from Santa’s perspective. To do this, we’ll have to look at upper level and surface weather maps from a polar-centric perspective. Fortunately, NOAA’s National Center for Environmental Prediction (NCEP) produces forecast weather maps for many regions of the globe, including maps centered on the geographic North Pole.

I decided to use NCEP forecast upper level (Fig. 1) and surface (Fig. 2) maps for Jan. 7, 2017 (eight days into the future) just because the patterns on these maps would be the easiest to explain. There are three important observations that I’d like to share.

First, the jet stream (a long, thin ribbon of high altitude, high speed moving air), shown by shades of blue, extends in a more-or-less continuous band around the globe. However,

there are times when the jet stream exhibits a more broken pattern. In general, the jet stream separates colder air on its polar side from warmer air on its Equatorward side.

Second, the jet stream exhibits dips (troughs or low-pressure areas – shown by orange lines in Fig. 1) toward the Equator and bulges (ridges or high-pressure areas) toward the pole. Associated with these upper level features are matching surface features (typically displaced slightly to the east of their upper level counterpart). Most of the upper level troughiness and most of the surface low-pressure systems lie within the 45 to 60 degree North latitude band. This is slightly south of the climatologically-preferred latitude.

Third, the “polar vortex” is not a single upper level low-pressure system, but rather a large zone (covering much of the high latitude region) with many low-pressure systems within it. These low-pressure systems rotate in a counterclockwise sense (west to east) around the overall “vortex” center. Here, one larger lobe of the “vortex” covers much of Canada.

The troughs noted under item two above actually appear like spokes on a wheel, as they, too, rotate around the main polar vortex circulation center.

Given this “polar vortex” and jet stream pattern, northern states will continue to be ruled by cold air, while southern states will enjoy well-above average temperature readings. In between, warm and cold air will battle for control, with a much more changeable weather pattern.

NCEP’s eight- to fourteen-day forecast (Fig. 3) shows this overall pattern. The only exception is that below average readings should trend further southward thanks to more troughiness in the west, an expected slight jet stream dip southward, and the further southward displacement of cold surface air.

Finally, the storm track suggests that the Northeast will be the recipient of the most stormy weather action. Based on details of longer range model forecasts (not shown), more meteorological “bombs” (very rapid low-pressure deepening) are coming.

© 2016 H. Michael Mogil

Originally posted 12/30/16

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

climate, weather

Record Precipitation for Minneapolis, MN in 2016 (H. Michael Mogil, CCM, CBM, DMS)

Throughout 2016, we heard a lot about California’s long-term drought and a short-term, evolving, drought across the southeast U.S. There were also a few heavy rainfall events. Now, as we approach year’s end, annual precipitation (and other weather) records are going to be making the news.

One of the first to cross my desk was from the National Weather Service (NWS) Minneapolis office. Through yesterday, a yearly record 40.32 inches of precipitation had fallen at the Minneapolis (MSP) airport (Fig. 1). This eclipsed a record last set 105 years ago. With weather records dating back to 1871, this takes on even greater weather significance.

Some may ask, “how can weather records at an airport date back to before we had aviation and airports?” This is a very good question with a very easy answer. Due to many factors, including urbanization, observing site relocation, and others, observing sites for most places have undergone some to many relocations during their lifetimes. Each NWS office keeps track of these. The focus is on keeping the weather record as uniformly-obtained as possible.

With that part of history behind us, let’s turn to the precipitation records themselves. Here are the top 5 annual numbers (although 2016 may change a little during the next few days):

2016 – 40.32”

1911 – 40.15”

1965 – 39.94”

1983 – 39.07”

1881 – 39.06”

Note that these totals are NOT for rainfall, but rather precipitation. Snowfall (and possibly sleet and/or hail) is transformed into liquid water content (i.e., melted) and then that water is counted in precipitation totals.

By-the-by, the 30-year precipitation average for MSP is 30.61”. So this year’s precipitation is nearly 32 percent above average!

© 2016 H. Michael Mogil

Originally posted 12/29/16

weather

Record Florida warmth comes to an end (H. Michael Mogil, CCM, CBM, DMS)

Last week, I reported on south Florida’s record warmth and indicated that more records were likely to be broken. This week, I get to report that several south and central Florida locales have again set some warm temperature records. A total of seven occurred in the three-day period encompassing Christmas. Here they are:

Dec. 24

…RECORD HIGH TEMPERATURE (88) SET AT FORT MYERS…THIS TIES THE OLD RECORD OF 88 SET IN 1981.

Dec. 25

…RECORD HIGH TEMPERATURE (88) SET AT FORT MYERS…THIS BROKE THE OLD RECORD OF 87 SET IN 2015.

Dec. 26

…FOR A THIRD DAY IN A ROW, RECORD HIGH TEMPERATURE (88) SET AT FORT MYERS…THIS BROKE THE OLD RECORD OF 87 SET IN 2015.

Dec 25

…RECORD HIGH TEMPERATURE (85) SET AT MIAMI…THIS TIED THE OLD RECORD OF 85 SET IN 1941.

Dec 26

…RECORD WARM LOW TEMPERATURE (75) SET AT MIAMI…THIS BROKE RECORD OF 74 DEGREES SET IN 1911.

Dec 24

…RECORD HIGH TEMPERATURE (85) SET AT TAMPA…THIS BROKE THE OLD RECORD OF 84 SET IN 2015.

Dec 25

…RECORD HIGH TEMPERATURE (86) SET AT TAMPA…THIS TIED THE OLD RECORD OF 86 SET IN 2015.

Note that for Miami, temperature records date back to 1895.

This will be the end of warm temperature records for 2015 as a trend toward significantly cooler temperatures has already begun and will intensify by tomorrow evening. A large, modified Pacific air mass will be pushing through the area, at that time, along with gusty northerly winds. Expect winds to get into the small craft advisory category in nearshore and offshore waters and possibly over larger inland lakes (including Lake Okeechobee).

Temperatures should tumble into the 50’s by Friday morning and only rise to the mid and upper 60’s Friday afternoon. Saturday morning will see the mercury dip well into the 40’s inland, with readings near 50 along the coast.

Then, as is typically the case, the arrival of cooler and drier air will be short-lived. Once winds become easterly on Saturday, Atlantic moisture will quickly return. By Sunday, the first day of the new year, daytime highs will again be rising into the lower 80’s.

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

© 2016 H. Michael Mogil

Originally posted 12/28/16

weather

A National Christmas weather forecast 2016 (H. Michael Mogil, CCM, CBM, DMS)

Mrs. Claus, wanting to be sure her husband was safe on his Christmas Eve journey, turned to Santa and asked, “What’s the weather forecast?”

Santa, in his usual jolly self, replied, “Rain, dear, in many places; only some snow across the western States during my nighttime ride; heavy snow and blizzard conditions across parts of the northern Plains tomorrow, along with a chance of severe weather across the central Plains.”

Not necessarily a “ho-ho-ho” forecast, but one that takes into account reality. Not to worry, though, Santa and his sleigh are equipped with the latest in aviation weather equipment.

A major winter-spring storm will be moving across the inter-mountain West today and then rapidly intensify as it heads toward the eastern Dakotas on Sunday (Fig. 1 and Fig. 2).

To the north of the storm track, heavy snow and blizzard conditions are likely, especially across the high Plains of the Dakotas and western Nebraska (Fig. 3).

To the south of the storm track, warm and humid air, interacting with a strong jet stream and diffluent winds aloft, will increase the risk of severe weather. Hail and high winds are the most likely risks under a NOAA Storm Prediction Center (SPC) outlook for marginal severe weather activity (Fig. 4).

In between, there will a zone of mixed frozen wintry precipitation, including freezing rain and sleet.  Parts of west-

central Minnesota are now under freezing rain warnings. Given that the SPC outlook indicates thunderstorms are possible as far north as the mixed frozen precipitation area, locally heavier icing is possible. And, if the thunder zone spreads even further north, which it could, given the expected negatively-tilted (northwest-to-southeast) upper level trough (Fig. 5), thundersnow is not out of the question. Thundersnow is Jim Cantore’s (meteorologist at The Weather Channel) apparent new weather favorite!

Once today’s early day rain pattern clears the East Coast, most areas to the east and south of all this major storminess weather event (except for parts of the Great Lakes), should have great weather on Christmas Eve day and Christmas Day. It should be seasonally or unseasonably warm and pleasant in most areas with only limited chances of precipitation.

From my wife and I, Merry Christmas and Happy Hanukah to all of our readers and their families.

© 2016 H. Michael Mogil

Originally posted 12/24/16

weather

Record Florida warmth (H. Michael Mogil, CCM, CBM, DMS)

A persistent upper level ridge (Fig. 1) across Florida and a jet stream far to the north of Florida have both prevented most cold air intrusions from reaching into the Sunshine State. The result has been a very dry and very warm autumn.

In recent days, however, this pattern of warmth has trumped Florida weather stories. While the northern states have experienced cold and snow, it is the snowbirds who have been flocking to south Florida in large numbers.

To support my case, here are just a few of the many record warm temperature records that have been shattered or tied in the past few days:

Dec. 14

…RECORD HIGH TEMPERATURE (87) SET AT MIAMI…THIS BREAKS THE OLD RECORD OF 86 SET IN 1900.

Dec 17

…RECORD HIGH TEMPERATURE (85) TIED AT MIAMI…THE OLD RECORD OF 85 WAS SET IN 1965.

…RECORD WARM LOW TEMPERATURE (76) BROKEN AT MIAMI…THIS BROKE RECORD OF 75 DEGREES SET IN 2015.

Dec 18

…RECORD WARM LOW TEMPERATURE (79) BROKEN AT MIAMI YESTERDAY…THIS BROKE THE RECORD OF 74 DEGREES SET IN 1933.

…RECORD WARM LOW TEMPERATURE (78) SET AT KEY WEST…THIS BREAKS THE OLD RECORD OF 77 SET IN 1967. TEMPERATURE RECORDS FOR KEY WEST DATE BACK TO 1872.

…RECORD HIGH TEMPERATURE SET AT LAKELAND (89)…THIS BREAKS THE OLD RECORD OF 84 DEGREES SET IN 2015.

…RECORD HIGH TEMPERATURE (84) TIED AT TAMPA…THIS RECORD WAS SET IN 1933.

…RECORD WARM MINIMUM TEMPERATURE (69) BROKEN AT MELBOURNE…THIS BREAKS THE PREVIOUS RECORD WARM MINIMUM TEMPERATURE OF 68 DEGREES SET IN 1961.

Dec. 19

…RECORD HIGH TEMPERATURE (87) WAS SET AT MIAMI…THIS BREAKS THE OLD RECORD OF 85 DEGREES SET IN 1989.

…RECORD HIGH TEMPERATURE (84) WAS TIED AT TAMPA…THIS RECORD WAS LAST SET BACK IN 1956.

…RECORD HIGH TEMPERATURE (83) WAS TIED AT ST PETERSBURG – ALBERT WHITTED…THIS RECORD WAS SET BACK IN 1967.

Note that the Key West record includes the length of the historical weather record. This information is not always included in official “record reports.” Hence, some records may only be short-term, be more likely to be broken, and are less representative of longer-term trends (e.g., 50 to 100 years or more).

Based on long-term computer models, more south Florida warm temperature records will likely fall between now and New Year’s Eve.

© 2016 H. Michael Mogil

Originally posted 12/20/16

climate, geography, weather

A real cold front is heading to Florida (H. Michael Mogil, CCM, CBM, DMS)

South Florida experiences “cool front” passages fairly often during the chillier months of the year. These bring wind shifts (winds northerly and northwesterly, quickly turning to northeasterly), and a modest drop in temperatures and a more significant drop in dew point temperatures. In summer months, very weak “cool fronts” occasionally reach as far south as places like Tampa and Orlando, and even less frequently to Naples and Fort Lauderdale.

fig001-sfc-fcst-161209-12zNow, a bona fide arctic cold front is enroute to the sunshine state and should pass by the Naples area on Thursday evening and be fully in control by Saturday (Fig. 1). No, arctic temperatures won’t reach this far south, but the temperature drop will be substantial. From daytime highs in the low to mid 80’s, temperatures in the Naples-Fort Myers area will tumble into the upper 60’s to near 70 by Friday. Overnight lows, which have remained in the uber-humid low to mid 70’s, will dip into the upper 40’s inland and lower 50’s in coastal population centers. This means that the Naples area will transition from temperatures that have been running about 6 degrees warmer than average so far this month to some 10 degrees colder than average by Friday and Friday night. That’s a 16-degree swing! For this time of year, the average high and low temperatures in Naples are 78 and 58, respectively.

Gusty winds will make the chill feel worse than it really is.

Although rain chances for the next several days are only 20 to 30 percent, once the initial non-arctic front passes through the Naples area by tonight, cloudy skies will rule until the arctic front sweeps things clear by Saturday.

Then, as quickly as it came, the cold air will be replaced by moderating temperatures and humidity as winds swing to the northeast by Saturday.

Keep looking to the northwest, though. Given the evolving upper level flow pattern, a string of Pacific weather systems, and periodic southward pushes of the polar vortex, additional cold air outbursts may be heading our way soon. Regardless of how the temperature evolves, dry weather should dominate for the next several weeks.

© 2016 H. Michael Mogil

Originally posted 12/6/16