Southeast Florida Weather Discussion 12-31-12

The Weather Center News, Southeast Florida, Weather

Happy New Year!

It was mainly partly cloudy overnight (except for the well inland areas where it was clear). There was a wide variation of temperatures. At approximately 7:30 this morning, Boca Raton, Florida had a temperature of 68 degrees while a reporting site Arther R. Marshall Loxahatchee National Wildlife Refuge had a temperature of 48 degrees. Below are other observations across south Florida (source from WunderMap).

 

Temperatures 12-31-12 (7:33 am)

Temperatures 12-31-12 (7:33 am)

 

The wide variation in temperatures was due to the cloud cover and winds. The clouds and winds (warmer waters of the Atlantic Ocean) prevented the temperatures from dropping much along the east coastal sections.

The overnight temperatures were generally in the 50’s to middle 60’s. Winds already had veered to the east at 10 – 20 mph (lighter winds further inland).

During the day, it was a generally partly cloudy day to occasionally cloudy (mainly along the coast). Highs were uniformly in the low 70’s to upper 70’s. Winds were diminishing and the small craft advisory was dropped this morning. Winds were also veering to the southeast.

The lows tonight will be mainly in the 60’s (it may get close to 70 along the coast). There may be some 50’s further inland.

The warm-up will continue into New Years Day with generally partly sunny/partly cloudy skies. With the winds veering to the southeast and south, moisture will increase a bit. Highs will be around middle 70’s to low 80’s. Lows will be generally in the 60’s to around 70 along the coast. Again, there may be some 50’s further inland. Winds will have diminished and be more in the 5 – 15 mph range from the southeast veering to the south. Boating conditions will have improved with waves of 2 – 5 feet with a moderate chop.

On Wednesday, the skies will be partly sunny/partly cloudy. Highs will be upper 70’s to low 80’s. Lows will be in the 60’s to 70. Winds will generally be from the southeast and south at 5 – 10 mph.  Wave heights at around 2 feet with a light chop.

On Wednesday night/Thursday, a front will move into north Florida and move very slow southward. By later Thursday/Thursday night, the front will be closer and with moisture in place, it may be enough to generate some showers/slight chance of thundershower activity. It will be generally partly cloudy. Highs will be upper 70’s to middle 80’s. Lows will generally be in the 60’s. Winds will be out of the south, veering southwest at 5 – 15 mph. Seas will be around 2 feet with waters a light chop.

Friday will become mostly cloudy as the front inches closer to the area. The front may clear southeast Florida later on Friday. The chance of showers and slight chance of thundershowers will continue. Highs will be in the upper 70’s to middle 80’s. Lows will range in the 60’s. Winds will be out of the southwest at 5 – 15 mph. Seas will be 2 – 5 feet. Depending on the location of the front, winds will shift to the north to northeast and increase. After frontal passage, winds will increase to 10 – 20 mph.

There is some uncertainty on the movement and timing of this frontal system as it moves generally southward. The temperatures, clouds, showers and winds may need to have adjustments made accordingly. There will not be a drastic cool down. By the time the front makes it into southeast Florida, the high will have moved far enough east that the winds will have already turned to the northeast. Also in looking at the forecast models, there may be a breezy/windy period after frontal passage. If this verifies, boating conditions will deteriorate.

As mentioned yesterday, there is a robust upper level high over southern Bahamas/northern Caribbean. Notice all that dry air (brown color) surrounding this high.  There is a rough drawing of the upper level flow around the high.

 

Water Vapor Image 12-31-12 (6:15 pm)

Water Vapor Image 12-31-12 (6:15 pm)

 

This high will temporarily weaken and move away a little. After the upper level trough moves away, forecast models has this high rebuilding, expand and move closer the southeast U.S. coast. This will lead to warmer weather and less frequent frontal passages (if any).  Winter may disappear for a while in south Florida.

Of interest is that there is something called the NAO (North Atlantic Oscillation).  This index measures the difference of pressures between the Subpolar low and the Azores High. These differences of pressures effect the wind flow across the northern hemisphere. A positive NAO tends to have warmer weather over the eastern U.S. and a negative NAO conversely tends to have colder temperatures over the eastern U.S.  The CPC (Climate Prediction Center) has a good explanation of this index and its effects.  There is also additional information here on the NAO index.  This index is only good as a predictor for about two weeks in advance.  Of course, there are other factors that could effect temperatures/weather.   For the past few weeks, the NAO index has been rising.

 

 

NAO Index 12-31-12

NAO Index 12-31-12

 

The forecast models has the NAO index decreasing toward the end of January.

 

Southeast Florida Weather Discussion 12-30-12

The Weather Center News, Southeast Florida, Weather

 

After the frontal passage Saturday night, it turned cooler, breezier and dryer. It was a cool/cold start for this morning. Temperatures generally ranged around 50 – 55 degrees (with some upper 40’s further inland). Palm Beach County had general temperatures in the mid 40’s – 50 degree range. With the winds out of the north at 10 – 20 mph and occasionally higher, it made it feel colder.

Satellite images this morning indicated low level clouds lurking just offshore the east coast. The colder air moving over the warmer Atlantic waters were causing these clouds to form. As the winds veer to the northeast, these clouds will be coming ashore.  Below is two satellite images illustrating the clouds off shore the Atlantic Ocean  moving in.  On the first image, the band of clouds from the western Bahamas through Cuba into the northwestern Caribbean is associated with the front that passed through Saturday night.   Also, note the shadow effect along the west coast of Florida.

 

Satellite Image 12-30-12 (8:15 am)

Satellite Image 12-30-12 (8:15 am)

Satellite Image 12-30-12 (4:15 pm)

Satellite Image 12-30-12 (4:15 pm)



The day was mostly sunny early, but clouds were moving in. It was rather cool especially with the wind. Highs ranged from mid 60’s to low 70’s. Winds were out of the north veering to the northeast at 15 – 25 mph. Boating conditions was hazardous with a small craft advisory was in effect.

 

For tonight, as winds are from the northeast, some clouds will continue to be blown in (especially along the coast). Temperatures will range from middle 50’s to middle 60’s. Inland areas that are cloud free and winds become light may see cooler temperatures to around 50.

 

Looking at the radar imagery, clouds are building off the southeast coast this evening. Some of them may be able to generate sprinkles.  They may move in along the coastal sections in the morning.

 

Radar Image 12-30-12 (8:54 pm)

Radar Image 12-30-12 (8:54 pm)

 

It will be mostly partly cloudy with periods of cloudiness especially along the coast on Monday. With that cloudiness, sprinkle/shower cannot be ruled out (especially along the coastal sections). This is would be most likely during the night and morning hours. It will still remain rather breezy. Highs will be in the low to middle 70’s. Lows will generally be in the 60’s to around 70 along the coast. There may be some 50’s further inland. Winds will be from the east at 10 – 20 mph with seas at 3 – 6 feet and higher off shore. Winds will be veering to the east-southeast at lighter speeds Monday night. Waters will be choppy. A small craft advisory (at least for the morning) will continue to be in effect. They may be dropped later in the day.

 

The warm-up will continue into New Years Day with generally partly cloudy skies. Winds will be east and southeast.  The slight chance of showers/sprinkles will continue especially along the coastal sections and during the night and morning hours. Highs will be middle 70’s to low 80’s. Lows will be generally in the 60’s to low 70’s along the coast. Winds will have diminished and be more in the 10 – 15 mph range. Boating conditions will have improved with waves of 2 – 5 feet with a moderate chop.

 

On Wednesday, the skies will be mainly partly cloudy. Temperatures will continue to warm.  It will also become more humid.  The slight chance of a shower will continue. Highs will be upper 70’s to middle 80’s. Lows will be in the middle 60’s to low 70’s. Winds will generally be from the southeast possibly veering to the south at 5 – 15 mph with wave heights at around 2 feet with a light chop.

 

On Thursday, it will be mainly partly cloudy with a chance of showers. Highs will range from around 80 to middle 80’s. Lows will be generally in the 60’s to low 70’s. Winds will be south and veering southwest late. Waters will have a light chop and waves will be around 2 feet.

 

On Friday the next front will be approaching. The front will be a slow mover through the state. Frontal passage will be either Friday or Saturday. It will not be a clean passage (at least not immediately). This may also mean an extended period of cloudiness and enhanced/periods of rain or showers as weak impulses/waves move along the front .  The high behind the front will move quickly eastward and winds will veer quickly to the northeast. If this verifies, it will not be a big cool down.

 

 

HPC Forecast 1-4-13  (7:00 am)

HPC Forecast 1-4-13 (7:00 am)

HPC Forecast 1-5-13  (7:00 am)

HPC Forecast 1-5-13 (7:00 am)



There is a upper level high over the northern portion of the Caribbean.  That upper level high is causing quite a bit of dry air (brownish color) in that area.  It is also making it tough for upper level troughs from the west to dig south. This is preventing the real cold air from getting this far south. Made a rough drawing of the flow around the high. Also, the streak of moisture (milky/white area)  across central Florida is the northern fringes of that high.  Eventually the upper level trough from the west will shove it east and southeast.  However, rather than that upper level trough to move due east, it will pivot and turn northeast as it runs into that high.

 

Water Vapor Image 12-30-12 (7:15 pm)

Water Vapor Image 12-30-12 (7:15 pm)

 

 

Southeast Florida Weather Discussion 12-29-12

The Weather Center News, Southeast Florida, Weather

It was much warmer overnight than compared to 24 hours ago. Temperatures were very uniform throughout the area. The temperatures ranged from mid 60’s to low 70’s. This was the result of the clouds, higher humidity and winds.  The winds were light from the south.

The front was making its way down the state accompanied by a band of clouds and showers. The band of showers was weakening as it headed down the state.

 

Radar 12-29-12 (7:28 am)

Radar 12-29-12 (7:28 am)

Radar 12-29-12 (5:18 pm)

Radar 12-29-12 (5:18 pm)



The highs ranged around 80 – middle 80’s. Winds veered from the south to southwest and then west. The winds in front of the front were not as strong as the previous front as the low pressure area attending the front is not strong. The winds will be generally 10 – 20 mph. The parent low will be “bombing out” (significant intensification) off the coast of northeast U.S. coast/Canadian Maritimes. They will be getting strong winds and heavy snow.

Frontal passage will occur tonight. Winds will shift to the northwest and increase markedly (15 – 25 mph). Seas will respond with deteriorating boating conditions and small craft advisories are in effect.

It will be much cooler and drier tonight. Lows will generally be in the 50’s with some 40’s possible in the colder areas further inland. The cooler drier air will be short lived as the high behind the front will scoot out quickly and winds will veer to the northeast.

The high behind the front is strong and will keep a fairly tight pressure gradient.  Below is the GFS forecast model illustrating the tight pressure gradient where the lines of equal pressure are close together. This tight pressure gradient will keep winds up for a couple of days.  Also, notice that very intense low off the Canadian Maritimes and how close those lines are.

 

GFS Model 06z 12-29-12-18 HR

GFS Model 06z 12-29-12-18 HR

 Model 06z 12-29-12-60 HR

Model 06z 12-29-12-60 HR



Sunday will be cooler. It will be mostly sunny and breezy. Clouds may be on an increase especially along the coast later in the day as the winds veer to the northeast. Highs will generally range from the upper 60’s to low 70’s. Lows will primarily in the 50’s to middle 60’s along the coast. Winds will be from the north veering to the northeast at about 15 – 25 mph. Boating conditions will be rough. Small craft advisories will continue to be in effect in effect.

It will be mostly partly sunny on Monday. It will still remain rather breezy. Highs will be in the mid to upper 70’s. Lows will generally be in the 60’s to around 70 along the coast. There may be some 50’s further inland. Winds will be from the east at 15 – 20 mph with seas at 4 – 6 feet and higher off shore. Winds will be veering to the southeast at lighter speeds Monday night. Waters will be choppy. A small craft advisory or exercise caution statement will probably be in effect.

New Years Day will be partly sunny to partly cloudy. Highs will be upper 70’s to low 80’s. Lows will be generally in the 60’s to low 70’s along the coast. Winds will be veering to the southeast and possibly south. Winds will have diminished and be more in the 10 – 15 mph range. Boating conditions will have improved with waves of 2 – 3 feet with a light to moderate chop.

On Wednesday, the skies will be mainly partly cloudy. With the warmer conditions and increased humidity, shower chances will increase slightly. Also, there will be a front to our north which may enhance shower activity. The proximity of the front will influence the shower chances. Highs will be in the upper 70’s to low 80’s. Lows will be in the middle 60’s to low 70’s. Winds will be mainly from the south at 5 – 15 mph with wave heights at around 2 feet with a light chop.

Thursday will be mainly partly cloudy with a chance of showers. Highs will range from upper 70’s to middle 80’s. Lows may be slightly cooler with lows generally in the 60’s. There may be some 50’s well inland in Palm Beach County. Winds will be veering to the south and southwest as the front approaches.

Looking longer range, there is better consensus among the forecast models. It appears that the next front will approach around the middle of next week and then stall. It will be quasi-stationary for 2 – 3 days (possibly more).

It will stall in the vicinity of north/central Florida. While this happens, there will be weak impulses (lows) moving along the front. This will result in periods of rain in the vicinity of the front. The location of the front will dictate who gets the rain. The front may eventually ooze into south Florida, but that may be questionable. An upper level high will be building over the north Caribbean/southern Bahamas which will tend to deflect systems northward. We may therefore be in an extended period of warmer and more humid weather.

 

HPC Forecast 1-2-13 (7:00 am)

HPC Forecast 1-2-13 (7:00 am)

HPC Forecast 1-3-13 (7:00 am)

HPC Forecast 1-3-13 (7:00 am)


HPC Forecast 1-4-13  (7:00 am)

HPC Forecast 1-4-13 (7:00 am)

HPC Forecast 1-5-13  (7:00 am)

HPC Forecast 1-5-13 (7:00 am)

 

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