NWS Miami Declares May 16th as Start of 2010 Rainy Season

[gatorcane]

Here is the definition according to NWS Miami:

Definition of Summer Season
As stated above, the summer season is characterized by warm tempera- tures. Daily Maxima average in the upper 80s. but more significantly, the daily minima average in the middle 70s. Low temperatures rarely lower below the 70 degree level during the summer months. in addition to warm temperatures, high humidities prevail throughout the summer. The dew-point temperature is the best measure of moisture levels in Florida. During the summer period, the dew-point temperature remains in the lower to middle 70s. In addition, convection in the form of showers and thunderstorms is almost a daily occurrence during the summer. In an easterly wind regime, the precipitation occurs as late night and morning showers or thunderstorms over the coastal areas, and afternoon thunderstorms over the interior sections. In a westerly wind regime, afternoon thunderstorms affect interior and coastal areas alike. In light wind conditions, afternoon thunderstorms again develop over southeast Florida and affect most areas. Overall, the best indicators of summer season in southeast Florida are dew-point temperatures and minimum temperatures remaining in the 70s, and frequent daily rainfall.

http://www.srh.noaa.gov/mfl/?n=summer_season

Typically it starts the third week in May on average, but it has started as early as late April in the past.
Looking at the next 7 days it certainly very close if not meeting this criteria. Granted the actual summer storms and showers are not present at the percentage levels you would normally see, however, the definition above does not include % of POPS.

Note this snippet from that article which discusses the emphasis on POPS:

Prior to 1965, only the daily minimum temperature and 24-hour precipitation amounts were available. For determining the beginning (or ending) of the summer season, more weight was placed on the minimum temperatures remaining above (or below) 70oF than on the occurrence of precipitation. Most often, the beginning (ending) of the rains occurred on or just a few days after (before) the date when the minimum temperatures ceased to fall (fell) below 70oF. This was also true in the later years of the study

[Sanibel]

The feel and humidity are here but the diurnal showers aren't.

[Patrick99]

Difficult to say, but perhaps it has. No POPS, but the dewpoints are there, and the daily minima are easily there.

The only thing I might cite is that it may not be hot enough. Forecasted high of 83 today with full sun isn't rainy season-esque to my mind. Now toward the end of this forecast period we may get more toward the higher temps. I bet they'll peg the rainy season as having started somewhere around May 6-7.

[gatorcane]

Difficult to say, but perhaps it has. No POPS, but the dewpoints are there, and the daily minima are easily there.

The only thing I might cite is that it may not be hot enough. Forecasted high of 83 today with full sun isn't rainy season-esque to my mind. Now toward the end of this forecast period we may get more toward the higher temps. I bet they'll peg the rainy season as having started somewhere around May 6-7.

Today the temps were held down somewhat due to all of the low-level stratus/cumulus that seemed to form over much of metro SE FL. That certainly is not summer-like at all. So it hasn't started yet. But looking at the extended forecast for the next 7 days, looks like a summer-like forecast to me with a nice H5 and lower-level ridge (i.e Bermuda High) setting up shop in the Western Atlantic east of Florida. Wouldn't be surprised that the summer "rainy" season officially starts sometime this week. All depends on what date they want to choose. Technically it could be even tomorrow if highs make it to the forecast highs in the upper 80s. Lows are in the mid 70s all week. Dewpoints are above 70F as well (Currently 72F at Palm Beach International even in the afternoon).

Looking at the data since midnights at PBI, the dewpoint did hit 69F late last night and the highs were only in the low 80s today with extensive cloud cover. So the rainy season has not quite started but it is very close:

01 16:53 SE 14 10.00 Mostly Cloudy FEW016 BKN022 81 72 29.99 1015.6
01 15:53 SE 15 10.00 Mostly Cloudy BKN018 81 72 30.01 1016.3
01 14:53 SE 16 10.00 Mostly Cloudy BKN020 81 72 30.03 1016.8
01 13:53 SE 15 10.00 Mostly Cloudy BKN022 82 72 84 77 30.04 1017.3
01 12:53 SE 15 10.00 Overcast OVC023 82 72 30.06 1017.7
01 11:53 SE 16 10.00 Overcast OVC024 82 72 30.06 1018.0
01 10:53 SE 14 10.00 Overcast OVC022 80 71 30.06 1017.8
01 09:53 SE 15 10.00 Mostly Cloudy BKN019 80 71 30.04 1017.3
01 08:53 SE 10 10.00 Mostly Cloudy BKN020 79 71 30.04 1017.1
01 07:53 SE 12 10.00 A Few Clouds FEW025 77 71 77 75 30.02 1016.6
01 06:53 SE 10 10.00 Partly Cloudy FEW023 SCT120 76 70 30.00 1015.9
01 05:53 SE 9 10.00 Partly Cloudy FEW022 SCT120 75 70 29.99 1015.4
01 04:53 SE 10 10.00 A Few Clouds FEW120 75 69 29.99 1015.4
01 03:53 SE 12 10.00 A Few Clouds FEW120 75 69 29.98 1015.1
01 02:53 SE 10 10.00 Mostly Cloudy FEW018 BKN120 75 69 29.99 1015.4
01 01:53 SE 13 10.00 Mostly Cloudy FEW017 BKN100 76 70 77 76 30.00 1015.7
01 00:53 SE 14 10.00 Mostly Cloudy FEW017 BKN100 76 70 30.01 1016.2

[gatorcane]

Last night the dewpoint did not drop below 70F at Palm Beach. Low was 75F. High today is in the upper 80s. I believe the summer rainy season has begun today and NWS Miami may declare that also:

02 09:53 SE 13 G 24 10.00 Partly Cloudy SCT022 SCT110 81 70 30.06 1018.0
02 08:53 SE 16 G 24 10.00 Partly Cloudy SCT021 80 70 30.06 1017.7
02 07:53 SE 14 10.00 Partly Cloudy SCT019 77 70 77 75 30.04 1017.2
02 06:53 SE 12 10.00 Partly Cloudy SCT018 76 71 30.03 1016.7
02 05:53 SE 13 10.00 Mostly Cloudy SCT015 BKN032 76 71 30.01 1016.0
02 04:53 SE 12 10.00 Partly Cloudy SCT014 76 72 30.00 1015.8
02 03:53 SE 13 10.00 Mostly Cloudy FEW012 BKN030 76 72 30.00 1015.6
02 02:53 SE 12 10.00 A Few Clouds FEW018 76 73 30.01 1016.0
02 01:53 SE 14 10.00 Partly Cloudy SCT018 76 73 78 75 30.02 1016.6
02 00:53 SE 12 10.00 A Few Clouds FEW020 77 73 30.03 1016.9

http://www.weather.gov/data/obhistory/KPBI.html

and here you go with the summer-time wording in the extended:

WEDNESDAY THROUGH THE END OF THE WEEK... THE MID LVL RIDGE WILL
FINALLY BREAK DOWN AS A TROF MOVES INTO THE SE STATES. HI TEMPS
WILL COOL EVER SO SLIGHTLY AND RAIN CHANCES WILL INCREASE. FORECAST
SOUNDINGS INDICATE THAT INTERIOR LOCATIONS MAY EXPERIENCE SCT
TSRA, ESPECIALLY AS SEA BREEZES COLLIDE, AS HIGH TEMPS CONTINUE TO
BE NEAR 90 ALONG WITH DEWPTS IN THE LOW 70S, BUT THE BIGGEST CHANGE
WILL OCCUR IN THE MID LVLS AS 500MB TEMPS COOL SOME 10C AS THE CAP
DISSIPATES

http://forecast.weather.gov/product.php ... glossary=1

[jinftl]

From the 'winter' that wouldn't end to an early start to the rainy season....what a transitioN! Nighttime temps in the 40s and 50s are now a fading memory!

Last night the dewpoint did not drop below 70F at Palm Beach. Low was 75F. High today is in the upper 80s. I believe the summer rainy season has begun today and NWS Miami may declare that also:

02 09:53 SE 13 G 24 10.00 Partly Cloudy SCT022 SCT110 81 70 30.06 1018.0
02 08:53 SE 16 G 24 10.00 Partly Cloudy SCT021 80 70 30.06 1017.7
02 07:53 SE 14 10.00 Partly Cloudy SCT019 77 70 77 75 30.04 1017.2
02 06:53 SE 12 10.00 Partly Cloudy SCT018 76 71 30.03 1016.7
02 05:53 SE 13 10.00 Mostly Cloudy SCT015 BKN032 76 71 30.01 1016.0
02 04:53 SE 12 10.00 Partly Cloudy SCT014 76 72 30.00 1015.8
02 03:53 SE 13 10.00 Mostly Cloudy FEW012 BKN030 76 72 30.00 1015.6
02 02:53 SE 12 10.00 A Few Clouds FEW018 76 73 30.01 1016.0
02 01:53 SE 14 10.00 Partly Cloudy SCT018 76 73 78 75 30.02 1016.6
02 00:53 SE 12 10.00 A Few Clouds FEW020 77 73 30.03 1016.9

http://www.weather.gov/data/obhistory/KPBI.html

[gatorcane]

From the 'winter' that wouldn't end to an early start to the rainy season....what a transitioN! Nighttime temps in the 40s and 50s are now a fading memory!

Last night the dewpoint did not drop below 70F at Palm Beach. Low was 75F. High today is in the upper 80s. I believe the summer rainy season has begun today and NWS Miami may declare that also:

02 09:53 SE 13 G 24 10.00 Partly Cloudy SCT022 SCT110 81 70 30.06 1018.0
02 08:53 SE 16 G 24 10.00 Partly Cloudy SCT021 80 70 30.06 1017.7
02 07:53 SE 14 10.00 Partly Cloudy SCT019 77 70 77 75 30.04 1017.2
02 06:53 SE 12 10.00 Partly Cloudy SCT018 76 71 30.03 1016.7
02 05:53 SE 13 10.00 Mostly Cloudy SCT015 BKN032 76 71 30.01 1016.0
02 04:53 SE 12 10.00 Partly Cloudy SCT014 76 72 30.00 1015.8
02 03:53 SE 13 10.00 Mostly Cloudy FEW012 BKN030 76 72 30.00 1015.6
02 02:53 SE 12 10.00 A Few Clouds FEW018 76 73 30.01 1016.0
02 01:53 SE 14 10.00 Partly Cloudy SCT018 76 73 78 75 30.02 1016.6
02 00:53 SE 12 10.00 A Few Clouds FEW020 77 73 30.03 1016.9

http://www.weather.gov/data/obhistory/KPBI.html

indeed it certainly transitioned fairly quickly. Also mention of summer-like POPS for later on this week as we begin to see cooling at the H5 layer and as a front dangles around South FL or just north of it bringing in more of a SW flow perhaps....

[gatorcane]

Big time summer-time pops yesterday for parts of south Florida. Looks like another round this afternoon with potential severe storms. Rainy season seems to have begun.

[Evil Jeremy]

I agree Gator. Its the classic seabreeze pattern this afternoon. Lets see if it holds up. Last year once the pattern started one day, it didn't stop.

[tropicana]

..and a record high temperature of 93F at Miami International this afternoon

[Patrick99]

Yeah, it was hot hot hot all day in my area. Miami and points south did not get in on any of the activity. Wonder why? Storms were supposed to drift back toward the metro areas, but everything down here just kinda fell apart.

[Sanibel]

Feels like an early summer here. The temperature is a few degrees below summer as well as the humidity but this is still slightly early.

[Patrick99]

Temperature's up at normal summer levels in South Florida, probably even a little above normal. And the low-level moisture has been quite high, with humidity percentages in the upper 60s and 70s even in the afternoon, triple digit heat indices.

Only thing missing is the rain. I see the clouds rising inland, but it's like there's a shield over the city, any activity falls apart before it gets here.

[Sanibel]

Our house thermostat will show an 86* to 87* degree temperature with the air conditioner off in summer. It got up to around 83* recently. Not quite summer because the Gulf is still not at summer SST. It does feel like summer though.

There was one good seabreeze convergence thunderhead over the mainland yesterday.

[gatorcane]

So maybe this is the true start:

NWS Miami snippet:

HOWEVER...THINGS LOOK TO CHANGE NEXT WEEK. THE DEEP LAYERED MEAN
RIDGE WILL MOVE EAST INTO THE ATLANTIC WHILE A TROUGH DIGS INTO
THE EASTERN STATES. SW FLOW WILL PUMP MUCH HIGHER MOISTURE INTO
THE AREA FROM THE CARIB...WITH GFS SHOWING PWATS CLIMBING INTO
THE 1.75-2" RANGE BY LATE MON/TUE...ALONG WITH INCREASING
INSTABILITY AS MID LEVELS COOL. THIS LOOKS TO SET THE STAGE FOR A
MORE ACTIVE WEATHER PATTERN WITH DAILY TSTORMS POSSIBLE NEXT
WEEK. IF MODELS CONTINUE TO SHOW THIS PATTERN EVOLVING THEN
POPS/TSTORM COVERAGE WILL NEED TO BE INCREASED. HOWEVER...GIVEN IT
BEING SO FAR OUT...MADE NO CHANGES TO THE EXTENDED FCST.

http://forecast.weather.gov/product.php ... glossary=1

[Patrick99]

Yeah, I have to think next week will be the kicker.

Too many consecutive days of sub-70 dewpoints this week.

[gatorcane]

Looks like the rainy season has officially started according to NWS Miami:

http://www.srh.noaa.gov/images/mfl/news ... on2010.pdf

Curiously, however, I don't see a hotlink on the main page of the NWS site....had to dig for this.

[Patrick99]

Interesting. And a cool picture too.

[gatorcane]

Yesterday marked the first day I actually felt the humidity here in South FL with the usual situation where I am outside for a few minutes and start to sweat. Scattered to numerous thunderstorms blew up to our west over the Everglades and Lake O with large anvils building in the skies to our west. Noticed numerous storms blew up yesterday throughout the peninsula also from about Orlando south.

I do believe the true start to the rainy season was yesterday (May 28th) looking at the extended forecast and feeling the noticeable uptick in humidity. I wonder of NOAA did not post that link until they knew for sure.

[Aquawind]

I noticed the same thing yesterday and this morning as well..Starting to feel like the juicey hot summer weather I am familiar with. The daily precip chances 30%+ as well throughout the forecast.