Will the Rainy Season Start This Week in Florida?

[gatorcane]

Looking at the forecast here in South Florida, 20% to 40% POPs start Mon. though the weekend with SW flow and afternoon seabreeze storm development. Looked at NWS Tampa and Melbourne offices and they are calling for about the same chance of POPS each day also all the way through next weekend.

However, looking back in history the earliest it has ever started was Apr. 16th back in 1957. The median start date is May 21st so we would be many weeks ahead of schedule:

NWS article on what it meant by "rainy season":
http://www.srh.noaa.gov/mfl/?n=summer_season

NWS Miami snippet:

EXTENDED PERIOD:

THE SURFACE RIDGE HAS BEEN SHOVED TO THE E AND A S TO SW WIND FLOW DEVELOPS AND
INCREASES. THOUGH THE SURFACE FRONT NEVER MAKES IT TO S FLA...THE
ATMOSPHERIC MOISTURE INCREASE WITH THE EXPECTED SEA BREEZE
DEVELOPMENT AND CONTINUED WARM TEMPERATURES...SCATTERED SHOWERS AND
THUNDERSTORMS CAN BE EXPECTED DAILY...MORE SO ON TUES AS SOME DRIER
AIR MOVES OVER THE AREA BY MIDWEEK.

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

Thoughts?

[psyclone]

my guess is no. too soon. this week's convective potential is being enhanced by transient mid latitude features and when they go so will the rain. april is typically a very dry month over the peninsula.

[Patrick99]

The language in the forecast discussions for the upcoming week is definitely that of a rainy season pattern....but I think it's just because of old stale fronts hanging around. Plus current MIA dewpoint is 64. Pretty good for March, wonder if it will make it up to 70 during the week?

I'm guessing that the strong SW Atlantic/Caribbean high will get back in control after this and give us easterly flow with highs around 81-82 and 59-61 dewpoints. Some form of that ridge has pretty much had a lock on S. FL weather since January. From what I remember, I'd say about 95% of the Aprils I've seen have been dry. I remember a small handful, however, when a pretty good squall line came through, and then the front stalled and hung around for over a week giving us decent rain, typically around Easter....I'm guessing those were probably El Nino springs, in retrospect....

[gatorcane]

Summer rainy season lingo disco from NWS, though a front moves in Friday afternoon to put us back into normal end-of-march weather.


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MIAMI FL
131 PM EDT TUE MAR 29 2011

.AVIATION...EVEN THOUGH CONVECTION IS STARTING LATER TODAY. TSTMS
ARE STILL EXPECTED TO DEVELOP OVER INTERIOR SECTIONS AND DRIFT OR
MOVE NORTHEAST THROUGH THE AFTERNOON AND EVENING. EXPECT MOST
ACTIVITY TO BE STEERED CLOSER TO NORTHEASTERN TERMINALS(KFLL,
KFXE, AND KPBI) AS A SURFACE BOUNDARY MOVES NORTH OVER THOSE AREAS, AND
NOT SO CLOSE TO THE SOUTHERN TERMINALS. WL EXPECT WEST COAST SEA
BREEZE TO PUSH ANY SHWR/TSTM WELL INLAND TO KEEP THEM AWAY FROM
KAPF. OTHERWISE, SOUTHEAST FLOW WILL PREVAIL OVER REST OF THE
TERMINALS, DIMINISHING IN SPEED OVERNIGHT, BUT INCREASING AGAIN TO
ABOUT 10-12 KTS BY MID-MORNING WEDNESDAY.

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

[gatorcane]

Just like summer-time, here come the special weather statements as seabreeze-driven convection is firing over the Everglades heading NE into South FL metro areas:

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MIAMI FL
516 PM EDT TUE MAR 29 2011

FLC011-099-292145-
/O.CON.KMFL.SV.W.0008.000000T0000Z-110329T2145Z/
PALM BEACH FL-BROWARD FL-
516 PM EDT TUE MAR 29 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 545 PM EDT
FOR NORTH CENTRAL BROWARD AND SOUTH CENTRAL PALM BEACH COUNTIES...

AT 513 PM EDT...DOPPLER RADAR CONTINUES TO INDICATE A SEVERE THUNDERSTORM
CAPABLE OF PRODUCING GOLF BALL SIZE HAIL...AND DESTRUCTIVE WINDS IN EXCESS
OF 70 MPH. THIS STORM WAS LOCATED 8 MILES WEST OF PARKLAND...MOVING
NORTHEAST AT 10 TO 15 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
PARKLAND...
AND SURROUNDING COMMUNITIES.

SEVERE THUNDERSTORMS CAN ALSO PRODUCE TORNADOES WITH LITTLE OR NO
ADVANCE WARNING. PREPARE TO MOVE TO A PLACE OF SAFETY IN AN INTERIOR
ROOM IN THE LOWEST FLOOR OF YOUR HOUSE OR BUSINESS IF A TORNADO IS
SPOTTED.

THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.

LAT...LON 2626 8043 2632 8049 2652 8027 2629 8021
TIME...MOT...LOC 2115Z 229DEG 13KT 2635 8035

$$

BAXTER

[gsytch]

No, not in Tampa Bay. April is always incredibly dry. In my neck (just N of Tarpon Springs) May si also dry but hot. However, Gulf temps have warmed quickly, so I wonder how that will play into seabreeze storms? Usually the Gulf is still a little cool inMay and the breeze keeps any storms inland from me at the coast. My hose gets heavy duty in Apr/May. But there is hope.........

[gatorcane]

it did not start but there are hints it is around the corner and I wouldn't be surprised if it starts early this year (median start date is May 21st).

Looks like a Thunderstorm has developed in Mainland Monroe off of a Seabreeze boundary, which remind me of the summmer-time rainy season discussions:

SHORT TERM FORECAST
NATIONAL WEATHER SERVICE MIAMI FL
632 PM EDT SUN APR 3 2011

FLZ069-070-075-GMZ656-657-032345-
COASTAL COLLIER-INLAND COLLIER-MAINLAND MONROE-
COASTAL WATERS FROM CHOKOLOSKEE TO BONITA BEACH, FL OUT 20 NM-
COASTAL WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE, FL OUT 20 NM-
632 PM EDT SUN APR 3 2011

.NOW...
ISOLATED SHOWERS WILL CONTINUE TO AFFECT MAINLAND MONROE
COUNTY...TO THE NORTH OF WILDERNESS WATERWAY SOUTH. THE SHOWERS
WILL CONTINUE IN A BAND TO THE NORTHWEST INTO SOUTHERN COLLIER
COUNTY...AFFECTING AREAS IN AND AROUND EVERGLADES CITY. A
THUNDERSTORM IS POSSIBLE IN THIS AREA...CONTAINING A FEW
LIGHTNING STRIKES AND GUSTY WINDS OF UP TO 35 MPH. ADDITIONAL
SHOWERS WILL LIKELY DEVELOP FURTHER TO THE NORTH OVER COLLIER
COUNTY...JUST INLAND FROM THE GREATER NAPLES AREA WHERE THE GULF
SEA BREEZE IS LOCATED. THE ACTIVITY WHICH DEVELOPS WILL MOVE
TOWARDS THE WEST AT AROUND 5 MPH...POSSIBLY INTO THE NAPLES
AREA...THOUGH IT LOOKS AS THOUGH AREAS FURTHER INLAND HAVE THE
BETTER CHANCE FOR RAIN.

http://forecast.weather.gov/showsigwx.p ... m+Forecast

[gatorcane]

Hmmm..

HIGH PRESSURE WILL BUILD TO OUR NORTH WEDNESDAY INTO THURSDAY.
SLIGHTLY COOLER TEMPERATURES ARE EXPECTED WEDNESDAY ON WEAK COLD
AIR ADVECTION...BEFORE TEMPERATURES REBOUND RAPIDLY THURSDAY. THE
WEATHER PATTERN WILL BECOME SUMMER-LIKE FRIDAY THROUGH THE
WEEKEND AS THE HIGH SHIFTS INTO THE WESTERN ATLANTIC AND AN
EASTERLY FLOW RESUMES. AN UPPER LEVEL RIDGE WILL ALSO STRENGTHEN
THROUGH THE PERIOD, WITH H85 TEMPS WARMING TO 16C BY SATURDAY.
DAYTIME HIGHS FRIDAY THROUGH MONDAY WILL BE MAINLY UPPER 80S TO
LOW 90S. A FEW SHOWERS ARE ALSO POSSIBLE, ESPECIALLY NEAR AND
ALONG THE EAST COAST, BUT PROBABILITY AND COVERAGE TOO LOW TO
INCLUDE IN FORECAST AT THIS TIME.

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

[gatorcane]

I am not so sure it hasn't already started. Looks like we are getting good POPs and seabreeze convergence in Southern FL the past several days with temps in the 70s+ at night and near 90F during the day...

Huge storms now developing east of Lake O in Northern Palm Beach and big T-storms in Miami-Dade and southern Broward yesterday....all seabreeze driven, enhanced by a washed out front, typical of June

[gatorcane]

POPS raised to 50%

000
FXUS62 KMFL 181938 AAB
AFDMFL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MIAMI FL
333 PM EDT MON APR 18 2011

...UPDATED TO INCREASE POPS AND TO ADD STRONG STORMS TO THE EAST
COAST METRO AREAS THIS AFTERNOON INTO EARLY THIS EVENING...

.UPDATE...
STRONG STORMS ARE DEVELOPING OVER INLAND BROWARD AND PORTIONS OF
PALM BEACH COUNTY THIS AFTERNOON ALONG THE COLLISION OF THE EAST
AND WEST COAST SEA BREEZES. STRONG STORMS SHOULD CONTINUE TO
DEVELOP LONG THE BOUNDARY THROUGH THE LATE AFTERNOON INTO THE
EARLY EVENING HOURS AND PUSH BACK TOWARDS THE EAST COAST METRO
AREAS....AS THE STEERING FLOW IS FROM THE WEST TO NORTHWEST
DIRECTION. THE LATEST RUC 13 AND WRF MODELS ARE ALSO SHOWING
SHOWERS AND THUNDERSTORM ACTIVITY TO DEVELOP OVER THE EASTERN
INTERIOR AREAS AND PUSH BACK TO THE EAST COAST METRO AREAS THROUGH
THE EARLY EVENING HOURS. THEREFORE...THE POPS ALONG THE EAST COAST
METRO AREAS WILL BE RAISE TO 50 PERCENT COVERAGE FOR REST OF THIS
AFTERNOON INTO EARLY THIS EVENING.

THE LATEST GOES SATELLITE IMAGES ARE ALSO SHOWING THAT THE 500 MB
TEMPS HAVE COOLED DOWN TO AROUND -14C THIS AFTERNOON. WITH THE MID
LEVEL OF THE ATMOSPHERE VERY COLD AND THE SURFACE TEMPS IN THE
UPPER 80S TO AROUND 90...THERE IS A THREAT FOR HAIL UP TO QUARTER
SIZE THIS AFTERNOON INTO EARLY THIS EVENING. SO WILL MENTION THIS
IN THE ZONE PACKAGE FOR THE EAST COAST METRO AREAS AND IN THE
AFTERNOON HWO PACKAGE

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

[AdamFirst]

The storm that developed over western Martin and St. Lucie Counties earlier this afternoon has triggered multiple brush fires, thanks to the lightning.

[gatorcane]

More importantly low temperatures have not dropped below 70F at Palm Beach International and the dew point has stayed generally 70F or higher since Apr. 15th.

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

[NDG]

I think we are seeing a typical weak but short start to our rainy season, which is helped by a dying frontal boundary in combination of 70+ deg dewpoints & daytime heating but once the boundary effects die out in a couple of days we are going to go back to a dry period with dry mid level conditions taking over.
But interesting that the GFS is wanting to bring in eventually some moisture from the area of disturbed wx NE of P.R. in a few days.

[gatorcane]

Yes, it does and if that pans out, would see some good convection firing across Southern FL yet again this weekend....much like you would see from a tropical wave in Aug-Sept.

i can tell you last night it "just looked" like late summer out there yesterday evening with E to SE winds at 15mph and huge anvils towering to the west...with low cumulus blowing in from the Atlantic....

[gatorcane]

Today looks like convection fired over central Florida and sw Florida. The inverted trough north of the leewards that may swing through early next week could really enhance the rain chances. Dew points have fallen some today at palm beach international, but still in the upper 60s.

[gatorcane]

This is from 91L...looking like summer-time out there with each passing day.....

.LONG TERM...
HIGH PRESSURE WILL SLOWLY MOVE OFF TO THE EAST OF SOUTH FLORIDA
DURING THE WEEKEND. AN EASTERLY FLOW WILL CONTINUE, HOWEVER, A
LITTLE BIT MORE MOISTURE WILL MOVE INTO THE AREA ON SUNDAY.
THEREFORE ISOLATED SHOWER ACTIVITY WILL BE POSSIBLE ALONG THE
EAST COAST SEA BREEZE. EARLY NEXT WEEK, MODELS CONTINUE TO SHOW AN
INVERTED TROUGH MOVING INTO THE AREA FROM THE SOUTHEAST. WITH
MOISTURE CONTINUING TO INCREASE, SCATTERED SHOWERS AND
THUNDERSTORMS COULD DEVELOP EACH DAY ESPECIALLY DURING THE EARLY
PORTION OF NEXT WEEK

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

[gatorcane]

Lots of afternoon thunderstorms blowing up across the peninsula today...and the past couple of days and looks like the next several days before it dries out some towards the end of the week.

It will be interesting to see when NWS declares the start of the rainy season. Definitely looks like it is ahead of schedule this year with a median start date of May 21st.

[Patrick99]

I notice that dewpoints are now well above 70 all over South Florida..not just scraping 70. Sea breeze convergence mentioned daily in Miami forecast discussions.

I'm getting the feeling that our next relief from hot, humid weather will be in November - I think it has started, and we are now socked in for the rest of the spring, summer and much of fall.

[Scorpion]

Nothing at all here. Barely a trace of rain the entire month.

[Patrick99]

Oops, looks like this front might actually pass and we get a small dewpoint reprieve this weekend. Should feel pretty good compared to what we've been having.