Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Miami Florida
234 PM EDT Wednesday may 27 2015
The high risk of rip currents continues for the Atlantic
The dry air that was forecast to arrive to South Florida is
already here. This is evident from the 12z sounding from this
morning. A very dry layer extends from 850 mb to 500 mb.
Relatively steep lapse rates between 500 and 700 mb are also
present. However, without sufficient moisture these steep lapse
rates will have no impact to the weather today. The steep lapse
rates (above 6c/km) are associated with southerly flow in the middle
levels, as the air is rotating around the middle level ridge of high
pressure ahead the trough of low pressure in the middle sections
of the country. A large surface high is located in the Atlantic
Ocean between latitudes 35 and 40. This high pressure is extending
over the western Atlantic generating a long fetch of easterly
winds in the Atlantic. Today, the atmosphere has dried out
sufficiently that even the line of isolated showers that has been
present for the last several days has not developed. A few
convergence lines from the Bahamas are also present. Although the
atmosphere is drier today than yesterday, there is still a
potential for some waterspouts to develop over the Atlantic
waters, especially associated with these convergence lines.
As the very dry air remains in place over the area with precipitable water
values still between around 1 inch. This forecast precipitable water value is
still near the minimum precipitable water values of 0.90 to 0.95 inches for this
time of year. Therefore...the weather will remain dry over South
Florida on Thursday.
The trough of low pressure will continue to move east this weekend
into the Middle Atlantic States as the high shift a little bit south.
This will keep an easterly wind flow over South Florida this
weekend and allow for more tropical moisture to work into the
area. Therefore...the probability of precipitation over south fl0rida will increase to
chance category this weekend with the best coverage of showers and
thunderstorms over the interior and West Coast metropolitan areas.
Previous discussion... /issued 152 PM EDT Wednesday may 27 2015/
easterly winds around 15 knots will continue through the afternoon
hours. A band of streamer showers has developed off Grand
Bahama. The band should remain south of kpbi and kfxe. Other light
showers were across the Atlantic waters...but these should remain
south of the taf sites. Waterspouts may be possible with this
activity. A weak sea breeze may develop at kapf this
afternoon...and showers may get near the taf site through the
early evening. Winds will diminish to around 10 knots after
midnight and then increase again in the morning to near 15 knots.
Mainly VFR conditions will prevail...but brief MVFR ceilings around
3 kft are possible.
Previous discussion... /issued 939 am EDT Wednesday may 27 2015/
high pressure keeping the easterly flow across the region this
morning. Today, the atmosphere has dried out sufficiently that
even the line of isolated showers that has been present for the
last several days has not developed. Between today and tomorrow,
conditions will be dry, with some of the interior areas having the
potential to drop below 35 percent relative humidity in the afternoon. Together
with breezy conditions expected, it may raise some fire weather
concerns, especially with on going fires in the interior of the
Preliminary point temps/pops...
West Palm Beach 73 87 73 87 / 10 10 10 20
Fort Lauderdale 75 86 75 86 / 10 10 10 20
Miami 74 87 74 87 / 10 10 10 20
Naples 71 90 70 90 / 10 10 10 30
Florida...high rip current risk through late tonight for flz168-172-173.