Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Melbourne Florida
330 am EDT Friday may 22 2015
..poor boating/hazardous beach conditions for Holiday weekend...
..Rain coverage still looks low...
Current...weak frontal boundary across north central Florida
sinking southward this morning. This feature will lie across the
I-4 corridor around sunrise. Skies mostly clear early this morning
with some leftover cloud debris thinning around Lake Okeechobee
from the previous evenings convection. Mild temperature/dewpoint
readings in the 70s areawide. West/southwest surface winds out
ahead of the front are fairly light.
Today-tonight...the weak front will continue to slide southward
towards south-central Florida through the day. Winds will veer to
the northwest then north this morning behind the boundary...finally
to north-northeast in the afternoon...but earlier near the coast. The onset of
the East Coast sea breeze should be earlier than the previous day as
winds veer behind the front and the boundary will make further
penetration inland. Highest precipitable water values will be found
in vicinity of the boundary with forecast values approaching 1.80
inches later in the afternoon southward towards the Treasure
Coast/Okeechobee County. 500 mb temperatures will be around
Areas southward from Orlando will have the greatest chances for deep
convection this afternoon/evening. Will keep a slight threat for
showers/storms near Orlando. Will go with 30 to 40 percent probability of precipitation
southward from here across ecfl. Generally the main threats with
afternoon/evening convection will be frequent lightning strikes...locally
heavy downpours...gusty winds of 45 to 50 miles per hour and small hail. An
isolated severe storm is not out of the question with hail to
quarter size and winds to around 60 miles per hour. Local ponding of water on
roadways will be a hazard for heavier cells. Storm steering flow
will be out of the west-northwest/northwest at 5-10 miles per hour. Showers/storms will gradually
dissipate through late evening southward with cloud debris thinning
through the night.
Afternoon highs in the M/u 80s Volusia coast...u80s to near 90
degrees further southward down the coast with l/M 90s again into the
interior. Overnight lows generally in the u60s/l70s.
Sat-Mon...a transition to an easterly flow regime will start Sat as
high pressure bridges dissipating frontal boundary vicinity east
central Florida. Middle level anticyclone is forecast to build over
North Florida and deepen the onshore flow. Some higher moisture
will linger from the front on Sat...then deep layer ridging will
decrease moisture while temperatures aloft steadily warm.
This will cause highest probability of precipitation and main storm chances to shift inland
and to the west side of the peninsula through the period. 00z GFS
MOS values were 20 percent inland and 10-20 percent along the
coast...so will follow decreasing consensus pop trend with maximum of
30 percent inland and 20 percent coast. Main coastal chances
should be night/morning...but with quite low probability of precipitation...will not carry
overnight probability of precipitation over land.
The onshore flow will gradually temper maximum temperatures at the coast to
the middle 80s...and even inland with highs around 90 to the lower
90s. Overnight low will be very mild in the Lower/Middle 70s.
Tue-Fri...little change with the onshore wind flow regime...though
middle level ridge and surface high pressure are forecast to weaken by
late week. Deep layer moisture will remain limited and the GFS shows
a few ribbons of very dry air advecting westward across the
Atlantic and into the local area. This will keep probability of precipitation low...so no
real/true onset of the wet season is evident for east central
Aviation...weak boundary will slide southward across ecfl this
morning/afternoon. Winds will veer northwest/north behind this feature and
eventually north-northeast into the afternoon. Onset of ecsb should be earlier
than the previous day and it will penetrate further inland. Deeper
moisture/heating southward from kmco where greatest afternoon/evening
storm potential will be. Tempo MVFR ceilings/visibilities in vicinity of shra/tsra.
today-tonight...weak frontal boundary will slip down the
coastal waters this morning/afternoon. SW winds will veer northwest/north
behind this feature...eventually north-northeast through the afternoon...NE this
evening/overnight. Wind speeds may approach 10-15 kts north of
Sebastian Inlet...lighter southward. Seas 2-3 feet today building up
to around 4 feet tonight away from the coast/cape northward. Late
afternoon/evening storms could push off of the Treasure Coast. Winds/seas
locally higher in vicinity of storms.
Holiday weekend-Tue...quite strong high pressure will build to
the middle Atlantic coast Sat then seaward through early next week
with an axis extending into the southeast states. Forecast models
show about a 4 mb gradient along the Florida East Coast which
translates to about a 15 knot onshore flow. The GFS shows a few
periods of 20 knots offshore. Conditions for small craft operation
will be poor and expect that exercise caution statements will be
necessary Sat night into Memorial Day.
Preliminary point temps/pops...
dab 87 72 85 73 / 10 10 20 10
mco 92 73 91 72 / 20 20 30 10
mlb 88 74 86 76 / 30 30 20 10
vrb 89 72 87 74 / 30 30 20 10
Lee 91 72 89 73 / 10 10 20 10
sfb 92 73 88 72 / 20 20 20 10
orl 91 74 88 73 / 20 20 30 10
fpr 89 71 87 74 / 30 30 20 10