Scientific Forecaster Discussion
fxus62 kmlb 220935
Area forecast discussion
National Weather Service Melbourne Florida
435 am EST Wed Nov 22 2017
..high rain chances for Thanksgiving day into Friday...
Currently...weak frontal boundary is shifting back south across the
area and is still producing some isolated showers near the cape.
However, should see this activity end over land areas before dawn.
Hrrr/local WRF guidance indicating greatest coverage of stratus and
fog will transition southward with this boundary through early
morning into Osceola/Okeechobee counties and the Treasure Coast
toward daybreak. There is still potential for locally dense fog
across the region, especially across aforementioned area through
early morning, with fog and stratus then burning off by late
Today-tonight...weak quasi-stationary front will remain across the
Florida Peninsula today. Area will be in a bit of a lull between short wave
that has exited well northeast of the area, and next approaching
disturbance ahead of developing short wave trough over the Gulf. Models
indicate a decrease in overall moisture with precipitable water values around 1.2-
1.3 inches, and MOS pops as well as hrrr/local WRF guidance all
indicate conditions will be mostly dry today. Best chance for
isolated showers look to exist across inland areas along a weak sea
breeze that will push inland this afternoon. Have therefore limited
rain chances to 20 percent for locations west of I-95. Some weak
instability will exist across the area as temperatures warm into the
upper 70s to low 80s this afternoon, but thunderstorm chances are
too low to mention.
Front begins to shift back north across the area into tonight as mid
level trough induces a weak low along the boundary, across the
eastern Gulf. Moisture gradually increases with east/southeast flow
strengthening overnight. This should allow for isolated to scattered
onshore moving showers along the coast, and additional shower
development from weak low level convergence along the northward
moving front. Thunderstorm potential continues to remain low
overnight, but could see isolated storms push into Lake County near
the front closer to daybreak. Fog potential looks low with
increasing boundary layer winds, but developing stratus will be
Thu-Fri...a slow moving upper trough over the Gulf of Mexico will
slowly translate east across Florida and weaken by Fri night. At the
surface, low pressure along the old frontal boundary over the
eastern Gulf will eventually push across cent Florida on Friday and
both GFS and European model (ecmwf) agree with this scenario. Low pressure moving
out of the Gulf and across Florida always gets our attention for severe
weather potential. In this case, considerable clouds will limit
heating/instability and wind fields are not very strong.
Nonetheless, temps aloft will be cold (-11c Thu and -13c Fri at
500mb) so cannot rule out a few strong storms. Have increased
rain chances for both Thanksgiving day and Friday with 70-80
percent Thu and 60-70 percent Fri.
Sat-Tue...cooler and drier airmass will overspread the area this
weekend on northwest flow as high pressure builds southeast from the
upper plains. Highs in the low to mid 70s thru Monday with lows
in the low to mid 50s Sunday morning with some upper 40s Monday
morning esp north of I 4. There may be some isolated coastal
showers that cross the coast Mon-Tue as flow veers out of the
Aviation...IFR/MVFR conditions in stratus and patchy/areas of fog
will be favored over interior taf locations and across the Treasure
Coast through early this morning. Should then see improving
conditions to VFR by late morning as fog lifts and Burns off from
daytime heating. Rain chances will remain low today through this
evening, and then increase overnight as moisture increases leading
to isolated to scattered showers developing overnight.
Increasing boundary layer winds look to preclude any fog mention for
tonight, but stratus will be possible producing IFR/MVFR cigs late
this evening into the overnight.
today-tonight...front shifting south across the waters this morning
will lead to a northerly flow up to 10-15 knots, becoming northeast
by late afternoon as boundary stalls. Winds will then continue to
veer to the east/southeast tonight as front shifts back northward, with wind
speeds remaining around 10-15 knots. Seas will range from 3-5 feet.
Thu-sun...low pressure will slowly move east/NE from the eastern Gulf
of Mexico Thu and across central Florida Friday. This will promote a
south to southeast wind flow over the local Atlantic waters of 10-15
knots. But the old boundary may drop back in to our northern
waters Friday and produce a wedge of north to northeast winds
along the Volusia coast. Regardless, there will be numerous
showers and embedded storms Thu-Fri. Once the low pressure pulls
east of the area Saturday, a drier northwest flow will overspread the
waters and build seas to 6 feet in the Gulf Stream this weekend.
Preliminary point temps/pops...
dab 75 63 74 63 / 10 40 70 60
mco 80 64 77 63 / 20 20 70 60
mlb 79 67 79 66 / 10 30 70 50
vrb 80 67 79 65 / 10 30 70 50
Lee 79 63 74 62 / 20 30 70 60
sfb 79 63 76 63 / 10 30 70 60
orl 80 64 77 63 / 20 20 70 60
fpr 80 66 80 64 / 10 30 70 50