Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Tampa Bay Ruskin Florida
320 am EST Wednesday Nov 25 2015
Short term (today and thursday)...
08z water vapor imagery illustrates a potent vorticity maximum digging
southward over the Pacific northwest/Oregon with shortwave energy
streaming over Arizona/Utah and the southern rockies this morning.
Surface temperatures range from around 50 degrees over the Panhandle of
Florida to around 70 over Southeast Florida and the Keys. Near and
above normal temperatures return to the area today and persist
through the remainder of the week. Marine winds will be the
element of interest through the week with a tight gradient in
place for mariners.
Meanwhile an 80-90 knots jet streak remains situated in a zonal flow
from Baja California California eastward across central Texas and across the
north- central Gulf of Mexico and over much of the Florida
Peninsula. As a result of the aforementioned features a swath of
middle and upper level moisture will continue to push across the
eastern Gulf this morning with infrared satellite trends
suggesting much of the middle- upper cloudiness will exit the area by
Low-level flow continues out of the east/northeast due to
a large and elongated area of surface high pressure situated over
much of the eastern U.S. High stratocumulus continues to translate
to the west within the low-level flow across the peninsula. NAM
and WRF-arw high res output appears to be more aggressive in
steepening moisture profiles and producing isolated showers this
afternoon. Will lean toward a blend of gfs20/ECMWF/sref output
with scattered/pcloudy stratocumulus passing from east to west today
with patchy broken/psunny conditions. Would not rule out a brief
sprinkle over far eastern counties of Polk and Highlands closer to
the moister profiles. Otherwise cap in place with dry middle-level
air above should preclude development over much of the western
forecast area toward the coast. Similar pattern in place for
Long term (thursday night - tuesday)...
an amplified blocking upper air pattern will persist across the
Continental U.S. Through the upcoming weekend as a Rex block out west keeps a
closed low quasi-stationary over the Great Basin within a positively
tilted upper level trough over the western U.S. And northern plains.
Downstream from the upper trough upper level ridging will persist
over the Gulf and Florida while a broad upper level low and weak
surface reflection over the eastern Bahamas at the start of the
period sinks south southwest toward eastern Cuba through the
upcoming weekend. At the surface high pressure will persist along
the eastern Seaboard with a tight pressure gradient maintaining a
breezy northeast to easterly wind flow across the region. Similar to
yesterday a slow increase in low level moisture within the low level
northeast to east flow will support a fair amount of cumulus/strato-cu
clouds across the forecast area each day...but dry subsident middle
level air should keep rain out of the forecast with dry conditions
and moderating temperatures expected.
During early next week the blocking pattern out west will break down
with the flow becoming more progressive with the closed low out west
moving east to the Great Lakes region...with a zonal flow aloft and
weaker surface high pressure along the eastern Seaboard supporting a
weaker easterly flow across the region. Adequate low level moisture
within the easterly flow combined with less suppression from weaker
ridging aloft will support slightly higher chances (pops 20 percent
at best) for a few showers across the forecast area on Monday and
Tuesday...especially over eastern most sections of the region each
afternoon...otherwise dry weather will continue.
Temperatures will remain some 5 to 10 degrees above normal through
the period with overnight lows in the lower 60s north...and middle to
upper 60s central and south...with daytime highs climbing to around
80 north...and lower 80s central and south.
VFR conditions will prevail at the terminals over the next 24
hours with east and northeast flow in place through the period.
Small Craft Advisory remains in place for the coastal and offshore
waters and will be extended through Friday morning as a ridge of
high pressure maintains a tight pressure gradient over the eastern
Gulf of Mexico and much of the Florida Peninsula. Brief periods
of below advisory conditions may occur...especially over the bays
and nearshore waters during the early afternoon hours...however
duration not expected to be long enough to justify
lowering/raising the advisory multiple times through the Holiday
period which could result in catching boaters off guard in a brief
no fire weather concerns are expected through the period. East and
northeast flow will prevail with warming temperatures and
increasing low-level moisture each day through the remainder of
Preliminary point temps/pops...
tpa 78 64 81 65 / 10 10 10 10
fmy 81 64 82 64 / 10 10 10 10
gif 77 62 79 62 / 10 10 10 10
srq 80 64 82 65 / 0 0 10 10
bkv 77 60 80 59 / 0 10 10 10
spg 77 66 80 66 / 10 10 10 10
Florida...Beach hazards statement through this evening for coastal
Charlotte-coastal Manatee-coastal Sarasota.
Gulf waters...Small Craft Advisory until 4 am EST Friday for coastal
waters from Bonita Beach to Englewood Florida out 20 nm-
coastal waters from Englewood to Tarpon Springs Florida
out 20 nm-coastal waters from Tarpon Springs to
Suwannee River Florida out 20 nm-waters from Bonita Beach
to Englewood Florida out 20 to 60 nm-waters from Englewood
to Tarpon Springs Florida out 20 to 60 nm-waters from
Tarpon Springs to Suwannee River Florida out 20 to 60 nm.
Short term/aviation/marine/fire weather...lamarre
long term/decision support...McMichael