Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/29/18
Area Forecast Discussion
National Weather Service Boise ID
823 PM MDT Fri Sep 28 2018
.DISCUSSION...Thin cirrus clouds and a layer of smoke aloft have
increased across the area this evening. The smoke originated from
wild fires in southwestern Oregon and does not seem to be making
it to the surface. There haven`t been any observed reductions in
surface visibilities across southeastern Oregon or southwestern
Idaho. The latest runs of the experimental HRRR smoke model show
this layer of smoke becoming thinner and moving north of the area
tomorrow. Meanwhile, in the remote central mountains of Idaho,
the Prospect Fire produced a large smoke plume that primarily
affected wilderness areas today. Some of the smoke from the
Prospect fire could drain into the Idaho 21 corridor above Lowman,
Idaho tonight. The forecast remains on track for increasing
clouds tomorrow afternoon with a chance of rain tomorrow night
in the the northern portion of the forecast area.
.AVIATION...VFR. Smoke layers aloft. Surface winds light and
variable. Winds aloft near 10K feet MSL southwest 15 to 30 kts.
Weekend Outlook...High and mid level clouds increasing from the west
on Saturday as an upper level trough approaches. Isolated showers
and thunderstorms eastern Oregon Saturday evening. Scattered showers
Baker County Oregon and the central Idaho mountains late Saturday
night through Sunday. Isolated afternoon thunderstorms.
SHORT TERM...Tonight through Monday...Cut off low, currently off
the Northern California Coast, will weaken and drift across the
forecast area Saturday Night and Sunday. Best chances for
precipitation will be at higher elevations of Eastern Oregon
Saturday Night, and higher elevations of Southwest Idaho on
Sunday. Valley locations will see little, if any, precip. Main
change will be a drop in temperatures for Sunday, with afternoon
temperatures 5 to 10 degrees below normal. Temperatures recover
fairly quickly back to normal by Monday afternoon, as a short-
wave ridge moves across, ahead of the next trough approaching for
Tuesday and Wednesday.
LONG TERM...Monday night through Friday...An upper level trough
will move east across the Pacific Northwest Tuesday into Wednesday
bringing a slight chance of precipitation. This will keep the large
upper level low with associated moisture from the Hurricane Rosa
well south of the forecast area. Another weaker trough follows
for Wednesday night into Thursday for a slight chance of
precipitation across the higher terrain. After that trough exits
to our south a strong upper ridge moves inland from the north
Pacific that should bring dry and warmer weather Friday and
beyond. Temperatures will remain below normal through at least
PREV SHORT TERM...TB
PREV LONG TERM....JS/JS
Area Forecast Discussion
National Weather Service Charleston SC
932 PM EDT Fri Sep 28 2018
A weak cold front will slowly drop through the area this
weekend, followed by high pressure for much of next week.
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
GOES-E low and mid-level water vapor channels show a modest
shortwave moving into southwest Georgia late this evening. This
feature is on target to cross the region early Saturday as a
weak cold front meanders in from the west. This should help
spark the redevelopment of isolated to scattered showers/tstms
overnight, especially north of the I-16 corridor. RAP and H3R
consensus favors the greatest coverage occurring over interior
Southeast South Carolina (closer to the surface front) as well
as Charleston County where guidance continues to support the
formation of a weak land breeze circulation which could serve
as yet another source of low-level convergence. Adjusted hourly
pops slightly per going short term model trends, increasing
pops across interior Southeast South Carolina into the 40%
As clouds thicken, expect terminal falls to level out/slow
after midnight. Opted to nudge overnight lows up a degree or two
for many locations using the 28/11z H3R thermal field as a
rough proxy for the low temperature forecast.
.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
Saturday: A slow moving frontal zone hosting a band of deeper
moisture is forecast to sag across the forecast area with highest
PWATs progged north of I-16 in GA, encompassing most of southern
South Carolina and GA areas along the Savannah River. Isolated to
scattered convective rains may develop after mid morning across the
region, however the best chances for showers and tstms should occur
during the afternoon and evening hours. During this time period,
moisture convergence and depth, along with weak upper difluence all
appear to coincide after convective temps are reached. A few storms
could produce locally heavy downpours but wet profiles and marginal
mid level instability suggest little to no potential for severe
weather. We maintained likely POPs most areas along with highs from
the mid 80s north to around 90 degrees closer to the Altamaha River.
Sunday and Monday: Surface high pressure will build north and
eventually northeast of the forecast area, while mid and upper
level ridging expands north and blankets the southeast coast. On
Sunday, deeper moisture will reside over Southeast GA while somewhat
drier mid level air advects into northern SC zones later in the day.
POPs range from likely along and south of I-16 to about 30 percent
near Lake Moultrie in Berkeley County. By Monday, deeper moisture
should be confined to far south GA, with higher POPs to the south of
I-16. Subsidence will likely keep the Charleston Tri-County region
mainly dry Monday afternoon. Highs should be close to climo values
given the onshore synoptic flow.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
A large, deep layered ridge will affect the local weather
Monday night through Friday. PoPs will be minimal while temps
again rise back into the upper 80s which is well above-normal
for early October.
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
VFR. Could see tstms near the KCHS terminal after 09z as a land
breeze circulation could help concentrate activity there, but
latest data suggest this activity will remain east of the
terminal. Uncertainties with respect to convective
timing/coverage tomorrow afternoon necessitates taking a
conservative approach this far out, thus no mention will be
included in the 00z cycle.
Extended Aviation Outlook: Increasing chances for convection-
related flight restrictions Saturday afternoon through Sunday as
a front drops through the area. There is a potential for areas of
low clouds several hours around daybreak Sunday and Monday mornings.
Tonight: South winds 10 kt will veer to the west and southwest
overnight and diminish. Variable winds are likely by daybreak
for much of the local marine areas. Seas will average 2-3 ft
nearshore waters and 3-4 ft offshore waters.
Saturday through Wednesday: Light and variable flow along a
slowly moving frontal zone on Saturday will turn northeast and
onshore Sunday, then persisting into much of next week. Wedging
high pressure will build in from the north Saturday night
through Monday with strengthening northeast winds and building
seas expected. Small Craft Advisory conditions are possible over
the Charleston nearshore waters Sunday night, though much
greater potential exists over the offshore GA waters due to 6+
ft seas. In fact, SCA conditions expected to persist through
much of next week across the outer GA waters due to persistent
onshore flow and potential swell energy from post- tropical
cyclone Leslie well offshore.
Rip Currents: Distant Subtropical Storm Leslie could send long
period swell to our beaches later this weekend into next week.
This swell could produce an enhanced risk for rip currents.
An increase in onshore flow and building swells may result in
high tides approaching shallow coastal flooding criteria Sunday
and Monday along coastal SC and particularly in Downtown
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
859 PM CDT Fri Sep 28 2018
.DISCUSSION...Convection has decreased considerably with loss of
heating this evening with only very isolated light showers in the
area. 00Z CRP sounding showed a relatively drier and subsident
layer between 800 and 600 mbs. Will decrease PoPs slightly for
this evening to slight chance across the northern counties. Will
keep low end chance PoPs for the western Brush Country as HRRR
shows activity south of Falcon Reservoir could move north toward
the area. MSAS analysis shows low level convergence increasing
along the coast. With deep moisture in place, could see scattered
convection redevelop over the coastal plains before midnight. No
changes were made to the forecast after midnight with PoPs ramping
up to likely for the coastal plains and coastal waters. Low level
convergence will continue to strengthen near the coastal trough
and increasing upper level divergent flow will occur as a 25h jet
streak moves into south central Texas, this will lead to
atmospheric lift increasing with high resolution models showing
convection blossoming during the overnight hours. Locally heavy
rain will be possible along the coast.
.PREVIOUS DISCUSSION... /Issued 653 PM CDT Fri Sep 28 2018/
DISCUSSION...See Aviation section for 00Z TAFs.
AVIATION...Isolated showers will be possible for a few more hours
this evening across the region. Latest HRRR and 12Z HREF depicted
the convective activity will wane for the rest of the evening
hours. Expect VFR conditions for this evening except for MVFR
ceilings developing along the coast by 04Z. Otherwise, region will
be under extensive mid level cloud deck. Convection will increase
overnight along the coast in region of higher low level
convergence near a coastal trough, assisted by an upper level jet
streak moving across south-central Texas. MVFR vsbys/ceilings will
occur within convection that will develop around 09Z and spread
inland through the morning hours. IFR vsbys will be possible with
heavy rain in thunderstorms. Activity should reach LRD area by
late morning and continue into the afternoon. Coverage of the
convection may decrease some by the afternoon over the coastal
plains but will keep TEMPO group for coastal sites until mid
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 74 83 74 85 76 / 70 80 50 70 40
Victoria 72 83 71 84 73 / 60 80 30 70 30
Laredo 73 85 72 86 73 / 40 50 30 50 20
Alice 72 84 72 86 74 / 60 70 50 60 30
Rockport 75 84 75 85 76 / 70 80 50 70 40
Cotulla 72 86 71 86 73 / 40 50 30 50 30
Kingsville 74 84 74 86 75 / 60 80 50 60 30
Navy Corpus 77 84 78 85 79 / 70 80 50 70 40
East Central Florida Forecast Discussion
National Weather Service Melbourne FL
936 PM EDT Fri Sep 28 2018
...High Risk of Dangerous Rip Currents Into This Weekend...
Currently-Tonight...Showers and a few storms resulting from late
boundary collisions have just about dissipated inland. Data from the
Air Force profilers at XMR have shown continuation of deep onshore
flow with winds around 10 kt. This onshore flow will potentially
contain a few showers mainly south of Sebastian Inlet into Saturday
morning. HRRR guidance is not too enthusiastic however on
development over the adjacent Atlc waters overnight. Will keep a 20
pct or less mention for the S Brevard coast to Jupiter for psbl
activity. Expect temperatures falling into the mid to Upr 70s by
Sat-Sun...High pressure ridge north of the area will maintain an
easterly flow across central Florida into the weekend. Drier mid
level air and lingering ridge aloft will keep rain chances out of
the forecast for much of the area Saturday. A slight chance of
showers and storms will mainly exist across the Treasure Coast
and Okeechobee County where greater moisture will reside. Then
into Sunday, moisture increases across the area in the onshore
flow, with PoPs rising, but still remaining below normal. Rain
chances will range from 20 percent across northern portions of
east central Florida, up to around 30 percent south of a line from
Orlando to the Cape. It will remain quite hot into the weekend
with highs in the upper 80s to around 90 degrees along the coast
to low to mid 90s over the interior.
Hazardous beach conditions will exist along the coast of east
central Florida through the weekend, as building long period
swells will generate rough surf and a high risk of strong and
dangerous rip currents each day.
VFR conditions overnight. East to southeast winds 5 to 10 knots,
becoming light and variable inland overnight.
Tonight...E/SE winds up to 10-15 knots will exist over the coastal
waters into tonight, with seas ranging from 3-5 feet.
Sat-Sun...A long period swell from the northeast will build and
reach our coastal waters, starting on Saturday. As these build,
the significant wave height will increase as well and will
correlate with a period between 16 and 20 seconds. By Sunday, seas
will build up to 7 feet offshore with the influence of increasing
winds and swells reaching east central Florida waters. Advisories
for mariners and beach goers will be necessary starting this
weekend and extending into most of the following week.