Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/29/19
Area Forecast Discussion
National Weather Service Bismarck ND
923 PM CDT Wed Aug 28 2019
.UPDATE...
Issued at 923 PM CDT Wed Aug 28 2019
As of 02 UTC, the surface cold front is roughly along a Minot to
Watford City line and is on track to reach roughly the Bismarck
to Hettinger corridor by 06 UTC. North winds have gusted to ~30 kt
for about an hour behind the frontal passage in northwestern ND,
as expected. Recent HRRR guidance captures both the timing and
magnitude of this relatively brief increase in winds that`s being
driven by low-level cold air advection and isallobaric forcing in
the immediate wake of the frontal zone, so we relied on its output
to make minor changes to hourly wind forecasts through about 07
UTC with this update cycle. We still believe low-level decoupling
and related increases in boundary layer static stability prior to
frontal passage will reduce wind potential with both time and
southeastward extent. Otherwise, radar imagery reveals high-based,
post-frontal showers in the north and that activity was simply
extrapolated southeast toward Harvey and Carrington before exiting
the area by about 06 UTC. Midlevel lapse rates are only around 6
C/km, and combined with lackluster tropospheric moisture content
as exemplified by PWATs of 1.00 inches or less, bouyancy appears
too limited for lightning production with this activity.
UPDATE Issued at 610 PM CDT Wed Aug 28 2019
Western and central ND remains in the pre-frontal warm sector as
of 23 UTC, with the surface cold frontal zone near a Brandon, MB,
to Estevan, SK, line at this hour. Modest pressure rises on the
order of 1-2 mb/3 hour are being observed behind the front, but
observed surface winds sustained in the 15-20 kt range have been
common with frontal passage. Given that and the front`s expected
progression through northwestern ND by 03 UTC -- close enough to
the diurnal heating cycle that the boundary layer will still be
relatively well-mixed -- we increased wind speeds into that range
in that area with this update. Further southeast, the boundary
layer will have more time to decouple prior to frontal passage,
and low-level cold air advection behind the front is forecast to
diminish with time per guidance including recent RAP cycles. Thus,
we gradually weighted the wind forecast back toward the lower-
speed multi-model consensus after 06 UTC. Otherwise, only minor
changes were made to reflect observed trends and near-term bias-
corrected NBM guidance through the evening with this update.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 203 PM CDT Wed Aug 28 2019
Small precipitation chances, breezy and cooler conditions
highlight the short term forecast.
Low pressure currently over southern Saskatchewan will track
southeast across southern Manitoba tonight, dragging a cold front
through western and central ND. There have been some showers
across southern Saskatchewan today with a shower currently in
Regina. Latest iterations of CAMS have been pretty consistent in
bringing and area of showers across the northern tier counties
this evening, associated with the frontal boundary. We introduced
some small pops utilizing a blend of short term guidance. QPF is
expected to be very light with most areas seeing only trace
amounts if anything, given the dry lower atmosphere. Expect less
clouds and no precipitation central and south tonight, but there
may be a temporary spike in winds across the forecast area behind
the cold front, as it sweeps southeast across the state.
Winds will remain breezy along and east of the Highway 83 corridor
through the day. After morning lows in the mid 40s to mid 50s,
look for cool afternoon highs Thursday ranging from the mid 60s
north to lower 70s south.
.LONG TERM...(Thursday night through Wednesday)
Issued at 203 PM CDT Wed Aug 28 2019
Generally quiet weather is expected early in the weekend with only
hit and miss showers Friday and Saturday. High temperatures are
expected to be in the mid 60s to mid 70s each day.
Sunday and Monday we see a building upper ridge trying to push
into the High Plains, this should bring increasing temperatures,
especially west. In addition, there will be a better chance of
thunderstorms with daytime heating ahead of a Northern High Plains
lee side trough, combined with shortwave energy propagating
through the mean upper ridge.
A quick cooldown Tuesday with dry conditions behind a northern
stream shortwave. A stronger upper level system tries working it`s
way through through the mean ridge, possibly bringing a better
chance of thunderstorms by the end of the extended period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 923 PM CDT Wed Aug 28 2019
VFR conditions will prevail through the 00 UTC TAF cycle. A cold
front will move southeast across western and central ND tonight,
with a shift to north-northwest winds, which will gust to around
25 kt for an hour or two behind the frontal passage in parts of
the area. Low-level wind shear remains likely at KJMS ahead of
the front for a few hours either side of 06 UTC as light southerly
surface winds continue while westerly winds aloft strengthen.
Otherwise, only a period of VFR midlevel clouds and isolated to
scattered, high-based showers are expected behind the front in
the north this evening.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CJS
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...CJS
Area Forecast Discussion
National Weather Service Burlington VT
737 PM EDT Wed Aug 28 2019
.SYNOPSIS...
A line of showers associated with a frontal boundary will
continue to move eastward into western New England this evening.
The line will exit Vermont shortly after midnight, followed by brief
high pressure building in which will keep the area dry through
Thursday night. A weak front will move through Friday and bring
some light showers. High pressure follows this system on
Saturday bringing cooler and drier weather to the region to
start the holiday weekend.
&&
.NEAR TERM /THROUGH THURSDAY NIGHT/...
As of 730 PM EDT Wednesday...The forecast remains largely on
track as we progress into the evening hours. I did slow timing
of departing cloud cover slightly based off latest sat/ob trends
and also introduced some patchy post-frontal fog overnight,
mainly across northern NY in line with most recent NAM 3km vsby
output. Fog won`t be widespread, especially given stronger flow
aloft associated with approaching upper trough advects into the
area later tonight, but the idea that some may be floating
around still looks reasonable at this point. Have a great
evening.
Prior discussion...
A frontal boundary is progressing eastward through the region
this afternoon, resulting in a line of light to moderate showers
moving through. Ahead of the boundary, mesoanalysis showing a
narrow moisture axis extending northward into Canada (PWATs
around 1.6 inches), which is supporting some moderate showers.
As the band progresses eastward into central and eastern Vermont
later this afternoon into this evening, will see a brief uptick
in precipitation rates and amounts as the front encounters an
increasingly moist environment thanks to a weak coastal New
England low. This low pressure system will direct onshore
southeasterly flow towards Maine, New Hampshire, and somewhat
extending into eastern Vermont. The best moisture and heaviest
rainfall amounts this evening/overnight will stay well to the
south and east of our forecast area, but the coastal low
pressure system will work in tandem with the aforementioned
frontal boundary to bring up to a half inch of precipitation to
central and eastern Vermont this evening.
There will be a fairly well-defined back edge to the rain
showers that will bring a quick shift to drier weather overnight.
In the wake of the showers, low-level moisture will linger
overnight, which will result in some persisting low stratus
clouds and areas of mist developing. Overnight lows will be in
the upper 50s to low 60s. Brief ridge of high pressure will
build in during the day Thursday, so mainly dry weather
expected. Once the low clouds lift during the morning hours,
we`ll see a mix of sun and some scattered fair weather cumulus
clouds developing for the remainder of the day. High
temperatures will be in the mid to upper 70s, with relatively
low humidity values.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
As of 323 PM EDT Wednesday...Brief surface ridge over the area
Thursday night moves out Friday morning in advance of an approaching
upper trough and attending cold front which will skirt along
northern portions of the forecast area through the day. In general,
the best dynamics stay north of the international border and overall
deep moisture weakens as the front shifts over the area, so while
some showers are possible, the day certainly won`t be a washout and
precip should end by the afternoon`s high pressure over the Great
Lakes begins to shift east. While the front will be dynamically
weak, it will be thermally strong and usher in fall-like
temperatures for Friday night which will last into the weekend.
Highs ahead of the front on Friday will range through the 70s, with
lows Friday night falling into mid 40s to low 50s.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 323 PM EDT Wednesday...Weather for the Labor Day holiday
weekend begins about as good as you can get with high pressure
dominating for Saturday through much of Sunday. The result will be
generally sunny to partly cloudy skies but temps will be slightly
below normal with 850mb temps only around +5-8C supporting highs of
70-75 and lows in the 40s Saturday night. For Sunday afternoon
through Monday, models continue to trend towards more unsettled
weather as a shortwave trough traversing the midwest takes aim at
the mid-Atlantic and central/southern New England. Still some
question whether the surface high stays strong enough to shunt the
precip further south, so have offered some mid- chance to low-likely
PoPs Sunday evening and night, with the highest chances being across
southern Vermont.
High pressure returns Monday night with drier weather expected for
Tuesday along with a return of more summer like temperatures as
highs rise into the mid 70s to around 80. This is due to increase
south/southwesterly flow ahead our next front which looks to renew
chances for showers Tuesday night and Wednesday.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Through 00Z Friday...Challenging with changeable flight
conditions expected at our taf sites overnight into early
Thursday morning. Radar shows a very slow moving broken line of
showers across the CPV into central VT, which should exit our
taf sites by 03z. Vis sat shows a window of clearing behind
occluded type boundary approaching the slv with light bl flow.
This clearing combined with saturated bl from today`s rainfall,
along with light winds should result in some fog/br with ifr
conditions likely at mss/slk and pbg. However, RAP and NAM3km
indicate a low level jet develops at 15 to 25 knots around 500
feet agl, which may result in more stratus than fog for our taf
sites overnight into Thursday morning. Have utilized tempo for
BTV with 2sm sct 200 feet btwn 08-11z and similar for Rutland.
Winds shift to the northwest on Thursday at 4 to 8 knots with
cumulus clouds developing in favorable upslope flow wind
component. Any lingering IFR at SLK/MSS should improve by 14z
with mainly vfr except intervals of mvfr cigs at mtn sites.
Outlook...
Thursday Night: VFR. NO SIG WX.
Friday: VFR. Slight chance SHRA.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. NO SIG WX.
Saturday Night: VFR. NO SIG WX.
Sunday: VFR. Slight chance SHRA.
Sunday Night: Mainly MVFR, with local IFR possible. Chance SHRA.
Labor Day: Mainly MVFR, with areas IFR possible. Chance SHRA.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...Duell
NEAR TERM...Duell/JMG
SHORT TERM...Lahiff
LONG TERM...Lahiff
AVIATION...Taber
Area Forecast Discussion
National Weather Service Dodge City KS
640 PM CDT Wed Aug 28 2019
...Updated Aviation section...
.UPDATE...
Issued at 551 PM CDT Wed Aug 28 2019
Update to increase/add near term low slight chance pops across
the south for later tonight/overnight reflecting what the HRRR and
the arw/nmm have been showing. Little to go on forcing wise
however a decent moisture advection signal is in place overnight
in the boundary layer, and isolated storms are already noted
across eastern Colorado into the Texas panhandle.
&&
.SHORT TERM...(This afternoon through Thursday)
Issued at 1141 AM CDT Wed Aug 28 2019
Quiet weather for the short term forecast under the influence of
surface high pressure and upper level ridging extending off the
Rockies giving way to northwest flow aloft and dry conditions.
Breezy south winds this afternoon 10-20 mph with temperatures
pushing into the mid to upper 80s with the increased warm low
level flow. Expect winds to ease after sunset and the few mid
level clouds to clear out due to radiational cooling. Morning low
temperatures heading into Thursday morning will be more mild in
the 60s as the low level moisture and humidity starts to filter
back in from the south ahead of the next storm system. Afternoon
high temperatures will push back into the 90s with south winds
picking up to 10-15 mph due to the increased daytime heating being
the main drive for the diurnal trend.
Changes come late Thursday as a shortwave pushes off the northern
Rockies dropping a frontal boundary through the high plains
bringing the first round of scattered rain showers and isolated
thunderstorms into the overnight through Friday morning. This
first round will see the best chance for any severe weather due to
the stronger daytime heating and instability with the moist Gulf
of Mexico flow in the low levels. However, capping looks to be the
main factor in storms making too far eastward out of Colorado
along a dryline. Any storms look to be under severe thresholds
east of Hwy 83 once the sun sets and the storms lose its juice.
QPF amounts look to be under an inch increasing the further east
as the next round for Friday afternoon and evening looks to be the
heaviest giving into the flooding concerns that will be discussed
more in depth for the long term forecast. Otherwise, the short
term will remain fairly quiet with dry and warming temperatures
expected with changes at the end of the period heading into the
long term.
.LONG TERM...(Thursday night through Wednesday)
Issued at 1243 PM CDT Wed Aug 28 2019
The start of the long term forecast will be quite active behind
the aforementioned frontal boundary as mentioned in the short term
discussion. Cloud cover will linger for much of the day on Friday
with some sun breaking out for far southwestern counties allowing
for afternoon highs to push into the low 90s but closer to 80 the
further north and east. Ongoing rain showers will linger for this
part of the CWA with the next big round later in the evening and
overnight into the start of the holiday weekend for Saturday. An
additional 2-3 inches east of Hwy 183 and less than an inch the
further west will come with this round associated with the
main upper level trough supporting the surface boundary. Flooding
will be the main concern for the start of the long term into the
weekend to include possible river stage concerns as well. The
models, though, have pulled back some on the QPF output where as
before there was 3 plus inches for much of the second tier of
eastern counties from Hays to Coldwater but now constrained to the
St. John area and eastward.
Ongoing storms and rain showers look extend into much of Saturday
lingering in the eastern counties even into the evening hours.
Mild temperatures in the 60s to start the weekend mornings and
afternoon highs pushing only into the upper 70s to low 80s due to
the ongoing precipitation and cloud cover. Expect more sun for
Sunday and into Labor Day with highs pushing back into the upper
80s to low 90s as ridging and surface high pressure builds back
into the high plains with the increased convergence aloft with the
aforementioned trough pushed further east into the Missouri River
Basin.
Expect quiet weather for the most part into the extended long term
through mid week with temperatures ranging from the 60s in the
morning to near 90 during the peak heating hours of the afternoon,
much near average for this time of year to start the month of
September. A minimal chance for precipitation for Wednesday with
a weak shortwave propagating across the region mainly looking more
to affect northern counties along the I-70 corridor but
confidence is low at this time due to being so far out and model
inconsistency at this point. For now, the main concern will be
for Friday and into Saturday with flash flooding and river
flooding concerns being the main focus in areas already so
saturated from the past week or so of heavy rainfall.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 638 PM CDT Wed Aug 28 2019
Little has changed for this latest TAF cycle. There is a very slight
chance convection could affect a terminal as far north as DDC,
however any showers/storms this evening and early overnight ought
to be brief and non-severe as well as quite isolated. Beyond this
evening - weak gradient will allow light south wind through
Friday afternoon, with best gust potential across central Kansas,
so we could see some gusts as high as 15 to 20 knots around Hays
to Dodge City.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 65 95 67 88 / 10 0 20 30
GCK 63 97 65 89 / 10 0 20 30
EHA 61 99 64 93 / 10 0 10 20
LBL 65 97 66 92 / 10 0 10 20
HYS 63 92 65 80 / 0 0 40 40
P28 67 94 69 87 / 30 20 20 30
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Russell
SHORT TERM...Lowe
LONG TERM...Lowe
AVIATION...Russell
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1046 PM CDT Wed Aug 28 2019
.Discussion...
Issued at 248 PM CDT WED AUG 28 2019
Primary forecast focus is on thunderstorm chances Thursday.
Another beautiful day across the region, as the surface ridge
remains centered over the Ozarks. Surface winds have begun to shift
more to the southwest and south, as the surface high continues to
slide east and southeast. In response, we`ll end up with a gradual
uptick in boundary layer warm air advection into Thursday; overnight
lows will only dip into the middle to upper 60s.
Into Thursday, with the surface ridge continuing to exit eastward,
southerly flow will continue to transport higher dew points, ahead
of an approaching surface front, into the low/mid-Missouri Valley.
At present, it appears most short to mid-range guidance is likely
over doing dew points 2 to 5 degrees F, given 18z surface analysis
has 70 dew points still south of I-40 in Oklahoma. With this in
mind, it would be best to temper model derived instability tomorrow
afternoon. Regardless, confidence is increasing that storms will
develop along the front as it drops out of Iowa/easter Nebraska into
Missouri/eastern Kansas. Ahead of this boundary, a few runs of the
RAP suggest some pre-frontal convection, around midday, focused
along an axis of isentropic ascent is possible in eastern Kansas.
This development will hinge on available low/mid-level moisture.
Convection Thursday afternoon, along the front, will likely kick off
mid to late afternoon in southern Iowa, which will be preceded by
some likely morning rain/storms. Expect initial convection to
organize into a line or somewhat broken line as it pushes into
northern Missouri through the evening. Deep layer shear and
instability will be sufficient for a few strong to severe storms,
capable of pockets of damaging winds and possibly hail up to quarter
size.
Rain and storm chances will carry into Friday, as a short wave
trough moves through the region. With zonal flow aloft, the short
wave will be slow to exit east. This will result in off and on rain
chances through Friday and lingering through the day, Saturday.
&&
.Aviation...(For the 06Z TAFS through 06Z Thursday Night)
Issued at 1046 PM CDT WED AUG 28 2019
VFR conditions will dominate through much of the fcst period with
concerns mainly confined to the end of the fcst as shwrs/storms
approach from the north. Before then, winds will increase out of
the southwest after 15z with speeds of 10-15 kts expected. Towards
the latter half of the period, shwrs/storms are expected to track
south towards our area, with model indications suggesting
activity will move into the area during the 3-6z time frame. For
now, have only offered a VCTS mention in response to various
arrival times from latest model guidance.
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
MO...NONE.
&&
$$
Discussion...Kurtz
Aviation...32
Area Forecast Discussion
National Weather Service Gray ME
1144 PM EDT Wed Aug 28 2019
.SYNOPSIS...
A cold front will approach from the west tonight as moisture
from Tropical Storm Erin streams north. As this moisture
collides with the cold front, expect a period of heavy rainfall
tonight into the early morning hours, especially on the coastal
plain. High pressure builds in briefly behind the cold front
for Thursday with another frontal boundary ushering in cooler
and drier air Friday night and lasting through the weekend.
&&
.NEAR TERM /TONIGHT/...
1145PM UPDATE...
Made a few minor adjustments to update hourly precipitation
chances and temperatures. No significant change in forecast
thinking. Band of heavier rain is now developing along the New
Hampshire and southwest Maine coastline.
935PM...
Adjustments to forecast are mainly on timing of precip and I
did limit TSRA chance to just coastal areas based on current
conditions. Watching the area of convection that is currently
stretching from S central MA to ern Long Island, as this is
where the source of the heaviest rain will be over the next 6
hours across coastal areas of NH and ME. HRRR and RAP in fair
agreement, that some training may occur east of a line from
Seacoast NH NNE toward KAUG-KWVL, and again this remains in the
FFW area. Overall QPF is slightly lower, but could still
localized amounts of 2-3 inches, with 1-2" possible in 2-3
hours in this area through about 06-07Z. The next hour or two
should tell the story whether that band begins to form, and how
intense it is, as it will feature pre-cold front instability
interacting with coastal front.
625PM...
Have adjusted POPs to fine tune the timing and coverage of the
rain overnight. Also have lowered QPF somewhat, especially in
the FFW area, as thinking is that basin average amounts will
probably come 1-1.75" in these areas, and the higher amounts,
in the 2-3" range will be more localized. These areas are hard
to pinpoint exactly, but meso models do show some enhanced
forcing along the coastal front this evening, and then into the
SE upslope areas of the ME foothills midnight and shortly
thereafter, which is well covered by the current FFW. The model
trend is putting the best forcing and heaviest QPF along the
coastal this evening, so this will need to be watched for any
training or slow moving cells. Thinking is the greatest threat
for flooding along the SW ME coast and adjacent inland areas
will be thru around midnight, with the threat in mid-coast and
central lingering until 3-4 AM.
ORIGINAL DISCUSSION...
Northern New England is awaiting synoptic scale forcing
approaching from both the west and the south. To the west a NNE
to SSW oriented cold front was slowly moving through eastern New
York state. Showers and some stronger embedded convection was
moving northeast along the front. To our south a plume of
moisture associated with Tropical Storm Erin was impacting
Connecticut and Massachusetts and was poised to reach southern
NH later this afternoon. The airmass over the region is
characterized by high theta-e air with deep warm cloud depths.
Southerly winds and an increasing LLJ around 35 kts ahead of the
front will feed into a convergence zone along the front
supporting training of cells. Forcing for ascent will increase
aloft as heights continue to fall.
The interaction of these features will support efficient warm
rain processes normally indicative of heavy and even torrential
(2"/hour or more) rains overnight. Rainfall should spread into
southwest Maine this evening and arc northward with time
tonight, with isolated thunder over southern sections. The
heaviest rainfall should occur late tonight into the overnight
hours as the boundary slows as it nears the coast...generally in
the area delineated by the Flash Flood Watch. Model consensus
along with collaboration with the NERFC and SPC support totals
of 1-3" along the front with the possibility of up to 4" in
isolated areas. The Flash Flood Watch remains unchanged.
Overnight lows will be in the upper 50s to mid 60s.
&&
.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
Precipitation moves out quickly in the morning as a potent
short wave swings through. We remain in cyclonic flow aloft with
a narrow ridge of high pressure building in briefly through
Friday morning. The drier airmass will allow for sunny skies
over central and southern NH with partly cloudy skies elsewhere.
Highs should warm into the mid 70s north to lower 80s in the
typically warmer areas. Lows Thursday night will generally be in
the 50s areawide.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Ensemble and deterministic model solutions are in decent agreement
on the long wave pattern through early next week. The entire
forecast period consists of a broad low amplitude trough over much
of the northern third of the CONUS with the exception of the
Pacific northwest. With the mean jet position nearby or overhead
we`ll see quick day-to-day changes in sensible weather as a series
of impulses and weak surface systems traverse the area. In the
dailies...a cold front will cross the area with scattered
convection Friday night. High pressure follows for Saturday and
early Sunday. A weak system arrives with clouds and a more
widespread round of convection late Sunday into Monday.
&&
.AVIATION /04Z THURSDAY THROUGH MONDAY/...
Short Term...Moisture from offshore Tropical Storm Erin will
overspread the region and interact with a cold front, leading
to IFR conditions for southern New Hampshire and along the
coastal plain beginning this evening, and for all TAF sites
overnight. Expect low visibilities in +RA between 4-12Z
Thursday before improvement from west to east. There will be
some fog around during this time as well. A return to VFR
conditions is likely later Thursday morning as the cold front
pushes eastward.
Lightning...We may see isolated thunderstorms near PSM...CON...
and MHT tonight.
Long Term...
Fri PM...Sct MVFR in -shra/-tsra.
Sun PM - Mon...Areas of MVFR in SHRA/TSRA.
&&
.MARINE...
Short Term...Southeast onshore flow develops tonight but should
stay below advisory levels. Onshore winds don`t last long enough
to generate higher wave heights before a cold front arrives
early Thursday morning, shifting winds to the west. Seas
increase to 5 ft for the central and eastern far outer waters
late Thursday night into Friday however.
Long Term...
Fri PM - Sat...SCA`s possible outside the bays.
&&
.HYDROLOGY...
Deep tropical moisture will interact with several atmospheric
triggers to produce widespread heavy rainfall tonight into the
early morning hours on Thursday. A front will stall near the
coast and align perpendicular to the mean flow, allowing very
high PWAT air to pool along it. A flash flood watch is in effect
for southeastern NH and the foothills and coastal plain of
Maine. Although flash flood guidance values are on the high
side and we have been in a recent dry spell, any areas that see
multiple rainfalls (training cells) of heavy rainfall in a
short amount of time have the potential for localized flash
flooding.
&&
.TIDES/COASTAL FLOODING...
High astronomical tides will begin Friday and continue over the
weekend. While flooding is not expected, long-period swell
associated with Tropical Storm Erin combined with expected tide
levels may lead to splashover and nuisance flooding during the
Friday, Saturday, and Sunday late night high tides.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Flash Flood Watch until 8 AM EDT Thursday for MEZ012>014-
018>028.
NH...Flash Flood Watch until 8 AM EDT Thursday for NHZ010-012>014.
MARINE...None.
&&
$$
NEAR TERM UPDATE...Kimble
SHORT TERM...Hanes
LONG TERM...Schwibs
Area Forecast Discussion
National Weather Service Key West FL
947 PM EDT Wed Aug 28 2019
DISCUSSION...In the middle and upper levels(700-200 MB), latest
available satellite imagery overlaid with model streamline
analysis as of 900 pm, like 24 hours prior, depicts a complex
middle and upper level flow pattern over the Southeastern United
States including Florida and the Florida Keys, with the axis of a
east to west oriented ridge above 500 mb extending in the Central
Gulf from along 90W to across to across Central Florida thence
northeast to near 30N 75W. East of that feature, a (TUTT)
tropical upper tropospheric trough cell is migrating slowly
westward and is now located just north of the Dominican Republic
near 22N 70W. Of course, southeast of that feature is
strengthening Hurricane Dorian, which was located at 8 pm to be
at 19.2N 65.7W or about 60 miles NNE of San Juan, Puerto Rico.
At the surface and in the middle levels(Surface to 700 mb), latest
available marine and land surface observations and analysis as of
900 pm, details decoupled Tropical Depression #6 which at 5 pm was
located about 165 miles ESE of Cape Hatteras, NC. This system
trails a trough axis south southwestward into the Central Bahamas.
As was the case 24 hours ago, there is a near 1015 mb meso- hi
pressure center located over the SE Gulf of Mexico. Latest CIRA
data suggests deep moisture, typical at this time of year,
surrounds the Florida Keys with PWAT at 1.75 to 2.00 inches, but
rises to between 2.00 and 2.25 inches upstream of the Keys across
all of the Northern and Central Bahamas in association with
aforementioned approaching TUTT cell and the low level trough. The
evening sounding illustrated PWAT at about 1.80 inches with still
gentle to moderate northwest to north flow from off of the surface
up to 500 mb, then continuing to be light to gentle all the way to
150 mb.
.CURRENTLY...As of 900 pm, skies are partly cloudy across all of
the Florida Keys and surrounding waters. Radar still detects
isolated to widely scattered showers and isolated storms still
exist along boundaries, mainly concentrated attm across the
Eastern Florida Straits, but like last night, this was the
remnants of clusters of showers and storms that moved off the
Mainland from the seabreeze in the moist gentle to moderate
northwesterly flow. Temperatures across the islands remain in the
upper 80s with sticky dewpoints in the upper 70s. C-man stations
along the Florida Reef are still recording NW winds between 10 and
15 knots, but with gusts between 15 and 20 knots. Island sensors
are recording NW winds between 10 and 15 mph.
.SHORT TERM...Overnight and Thursday, as the trough over the
Bahamas continues to slide westward overnight towards the Keys, increasing
moisture upstream of the Keys and surrounding waters will work
its way westward, with PWAT rising to between 2.00 and 2.25
inches by 12Z. As such, HRRR and the Caribbean HRRR both agree
additional showers and storms will redevelop later tonight again
along boundaries upstream of both the Upper Florida Keys, as well
as over the Extreme Southeastern Gulf of Mexico upstream of both
the Middle and Lower Keys. The configuration of the ridge to our
southwest and the approaching surface/low level trough will
continue to allow for gentle to moderate winds this evening and
overnight and early Thursday morning. The confluent flow will
drive boundaries, showers and storms across the Keys and all
surrounding waters. As such, we are carrying 50% chances for 12
hour pops for scattered showers and storms, above the 35% climo
pops for the date.
&&
.MARINE...Gentle to moderate breezes will continue overnight and
Thursday morning. Winds and seas will be higher in and near some
of these showers and storms. Hurricane Dorian is expected to
track northwest overnight through Friday morning.
&&
.AVIATION...Mainly VFR conditions will prevail at the island
terminals for the next 24 hours, but there will be periods of
shower and thunderstorm activity near each terminal. For example,
convection will blossom over the Southeast Gulf after midnight and
then move to the southeast toward EYW and MTH during the late
night and morning hours. These showers should dissipate by mid-day
Thursday, and the overall trend is reflected with VCSH in the
TAFs. Then afternoon thunderstorms over the Everglades on Thu
afternoon will slide to the southwest toward the Middle and
possibly the Lower Keys during the late afternoon and early
evening.
&&
.TROPICAL...Now is the time to make sure you have a hurricane
plan. Now is the time to have your supplies ready. Do not wait
to make a plan and gather supplies when under increased stress.
Portions of the Florida Keys are presently inside the forecast
cone as of 900 pm. Remain up-to-date with the latest forecast
either through hurricanes.gov or weather.gov/key.
At 800 PM AST (0000 UTC), the eye of Hurricane Dorian was located
by an Air Force Reserve Unit Hurricane Hunter aircraft near latitude
19.2 North, longitude 65.7 West. Dorian is moving toward the
northwest near 13 mph (20 km/h), and this general motion is
expected to continue through Friday. On this track, Dorian should
move over the Atlantic well east of the southeastern and central
Bahamas on Thursday and Friday.
Looking ahead please consider these factors! (from CLR, previous
Forecaster Discussion) The expected NW to WNW turn by
strengthening Hurricane Dorian will take place Friday evening or
Saturday morning east of the Bahamas. This turn is critical. How
far west will the surface trough make it into the Gulf of Mexico?
How quickly will the subtropical ridge build to the north of
Dorian? Dorian`s eventual landfall location along the Florida east
coast will depend upon the timing and degree of WNW turn Friday
evening/Saturday morning. For now, the official track takes Dorian
into north-central Florida. The average error for the day 5
forecast point is nearly 200 miles, and Dorian is not an easy
forecast to resolve.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...None.
GM...None.
&&
$$
Public/Marine/Tropical...Futterman
Aviation/Nowcasts/Statements/Warnings....Haner
Social Media...SDR
Upper Air/Data Collection......DR/NB
Visit us on the web at weather.gov/key
Follow us on Facebook and Twitter at:
www.facebook.com/nwskeywest
www.twitter.com/nwskeywest
Area Forecast Discussion
National Weather Service Lake Charles LA
1034 PM CDT Wed Aug 28 2019
.DISCUSSION...
Grids/zones were updated earlier to account for radar
trends...most notably to increase POPs in areas where convection
was more widespread. Latest high res runs weren`t very bullish on
additional activity away from the coast overnight...but given such
moist/unstable conditions in regional 00z soundings, plus the
presence of the sfc boundary/troffing aloft, maintained slim POPs
beyond 06z.
25
&&
.PREV DISCUSSION... /issued 624 PM CDT Wed Aug 28 2019/
AVIATION...
Ongoing convection across S LA will continue over the next 2-3
hours resulting in the potential for TEMPO restrictions at
KARA/KLFT. Outflow from these storms moving east could trigger the
development of additional convection in the vicinity of KLCH
through 02Z-03Z. Convection should diminish shortly thereafter and
give way to clearing skies and light winds for the rest of the
evening.
PREV DISCUSSION... /issued 343 PM CDT Wed Aug 28 2019/
DISCUSSION...
Wx map shows diffuse cool front/trough boundary over NE TX/N LA. Radar
showing scattered thunderstorms developed over C and SC LA where
the high temperatures reached the lower to mid 90s this afternoon.
Further west across W LA and inland SE TX, thunderstorms have yet
to redevelop mainly due to this morning`s convection and outflow
boundary keeping temperatures in the mid to upper 80s. Had to load
a mixture of latest HRRR temps/dewpoints for the afternoon, as NBM
did not show this at all.
Showers and thunderstorms expected to diminish by this evening
with the loss of daytime heating. Keeping at least 20% for the
overnight hours for any development due to the proximity of the
frontal boundary. Expecting scattered late morning/afternoon
showers and thunderstorms on Thursday. The front should make some
southward progress by Thursday night into Friday-Saturday to
allow lower dewpoints and most of the precip chances to remain
over the Gulf. Should see slightly lower overnight temperatures
during this period.
By Labor Day, expected to begin seeing a return of moisture to
allow for showers and thunderstorms during the afternoon. Moisture
associated with a tropical wave over the Central Gulf will likely
return slightly higher chances of precipitation by Tuesday-
Wednesday of next week.
DML
MARINE...
Generally light and variable winds can be expected the next few
days as a weak frontal boundary settles near the coast or over
the coastal waters. Winds will trend more east to northeast and
strengthen slightly over the weekend and into early next week as
a weak trough of low pressure moves west across the Gulf.
DML
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 72 92 71 93 / 30 30 10 10
LCH 76 92 75 92 / 30 40 10 20
LFT 75 92 73 93 / 50 40 10 10
BPT 77 90 77 90 / 20 40 10 20
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...None.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service New Orleans LA
822 PM CDT Wed Aug 28 2019
.UPDATE...
Updated the grids to bring PoPS, weather and QPF in line with
current trends in the Baton Rouge to Atchafalaya Basin area. Rain
rates have been sustaining at a good clip with 3-4 inches
indicated by radar thusfar. There is a backward propagation
component to the convection northward. The HRRR wants to maintain
rainfall into SW MS for the next 2-3 hours, which may or may not
happen, but motions of any upstream developments would eventually
move into the region that is getting the bulk of the rain
currently. 24/RR
&&
.PREV DISCUSSION... /issued 408 PM CDT Wed Aug 28 2019/
SYNOPSIS...
Pressure fields and a slight lowering of dew points would indicate
frontal boundary is probably pretty close to Interstate 10 this
afternoon, with surface high pressure currently over southern
Missouri. Scattered thunderstorms have developed, mainly to the
west of a Baton Rouge to Boothville line, sinking southward a bit.
Outside of thunderstorms, temperatures have heated up into the mid
90s. A few locations such as Pascagoula and New Orleans
International did reach the Heat Advisory criteria of 108 degrees.
SHORT TERM...
Plan to allow Heat Advisory to expire at 6 pm CDT on schedule. At
this time, it does not appear that we will reach criteria tomorrow
with somewhat lower dew points expected.
Thunderstorms this evening should remain primarily south of
Interstate 10 and expect a significant diminishing trend near or
shortly after sunset. If there is any precipitation tomorrow, it
should be west of a Baton Rouge to Grand Isle line, and west of
the Atchafalaya on Friday. Moisture will start returning from the
southeast on Saturday with surface high shifting to the east
coast. Any precipitation Saturday should be east of a Biloxi to
Boothville line.
Some concern that forecast highs might be a little too cool
tomorrow if wind flow is a little more northerly than expected. In
that case, highs would warm into the mid 90s instead of lower, but
with lower dew points the next few days, heat index values will be
lower. 35
LONG TERM...
Weak tropical wave forecast to move westward across the central
Gulf of Mexico Sunday and Labor Day, with shower and thunderstorm
chances/coverage increasing Saturday night into Sunday, going
with likely PoPs for much of the area Sunday. Wave should be west
of the area by mid-day Labor Day.
Beyond Labor Day, forecast will be dependent on the eventual
track of Hurricane Dorian. Current forecast has Dorian over
central Florida Monday afternoon. There is potential for Dorian to
reach at least the eastern Gulf of Mexico early next week. For
now, haven`t made major changes beyond Monday, but forecast
confidence is rather uncertain for mid-week.
Precipitation should hold temperatures in the 80s on Sunday, with
near to slightly above normal temperatures early next week. 35
AVIATION...
An approaching cold front has produced another round of spotty
showers and storms this afternoon. At this time, better coverage
of storms will be west of I-55 but mainly along the River
Parishes and southwestward mainly affecting KHUM and KMSY. Main
threats with any one storm will be gusty downdraft winds in excess
of 25 to 35 knots, as well as periods of lower visibility within
heavier rainfall leading to temporary reductions in flight
categories. Otherwise, winds will eventually shift more from the
north through late afternoon and into the overnight hours, and
will dry out with VFR conditions expected. 18/35
MARINE...
Convection diminishes and presses south into the western portion
of the coastal waters tomorrow, then northerly winds and dry
conditions following through the rest of the week. Next focus will
be on Saturday and Sunday, as a tropical inverted trough/upper
disturbance approaches from the east. Look for increasing
shower/storm activity as well as gusty easterly winds developing.
Confidence of Small Craft criteria is low at this time, but may
likely reach exercise caution headlines. Beyond that, eventual
track of Dorian will be determining factor of forecast, with
potential for movement into at least the eastern Gulf early next
week. 35
DECISION SUPPORT...
DSS code: Blue.
River Flood Warning - Pearl River near Bogalusa.
Deployed: None.
Activation: None.
Activities: None.
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or high
visibility event; Marginal risk severe or excessive rain.
Yellow = Heightened impacts with short-fused watch, warning or
advisory issuances; radar support for slight risk severe
or excessive rain.
Orange = High Impacts; Enhanced risk severe; nearby tropical
events; HazMat or other large episodes.
Red = Full engagement for Moderate to high risk of severe and/or
excessive rainfall, or direct tropical threats; Events of
National Significance.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 71 93 68 92 / 70 10 0 10
BTR 74 93 73 93 / 80 20 0 10
ASD 73 94 70 94 / 10 10 0 10
MSY 79 93 77 92 / 40 10 0 10
GPT 74 93 71 92 / 10 0 0 10
PQL 72 94 69 94 / 0 0 0 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
725 PM EDT Wed Aug 28 2019
.SHORT TERM...(This evening through Thursday)
Issued at 322 PM EDT WED AUG 28 2019
GOES visible satellite imagery this morning shows a broad area of
clouds over the Upper Great Lakes this morning as residual scattered
showers stretch from IWD to CMX and east from P53 to ESC. Most of
these showers are remaining sub-6000 feet, as evidence from RAP
soundings and radar imagery. RAP analysis shows an early Fall 987mb
low pressure system lifting into the Hudson Bay, extending an
elongated trough across Lake Superior and the Upper Great Lakes
region. This low has kept Upper Michigan breezy through the
overnight hours and into the early afternoon today. Expect that
trend to continue right into tomorrow with a brief reprieve
overnight tonight.
For tonight, guidance is split for low temperatures with raw outputs
remaining warm, mainly into the 50s as BC models dip down into the
40s and some upper 30s away from the Great Lakes. NBM sits slightly
below the median at about the 40th percentile. Have split the
difference across Upper Michigan, given expected clearing
skies(although winds remain elevated) as the interior portions of
the UP should fall into mid 40s, with 50s expected along the Great
Lakes.
Tomorrow, another embedded shortwave is set to pass across the UP in
the afternoon. This shortwave will bring a good shot at showers and
some chances at thunderstorms from west to east. SREF plumes
continue to show near 500 J/kg across the UP from LNL to ERY. Expect
thunderstorms that do develop to remain below severe criteria, but
gusty winds will remain possible with some dry air aloft and 50
knots of bulk shear. This shortwave will move through with moderate
q-vector conv that will help support a good amount of coverage in
precipitation ahead of thunderstorm chances in the afternoon as
deeper mixing sets in. The one question will be how much moisture
return occurs after this mornings shortwave lifts north, allowing
SW flow to briefly return ahead of tomorrow`s shortwave/cold
front passage.
.LONG TERM...(Thursday night through Wednesday)
Issued at 352 PM EDT WED AUG 28 2019
Models suggest that mid/upper level troughing through the northern
Great Lakes will give way to a more zonal pattern this weekend as
the mid/upper level trough recedes to the north through Hudson Bay.
Expect temperature readings near or slightly below average for this
weekend with dry conditions under sfc high pressure. The pattern is
expected to amplify again next week as a ridge builds through the
Rockies and western Plains. As a result, a front moving through the
northern Great Lakes Mon night-Tuesday will provide the focus for
the next pcpn event.
Fri-Sun, sfc high pressure and dry air will build into the northern
Great Lakes behind Thurday`s cold front with pleasant conditions.
Expected highs in the upper 60s to around 70F with breezy conditions
on Friday will give way to light winds with lake breezes on Saturday
and Sunday with highs in the lower 70s. Lows may drop into the upper
30s to lower 40s inland with readings in the lower 50s along the
Great Lakes.
Mon-Wed, Expect rain chances to increase, especially later Monday
into Tuesday, as a frontal boundary sags into the area in response
to the amplifying pattern. Confidence in the timing and extent of
the rain is low given model differences/variability and ensemble
spread with the speed/position of the front. So, chance POPs will
continue to be utilized late Mon into Tue. Expect generally drier
conditions Wed under building sfc high pressure.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 724 PM EDT WED AUG 28 2019
Skies will clear from west to east tonight. Winds will relax a bit,
and take on a southwesterly component overnight into tomorrow ahead
of another front expected to bring showers and perhaps a few
thunderstorms. Gusty southwest winds are expected ahead of the
front, becoming west to northwesterly behind the front. Showers will
push into KIWD/KCMX by mid-morning, and then push eastward towards
KSAW in the early afternoon hours. Depending on how much instability
can build ahead of the front, could see a thunderstorms or two near
KSAW during the afternoon hours. For now have mentioned of VCTS.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 322 PM EDT WED AUG 28 2019
A few gale-force gusts will linger through this afternoon before
falling back into the mid 20 knots range. Winds will turn more SW
tonight increasing up to 30 knots at times. A cold front tomorrow
afternoon will switch winds to the NW with 20 to 25 knot gusts
persisting through Friday. After Friday, winds should remain below
20 knots through the rest of the forecast period.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Beach Hazards Statement until 9 PM EDT this evening for MIZ006.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JAW
LONG TERM...Voss
AVIATION...Ritzman
MARINE...JAW
Area Forecast Discussion
National Weather Service Phoenix AZ
430 PM MST Wed Aug 28 2019
.UPDATE...
Updated Aviation
&&
.SYNOPSIS...
Very hot temperatures are expected again today with portions of
south-central Arizona once again reaching excessive heat thresholds.
Yet another period of excessive heat is expected on Friday and
Saturday with most lower desert locations across seeing highs at or
above 110 degrees. Storm chances return to the higher terrain of
south-central Arizona again this afternoon and evening. Storm
chances may expand westward later in the holiday weekend with
isolated thunderstorms possibly even reaching southeast California.
&&
.DISCUSSION...
Latest streamline analysis indicates the center of the
mid-tropospheric anticyclone is centered just east of Yuma, which
places much of Arizona in a weak westerly flow. Across northern
Sonora, latest satellite imagery reveals a broad area of vorticity,
which is associated with cooler temperatures aloft across
southeastern Arizona. Morning CAMs indicate convection is expected
to be favored in these areas as well as along the Mogollon Rim and
higher terrain east of Phoenix late this afternoon.
Latest trends in the HRRR, local CAMs and HREF suggest a relatively
high likelihood of an outflow boundary propagating northwestward
through the Phoenix area this evening. The boundary should be
capable of producing 30 mph gusts which will likely generate at
least patchy blowing dust across Pinal and Maricopa Counties.
Official precipitation chances across the lower deserts remain on
the high end of guidance but generally less than 20 percent, mainly
owing to a pocket of warm air aloft and weak mid-level lapse rates
across central Arizona. Latest ACARS soundings indicate MLCAPE
between 500 and 1000 J/kg, along with 100-200 J/kg of CIN.
Consequently, it will generally take increasing moisture convergence
between the terrain-driven westerly flow and a strong outflow
boundary to overcome the inhibition.
Nevertheless, a few air mass thunderstorms even within the Phoenix
metro area cannot be ruled out, given the excessive heat, seasonably
high low-level dewpoints and subsequent instability. The Excessive
Heat Warning will expire this evening. With a high temperature most
likely reaching at least 110 deg in Phoenix, this will make 28 days
at or above 110 deg, moving this year into fourth place all-time.
&&
.PREVIOUS DISCUSSION...
Over the next several days, convective activity will generally fall
on the low-grade monsoon end of the spectrum. Most of the
thunderstorms that develop will focus across the high terrain east
of Phoenix or down into southeast Arizona in areas southeast of Casa
Grande. Models continue to depict occasional inverted trofs rotating
around the high, but the high itself remains rather strong each day
and centered across the central portions of the state; this tends to
shunt the disturbances/inverted trofs to the south and they track
mainly through northwest Mexico or far southern/southeast Arizona.
On Thursday, an increase in clouds/humidity from the east plus
slight weakening of the high and 850mb temps dropping to around 29C
support high temps falling below heat warning thresholds for one day.
Guidance has been very consistent lately in calling for the
excessive heat to quickly rebound Friday into Saturday. ECMPHX
ensemble guidance from the ECMWF actually calls for higher temps in
Phoenix Fri/Sat than the currently ongoing heat event. NAEFS
percentiles for 850mb temps keeps the 90+ percentile area going
across the central deserts again on Friday and Saturday, and 850mb
temps climb to near 31C by Saturday afternoon. With the high
centered to the west of Phoenix, a drier north/northeast steering
flow sets up and 500mb heights again reach or exceed 594dm. Surface
dewpoints over the lower deserts are forecast to fall in to the
upper 40s to low 50s during the afternoon hours. Everything supports
another bout of excessive heat and the Excessive Heat Warning that
was issued earlier for much of our lower deserts will continue. This
warning includes much of southwest Arizona and far southeast
California as well as south-central Arizona and the Phoenix area.
Operational as well as ensemble guidance continues to suggest that
better chances for monsoon activity will develop Sunday into the
early part of next week. The upper high finally shifts further to
the north and east and a deeper east to southeast steering flow sets
up that is able to import healthy amounts of moisture westward and
all the way into the southern California deserts. As such POPs
Sunday into Tuesday reflect conditions climbing into the moderate
grade with 10-20 percent POPs in the deserts and chance numbers over
the high terrain. One of the better chances may be Sunday afternoon
and evening as an inverted trof looks to be moving west and around
the high, increasing storm chances over the southern part of Arizona.
Of course, as clouds and humidity rise (along with potential for
actual rain and rain-cooled outflows) high temperatures will finally
drop off to near seasonal normal levels.
&&
.AVIATION...Updated at 2330 UTC.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Large forecast uncertainty into this evening is tied to maintenance
(or lack there of) of storms and outflows progressing north and west
from E/SE AZ. Moderate to high confidence exists that a better
defined boundary will progress into the Phoenix metro in the 03Z-05Z
time frame causing an abrupt wind shift some where between an
easterly and southerly direction. Lower confidence exists regarding
wind gust speeds and propagation of dust along this boundary where
lofted dust and a brief period of lower slantwise visibilities may
be the more common impact.
The lowest confidence exists with respect to the potential for TS to
be maintained or re-develop over/near terminal sites. Recent HRRR
iterations are probably most aggressive though even this output
generally only shows decaying storms. Chances of an actual TS within
a terminal footprint is probably only 10-20% at best. If storms can
form in the metro, resulting wind directions will become extremely
variable with stronger gusts potential for multiple wind shifts.
EVentually, a general easterly component should settle over
terminals beyond midnight as any activity wanes during the
overnight.
Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns through Thursday afternoon under clear
skies. Some measure of southerly winds will be maintained with
potential for some variability at KIPL through the evening/overnight.
Gusty winds at KBLH should decrease during the evening with less
gusty character Thursday afternoon.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Saturday through Wednesday:
The Monsoon High will migrate north of the area and towards the Four
Corners by early next week. This will result in an easterly flow,
which will be favorable for increasing relative humidities and at
least isolated storms each day, particularly across eastern Arizona.
Meanwhile, above normal temperatures are expected Saturday, though a
cooling trend is anticipated through the middle of next week.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST this evening for AZZ534-
537-538-540>546-548>551-553>556-559-560-562.
Excessive Heat Warning from 10 AM Friday to 8 PM MST Saturday
for AZZ530>532-534-536>538-540>546-548>551-553>556-559-560-
562.
CA...Excessive Heat Warning from 10 AM Friday to 8 PM PDT Saturday
for CAZ563-566-567-569-570.
&&
$$
DISCUSSION...Hirsch
AVIATION...MO
FIRE WEATHER...Hirsch
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
811 PM EDT Wed Aug 28 2019
.UPDATE...
Latest RAP model has broad mid level ridging across the Gulf of
Mexico. At the surface high pressure in the Gulf slips westward
as a weak inverted trough tracks from the Bahamas to across the
southern half of FL Thu...while a frontal boundary settles into
the northern part of the state. These features will shift the
onshore flow of the past couple of days to variable overnight
then northeasterly or north-northeasterly Thu. The afternoon
convection is pretty much done across the area although some will
continue overnight offshore. Have made adjustments in the near
term to better reflect the current trends and will update the
forecasts shortly. On Thu the inverted trough will bring higher
moisture to about the southern half of the state and provide the
best rain chances there.
&&
.AVIATION...
29/00Z TAFs. Limited afternoon SHRA/TSRA have just exited the
southern terminals with VFR prevailing through the period.
Although VCTS AFT 18Z-20Z could bring brief MVFR/LCL IFR. NW
winds become light/VRBL then NE AFT 15Z. However TPA/PIE/SRQ
winds back to NNW AFT 20Z.
&&
.MARINE...
Onshore winds shift tonight to northeast and east through the end
of the week. Hurricane Dorian begins to approach later in the
weekend and early next week with increasing rain chances and
winds. Please monitor the latest forecasts and information from
the National Hurricane Center.
&&
.Preliminary Point Temps/PoPs...
TPA 78 93 75 91 / 30 20 20 90
FMY 77 91 75 89 / 30 50 30 90
GIF 76 92 75 90 / 10 40 20 90
SRQ 77 92 75 91 / 30 40 20 90
BKV 75 94 73 91 / 20 20 20 80
SPG 78 92 76 91 / 40 30 20 90
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE...09/Rude
UPPER AIR...42/Norman
DECISION SUPPORT...69/Close