Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/24/18
Area Forecast Discussion
National Weather Service Cheyenne WY
545 PM MST Fri Nov 23 2018
.UPDATE...
Issued at 533 PM MST Fri Nov 23 2018
Difficult forecast to pin down for tonight as severe hazards are
expected, especially across southeast Wyoming. For the evening
update, which will be issued in the next hour, will be cancelling
the High Wind Warning a few hours early for western Carbon county
as the snow threat will take over as the main concern. Several
locations may see gusts over 50 mph, but believe this will pose
more of a risk for blowing snow/lower visibility than travel
difficulty due to winds.
For Laramie and the I-80 Summit, this is still a very tricky
forecast with relatively low confidence 6-12 hours out. For
things working against Winter Storm conditions, you have downslope
winds off the mountains and the dynamics work through relatively
quick limiting snowfall potential over the area. For things
working for it, you have strong winds which will combine with ANY
snowfall to produce blowing snow in these areas. Although the
dynamic forcing is brief (early Sat morning and again later in the
afternoon), it is strong enough to produce a period of very heavy
snow...even towards Cheyenne. With that said, feel comfortable
with a Winter Weather Advisory for Laramie based on ensembles and
the last few runs of the high res HRRR forecast reflectivity. Will
also upgrade the I-80 Summit but to a Warning mainly due to the
significant blowing snow potential with strong winds expected
through Saturday evening. Will delay this Warning for early
Saturday morning since it may take a while for the snow to
overcome the strong westerly winds.
&&
.SHORT TERM...(Tonight- Saturday Night)
Issued at 259 PM MST Fri Nov 23 2018
...High Winds & Hazardous Winter Weather Concerns Continue Through
Saturday...
Overview:
The next 24-36 hours will be extremely active across southeast Wyo
and the western Neb Panhandle. A threat for high winds is expected
to persist across a large part of the area through Saturday, but a
transition to potentially high-impact winter weather will begin to
take place overnight into early Saturday. Meteorological reasoning
behind the forecast has changed little from previous shifts, so we
will focus primarily on impacts and changes to headlines.
High Winds:
Wind gusts of 60 to 70 MPH have been common across much of the CWA
this afternoon due to an ongoing bora event. Strong gust potential
will diminish some during the evening/overnight due to the loss of
low-level mixing. However, low-level gradients will remain strong,
and a belt 50+ knot flow is expected to remain in place during the
overnight and through the day on Saturday as well. We have decided
to cancel High Wind Warnings for Converse & Niobrara counties with
wind gusts generally remaining under 45 MPH today. These areas may
see higher gusts on Saturday, but a threat for snow & blowing snow
should dominate. The remaining warnings remain largely un-touched,
except for Carbon County where near-blizzard conditions are likely
overnight. This is discussed below.
Snow & Blowing Snow in Carbon/Albany Counties:
A significant amount of uncertainty remains w/ regard to potential
snowfall amounts across Carbon and Albany counties. There has been
very little run-to-run consistency in the models, with some of the
latest guidance showing little/no snow in Laramie due to shadowing
from the Snowy Range. We have also trended lower into the Rawlins/
Elk Mountain/Arlington areas, but with winds remaining elevated it
will not take much to cause major problems. The HRRR has continued
to show decent snowfall rates overnight through Saturday, and even
a potentially significant snow squall on Saturday morning. We felt
a transition from a High Wind Warning to a Winter Storm Warning at
11 PM best serves the traveling public, as gusty winds and falling
snow will be plenty to cause near-blizzard conditions and possible
significant travel impacts even if only an inch or two falls. Will
keep the Winter Storm Watch for the Laramie Valley and I-80 Summit
due to lingering questions with the eastward extent of snow.
High Plains Snow/Blowing Snow Saturday:
We remain concerned with the potential for heavy snow banding from
east central Wyoming & into the western Nebraska Panhandle through
the morning and afternoon hours on Saturday. The models still show
a vigorous/fast-moving short wave tracking across the area w/ very
good wrap-around moisture. The primary limiting factor will be the
speed of the storm system, but with potential for wind gusts of 30
to 40 MPH the impacts could be significant. We converted the Watch
to an Advisory over Converse/Niobrara counties per coordination w/
WFOs UNR/RIW. These may be upgraded later. No changes to the Watch
for the northern Nebraska Panhandle, where we continue with a low-
confidence forecast of 3 to 6 inches of snow.
Mountain Snow:
Very heavy mountain snow will persist through early Sunday morning
with excellent orographics and dynamic support. We continue Winter
Storm Warnings with storm total accumulations of 3-4 feet expected
over the high peaks. A few SNOTELs have already received a foot or
so with the first wave. We have also added the north Laramie Range
to a Winter Storm Warning for expected snowfall in the range of 6-
12+ inches and strong winds.
.LONG TERM...(Saturday through Thursday)
Issued at 325 AM MST Fri Nov 23 2018
No major weather headlines at this stage for next week but will need
to watch the Wednesday time frame for next round of rain/snow
showers and cooling temperatures. Lower confidence exists in the far
extended pattern late next week due to model disagreement.
Deep and dry northwest flow will be ongoing Monday as a longwave
trough transits east into the Great Lakes and a shortwave H5 ridge
builds over the northern and central Rockies. This pattern will
continue into tuesday with dry and cool conditions. After the cold
weekend, temperatures will begin to slowly moderate higher into the
mid 40s by mid-week.
By Wednesday, both the ECMWF and GFS have a weak h7-H3 impulse
embedded in nearly zonal to slightly northwest flow that could aid
in enough lift for scattered mix of light rain and snow showers.
Cooling temperatures will occur late Wednesday into Thursday as
colder northwesterlies occur.
Models begin to diverge late week but generally agree that enough
shortwave ridging and subsidence should occur Thursday for dry but
cool conditions. However, by Friday and into next weekend, a more
unsettled pattern looks to take form over the central and southern
intermountain west but details remain elusive at this juncture as to
the resultant perceptible weather.
&&
.AVIATION...(For the 00Z TAFS through Saturday afternoon)
Strong winds and localized wind shear will impact aviation
operations across the region through 02Z. Westerly surface winds
will gust to around 50 kt across southeast WY, and 35 to 45 kt
across the western NE Panhandle. Winds will diminish briefly after
02z before increasing again by late Saturday morning. The next
significant impact to aviation will begin late this evening and
overnight in the form of snow and blowing snow. As of right now,
snow showers will become more numerous at KRWL and gradually spread
eastward after 03z. Believe there is a good chance for most sites to
see some snow shower activity by early Saturday morning, with the
exception of KLAR and KCYS, which may be snow shadowed for a time.
MVFR conditions will gradually lower to IFR conditions with snow,
reduced VIS, and BLSN overnight, especially at KRWL.
&&
.FIRE WEATHER...
Issued at 325 AM MST Fri Nov 23 2018
Low fire danger this period with non critical fuels. Humidity
values will drop to near critical this afternoon across the High
Plains while winds increase upwards of 25 to 35 mph. Stronger
winds will occur near Bordeaux and Arlington late this afternoon.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...High Wind Warning until 5 PM MST Saturday for WYZ104>108-115>119.
Winter Storm Watch from 11 PM MST this evening through Saturday
evening for WYZ115-116.
Winter Weather Advisory from 11 PM this evening to 11 PM MST
Saturday for WYZ104-105.
Winter Weather Advisory from 5 AM to 11 PM MST Saturday for
WYZ101-102.
Winter Storm Warning from 11 PM this evening to 11 PM MST
Saturday for WYZ103-109>111-113.
High Wind Warning until 11 PM MST this evening for WYZ109-110-
113.
Winter Storm Warning until 5 AM MST Sunday for WYZ112-114.
NE...Winter Storm Watch from 2 AM MST Saturday through late Saturday
night for NEZ002-003-095-096.
High Wind Warning until 5 PM MST Saturday for NEZ019-020-054-055.
&&
$$
UPDATE...TJT
SHORT TERM...CLH
LONG TERM...JSA
AVIATION...TJT
FIRE WEATHER...AL
Area Forecast Discussion
National Weather Service Houston/Galveston TX
950 PM CST Fri Nov 23 2018
.UPDATE...
Minor tweaks to the forecast package tonight to account for cloud
cover, temperatures, and dew points. Dry air is continuing to
filter in behind the cold front that passed through the region
earlier this afternoon. Dew points are already in the upper 40s to
lower 50s in our northern most counties from Burleson to Houston.
This has helped temperatures to cool a touch faster with 9 PM
temperatures at 50 degrees in Crockett and College Station at 55
degrees. Low temperatures tonight will dip down into the upper 40s
to 50s. GOES-16 Nighttime fog imagery shows high clouds continuing
to stream in over the region from west to east. These high clouds
will help to hinder dense fog development which can be seen over
portions of western LA and southern AR. SREF and HRRR guidance
are still indicating the potential for widespread patchy fog
across the area. Patchy fog will be possible, especially where
skies are clear during the overnight hours.
Hathaway
&&
PREV DISCUSSION... /ISSUED 342 PM CST Fri Nov 23 2018/
DISCUSSION...
Low level flow is veering to the west which is bringing some
drier air into to the region. With clearing skies and light winds
expected well into the evening, went ahead and threw in the
mention of patchy fog...although increasing cirrus could be a
limiting factor late depending on eventual coverage/thickness.
Warmer and uneventful wx is expected on Saturday ahead of the next
cold front that is still on target to push through the region on
Sunday. This front will be moisture starved so we`re not
anticipating much in the way of rainfall - especially inland.
Drier and colder airmass will build in behind the front and
persist for the first half of the work week.
Surface high pressure moves off to the east on Wed allowing for
onshore winds to resume and a gradual warming/moistening trend
going into the late week period. Re-introduced low POPs on Thurs,
but medium range solutions aren`t in the best of agreement in
regards to the timing and details of the next wx system. 47
MARINE...
A coastal low will continue to track along the Gulf Coast into the
Northern Gulf tonight. Winds veer to northwesterly tonight behind
the low as high pressure moves in and keeps winds light through
tomorrow. As the high pressure slides eastward, winds veer again to
onshore Saturday night into Sunday. A cold front will progress
offshore during the day Sunday with moderate to strong northerly
winds Sunday night through Monday. Small craft advisories will be
required with sustained winds 20-25 kts, and there is the potential
for wind gusts over 30 kts. Seas offshore increase to 7 to 9 feet.
High pressure moves in again Tuesday, allowing winds and waves to
decrease through the remainder of the week. 22
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 46 76 55 68 39 / 0 0 10 0 0
Houston (IAH) 50 75 60 73 43 / 0 0 10 10 10
Galveston (GLS) 57 70 65 74 48 / 0 0 10 10 10
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
Discussion...08
Area Forecast Discussion
National Weather Service Wilmington OH
944 PM EST Fri Nov 23 2018
.SYNOPSIS...
Low pressure traveling to Lake Superior will bring widespread
rain tonight into Saturday. Drier weather is expected Saturday
night and Sunday under high pressure. Another low is forecast to
bring showers and strong winds Sunday night and Monday.
&&
.NEAR TERM /THROUGH SATURDAY/...
Rapid onset of precipitation is expected over the ILN CWA over
the next few hours, as strengthening moisture advection at 850mb
(on the nose of a 60-70 knot LLJ) is now entering the forecast
area. Based on HRRR timing and current radar trends, 100-percent
PoPs were timed out across the CWA tonight, an increase from
previous PoP values. There have been some convective-looking
cells in central Kentucky, and even a couple lightning strikes.
A RAP analysis of MUCAPE depicts 100-200 J/kg entering the
southwestern section of the ILN CWA between now and midnight,
and soundings suggest some weak elevated instability could be
generated from a parcel starting point at around 850mb -- where
the warm and moist layer is most pronounced. So, a slight chance
of thunder has been added in for the Cincinnati area on
south/west through about 06Z.
With no let-up to the southeasterly flow overnight (and
eventually a bit of a switch to southerly flow) temperatures
will not fall too far from current values. In fact, there may be
some rises to temperatures between 06Z-12Z. Temperature grids
were adjusted for a much flatter progression through the
overnight hours.
Previous discussion >
Clouds are thickening and lowering ahead of deepening low
pressure located over the Northern Plains. As lift continues to
increase and the air column saturates, rain will develop and
overspread the area late this evening through tonight. Though
the surface low and upper trough are relatively shallow for this
time of year, rainfall will be enabled by a wide plume of deep
moisture originating from the Gulf of Mexico and Atlantic Ocean.
A potent 850 mb jet will aid in low level convergence and
moisture transport, producing a period of moderate rain. A
portion of the wind energy will make it to the surface where
gusts should top 20 knots from the south. Rainfall amounts of
over a half inch will be possible by 6 am, and temperatures
staying up in the 40s signal an all liquid event.
&&
.SHORT TERM /SATURDAY NIGHT/...
Widespread rain will be exiting east Saturday morning as the
low lifts to Canada. Precip should end Saturday afternoon as
weak high pressure works into the Tennessee Valley. Dry weather
is then expected to persist through Saturday night in a regime
of shallow moisture and negligible forcing. High temperatures in
the lower 50s will be a couple degrees above normal, while
overnight lows around 40 will be 6 to 8 degrees above normal.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Deepening low pressure and its dynamic upper level energy will
quickly approach from the southwest on Sunday. Showers will
occur as the low moves northeast to the Great Lakes through
Sunday night. WAA ahead of this system will boost highs into the
mid 50s to the lower 60s on Sunday. Lows will drop into the 30s
by Monday morning. Some lingering pcpn activity will occur on
the back side of the low into Monday morning, and with cold air
moving in behind the low, some of this could mix or change to
snow before ending. Little to no accumulation is expected. Winds
will become gusty late Sunday night into Monday. Gusty winds
will continue into Monday morning with some decrease later in
the day as the pressure gradient starts to relax. Will continue
to highlight wind gusts up to 40 mph in the HWO. Highs will warm
little from the morning lows on Monday. High pressure will
build into the region Tuesday through Thursday bringing dry but
below normal temperatures in the 30s for highs. Next weather
system may bring a chance of rain and snow Thursday night into
Friday. Highs may warm back into the lower to mid 40s by then.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
While VFR conditions are expected for the first few hours of the
TAF period, rain is on its way, and will move into the area in
the 03Z-05Z time frame. The rain will likely contain pockets of
MVFR visibilities, but the bigger issue is that ceilings will
lower through the overnight hours -- eventually to MVFR and IFR
values. In addition, there will be a period of LLWS with strong
southerly flow at 2kft off the surface.
Rain will come to an end on Saturday morning, but IFR ceilings
will continue through the day. As winds switch from the
southeast to the southwest, they may become slightly gusty,
possibly as high as 20-25 knots. A gradual improvement in
ceilings is expected during the day, with VFR conditions at
KCVG/KLUK and MVFR conditions elsewhere.
OUTLOOK...MVFR ceilings may continue into Saturday evening for
some airports. MVFR conditions and gusty winds are expected on
Sunday night into Monday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Coniglio
NEAR TERM...Coniglio/Hatzos
SHORT TERM...Coniglio
LONG TERM...Hickman
AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Indianapolis IN
1007 PM EST Fri Nov 23 2018
.UPDATE...
The NEAR TERM and AVIATION Sections has been updated below.
&&
.SYNOPSIS...
Issued at 306 PM EST Fri Nov 23 2018
A couple of upper level systems will bring rain chances to the
area tonight and again Sunday. A surface low pressure system will
bring cold air in to the area Sunday night and change
precipitation over to a mix and then snow, with light
accumulations possible along and north of I-70. Sunday night very
gusty winds will also be possible. Colder conditions will settle
in for the week, and the next chance for snow will arrive late
Thursday night into Friday.
&&
.NEAR TERM /Overnight/...
Issued at 1006 PM EST Fri Nov 23 2018
Surface analysis early this evening shows deep low pressure in
place across Minnesota with a trough of low pressure Iowa and
western Missouri and Western Arkansas. SE surface flow was in
place across Central Indiana as an initial wave of showers were
passing across the central Indiana within the SW flow aloft. More
showers were found across Illinois and Western kentucky...poised
to push northeast to Central Indiana overnight.
HRRR shows the previously mentioned rain propagating across the
forecast area through the next 4-6 hours. This seems quite
reasonable given latest radar trends. Models also support
this...showing deep saturation passing across the area near 06Z.
Thus have trended toward the 100 pops suggested by the forecast
builder. Given the lack of any cold air advection, will trend
overnight lows with a steady trend.
&&
.SHORT TERM /Saturday through Monday/...
Issued at 306 PM EST Fri Nov 23 2018
As Saturday morning begins rain should be ongoing in the northeast
counties but coming to an end elsewhere. By late morning, rain
will come to an end across the area. Clouds will be slow to clear,
and this will keep temperatures from climbing any higher than the
50s. Dry weather will continue into Sunday morning.
By Sunday afternoon though rain will again overspread the area,
this time from a surface system approaching from the plains.
Unfortunately models continue to vary in the track of this low,
and this creates issues for both timing of the system as well as
temperatures. Fortunately for central Indiana, tracks of the low
keep central Indiana in the warm sector for Sunday and until
sometime Sunday night. This should keep rain as the only precip
type into Sunday night. The timing differences in the track mean
late Sunday night is more uncertain and lower confidence, but at
this point expect to see rain change over to a mix and then
perhaps a few hours of light snow as the system pulls away. This
could produce some light accumulations along and north of I-70,
but again this is preliminary and subject to change. Precip
chances should move out Monday morning but much colder air will be
moving into place.
One aspect that seems to have increasing confidence is a windy
night Sunday night with a tightening pressure gradient across the
area as the low pressure system moves through and strengthens. The
location of highest winds in the Great Lakes/Ohio Valley is yet
to be determined, but could easily see wind gusts to 40 mph during
the overnight/early Monday morning. This will merit more
attention in upcoming issuances.
&&
.LONG TERM (Monday Night Through Friday)...
Issued at 236 PM EST Fri Nov 23 2018
Models are close enough that the model blend initialization
was accepted for most items.
Cold conditions will be the rule for much of the long term as air
arrives from Canada. Highs on Tuesday will remain in the 20s for
some areas. At the moment it appears that dry conditions will win
out in this cold pattern, but will have to watch and see if any
upper waves can squeeze out any precipitation (as the 12Z ECMWF
hints at for Wednesday).
On Thursday night and Friday, warmer air trying to return to the
area will interact with an old front to produce some precipitation.
Confidence remains low on this plays out, so left the
initialization`s chance PoPs as is.
&&
.AVIATION /Discussion for the 250300Z IND Taf Update/...
MVFR conditions are expected to deteriorate to IFR conditions
after 09Z in the wake of the approaching rain showers. Expect MVFR
conditions with the rain as it arrives as seen with the latest
radar trends. Trapped lower level moisture will lead to IFR
stratus after 09Z.
Previous Discussion Below
/Discussion for the 240000Z Tafs/...
Issued at 648 PM EST Fri Nov 23 2018
VFR Conditions are expected to deteriorate to IFR overnight.
A trough a low pressure is expected to pass across the Taf sites
over the next 12 hours. HRRR shows area of showers and MVFR
conditions are expected by 03Z-04Z across the Taf Sites. Time
heights and forecast soundings show deep saturation through the
overnight. Lingering lower level clouds and trapped moisture will
lead to some IFR conditions after through sunrise in the wake of
the departing wave.
A return to VFR is expected by Saturday afternoon as dry
air...mixing and some weak high pressure builds across the area.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...CP
NEAR TERM...Puma
SHORT TERM...CP
LONG TERM...50
AVIATION...JP
Area Forecast Discussion
National Weather Service North Platte NE
553 PM CST Fri Nov 23 2018
.SHORT TERM...(This evening through Saturday)
Issued at 301 PM CST Fri Nov 23 2018
A 700mb warm front will lift north through the Panhandle late
tonight. The model consensus suggests as a chance of light rain and
snow as the front lifts north. We should see high clouds this
evening lowering to midlevel clouds by Saturday morning. The weather
type is snow. H700mb temperatures support snow but the 800-850mb
temperatures support rain. Evaporative cooling should allow for
mostly light snow.
The temperature forecast tonight uses a blend of deterministic model
data plus bias correction for lows in the 20s. This forecast was a
few to several degrees warmer than the guidance blend and is
appropriate given the increasing cloudiness.
Frontogenesis will be operating across northern Nebraska Saturday
with an increase in convective instability across srn Nebraska
Saturday afternoon. For simplicity the forecast uses stratiform
weather types and the model consensus was the basis for rain and
snow chances. The 700mb warm front should be in SD Saturday for just
rain in Nebraska until around sunset. Snow may be underway across
Sheridan county late in the afternoon. The temperature forecast uses
the model blend plus bias correction for highs in the 40s to lower
50s.
.LONG TERM...(Saturday night through Friday)
Issued at 301 PM CST Fri Nov 23 2018
An arctic cold front slams through wrn and ncntl Nebraska Saturday
night. The model consensus, which is tight, continues to show the
storm system moving at 30 mph as it tracks from just south of the
Black Hills to near KC in 18hrs. Our snowfall is the product of
an arctic front, frontogenesis and modest negative EPV shifting
rapidly south Saturday night. The NAMnest shows a convectively
enhanced rain-snow line dropping through wrn and ncntl Nebraska
Saturday night with visibility falling to less than 1/4 mile at
times. Mb winds in the models range from 35-50kts in the models
with the RAP and HRRR the fastest. The forecast uses a guidance
blend for north winds of 25 mph gusting to 35 mph which might be
conservative given the RAP and HRRR models indicated 35 mph
sustained winds gusting to over 50 mph.
The combination of strong winds, 2 to 4 inches of snow predicted in
the new forecast, roadway icing and visibility falling to around 1/2
mile or less should produce winter weather advisory conditions at a
minimum. The winter storm watch will continue in place for this
forecast. If the NAMnest, RAP and HRRR models verify, a snow
squall warning, a winter storm warning or a blizzard warning might
be needed in a few areas for the very low visibility.
Another snow chance develops next week and snow chances are in place
Wednesday and part of Thursday. There is very little model agreement
on the timing of this system so this is a very low confidence
forecast. In fact, the forecast could be two days too fast with the
storm system moving in from the Pacific and crossing the cntl
Rockies.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 552 PM CST Fri Nov 23 2018
For KLBF...dry and cloudy conditions are expected through Saturday
afternoon. Ceilings will gradually drop to below 5000 feet by late
Saturday afternoon. Precipitation is expected to remain out of the
region until Saturday evening.
For KVTN...dry and increasing clouds are expected for the first
portion of the TAF period. Ceilings are expected to drop quicker
with cloud decks below 5000 feet by early Saturday afternoon.
Precipitation arrives by mid afternoon beginning as all rain. Rain
will slowly transition into a rain/snow mix by late afternoon.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Saturday evening through Sunday morning
for NEZ008-009-035-036-056>058.
Winter Storm Watch from Saturday evening through Sunday morning
for NEZ026>029-037-038-059-069>071.
Winter Storm Watch from Saturday afternoon through Sunday
morning for NEZ004-005-022>025-094.
&&
$$
SHORT TERM...CDC
LONG TERM...CDC
AVIATION...Kulik
Area Forecast Discussion
National Weather Service Miami FL
725 PM EST Fri Nov 23 2018
.UPDATE...
No big changes needed to be made to the previous forecast as
everything looks on track. Widely isolated showers are still
possible across far Southern/Southeastern Miami-Dade County as
indicated by HRRR and RAP13 with the higher chances over the
Atlantic waters. As stated in the previous discussion, patchy fog
is still possible across the interior and western regions of the
CWA so we will be keeping an eye on that overnight. Otherwise, a
relatively dry and quiet Friday night for South Florida.
&&
.PREV DISCUSSION... /issued 651 PM EST Fri Nov 23 2018/
AVIATION...Isold SHRA through 01Z, generally away from any TAF
sites. Generally dry overnight, with light ENE winds this eve
becoming calm/vrb overnight. Patchy fog is possible, but threat
too low to include at this time. Trend will be towards SW-W flow
by morning, picking up after 14Z to 6-8kts and 10-12kts after
16Z. A few SHRA around again in the afternoon, but
impacts/coverage expected to be too low to mention at this time.
PREV DISCUSSION... /issued 403 PM EST Fri Nov 23 2018/
DISCUSSION...
REMAINDER OF TODAY AND TONIGHT: Current 18Z WPC guidance has a
stationary frontal boundary hovering to the south of the Florida
Keys and extending on into the central Bahamas. Higher PWAT values
are centered across this frontal boundary, though lingering
moisture levels of 1.3 inches continue to persist across the
region, which was also indicated in this mornings 23/12Z sounding.
Due to inadequate instability, chance of thunderstorms have been
removed from the forecast for the remainder of today. For
tonight, predominantly easterly flow will veer towards the
southwest, decreasing the chance for rain showers throughout much
of South Florida, including the Atlantic waters (though there is
still a 15-20% chance of rain for the NE portions of the Atlantic
forecast zone). Calm southwesterly flow in combination with low-
level moisture will allow for the chance of patchy fog to develop
across the interior and western regions of the CWA. SREF is
mentioning the chance as well.
Overnight, low temps will range from around 60 degrees around Lake
Okeechobee, to mid 60s along the Gulf coast, upper 60s to low 70s
for the east coast.
SHORT TERM (This Weekend): Over the weekend, there will be
intermittent pockets of dry air and moist air advecting in across
the region, generating the chance for showers each day. Model
derived PWAT values increase to the 1.6-1.7 inch range Saturday
morning and remain rather steady throughout the end of the
weekend, allowing for the persistence of clouds as well.
Temperatures will begin to moderate into the low-mid 80s as we
move through the end of the weekend into early next week, which
are slightly above climatological norms.
LONG TERM (Monday through Thursday): Next week will get pretty
interesting weather wise, with both GFS and ECMWF honing in on
the time of FROPA. Monday looks to be fairly inactive as drier
PWATs squat across South Florida (near 1.2-1.3 inches), keeping
chance of rain very minimal. However, Tuesday into Wednesday is
the general time frame for a cold front to enter the region. As of
right now, both models are varying slightly on the arrival time
of the cold front, but both indicate passage with drier air by
late Wednesday morning to early Wednesday afternoon.
Forecasted temps look to be in the mid 70s across the east coast,
upper 60s to low 70s around Lake Okeechobee, and mid 70s across
the Gulf coast on Wednesday.
After Wednesday, models completely diverge again with ECMWF
keeping the dry and quiet weather in place across the region while
GFS brings a messy low pressure system in from the Gulf along
with its associated moisture and higher rain chances. Because of
this, the end of the long term has very low confidence. We will
see how models agree or disagree closer to next week.
MARINE...A chance of showers possible each day over the Atlantic
waters. Easterly winds around 10-12 kt will veer to the SW
overnight Friday into Saturday with occasional wind speeds up to
15 kt. A northerly swell will allow seas to increase to over 7
feet in the Atlantic with some areas reaching up to 10 feet on
Saturday. A Small Craft Advisory goes into effect this evening
through Sunday afternoon. Conditions will begin to improve late
Sunday into early next week.
BEACH FORECAST...There is a moderate risk of rip currents at the
Palm Beach County beaches. The risk of rip currents will remain
elevated along the Palm Beaches and this weekend the Miami-
Dade/Broward beaches could also see elevated rip current risk as
northerly swell works its way down the coast. Tides have been
running .5 to .7 feet above predictions recently, and this could
lead to minor coastal impacts in low-lying areas that are prone to
issues with astronomical high tides. While the current
expectation is for the impacts to remain below Coastal Flood
Statement or Advisory criteria, we will continue to monitor this.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 65 83 68 84 / 10 10 10 20
Fort Lauderdale 69 83 71 84 / 20 10 10 30
Miami 68 83 69 84 / 20 10 10 30
Naples 65 81 69 82 / 10 20 20 20
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...None.
AM...Small Craft Advisory until 1 PM EST Sunday for AMZ650-670.
GM...None.
&&
UPDATE...03/Fell
DISCUSSION...03/Fell
MARINE...03/Fell
AVIATION...88/ALM
BEACH FORECAST...03/Fell
Area Forecast Discussion
National Weather Service Marquette MI
631 PM EST Fri Nov 23 2018
.SHORT TERM...(This evening through Saturday)
Issued at 308 PM EST FRI NOV 23 2018
Water vapor imagery and RAP analysis show a mid-level ridge over the
Lower Great Lakes continuing to shift downstream in response to a
shortwave trof progressing across the Plains. At the sfc, tight pres
gradient btwn strong high pres along the Mid-Atlantic coast and low
pres trof over the Plains is resulting in gusty s winds today across
Upper MI. Under continued waa and lowering of inversion, low-level
moisture has become increasingly shallow today, and when combined
with the southerly winds, low clouds have been clearing out from w
to e, mostly quickly in areas where s winds downslope. Last of the
low clouds are now confined to a small area downwind of Lake MI
roughly btwn Escanaba-Munising on the w and Newberry on the e. Temps
have risen into the mid 30s to mid 40s.
Fcst in the short term will be driven by shortwave trof currently
over the Plains as it swings e and ne, extending from the Upper
Lakes to the Mid-Atlantic States by Sat evening. Only modest forcing
is indicated by the models, and there is little isentropic ascent
contribution for pcpn development. So, pcpn will overall be on the
light side. WBZ heights support ptype as mostly rain tonight,
especially the RAP/HRRR which have been consistently warm enough for
just rain in all the hourly runs this morning/early aftn. However,
given the isothermal look close to 0C in the low-levels, a slight
deviation cooler in the temp profile could result in snow mixing in
with the rain over the high terrain of the w. With rain, a concern
tonight will be whether the recent extended cold period and
resulting cold ground sfc leads to some icing on roadways even
though temps tonight are not expected to fall any lower than 34 or
35F over the interior w half. Based on a perusal of MI DOT road
sensor data, some sites suggest that potential. Secondary and less
traveled roads as well as sidewalks that have not been treated
recently may see some patchy icing.
Sfc trof will move across the area on Sat, but will not reach the
eastern fcst area until evening. With passage of the trof, pcpn will
diminish and/or end. Exception will be over the w where developing
upslope nw winds will aid continuation of pcpn. May become just cold
enough for a little lake enhancment as well. As colder air filters
into the area from the w on Sat, there will be a better chc of rain
to mix with or even change to snow over the interior w half. With
the aid of an upsloping nw wind, the far w, around Ironwood for
instance, may see a couple of inches of wet/slushy snow
accumulation if changeover occurs early enough in the day.
.LONG TERM...(Saturday night through Friday)
Issued at 336 PM EST FRI NOV 23 2018
At the risk of sounding like a broken record, persistent troughing
and cooler than normal conditions will be the norm through much of
the long term, with indications of a possible modest warm-up
Thursday into next weekend.
A shortwave will be exiting the area Saturday night, taking mid-
level moisture with it and leaving behind NWerly flow. Temps at 850
mb will be too warm initially to support lake effect, but with
upsloping and some remnant PVA there may be just enough lift to
squeeze out an additional 0.10" or so of QPF out of the lower levels
Saturday night over the Hurons and the spine of the Keweenaw, with
lesser amounts elsewhere across the western/northern UP. Fcast
soundings indicate cloud tops hovering at temps just warm enough to
prevent ice nucleation, so this would likely begin as mostly rain
and transition to a mix and then all snow from west to east as
temperatures rapidly cool at lower levels. This will cause any
liquid to freeze up quickly on untreated surfaces and make roadways
and sidewalks slick Sunday morning, and similar conditions will be
possible across portions of the east later in the morning as well.
Any snow accumulations would be limited to under half an inch by
Sunday morning.
As 850 mb temps cool to -10 to -12 C Sunday afternoon and winds
gradually become more Northerly from W to E by Sunday night, areas
of LES will begin to increase in coverage and intensity.
Additionally, a stronger area of low pressure that will bring some
snowfall accumulation downstate Sunday night into Monday will
augment the wind field slightly over the east, but it will likely
pass far enough to our south and east that Upper Michigan will see
little from it. The outlier GFS still wants to brush eastern Upper
Michigan with some snow early Monday and then retrograde some
remnant moisture further west on Tuesday as well, but will continue
to generally discount this solution. In all, currently expecting a
widespread 1-3" of snow by Monday evening, but some more
concentrated higher totals could not be ruled out if any convergence
zones set up.
The pattern of LES into Tuesday will be affected by how close to the
UP that low tracks. If it does follow closer to the GFS/GEM soln,
increased winds over eastern Lake Superior could enhance snowfall
totals there. A warming trend at 850 mb should begin to shut off the
LES machine later on Wednesday but additional light accumulations
will be possible until that time. At this time, Thursday looks
relatively dry with sfc temps gradually increasing back towards
seasonal norms.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 630 PM EST FRI NOV 23 2018
LLWS will come to an end at all three TAF sites this evening with
KSAW holding on the longest. The next forecast challenge is
lowering ceilings and visibilities as precipitation returns to the
Upper Peninsula ahead of the approaching shortwave. KSAW already
seeing lowering ceilings and visibilities due to upslope flow there.
Light rain will develop at all sites overnight with conditions
falling thru MVFR to IFR. LIFR conditions should develop at KSAW
late tonight, and then at KIWD Saturday morning as winds become
upslope from the west. Rain at KIWD should mix with light snow
late tonight and Saturday morning before changing over to all snow
late Saturday afternoon.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 308 PM EST FRI NOV 23 2018
Southerly winds are beginning to diminish from w to e across Lake
Superior this aftn. There still may be a few gale gusts over the
eastern part of the lake this evening. Otherwise, winds will
continue to diminish tonight, eventually falling off to under 20kt
for a time from w to e late tonight and Sat in the vcnty of cold
front that will be moving across Lake Superior. Behind the front, nw
winds will ramp up to 20-30kt from w to e late Sat aftn/night. Not
out of the question that there could be some gale gusts to 35kt Sat
night over the e half. Winds will diminish a little on Sun, but
overall, nw to n winds of 20-30kt will generally prevail Sun/Mon.
Gradual diminishing of winds should occur Tue into Wed.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...KCW
AVIATION...RJT
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Pocatello ID
229 PM MST Fri Nov 23 2018
.SHORT TERM...A communications outage earlier today limited model
updates and observations. Systems have been restored, but it will
take a couple hours yet for some spooled data to be processed.
Updates with this afternoons forecast were conservative.
Adjustments were made for representativeness.
The next round of precipitation in the storm system is approaching
from the west, rain is already being reported at Jerome and Twin
Falls. Snow levels are expected to rise late this afternoon and
evening about 400 to 800 feet across the area. Snow changing to
rain can be expected in the Eastern Magic Valley and eastward to
Pocatello this evening and northward along the Interstate 15
corridor to about Idaho Falls towards midnight. The Upper Snake
Plain may get 0.5 to 1.0 inches through Saturday afternoon. Around
5 to 8 inches more can be expected in the mountains, particularly
the Southeastern Highlands. Hazards associated with the storm
today are adequately headlined in current warning/advisory
products. A new front will cross the Snake Plain tonight, which
prompted the issuance of a wind advisory for the Lower Snake
Plain, gusts up to 45 mph are expected. Hinsberger/Survick
.LONG TERM....LONG TERM...Monday Night through Next Friday.
Due to a nationwide data/communications outage this morning that
lingered into early this afternoon, made very few changes to the
long-term portion of the forecast. We did nudge back PoPs and QPF
Mon eve with the first system as it appears most precip should hold
off until after midnight in the Central Mntns and after daybreak
elsewhere. Also trended PoPs higher by about 5-8% overnight Tues
night into Wed AM with that system based on the latest GFS/EC runs.
Much of Thurs appears to be trending a bit drier between systems,
with differences between the long-range models continuing beyond
that with attendant lower forecast confidence. Otherwise, the
previous discussion below remains valid. - KSmith/RS
The Snake Plain
while snow levels drop just after the precipitation ends.
PREVIOUS LONG-TERM DISCUSSION: Monday looks mainly dry with both the
European and GFS showing widespread precipiation arrive late Monday
night or Tuesday. European may be a tad bit faster with the onset
than the GFS, otherwise both models are pretty similar. As a whole,
it does not appear to be a heavy snow maker but much of the region
including many of the valley floors could see some light
accumulations. This system exits the region Wednesday night with
another system potentially affecting the region for Thursday and
Friday. GFS and European differ significantly with this next system.
GFS is much further north and much slower with this system than the
European. Therefore, the GFS has much more precipitation associated
with it than the European solution. Given the drastic model
discrepancy, have little to no confidence in the precipitation
chances for late next week. - Valle
&&
.AVIATION...
Our next round of precip is currently moving into western ID, and is
expected to begin impacting KSUN/KBYI by 22-23Z. Made significant
changes to the TAFs with the 18Z issuance to delay the onset and end
time of impacts with this next wave by several hours, using the high-
res HREF ensemble members and HRRR in combination with current radar
trends, which all demonstrated decent agreement. This round of
precip will drop all terminals to MVFR or IFR largely for cigs. Once
again, the greatest factor governing how low vsbys will drop will be
precip type. There is the potential for KSUN and KDIJ to drop below
airfield minimums for several hours this eve/tonight. Current TEMPO
groups at both terminals are maxed out at 4 hours...these conditions
may extend a couple hours longer. This is a difficult forecast, and
multiple TAF amendments are likely from this eve right through the
day Sat. The other story will be the winds, which will likely be
strongest from the second half of tonight into late Sat morning,
particularly at KBYI/KPIH/KIDA. - KSmith/RS
&&
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 AM MST Saturday for IDZ053-
056>059-061-065-067>070-075.
Winter Storm Warning until 6 AM MST Saturday for IDZ071>074.
Winter Storm Warning until noon MST Saturday for IDZ060-062>064-
066.
Wind Advisory from 2 AM to 9 AM MST Saturday for IDZ054.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
825 PM MST Fri Nov 23 2018
.UPDATE...
Issued at 822 PM MST Fri Nov 23 2018
NAM nest, HRRR, and RAP are all showing very strong winds over the
Southern Sangre de Cristo mountains from about 15Z Sat to about
01Z Sun. The potential for winds in excess of 75 mph looks high
enough at this time to go ahead and issue a High Wind Warning for
this area which includes forecast zones 74 and 75.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 245 PM MST Fri Nov 23 2018
...Another round of wind driven snow for the central mountains with
mainly wind elsewhere on Saturday...
Gusty winds have spread across all of southern CO as of 21z, with
gusts in the 35 to 45 mph range in and near the southeast mountains.
Gusts were in the 25 to 35 mph range for the remainder of the lower
elevations. Gusts across the higher mountains have been in the 55
to 65 mph range with Pikes Peak registering a gust to 80 mph earlier
today. Expect winds to decrease this evening, particularly over the
lower elevations with gusty winds pulling back to the higher peaks
during the evening hours. The next upper trough across the Pacific
Northwest will advance southeastward across CO on Saturday. There
were some timing differences with the NAM and GFS...with GFS quicker
with the trof passage and hence faster with the frontal passage
across the plains Saturday afternoon, while NAM has been consistently
slower by around 3 hours. This will make a difference between the
front coming through the plains during peak heating, or a little
latter which complicates the decision to go with high wind
highlights for the plains.
For sensible weather in the short term...expect wind and snow to
ramp up again across the central mountains tonight, especially after
midnight. New set of highlights are already in place and still look
on target. High res models suggest winds will stay below high wind
criteria across the mountains tonight, though higher peaks could
still gust to up to 65 to 70 mph late tonight as the upper jet from
the incoming system sags southward into the region. Best lift with
the system will come in on Saturday when the heaviest snow and
strongest winds can be expected. Snowfall totals in the 6 to 14
range can be expected across the Sawatch and Mosquito ranges with
additional light accumulations expected to continue into Saturday
evening. Of greater concern will be potential for blowing snow as
mtn top winds increase to around 60 to 70 mph as upper jet
translates in. Overall, travel is expected to be hazardous over the
mountain passes of the Sawatch and Mosquito ranges late tonight
through Saturday.
Snow will also spread into the remainder of the southern CO
mountains on Saturday, with snow spreading into the crest and
western slopes of the Sangre De Cristos and Pikes Peak and the Wets
during the afternoon. Accumulations will be much lighter, however,
with amounts generally in the 1 to 4 inch range. Higher elevations
of the La Garita Mountains could see local accumulations of up to 6
inches, but these higher amounts should be spotty in coverage.
Overall, no highlights expected for these areas as amounts look too
light.
For the eastern slopes of the southeast mountains and plains, the
main story will be the potential for strong winds. Initially, west
winds will spread down into the lower elevations of the east facing
slopes of the Sangres, Wets and Pikes Peak region during the
morning. There is some concern for potential high winds along the
eastern slopes of the Sangre De Cristo range as there will be some
reverse shear ahead of the incoming upper jet in the 12z to 18z
timeframe. However model soundings seem to lack a mountain top
inversion so a wave induced critical layer would have to develop to
help bring these winds to the surface. After 18z...wind shear
quickly progresses to forward shear as the upper jet moves in.
NamNest hints at some potential for high winds along the lee of the
southern Sangres but this model tends to run hot with wind gusts
overall. HRRR wind gusts are lower in magnitude and 12z run didn`t
show them approaching high wind criteria until the afternoon when
deep mixing helps spread some 50 to 60 mph gusts into the adjacent
lower elevations along/west of I-25. Overall, not enough confidence
to go out with a high wind watch at this point. But this will be
monitored with future model runs. Cold front will make a push
through the plains during the late afternoon and evening and think
this is when sporadic high wind gusts will be possible. However if
the later timing of the front in the NAM12 verifies, the offset from
peak heating may serve to keep wind gusts just shy of high wind
criteria (58 mph...plains). Again, will hold off on any highlights
given the low confidence. Should see falling temperatures behind the
front with snow showers developing along/behind the front across the
Palmer Divide and northern portions of the plains during the late
afternoon/early evening. -KT
.LONG TERM...(Saturday night through Friday)
Issued at 245 PM MST Fri Nov 23 2018
Windy and turning colder Sat evening as surface cold front drops
quickly south through the area. Could see some post-frontal nw
winds gust to at least 40-50 mph along and east of I-25 as surface
pressure rises quickly behind the front and strong mid-level nw
winds mix toward the surface. Will also carry a chance of snow
showers across most of the area Sat evening as upper trough swings
through, though vertical motion becomes quickly negative by
midnight as trough moves into KS and winds become nwly, so any
snow accums should be patchy and light away from the Continental
Divide, with just flurries at many locations. Breezy and cool
conditions then expected Sunday behind the departing trough, with
winds diminishing in the afternoon as surface gradient relaxes.
Max temps Sun will end up 10-20f colder than Sat across most of
the region as surface high pressure drops south through the
plains.
NW flow expected across the area Mon/Tue as upper ridge builds
through the Rockies, leading to generally dry and gradually warmer
conditions across the area. Ridge then shifts east Wed/Thu as
strong Pacific Jet pushes into the wrn U.S. with initial short
wave bringing back a chance of snow to the Continental Divide and
increasing winds to much of the area as fast wly flow moves
overhead. Still looks fairly mild both days as downslope flow and
mild Pacific air dominate. More amplified system then moves
onshore Fri and into the Central Plains over the weekend, though
usual model strength and timing issues develop, which make
confidence in details and exact location of heaviest snow still
low. Still, trend toward colder and wetter conditions looks
likely, especially over the mountains late Friday into Sat.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 245 PM MST Fri Nov 23 2018
TAF sites will remain VFR during the period with main concerns
revolving around gusty winds. West to northwest winds will continue
to gust in the 25-35 kt range for both KCOS and KPUB until 00z-01z
when winds will subside into the 10-15 kt range. However winds will
increase again on Saturday as a strong system moves across the
state. Expect southerly winds to shift from the west at all three
terminals with gusts to around 40 kts by mid afternoon. A cold
front will drop southward through KCOS and KPUB by 00z bringing a
sharp wind shift from the north and the potential for wind gusts to
around 45 kts through early evening. Some brief VFR cigs will be
possible with -SHSN at KCOS during the early evening...though these
showers will be brief with little to no accumulation expected. There
could also be some LLWS to the west of KCOS and KPUB late tonight
through early Friday but this appears to stay well west of the
terminal.
KALS will see lighter winds tonight...but should see gusts to 35 kts
from the west to northwest late Saturday afternoon and evening.
Brief VFR cigs will be possible Saturday evening with localized
-SHSN. Little to no accumulation is expected. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 5 AM MST Sunday for COZ059-061.
Winter Storm Warning until 5 AM MST Sunday for COZ058-060.
High Wind Warning from 8 AM to 6 PM MST Saturday for COZ074-075.
&&
$$
UPDATE...28
SHORT TERM...KT
LONG TERM...PETERSEN
AVIATION...KT
Area Forecast Discussion
National Weather Service Shreveport LA
921 PM CST Fri Nov 23 2018
.UPDATE...
Drier air that was supposed to be moving into our region from the
west has put on the breaks this evening and given the late nature
of the clearing earlier today combined with a wet ground and light
winds, fog has developed across portions of the region this
evening. The cloud cover did not completely clear our eastern
zones earlier and in fact, has tried to redevelop or expand its
way back to the west over the last 3 hours or so. Have adjusted
areas of fog vs patchy fog wording in the grids but at this time,
the dense nature of the fog is very patchy and as a result, will
not issue a Dense Fog Advisory at this time. Also made some
adjustments to hourly temperatures and dewpoints as well as sky
grids but feel like overnight min temps are in the ballpark so no
changes are necessary.
Update out shortly...13.
&&
.PREV DISCUSSION... /issued 513 PM CST Fri Nov 23 2018/
AVIATION...
IR Imagery early this evening showing improving conditions with
showers quickly exiting our region to the east. Remaining cloud
cover is across our eastern airspace across N LA and S AR with IFR
ceilings noted over or in the vicinity of the ELD/MLU terminals as
of 23z. Winds have diminished quickly during the last hour and
with a surface trough noted just north and west of our airspace or
across Eastern Oklahoma into North Central Texas attm. This
boundary will continue to move into the region from the northwest
overnight but am getting concerned with fog potential ahead of
this boundary as NAM MOS and latest HRRR output showing the
potential for Dense Fog across at least the ELD/MLU and LFK
terminals. Thus have added this mention during the overnight hours
and we will have to wait and see if the drier air winds out in
time further west, encompassing the TXK/SHV terminals. Feel safe
that if the TYR/GGG terminals see any fog it would be brief and of
the patchy nature closer to sunrise but we will continue to
monitor the fog potential through the night.
Any fog concerns Sat morning should lift and or scatter out by 16z
or so with light south winds returning along with VFR conditions.
13
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 45 69 54 66 / 0 0 0 10
MLU 48 68 53 69 / 0 0 0 20
DEQ 42 67 48 59 / 0 0 0 10
TXK 43 67 50 62 / 0 0 0 10
ELD 45 67 51 65 / 0 0 0 10
TYR 43 72 53 63 / 0 0 0 10
GGG 45 71 54 64 / 0 0 0 10
LFK 48 73 56 69 / 0 0 0 10
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
13/13
Area Forecast Discussion
National Weather Service Tallahassee FL
748 PM EST Fri Nov 23 2018
.UPDATE...
Still expect areas of rain to develop later tonight across mainly
the western and southern portions of the forecast area. Areas of
fog also remain possible. The main change was to add an isolated
thunderstorm mention to portions of the Florida panhandle and
southeast Alabama. The 23z RAP forecast soundings show elevated
instability reaching as far north as the Dothan area towards
sunrise. MUCAPE values for a parcel based around 800 mb are in the
700-800 j/kg range on the RAP according to BUFKIT forecast
soundings, which could support a few rumbles of thunder. However,
the airmass in the low levels looks rather stable with dewpoints
below 60, so no severe weather is expected. Farther south, the RAP
does move some higher surface dewpoints inland across the Florida
panhandle late tonight, but the 18z NAM and GFS are less
aggressive. Looking offshore south of Mobile, most dewpoints are
in the lower 60s, so the RAP idea of mid 60s dewpoints moving
onshore late tonight seems overdone.
&&
.PREV DISCUSSION [653 PM EST]...
.NEAR TERM [Through Tonight]...
Shortwave energy moving through the Tennessee Valley will induce
weak low pressure along a developing frontal boundary southwest of
the area over the Gulf of Mexico. A wedge of drier air is
expected across southwest GA, with deeper moisture elsewhere.
Isentropic ascent will increase across much of the area,
especially the far Western Panhandle and Southeast Alabama, as
well as the Southwest Big Bend. These locations could have some
brief heavier downpours, with localized rainfall amounts up to one
inch. Any thunder should remain well south in the Gulf.
Elsewhere, rain showers, with the exception of southwest GA, where
it may remain relatively dry. This area southward into the FL
Panhandle in the vicinity of the I-10 corridor is where fog
potential will be greater tonight, given the moist low-level air
mass and drier mid-level air aloft, and dense fog is also
possible. Low temperatures will be above average in the low to mid
50s.
.SHORT TERM [Saturday Through Monday]...
Low pressure will move eastward along a frontal boundary south of
the area on Saturday and gradually weaken. Precipitation coverage in
the form of rain showers will decrease throughout the day given a
top down drying of the column and increasing subsidence as mid and
upper level support moves well northeast of the area. Therefore, the
highest chances for precipitation will be during the early morning.
Any fog that develops overnight may linger into the late morning,
especially from Southwest GA southward into the FL Panhandle in the
vicinity of the I-10 corridor. Despite the drier air advecting in
aloft, model soundings indicate a saturated layer below a
persistent low-level inversion. This translates into considerable
cloudiness through at least the early afternoon, when the
inversion begins to weaken, and cloud cover decreases. High
temperatures on Saturday will be near normal, ranging from the
mid-60s to mid-70s.
With substantial low-level moisture remaining in place on Saturday
Night, some clearing, and light winds, expect another round of fog
which could potentially be more widespread and dense compared to
tonight. Low temperatures again in the low to middle 50s.
On Sunday, any fog should dissipate in the morning, with increasing
cloudiness mainly north of I-10 as a cold front approaches the area.
Cannot rule out a shower mainly over Southeast Alabama and the
Western FL Panhandle late in the day, otherwise dry. Highs above
average in the 70s.
A cold frontal passage will occur Sunday Night into Monday. The more
favorable jet dynamics and lift will remain northwest of the region,
so precipitation in the form of rain showers should be tied more
directly with the passage of the front. The SPC Day 3 Outlook ending
Monday Morning indicates general thunderstorms in the Western FL
Panhandle. While the wind field is rather robust, instability is
both weak and elevated, with considerable Convective Inhibition
(CIN). If some instability can work onshore closer to the coast
where low-level lapse rates are steeper, which is more favored as
the day goes on, although highly dependent on the timing of the
front, then a strong thunderstorm cannot be ruled out. But overall,
the severe weather threat is low at this time.
Otherwise, modest cold air advection in the wake of the front should
maintain considerable cloudiness across the region, despite a drying
trend. Lows above average in the mid-50s to mid-60s and highs below
average in the 60s.
.LONG TERM [Monday Night Through Friday]...
In the wake of the cold frontal passage, high pressure will build
into the region on Tuesday and settle over the area on Wednesday.
This gives the opportunity for frost Monday Night and especially
Tuesday Night. A more unsettled pattern develops Thursday into
Friday with low pressure developing in the Gulf Of Mexico, and
that presents the next chance of precip during this time frame.
Temperatures through the period will average below normal, with
highs in the upper 50s on Tuesday, moderating into the low to
mid-60s by Thursday.
.AVIATION...
[Through 00Z Sunday]
Degraded flt conds expected to persist into Saturday. Currently,
high IFR to MVFR conds at all TAF sites. Cigs will lower to
LIFR/IFR by late evening. Vsbys will also be reduced in BR or FG
and some light SHRA in the overnight timeframe. Gradual
improvement expected beginning late morning Saturday as drier air
filters in on nwesterly winds. A return to VFR is possible towards
the tail end of the TAF period, especially DHN/ECP where drier air
reaches earlier than the other sites.
.MARINE...
Southeasterly flow around 10 knots or less becoming southwesterly
Sunday Afternoon ahead of a cold front. The cold front will move
through the waters Sunday Night into Monday with winds increasing
out of the northwest to around 20 knots into early Monday Night.
A Small Craft Advisory may be needed during this time frame. Seas
increase accordingly into the 4 to 6 foot range. A return to more
tranquil boating conditions is expected on Tuesday and Wednesday.
.FIRE WEATHER...
Wetting rains are possible tonight into Saturday night and once
again to start the next work week. No hazardous fire weather
conditions are expected the next few days.
.HYDROLOGY...
There will be two opportunities for light precipitation through
early next week: the first with low pressure passing south of
the area tonight and early Saturday and the second with a cold
frontal passage Sunday Night into Monday. While isolated rain-
fall amounts up to one inch are possible across the far Western
Panhandle and Southeast Alabama, as well as the Southwest Big
Bend, most locations will receive up to around 0.5 inches of
rain. Another low pressure moving through the Gulf presents
the next opportunity for precip Thursday into Friday. At this
time, rainfall amounts across the aforementioned areas may
reach 1 to 1.5 inches through Friday, with generally less than
one inch elsewhere. While some rivers remain at action level,
additional flooding is not expected at this time, given the
limited amount of precipitation forecast.
.SPOTTER INFORMATION STATEMENT...
Spotter activation is not requested. However, spotters are always
encouraged to safely report significant weather conditions when they
occur by calling the office or tweeting us @NWSTallahassee.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 55 74 54 75 59 / 50 30 10 20 50
Panama City 58 74 58 74 57 / 60 40 10 20 60
Dothan 51 69 51 72 51 / 50 40 10 10 50
Albany 52 70 50 73 56 / 40 30 10 10 50
Valdosta 55 73 54 75 60 / 40 20 20 10 40
Cross City 59 75 58 76 64 / 40 30 20 20 40
Apalachicola 59 73 59 73 61 / 60 40 10 20 60
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
UPDATE...DVD
NEAR TERM...LF
SHORT TERM...LF
LONG TERM...LF
AVIATION...Scholl
MARINE...LF
FIRE WEATHER...Scholl
HYDROLOGY...LF