Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/13/19
Area Forecast Discussion
National Weather Service Bismarck ND
909 PM CDT Fri Apr 12 2019
.UPDATE...
Issued at 909 PM CDT Fri Apr 12 2019
Latest local/regional radar shows the back edge of higher
reflectivities supporting scattered snow showers extends from
Carrington to Jamestown, and snaking back into Linton. This is on
track to weaken and exit the southern James River Valley between
10PM and 11PM CDT. Surface high pressure in southeast Saskatchewan
will slowly shift into western South Dakota by 12z Saturday.
Clouds will gradually decrease from west to east overnight. Minor
adjustments to PoPs and sky cover overnight based on the above
discussion.
UPDATE Issued at 552 PM CDT Fri Apr 12 2019
Upper low now in eastern Minnesota continues to rotate clouds and
scattered snow showers into central ND. Radar reflectivities
continue to show a weakening trend with a north to south movement,
and PoP trends from previous forecast looks good. Expect the
majority of the snow showers over the James River Valley, and less
farther west this evening. Still quite a bit of strato-cumulus
clouds across western ND, with overcast conditions for most of
central ND. Following the HRRR 925mb Relative Humidity fields
overnight, expect a gradual clearing west into central, with the
southern James River Valley holding onto the clouds until 10-12z
Saturday. Per RAP BUFKIT soundings at Jamestown, Ashley and
Oakes, prospects of fog where we had heavy snowfall looks low at
this point, given the the persistent clouds through most of the
night and high enough winds/turbulence within the lower boundary
layer to inhibit the threat for fog.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 322 PM CDT Fri Apr 12 2019
Water vapor analysis places the closed low centered over
Minnesota with western and central North Dakota under a region of
increasing upper level confluence. Scattered snow and rain showers
wrap around the back side of the associated surface low this
afternoon before tapering off from west to east through the
evening as a surface high builds from the west. Clearing skies
tonight with diminishing winds will drop low temperatures into the
low 20s with upper teens possible in some areas. The challenge
tonight with lows will be how quickly cloud cover can vacate. If
skies clear over areas with fresh snow, temperatures may need to
be lowered. While there is an outside chance of fog with the fresh
snowpack, the placement of the surface high axis to the west of
the snowpack tonight doesn`t give enough confidence to include
mention in the forecast.
For Saturday, a weak mid-level ridge builds over the state with a
surface high centered over central South Dakota. With clear skies
high temperatures reach the mid 50s in the west and 40s in the
south- central.
.LONG TERM...(Saturday night through Friday)
Issued at 322 PM CDT Fri Apr 12 2019
Temperatures will warm to near average for next week as zonal flow
begins to dominate, with some chances for mixed precipitation
throughout the extended forecast.
First chance of precip is Sunday night into Monday morning with a
weak warm front dragging south of a clipper. The main issue is
going to be what kind of mixed precip, with daytime highs in the
40s and 50s and Sunday night`s low right around freezing. Both the
12Z GFS and ECMWF have very light QPF, along with just a chance of PoPs
in the grids overall. Therefore, whatever p-type we end up
getting, likely won`t be too much of it.
Very slight cooldown after the first system before a potentially more
significant storm for the Central Plains midweek, with again some
possible p-type issues. GFS has the system faster and weaker than
ECMWF, resulting in a more spread out precipitation field north
of the low, whereas ECMWF has precip ending close to the ND/SD
border, leaving us out completely. There`s a wide spread in QPF
possibilities from the 0Z GEFS plumes so still plenty of
uncertainty this far out.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 552 PM CDT Fri Apr 12 2019
KJMS will continue to experience mvfr cigs and periods of mvfr
visibilities in -shsn until 05z Saturday, then gradually returning
to vfr by 10z. Elsewhere, low vfr cigs at the remaining terminals
to start the 00z taf cycle will undergo a gradual clearing sky
overnight into most of Saturday.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KS
SHORT TERM...AE
LONG TERM...MJ
AVIATION...KS
Area Forecast Discussion
National Weather Service Denver/Boulder CO
852 PM MDT Fri Apr 12 2019
.UPDATE...
Issued at 852 PM MDT Fri Apr 12 2019
This afternoon and evening`s convection was not as strong as many
models had been predicting. Current radar and GOES-16 imagery
snowing convective snow showers (even some rain) continuing to
move across the area with minimal impacts so far. The current
batch of showers is being forced by an approaching trough axis and
a strong pool of cold air aloft. Upslope enhancement is not
expected to be much of a factor tonight for any particular
location across the foothills and Palmer Divide, thus it`s
difficult to pin down any favored area for better snow chances.
The 00Z KDNR sounding showed very steep lapse rates all the way to
the tropopause and it is -26degC at 500 mb. Suffice to say
convective snow showers with the trough axis still back over
central/eastern Utah will be possible across a good part of our
area until about 5 AM or so. Coverage at this point still appears
spotty but around a half inch could fall with any shower/batch of
showers right overhead. We think at most 1-2 inches in a few
spots are possible through sunrise. Temperatures for the next
several hours are still warm enough to result in wet pavements, so
accumulation should be restricted to the grass until after
midnight. Any snow that falls after midnight could result in slick
spots on roads, especially for bridges and overpasses given air
and road temps gradually falling below freezing after midnight.
The forecast overnight is mostly on track. We reduced snow
amounts through midnight given what we`ve already seen vs. what
the high res models tried to generate, and adjusted PoPs to
reflect where the HRRR is trending the convective snow showers
after 10 PM or so.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 346 PM MDT Fri Apr 12 2019
An upper trough axis stretching along western Colorado state line
down onto old Mexico will slowly move east overnight where it will
become a cutoff low near southeastern NM and western TX by
Saturday morning. Instability in the airmass over Colorado is
allowing scattered snow showers to spread across the mountains and
urban corridor. Upward QG lift will be increasing this evening as
moisture streams up from southern Colorado, while northeasterly
winds from a surface high pressure over the northeastern plains should
focus shower activity over the higher terrain along and south of
I-70 and east over the Palmer Divide. Seems as the hourly high res
models keep pushing the brunt of the showers a little later each
run. So this may be closer to the later evening, rather than
affecting the evening commute. As the night progresses, these
showers will move east and north over the front range urban
corridor and adjacent plains. 700 mb flow will be southerly, so
should start to downslope and dry out further north from the
Palmer Divide and into the metro area. 2 to 3 inches are expected
over the Palmer Ridge while less than an inch is expected north.
The mountains will likely see 1 to 3 inches, except 3 to 6 inches
south of I70 and into the southern foothills.
Quite a bit of model discrepancy of chances for precipitation
past midnight out on the eastern plains. GFS is the heaviest and
furthest north and east with snow continuing, so would like to
consider it the outlier and not nudge the forecast toward it.
However the 18z NAM came in following its solution, have stretched
some of the PoP and QPF north into the eastern Colorado counties.
The trough axis will pass overhead Saturday, though QG lift will
be decreasing. Some showers still expected, still favoring the
higher terrain, with a slight chance of thunder being heard late
afternoon over the mountains and urban corridor. Only small pea
size hail would be expected however. Temperatures will be similar
to slightly warmer tomorrow.
.LONG TERM...(Saturday night through Friday)
Issued at 346 PM MDT Fri Apr 12 2019
Northwesterly flow aloft is expected over the CWA on Saturday
night. Flat upper ridging is in place Sunday into Monday.
Southwesterly flow aloft is progged the rest of Monday and Monday
night. The QG Omega fields have downward vertical velocity for the
CWA Saturday night through Sunday evening. Benign energy is place
Sunday overnight through Monday evening, with upward upward
motion to move Monday overnight. The boundary layer winds will
follow normal drainage patterns during the nights, with the weak
downsloping flow to dominate both Sunday and Monday. For moisture,
there is some lingering around early Saturday evening, then the
moisture is pretty sparse in most areas. There will be some
moisture in the high mountains Sunday into Monday. There might be
a tad of upper level cloudiness in some areas Sunday through
Monday night. There is practically no CAPE progged over the CWA
Saturday night through Monday night. There are tiny amounts over
measurable precipitation on the QPF fields Saturday evening,
Sunday afternoon & night, and late day Monday. It is indicated
over the far northwestern corner of the CWA those periods. For
pops will go with "chances" over the high mountains, especially
zone 31 mainly during the late day/evening periods. For
temperatures, Sunday`s highs are 5-12 C warmer than Saturday`s
highs. Monday`s highs are 3-4 C warmer than Sunday`s. For the
later days, Tuesday through Friday, there will be southwesterly
flow aloft on Tuesday, with an upper trough to moves over the CWA
Tuesday night into Wednesday morning. Northwesterly flow aloft is
then in place the rest of the week. There will be decent moisture
around Tuesday afternoon through Wednesday night. Moisture will
linger, especially in the mountains into Friday morning. There is
measurable precipitation noted from Tuesday afternoon through
Wednesday evening. There is some to continue, mainly in the
mountains, into Friday morning. Tuesday is still above normal for
temperatures, then they cool off the rest of the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 852 PM MDT Fri Apr 12 2019
Challenging meteorological forecast for the TAF sites tonight and
Saturday but overall the impacts are expected to be fairly well
handled despite the uncertainty in wind/snow/rain/CIG. First,
convective snow showers continue to be possible at all three
terminals tonight. Runway temperatures continue to be warm this
evening so do not expect any accumulation on runways through about
midnight. After midnight, snow accumulation on the runways will
be possible as temperatures drop. Current thinking would be up to
a half inch accumulation through 3 AM or so. Can`t rule out an
inch of snow if more than one shower moves over an airfield. By 3
or 4 AM the threat of accumulating snow should be over. Winds
will remain 10 kts or less, generally out of the east or east-
southeast. CIGs and VIS have been hard to pin down with these
showers, but generally we believe MVFR will prevail, even in the
snow showers. There is an isolated chance of brief IFR conditions
if any showers are heavier than expected. Saturday morning after
sunrise conditions should be MVFR and dry, and improve to VFR by
midday. Winds should shift to north around midday and then another
round of convective showers after 2 PM are possible at all three
terminals. At this point, it looks like precipitation will fall as
rain and MVFR conditions expected during any precipitation.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Schlatter
SHORT TERM...Kriederman
LONG TERM...RJK
AVIATION...Schlatter
Area Forecast Discussion
National Weather Service Caribou ME
926 PM EDT Fri Apr 12 2019
.SYNOPSIS...
An occluded front will cross the area with showers tonight. Low
pressure lifting up to our west will track into Canada late
tonight into Saturday. High pressure will build over the area
Sunday. Low pressure will approach from the southwest on Monday.
&&
.NEAR TERM /THROUGH SATURDAY/...
Update...
Latest radar reflectivity imagery shows a broken line of showers
stretching from the St. Lawrence seaway southwest into New
Hampshire. Have lowered pops early this evening, as showers have
been slower to push into the forecast area than previously
forecast. Latest HRRR still indicating showers will move into
most of the area after midnight, or shortly thereafter. Thus,
will hold onto categorical pops after midnight. We did lower six
hourly QPF amounts in to 00z to 06z time frame, with the slower
onset of showers into the forecast area. Adjusted current
temps/ dew points based on latest observations, but no changes
to previously forecasted overnight lows.
previous discussion
Low pressure lifting up to our west will pull an occluded front
across the area tonight bringing clouds, a mild breeze and some
showers. Around a quarter inch of rain is expected overnight
with most of the rain falling from mid evening until around
dawn. The front will continue east on Saturday with mild air
remaining in place and a corridor of drier air aloft moving
over. This will bring a breezy and warm day Saturday with many
areas reaching 60 during the afternoon under a partly to mostly
sunny sky. Temperatures will be cooler along the coast.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
For Saturday night, a cold front will exit the area in the
evening and stall in the Gulf of Maine. There will be cold air
advection after the warmest day of the year to date. H925
temperatures will fall about 12C from Saturday afternoon into
early Sunday morning, but the boundary layer will be slow to
cool with steady winds through the night and temperatures will
stay above freezing except in the Saint John Valley and Allagash
regions where temperatures may touch 32F. Temperatures will
warm up quickly Sunday morning back into the mid to upper 40s
north and low to mid 50s towards Bangor and the coast. The coast
will benefit from the offshore winds. There will probably be
some cumulus field in the morning for northern zones. However,
high clouds will increase for the entire area in the afternoon
as a warm front lifts northward ahead of a low pressure system
in the Ohio River Valley. The clouds continue to thicken Sunday
night with precipitation breaking out. The antecedent air mass
is not cold. The only hope for anything but rain will be sleet
in northern Aroostook due to wet bulbing as the air mass will be
quite dry initially. Warm air above H850 will arrive quickly
and prevent anything more than a brief period of snow at precip
onset in the Saint John Valley. The sleet could last through a
good part of the morning for northern Aroostook. It will remain
chilly for the entire area on Monday under the steepening
frontal inversion and have lowered highs for Monday...especially
in the north...which will stay north of the warm front with a
cool east surface flow. Tried to factor out MOS and BC guidance
in favor of raw model temps. In general, the latest guidance
does continues to take the surface low further west...which
leads to warmer temps aloft. H925 temps will increase towards
15C along the coast by Monday afternoon. This thermal
ridge...and cooling aloft ahead of an approaching upper
trough...could serve as a base for elevated convection Monday
afternoon in southern zones. The surface low will try to re-
develop near the coast Monday afternoon...adding to the
potential for convection. Overall, the low pressure system will
generate about an inch of precipitation for most of the area.
In terms of hydro concerns, the response from the weekend warmth
and snowmelt...and then rainfall, could result in ice movement
and subsequent jamming for Aroostook County rivers such as the
Aroostook and Saint John by Monday. Further south, there`s less
ice remaining and just a few potential trouble spots in terms of
jamming. The worry by Monday night into Wednesday will be river
levels rising into minor...or potentially moderate...flood
levels for the rivers in the southern half of the area to
include Penobscot and Piscataquis basins. Our combined T/Td
thawing degree hour forecast is the highest since last April`s
flooding events. Anyone with interests and/or property along the
rivers in the forecast area should pay particularly close
attention to developments early next week.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
Colder air returns Monday night to slow melting, but
temperatures will remain mostly above freezing. P-type will
gradually shift to snow in the north, but not convinced amounts
will be as robust as the current operational GFS. Winds will be
robust on Wednesday with gusts over 30 mph likely as Monday`s
low moves into the Canadian Maritimes. Cold air advection and
clouds will limit Tuesday`s highs to readings not too far above
the morning lows. High pressure builds Tuesday night into
Wednesday. Highs return to the 40s to near 50F for Wednesday,
but subfreezing temps will slow melting Tuesday and Wednesday
nights. A warm front will lift northward across the region on
Thursday and introduce warm and humid maritime air for Thursday
night into Friday night. Heavier rainfall is possible Friday
night as a deep meridional trough over the eastern US pulls
moisture from the Gulf of Mexico northward towards Maine. The
combination of temperatures, dew points and rainfall will renew
hydro concerns Friday into Saturday. Will have to hope that the
front remains progressive and does not stall over the area
Friday night into Saturday.
&&
.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
NEAR TERM: Conditions will lower to MVFR then IFR tonight in
lowering clouds and showers. IFR conditions early Saturday
morning should then improve to MVFR by mid morning then VFR by
midday as drier air moves in.
SHORT TERM: Expect predominately VFR conditions Saturday night
into Sunday evening. Conditions will deteriorate to IFR cigs and
tempo IFR vis in rain/snow and sleet early Monday morning. Snow
and sleet exit the forecast by Monday afternoon, but IFR cigs
and rain remains. Embedded thunderstorms towards BGR and BHB are
within the realm of possibilities Monday afternoon. Conditions
improve to VFR for Tuesday into Wednesday with the exception of
MVFR cigs tempo IFR snowshowers north of HUL and GNR on Tuesday.
&&
.MARINE...
NEAR TERM: A SCA will be up from late this evening through
Saturday for southwesterly winds increasing to 25 kt. Some
patchy fog is possible over the waters late tonight into early
Saturday morning.
SHORT TERM: SCA conditions are possible Monday into Tuesday on
the waters. Fog may accompany the winds later Monday, but lift
Monday night.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory until 8 PM EDT Saturday for ANZ050>052.
&&
$$
Near Term...Bloomer/Duda
Short Term...MCW
Long Term...MCW
Aviation...Bloomer/Duda/MCW
Marine...Bloomer/Duda/MCW
Area Forecast Discussion
National Weather Service Hastings NE
652 PM CDT Fri Apr 12 2019
.SHORT TERM...(This evening through Saturday)
Issued at 326 PM CDT Fri Apr 12 2019
Aloft: A longwave trof extended from MT-AZ with ridges along the
E and W coasts...per RAP dynamic tropopause analyses and aircraft
obs. The low that affected the rgn Thu was lifting out of the mean
trof to LkSup. A shrtwv trof was at its base just S of AZ/NM.
Cyclonic WNW flow over NEB/KS back to SW and become anticyclonic
tonight into tomorrow...as the LkSup low heads into Canada and the
shrtwv trof moves out of MX into TX and strengthens. Meanwhile...
the Wrn longwave trof will move E to the High Plns by 00Z/Sun.
Surface: The influence of the cyclonic flow lingering over the
rgn was dcrsg with a strip of wk high pres building in.
Anticyclogenesis will occur over NEB tonight...with the high
strengthening overhead. This high will drift N into SD tomorrow as
strong low pres moves acrs TX.
Rest of this afternoon: Chilly with NW winds gusting 30-40 mph
pushing WCI`s into the upr 20s at times.
Plenty of stratocu in the linger cold air...espcly N of Hwy 6.
Cld depths will be aprchg their peak and some of the most robust
stratocu could produce some sprinkles/ flurries.
Diurnal clds will rapidly dissipate in the 1-2 hrs prior to
sunset.
Tonight: Winds will drop off early. Mstly clr to start...but
probably turning p/cldy S of Hwy 6 as mdl X-sections show some
potential for mid-lvl clds. They`ve been on satellite all day
over Wrn KS/Ern CO.
Cold with lows in the 20s.
Sat: Becoming mstly cldy as a large shield of cirrostratus moves
into the area from the TX system. Warmer than today but still 10F
cooler than normal.
.LONG TERM...(Saturday night through Friday)
Issued at 326 PM CDT Fri Apr 12 2019
Aloft: The flow will temporarily deamplify. A low-amplitude
shrtwv rdg will move thru Sun with zonal flow Mon. A strong shrtwv
trof will move onshore in the W Mon night. The flow will amplify
as it moves inland and digs...with winds backing to SW here on the
Cntrl Plns. This trof will move thru Wed. Mdls are fcstg lee
cyclogenesis. The 500 mb low is fcst SW-NE acrs KS. Highly-
amplified NNW flow will linger into Thu-Fri.
Surface: High pres will drift E of the rgn Sun while low pres
forms over AB with a cool front advancing thru the Wrn USA.
Downslope warming will induce warm frontogenesis from ND-TX. This
warm front will lift acrs the CWA Mon while the wk cool front
advances into Nrn Plns. The cool front will move thru Mon night
and become stationary acrs KS Tue...anchored by a new lee low fcst
to form over CO. This low is fcst to eject acrs KS/NEB Tue night
into Wed...but there is considerable spread among the last 2 runs
of global mdls on location /timing. This has important
implications for how far the warm sector lifts N...instability/svr
wx...and dare I say snow potential Wed night. See below. The rgn
will be in the cold sector Thu as low pres departs to the NE. High
pres should build in Fri.
Temps: Inching back close to normal Sun...but trimmed temps NW
1/3 for remaining snow cover. Warmer than normal Mon-Tue by about
10F. Wed very uncertain. It could be incredibly cool (highs in the
40s) if the warm front and low remain S of the CWA...or some 70s
could occur over the SE 1/2. Thu-Fri cooler than normal.
Precip: There could be some sprinkles along and N of I-80 Sun
night. Probs are not high enough to include in the fcst...but we
may need to add them when this period gets into the short-term.
Some more sprinkles could also occur N of I-80 Mon night as well.
Then we await the system for Tue night-Wed night. The lack of
consensus on the storm track precludes providing any details. We
will be watching potential for svr tstms ahead of the system and
possibly some wraparound snow as temps cool Wed night. There will
be potential for high winds as well.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday)
Issued at 625 PM CDT Fri Apr 12 2019
VFR conditions are expected to continue throughout the TAF valid
period. The wind will die down this evening and could become light
and variable at times Saturday morning before eventually becoming
northerly by late morning.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Kelley
LONG TERM...Kelley
AVIATION...Wesely
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1040 PM EDT Fri Apr 12 2019
.SYNOPSIS...
A weak cold front will stall across the region through Saturday
maintaining a chance of showers and storms. A stronger system will
bring more widespread storms to the area on Sunday and Sunday night,
with severe weather possible. The weather will improve significantly
through mid-week next week, with the next system expected Thursday
through Friday.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 1030 PM...As the HRRR has been advertising, convection
continues to struggle to redevelop across the CWA this evening. PoPs
were tweaked to reflect the trends. Still expect some uptick in
showers late tonight. Temps are on track, mainly in the 60s to lower
70s and falling slowly.
Later tonight, a cold front will sag SE into the area, stalling
roughly along the I-40 corridor by daybreak Saturday. A light S/SWLY
in the low-levels will likely trigger some showers late tonight thru
Saturday morning, as isent lift increases on the south side of the
stalled frontal zone. PoPs ramp up to the chc range for most of the
area. Thunder chances look low overnight. Unless training of showers
develops, the hydro risk still appears fairly low. Low temps will be
above normal under mostly cloudy to cloudy skies.
Convective coverage will be hard to pin down for Saturday, with
differential heating and instability best in the southeast part, but
possibly more lingering boundary interaction in the northwest half,
and returning SE upslope flow affecting the Blue Ridge late day.
Instability could become very robust on Saturday afternoon, with
some 2000 to 3000 J/kg sbCAPE possible with any heating given the
high dewpoints in the 60s and slightly cooling temperatures aloft
ahead of the central CONUS trough. Strengthening mid-level flow will
permit deep layer shear to gradually increase through the period,
but speeds in the lower 3 km of the atmosphere should not get
especially impressive until just past the near term.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 300 PM EDT Friday: The focus of the short term period remains
the potential for severe weather on Sunday, currently highlighted by
the SPC Enhanced Risk that extends well into the CWFA, encircled by
the Slight and Marginal Risks that cover the balance of the forecast
area.
There remains little doubt that a very good dynamic set-up for
severe weather will be in place Sunday. A deep upper trough will
pinch off over the deep south and encourage rapid surface
cyclogenesis later during the day on Saturday. The low will
translate rapidly northeast Saturday overnight, placing our area
squarely in the warm sector on Sunday. Stout low-level southeasterly
flow will allow surface dew points to increase to the mid 60s, and
temperatures will likely rise to the low to mid 70s across the SC
Upstate and NC/SC Piedmont. There will likely be an ongoing band of
convection oriented north-south moving into the forecast area late
Sunday morning, and though destabilization will likely not have much
time to occur by that point, modest CAPE of ~500 J/kg in the far
eastern portion of the forecast area may be all that is needed to
maintain the line into our area. Deep layer shear will be quite
plentiful, and re-invigoration of the line will be likely through the
afternoon. Low-level (0-1km) directional shear isn`t fantastic, and
lack of really good instability will probably support more of a
cluster/linear storm mode rather than discreet cells. It does seem
that the eastern portions of the forecast area will be able to
destabilize more by Sunday afternoon than the rest of the area, and
if the current numerical guidance is correct, ~1500 J/kg of SBCAPE
could be realized by 18-21Z in the eastern SC Upstate and NC
Piedmont. Around this same time, southerly 850mb flow will increase
to 50kt+ in the eastern half of the forecast area, enhancing already
impressive deep-layer shear profiles in the most unstable areas. All
severe threats are still in play at this point, though the expected
linear mode would suggest the largest threat will be for damaging
winds. There is still some question as to destabilization with a
previous frontal boundary laying over the forecast area Saturday
through early Sunday and maintaining at least good cloud cover, if
not some scattered ongoing convection. Though uncertainty in the
details remains, this system is quite impressive, and bears a close
watch.
A quick note on a flash flood threat with this system on
Sunday...convective rain rates will likely be very impressive with
the line, and depending on how much rain falls on Saturday and the
rates that are realized Sunday, an isolated flash flood threat could
materialize across the forecast area. This will be watched as well,
though high confidence in any flooding will likely be absent until
Sunday afternoon.
Finally, most of the severe convection should clear the area by soon
after 00Z Monday, though some rain and showers could linger. The
front itself will move quickly through overnight, with no pops
remaining by Monday morning.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 245 PM EDT Friday: With the trough axis moving to the east,
upper-level convergence will support a high pressure system
propagating east Monday evening with a 1020-1024 mb centered
in our region by Tuesday morning. This will set up a gorgeous
Tuesday and Wednesday across our area as the upper-level ridge
axis moves overhead by Wednesday morning. High temperatures will
remain warm, running about 1-3 degrees above normal on Tuesday
and about 4-6 degrees above normal on Wednesday with widespread
70s across the mountain valleys and points east. The lower SC
and GA Piedmont may reach 80 on Wednesday. Dewpoints across the
area will be very pleasant both days, in the low 40s on Tuesday,
increasing into the upper 40s to lower 50s on Wednesday as return
flow starts on the backside of the clockwise circulation. If you
are looking to take a day or two off of work to enjoy the outdoors,
this is your opportunity!
The next significant weather maker ejects into the Plains for
Thursday as a broad and deep longwave trough amplifies and a ~540dm
500mb closed-low is progged to move into the Midwest by Thursday
night. Upslope flow shower chances are expected to increase
during the day on Thursday as moist southerly flow strengthens.
Despite mostly cloudy skies, highs will be similar to Wednesday
within the warm sector but with higher dewpoints (upper 50s)
in the return flow. The dynamics ahead of this system suggest
another period of active weather for our area as the attendant
cold front marches east across the Tennessee Valley while the
sub-1000mb surface low pressure system occludes over the Midwest.
As discussed in the previous package, being 6+ days out there
remains plenty of uncertainty in the timing and the overall
environment over our area. A blend of the available guidance
forecasts a frontal passage later during the day next Friday,
suggesting the best combination of forcing and instability will
occur over the Piedmont. However, if the front passes through
overnight, peak forcing will not coincide with peak instability.
Nevertheless, with 0-3km bulk shear values in excess of 50 kts
and 0-6km values in excess of 70kts within favorable diffluent
flow, we will have to watch guidance evolution closely next week.
Furthermore, a nose of 1.5"+ precipitable water values suggest
deep moisture will briefly move into the region Thursday night
into Friday afternoon ahead of the front as it moves through the
region so any convection will produce heavy downpours that may
cause significant runoff. Regardless, it`s spring and the pattern
will act like it, with falling heights associated with the closed
low suggesting cooler temperatures by Saturday.
&&
.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
At KCLT and elsewhere: Despite lingering instability around KCLT,
things have been fairly quiet so far early this evening. There is
line of convection well to the south, that looks to track just east
of KCLT later this evening. So will go with a convection-free TAF
thru 06z. From there, guidance in good agreement that another round
of mainly shallow showers will develop across the area, as a weak
front drops south and stalls across northern NC. Moist southerly
flow atop the frontal zone will produce expanding low cigs and
showers thru the overnight, peaking around 12z. The front begins to
lift back north and light southerly flow will persist. But there
should be a lull in showers and a gradual mixing/scattering of the
low cigs by early Saturday aftn. Just enough breaks in the clouds
may help destabilization and a few TSRA to develop. Will go with
VCSH for the early morning convection, then PROB30 for SHRA/TSRA
during peak heating hours Saturday. Sfc winds will be light, mainly
south to southeast, except N at KAVL late tonight thru midday
Saturday.
Outlook: A strong cold front will approach the area Sunday to
produce the potential for stronger thunderstorms and wind gusts.
Continued restrictions are highly likely from Saturday night into
Sunday night ahead of and along the front. VFR conditions should
return early next week behind the cold front.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 89% Med 76% High 81% High 100%
KGSP High 100% Med 79% High 89% High 100%
KAVL High 100% High 83% High 94% High 100%
KHKY High 84% Med 77% High 87% High 100%
KGMU High 100% Med 69% High 86% High 100%
KAND High 100% Med 76% High 82% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...JMP
NEAR TERM...ARK/HG
SHORT TERM...Carroll
LONG TERM...JMP
AVIATION...ARK
Area Forecast Discussion
National Weather Service Wilmington NC
1010 PM EDT Fri Apr 12 2019
.SYNOPSIS...
Warm and humid weather will continue through the weekend
with scattered showers and isolated thunderstorms. Low pressure
across the Great Lakes will send a cold front across the coast
late Sunday and early Monday with strong to severe thunderstorms
possible. Dry high pressure will follow through mid week. A
cold front will cross the Carolinas late Thursday through
Friday.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
As of 930 PM Friday...Adjustments made to overnight POPs
based on latest 88D trends and HRRR output. Basically have 2
convergent areas working their way very slowly eastward. And
eventually will become 1 convergent area that will eventually
work it`s way east of the FA toward daybreak. The threat for
thunder has pretty much diminished with the loss of daytime
heating. And the dynamics associated with these convergent
boundaries not strong enough alone to produce thunder. As a
result, will indicate mainly RW- for the remainder of this
evening and overnight. The sfc pg does relax-some overnight
but enough should keep SE-S winds active enough to minimize
widespread or even areas of fog. Will have to keep an eye on
possible patchy sea fog that may develop especially if sfc
dewpoints reach the upper 60s during Sat as winds becoming
more southerly. It still may be difficult for sea fog to
develop given latest SSTs having climbed into the mid 60s attm.
Very little if any tweaks applied to tonights lows.
Previous.......................................................
As of 300 PM Friday...Rich low-level moisture (by mid April
standards) is advecting onshore as a weak NW-SE oriented warm
front weakens across southeastern North Carolina. This front has
remained the focus for persistent clouds and showers today and
is also identifiable by a 3-5 degree dewpoint difference and a
30 degree wind convergence axis. Rain has yet to fall east of
the front at Wilmington or Topsail Island where lower dewpoints
have kept surface parcels stable. West of the front across much
of eastern South Carolina SBCAPE has risen to between 1000-2000
J/kg, but convective showers have been limited in
coverage/intensity by a gradually weakening mid-level cap and
substantial dry air aloft. A ribbon of deeper moisture
approaching the I-95 corridor by 5 PM should support
thunderstorms and possibly gusty winds.
Inland convective activity appears to be largely supported by
surface-based instability and should tend to dissipate after
sunset. High-res convection-allowing models suggest there will
be a resurgence of maritime convection overnight south of Cape
Fear along the remnant front. Mid-level winds would advect any
activity on to the beaches near and north of Cape Fear, where
I plan to hang on to higher PoPs overnight. Some patchy fog
could develop overnight, and lows should only fall to 65-67,
easily 15 degrees above normal.
The old warm front should be toast by Saturday morning and a
straight south wind is forecast across the area. The airmass
should be even a little warmer aloft, supporting inland highs
in the lower 80s, with some 70s within a few miles of the
beaches. SBCAPE should again rise to 1000-2000 J/kg, supporting
scattered showers and thunderstorms. Although multiple upper
level impulses will move northeastward across the western
Carolinas throughout the day, our convection should continue to
be mainly diurnal and will develop along local boundaries and
outflows. Forecast PoPs Saturday range from 30 percent along the
coast to 50 percent west of I-95. Convection should largely die
away Saturday evening with partly cloudy conditions overnight.
Saturday night`s lows in the mid to upper 60s will again be 15+
degrees above normal for the date.
&&
.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...Warm and humid air mass in place
ahead of approaching cold front on Sunday. Should be a quiet
day to start as soundings show a deep dry layer aloft above h7,
but this will change later in the aftn as air mass destabilizes
more ahead of a cold front. Dewpoint temps will be in the mid
50s with strong LLJ up to 60 kts. The gradient will tighten with
increasing southerly sfc winds becoming gusty through the
afternoon. Aside from a stray shower early on, the main activity
will ride up through the central Carolinas late aftn and will
move eastward into the evening hours as deep mid to upper trough
drives it toward the coast. SPC has the strongest severe
potential west of local forecast area, but a marginal risk cuts
through out CWA with a slight risk closer to the coast. Overall
expect showers and thunderstorms to increase through late Sunday
weakening some as they reach the coast by late evening.
Showers will diminish overnight and by daybreak model soundings
show a deep dry air mass in places. Pcp water values drop from
near 1.75 Sun eve down close to half inch after daybreak Mon
morning in deep cooler and drier westerly flow on the back end.
Temps up near 80 on Sun will remain warm through Sun night but
will begin to cool and dry heading into Monday.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 300 PM Friday...Ridge of high pressure will build in
behind exiting system through Mon into Tues. Deep W-NW flow
will bring unseasonably cool and dry weather Monday through
Tues with plenty of Sunshine. Temps will reach into the 70s
with overnight lows down to 45 to 50 most places.
As the high shifts off the coast by Wed a return flow will set
up with a warmer and more humid air mass returning. Expect
sunshine through Wed, but should see some cu building by Thurs
and potential for showers and thunderstorms by Fri as a cold
front marches through the Carolinas from west to east. Should
see some stronger storms with this system. Temps will warm into
the 80s most places Wed through Fri with overnight lows on the
warm side, remaining in the 60s.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
As of 0Z....Sub-VFR conditions to prevail through tomorrow
morning as southerly flow ahead of stalled cold front to our
west advects moisture into the region. Widespread MVFR ceilings
will develop over the next few hours, with good chance for IFR
ceilings for few hours early tomorrow morning. Not expecting
widespread visibility restrictions, but brief MVFR vsbys are
possible tomorrow morning at all terminals. As far as
precipitation is concerned, models are indicating showers will
be pretty scattered into early tomorrow afternoon and chances of
rain at a particular terminal is hard to pinpoint. Have kept
rain out of TAFs, but there is chance of rain at all terminals,
particularly ILM, through tomorrow afternoon. Current southeast
winds will become southerly overnight through end of TAF period.
Extended Outlook...Showers possible both Saturday and Sunday,
with isolated strong TSTMs possible late Sunday. VFR Monday
through Wednesday.
&&
.MARINE...
As of 945 PM Friday...Have extended the SCA forward by 1/4 to
1/2 day due to seas being the culprit and taking slightly longer
to drop below SCA thresholds. This a result of the decent SE-S
fetch of the past 1-2 days. The sfc pg will generally be slowly
relaxing-some thru the overnight period with winds overnight
generally diminish to SE around 15 kt north of Cape Fear and S
to SSE 10-15 kt south of the Cape.
Will have a few convergent boundaries over the waters that
produce showers late this evening that will eventually coalesce
into 1 convergent boundary of showers that occasionally move
northward and onshore from Cape Fear to Surf City during the
overnight period.
Previous.................................................
As of 300 PM Friday...High pressure retreating away from the East
Coast has led to a solid southeast breeze across the area over
the past 24 hours. A warm front off Georgia yesterday has
lifted almost to Cape Fear this afternoon. This boundary should
weaken and eventually dissipate as winds veer more southerly
overnight. The strongest period of winds is already behind us,
and speeds should diminish to only 10 knots after midnight. Seas
still averaging 6 feet nearshore in the Cape Fear area at last
check should gradually subside overnight into Saturday. The
Small Craft Advisory will be allowed to expire at 3 AM along the
South Carolina coast, and at noon Saturday along the North
Carolina coast when the last of the six-foot seas should
dissipate at 20 miles from shore.
Showers have largely dissipated across the coastal waters this
afternoon, but are expected to redevelop overnight. Showers and
even a few thunderstorms are expected to be most numerous near
the dissipating warm front in the Cape Fear area. Showers should
diminish again Saturday as a classic summertime seabreeze front
moves inland during the daylight hours, taking most of the
convection inland with it.
Southerly winds will increase through Sunday with the approach
of a cold front. Winds and seas will increase rapidly to
advisory levels late Sun aftn into the eve. WNA showing winds up
to 25 to 30 kts with higher gusts and seas up to 8 to 10 ft in
the outer waters. Winds will veer around to the W after midnight
as cold front crosses the waters.
Winds will veer around more on Mon as high pressure builds in,
diminishing down to 5 to 15 kts by Mon eve. Marine conditions
will be quiet Tues into Wed as light northerly flow becomes more
variable as high pressure moves closer overhead. Seas should be
less than 3 ft Tues aftn through Wed. A southerly
return flow will develop as high pressure shifts off the coast
Tues night into Wed, remaining light through early Thurs.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...High Rip Current Risk from 6 AM EDT Saturday through Saturday
evening for NCZ106-108.
MARINE...Small Craft Advisory until 6 AM EDT Saturday for AMZ254-256.
Small Craft Advisory until noon EDT Saturday for AMZ250-252.
&&
$$
SYNOPSIS...
NEAR TERM...DCH/TRA
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...VAO
MARINE...
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1131 PM EDT Fri Apr 12 2019
.UPDATE...
Issued at 1131 PM EDT FRI APR 12 2019
Temperatures have cooled off into the lower 50s west of I-75,
where high pressure is currently centered, and where some
relatively thinner high clouds reside aloft. Adjusted lows down
somewhat for these areas; however, thicker high clouds should move
back in overnight, thwarting much more of a drop off. Have made
some minor adjustments to the hourly temperatures and dew points
elsewhere to account for the trends in observations. The rest of
the forecast generally remains on track.
UPDATE Issued at 847 PM EDT FRI APR 12 2019
The surface cold front has worked its way east of the area, with
shower and thunderstorm activity ceasing. Some of the model
guidance continues to indicate a few showers possibly threatening
far southeastern Kentucky after midnight. Did delay these PoPs a
bit longer per the latest runs of the HRRR and NAM. Clouds will
also likely hang tough tonight, with deep southwest flow remaining
in place at the mid and upper levels of the atmosphere. The
forecast lows look reasonable. Did readjust the diurnal curve a
bit through this evening, as some locations were dropping off a
a little quicker than forecast. Updates have been sent.
&&
.SHORT TERM...(This evening through Saturday night)
Issued at 342 PM EDT FRI APR 12 2019
A slow moving front continues to slow down as a deep low pressure
system over the northern plains occludes. This boundary has
interacted with some instability to yield a few isolated showers
and storms across portions of the area this afternoon. As this
instability weakens this evening, I expect much of the shower
activity to diminish. There is a chance a few showers could try to
get going overnight, so have kept a 20 percent chance of a shower
across southeast Kentucky tonight as the boundary continues to
stall out. A difficult cloud/temperatures/fog forecast tonight as
the front stalls out we may keep at least some mid to high cloud
around through the night. This could help keep temperatures from
cratering. We also have dry advection north and west of the
stalling out boundary, and this is the area more likely to see
some clear skies tonight. Thus, hard to pinpoint where conditions
may be most favorable for fog tonight as we have some favorable
and non-favorable conditions. Thus, going to hold off on
introducing any fog into the forecast and let the evening shift
evaluate the need to add any fog. Temperatures will also be very
dependent on where skies can clear, but will settle for low to mid
50s for most areas. Valley locations could end of colder if skies
can clear out.
Tomorrow, an upper level trough will move into the southern
plains/Mississippi river valley region. Low level southeast flow
will strengthen through the day. Given the downslope flow
conditions, dry conditions will likely hold over the area despite
the stalled frontal boundary lifting northward. With the downslope
flow, opted to go milder for highs on Saturday with readings into
the mid 70s. Dewpoints will also be quite low with MET/MAV
guidance suggesting dewpoints could be between 37 and 42 across
much of the area. This is much lower than inherited forecast, but
does seem to make sense given the setup. This may put afternoon
RH`s down under 30 percent, but surface winds should remain light
enough to limit the fire danger.
By Saturday night, the mid level trough axis will shift east and
north towards the Ohio river valley with the eastern CONUS ridge
amplifying. This will provide very mild conditions across the area
Saturday night. Rain chances will likely hold off until very late
as the flow will remain too southerly to allow much moisture
return. Will bring in some slight chance to chance pops towards
dawn to account for the approaching system.
.LONG TERM...(Sunday through Friday)
Issued at 445 PM EDT FRI APR 12 2019
The main forecast concern this period is with the potential for
strong to severe convection Sunday afternoon to Sunday evening.
The period is expected to begin with a mid and upper level trough
approaching the area from the west with ridging over the Atlantic
and another ridge extending into the southwest Conus. A deepening
sfc low is expected to be tracking across the Lower OH Valley to
begin the period with a warm front lifting north of the area and
the region getting into the warm sector. There is some model
variability in the strength and timing of the upper trough as it
moves east as well as the strength of the sfc low tracking into
OH. The 12Z NAM is stronger with the sfc low compared to the 12Z
ECMWF and 12Z GFS runs by 0Z Monday. The 12Z NAM is also a bit
slower with the cold front compared to much of the other guidance.
Some convection may be ongoing on Sunday morning per model
guidance with a midday lull in activity and the likelihood of
some destabilization by mid afternoon. Wind shear will be rather
strong with this system and more speed shear versus directional
shear. The degree of instability is also uncertain with the GFS on
the lower end nearer to 500 J/KG or less with the NAM runs more
significant, but the wind fields suggest at least linear
convection potential with strong to damaging wind gusts the
primary threat. If more instability can be realized, some hail
would also be possible. Moisture will also be sufficient enough
for locally heavy rain, especially in locations that experience
multiple thunderstorms. Within any lines or line segments, a QLCS
tornado cannot be ruled out as well. SPC has placed the region in
an enhanced risk for severe thunderstorms for this. The cold front
should move across the region during the evening, with the threat
for severe convection diminishing before midnight. However, the
threat for showers should linger into early on Monday as the upper
level trough moves into the Appalachians.
Height rises in the mid and upper levels and sfc high pressure
building into the region should lead to a period of drier weather
from Monday afternoon into the middle of the week. Temperatures
during that period will also be cooler than what has been
experienced recently with most locations not expected to climb out
of the 50s on Monday. Dewpoints may be sufficiently dry for a few
southeastern valley locations to experience some patchy frost on
Monday night as good radiational cooling should occur as the sfc
high slides into the Appalachians.
Unsettled weather should return during the second half of the week
as the next in a series of upper lows moves from the Rockies and
in the Plains at midweek and then tracks into the Great Lakes by Thu
night and Friday. The associated cold front should approach East
KY on Thu and move across the area by Friday morning while the
axis of the mid level through should approach the area on Friday.
Showers will be possible at times, with the highest chances as the
cold front moves through when thunderstorms are also most
probable.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
ISSUED AT 847 PM EDT FRI APR 12 2019
High pressure will gradually build in across the Ohio Valley, with
VFR conditions prevailing across eastern Kentucky. Mid and high
level clouds will be prevalent through the period, although some
higher based cumulus ranging from 5-7k feet agl will also be seen
at times. West to west northwest winds of around 5 kts will turn
light and variable this evening, before becoming more east
northeast at around 5 kts by late Saturday morning.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...GEOGERIAN
SHORT TERM...KAS
LONG TERM...JP
AVIATION...GEOGERIAN
Area Forecast Discussion
National Weather Service San Francisco Bay Area
829 PM PDT Fri Apr 12 2019
.SYNOPSIS... A beautiful weekend is forecast with mostly sunny
skies and temperatures in the 60s and 70s. Cooler temperatures are
expected early next week with a chance of rain primarily on
Monday. A robust warming trend with dry conditions develops later
next week.
&&
.DISCUSSION...as of 08:02 PM PDT Friday...If you liked today`s
weather it was just a preview of Saturday. Building high pressure
today started a noticeable warming trend around the Bay Area.
Today`s warmest temperatures were felt across the interior as with
highs reaching the low to mid 70s. A weak onshore flow kept the
coast and Bay Shoreline cooler and mostly in the 60s, a few spots
along the immediate coast stayed in the upper 50s. It`s still a
little breezy, especially over the hills, but much less in the way
of wind than earlier today.
For tonight, latest hi-res models like the HRRR and WRF still show
a possibility of patchy coastal stratus. Current forecast does
bring in some coastal low clouds and at this point see no reason
to remove them from the forecast. Impacts will be minimal if any.
Any Saturday morning clouds will be shortlived as high pressure
currently off the coast builds inland. Mostly sunny skies will
prevail with an overall warming of 2 to 7 degrees across the
region. The most notable warming will be across the interior with
highs in the 70s to possible low 80s. Coastal area will still feel
a little ocean influence limiting potential, but highs in the 60s
will be pleasant. In context of climatology, Saturday`s high
temperatures will be a few degrees above normal for April.
Short term weather looks to remain on track and no update is
needed.
Temperatures will cool slightly on Sunday as the ridge flatten due
to an approaching upstream system. Latest 00Z NAM still indicates
a return of unsettled weather with precip moving through the
region on Monday. Will need to wait for the rest of the 00Z suite,
but rain on Monday is looking more likely.
&&
.PREV DISCUSSION...as of 03:00 PM PDT Friday...
Saturday should be a beautiful day with mostly clear to partly
cloudy skies, a slight to locally moderate warming trend over
today, lighter winds, especially away from the coast, and dry
conditions.
The influence of the ridge will weaken on Sunday as predominately
quasizonal to weak WNW flow develops aloft -- heralding a return
of near neutral/normal conditions for the region. Periods of more
unsettled weather will occur during this timeframe in response to
a series of disturbances of varying strength will pass near and to
the north of the area. The most impactful of these disturbances
arrives between late Sunday night through early Tuesday morning
and will bring with them a slight chance to chance of light rain
showers for most of the region. Due to the fact this is a series
of weaker impulses rather than a more organized single storm
system, there exists some uncertainty regarding the exact timing
and coverage of any rain during this time frame. Total rain
accumulations should remain close to a few to several hundredths
for most areas, though a few of the wettest showers could bring up
to 0.10-0.15" for localized portions of the North Bay.
Then, a more robust warming trend is expected to set up late next
week. Models have been showing increasingly warm temperatures with
each model run, particularly on what is expected to be the hottest
day next week -- Thursday. This is not unusual with anomalously
warm events that push beyond certain thresholds as the models have
a tenacity to underforecast more highly anomalous events due to
their bias towards a steady state and previous events (in which
most are not highly anomalous). As a result, we as forecasters
generally nudge the data slightly higher once we approach standard
deviations of around 2.5-3.0. The latest confidence toolkit data
(an internal tool we use to analyze anomalous patterns) indicates
a +2.9-3.1 std temperature anomaly meaning that we should expect the
forecast model data to underestimate the true conditions. As
such, the latest forecast package has been nudged slightly upward
over raw blended model output. The forecast data may continue to
increase as the strength of the ridge and timing of the ridge apex
comes into better focus of the shorter term, higher resolution
models. As such, can not rule out temperatures on Thursday pushing
into the upper 80s or even around 90 for the warmest inland
locations. Elsewhere, expect inland temperatures in the low to mid
80s, and widespread upper 60s to upper 70s along the coast.
Friday will be slightly cooler near the coast but could be even a
tad warmer farther eastward/inland, depending on the timing of the
ridge. Either way, stay tuned as the extended forecast comes into
better focus!
&&
.AVIATION...as of 5:12 PM PDT Friday...VFR except MVFR visibilities
in spots along the immediate coast due to patchy haze. Sea surface
temperatures (SSTs) aob April normals per recent upwelling, buoy
reports SSTs ranging from 51 F to 54 F; visible sat imagery shows
a few stratus patches vicinity Monterey Peninsula to Point Sur
otherwise it`s clear.
The 18z NAM initialized pressure gradients well, but the NAM/WRF/HRRR
surface and boundary layer relative humidity fields were initialized
too high and continue over-forecast at the current hour. Low to mid
level thermal and height ridging generally increases through the
period thus increasing stability with surface winds decreasing by
mid evening. Scaled back a bit, but still leaning the 00z KMRY and
KSNS tafs toward possible patchy coastal stratus nearby the terminals
early Saturday morning, otherwise terminal forecasts are near high
confidence VFR. Light E-SE winds developing tonight due to relaxation
of surface pressure gradients and weak cool air drainage in the
valleys under clear skies carry over into the morning hours before
onshore winds resume by late Saturday morning and afternoon.
Vicinity of KSFO...VFR, west wind 20 to near 30 knots until 04z
then decreasing onshore wind through late evening. Light/variable
wind Saturday morning, onshore wind returns near noontime, a few
gusts to 25 knots beginning by 22z Saturday. Onshore winds decreasing
again by 04z Saturday evening.
SFO Bridge Approach...Similar to KSFO.
Monterey Bay Terminals...VFR, west wind 10 to 15 knots til mid
evening then decreasing and becoming light/variable then light
E-SE overnight. Light E-SE wind in the morning becoming onshore
near 10 knots Saturday afternoon and early evening. A few patches
of stratus possible early Saturday morning otherwise moderate to
high confidence VFR.
&&
.MARINE...as of 4:40 PM PDT Friday...Strong high pressure over
the eastern Pacific will keep gusty northerly winds in place
through much of the weekend. These winds will result in small
craft advisory conditions with steep wind waves and fresh swell.
An upper level system will then move through the region on Monday
gradually turning winds southerly across the coastal waters. Light
to moderate northwest swell will continue through the forecast
period.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.Tngt...SCA...Pigeon Pt to Pt Pinos 0-10 nm until 3 AM
SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 AM
SCA...Pt Arena to Pt Reyes 0-10 nm
SCA...Pt Arena to Pigeon Pt 10-60 nm
SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
SCA...Pt Reyes to Pigeon Pt 0-10 nm
SCA...Mry Bay until 9 PM
&&
$$
PUBLIC FORECAST: MM/DRP
AVIATION: Canepa
MARINE: AS
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/nwsbayarea
www.twitter.com/nwsbayarea
www.youtube.com/nwsbayarea
Area Forecast Discussion
National Weather Service Nashville TN
901 PM CDT Fri Apr 12 2019
.UPDATE...
FOR EVENING DISCUSSION.
&&
.DISCUSSION...
Radar this evening is showing a band of light rain stretching
from northern Alabama northeastward across the Plateau counties
then into eastern Kentucky. This activity appears to be
associated with the 850mb cold front which has stalled out due to
the approaching upper trough over west Texas. Overnight, this
front and the surface stationary boundary will begin returning
northward as the upper trough progresses further eastward. Lift
along the boundary will promote development of additional showers
and a few thunderstorms especially over our southwestern
counties. Have adjusted pops based on the latest CONSShort and
HRRR models. This activity should move out of Middle Tennessee
Saturday morning, and majority of guidance keeps much of the area
dry on Saturday afternoon and evening prior to a line of strong
or severe thunderstorms moving through late Saturday night.
Uncertainty remains on both timing and strength of the Saturday
night activity. Some 18Z models move this line of storms across
the Tennessee River as early as midnight Saturday night, while
others are much later towards sunrise on Sunday. As far as
intensity, MUCAPE will be on the low side at around 600 J/Kg or
less, but shear will be very strong and likely enhanced due to a
strengthening sub-1000mb surface low depicted moving
northeastward across western TN/KY. Based on all of this,
damaging winds and a couple of tornadoes appear possible in the
overnight hours Saturday night, with the best chance across our
southwestern counties where MUCAPE will be highest. Regardless if
severe weather occurs with this event or not, it`s a good
reminder that April is the most likely month for tornadoes across
Middle Tennessee - so know your safe place to go ahead of time to
keep you and your family safe in case of severe weather.
&&
.AVIATION...
00Z TAF DISCUSSION.
Expecting VFR conditions over the TAF period, with showers
possibly bringing brief MVFR cigs at KCSV overnight. Showers look
to move in after 05Z and will impact all terminals before the late
morning hours. Additional chances for showers and a few
thunderstorms will be possible during the afternoon and evening.
Winds will transition to be more easterly around 10 knots gusting
up to 20 knots at times for KBNA/KMQY/KCKV by the afternoon, and
around 10 knots at KCSV.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......Shamburger
AVIATION........Barnwell
Area Forecast Discussion
National Weather Service Pueblo CO
922 PM MDT Fri Apr 12 2019
.UPDATE...
Issued at 911 PM MDT Fri Apr 12 2019
Showers rather slow to get going this evening, with best coverage
of rain/snow along the NM border and near the Palmer Divide. Last
few runs of the HRRR and 00z NAM are rather skimpy with precip
overnight, especially over the Sangres where pocket of low/mid
level dry air will be tough to overcome. On the plus side, soundings
are at least weakly unstable with upward motion over the area
through the night, though low level upslope flow wanes toward
morning. Overall, suspect heavier snow accums will be spotty
overnight, though a few convective bursts over the mountains,
Palmer Divide and ern plains south of the Arkansas River county
could lay down a quick couple of inches. In light of the downward
trend in precip chances, began to lower pops and qpf at many
locations overnight, with only minor tweaks to other portions of
the forecast.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 337 PM MDT Fri Apr 12 2019
...Light to moderate snow accumulations in and near the mountains
next 24 hours...
Upper low taking shape across the desert southwest will move across
New Mexico into southwest Texas by Saturday morning, while the
northern stream extension of the upper trof drags across CO on
Saturday. Models show a warm air advection band of precipitation
taking shape across southern portions of the southeast plains this
evening which lifts northward during the overnight and early morning
hours. Shallow easterly upslope flow will help to spread low stratus
back westward into the southeast mountains with some light snow
showers expected across the plains by morning as temperatures drop
below freezing. Warm ground and lack of any wind should mitigate
impacts some for the lower elevations...with area most at risk for
heavier accumulations across the southern Sangre De Cristo mountains
and possibly into portions of the southern I-25 corridor from
Walsenburg to Trinidad. QPF fields from models are muddied up by
convective enhancement and leaned more towards a ECMWF/GFS blend to
reduce some of this effect. Of course NAM with its convectively
overdone QPF does indicate the potential for some local snow bursts
with the convective snow showers in the afternoons. So given the
suite of guidance have hoisted winter weather advisories for the
southern Sangre De Cristo mountains, as well as the higher peaks
above 10-11kft of the northern Sangre De Cristos, Wets and Pikes
Peak. Getting 4 to 11 inches of snow for these areas. Best lift
though will focus to the south...and am somewhat concerned that the
southern I-25 corridor counties (western Las Animas and Huerfano
counties) could see some pockets of advisory level snow amounts over
the next 24 hours. Given lack of sustained upslope...will refrain
from adding them into advisories for now. But as always, convection
provides a wild card that can be difficult to account for with
spring snow events like this one. Will just have to play this by
ear.
Activity should decrease some Saturday morning and weaken as it
lifts off to the northeast. However with the upper trof axis moving
across, there will still be plenty of moisture and instability for
another round of convective higher elevation snow showers in the
afternoon and evening over the mountains. Majority of POPs will
pull westward to locations in and near the mountains for the
afternoon hours. Temperatures on Saturday will remain below climo.
-KT
.LONG TERM...(Saturday night through Friday)
Issued at 337 PM MDT Fri Apr 12 2019
Saturday night-Sunday...Moderate northwest flow aloft across the
region Saturday night becomes more westerly through the day Sunday,
as Saturday`s quick moving upper trough continues to translate east
and flat upper level ridging builds across the Rockies. Isolated to
scattered showers over and near the higher terrain late Saturday
afternoon will quickly diminish through the evening with clearing
skies into the overnight hours, as the subsident northwest flow
takes hold. After another cool night, with lows in the teens and
20s areawide, warming aloft and downslope flow will help boost
temperatures back to at and above seasonal norms on Sunday, with
highs in the 60s to lower 70s across the Plains, in the 40s and
50s across the higher terrain and in the 30s at the peaks. Latest
models do indicate a minor embedded wave moving across the Northern
Rockies through the day, though looks to keep best precipitation
chances north of the area, and have kept only slight pops in tact
across the higher elevations of the Central Mountains Sunday
afternoon.
Sunday night-Tuesday...West to southwest flow aloft progged to
increase Monday into Tuesday, ahead of a Pacific upper trough
digging across the Great Basin through the day Tuesday. Increasing
downslope flow will again boost temperatures back to above seasonal
levels on Monday, with breezy downslope winds leading to the potential
for critical fire weather conditions across portions of the Southeast
Plains Monday and again on Tuesday. Dry weather across the area on
Monday will give way to increasing chances of showers across the
higher terrain through the day Tuesday, with the best coverage along
and west of the Continental Divide.
Tuesday night-Friday...Another cool and unsettled weather pattern
expected through the middle of next week, as latest models continue
to move this system across the area Tuesday night and Wednesday,
bringing rain and higher elevation snow, to the area once again.
This system remains relatively warm, as snow levels lower to
between 7000-9000 feet Tuesday night, with north to northeast
upslope flow behind the systems passing cold front providing
enough lift for possible winter weather highlights across the
Southeast Mts and higher elevations along the Raton Mesa into
Wednesday morning. Cool and unsettled weather then continues
through Thursday, as secondary energy is progged to dig down the
backside of the system before warmer and drier weather takes hold
for the end of next week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 337 PM MDT Fri Apr 12 2019
Patchy MVFR cigs this evening will gradually lower into the IFR to
LIFR categories after midnight for both KCOS and KPUB. Convective
showers will be possible this afternoon and early evening with a
brief break before more persistent showers spread in after midnight.
A switch over to snow is expected at both terminals with some light
accumulations of an inch or two possible on grassy surfaces. Low
clouds will be slow to break on Saturday but should see rising
ceilings in the afternoon with KCOS and KPUB likely staying in the
BKN MVFR category into early Saturday evening. KALS will remain
predominantly VFR though cigs could approach high end MVFR with VCSH
Saturday afternoon. Winds at all three terminals will become light
this evening and remain under 15kts through Saturday. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 PM MDT Saturday for COZ073>075-
080-082.
&&
$$
UPDATE...PETERSEN
SHORT TERM...KT
LONG TERM...MW
AVIATION...KT
Area Forecast Discussion
National Weather Service Shreveport LA
944 PM CDT Fri Apr 12 2019
.UPDATE...
As expected, scattered showers and a few thunderstorms are
beginning to develop near and to the south of the Interstate 20
Corridor of NE TX and N LA in an area of isentropic lift. The warm
front still remains well south of our region this evening but this
activity is associated with increasing low level flow with KSHV
VAD Winds already peaking at near 35kts which is nearly double
from just 6 hours ago.
Of interest with the latest 00z NAM12 output is an area of
convection the model develops late tonight across Deep East Texas,
moving this feature northeastward into NW LA towards sunrise.
Can`t depict anything out in the strengthening southwest flow
aloft pattern so this could be some feedback in the model but the
fact that the HRRR is also depicting something similar, albeit not
as strong or widespread, is a bit concerning. Did notice that the
progs are a little slower moving the 850mb front northward
overnight into our region which may cut down on the widespread
rainfall the models were depicting earlier across our northern
most zones by sunrise. All this to say, beefed up pops slightly
across Deep East Texas into NW LA in the 06z-12z timeframe. These
storms could pose a hail threat overnight given that they will
likely be elevated with the true sfc based tornado/wind threat not
likely to materialize until we get the warm front and warm sector
into our region from the south during the day Saturday.
Did adjust temps slightly overnight as 02z temps were very close
to fcst mins in the morning, especially across our eastern zones
who have experienced some rainfall this evening. Otherwise, no
significant changes were made to the remaining portions of the
forecast.
Updated forecast package out shortly...13.
&&
.PREV DISCUSSION... /issued 550 PM CDT Fri Apr 12 2019/
AVIATION...
Currently tracking scattered convection in the vicinity of the MLU
terminal that is moving northeast attm. An elevated 850mb boundary
will be moving northward overnight that will trigger additional
scattered convection near and to the north of the I-20 terminals
so have accounted for this possibility in the 00z TAF set.
Otherwise, the big story will be the severe convection expected
to impact our terminals during the day Saturday. MVFR ceilings
will return to most terminals late tonight with VCTS through the
mid morning hours. Introduced prevailing TSRA during the daytime
hours on Saturday for all terminals and as a sfc low begins to
eject out of Central Texas late Saturday Morning through the
afternoon hours, gradient winds in the warm sector ahead of the
northeastward moving low will get cranking with sustained winds
near 20kts with gusts upwards of 30kts. Obviously convective winds
have the potential to become much stronger but for now, have left
these kind of gusts out of the 00z terminal package. Winds will
quickly veer around from an easterly direction to a southerly
direction on Saturday, especially across our NE TX terminals with
a northwesterly directional wind shift not expected until just
beyond this 00z TAF package.
13
PREV DISCUSSION... /issued 331 PM CDT Fri Apr 12 2019/
SHORT TERM.../Tonight through Saturday Night/
Clouds to increase from the south overnight as a warm front lifts
north across the ArkLaTex. Southerly flow behind the warm front
will advect increased moisture across the region with dewpoint
values forecast to climb into the mid to to upper 60s on Saturday.
Also, an enhanced surface pressure gradient will generate south
winds around 15 to 20 MPH by mid-morning Saturday. Mid to upper-
level trough translating east across Texas will merge with frontal
boundary allowing for deep-layer sheer to increase throughout the
day on Saturday. Additionally, with steep lapse rates,
instability will be sufficient to allow for rapid intensification
of storms. Severe weather threat will increase during the day,
climaxing during the time of max surface heating and continuing
through the evening hours. What will start out as an elevated
severe hail threat will transition into a damaging wind and
tornado threat during the afternoon as organized rotating updrafts
become more prominent. Convection will spread eastward across the
ArkLaTex through the evening and overnight hours. Conditions to
improve during the overnight hours as storm system exits the
region to the east. /05/
LONG TERM.../Sunday through Thursday Night/
The forecast period begins with model agreement that the closed
upper low will be across the Missouri Valley, lifting into the Upper
Great Lakes during the day on Sunday. The axis with the longwave
trough of this feature will shift east of the area on Sunday, with
the heaviest rainfall shifting east of the area into the Mississippi
Valley early in the day. A few showers will be possible closest to
the low in extreme northern Louisiana and southwestern Arkansas
early on Sunday before the upper low pulls further away from the
area.
Sunday night through Tuesday, weak mid-level ridging aloft along
with a surface high pressure system will slowly move across the
area, allowing for a dry forecast across the area. By Tuesday night,
the area will shift into more of a southwesterly flow aloft with a
warm front lifting into the region. This will allow for the return
of showers and thunderstorms Tuesday night.
Wednesday looks to be the next active weather day after our Saturday
event, however there still is some model inconsistencies with the
timing and strength of the system. It is possible that this feature
will return severe weather to the area as the next upper trough
moves across the southern Plains on Wednesday and into the ArkLaTex
by Wednesday night. Ahead of the feature, strong instability and
moderate shear in the warm sector will bring the potential threat of
tornadoes, large hail, and damaging winds to the area. The chance of
showers and thunderstorms will linger until early Thursday when a
cold front crosses the region.
For temperatures, in the wake of the front, highs on Sunday will be
about 10 degrees below normal in the 60s across much of the area.
With more abundant sunshine Monday into Tuesday, highs will be
closer to normal values in the mid to upper 70s across much of the
area. As a warm front lifts into the area, temperatures will warm
into the upper 70s to lower 80s across the area Wednesday. Behind
that system, highs will be near 70 across much of the area on
Thursday.
04-Woodrum
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 59 74 49 64 / 70 100 60 10
MLU 59 76 55 64 / 50 100 80 20
DEQ 52 62 43 63 / 70 100 80 20
TXK 55 65 47 62 / 70 100 70 20
ELD 57 71 50 61 / 60 100 80 20
TYR 59 72 45 65 / 70 100 40 10
GGG 58 74 46 64 / 70 100 50 10
LFK 63 79 48 68 / 70 100 20 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
13/99