Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/21/18
Area Forecast Discussion
National Weather Service Binghamton NY
926 PM EDT Wed Jun 20 2018
.SYNOPSIS...
A cold frontal boundary will push south through the region
tonight, with high pressure building in behind the front. While
some scattered showers may linger into the evening conditions
will turn sunny Friday. A warm front will lift north through
the region late Friday and Saturday with another chance of
showers.
&&
.NEAR TERM /THROUGH THURSDAY/...
925 pm update...
Very light rain showers out there this evening, mainly from the
NY/PA border south. Mid level s/w and sfc inverted trough
passing ewd across the region...but with most of the instability
well to the south across srn PA along with the majority of the
showers and storms. Have cut back on the nrn extent of the
precipitation in the forecast, and lowered probabilities and qpf
amts as well. Still have mention of valley fog in the forecast,
but confidence is lower than previously thought with a decent
amt of dry air moving in and winds/mixing increasing during
the morning hours. Cannot completely rule it out though...so
left mention in the lowest/most favorable areas for valley fog.
The rest of the forecast looks on track with quiet weather
tomorrow, more sun and warmer temperatures.
Previous Discussion...
Several waves of low pressure will ride along a frontal boundary
to our south. Clouds have overrun the boundary this afternoon.
However, moisture is very limited as evidence with the latest
soundings from the HRRR and RAP. As a result, while the radar
shows quite a few returns mainly scattered sprinkles are falling
in northern PA into the southern tier of NY. Modeling does
indicate another round of showers coming through the Poconos
early this evening with a moister environment in place by then.
A secondary cold front will then pass through the region
overnight resulting in clearing from north to south. Lows
tonight should be in the low 50`s north to around 60 in the
Poconos. Some patchy fog may form as well just before sunrise
but is conditional on the evening clearing and winds going calm
which are both somewhat uncertain.
High pressure will build into the region Thursday resulting in a
mostly sunny day and temperatures quickly rebounding into the
70`s and even 80 in a few spots. MOS guidance as a whole looked
a degree or two too cool based on boundary layer temperatures.
Winds should increase a touch but stay under 10 mph from the
north.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
With the high pressure overhead Thursday night looks rather
cool and undercut temperatures slightly from MOS in the upper
40`s to low 50`s. Daytime highs should rebound with one more
sunny day as the high departs our region into the 70`s and low
80`s. Similar to Thursday where MOS may be a hair cool with
highs. While high clouds should increase on Friday, any
precipitation from an approaching warm front should hold off
till the night due to the drier airmass in place. Winds will
also become southerly on the backside of the high.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
130 pm update... On the large-scale, a short-wave impulse is
still progged to open up, as it heads from the OH Valley across
NY/PA on Saturday. Sunday into Sunday evening, another short-
wave in the northern stream is expected to drop southeastward
from Ontario across the forecast area, ultimately helping to
push a secondary surface cold front/trough off the east coast.
The passage of these features will keep a fairly high
probability of showers over the area this weekend.
From this early vantage point, it appears that shower activity
will be the most persistent on Saturday, and more
scattered/intermittent in nature for much of the region Sunday.
Saturday continues to look fairly stable, so no thunder will be
mentioned for the first half of the weekend. Marginal
instability is progged on Sunday, so will include a small chance
of thunder.
For a good portion of next week, height rises aloft are progged
over the eastern CONUS, with a surface high gradually building
from eastern Canada, across the northeastern U.S., and
eventually off the mid-Atlantic coast. This should lead to
mostly rain-free weather for the first part of next week, along
with temperatures gradually warming day to day.
Highs mostly in the 70s Saturday-Monday, should warm into the
upper 70s-mid 80s range towards the middle of the week.
&&
.AVIATION /01Z THURSDAY THROUGH MONDAY/...
720 pm update...
Mainly VFR throughout the TAF period which is tonight and
Friday. Showers turning to sprinkles and exiting to the
southeast. A few sprinkles for AVP up to 06z but not expecting
any restrictions. Skies are slowly clearing from north to south.
Medium confidence on MVFR vsbys between 09 and 12z at KELM with
valley fog. Skies clear out late tonight there. Winds will be
calm there.
Friday mainly high scattered clouds at all sites.
Tonight light and variable winds at 5 kts or less. Friday
northwest to north winds at 8 kts.
Outlook...
Friday night...VFR.
Saturday through Sunday night...Showers and restrictive
conditions are possible.
Monday...VFR.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...None.
NY...None.
&&
$$
SYNOPSIS...MWG
NEAR TERM...BJT/MWG
SHORT TERM...MWG
LONG TERM...MLJ
AVIATION...TAC
Area Forecast Discussion
National Weather Service Denver/Boulder CO
842 PM MDT Wed Jun 20 2018
.UPDATE...
Issued at 842 PM MDT Wed Jun 20 2018
Radar picking up a few weak showers over Park and Lincoln
counties. Last few visible satellite images showed a little
vertical growth to the clouds over Lincoln county. Not enough
instability for thunder though. Will go with low pops, less than
20 percent, through midnight. The RAP and HRRR are also indicating
isolated showers are possible here. Only other change will be to
tweak cloud cover a little higher for the increase in clouds.
&&
.SHORT TERM...(This evening through Thursday)
Issued at 423 PM MDT Wed Jun 20 2018
Dry air will be over Colorado through Thursday, with a bit drier
air aloft mixing to the surface in the afternoon. This should keep
convection to a minimum, though we should at least get some cloud
cover again and perhaps a few weak showers/storms.
.LONG TERM...(Thursday night through Wednesday)
Issued at 423 PM MDT Wed Jun 20 2018
Models have trended a bit faster with the cold front on Friday,
bringing richer moisture back into the plains but not a lot of
cooling. This will increase the chance of thunderstorms, with some
severe potential if the moisture/heat balance winds up being
right. Since it`s usually tricky to get this to work out, the
marginal risk on the eastern plains in the SPC outlook looks good
at this time. Further west it will still be warm and dry, with a
bit more wind.
Saturday looks to be a recovery day behind the cold front, with
temperatures getting nearly as warm as Friday by the end of the
day. Given the initial stability, low PoPs are in order, but there
is potential for more in it warms up enough as the plains should
still have good moisture.
Fair consistency on an upper low moving over the Rockies at about
our latitude Sunday and Monday. Much will hinge on the exact path,
as there will likely be decent precipitation on the north side of
this system. Our blended forecast guidance has a gradient in
moisture across our area, with a better chance of significant rain
over the northern border and eastern parts of our area. Whether or
not there is substantial rain or severe weather will depend on how
much the low levels cool and the timing of the lift. Right now the
cooler solutions are showing highs around 70 on Sunday, while the
warmer/drier ones only drop to around 80. Somewhere in between
with the moisture might be a sweet spot for thunderstorms. For now
the blended solution of cooler with a pretty good chance for rain
at some point across most of the area will do.
Ridging behind the trough will lead to a warm/dry southwest flow
aloft by midweek. It could be back to summer temperatures, though
soil moisture may take the edge off of the heat if we get another
round of rain before then.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 842 PM MDT Wed Jun 20 2018
VFR through Thursday. Northeast winds will slowly turn east and
end up a southerly direction after 06Z. A period of west winds is
possible at KDEN Thursday morning, but speeds will be under 10
knots. Little or no thunderstorm activity Thursday afternoon.
&&
.FIRE WEATHER...
Issued at 423 PM MDT Wed Jun 20 2018
Conditions may approach Red Flag criteria in South Park on Friday
afternoon. It should be dry enough, but the wind speeds are
uncertain. Across the rest of the mountains it will be warm and
dry Thursday and Friday with some afternoon breezes, but not as
much as in South Park.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Meier
SHORT TERM...Gimmestad
LONG TERM...Gimmestad
AVIATION...Meier
FIRE WEATHER...Gimmestad
Area Forecast Discussion
National Weather Service Boston/Norton MA
1105 PM EDT Wed Jun 20 2018
.SYNOPSIS...
Showers are likely overnight S of the MA/CT/RI border as a low
pressure center sweeps W to E just S of New England. Bit cooler
with a spot showers Thursday. Seasonable Friday while turning
unsettled Saturday, continuing through early Monday with the
chance of showers and thunderstorms. Dry weather thereafter
through Thursday, with a renewed chance of wet- weather Friday
into the following weekend.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
1030 PM Update...
AS low pressure approaches the NJ coast this evening, noting
very spotty shower activity across S coastal CT and Long Island
on latest KBOX and NE regional 88D radar imagery. Only ground
truth seen at 02Z was across central Long Island, where both
KISP and KHWV were reporting -RA. Pretty dry airmass in place
away from the S coast, with T/Td spreads from 10 to 16 degrees.
00Z NAM and RAP BUFKIT soundings also showing a dry airmass
through the layer, especially on the RAP model data.
Clouds AOB 5000 ft were reported across a few spots on Long
Island, while mid and high clouds were the rule further N.
Noting clearing line moving slowly but steadily S on latest
GOES-East RGB Microphysics composite and IR satellite imagery.
With these drier trends, have pushed the northern edge of the
precip further S, but did keep mention of mainly CHC POPs
across central CT/central RI and S coastal Mass. Have LKLY POPs
confined to the immediate S coast and islands after midnight.
With a mainly stable airmass, as well as no lightning being
reported anywhere across the NE U.S., have removed mention of
thunder from this update.
Have updated near term to bring conditions current and
incorporated current thinking into the overnight forecast.
Previous Discussion...
Rain moving in just around midnight, exiting the early morning
hours on Thursday. Latest radar returns just a pre-cursor, acting
to moisten the environment, however low-levels still considerably
dry as surface high pressure retreats off to the E.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Thursday into Thursday Night...
Precipitation along the south coast will be ongoing early in the
morning as surface low pressure continue to move across the southern
waters. Approaching wave from the northeast will drive this low
south and offshore leading to an end of the precip. Will have to
watch for a spot shower or two during the day across the interior.
Increasing low level moisture combined with steep lapse rates and
upper level trigger could lead to a few showers especially along the
higher terrain. Thus have insert a slight chc for a shower during
the afternoon.
Temperatures on Thursday will be warmer across the CT valley, but
quite cool along the east coast. Winds will switch from the
southwest to the northeast a front passes through. This will bring
the cooler maritime airmass onshore. Could see over a 10 degree
difference across the region.
Temperatures overnight will cool off, but not as much as prev
through. Increasing low level moisture trapped within the inversion
will result in stratus and fog across the area. Still trying to
narrow down best location, but something to watch for in the coming
shifts.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
*/ Highlights...
- Saturday perhaps not a washout, skirting rains S/E
- Showers / t`storms N/W Sunday, sweeping SE into Monday morning
- Prolonged dry conditions during the week
- Watching weeks-end for additional wet-weather disturbances
*/ Overview...
Summer is coming. Prevailing N Pacific H5 trof downstream of which a
split flow regime emerges over western N America. S tug by cascading
systems into a Baffin Bay gyre, H85 temperature warm anomalies build
into the Great Lakes / St. Lawrence River Valley per 5-day averages.
Subsequent higher heights, more dominant N Atlantic high especially
towards Bermuda, invoking a S warm, moist pump from the Gulf. Would
appear seemingly that a general H5 trof pattern remains over the NE
CONUS, however weaker under an increasing weight of high pressure,
subsidence. Weak frontal boundary passages with uncertain outcomes,
where precipitation looks prominent upstream only to wash out upon
arrival. Confident warming trend into July, while a nod of concern
of drier than average precip, perhaps enhancing ongoing abnormally
dry conditions. Some unknowns, a NE Atlantic rex-block evolving into
W Europe, and tropical activity off Africa into the Caribbean. Will
hit on any targets of opportunity below.
*/ Discussion...
Saturday...
Lean away from heavy rain with wedging high pressure, drier air, as
the sub-tropical, +2" precipitable water airmass resides S, perhaps
skirting SE New England. Have seen this before with winter systems
in where isallobaric flow dams up against an approaching OH River
Valley low. Can`t rule out scattered shower, thunderstorm activity
towards days end, but leaning with 20.12z GFS/NAM in SE skirting
outcomes fueled by low-level convergent inflow towards a held-up
warm frontal boundary. De-amplifying mid-level trof, weak frontal
boundary parent, pushes the sub-tropical axis offshore ahead of an
oncoming sharper H5 trof axis for Sunday into Monday. Not ready to
call the day a washout.
Sunday into Monday...
Afternoon showers and thunderstorms into evening, however mainly N/W
interior locales. Possibly strong but not thinking severe per shear
and 0-6 km mean wind accompanying along with marginal instability.
Better sub-tropical, unstable and muggy airmass S/E, offshore, yet
enough moisture that with destabilization should allow activity to
pop within cyclonic regime out ahead of overnight sharp cold front,
pushing offshore around Monday morning. Accompanying vortmax, strong
deep layer ascent, may have to watch SE New England into Monday up
against a more muggy airmass lingering offshore as to potential out-
comes. Thinking a majority of activity is nuisance.
Overall, for the 3-day period Saturday through Monday, could be a
situation of interior N/W destabilization with S-shoreline skirting
soakers. High pressure wedge from the E, locations up the ME coast
down into northeast MA may end up being the precipitation losers.
End of the week...
Series of frontal boundaries, slowing, stalling against the building
wall of Atlantic high pressure. Have to watch closely strength of
synoptic features round the convergence boundary, whether there is
the possibility of prolonged outcomes over any one particular area.
Noteworthy is a sudden tick upward of precipitation within ensemble
members.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Thursday Night/... High confidence.
Overnight...
Mainly VFR. May see local MVFR at times along the immediate S
coast, Cape Cod and the islands in any -SHRA and patchy fog. Low
risk of brief IFR conditions across the islands mainly in CIGS
after 06Z or so. SW winds up to about 10 kt shifting to light NW
after 08Z or so.
Thursday...
VFR. Lingering S-coastal / Island -SHRA with MVFR CIGs, a brief
threat of IFR CIGs for ACK around 12-18z. Improvement during the
afternoon hours, CIGs lifting 4-7 kft agl, as spot -SHRA develops
across interior S New England around ORH. N winds turning NE.
Thursday night...
VFR to start but with northeast flow believe low levels will
saturate dropping cigs and vsbys to MVFR conditions.
KBOS Terminal...
Keep -SHRA S of the terminal overnight. VFR prevailing.
KBDL Terminal...
Expect -SHRA to be immediately S of the terminal. Will go low
end VFR overnight however there is a risk of some MVFR possibly
sneaking in prior to morning.
Outlook /Friday through Monday/...Moderate confidence.
Friday: VFR.
Friday Night: VFR. Breezy. Slight chance SHRA.
Saturday through Saturday Night: SHRA likely, chance TSRA.
Sunday through Sunday Night: Breezy. Chance SHRA, slight chance
TSRA.
Monday: Breezy. Chance SHRA.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Thursday Night/...High confidence.
Passing low pressure system across the southern waters will
bring scattered showers which could briefly reduce visibility.
Seas could build to 3 feet. May see brief gusts up to 20 kt
across the southern near shore waters through 06Z tonight.
Otherwise, SW winds will shift to a more NE direction Th
lasting into Thu night. Could see local vsby restrictions in
patchy fog. Conditions remain below SCA.
Outlook /Friday through Monday/...Moderate confidence.
Friday: Winds less than 25 kt. Seas locally approaching 5 ft.
Friday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of rain showers.
Saturday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers, slight chance of thunderstorms.
Saturday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Rain showers likely, chance of thunderstorms.
Sunday: Winds less than 25 kt. Local rough seas. Chance of rain
showers.
Sunday Night: Winds less than 25 kt. Local rough seas. Chance
of rain showers, slight chance of thunderstorms.
Monday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...Dunten
NEAR TERM...Sipprell/EVT
SHORT TERM...Dunten
LONG TERM...Sipprell
AVIATION...Dunten/Sipprell/EVT
MARINE...Dunten/Sipprell/EVT
Area Forecast Discussion...Updated
National Weather Service Billings MT
919 PM MDT Wed Jun 20 2018
.UPDATE...
Main updates to the forecast to reduce evening pops east and to
add mention of fog overnight into tomorrow morning central and
east. Diurnal convection fading over southeast Montana as the sun
sets. Had reports of near 4 inch per hour rainfall rates from
storms this afternoon. Another disturbance will work into the area
from the west late tonight. CAM models showing scattered
convection from this feature spreading as far east as Billings by
sunrise. Already had isolated to scattered showers/tstms in the
forecast for western zones, and spread them a bit further east to
cover the latest model solutions. With all the heavy precipitation
over the past few days, clear skies for at least a portion of the
night and light winds up to 5kft AGL or higher, would expect to
see at least fog in the river valleys overnight, but could be a
bit more widespread. HRRR showing this potential in the cloud
fields so added patchy mention to the forecast through 10 AM
tomorrow morning. Chambers
&&
.SHORT TERM...valid for Thu and Fri...
Scattered showers and thunderstorms will generally come to end
overnight night as the low pressure system moves out and some
shortwave ridging builds in. This break will be short lived
however as the ridging gives way to the next shortwave trough. As
the wave comes into the area, shear values still look to increase
along with the instability. The high-res CAMs are showing some
convection could be on the strong side. There continues to be a a
marginal risk for some severe thunderstorms, given the shear and
instability. The bigger hazard will be heavy rainfall, as the PWs
will remain high. Moving into tomorrow night the instability and
shear will decrease, so moving east of Billings the threat of
strong thunderstorms will be decrease. Reimer
On Friday, an upper level shortwave trough will be moving
east/southeastward across the Northern Rockies. This trough should
bring a good chance of showers and general thunderstorms to the
area. The highest chance of rain should be over SE MT where a
low-level trough/convergence zone should be...but showers and
t-storms are also possible over the rest of the area as
sufficient instability should be in place with disturbances
moving through the flow. Shear looks weak so am not expecting
severe weather. Precipitable water values should remain a bit
above normal, so the showers and t-storms can drop additional
heavy rainfall. RMS
.LONG TERM...valid for Sat...Sun...Mon...Tue...Wed...
On Friday, an upper level shortwave trough will be moving
east/southeastward across the Northern Rockies. This trough should
bring a good chance of showers and general thunderstorms to the
area. The highest chance of rain should be over SE MT where a
low-level trough/convergence zone should be...but showers and
t-storms are also possible over the rest of the area as
sufficient instability should be in place with disturbances
moving through the flow. Shear looks weak so am not expecting
severe weather. Precipitable water values should remain a bit
above normal, so the showers and t-storms can drop additional
heavy rainfall.
The unsettled weather pattern looks to continue through Sunday as
troughing connected to an upper low over southern WY remains over
the region continuing shower and thunderstorm chances.
For Monday through Wednesday, models largely show a drier pattern
with a few caveats. On Monday, ECMWF brings an upper low closer
to SE MT and thus a chance of showers/t-storms there, while the
GFS keeps the low more to the south and thus gives dry weather
over SE MT. Given this model uncertainty, have a small chance of
showers/t-storms over SE MT. The next chance of showers/t-storms
for much of the area looks to be Tuesday night with models
bringing a fast-moving shortwave trough and surface cold front
across the region.
High temperatures will be in the 70s Friday through Sunday, 80s
for Monday and Tuesday, then 70s for Wednesday. STP/RMS
&&
.AVIATION...
Isolated showers and thunderstorms will continue to diminish
through midnight over SE Montana. A disturbance will bring
isolated to scattered showers and thunderstorms to western
mountains and foothills around midnight, spreading east to around
the Billings area around 12z. Local MVFR or lower conditions can
be expected with moderate rainfall near showers and thunderstorms.
Expect periods of mountain obscuration overnight into tomorrow
morning. Patchy fog is possible overnight through mid morning
mainly confined to river valleys east of Billings. Chambers
&&
.PRELIMINARY POINT TEMP/POPS...
Thu Fri Sat Sun Mon Tue Wed
-----------------------------------------------------------
BIL 055/081 056/074 056/073 054/075 056/084 059/084 056/077
13/T 66/T 54/T 53/T 10/U 00/U 21/U
LVM 051/076 051/071 048/069 047/073 048/084 052/084 049/075
27/T 86/T 45/T 43/T 10/U 00/U 10/U
HDN 054/083 056/074 055/076 053/076 055/085 058/087 055/079
02/T 46/T 54/T 64/T 20/U 00/U 10/U
MLS 056/081 059/076 058/077 058/078 059/083 059/087 058/079
21/U 55/T 54/W 44/T 21/B 00/U 11/U
4BQ 052/080 058/076 058/076 055/076 057/081 057/087 057/080
11/U 56/T 54/T 55/T 32/W 00/U 10/U
BHK 054/078 056/076 055/075 054/077 056/080 056/085 057/079
20/B 36/T 56/T 44/T 31/B 10/U 11/U
SHR 050/079 053/072 052/073 051/070 051/079 054/084 054/078
22/T 46/T 65/T 66/T 31/B 00/U 10/U
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
604 PM MDT Wed Jun 20 2018
.SHORT TERM...(This evening through Friday night)
Issued at 230 PM MDT Wed Jun 20 2018
Upper level features this afternoon were a trough over the Northern
Plains and ridge over the Desert Southwest. Wrap-around mid-level
moisture and weak instability were producing widely scattered
showers and isolated tstorms from eastern WY into western SD and
northwest NE. This activity will progress south and east into
portions of southeast WY and western NE Panhandle through late
afternoon then dissipate.
12Z short range models/ensembles concur that the southwest CONUS
ridge will build north and east across the Rockies and high plains
through Thursday. The only fly in the ointment will be a weak
disturbance aloft and front tracking east across northern WY
Thursday afternoon. Convection with this system will be isolated
and will mainly occur Thursday evening over much of southeast WY.
The NAM progs a ribbon of instability /1000-2000 j/kg SBCAPE/
along and just east of the Laramie Range between 21Z and 03Z.
Cannot rule out a few stronger storms with small hail and strong
gusty winds due to rather high LCLs. High temperatures Thursday
will be 10 to 15 degrees warmer than today.
Friday is looking more convectively active as a stronger upper
level disturbance and front track east across MT and northern/eastern
WY during the afternoon and evening. Instability will peak around
21Z with SBCAPEs progged as high as 2500-3000 j/kg per the NAM
across much of the western NE Panhandle into far southeast WY. The
SPC Day 3 outlook has a Marginal Risk for severe tstorms for this
general area with the main threats large hail and strong gusty
winds. Convection may persist into the nighttime hours east of
I-25. Highs Friday will trend slight cooler west of the Laramie
Range, with 70s to lower 80s east.
.LONG TERM...(Saturday through Wednesday)
Issued at 230 PM MDT Wed Jun 20 2018
Main focus this period will be with the upper low that will be moving
across the area primarily Sunday through Monday. Saturday should be
mainly dry with a short upper ridge passing across the CWA. Showers
and a few storms should increase Saturday night as the upper low
approaches from the northwest, with surface upslope flow beneath some
diffluent flow aloft. Sunday into Monday should see widespread showers
and a few storms as the upper low treks across Wyoming. Not much
instability progged on Saturday, then about 500-1000 J/kg near the
Colorado border Sunday, so a few stronger storms possible. Some decent
rainfall amounts expected before the activity winds down late Monday,
with the low progressing east across Nebraska. Tuesday and Weds looking
warm and mainly dry though as bit of afternoon convection possible
mainly near the mtns late Weds.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 551 PM MDT Wed Jun 20 2018
Isolated -SHRA is shifting from NW to SE across Converse into
Platte County and into portions of Sioux County, Nebraska as of
00Z. The -SHRA will dissipate over the next hour and not likely
impact any TAF sites. North winds of 10 to 20 knots are occurring
as of 00Z this evening and will drop to 5-12kt overnight while
remaining for the north. Tricky portion of the forecast will be in
the early dawn hours from 11-14Z as patchy areas of fog will be
possible across the High Plains of Nebraska and into portions SE
Wyoming towards CYS. The question will be overall spatial coverage
of the fog and if it develops close enough to a TAF site. HRRR/NAM
output suggest low enough dewpoint depressions for ground fog to
form given the saturated grounds. GFS is less bullish while the
RAP has 1-2F dewpoint depressions. The second caveat will be how
low can the winds become during this time frame. If winds drop
below 5 knots, greater fog coverage and density could occur near
Nebraska TAF sites and possibility into CYS. Have trended towards
patchy MVFR ground fog visibilities this TAF cycle and will
monitor for updates on the 06Z issuance. What fog does that form
will dissipate through 14-15Z Thursday morning. Scattered TSRA is
expected to develop over the higher terrain of WY after 21Z and
will shift east into the central and southern Nebraska Panhandle
near to after 00Z tomorrow evening.
&&
.FIRE WEATHER...
Issued at 230 PM MDT Wed Jun 20 2018
Minimal fire weather concerns late this week through early next week.
Lowest relative humidities (20 to 25 percent) will exist over much of
Carbon County during this period. After the recent wet pattern, today
and Thursday will be drier. The trend toward cooler and wetter weather
returns this weekend and lasts into early next week. Warmer and drier
conditions will return Tuesday and Wednesday.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
SHORT TERM...MAJ
LONG TERM...RE
AVIATION...JSA
FIRE WEATHER...MAJ
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
842 PM CDT Wed Jun 20 2018
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
While widespread showers continue in the far northwestern portions
of the area in proximity to better lift, the loss of heating to
the south has allowed convection to wane considerably. The HRRR
remains consistent in its forecast with the consolidation of the
precip areas to the west into a somewhat more organized band that
will move into the Delta region after midnight. The slow eastward
movement combined with PWs around 2.25 inches will support a
heavy rainfall/localized flooding threat late tonight into early
Thursday morning in this area. Made a few adjustments to the
forecast based on latest model and observational trends./26/
Prior discussion below:
Tonight and tomorrow:
Convection is having an easier time getting going this afternoon,
largely due to the initial influence of an anomalously strong (for
"summer") upper disturbance dropping toward the Mid to Lower MS
Valley. Also helping is the very soupy air mass over the region
containing high precipitable water values ranging from 1.8 to 2.2
inches. Most of the heavy downpours are moving this afternoon,
limiting the flood threat. However, later tonight model consensus
is high that focused moisture advection and increasing lift
running north into the Arklamiss Delta should fuel widespread
heavy downpours and thunderstorms which will have a tendency to
train over the same ground. Despite wind shear increasing, at this
point instability looks to remain low enough to preclude much of
a severe weather threat through tonight. We updated our HWO and
graphics to include a LIMITED flooding threat in the mentioned
Delta areas through the course of the night. Away from the Delta,
late afternoon and early evening shower and thunderstorm activity
should be diminishing before midnight, at least in most cases.
Tomorrow, the axis of widespread showers and thunderstorms should
be shifting east/southeast out of the Arklamiss Delta through the
morning hours as the associated low level trough presses forward
ahead of the advancing disturbance aloft. The risk for flooding
with the activity along and north of the Natchez Trace corridor
should not be zero, but we will hold off mentioning any flooding
concerns in the HWO/graphics for Thursday at this juncture,
primarily because there should be less potential for prolonged
training of heavy rainfall. By afternoon we anticipate the glob of
clouds and widespread showers and thunderstorms may start breaking
up over the heart of the region, allowing some better
destabilization region-wide before dark. Working CAPE values
perhaps sneaking over 2000 j/kg in the afternoon time frame could
work with deep layer shear approaching 30 kts to bring at least a
MARGINAL severe weather threat, mainly along and north of I-20.
The main risk with any severe storms in the afternoon should be
damaging wind gusts. Highs across the region will mostly be
limited to the upper 80s with all the clouds and rain. /BB/
Thursday night through Tuesday:
An upper cutoff low over Missouri/Illinois will move incrementally
eastward through the Midwest on Friday and then become absorbed into
the main upper trough on Saturday while over the Great Lakes region.
The cutoff low will drop a frontal boundary south into northern
Mississippi on Friday. Ahead of the front lies the moisture rich
summertime regime which will foster the formation of scattered
showers and storms in north MS on Friday. Looking at the severe
parameters, 2500j/kg MU CAPE values along with 40kt bulk shear
values could be enough to form a cluster of strong to severe storms
and, should the storms move in the southeasterly direction of the
bulk shear vectors, perhaps an organized/bowing line of storms. It
is a little too far out for the CAMs to grab onto this idea but
there are some indications that this is one possibility. For now,
the marginal risk in the HWO seems appropriate but may need to be
increased in the coming time. The main risk at this time seems to be
damaging wind gusts with a secondary threat of hail. Another
consideration will be the heat. With abundant moisture and highs in
the low 90s, heat indices over much of the area will be above 100
and approaching 105 at times on Friday.
Going into the weekend, diurnal activity will be less on Saturday as
the stalled boundary dissipates and upper northerly flow becomes
more westerly and then southerly on Sunday. Convection will be
limited this weekend and then increase a bit on Monday as high
pressure settles over the area again. Temps will increase into the
low to mid 90s with heat indices near to just above 100. /10/
&&
.AVIATION...
00Z TAF discussion:
Numerous showers and a few thunderstorms look to continue between
GLH, GWO and to a lesser extent GTR through much of the upcoming
period. Further south, convection will be more scattered during
the evening diminishing by late evening with MVFR ceilings
developing after midnight. Convection will begin increasing again
from the west prior to dawn and linger through much of the daytime
Thursday. Where the heavier showers/storms occur, ceilings and
visibilities will be briefly lowered./26/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 73 87 72 91 / 33 69 18 32
Meridian 73 88 72 91 / 19 60 22 35
Vicksburg 73 88 73 91 / 66 78 14 35
Hattiesburg 74 89 71 92 / 8 53 21 17
Natchez 73 87 73 91 / 38 69 8 12
Greenville 73 88 72 90 / 79 65 29 53
Greenwood 73 86 71 89 / 74 78 37 55
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...None.
LA...None.
AR...None.
&&
$$
Area Forecast Discussion
National Weather Service Lake Charles LA
1006 PM CDT Wed Jun 20 2018
.UPDATE...
Per coordination with the Weather Prediction Center, remnant MCV
over SE TX will enhance precipitation potential in a already
saturated and unstable airmass with PW`s over 2". Have increased
areal rainfall amounts around 1 to 2 inches with the possibility
of 3 to 5 inches in isolated locations across the Flood Watch
areas of Southeast Texas including Jefferson, Orange, Southern
Jasper & Newton counties. Updated forecast and Flood Watch has
been sent.
DML
&&
.PREV DISCUSSION... /issued 828 PM CDT Wed Jun 20 2018/
DISCUSSION...
Wx map shows weak high pressure over the SE U.S. this evening,
keeping a moist southeast flow off the Gulf. Not much sfc
reflection of the large trough over coastal TX and N Mexico.
However, weak cyclonic rotation continues roughly between 925mb-500mb
across S TX that`s keeping excellent lift, coupled with PW`s over
2" (2.13" at 00Z LCH sounding), to provide copious amounts of
rainfall where the training convective band sets up. One such band
is continuing to slowly move east across SE TX, mainly northwest
of Beaumont/Orange at this hour. This will continue to feed off of
the moist and unstable air over our region this evening and
overnight. Latest HRRR guidance shows this will likely move
further east into Western Louisiana and unfortunately, over the
remainder of Southeast Texas this evening and overnight. At this
time, looks like rainfall totals of 1" to possibly 2" band could
stay northwest of Beaumont/Orange area, but even the additional
rainfall of 0.5 to possibly 1.0" expected this evening and
overnight could result in drainage problems as the ground remains
absolutely saturated. Flood watch will continue for the hardest
hit counties of Jefferson, Orange, and Southern Jasper & Newton
through 7 AM.
DML
PREV DISCUSSION... /issued 613 PM CDT Wed Jun 20 2018/
AVIATION...Showers and storms can be expected in the area through
the period, however coverage will be higher near KBPT. Lower
ceilings can also be expected overnight and lower vis may occur in
precip. Winds will be south to sw at or less than 10 kts.
PREV DISCUSSION... /issued 441 PM CDT Wed Jun 20 2018/
DISCUSSION...
Short Term...Tonight and Thursday...
Regional radar shows scattered showers and thunderstorms this
afternoon, mainly across Southeast TX and Central LA. Much of this
activity should continue through the afternoon and into this
evening. Latest HiRes guidance continues to push a band of heavier
rain eastward into Southeast Texas late tonight, though there is
still some uncertainty as to when this will move into our area and
what rainfall totals we can expect. Eventually, these showers
should spread into southwest Louisiana and across the area during
the day on Thursday.
After the last several days of heavy rain across southeast Texas,
RFC flash flooding thresholds are still rather low at 2"-3" over
three hours and 3"-4" over six hours. While "official" forecast
totals through tonight are expected to be around or less than one
inch, 12Z HREF guidance indicates the potential for more robust
convection to produce rainfall amounts that will approach flash
flood guidance. Additionally, guidance has preformed poorly over
the past several days with regards to the placement of convective
bands and rainfall amounts. The axis of steadier precipitation is
expected to shift northeast from central Texas during the
overnight hours and any additional heavy rain received overnight
across Southeast Texas has the potential to produce local flash of
preci flooding. Therefore, it was decided to lean on the side of
caution and extend the Flash Flood Watch through Thursday morning
for southeast Texas. Further east across western Calcasieu and
Cameron Parishes, flash flood guidance is running higher and the
likelihood of precipitation exceeding said guidance is lower
resulting in the Watch being cancelled.
RACKLEY
Long Term...Friday through Tuesday...
The upper level low contributing to the heavy rainfall over the
past several days is expected to become integrated with a upper
level trough Thursday with the trough axis shifting east of the
region during the day Friday. The combination of the exiting
trough, the upper level high over the western Atlantic expanding
into the eastern Gulf, and height rises in advance of a digging
shortwave trough from the Pacific northwest will result in weak
ridging across the MS Valley through the weekend into early next
week. This will contribute to decreasing deep layer moisture with
forecast PWAT values of less than 1.5" Friday through Sunday. This
will result in drier conditions and warmer conditions through
Sunday.
Early next week, the digging Pacific shortwave and upper level
ridge will result in a more favorable pattern for return flow and
deep layer moisture will begin to rebound to climatological values
for late June. This will result in a return of the typical diurnal
convection beginning on Monday and continuing through the middle
of the week.
26
MARINE...
Winds and seas will gradually decrease through the evening and
Thursday as the northwest Gulf pressure gradient continues to
relax. Scattered showers and a few thunderstorms will continue
tomorrow before coming to an end Friday.
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 75 87 74 94 / 80 60 10 20
LCH 77 85 77 91 / 80 50 10 20
LFT 77 85 76 92 / 20 40 10 20
BPT 77 86 76 91 / 80 50 10 20
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...Flash Flood Watch until 7 AM CDT Thursday for TXZ215-216-261-262.
GM...None.
&&
$$
PUBLIC...04
Area Forecast Discussion
National Weather Service Memphis TN
853 PM CDT Wed Jun 20 2018
.DISCUSSION...
Numerous showers and scattered thunderstorms continue to develop
across the Lower Mississippi Valley this evening. A lead mid
level shortwave moving through the region, in advance of an upper
level low dropping southeast from the Plains, is driving this
development. Instability continues to wane so severe weather
chances are small though a strong thunderstorm with gusty winds
could occur overnight. Given the coverage upstream and the latest
HRRR runs decided to go with categorical pops along a corridor for
Clarksdale to Memphis to Paris after midnight. Most of the rain
will move east of the area Thursday morning with redevelopment
expected along the cold front during the afternoon.
SJM
&&
PREV DISCUSSION... /issued 313 PM CDT Wed Jun 20 2018/
At 3 PM around the Mid-South, temperatures were generally in the
low to mid 80s. Showers were ongoing, with a few isolated
thunderstorms becoming apparent on radar. An increase in the
coverage of showers and storms is expected as the evening
progresses.
The latest H5 analysis depicts an upper ridge to the SE of the
Mid-South, with an amplifying trough just to the NW. With the
region wedged between these features, southwesterly flow is
present aloft. A few weak embedded impulses in this flow have led
to cloud cover and precipitation today. This will continue
tonight, enhanced by a frontal boundary moving ESE into the
region. This will make showers and thunderstorms likely during the
overnight hours. Enough instability could exist to aid one or two
of the storms in becoming strong this evening and tonight, with
gusty winds and heavy rainfall the primary threat.
The greatest rain chances will be in the eastern half of the FA on
Thursday as the front progresses. Meanwhile, the upper closed low
moves over the region, which will keep sky cover and precipitation
chances in the forecast each day through the weekend. The surface
boundary stalls out over northern Mississippi, keeping the best
chances for showers and thunderstorms focused there for Friday
and Saturday. Temperatures will remain the 80s each afternoon, a
few degrees cooler than average for late June, as the upper low
transits the region through the weekend.
By late Saturday the upper trough kicks east, with more zonal flow
moving in aloft over the region. This will keep conditions
unsettled, as several weak impulses embedded in this flow will
keep shower and thunderstorm chances present into early next week.
The best chance during this period looks to be on Sunday as a
surface low moves just to the NW of the region. An upper ridge
begins to build back into the region by the middle of next week,
which will reduce rain chances and allow temperatures to warm back
into the 90s late in the period.
ZDM
&&
.AVIATION...
/00z TAFs/
Scattered showers, with isolated thunderstorms, will continue this
evening but are expected to increase in coverage overnight as a
shortwave trough moves across the region. Tempo groups were
retained at most terminals late tonight for TSRA and tempo IFR to
low end MVFR ceilings/visibility within convection. Low clouds are
expected to hang around Thursday morning with generally benign
weather anticipated roughly 15-21z tomorrow. Storms are expected
to redevelop after 20z.
Johnson
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion...CORRECTED
National Weather Service Paducah KY
620 PM CDT Wed Jun 20 2018
.UPDATE...
Issued at 620 PM CDT Wed Jun 20 2018
Updated aviation discussion for 00Z TAFs.
UPDATE... Issued at 615 PM CDT Wed Jun 20 2018
Updated near term public forecast to account for showers and
isolated thunderstorms currently spreading into southeast Missouri
from northeast Arkansas. Also attempted to better define timing of
peak precipitation chance from west to east across the region
overnight into early Thursday morning. Model forecast soundings
suggest a substantial decrease in instability tonight. Given the
relative lack of lightning with the ongoing activity, decided to
lower thunder chances tonight and early Thursday morning while
raising the overall chance for general shower activity. Remainder of
forecast is unchanged.
.SHORT TERM...(Tonight through Friday night)
Issued at 112 PM CDT Wed Jun 20 2018
PM convection is firing and we are just now getting our first
lightning strikes, in our north. The HRRR has a decent modeling of
the current radar pic, and it picks up on the best focusing
mechanism in the vicinity of the surface boundary around/just to
our north. More advective development is coming in on the moist
tongue, and the HRRR suggests it will pick up after nightfall in
the south, while others may experience a reprieve in overall
activity. As the front sags south overnight, and the moist tongue
continues unabated, thunderstorm coverage increases especially
after midnight and into tmrw. Tmrw pm, we`ll have a marginal risk
of svr, due to heated parcels and increasing shear by about 10 kts
in the lower 6KM as compared to today. Low level lapse rates with
the steepening profile will be sufficient for strong-svr storms,
but must overcome negating lapse rates aloft. The proximity of the
upper Low and assist from the front may be just enough to do this,
for our continued marginal risk svr thru the evening hours tmrw.
Otherwise PW`s in the mid inch range will make locally heavy rains
a hazard as well.
Higher pops translate east with the front Friday, before waning
some Friday night in the post frontal wake airmass. The convective
clouds will tamp down daytime temps after today, while humidity
remains high with 70s plus td`s til after fropa, when we fall back
into the 60s later Friday-Friday night.
.LONG TERM...(Saturday through Wednesday)
Issued at 112 PM CDT Wed Jun 20 2018
The parent Low will be dragging the front away Saturday, on up the
mid-upper Ohio river valley. But another fast moving/fast shaping
system will drop out of the westerlies from the High Plains, and
bring another cold front into/thru the area Saturday night-Sunday.
This will spike pops again on it moves across the mid Mississippi
river valley, as it lays out to our south and goes quasi
stationary. That yields an early week lull, before it is eaten
away at by high pressure ridging throughout the column heading
into the mid week period. Still, with daytime temps in the 80s,
and dew points returning to the 70s, we won`t be able to rule out
at least a diurnally natured shower/storm pop in some part of the
area during the early to mid work week period.
.AVIATION...
Issued at 620 PM CDT Wed Jun 20 2018
Isolated showers and storms early this evening will tend to diminish
with loss of heating. However, a much larger and more organized area
of showers and storms will arrive after midnight in association with
an upper-level disturbance. This rain will likely bring some lower
cigs, including areas of ifr during the early morning hours.
Conditions will improve to vfr during the day Thursday, but some
isolated storms will redevelop in the afternoon. Updated near term
public forecast to account for showers and isolated thunderstorms
currently spreading into southeast Missouri from northeast Arkansas.
Also attempted to better define timing of peak precipitation chance
from west to east across the region overnight into early Thursday
morning. Model forecast soundings suggest a substantial decrease in
instability tonight. Given the relative lack of lightning with the
ongoing activity, decided to lower thunder chances tonight and early
Thursday morning while raising the overall chance for general shower
activity. Remainder of forecast is unchanged.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...None.
MO...None.
IN...None.
KY...None.
&&
$$
UPDATE...RJP
AVIATION...MY
Area Forecast Discussion
National Weather Service Portland OR
815 PM PDT Wed Jun 20 2018
.SYNOPSIS...Increased marine clouds and cooler temperatures Thursday
and Friday will give way to warmer and sunnier weather over the
weekend before cooler and cloudier conditions return early next week.
&&
.SHORT TERM...Tonight through Saturday...Water vapor satellite
imagery reveals a shortwave trough moving northeastward across
southwest Oregon. Plenty of showers and thunderstorms developed in
advance of this feature across the Oregon and Washington Cascades
earlier this afternoon and evening. Speed shear was rather meager
across the area today, which led to updrafts struggling to sustain
themselves. A thunderstorm in the southern Lane County Cascades where
0-6km shear was slightly greater likely contained the largest hail of
the afternoon based on doppler radar signatures. However, we have not
received any ground truth reports verifying whether or not large hail
was observed under any of the thunderstorms in which warnings were
issued this afternoon and early this evening.
Several convective allowing models including members of the HREF and
HRRR suggested thunderstorms were a good possibility for the Portland
metro this evening. Several updrafts (in the form of towering
cumulus) went up around the Portland metro during the time the sea
breeze arrived, but no individual updraft could sustain itself for
reasons not completely known at this point. A few models have
continued to suggest elevated thunderstorms are a possibility
between 8-11pm this evening as the marine layer deepens and is able
to interact with the instability still present above 5000 feet.
Given few signs this will materialize per latest radar and satellite
imagery, it appears the chance of thunderstorms is certainly
diminishing across most of the area. Will maintain a slight chance
of a thunderstorm through the late evening hours to account for the
uncertainty, though.
Otherwise, the marine layer is quickly spreading into the Willamette
Valley with temperatures already in the low to mid 60s in
Kelso/Longview, McMinnville, Salem and Eugene. Expect marine clouds
to push well into the Cascades by daybreak on Thursday with sunshine
returning in the mid to late afternoon hours. Temperatures will be
slow to warm with high temperatures likely only topping out in the
mid 70s. Expect a near repeat Friday before upper level high pressure
shifts over the region on Saturday and results in fewer morning
clouds and afternoon temperatures approaching 80F in the Willamette
Valley. /Neuman
&&
.LONG TERM...Saturday night through Tuesday night...A surface thermal
trough strengthens along the N. CA and S. OR coast Saturday night as
high pressure dominates inland, and offshore flow should keep marine
clouds off the coast Saturday night. A sunny start Sunday will allow
slightly warmer temperatures Sunday afternoon with high temperatures
remaining above the seasonal normals. Models are in excellent
agreement that an upper level trough will send a series of shortwave
troughs over the region Sunday night through Tuesday for increased
morning clouds and cooler afternoon temperatures. ~TJ
&&
.AVIATION...Thunderstorms have developed over the Cascades this
afternoon. As time progresses this afternoon, thunderstorms will
start to develop farther west, impacting TTD and PDX around 00Z
this evening. Could even see a thunderstorm as far south as SLE,
but better chance will be farther north. Thunderstorms should
start to diminish after 02Z-03Z. If a thunderstorm passes over a
terminal, expect a period of heavy rainfall reducing flight
conditions. Small hail and gusty variable winds are also possible.
Along the coast, marine stratus will hold through the rest of
today and tonight. With high pressure building over the Coast,
may see cigs lower to high IFR overnight tonight. Marine stratus
will also be pushing inland overnight, bringing MVFR cigs to all
the inland terminals after 08Z-10Z. Will hold on to MVFR cigs
through much of Thursday morning, improving to VFR Thursday
afternoon as cigs break up and lift.
KPDX AND APPROACHES...Predominantly VFR conditions through this
evening. Thunderstorms likely to develop near the terminal this
afternoon between 22Z-02Z. During this time, expect gusty,
variable winds from surrounding showers and thunderstorms. If a
thunderstorm moves over the terminal, expect a period of heavy
rainfall reducing flight conditions. Could also see small hail.
Overnight tonight, marine stratus will move into the terminal,
with cigs around 2500 ft. MVFR cigs should hold through much of
Thursday morning, lifting as cigs start to break up by early
Thursday afternoon. -McCoy
&&
.MARINE...High pressure continues to sit over the NE Pac, with
weak gradients over the waters through Friday. As the thermal
low starts to strengthen over norther CA this weekend, we could
see northerly winds ramp up to 20 to 30 kt over the weekend.
Seas remain around 3 to 5 ft through Friday as we remain under
relatively benign conditions. With winds ramping up this weekend,
seas may build up to 5 to 7 ft by late Sunday-early Monday, and
seas may become choppy. -McCoy
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...None.
WA...None.
PZ...None.
&&
$$
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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the CWA or forecast area.
Area Forecast Discussion
National Weather Service Pueblo CO
311 PM MDT Wed Jun 20 2018
.SHORT TERM...(This evening through Thursday)
Issued at 236 PM MDT Wed Jun 20 2018
Chances for showers and thunderstorms look rather low for this
evening. The HRRR shows some isolated precip over the Pikes Peak
region, the Wet mtns and the far southeast plain late this
afternoon, with a batch of precip moving southeastward off the
Rampart Range in the early evening and dissipating about the time it
gets to Crowley county. The HRRR then shows some isolated activity
over Las Animas and Kiowa counties from about midnight to 3 am. The
NAM is somewhat similar. The GFS is similar as well but it also has
precip this evening over some of the Sangre de Cristos. The main
storm threats will be lightning and gusty outflow winds.
Tonight and Thu, an upper level ridge will be slowly building over
the area. The forecast models keep the area dry until late Thu
afternoon, at which point they show just the potential for some
isolated precip over some of the eastern mtns. Temps on Thu are
expected to be around to a few degrees above average, with highs
mostly in the upper 80s to lower 90s over the southeast plains, and
in the mid to upper 80s in the San Luis Valley and the Upper
Arkansas River Valley.
.LONG TERM...(Thursday night through Wednesday)
Issued at 236 PM MDT Wed Jun 20 2018
Long range models are in decent agreement through the extended
period and ensemble spreads are low leading to higher forecast
confidence.
Thursday night through Saturday...expect isolated showers and
thunderstorms to be ongoing Thursday evening, dissipating through
the overnight hours. Lightning will be the primary threat with any
thunderstorms across the mountains. Overnight lows will drop into
the upper 50s to lower 60s.
For Friday, issued a fire weather watch for the western half of
the CWA due to expected low humidity values, gusty winds to near
40 mph and critical fuels. This includes the San Luis Valley,
Continental Divide and Eastern Mountains. Out across the Plains,
humidity values will be elevated due to moisture being advected
from the East. Models in good agreement with a dryline setting up
just east of the I-25 corridor and thunderstorms forming during
the afternoon. A quick moving upper level shortwave trough will
also play a role in thunderstorm development, sending a cold front
south into the Plains by late afternoon. One or two of the storms
could be strong to severe with hail in excess of one inch in
diameter and strong outflow wind gusts. Expect thunderstorms to
shift east across the Plains and clear into western Kansas during
the late evening hours.
By Saturday, the upper shortwave will shift east into the Central
Plains with weak high pressure moving across the area. Drier
conditions are expected through the day with possibly a couple of
isolated mountain thunderstorms during the afternoon. Afternoon
high temperatures will reach the upper 80s to lower 90s across the
lower elevations.
Sunday through Monday...the next upper level storm system will
drop south out of the northern Rockies into Northern Colorado
during this period. Sunday looks to be another near critical day
in terms of fire weather for the western half of the CWA. Again, a
dryline is forecast to set up out near the Kansas border on Sunday
afternoon while a cold front combines with the upper disturbance
passing to the north to trigger thunderstorms across the Eastern
Plains. The strongest storms appear at this time to form in far
Eastern Colorado along the dryline, while frontal thunderstorms
remain confined to the Palmer Divide. How far south thunderstorms
develop along the cold front will depend on where the upper
disturbance tracks. On Monday, a secondary cold front will surge
south across the Plains with more widespread showers and
thunderstorms expected across the region.
Tuesday into Wednesday...high pressure will build northward out of
the Desert Southwest. Models are indicating several areas of
embedded energy rotating around the upper high leading to
diurnally and terrain driven showers and thunderstorms. These
showers and thunderstorms will likely move off the mountains out
into the I-25 corridor during the evening hours, before
dissipating with loss of daytime instability. Temperatures will
also begin to warm with highs reaching the upper 90s by Wednesday.
Mozley
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 236 PM MDT Wed Jun 20 2018
VFR conditions are expected at KCOS, KPUB and KALS. There is a
chance that thunderstorms could end up in the vicinity of KCOS this
evening. Tonight some lower clouds are expected to move into KCOS
and KPUB, but ceilings will probably be between 4000 and 6000 feet
AGL, these clouds should then decrease or dissipate by 14Z Thu.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Friday afternoon through Friday evening
for COZ220-222>225.
&&
$$
SHORT TERM...28
LONG TERM...MOZLEY
AVIATION...28