Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/08/17
Area Forecast Discussion
National Weather Service Bismarck ND
1001 PM CDT Sun May 7 2017
.UPDATE...
Issued at 1001 PM CDT Sun May 7 2017
Lowered pops and slowed down onset of convection with this update.
High res models have been too aggressive developing convection
near the wind shift/surface boundary in western ND, while the most
widespread convection has been much farther west in Montana closer
to the stronger thermal gradient.
UPDATE Issued at 639 PM CDT Sun May 7 2017
No changes to the forecast with the update. Weak radar returns
over the northeast continue to push eastward. Otherwise, the
closest convection remains over far southeast Montana.
&&
.SHORT TERM...(This evening through Monday)
Issued at 359 PM CDT Sun May 7 2017
Forecast highlights in the short term period will be shower and
thunderstorm chances through the period.
Currently, upper level ridge axis over the central Dakotas pushing
east in response to lead embedded S/WV impulses ejecting north-
northeast out of a Desert Southwest upper low and ahead of an
incoming northern stream S/WV now moving into the Montana Rockies.
At the surface, a developing trough is orientated south to north
just west of the ND/MT & SD/WY border. Strong southeast low level
flow ahead of the trough is once again resulting in a windy day
across much of the Northern Plains with a few gusts to around
35-40 mph. Winds taper off some further to the west closer to the
frontal boundary but still breezy. Surface dewpoints have climbed
well into the 40sF along with a few low/mid 50s observed under
this flow regime.
Temperatures this afternoon have been cooler across the north
central and northeast where we have been experiencing elevated
convection the past few hours. Overrunning flow ahead of the
surface trough coupled with mid level instability has led to a few
thunderstorms in this area, though minimal precipitation with
cloud bases rather high. Across the southwest and south central
where a thermal ridge is locating, we have warmed well into the
80s thanks to plenty of sunshine and mixing. Expect we will see a
few 90F degree readings before the day is over.
Thunderstorms currently developing over northeast WY/southeast MT
and the Black Hills region are still projected by high resolution
models to move into or develop 22-01Z into southwestern ND. Aerial
coverage of convection then expands across western ND this evening
along the eastward moving sfc trough as mid level forcing ramps
up. Latest HRRR develops some convection into south central ND
this evening as well. Overall, 0-6KM shear parameters suggest
little chance for organized convection, though MUCAPE values up to
around 1500 J/KG (2500 via the NAM) will offer a window for a few
stronger/marginally severe storms especially late this afternoon
and during the evening.
Showers and thunderstorms continue during the overnight and
through Monday morning as the surface trough/cold FROPA moves
eastward into central North Dakota. Western ND will dry out by 12Z
with clearing skies thereafter.
Noticeably cooler temperatures for Monday in the 60s in the wake
of the precipitation/CAA. Lingering showers east of Highway 83
during the afternoon with the best chances for thunder across the
James River Valley after 18Z. All precpitation activity should be
over by 00Z with high pressure building into the region for
Monday night.
.LONG TERM...(Monday night through Sunday)
Issued at 359 PM CDT Sun May 7 2017
Large closed upper low over the Gulf of Alaska slowly develops
east-southeast into the Pacific NW by the end of the week, then
remains over the west coastal region through next weekend. This
will result in mean ridging over the Northern Plains and a
generally dry and cooler weather pattern. Rather messy with lots
of uncertainty when comparing the GFS/ECMWF so felt comfortable
going with our forecast blend for the long term period. The GFS
does still show some potential for a backdoor cold front late in
the work week, though the ECMWF has ridging aloft now.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 639 PM CDT Sun May 7 2017
Expect showers and isolated thunderstorms developing west this
evening and progressing eastward into Monday morning as a cold
front moves through the region. MVFR ceilings are possible with
this system. Low level wind shear also possible later this evening
at KBIS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JNS
SHORT TERM...NH
LONG TERM...NH
AVIATION...JNS
Area Forecast Discussion
National Weather Service Taunton MA
1027 PM EDT Sun May 7 2017
.SYNOPSIS...
Expect unsettled weather and below normal temperatures into the
first part of the week. Some moderation in temperature and less
risk of showers Friday into Saturday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Broad area of clouds west of a LWM-BOS-EWB line with scattered
but diminishing light showers. Main question for this update is
the amount and timing of any clearing. Most models maintain
enough 925-700 mb layer moisture to suggest partly to mostly
cloudy skies overnight. HRRR low level sky cover suggests
clearing skies while the mid level sky cover shows a band of
clouds lingering along and north of the Mass Pike.
Forecast continues on track. We will maintain a clearing trend
south of the Pike and partial clearing north. Could be isolated
showers after midnight in the cloud area near the northern MA
border.
As for temps... Western MA is already 40-45 with dew points in
the 30s. Min temps, even with the clouds, should reach 35-40.
Temps farther south and east are 45-51 with dew points in the
40s. Cold advection will slowly bring dew points below 40 with
temps reaching the upper 30s and lower 40s.
A few spots in the west may reach 36 degrees, but with the
abundance of clouds in such areas we see a non-zero but really
low likelihood of any frost.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Monday into Monday night...
Cooler than usual as scattered to broken cloud decks filter across
the region with the possibility of some scattered shower activity.
Risk of frost during the overnight hours.
Low chokes off as it continues its occlusion and becomes stacked.
Dry air continuing to entrain as vort-lobe energy continues to
rotate round the center. Though shower chances diminish, a risk
still remains along the W-slopes of high terrain given convergent
forcing of pooling moisture beneath favorable regions of ascent
aloft. Accompanying aiding mechanisms with steeper lapse rates per
building cold pool aloft (H85 temperatures around -4C), especially
during the day with boundary layer destabilization per diurnal
heating. Will keep chance PoPs mostly over N/W MA.
Biggest forecast challenge is frost. Mid to upper 50 highs, again
warmer S/E while cooler N/W closer to the stacked low along with
more favorable regions of low level moisture / clouds and less W
downsloping component. Will cool overnight via cold air advection
and W winds becoming light. Lows drop into the 30s during which
clouds should remain in abundance, however continued scattered
to broken allowing for some partial clearing. FROST ADVISORIES
may be needed for the Tuesday morning period but will give later
shifts a chance to take a look more closely.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
*/ Highlights...
- Below average temperatures through the week
- Diurnal clouds and hit or miss showers each day
- Low confidence on potential coastal low for the weekend
*/ Pattern Overview...
Southern New England will be stuck in a trough pattern through the
work week and into the weekend. 12z model guidance continues with
omega block trend with cut off low into Tuesday. The upper level low
splits off into two with one over the Gulf of Maine and other in
southern Manitoba. This is thanks to building high pressure moving
south from the Hudson Bay. In fact there could be a little bit of
ridging Fri/Sat before western lobes moves back eastward. This is
due to strong riding in the Central CONUS. These lobes will phase
back together over the Great Lakes during the weekend and back over
southern New England by early next week. Continue to watch Pacific
shortwave which will move through the Southern Plains and towards
the Southeast. If this wave gets caught up in the flow, then there
is the potential for a coastal low. Ensembles continue to show a
large spread on this potential so confidence is low at this time.
*/ Details...
Tuesday into Thursday...High confidence.
Cut off low an associated cold pool will be over the region during
this timeframe. This will help keep temperatures below average.
Overall high temps through the medium range will be in the upper 50s
to low 60s. Cooler on the coastlines as winds aloft will be light
resulting in sea breezes especially on Tuesday and Wednesday.
Overnight temperatures will be chilly on Tuesday and Wednesday
night. Any cloud cover during the day will slowly dissipate. Cannot
rule out high level clouds but overall light winds and clearing
skies will help temperatures radiate out overnight. Overnight lows
will dip into the mid to upper 30s, warmer across metro zones.
While each day will generally be dry for each day, steep lapse rates
and enough moisture in the mid-levels could result in diurnal
precip. Better convergence is possible along any sea breeze
boundaries as well. Overall trend will be diurnal hit or miss
showers.
Friday and Saturday...Moderate confidence.
Guidance begins to diverge at this point with the EC and Canadian
bringing in an upper level ridge, while the GFS is more zonal aloft.
Overall, trended towards the EC and have lowered pops a bit on
Friday and especially on Saturday. Still have a risk for a spot
shower or two but the trend appears to be decreasing. Temperatures
aloft will also finally reach above 0C so anticipate surface
temperatures to response, with highs in the low to mid 60s.
Sunday into Monday...Moderate confidence.
Still a large spread in the guidance with potential coastal low. The
GFS is father offshore and quicker compared to the CMC and EC.
Trended towards the ensembles for this period and kept chance pops.
Surface temperatures will also remain in the 60s until guidance
comes into better agreement.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Monday Night/...High confidence.
SCT-BKN low-end VFR cigs. Diminishing west winds tonight,
becoming breezy again Monday with gusts up around 20 kts,
then diminishing Monday night.
KBOS TAF...High confidence in TAF. Isolated showers and runway
wetting possible Monday.
KBDL TAF...High confidence in TAF. Isolated showers and runway
wetting possible Monday.
Outlook /Tuesday through Friday/...Moderate confidence.
Mainly VFR each day with the potential for MVFR within any diurnal
showers. Sea Breezes develops on Tuesday into Thursday.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Monday Night/...High confidence.
Southwest winds shift from the west tonight but lingering gusts
of 20 to 25 knots. The past persistance of S-SW winds will
maintain choppy seas a little longer overnight. Winds will gust
near 20 knots Monday, but seas will diminish. Winds and seas
continue to diminish Monday night.
Small Craft advisories continue overnight and will then drop off
piece-by-piece Monday and Monday night.
Outlook /Tuesday through Friday/...
Light winds across the waters will help keep seas below 5 feet.
Small craft advisories are not anticipated at this time. Southerly
winds on Tuesday will switch to the north by Thursday. Winds
could gust to 20 kts by Friday.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ231>234.
Small Craft Advisory until 8 PM EDT Monday for ANZ235-237.
Small Craft Advisory until 11 PM EDT Monday for ANZ250-254.
Small Craft Advisory until 11 AM EDT Monday for ANZ251.
Small Craft Advisory until 2 AM EDT Tuesday for ANZ255-256.
&&
$$
SYNOPSIS...Dunten/Sipprell
NEAR TERM...WTB/Dunten/Sipprell
SHORT TERM...Sipprell
LONG TERM...Dunten
AVIATION...WTB/Dunten/Sipprell
MARINE...WTB/Dunten/Sipprell
Area Forecast Discussion
National Weather Service Cheyenne WY
728 PM MDT Sun May 7 2017
.UPDATE...
Issued at 728 PM MDT Sun May 7 2017
A line of showers and thunderstorms extends roughly from the
Northern Laramie Range, southeast through Wheatland, and on to
Sidney in Nebraska at this hour. A few isolated storms exist out
north ahead of this line as well, with storm motion to the
northeast. Look for moderate rain, occasional lightning, and gusty
winds to 40 mph with this activity as it should last through
about midnight. Increased PoPs and QPF mainly for northern and
eastern portions of our forecast area to account for this line. A
cold front looks to start its trek southward across our counties
shortly before sunrise. Winds will shift to the north and gust 25
to 30 mph for a period after frontal passage.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 300 PM MDT Sun May 7 2017
Water vapor imagery showing pronounced closed low over southern
California this afternoon. Seeing some shower/thunderstorm
activity developing over Colorado in the southerly flow ahead of
this low. Dewpoints have been increasing along the southern Front
Range, extending up into the Panhandle this afternoon. Alliance
reporting a 50 Td and Sidney reporting 48. Latest SPC Mesoanalyst
page showing surface based CAPE from northeastern Colorado to most
of eastern Wyoming east of the Laramie Range around 700-1000 J/Kg.
Looks like the morning HRRR forecast caught on pretty good with
the convective initiation this afternoon. Was almost spot on in
timing of convection near Cheyenne. Its forecast is for blossoming
shower and isolated thunderstorm development east of the Laramie
Range through the afternoon. Still have a small cap out in the
Panhandle where convective inhibition is around -25 to -50 J/Kg.
This cap should break later on this afternoon and what the HRRR is
advertising looks fairly reasonable. Will likely need to increase
PoP coverage before sending out the afternoon package for later
this afternoon and early evening.
Better chances for precip Monday as upper low tracks into Arizona
and New Mexico Upper level diffluence Monday afternoon. This will
interact with increasing low level moisture pooling into the east
slopes of the Laramie Range and pieces of energy being pinwheeled
off the low in our area. Not convinced yet that severe
thunderstorms are going to be an issue Monday afternoon/evening.
Am more concerned with low storm motions and PWATs approaching .8
inches on GFS sounding. Could be looking at a heavy rain event for
portions of the southern Panhandle and I-80 Corridor from Pine
Bluffs to Cheyenne. Especially Monday evening, when GFS, ECMWF and
SREF showing around a half inch QPF bullseye for this area.
.LONG TERM...(Wednesday through Sunday)
Issued at 300 PM MDT Sun May 7 2017
Wednesday...Slow moving upper low tracks from west central New
Mexico to south central Colorado with deep moist upslope flow across
our forecast area. Looks like enough moisture and instability for
scattered to numerous showers and isolated thunderstorms. Relatively
cool with the cloud cover and showers.
Thursday...A bit warmer with less cloud cover and showers. Upper low
progged to move to southern Kansas with shortwave ridging aloft
building across Wyoming. Showers decreasing in coverage during the
day with limited coverage in the afternoon and evening.
Friday...Shortwave ridging aloft will limit shower and thunderstorm
development, though looks like enough low and mid level moisture for
isolated showers and thunderstorms over and near the mountains.
Warming trend continues with less cloud cover and precipitation.
Saturday...Shortwave ridging moves to eastern Wyoming with low level
upslope limiting warming trend. Looks like enough low and mid level
moisture for isolated to scattered afternoon and evening showers
near the mountains.
Sunday...Flow aloft turns southwest in advance of the western U.S.
trough. This will strengthen the low level upslope and help produce
more cloud cover and more coverage of afternoon and evening showers
and thunderstorms, especially along and east of Interstate 25. More
cloud cover means slightly cooler temperatures.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 421 PM MDT Sun May 7 2017
Wyoming TAFS...VFR prevails, with isolated thunderstorms until
02Z, and occasional IFR or MVFR from 09Z to 15Z. Wind gusts to 23
knots until 02Z, and to 25 knots after 19Z Monday.
Nebraska TAFS...VFR prevails, with isolated thunderstorms until
03Z, and occasional MVFR at Chadron and Alliance from 10Z to 15Z.
Wind gusts to 22 knots through 03Z, and to 25 knots after 19Z.
&&
.FIRE WEATHER...
Issued at 300 PM MDT Sun May 7 2017
Fairly dry this afternoon, but we are seeing increasing moisture
moving in from the south. This moisture is the result of a low
pressure system over the desert southwest pulling moisture north
into the Rockies. As this low moves inland, we expect low level
moisture to increase. Low level moisture also being pulled in
from the Gulf of Mexico in low level southeast winds along the
Front Range. Next couple days look for increasing chances for
wetting rains and isolated thunderstorms each afternoon and
evening. With greenup in progress and increasing low level
moisture increasing chances for wetting rains, fire weather
concerns are minimal.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...RJM
SHORT TERM...GCC
LONG TERM...RUBIN
AVIATION...RUBIN
FIRE WEATHER...GCC
Area Forecast Discussion
National Weather Service Glasgow MT
832 PM MDT Sun May 7 2017
.SHORT TERM...for northeast Montana...tonight through Tue...
8PM UPDATE:
Changes to the forecast were to raise PoP totals and coverage.
Rain showers are rapidly making their way across the CWA on radar
echo trends. Previous NAM forecast soundings are placing two to
three times more CAPE across the area than what was observed in
this afternoon soundings. HRRR seems to have caught on to the
increased coverage but lower convection in addition to the
developed line across the western to central portions of the CWA.
GAH
PREVIOUS SHORT TERM DISCUSSION
The upper-level ridge axis will be positioned through North
Dakota to begin this evening, while the energetic northern portion
of the Western split-trough swings across the Divide. The cold
front in advance of the trough will be moving east through the
eastern half of the local CWA. With peak heating and moderate
convection, thunderstorms and rain showers are expected to already
be in progress. With the surface trough shoved into the Dakotas,
the cooler air behind the front will energize winds from the
northwest, sustaining the NPW for Fort Peck Lake this evening.
Models continue to be in flux with the QPF, suggesting most will
go north and east. With the CAA, expect overnight lows to run 15F
to 20F degrees cooler for the western counties.
Monday will continue with the cooler temperatures, actually just a
return to normal. The overnight showers may linger in the morning
near the North Dakota border, but expect clearing from the west.
Winds will diminish Monday night while a narrow and shallow ridge
rides over the area. Clearing skies will allow more overnight
cooling.
Tuesday the models pick up a shallow, weak short-wave trough
along the international border. The associated front with this
wave is expected to remain south of our area, but possibly
allowing some shower activity to drift north near the Yellowstone
River Valley. Temperatures may also creep up slightly over Monday.
Templer
.LONG TERM...Tue night through Sun...
Not too many changes made today. Tried to update temperatures,
humidity and winds for Fire Weather customers. Basically dry
through much of the week with a warm up and the next chance of
showers next weekend. TFJ
PREVIOUS LONG TERM DISCUSSION:
Synoptic Setup: The long range begins with a Zonal flow over the
northwest quarter of the CONUS including Eastern Montana. South of
here Hot air stretches from northern California to Colorado.
SOuth of that airmass is a closed low over the Baja and southern
Arizona. Farther west another closed low sets over the Gulf of
Alaska.
Monday night through Tuesday Night: The closed low to the south
will push north forcing the hot air to the south top move into
western Montana as a ridge and forcing a weak trough in response
over northern Wyoming and southwestern Montana. Any jet moving
through the flow will latch onto this and generate a lift profile
in these locations. This will keep the bulk of the shower
activity to the south with perhaps and isolated shower moving
through the Yellowstone Valley.
Wednesday through Friday: Developing ridge to the west will get a
reinforcing shot of hot dry air from California and amplify this
ridge will slowly progress across Montana and raise temperatures
to above normal while keeping skies clear to partly cloudy and
dry. The ridge itself amplifies considerably for Friday with much
higher temperatures over the previous forecast.
Friday night onward: Trough from the Gulf of Alaska will make it
push across the Pacific Northwest. This should force the ridge
axis over the CWA Friday night and may spark off some
thunderstorms with embedded severe elements. Saturday onward
becomes a bit more fuzzy as model ensembles break and the trough
may move through, or flatten the ridge and take the bulk of the
cold air north, or rip itself apart and bounce of the ridge while
staying in place. Every one of these scenarios means increased
precipitation but the spread also keep surface temperatures in
flux for the long range. GAH
&&
.AVIATION...
FLIGHT CAT: VFR, brief MVFR is possible tonight in lower ceilings.
SYNOPSIS: Scattered thunderstorms will move northeast across the
area this evening and the early morning. Otherwise, lower ceilings
will move east into the area this evening, brief MVFR levels are
possible.
WIND: NW will increase to 15-25 kts with higher gusts through
Monday afternoon... becoming light and variable that evening.
GAH
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory until 3 AM MDT Monday For Fort Peck Lake for
Central and Southeast Phillips...Central and Southern Valley...
Garfield...McCone...Petroleum.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
731 PM MDT Sun May 7 2017
.SHORT TERM...(Tonight through Monday night)
Issued at 425 PM MDT Sun May 7 2017
Cutoff low over southern California will be meandering slowly
eastward over the next few days. This will keep deep difluent
southerly flow in place with ejecting waves lifting through the
forecast area. Have seen a few stronger storms today with several
reports of pea up to quarter size hail. The strongest cell popped
north of Rangely and broke from the flow, turning right toward
Blue Mountain. Storm showed some rotation with long lived and
persistent hail path per MESH products.
On that note, convection likely to persist through this evening
with HiRes models in good agreement keeping activity focused on
the northern zones. Southern zones will be more isolated in
coverage through this evening. Convection diminishes after
midnight, but not expected to totally shut down. Latest HRRR and
RAP13 showing some activity firing near the Four Corners between 3
and 6 am, although confidence no extreme. So will keep pops on the
low side for now.
Monday should be an interesting day as we see an old frontal
boundary set up along the I-70 corridor with energy rotating
northward during the morning and early afternoon hours. NAM CAPE
values in excess of 1500 J/kg by midday along and just north of
the surface front. Steep lapse rates, instability, forcing and
difluence aloft will get storms rolling early with activity
persisting through the afternoon hours. SPC currents showing this
area in marginal severe, which looks reasonable with the above
parameters in play.
Temperatures will be tricky with cloud cover from developing
convection shading some areas. This will also play a role in our
convection through the day with the strongest storms firing along
the edges of denser cloud cover.
.LONG TERM...(Tuesday through Sunday)
Issued at 425 PM MDT Sun May 7 2017
The deep upper low will be lifting toward the Four Corners Tuesday
and Wednesday with a stronger wave lifting northward Tuesday and
Tuesday night. Cooling aloft associated with the upper low should
drive snow levels down over the San Juans by Tuesday night with
showers spreading from south to north through the day. EC and GFS
have come into better agreement with this scenario with the low
arriving over the Four Corners by midday Wednesday. As with many
closed lows, the exact timing of the kick-out will play a critical
role in our precipitation forecasts, so while ramping things up,
not quite ready bite off on the heavier QPF forecasts that a few
models are showing. Influence from this system is expected to
diminish on Thursday with dirty ridge sliding into place Thursday
night and Friday with continued unsettled weather. Flow then backs
to the southwest over the weekend with drier and warmer weather
returning. Although winds will likely be picking up in the drier
air mass as we mix deeper aloft.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 731 PM MDT Sun May 7 2017
Scattered showers and thunderstorms will decrease during the
remainder of the evening with just a few light showers lingering
past midnight. There is a slight chance that additional showers or
thunderstorms will impact TAF sites directly during the remainder
of the night. However, CIGS should remain above ILS breakpoints
and VFR conditions are expected to prevail through 00Z/Tuesday.
Scattered showers and thunderstorms redevelop over the higher
terrain again Monday afternoon.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...JDC
LONG TERM...JDC
AVIATION...NL
Area Forecast Discussion
National Weather Service North Platte NE
633 PM CDT Sun May 7 2017
.SHORT TERM...(This evening through Monday)
Issued at 325 PM CDT Sun May 7 2017
Continued from previous forecast, a slight chance for showers and
thunderstorms for areas mainly south of highway 2 this evening.
The HRRR and RAP model continue to indicate development
northeastward through late evening, then diminishing or ending
around midnight. Given the dry lower layer, gusty winds up to 50
mph will be possible. Coverage should be mostly isolated.
Monday, a cold front will push through the forecast area and usher
in somewhat cooler temperatures, with highs from the low to mid
70s northwest to lower 80s southeast. The balance of the day looks
dry, as thunderstorms begin to develop in eastern Colorado well
upstream of a closed low situated over Baja Mexico.
.LONG TERM...(Monday night through Sunday)
Issued at 325 PM CDT Sun May 7 2017
Chances for showers and thunderstorms remain in the forecast
Monday night through Tuesday night similar to the previous
forecast. A well defined disturbance will lift north Monday night
within very amplified flow established from the Desert Southwest
and Southern Great Plains. The best chances will be across the
southwestern half of the forecast area. There is a marginal risk
for severe thunderstorms monday evening south of Chappell through
Hayes Center where better shear and instability will reside.
Chances for showers and thunderstorms continue on Tuesday, but
increase Tuesday night as the upper low moves from Arizona into
western New mexico overnight. Diffluent flow aloft will promote
increasing convection overnight. Chances continue Wednesday, but
mainly showers with isolated thunderstorms south. Another round of
showers are likely across the southern half Wednesday night north
and west of a closed low tracking from northern New Mexico into
southwest Kansas. Rainfall amounts could range from a half inch or
more south of I80. On Thursday, the closed low will continue
eastward across Kansas, with showers chances across the south
diminishing or ending during the day.
Highs Tuesday from the upper 60s to lower 70s Tuesday, fall into
the low to mid 60s most areas for Wednesday and Thursday. Upper
ridging builds in Friday through Sunday, especially according to
the 12z European model. The GFS indicates weaker ridging and more
unsettled with the forecast keeping low chances for showers or
thunderstorms Saturday and Sunday for some areas. The weekend
however looks mainly dry with highs mainly recovering into the
lower 70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 626 PM CDT Sun May 7 2017
For this evening, expect scattered to broken high cloudiness
across western and north central Nebraska. Skies will clear out
overnight with scattered clouds ranging from 20000 to 25000 FT AGL
on Monday. Winds will shift from the south to the west, then north
on Monday. Wind speeds by afternoon will approach 20 KTS across
northern Nebraska, with speeds ranging from 10 to 15 KTS across
southern Nebraska.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Roberg
LONG TERM...Roberg
AVIATION...Buttler
Area Forecast Discussion
National Weather Service Lubbock TX
631 PM CDT Sun May 7 2017
.AVIATION...
VFR with mostly clear skies through the night should collapse to
MVFR (possibly IFR at times) after sunrise at LBB and PVW as
breezy SE winds moisten. Indications are MVFR stratus should
persist all day on the Caprock, with mostly VFR cloud decks
favored at CDS. Any TS this evening through Monday are favored
well west of LBB and PVW, with movement to the north.
Otherwise, low level speed shear around 600 feet will again
develop toward midnight on the Caprock and decay by daybreak.
&&
.PREV DISCUSSION... /issued 313 PM CDT Sun May 7 2017/
DISCUSSION...
Visible satellite shows our Meandering Desert Low (MDL) spinning
near Los Angeles, CA this afternoon, and RAP analysis shows it very
slowly drifting southward. This position is in good agreement
with models, which currently are in excellent agreement with each
other on the continued development and movement of this system.
Water vapor imagery shows a modest plume of mid-level moisture
across mainly our western forecast area this afternoon, which will
be useful for possible thunderstorm development late this
afternoon and evening near the TX/NM border. The main threats with
storms that do develop today will be hail and damaging winds, as
sounding analysis shows an uncapped environment with an inverted-v
classic of downburst winds.
Continued return of moisture for Monday will help to spread
thunderstorm chances a bit further east, even though the dryline
will stay well back into central NM. Storms will have a cap to
contend with, however, plenty of CAPE and shear will be available
for the taking should that cap erode. The MDL will still be wobbling
around the Desert Southwest this day.
Tuesday becomes much more interesting as the MDL finally begins to
eject eastward. Ample moisture will be set in place over the area,
in fact, this is one complicating factor of the forecast. Low clouds
could limit surface heating during the day, thus reducing some of
the instability for afternoon convection. Models show the dryline
starts to push east Tuesday evening but appears to retreat before
making its full surge eastward on Wednesday morning with the aid of
energy from the MDL, which will be located roughly over central NM.
Late Tuesday, effective shear values begin to climb to the 45-50 kt
range across the western half of the forecast area, reaching upwards
of 60 kt by 9Z Wednesday. These shear values do spread across most
of the area throughout Tuesday night. Diagnosing CAPE...GFS sounding
analysis shows a band of around 1500-1800 J/kg across the western
half of the CWA late Tuesday spreading eastward overnight. With this
being an overnight event, it is a bit suspect whether we can hang
onto that much CAPE throughout the night. Included in the soundings
are low LCLs and mid-level lapse rates approaching 8.5 degrees. This
all makes for a possible sleepless night for many on the South
Plains with the threat of severe weather through the night and
morning hours. While the main threats will be large hail and
damaging winds, the possibility of tornadoes cannot be ruled out,
especially across the western and central South Plains. Once the
dryline punches through, however, the severe threat will diminish
quickly. The exact timing of the passage of the low on Wednesday
is one disagreement the models have, and that could affect precip
chances Wednesday afternoon. By Wednesday evening, most of the
forecast area should be clear of precipitation, awaiting the cold
front that will wrap around on Thursday.
Thursday, the cold front pushes through giving us a cool day on
Friday. However, a ridge quickly builds in on Saturday, and we
return to warm temperatures for the weekend.
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
93
Area Forecast Discussion
National Weather Service Norman OK
954 PM CDT Sun May 7 2017
.UPDATE...
Forecast looks to be on track in general.
&&
.DISCUSSION...
We`ve only made some minor tweaks to hourly grids this evening as
temperatures cooled quickly in some areas. But current trends,
HRRR and RAP still support minimum temperatures within a degree or
two of the forecast and resulted in only small changes to the
forecast lows.
&&
.PREV DISCUSSION... /issued 621 PM CDT Sun May 7 2017/
AVIATION...
08/00Z TAFs. VFR conditions will continue through forecast period.
Generally moderate south-southeast winds will also continue. Some
afternoon cumulus expected tomorrow with continual and slow
increase in moisture.
PREV DISCUSSION... /issued 140 PM CDT Sun May 7 2017/
DISCUSSION...
The upper ridge and warm air will last into mid-week. Moisture
will gradually increase into Wednesday. A closed upper-level low
will slowly move toward Oklahoma and be positioned over northern
NM Wednesday when winds aloft increases coincident with the
moisture increase. A dryline will develop over the central TX
panhandle and move into western OK late in the afternoon or early
evening. Rain, thunderstorms, and severe thunderstorms are
expected into the night. The following surface cool front will
move into northern OK Thursday, but the dryline is expected to be
near or east of I-35 and set the stage for another day of
thunderstorms over southeast and east central Oklahoma. The upper
low is expected to weaken and move east of OK/KS later Thursday.
Warming conditions underneath another upper ridge will take its
place over the southern OK into the weekend.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 59 81 61 81 / 0 0 0 0
Hobart OK 59 81 62 80 / 0 0 0 10
Wichita Falls TX 59 83 63 82 / 0 0 0 0
Gage OK 59 81 60 81 / 0 0 10 10
Ponca City OK 57 82 60 83 / 0 0 0 0
Durant OK 59 81 61 81 / 0 0 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
Area Forecast Discussion
National Weather Service Raleigh NC
920 PM EDT Sun May 7 2017
.SYNOPSIS...
Cool high pressure will build in from the northwest tonight through
Monday. A warm front will move into the area from the southwest on
Tuesday and then stall over the Carolinas through mid week.
&&
.NEAR TERM /through tonight/...
As of 920 PM Sunday...
Skies have generally cleared out in the wake of a weak mid level
shortwave trough now pushing eastward off the Mid Atlantic coast,
although the continued presence of an upper jet streak across NE NC
and SE VA may allow patchy mid clouds to persist in our NE into the
night. Otherwise, expect skies to stay mostly clear overnight. Winds
have already diminished across the area, making for good radiational
cooling conditions as they stay very light or calm under minimal
cloud cover. Temps are running near to a few degrees below the
forecast pace, with dewpoints similarly a tad cooler than earlier
expected, so will adjust lows down a couple of degrees, especially
in the normally cooler spots which have already fallen into the
lower 50s. Lows 42-49. -GIH
Previous discussion from 145 pm: A few sprinkles remain possible in
the far NE Coastal Plain early this afternoon as additional
shortwave energy digs SE along the western periphery of an upper
level trough beginning to lift NE away from the region. Otherwise,
high confidence in dry conditions through tonight. After scattered
diurnal Cu (at ~5 KFT) dissipates within 1-2 hours of sunset, expect
clear skies overnight as subsidence strengthens in the wake of the
departing upper level trough. Expect highs in the mid/upper 60s to
lower 70s, warmest south. With a dry airmass in place, clear skies,
and winds becoming calm within an hour or two after sunset, strong
radiational cooling will yield relatively chilly low temperatures
Monday morning, in the lower to mid 40s, with a few rural/low-lying
areas possibly bottoming out in the upper 30s. -Vincent
&&
.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 145 PM EDT Sunday...
NW flow aloft will strengthen over the region Mon/Mon Night as the
aforementioned upper trough continues to lift NE away from the
Carolinas. Expect dry and mostly sunny or clear skies during the day
with highs in the upper 60s to lower 70s. Strengthening low-level
warm advection from the west will result in a narrow NW-SE oriented
band of frontogenesis extending SE from IL-IN-KY into northwest NC
by 12Z Tue morning. Additionally, small amplitude waves /DPVA/ in NW
flow aloft are progged to track SE directly over the strengthening
low-level baroclinic zone, resulting in the development of multiple
(albeit weak) waves of low pressure along the strengthening frontal
zone. As such, expect increasing cloud cover from the NW overnight,
with a good chance for light rain in the W/NW Piedmont by sunrise
(08-12Z Tue). Sprinkles or light rain may extend ESE to the Triangle
and northern Piedmont by ~12Z, though chances there and elsewhere
will increase most significantly after 12Z Tue. Expect lows ranging
from the lower 40s in the far NE Coastal Plain to the mid/upper 40s
Triangle south and west. -Vincent
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 300 PM EDT Sunday...
...Unsettled weather through the period...
The persistent omega block will begin to shift eastward on Tuesday
with the upper low shifting east over the Canadian maritime as
heights increase aloft as shortwave ridging builds in from the west.
Forecast details for the mid to late week period are murky at best,
highly contingent on small-scale/mesoscale disturbances tracking
through the region within the NW flow aloft and atop a NW to SE
quasi-stationary and wavy frontal zone forecast to extend from the
Upper MS valley southeast invof the Carolinas. Given that mesoscale
features, such as nearby convection and convective outflow will
strongly influence/augment the nearby frontal zone, it is just too
early to discern the exact location of the front. Thus confidence in
forecast details is low at this time. While pops will largely be
dependent on the timing of any disturbances diving SE through the
region, scattered showers and possibly thunderstorms will be
possible day and night, with convection likely to exhibit a diurnal
signal with greatest coverage during strongest daytime heating.
WRT temperatures, expect a rather sharp northeast to southwest
temperature gradient where ever the front meanders, ranging from
lower 70s north of the front to lower/mid 80s along and south of the
front. Will maintain chance(30-40%)pops everywhere due to the
aforementioned uncertainty/low confidence. Additionally, with
central NC on the southern/southwestern periphery of the upper low
and associated strong mid-level jet, 40 to 50 kts of deep layer
shear will be more than adequate in the presence of sufficient
instability to support strong to severe storms, including a
conditional probability for a few supercells with models showing a
nearby EML plume that could result in moderate to possibly strong
instability across the far southern zones. Uncertainty is just too
great at this time to mention in HWO. By late Friday and into
Saturday, stronger synoptic scale forcing with the approach of the
former closed low over the SW US and possible interaction/phasing
with a northern stream trough/low out of Canada, should yield the
greatest convective pops and possibly best severe threat, with the
front still progged to lie in close proximity.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 725 PM EDT Sunday...
24 Hour TAF period: Winds are the forecast problem of the day but
high confidence in VFR conditions through the TAF period. Skies
should remain mostly clear for the duration of the TAF period. There
was some lower visibilities approaching MVFR levels in the HRRR but
these are largely unsupported by the SREF, MOS Guidance and expected
dewpoint depressions. If we were to see some rogue MVFR visibilities
the most likely location would be KRWI but fairly high confidence
that this won`t happen.
Regarding the winds, some gustiness remains across the area this
afternoon but these gusts will subside closer to sunset. Then expect
5 kts or so out of the west northwest until after sunrise Monday
when gusts will once again pick up around 15z or so. Expect
sustained winds to remain fairly high as well at 10-15 kts gusting
to 20-25 kts. Gusts on Monday afternoon are expected to relax near
the end of the TAF period.
Long Term: Weather should remain quiet until
Tuesday when a shortwave in the upper flow approaches from the
northwest and could bring some precipitation to the area.
Frontogenesis over the region for an extended amount of time will
bring the threat for adverse conditions for the end of the work week
and through the weekend.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Hartfield
NEAR TERM...Hartfield/Vincent
SHORT TERM...Vincent
LONG TERM...CBL
AVIATION...Ellis