Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/10/17
Area Forecast Discussion
National Weather Service Denver/Boulder CO
628 PM MDT Tue May 9 2017
.UPDATE...
Issued at 625 PM MDT Tue May 9 2017
Updated evening forecast grids to better resolve convection firing
along a convergence line that radar has been showing sitting
nearly stationary east-southeast of the Denver metro area past
couple of hours. Strongest storm going up just southeast of KDEN
has should some sign of turning northwestward and therefore may
pass over the airport and northeast metro area in the next
several minutes. May see a brief moderate shower and gusty winds
at KDEN as it passes by. Otherwise not much else as mesoscale
models show this storm activity tracking northeast rest of the
evening and eventually collapsing into light showery precip on the
plains. I`ve also removed mention of heavy rainfall tonight as
the environment doesn`t look all that supportive for that...but
still quite abit of moisture around. That said, should see skies
fill and cloud bases lower after midnight as winds gradually turn
north-northeast with arrival of a cold front in the denver area
around 10z tonight.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 354 PM MDT Tue May 9 2017
The low pressure system centered over southern Arizona continues to
drive moist southerly flow into CO. Coupled with a deformation zone
developing over northern CO, there is a chance for widespread
showers overnight in the CWA. The threat for severe weather has
significantly decreased over the region this afternoon with the low-
level cloud cover hindering convection. Main threat this afternoon
into the evening is heavy rain but some small hail is still possible
as sufficient CAPE and shear should remain, with highest values east
of the urban corridor extending northeast into the plains. Models
indicate that PW values could exceed 1 inch in some areas across the
eastern portion of the CWA. This is above the 90th percentile for
this time of year. This abnormally high PW will increase the threat
for heavy rain, although large uncertainty exists as to where
development will occur. NAM and GFS are trying to develop an MCS
that moves from southern Colorado tonight north into NE CO by
morning, favoring higher QPF in the area. RAP and HRRR are more
reluctant to develop this feature and thus have lower QPF amounts.
Nevertheless, wherever convection does develop, difluence and
lower wind speeds aloft will produce slow-moving storms that could
produce locally heavier amounts from 0.25-0.75 in/hour.
Tomorrow, the large storm system over AZ will continue to move
northeast but the low-pressure center will remain south of CO
through the afternoon. Southerly moisture transport and a
developing frontal boundary will be dominant factors in producing a
higher chance for widespread showers throughout the day. Again, a
fair amount of uncertainty exists in the forecast as models are
disagreeing on where the front will develop as well as trough
placement aloft and upper-level divergence. In addition, forecast
soundings at this time indicate mid-level drying, which would reduce
the chance for heavy precipitation. Northerly surface flow and
cloud cover should keep high temperatures across the plains in the
mid- to upper 50s, which is about 10 degrees below the
climatological average.
In the higher elevations, high temperatures will be in the upper 30s
to lower 40s. Right now, snow levels are around 11,000 feet but are
expected to drop to 9000-10,000 ft tomorrow in the northern
foothills with some area receiving 3-7 inches of snow over the next
24 hours.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 354 PM MDT Tue May 9 2017
Wednesday night through Thursday the slowly moving cutoff low
should make it to the Oklahoma and Texas Panhandles by the
afternoon, resulting in a continuation of moist upslope flow and
synoptic scale lift through midday. Highest pops will be Wednesday
night then taper off after sunrise. The models differ on the
progression of the trough, with the ECMWF being more progressive
and absorbing the trough into the NW flow by Thursday afternoon.
NAM and Canadian models are slowest moving the low across N.
Oklahoma Thursday afternoon...GFS is in between. Despite model
differences feel the mountains and I-25 urban corridor will be dry
from midday and on, while further east across the far eastern
Plains the rain should exit by mid to late afternoon. Temperatures
across the Plains will remain on the cool side given the
remaining moisture, northeast upslope, and expected cloud cover,
with temps in the upper 50s to low 60s expected across the
Plains. The mountains should warm significantly compared to
Wednesday given warm advection at 700 mb as the ridge
approaches...700 mb temps over the mountains warm 5-7 degC over
Wednesday so expect highs Thursday in the 50s and 60s.
On Friday the storm is well east of the area and a ridge axis sets
up directly over Colorado by Friday afternoon. Warm and dry area
wide with temps in the mid 70s across the Plains and 60s and 70s
in the mountains and foothills. On Saturday the ridge axis shifts
east putting Colorado in southwest flow, and downsloping will
boost Plains temperatures into the low 80s. Mountains temps will
be similar to Friday`s readings. Some of the models generate
mountain showers/thunderstorms Saturday afternoon so have
including a slight chance of diurnal thunderstorms there. Do not
expect rain to reach the surface east of the mountains.
Sunday and Monday southwest flow continues across the state as a
series of Pacific storms carves out a long wave trough across the
Great Basin. Several short wave troughs rotate around the long
wave trough. At this time the models indicate dry conditions
state wide on Sunday as there is very little moisture to work with
given trajectories from off the coast of Baja CA. Given the
source of the air and lack of good moisture...warm, above average
temperatures area-wide will continue Sunday and Monday. General
agreement among the long range models that one of the short wave
troughs brushes the northern half of the state Monday, which
results in a chance of showers and thunderstorms for the northern
mountains. Snow levels look to remain above 9kft Sunday and
Monday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 625 PM MDT Tue May 9 2017
Chance of t-storm with brief moderate rainfall and gusty winds at
KDEN now through 0050z. Otherwise, the chance of thunderstorms in
the Denver area should gradually diminish through the evening.
Overnight, a cold front is forecast to slip south through the
metro area around 10z. northerly winds behind the front will usher
in lower clouds and light precip. Could see mvfr conditions will
lower to IFR conditions after 10z at Denver area airports.
&&
.HYDROLOGY...
Issued at 354 PM MDT Tue May 9 2017
There will continue to be heavy rainfall potential from
convective storms from today through Wednesday, then more
stratiform rainfall late Wednesday night and Thursday. Model QPF
is quite varied but still generally in the 1-2 inch rainfall range
while GFS showing 2-3 inches of rainfall by late Wednesday. Slow-
moving storms that could produce locally heavier amounts from
0.25-0.75 in/hour. At this time based on QPF outputs not
expecting any major flooding from rainfall forecasts and current
runoff projections through the end of the week. If there are more
localized convective rainfall which occurs over similar areas over
the next few nights, than those areas may need to be monitored
closely. Two areas of concern are over northwestern Adams County,
northeastern Elbert, northwestern Lincoln and southern Washington
counties, as well as central Weld county near Greeley.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Baker
SHORT TERM...Stovern/Kriederman
LONG TERM...Schlatter
AVIATION...Baker
HYDROLOGY...Kriederman
Area Forecast Discussion...Updated
National Weather Service Billings MT
907 PM MDT Tue May 9 2017
.SHORT TERM...valid for Wed and Thu...
Minor update to trim precipitation chances over northern and
western zones. Still a few showers and working south from near
Billings, heading toward the Pryor mountains. HRRR tracks these
toward Sheridan in an hour or two. Precipitation over eastern
zones really diminishing quickly with sunset so cut back to slight
chance. Rest of the forecast on track. Chambers
.LONG TERM...valid for Fri...Sat...Sun...Mon...Tue...
Ridge axis will be over the forecast area to begin the extended
period on Thursday. Currently have high temperatures in the low to
mid 80s on Thursday and Friday afternoon while the ridge axis is
overhead. This will likely bring about another round of snow melt
in the mountains. Widespread flooding is not anticipated, but with
higher flows already in place, we`ll likely see some small rises
along area rivers and streams this coming weekend as the water
works its way downstream.
Good model agreement that an upper level low will begin to move
into inland portions of the western US over the weekend. As this
low drifts east, the ridge axis will be displaced to the east and
the cooler and more unsettled weather will return to the region
over the weekend. Best rain chances will be over the mountains and
western zones (west of Billings and Roundup) on Saturday but then
begin to affect central and eastern zones on Sunday and Monday as
the low slowly slide eastwards. Temperatures will return into the
upper 60s and low 70s by the weekend with increased cloud cover
and higher chances for showers and thunderstorms. These
seasonable temperatures should also slow the snow melt across
area mountains.
Looking past the weekend, model ensemble guidance and current
outlooks from the CPC keep the weather fairly active across the
region with above normal chances for rain and temperatures near
average. The confidence in these conditions is above normal given
the good agreement in the model ensemble members. Dobbs
&&
.AVIATION...
Showers and isolated thunderstorms will gradually diminish across
the area this evening. Recent rain will allow fog to develop
across portions of far southeast Montana overnight causing local
IFR to LIFR cigs and vsbys. VCFG is possible near KMLS overnight,
although confidence is low at this time. Elsewhere, VFR will
prevail into Wednesday. STP
&&
.PRELIMINARY POINT TEMP/POPS...
Wed Thu Fri Sat Sun Mon Tue
-----------------------------------------------------------
BIL 045/072 048/080 052/084 052/070 046/067 046/069 047/069
20/U 00/U 10/U 13/T 42/T 32/T 33/T
LVM 038/072 043/078 047/080 045/066 039/064 039/066 040/067
00/U 01/U 12/T 23/T 22/T 22/T 33/T
HDN 042/073 046/081 050/086 050/075 047/071 047/071 047/073
20/U 00/U 00/U 02/T 31/B 33/T 33/T
MLS 044/072 048/080 052/086 053/075 050/071 049/070 050/071
10/U 00/U 00/U 01/U 31/B 35/T 43/T
4BQ 041/069 045/077 048/083 049/076 047/071 047/071 047/074
20/U 00/U 00/U 11/U 31/B 54/T 42/T
BHK 039/069 044/075 047/080 046/073 046/068 045/065 046/067
10/U 00/U 00/U 00/U 31/B 44/T 44/T
SHR 039/067 041/075 046/082 046/073 044/068 043/068 043/070
20/B 00/U 00/U 12/T 32/T 42/T 32/T
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.
&&
$$
weather.gov/billings
Area Forecast Discussion
National Weather Service Dodge City KS
710 PM CDT Tue May 9 2017
.UPDATE...
Issued at 710 PM CDT Tue May 9 2017
Updated grids through the early morning hours to reflect severe
thunderstorm watch in effect for Grant, Hamilton, Kearny, Morton,
Stanton and Scott counties through 2 am CDT. Not expecting much
activity through 9 pm or so. HRRR solutions have been consistent
with a loosly organized squall line arriving on the CO/KS border
around 11 pm. HRRR shows the line of showers and storms decreasing
in intensity near Garden City and Liberal by 1 am. Linear mode of
convection suggests wind gusts of 50-60 mph are the primary
threat, although any discrete cells along/ahead of the line may
produce up to ping pong ball sized hail.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 237 PM CDT Tue May 9 2017
A couple of isolated showers have developed in the more robust
updrafts over the rapidly developing cu field across southwest
Kansas this afternoon. However the more numerous showers are
relegated to the higher terrain area of NM/CO/TX and OK panhandles.
surface upslope. Ongoing convection across the southern Rockies into
the southern Colorado front range will be the primary source for
convection affecting western Kansas later tonight and possibly in
the overnight timeframe. Models vary considerably between the HRRR
and NAM with respect to convection. The HRRR would drive storm
clusters north tying into the the surface front/surface low
pressure region across northwest Kansas after 02 UTC. The recent
NAM runs split the area between the convective sources, holding
off storm chances until Wednesday morning after 12z, associated
with the southern Plains elevated convection. Additionally, the
NAM develops an Elkhart surface low tied to a dryline southward
across the Panhandles by the afternoon hours on Wednesday. The
greatest risk from severe should be associated with this late day
potential of storm developing in the far southwest, with hail
greater than 2 inches, damaging wind and tornado potential.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 237 PM CDT Tue May 9 2017
The upper low now over southern Arizona will lift into the southern
High Plains Wednesday night. This should place our area in the cold
conveyor belt region of the synoptic storm, with cold advection and
north winds, and chances for rain showers heading through Thursday
evening. This may relegates most of the area to the 60s on Thursday
at most, or even cooler 50s following the much cooler NAM and
ECMWF.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 600 PM CDT Tue May 9 2017
Concerns this TAF forecast period are convection and MVFR
stratus. Thunderstorms across SE Colorado and NE New Mexico at 23z
will progress slowly eastward into SW KS overnight. Followed the
latest HRRR solution closely, which depicts a loosely organized
squall line arriving on the KS/CO border around 04z, near LBL and
GCK around 06z, with remnant -SHRA near DDC through about 09z.
Gusty outflow winds to 40 kts may occur with the more organized
line segments. MVFR stratus cigs are expected at DDC, LBL and P28
during the 06-12z Wed timeframe. Kept cigs in the VFR category at
HYS and GCK. South winds near 10 kts will prevail overnight
outside of convection. After 15z Wed, SE winds of 15-25 kts
expected at all airports.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 59 78 53 67 / 40 40 50 40
GCK 57 77 51 63 / 60 50 50 50
EHA 54 75 48 63 / 60 50 30 30
LBL 56 77 50 66 / 60 50 40 30
HYS 60 78 54 63 / 20 50 70 50
P28 61 80 56 73 / 30 50 40 40
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Turner
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...Turner
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
948 PM CDT Tue May 9 2017
.UPDATE...
The previous forecast is in good shape. The only changes made
were to adjust first period hourly temperature/dewpoints and to
bump up the winds a little for tomorrow based on the latest model
runs.
&&
.AVIATION...
/ISSUED 659 PM CDT Tue May 9 2017/
Isolated showers mainly southeast of a KTPL-KF44 line will
dissipate by 03z and are not expected to affect the TAF sites.
VFR conditions are expected this evening. Expect MVFR ceilings to
spread north overnight tonight reaching KACT around 07z and the
Metroplex sites around 08z. Ceilings should lower into the IFR
category at KACT around 08z and hang in through 18z and may be in
the Metroplex during the 13z to 16z period. There will be a low
chance of showers and thunderstorms Wednesday afternoon and
evening, but the chances at the TAF sites is too to include at
this time.
58
&&
.PREV DISCUSSION... /ISSUED 343 PM CDT Tue May 9 2017/
Several days of southerly low-level winds have finally managed to
advect richer moisture across Texas, with dewpoints this hour
running in the lower 60s near the Red River, and the upper 60s to
near 70 across our southern counties. Showers and thunderstorms
have been developing across the Texas Hill Country, on the eastern
periphery of a low-level theta-e ridge amidst a region of
lingering warm advection. Thus far, convection has remained quite
tame, and is likely still feeling the effects of lingering dry and
warm air in the mid-levels based on latest RAP point soundings.
Given limited forcing for ascent (the parent upper-low is still
well off to the west and dropping into Sonora, Mexico), overall
shower/storm coverage should remain isolated to scattered this
afternoon, with the greatest coverage expected generally south of
a Lampasas to Palestine line. Any lingering activity will then
gradually fizzle this evening with the loss of daytime heating.
Given the presence of lingering dry and warm mid-level air, the
threat for any strong or severe storms remains quite low at this
juncture.
As the aformentioned upper level low pinwheels into New Mexico
this evening, additional showers and thunderstorms are expected
to develop well to our west. These will eventually congeal into an
MCS that will track towards the Texas Big Country overnight. The
current anticipation is that these storms will gradually wane as
they encounter increasing nocturnal inhibition and a veering low-
level wind field. However, it`s possible that this decaying
activity lays down an outflow boundary that may play a role in
our convective chances on Wednesday.
The upper low will finally begin to emerge across the Texas
Panhandle on Wednesday, and this added impetus will allow a
surface dryline to mix just west of our CWA during the afternoon.
The combination of this dryline and any remnant outflow from
overnight storms could serve as foci for convective development
perhaps as early as late-morning as the eastern fringes of ascent
from the low approach. Deep layer shear values approaching 40-50
kts combined with a moderately unstable atmosphere with MLCAPEs
approaching 1500 J/kg and steep mid-level lapse rates of 7.5-8.5
C/km mean storms will pose a risk for large hail and strong wind
gusts. The tornado threat appears LOW and will largely be
tempered by weaker flow in the 0-1 km layer. That said, the
presence of backed surface winds and the presence of at least
limited 0-1 km SRH suggest this potential is not zero.
Indications of lingering warm and dry air aloft near the 700
mb layer do also throw a complicating factor into the forecast
for Wednesday, as this may tend to limit storm coverage/severity.
As a result, we`ll carry 20-30% PoPs (highest along and west of
I-35/35W) given this lingering uncertainty. Storms should march
eastward, encroaching on the I-35 corridor during the mid to late
afternoon, before diminishing in coverage/intensity during the
evening as they outpace the better ascent and encounter increasing
inhibition.
We`ll continue to show low precipitation chances across our
western counties overnight Wednesday as activity may continue near
the dryline. On Thursday, latest indications are that the dryline
may actually begin to mix into our northwestern counties before
inhibition erodes sufficiently to allow the next round of storms
to fire during the afternoon. As a result, we`ve pared back PoPs
Thursday afternoon to locations east of a Comanche to Mineral
Wells to Bowie line. The thermodynamic/kinematic environment will
once again support severe thunderstorms with a large hail and
downburst wind threat as DCAPE increases past 1000 J/kg. The
propensity for surface winds to veer ahead of the approaching
dryline/cold front will once again help temper the overall tornado
threat, but we`ll need to keep an eye on any localized backing to
the flow, which simply cannot be pinpointed this far our.
Activity will come to an end for us on Thursday night as a cold
front sweeps through the region, leading to yet another nice
weekend. Southerly flow will be quick to return, however, and by
early next week, low precipitation chances will begin to return to
portions of North and Central Texas.
Carlaw
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 69 82 70 86 64 / 10 20 20 40 30
Waco 69 83 70 85 63 / 20 20 20 30 20
Paris 65 81 66 80 62 / 5 20 10 60 60
Denton 67 80 68 85 61 / 10 30 20 40 20
McKinney 66 80 68 84 62 / 10 20 10 50 40
Dallas 69 82 71 87 65 / 10 20 10 50 30
Terrell 66 81 68 84 63 / 10 20 10 60 40
Corsicana 68 84 69 84 64 / 20 20 10 50 30
Temple 69 84 69 85 64 / 20 20 20 30 20
Mineral Wells 67 80 65 87 60 / 10 30 20 20 10
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Goodland KS
516 PM MDT Tue May 9 2017
.SHORT TERM...(This afternoon through Wednesday)
Issued at 240 PM MDT Tue May 9 2017
Closed upper low is still centered near the Arizona/Mexico border
with diffluent southwest flow over the Southern Plains extending into
the Central Rockies and Central High Plains. A stalled front is
beginning to lift north as a warm front wind is now orientated just
south of Interstate 70.
This afternoon-Tonight: Shortwave trough currently rotating around
eastern periphery of closed low will continue to move over eastern
Colorado with large scale ascent and deep plume of moisture
spreading towards our CWA. Thunderstorm activity should initially be
in eastern Colorado, though I can`t rule out isolated activity along
frontal zone (hinted at by some short range guidance). Models
continue to favor increasing coverage from the west, with
propagating eastward along frontal zone (likely dependent on cold
pool development).
Deep shear is already in place with effective shear values shown by
RAP in the 40kt+ range. Instability is still building and this may
be the biggest question mark for most of our CWA due to impacts of
cloud cover. Models are showing max CAPE values in excess of 1500
J/KG by 6 PM MDT which is adequate, but trends haven`t matched up
yet. Another consideration is potential for enhanced low level shear
along frontal zone that could support tornado development
(particularly in our west), but this still seems conditional on more
discreet cells in this region (current trend is towards clusters.
Early in the event (over eastern Colorado) we may see thunderstorms
training and this could support a better chance for flash flooding.
Storm motions are generally going to be 30kt or higher, so flood
threat will be more localized and limited to early part of the event
tonight.
Wednesday: Models show a region of subsidence/dry slot shifting over
our CWA during the morning hours before large scale ascent
overspreads our CWA during the afternoon. Expect shower and
thunderstorm coverage to increase across the area through the
afternoon. Front will push back south shifting main axis of
instability with it, but we may still see a limited severe threat
with lingering elevated instability. A greater concern will be the
slow storm motions and potential for back building of thunderstorms
that could create a better threat for flash flooding than today.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 220 PM MDT Tue May 9 2017
Thunderstorms and rain will start off the extended period due to a
closed low pressure system continuing its way northeast towards the
CWA. Wednesday night will likely be the ideal time for storms to
develop as instability is the best. But, as the overnight hours
progress the instability factors start to diminish and most of the
precipitation turns to rain (with isolated lightning possible).
Thursday, the closed low shifts east before moving over the CWA and
skirts to the south of the area. This will keep most of the
instability to the south and continue rain chances over the area
(will not rule out isolated non-severe storms though). The rain is
expected to diminish through the afternoon from northwest to
southeast as the low moves southeast. By the end of the day, a ridge
is expected to move into the region from the west.
Friday through the weekend will primarily be dry due to the ridge
sitting over the CWA. By the end of the weekend southwest flow will
start to push into the region and bring moisture into the area. This
is due to a trough developing over the Pacific Northwest.
Monday will be a day to keep an eye on due to an upper level
shortwave trough looking to move through the trough and over the
region. This could potentially bring thunderstorm chances to
portions of the area (current guidance is showing along and north of
Interstate 70). Tuesday looks to dry out again with that shortwave
moving northeast of the region.
Temperatures during the period will be in the 50s/60s on Thursday due
to the region being on the back side of that trough. Friday will
increase into to the 70s. The weekend through Tuesday will be in the
80s, with Tuesday seeing some decreasing temperatures along the
northwest portion of the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 454 PM MDT Tue May 9 2017
Main issue will be the expected storms spreading east across the
forecast area this evening and overnight behind the advancing cold
front. There maybe enough elevated instability for the severe
threat to continue past 6z. KGLD would have the most prolonged
window for severe storms.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...DR
LONG TERM...CLT
AVIATION...JTL
Area Forecast Discussion
National Weather Service Indianapolis IN
1155 PM EDT Tue May 9 2017
.UPDATE...
The Aviation section has been updated below.
&&
.SYNOPSIS...
Issued at 208 PM EDT Tue May 9 2017
A weak area of Low pressure will exit Central Indiana this
evening. In its wake...a frontal boundary will be left across
Indiana...and this will be the focus for weather over the next
several days.
Mainly dry weather is expected tonight as weak high pressure
arrives in the area along with the lingering front. Much of
Wednesday should remain dry across Central Indiana...however as
the day progresses...chances for showers and storms will increase.
Daytime heating along with the arrival of an upper level
disturbance on Wednesday Night is expected to lead to more rain.
The front will continue to linger across Central Indiana through
Friday...bringing occasional showers or storms to the area
through the end of the work week.
High pressure is expected to arrive this weekend...bringing a
return of dry weather and near normal temperatures.
&&
.NEAR TERM /Today/...
Issued at 1002 PM EDT Tue May 9 2017
Going forecast in fairly good shape. Did remove remainder of pops
and thunder for the night as no signs of development noted. Made
minor adjustment to increase temp gradient overnight across the
quasistationary boundary. Will leave fog mention as patchy as HRRR
visibilities are not very aggressive at all with fog overnight, and
ongoing stratus north of the boundary may limit the fog development,
but the outside potential will remain for some dense fog near
daybreak Wednesday. Previous discussion follows.
Issued at 208 PM EDT Tue May 9 2017
Surface analysis early this afternoon shows an area of weak low
pressure over Central Illinois. A warm front extended southeast
from the low across Central Indiana. Large difference were found
on each side of the front...as seen with temps in the 50s at
Muncie and Indianapolis...and 60s and 70s on the south side at
Bloomington...Terre Haute and Vincennes. The morning showers and
storms appear to have all but ended...except for a quickly
departing showers near Greensburg and North Vernon.
Main forecast challenge tonight will be pops. GFS suggests the
surface front will remain along and near I-74. Aloft...minimal
forcing appears to prevail as ridging builds aloft. Time heights
and forecast soundings show saturated lower levels along and near
the front tonight...but with minimal forcing. Mid and upper levels
appear dry beneath the ridging aloft. Thus confidence for precip
will be low. However given the available lower level moisture
along the front and weak lower level convergence expected...some
very light rain or drizzle cannot be ruled out...but confidence
for measurable precip is low. Furthermore...fog
overnight...particularly on the north side of the front will be
expected...given the ample moisture and weak winds.
Given the expected clouds...will trend low warmer than a blend.
&&
.SHORT TERM /Wednesday through Friday/...
Issued at 208 PM EDT Tue May 9 2017
Similar features remain in place on Wednesday morning as compared
to the overnight period. Plenty of lower level moisture remains
present amid minimal forcing. Thus will expect a slow burn off of
morning clouds and fog...and again. Better forcing begins to
arrive on Wednesday afternoon as the GFS suggest a short wave
arriving in the late afternoon. Forecast soundings suggest
convective temps in the upper 70s which should be reached on the
warm side of the front...and elevated convection appears possible
near the front above the surface inversion. Thus will trend pops
upward during the late afternoon hours as more organized forcing
along with daytime heating. A blend on temps will work well.
Highest confidence for precip during this period will be Wednesday
Night as best short wave dynamics arrive aloft...riding the ridge.
With the surface front providing lower level convergence and
force soundings showing deep saturation...again...confidence is
high. Thus will trend pops higher on Wednesday night.
Again...given the expected clouds and rain will trend lows at or
above the blend.
GFS and NAM suggest more upper level dynamics poised to push
across Indiana on Thursday through Friday. The upper low over the
western plains continues to suggest short wave energy will be
ejected from the system and stream across Indiana...providing
lift. Meanwhile in the lower levels...little will have changed.
The frontal boundary looks to remain across Indiana...providing a
focus for development and lower level convergence. Thus periods of
showers and storms appear quite reasonable on Thursday through
Friday. Forecast soundings continue to suggest deep saturation
through the period with pwats ranging from 1.25 to 1.50. Although
this should not be as heavy as previous rains...the long duration
of the precip and possible isolated heavier rains could result in
additional flooding over Indiana`s already saturated grounds. Thus
through the period we will continue to trend pops highs...highs
cooler than the blend and lows warmer. As just stated...will be
watching closely the progression of these systems for flooding
threats.
&&
.LONG TERM /Friday Night through Tuesday/...
Issued at 233 PM EDT Tue May 9 2017
The blocky upper level pattern that has dominated the weather
across the lower 48 so far this month is showing no signs of
breaking...just yet. With that being said...a subtle shift in
positioning of the dual upper lows over the western and eastern
parts of the country will lead to a change in weather across the
Ohio Valley and central Indiana for the weekend trending towards
primarily dry and more seasonable for mid May.
The front responsible for the unsettled weather this week will be
departing away from the region late Friday with a surface high
pressure ridge predominantly in control for the weekend. Extended
model consensus still favoring low pressure tracking through the
Great lakes late Saturday into Sunday associated with another
piece of energy aloft diving into the eastern trough. Recent
trends have been shifting primary impacts from this feature more
north and east of the forecast area with only a small chance for a
shower Saturday night over northeast counties.
The amplifying upper low setting up over New England will help to
spin up a deep surface low off the northeast coast by early next
week. Central Indiana and the Ohio Valley will remain far enough
west for little to no impact from this system...other than
maintaining a blocky pattern that will last for much of next
week with only small chances for rain through the middle of next
week. Low level thermals are supportive of more normal
temperatures for this time of year with highs likely to be in the
70s for most throughout the extended. With cyclonic flow
present...dewpoints will be lower than average keeping humidities
low as well.
Enjoy this brief reprieve as signs do exist on the horizon for a
shift back to a more active pattern by late next week as the
western trough kicks east and the stagnant upper level pattern
begins to break down.
&&
.AVIATION /Discussion for the 10/06Z TAFs/...
Issued at 1155 PM EDT Tue May 9 2017
VFR initially will give way to MVFR at most sites and perhaps some
IFR at IND and LAF as a quasistationary front remains in the area
overnight into Wednesday.
Ample low level moisture is in place with a sharp low level
inversion expected to develop overnight north of the boundary.
Sites likely to be along and north of the boundary (IND and LAF)
will be most likely to see IFR. HUF and BMG will likely see some
brief MVFR at best.
Winds will be low confidence particularly in proximity to the
boundary, and will likely be variable at many if not most of the
sites overnight.
Conditions will show some improvement from mid morning on
tomorrow.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...Puma
NEAR TERM...Puma/NIELD
SHORT TERM...Puma
LONG TERM...Ryan
AVIATION...NIELD
Area Forecast Discussion
National Weather Service Riverton WY
330 PM MDT Tue May 9 2017
.SHORT TERM...(This evening through Friday)
Issued at 200 PM MDT Tue May 9 2017
Thunderstorms have developed early this afternoon, as expected,
from YNP into the western mountains, and are now moving off the
higher terrain to the valleys and basins to the lee of the
mountains. Brief heavy rain, small hail, and gusty wind can be
expected with the storms as they continue this afternoon, and
potentially remain through the mid evening hours. The HRRR
continues to forecast some larger stronger clusters developing off
the Washakie Needles, southern end of the Bighorn Mountains, and
central Sweetwater county, then moving ENE. Will watch those areas
for hazardous conditions if necessary. As the shortwave trough
drops southeastward over NE WY overnight, appears that an area of
showers will develop after 9pm and bring light to moderate rain
mainly to Johnson and Natrona counties, through 3 to 6am.
Anticipating some areas of patchy fog given the low and mid-level
moisture in the area, along with some clearing out by 6am as
ridging starts to develop. Then conditions should improve after
9am Wednesday as the high pressure builds to our west over Idaho.
Wednesday will thus see mostly clear skies with slightly warmer
temperatures and a north-northeast wind as the main upper level
low traverse northern NM. Thursday will see the ridge axis move
overhead, although 700mb temps only look to reach the 4 to 8C
range allowing surface temps to reach 70 to 80 across the lower
elevations. As the ridge axis moves to the WY/NE/SD border on
Friday and strengthens, western and central WY should see an
increase in southerly flow along with lightly warmer temperatures.
Some isolated thunderstorms may develop Friday afternoon over the
Tetons and northward into YNP as another large trough sets up over
the Pacific Northwest.
.LONG TERM...(Friday night through Tuesday)
Issued at 200 PM MDT Tue May 9 2017
The extended forecast starts with a strong ridge axis to our east
and a large low pressure system in the Pacific Northwest. The
initial surge of a shortwave trough with moisture appears to
mainly impact eastern Idaho into SW MT Friday into Friday night,
with a slight chance of showers and thunderstorms across far
western WY. Saturday looks to be a continuation of this pattern as
the low makes little movement to the east, although cloud cover
over western WY should decrease the temps some. The wind should
increase to 15-20 mph as well on Saturday. The main energy wave
off the trough swings SW-NE into MT on Sunday. At this time, the
model guidance does not indicate much convective activity for WY.
The resulting pattern on Sunday night into Monday though is for
some moisture to be drawn into WY from both the south and the
east, and bringing showers and thunderstorms to much of the state.
The PacNW trough then moves SE over Oregon on Tuesday, increasing
the chances for showers and thunderstorms across western WY. The
GFS and ECMWF are surprisingly in fairly decent agreement for much
of the period, so it looks likely we`ll continue with another
active weather period for the later part of the weekend into next
week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 330 PM MDT Tue May 9 2017
Scattered showers and thunderstorms will continue late this
afternoon into the evenings hours, with the storms expected to
diminish by 03-04Z Wed. The stronger storms will produce brief
heavy rain, small hail, and wind gusts of 35-40 kts. MVFR to IFR
conditions possible under and around the storms. Rain showers are
expected to develop across central WY and move southeast after 06Z
Wed, mainly impacting KCPR through 12Z Wed. Most higher terrain
across northern and central WY will be partially obscured through
15Z Wed. Several terminals will see patchy fog during the early
morning hours due to good low level moisture and some clearing skies
as high pressure starts to build in. The local fog should dissipate
after 15Z Wed, with mostly clear skies expected Wednesday at all
sites. Winds will mostly be N NE Wednesday with some stronger gusts
around KRKS up to 20 kts.
&&
.FIRE WEATHER...
Issued AT 200 PM MDT Tue May 9 2017
Weak low pressure is swinging southeastward today, along with a
large system over AZ and NM, bringing low- and mid-level moisture
and some instability to WY. Thunderstorms and showers have already
started this afternoon and are expected to continue through 8-9pm
tonight, with some of the storms producing brief heavy rain, small
hail, and gusty outflow wind. Some stronger storms may traverse
the southern Bighorn Basin, southern Johnson county, and eastern
Sweetwater county. Some rain showers are also likely overnight
over central WY before moving into SE WY. Wednesday will see
clearing skies late in the morning and afternoon, with temps
increasing over northern WY with RHs decreasing, but southern WY
will see slightly cooler temps and higher RHs due to the large low
system to the south. Thursday will be warmer and drier statewide,
relatively light wind. Friday will see warm temps and stronger
wind.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...McDonald
LONG TERM...McDonald
AVIATION...McDonald
FIRE WEATHER...McDonald
Area Forecast Discussion
National Weather Service Blacksburg VA
924 PM EDT Tue May 9 2017
.SYNOPSIS...
A warm front will continue to make very slow northeastward
progress tonight, eventually stalling overnight. The front and
weak disturbances acting on it will serve as the focus for
active weather through the rest of the workweek. Several
opportunities for showers and thunderstorms through that period,
with the wettest conditions expected on Thursday and Friday. A
return to a drier weather pattern is expected for the weekend.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 915 PM EDT Tuesday...
Multiple bands of showers and stronger thunderstorms continue to
evolve northeast across the region ahead of a stalled boundary
across the southwest this evening. Latest soundings show much of
this more of an elevated nature per multiple inversions while
aided by strong directional shear aloft. This basically over a
more stable layer heading east of the I-77 corridor where
thinking more of a heavy rain threat at least over the next few
hours. Thus have upped pops across the region given translation
of convection from southwest to northeast via bands ahead of the
boundary that should lift a bit more into the area late. Latest
HRRR suggests that coverage should finally fade a bit after
midnight as energy aloft pivots over the ridge but appears will
still be a band of showers around central zones through
daybreak. Otherwise only small tweaks to the going temps
overnight with moisture on the increase per muggy dewpoints and
PWATS over an inch off soundings this evening.
Previous discussion as of 336 PM EDT Tuesday...
Northwest to southeast oriented surface warm front continues to
bisect the forecast area, extending from southeast IN southeastward
into the NC Piedmont area. Complex mid-level pattern exists with
upper low centered over northern New England and mid-level ridge
over the mid-Mississippi Valley; gradient between the two synoptic
features implies a fast belt of mid-level northwest flow across the
central Appalachians. While earlier rain showers this morning have
dwindled, upstream regional radar shows a re-development of steadier
showers and embedded thunderstorms over northeast KY into the
Cincinnati area, with lighter showers in more stable air across
central WV.
For the rest of the afternoon/tonight: Warm front will continue
to progress very slowly northeast through overnight. How far
northeast the front ultimately makes it is still in some
question, especially with rain falling into the cool side of the
boundary. Through the afternoon and early evening, expect
ongoing rain to progress into an area roughly bounded between
I-64 and I-77. High-resolution guidance consensus suggests
ongoing thunderstorms in eastern KY may brush areas west of
I-77, but likely in a weakened state as instability is quite low
in this area, at or below 1000 J/kg MUCAPE per SPC
mesoanalysis. Later tonight and overnight, rain should be
primarily focused northeast of I-77. This should be a decent
rainfall but not thinking this would cause any significant
issues. Shown lows in the upper 40s to low 50s along the I-64
corridor, mid 50s for the central VA piedmont, Roanoke and New
River Valleys, and the mid/upper 50s for the NC Piedmont,
southern Blue Ridge and Mountain Empire region in VA.
For Wednesday: A low-confidence forecast with details heavily
contingent on the position of the warm front and on any mid-
level vorticity maxes that rotate around the mid-level ridge.
Current indications are that the warm front will have lifted far
enough northeast to allow a warm sector to extend from central
WV southeastward into northeast NC, with cooler/cloudier
conditions northeast from that line. Steep low to mid-level
lapse rates are likely in the warm sector with Showalter indices
likely in the -1 to -3C range, resulting in MUCAPES on the
order of 1500-2000 J/kg on the bullish NAM. In a capped air mass
and without any significant source of larger-scale lift, could
only go with slight to low Chance PoP wording for Wednesday
afternoon. 3-km NAM and the WRFs only depict isolated coverage
tomorrow afternoon and mainly along and south of a Blacksburg to
Danville line. Present SPC outlook for Day 2 shows General
thunder with the extreme eastern extent of the 5%
severe/Marginal Risk area extending on the VA/KY border. Cloud-
cooled upper 60s to mid 70s forecast along and north of route
460, with mid/upper 70s to low 80s in the warm sector.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 336 PM EDT Tuesday...
During this portion of the forecast, we anticipate the frontal
boundary that will have been stalled across the region to make
headway northward as a warm front. This will be in response to a
strengthening upper level ridge immediately upstream across the
Lower Ohio Valley. Not much more than twelve to eighteen hours after
this shift north of the baroclinic zone will we be watching for
another change in our overall pattern. The closed upper low/trough
that was across the Central Plains states will start arriving in the
Lower Ohio Valley by Friday. This feature will add increased jet
dynamics across the area during the day Friday, and then cross the
region Friday night.
The result of this transition will be a trend for the best coverage
of precipitation to be across the northern and eastern sections of
the region by Thursday night. This will be a shift north from the
expected scenario on Wednesday night of the precipitation bisecting
the region along a NW-SE orientation.
Friday into Friday night, the degree of coverage of precipitation
will be on the increase with the best coverage first across the
western half of the area, but spread eastward during the afternoon
and evening hours.
Please reference the HYDROLOGY section of this discussion for
details on expected rainfall and hydrologic concerns.
Temperatures during this portion of the forecast will have daily
fluctuations a little above to a little below normal for this time of
year.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 336 PM EDT Tuesday...
On Saturday, the trough axis of the upper low and associated cold
front will be heading east of the region. Lingering scattered
showers are expected during the day.
By Saturday night the upper low is expected to be over the western
Atlantic just off the New Jersey coast, centered around 38 N
latitude and progress farther eastward heading into Monday.
Concurrently, a broad upper ridge will develop from Texas to the
Dakotas. This pattern will again place our area within a northwest
flow regime. Weak disturbances within this flow may allow for some
isolated upslope showers across parts of southeast West Virginia
Sunday into Monday.
By Tuesday, the axis of the ridge is progged to have shifted east,
and be centered closer to our region. However, a shortwave trough
within the northern jetstream is expected to push through the top of
the ridge and suppress the ridge southward. Isolated convection is
expected this day, not from upslope conditions, rather from diurnal
and differential heating across the mountains.
Temperatures during this portion of the forecast will be near or
slightly below normal for the weekend, but trend to readings five to
ten degrees above normal by Tuesday.
&&
.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
As of 745 PM EDT Tuesday...
Low confidence in specifics, medium/high confidence in trends
through the TAf period.
A warm front will remain draped across the region through the
period. As is typical of a warm front dynamic forcing is vague
but there is a good amount of shear across the boundary. Expect
showers/storms through the early part of the TAF period to slide
along the front with a gradual decrease overnight. This will
allow cigs to descend and settle in at IFR with some fog
developing as well. Cigs will lift as fog dissipates Wednesday
morning. Convective cap will be present tomorrow to help
suppress convection, though something may be able to fire along
the boundary during the afternoon as heating helps erode the
cap. However, meso guidance is generally dry so will leave TAFs
dry through the latter portion of the valid period but the
situation will bear watching.
Winds will generally be light.
Extended Aviation Discussion...
A nw-se oriented frontal boundary will remain situated over or
very near the region through Saturday. Expect daily chances of
showers, and some thunderstorms. Areal coverage and timing of
thunderstorms remain low-confidence and heavily dependent on
developments further northwest.
Additional prolonged periods of sub-VFR conditions are also
forecast as upper level disturbances move along this boundary
providing for enhanced coverage and heavier precipitation. A
stronger upper low will pass over or just south of the area
Friday into Saturday. Once this system passes to the east, there
will be a trend towards improving conditions heading into the
weekend.
Confidence levels are moderate to high on the general nature of
the above discussion.
&&
.HYDROLOGY...
As of 336 PM EDT Tuesday...
Precipitation totals during the Wednesday night through Friday night
part of the forecast will be greatest across roughly that portion of
our area west of Interstate-81 and north of Route 460. By early
Saturday morning rainfall totals averaging 2.00 to 2.25 inches are
expected. The remaining portions of southwest Virginia and parts of
north central North Carolina are expected to receive amounts more on
the order of 1.33 to 2.00 inches. The Northern Mountains and
Foothills of North Carolina will receive amounts more in the range
of 0.75 to 1.33 inches.
For all of these locations, half of this precipitation is expected
to fall during the time period of Thursday through Thursday night.
As the days progress, we will monitor where rain fell, how much
fell, and how comparable it has been to the flash flood guidance as
provided by the appropriate River Forecast Centers. The Weather
Prediction Center has already posted an Excessive Rainfall Outlook
for the Thursday and Thursday night time frame for the region. The
area outline above with the expected highest totals in approximately
the same area WPC has a slight chance for excessive rain, or 5 to 10
percent chance for rainfall exceeding flash flood guidance, with a
marginal chance, or 2 to 5 percent chance of exceeding flash flood
guidance, for the remainder of the region.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AL/JH
NEAR TERM...AL/JH
SHORT TERM...DS/RAB
LONG TERM...DS
AVIATION...AL/MBS
HYDROLOGY...DS
Area Forecast Discussion
National Weather Service Tulsa OK
823 PM CDT Tue May 9 2017
...UPDATE...
.DISCUSSION...
Convection along the TX/NM border will make slow progress
east overnight. Latest HRRR output suggests activity will
be in a weakened state and may hold off until after 3-4 am
(if it makes it at all). Have tweaked/delayed PoPs some
after 06z otherwise forecast is in good shape.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 67 82 64 79 / 30 40 40 60
FSM 66 86 66 81 / 10 20 40 60
MLC 65 80 65 81 / 10 30 30 50
BVO 63 81 62 78 / 30 40 40 60
FYV 62 81 63 76 / 10 20 40 70
BYV 63 83 63 76 / 10 30 40 70
MKO 64 81 64 79 / 20 40 40 60
MIO 63 81 63 78 / 30 40 40 60
F10 65 79 64 80 / 20 40 40 50
HHW 65 80 66 80 / 10 20 20 60
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
SHORT TERM...18
LONG TERM....99