Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/18/17
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
719 PM MDT Thu Aug 17 2017
.UPDATE...
Quick update to lower PoPs and remove severe wording for the
remainder of the night. Storms have already moved into Texas or
dissipated, and not expecting much redevelopment. However, the HRRR
continues to show some new developmenet around 06Z across Quay and
Curry counties, so have left the majority of PoPs in this area.
Updates already out.
34
&&
.PREV DISCUSSION...523 PM MDT Thu Aug 17 2017...
.AVIATION...
00Z TAF CYCLE
A few showers and thunderstorms continue across the eastern plains of
NM early this evening, but these should decrease through sunset. It
appears the window for severe weather is closing quickly, with the
best chances now east of the NM/TX border. VFR conditions should
prevail overnight, though it is not out of the question that MVFR or
IFR cigs creep across the border and over KCAO between 09Z and 13Z or
so. Friday`s convection should also be isolated, favoring the south
central mountains and portions of the east central plains.
34
&&
.PREV DISCUSSION...333 PM MDT Thu Aug 17 2017...
.SYNOPSIS...
Scattered showers and thunderstorms are expected to persist this
afternoon and into the evening along and east of the Central Mountain
Chain. Some storms in northeastern New Mexico may be strong to severe
this afternoon and evening. On Friday, storm coverage will again be
limited to the Eastern Plains with a few strong storms possible.
Elsewhere on Friday, expect partly cloudy skies with above normal
temperatures. A pattern shift starting on Saturday will bring a
monsoon burst back to New Mexico with wetter conditions expected
through next week.
&&
.DISCUSSION...
The next 36 hours will be the last quasi-dry period through the
remainder of the forecast period as the pattern shifts with a
monsoonal burst developing on Saturday.
Currently the area is situated on the west side of the broad west-
east oriented ridge centered over the northeastern Gulf Coast. A
broad trough is in place over most of the northern CONUS with a low
centered over the Great Lakes this afternoon. There is a shortwave
over eastern CO that is moving through the western half of the
trough with a upper jet located over the Southern Plains from CO into
the Upper Mississippi Valley. This places the northeastern portions
of the state in the right-rear jet entrance of the jet with the weak
synoptic support. Dew points are currently into low 60`s into Union
county with a weak dryline apparent in surface observations over
southeastern NM. CAPE values range from about 3000 J/kg (MLCAPE) to
over 4000 J/kg (MUCAPE). So, with all that said, SPC has a there is
a slight risk over severe weather over extreme NE NM and over the
Texas Panhandle. Cells are expected to be the strongest near the
NM/TX border with the main threat tonight being large hail and strong
winds.
Friday looks to be fairly dry again over most of the forecast area
with above normal temperatures west of the Central Mountains and
scattered showers and thunderstorms over the Eastern Plains in the
afternoon. Dynamics on Friday don`t look as favorable for more than
some isolated strong thunderstorms.
Saturday begins the pattern shift into a monsoonal burst as the ridge
shifts eastward and the trough begins to develop over CA/AZ. This
will place most of the state in a fairly broad southerly flow over
the Land of Enchantment with moisture entering the state from both
the Gulf of Mexico and from the Eastern Pacific. The GFS has PW
values surging up to about 1.5" over SE NM and just over an inch here
in the ABQ Metro Area by Monday. This pattern will generally hold
through the week, helping to fire off showers and thunderstorms over
most of the forecast area through the remainder of next week.
54/Fontenot
&&
.FIRE WEATHER...
A trough is digging southward along the CA coast and will remain
within this proximity for the next few days. Farther east, high
pressure has been anchored over the Gulf Coast, but this will reach
farther west into NM over the next couple of days. Dry air, by mid
August standards, remains in place over western and central NM with
better boundary layer moisture having seeped into the far eastern
plains. This is fueling the development of isolated to scattered
storms this afternoon, and as updrafts become more organized a few
strong to severe storms will be possible. Humidity values are lowest
in the western to central zones where readings have dipped to 15 to
25 percent while Haines indices have climbed to a value of 5 in much
of this area. Storms will largely diminish this evening with perhaps
a stray cell or two surviving after midnight in eastern NM. Similar
to last night, humidity recoveries will be fair (40-60 percent) in
western and central zones with excellent recoveries in the far
eastern tier of the plains of NM.
On Friday, higher dewpoints will be concentrated over the east
central to southeastern parts of NM where a dryline will separate
much drier air to the west and north. This will give a sufficient
trigger for isolated to scattered storms again along and east of the
dryline Friday afternoon, but most of this activity would fall just
south of the Albuquerque fire weather forecast area. Otherwise,
light winds will prevail with high pressure established more
directly over NM, and temperature and humidity trends will not
differ much from today.
A western centroid of high pressure aloft will stay atop of NM
Saturday while the trough/low aloft remains off the CA coast.
Surface winds will begin turning more southerly in direction, and
this will slowly, but steadily, steer subtropical moisture into
southern and eventually central to northern parts of the state.
Wetting precipitation chances will slowly start to increase
Saturday, but into Sunday high pressure will weaken over NM. This
will set up a better squeeze play with deeper subtropical moisture
advecting northward into NM, and the monsoonal burst will increase
probabilities for wetting storms Sunday through Tuesday. Haines
indices would lower and humidity would trend upward substantially.
Temperatures will be seasonal on Saturday, but will fall just below
normal Sunday and Monday as precipitation increases.
Storms remain in the forecast for all zones the latter half of next
week, but some uncertainties exist on the exact placement of upper
level features and the details that will follow. Moisture looks
sufficiently available for recycling and daily rounds of storms at
this point.
52
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Bismarck ND
906 PM CDT Thu Aug 17 2017
.UPDATE...
Issued at 856 PM CDT Thu Aug 17 2017
Convection has notably increased in intensity over the past hour
across northwest North Dakota as of 02 UTC ahead of the shortwave
across far northeast Montana and into Saskatchewan. This increase
may be tied to locally enhanced deep layer shear ahead of the
wave which is suggested by the 01 UTC RAP analysis. The 00 UTC
HRRR, 22 UTC ESRL HRRR and 01 UTC RAP suggest convection may
become more numerous across the north central and through the
James River Valley through the night as the aforementioned wave
propagates southeast into a more moisture rich environment,
characterized by surface dewpoints in the 60s. Deep layer shear is
also at least marginally supportive of organized convection which
is confirmed by the updraft helicity signatures from the HRRRs.
Thus, cannot rule a few more elevated severe storms through the
night. The primary threats will be quarter to half-dollar size
hail, damaging winds to 60 mph and dangerous lightning.
UPDATE Issued at 645 PM CDT Thu Aug 17 2017
Isolated to scattered high based convection continues across
western into north central North Dakota with a few mid level
impulses ahead of the more boarder wave across northeast Montana
into Saskatchewan as of 2345 UTC. MLCAPE around 1000 j/kg and weak
deep layer shear suggests that the severe threat is rather low.
However, gusts of 30-40kts are possible with the stronger storms
given their high based nature. The CAMs through the 22 UTC HRRR
suggest at least isolated to scattered elevated convection will
propagate east and maintain itself through the night aided by the
aforementioned wave. However, a large spread in the CAMs remains,
with the HRRR the most aggressive in strengthening convection
overnight across central North Dakota. This is certainly not out
of the question, but still somewhat uncertain.
&&
.SHORT TERM...(This evening through Friday)
Issued at 156 PM CDT Thu Aug 17 2017
Fire weather concerns and Thunderstorm chances highlight the short
term forecast.
Currently, low pressure was situated near Watford City along a
trough situated from Saskatchewan through the western Dakotas.
Over far western ND and eastern MT, dewpoints have dropped behind
the surface trough with some gustier winds. However, a shortwave
tracking across Montana is bringing an area of increased
cloudiness into southwest ND at this time, and should may help
temper afternoon highs, which would inhibit fire weather potential
somewhat.
Tonight, mesoscale models are hinting at two areas of showers and
thunderstorms. the first is associated with the aforementioned
shortwave trough and tracks west to east along the ND/SD border,
extending south through SD. The strongest convection remains
mostly to the south of ND.
A second area of convection tracks across northwest and north
central ND, and then southeast into eastern ND during the
overnight hours. Severe thunderstorm appears on the minimal side,
but with around 1000 J/KG of CAPE and 25 to 35 knots of shear this
evening, an isolated severe storm can not be ruled out. Some of
the mesoscale models have indicated some weak to moderate updraft
helicity signatures dropping southeast from Canada this evening.
Warm and dry on Friday. We lowered the dewpoints from guidance in
the southwest Friday afternoon, but winds do not appear to be very
strong.
.LONG TERM...(Friday night through Thursday)
Issued at 156 PM CDT Thu Aug 17 2017
he extended forecast begins Friday night with a shortwave ridge
bringing warmer temperatures Friday and especially Saturday.
Highs should be in the 80s Friday with more widespread lower 90s
by Saturday. This will be followed by a Pacific cold frontal
passage cooling the region back into the 70s and lower 80s Sunday
through Tuesday. This will also bring a chance for scattered
showers and thunderstorms Sunday and Sunday night. Broad ridging
develops aloft by early to middle of next week suppressing
convection and returning warmer temperatures to the region.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 856 PM CDT Thu Aug 17 2017
Scattered thunderstorms this evening across northwest and far
north central North Dakota will move east through the night
across much of the central and into the eastern portions of the
state, possibly becoming more numerous. A few storms may be severe
with large hail and damaging winds. A few showers and
thunderstorms may linger through the morning across the James
River Valley. Otherwise, VFR conditions are expected outside of
precipitation for the 00 UTC TAF cycle.
&&
.FIRE WEATHER...
Issued at 156 PM CDT Thu Aug 17 2017
While there are some fire weather concerns today critical fire
weather conditions are not expected.
A warm thermal ridge will support high temperatures today around
90 southwest into west central North Dakota. While consensus
models show Minimum RH values around 20 percent opted to use the
dryer HRRR model which supports Minimum RH`s as low as 15 percent,
and also extended the lower humidities a little farther east. A
wind shift to the Northwest is forecast with the surface trough
passage late this afternoon. Again, raised winds a tad over
consensus to around 15 mph with gusts 20 to 25. Based in this
there should not be sufficient winds to create critical fire
weather conditions today.
Another warm day is forecast Saturday with a more significant
frontal passage late Saturday afternoon and night. We utilized a
blend of higher wind guidance over our given guidance. BUFKIT
forecast NAM/GFS soundings for Saturday afternoon support
sustained winds of 15 to 20 mph and gusts of 25 to 30 mph. This
period will certainly need to be monitored for possible critical
fire weather.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...PA
SHORT TERM...TWH
LONG TERM...TWH
AVIATION...PA
FIRE WEATHER...TWH
Area Forecast Discussion
National Weather Service State College PA
1156 PM EDT Thu Aug 17 2017
.SYNOPSIS...
A cold front will move through the region Friday triggering
showers and thunderstorms. The cooler air will be replaced by
warmer air Monday into Tuesday as a ridge builds aloft. Another
cold front should trigger showers around mid-week and the week
should end on a cooler note.
&&
.NEAR TERM /UNTIL 7 AM FRIDAY MORNING/...
There were a few thunderstorms were over south-central
Pennsylvania at 930 PM. Some showers were present over northern
and northwestern Pennsylvania.
The HRRR pushes the area of shower to the west through the
region by 4 AM. Rainfall amounts are generally light. Some hints
in northwestern PA of some potentially stronger cells with
rainfall potential of an inch in these stronger cells, should
they develop.
Many areas, especially in the southeast should remain rainfree
overnight though patch fog is possible.
&&
.SHORT TERM /7 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
The HRRR goes to about 17Z and it shows a weak line of showers
and thunderstorms across our southwestern counties northeast
toward Tioga county. General concept is showers developing
around 15-17Z Friday.
The HRRR shows CAPE over 2400JKG-1 east of these showers and
other NCEP models show over 1800JKG-1 of CAPE to the east. Thus
have higher POPS in central to southeastern PA in the afternoon
hours.
Models indicated the potential for some strong to severe
thunderstorms Friday afternoon and the potential for some
locally heavy rainfall. Most models show mainly 0.25 to 1.00
inch of QPF but stronger cells could produce higher amounts.
Most guidance shows the cooler drier air improving conditions in
western PA in the late morning and early afternoon. The front
should clear our southeastern counties in the 22Z to 03Z
timeframe Friday evening.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Models imply a weak wave could trigger some light showers on
Saturday evening. Sunday into Tuesday looks very dry. The next
chance for widespread rain would likely be around Wednesday and
possibly into Thursday as short-wave and cold front move into
the region.
At this time Wednesday has the higher probability of QPF then it
dries out Thursday into Friday. The PW forecasts show low PW
over the region Saturday to Tuesday then a surge of higher PW
air Wednesday ahead of the front. Then the PW falls Thursday
into Friday to below normal values.
Temperature wise, the cool air should be replaced by warmer air
by Monday afternoon and Tuesday should be even warmer still. The
850 hPa temperatures go above normal Monday evening and peak in
the 16-19C range Tuesday afternoon. Tuesday could be quite hot.
Good news is the 850 hPa temperatures fall Wednesday into
Friday. Most guidance shows below normal 850 hPa temperatures by
Friday with below normal PW values. The week as currently
forecast should end on a cool dry note (like D sharp?).
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
A weakening band of showers and a few thunderstorms is pushing
into central Pa late this evening. A brief vis reduction remains
possible at KBFD/KUNV/KAOO through around midnight.
Focus late tonight will shift to the possibility of low cigs at
KBFD, as moist southerly flow and orographic lift combine to
produce developing stratus across the high terrain of northern
Pa. Latest model soundings, MOS guidance and SREF probability
charts all point toward likely IFR cigs at KBFD late tonight
into Friday morning. Elsewhere, MVFR cigs are a possibility late
tonight, although southerly flow at KJST is climatologically
unfavorable for cig reductions.
Expect increasing cig heights by late morning, as mixing occurs
ahead of approaching cold front. Latest SREF prob charts support
predominantly VFR conditions everywhere by early afternoon.
However, scattered showers/storms developing along cold front
could produce brief vis reductions and gusty winds at a few
locations across eastern Pa during the afternoon.
.OUTLOOK...
Sat-Mon...No sig wx.
Tue...SHRA/TSRA poss.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Grumm
NEAR TERM...Grumm
SHORT TERM...Grumm
LONG TERM...Grumm/Lambert
AVIATION...Grumm/Fitzgerald
Area Forecast Discussion
National Weather Service Wilmington OH
756 PM EDT Thu Aug 17 2017
.SYNOPSIS...
A cold front will move through the region late in the overnight
and into the morning on Friday. High pressure will then briefly
move into the region, however another disturbance is expected
to bring additional precipitation chances to the region for
Saturday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A round of much less organized thunderstorm activity will push
in to southern CWA from the southwest this evening and slowly
move east tonight. Increased the chances of storms here and
lowered significantly elsewhere behind the earlier line of
storms. Temperatures were adjusted for a few hours this evening
given the cooler post-thunderstorm atmosphere for the I-71
corridor, but are expected to rebound to be fairly uniform with
overnight lows in the upper 60s to around 70. The threat for
this second round of storms to produce any damage is minimal but
will be monitored through the evening.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Dry conditions are expected for much of Friday and into Friday
night. A quick moving upper level disturbance will approach the
region late in the overnight Friday night and therefore
introduced some precipitation chances across northwestern
portions of the area. Went close to conshort and superblend for
temperatures during this time.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Period begins with a H5 s/w swinging through the srn Great Lakes.
Extended models still are showing a range in their QPF forecasts.
The NAM is the driest, with very little QPF produced while the
Canadian hemispheric carries the most. Will continue with a
north/south gradient in the PoPs, going from 30 in the north to 10
in nrn KY. Highs will be seasonal ranging from 80 to 85
degrees.
The s/w pulls away Saturday night, allowing high pressure to build
in at the surface. The high will keep the region dry Sunday into
Monday. By Tuesday, models drop energy into the region from the
Great Lakes, bringing scattered thunderstorms. Cold front will drop
through the region Tuesday night lowering pcpn chances from n to s.
There are timing differences so kept PoPs across the entire fa
Tuesday night.
Front will gradually pull away from the from region on
Wednesday, bringing an end to the pcpn threat.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
A second round of showers and thunderstorms will affect southern
TAF sites early this evening, but should only hit KILN with
non-thunderstorm showers and miss CVG/LUK with convective
activity staying to their south/east. HRRR shows this area
affecting the region east of the I-71 corridor and not reaching
CMH/LCK whereas the other models seem unrealistic by painting a
broad swath of storms along and even west of the corridor. These
missed the initial line of storms and are being discounted as
viable solutions.
Outside of shower activity, VFR conditions should prevail for
the overnight and into tomorrow. Some cu topped with AS or CI
from upstream storms will dissipate later this evening and some
patchy fog could develop and reduce vsbys to 5sm in spots after
midnight through daybreak.
OUTLOOK...Thunderstorms are possible on Saturday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Novak
NEAR TERM...Franks
SHORT TERM...Novak
LONG TERM...Sites
AVIATION...Franks
Area Forecast Discussion
National Weather Service Marquette MI
801 PM EDT Thu Aug 17 2017
.SHORT TERM...(This evening through Friday)
Issued at 332 PM EDT THU AUG 17 2017
Latest 19z WV imagery and RAP analysis indicated a vigorous
mid/upper level low over far NW WI fast approaching western Upper
Mi. Radar imagery shows increasing shower coverage as forcing
ahead of the mid-upper low combines with MLCAPE values 500-1000
j/kg highest over Menominee County. Instability has also led to
a few isolated t-storms.
Into this evening, radar trends and short range high res models
suggest showers continuing into the evening hours along
with some isolated t-storms into early evening. The main threat
will be for heavy rainfall of several inches with any stronger
slow moving shra/tsra clusters as PWAT values climb into the
1.50-2.00 inch range. Even though effective shear will be weak
(generally 25 knots or less), with the strong vorticity center
moving into the area combined with modest instability there may
be a slight potential for a brief/weak funnel/tornado similar to
what occurred over srn MN yesterday afternoon and evening.
Tonight, as the mid level low lifts to the northeast, the heavier
shra/tsra will diminish by late evening. Additional lighter wrap-
around rain/drizzle will develop over the northwest half especially
where upslope nnw flow/lift is strongest.
Friday, Some isolated showers could linger into the morning hours
especially for nw upslope locations but then as low continues to
lift ne expect drying and partial clearing from the west in the
afternoon. NW winds will remain fairly gusty through much of the
day especially north central and east where gusts of 25-30 mph can
be expected. These blustery winds will lead to large waves and a high
swim risk for the Lake Superior beaches of Marquette and Alger
counties on Fri. However, it won`t be a day to go to the beach due
to clouds/shra and temps struggling to get out of the lower 60s over
the n central and ne fcst area where shra/cloud cover will be most
persistent. Farther west and for downsloping locations south central
in nw flow, high temps Fri could reach into the lower 70s with the
possibility of afternoon breaks in cloud cover.
.LONG TERM...(Friday night through Thursday)
Issued at 332 PM EDT THU AUG 17 2017
Saturday and Sunday: As the upper-level trough and surface low
continue to shift eastward, weak upper level ridging and a suface
high pressure system are expected to build across the Upper Great
Lakes Region for Saturday into Sunday morning. This will allow winds
to diminish across the area and allow skies to become clear to
partly cloudy through Sunday morning. There may be a few afternoon
showers that develop over the eastern U.P. on any lake breezes that
develop; however, the coverage should remain isolated for the day
Saturday. Sunday afternoon a weak surface trough is expected to
slide in from the west, which will bring scattered showers and
thunderstorms from west to east across much of the U.P. through the
evening hours. Sunday afternoon will be very warm ahead of the
surface trough with many locations warming into the mid 80s.
Monday into Tuesday: The next area of broader troughing will shift
eastward toward the Upper Great Lakes for this time period. As this
happens, a cold front is expected to shift into the area Monday
afternoon and then slowly shift eastward into Tuesday afternoon. As
moisture, forcing and instability increase along and ahead of the
front, expect showers, thunderstorms and cloud cover to increase
across the area Monday afternoon through Tuesday.
Rest of the extended: The front will be east of the area on
Wednesday allowing condtions to dry out a bit; however, the upper
level trough axis nearby along with the potential for a shortwave
passing through will allow for at least increased afternoon cloud
cover and possibly some diuranl afternoon rain showers. Temperatures
will be near normal for this time period. At this point, will stick
with a consensus of the models for this time period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 800 PM EDT THU AUG 17 2017
Upslope, moist flow on the back side of a surface low pressure
system currently near KSAW will promote low CIGs, rain and reduced
VIS at all sites into Friday morning. Gradual improvement from W to
E will be noted on Fri as the low exits the region.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 332 PM EDT THU AUG 17 2017
Easterly winds could briefly gust to low end gales to 35 knots over
far eastern Lake Superior into late this afternoon. The winds will
become NW on Friday as the low departs to the east, with 20-30 knots
expected for the east half. Lighter winds, mostly under 20 knots,
are expected over the weekend into early next week with high
pressure over the region.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...KEC
AVIATION...Titus
MARINE...Voss
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
850 PM CDT Thu Aug 17 2017
.UPDATE...
Increased rain chances slightly tonight mainly in northwestern
Oklahoma. Added patchy fog mention late tonight into Friday
morning east of a Marietta to Pauls Valley to Purcell to
Stillwater line.
&&
.DISCUSSION...
Some thunderstorms may impact northwestern and northern Oklahoma
after 10 pm tonight. Fog may form across parts of central,
southern, and southeastern Oklahoma late tonight into Friday
morning.
Latest radars indicated scattered strong to severe thunderstorms
across the Panhandles near Guymon, Oklahoma south to Stinnett,
Texas as of 845 pm CDT. These storms were moving eastward. Think
this activity will move into northwestern Oklahoma towards Gage
and Woodward 10 pm to midnight, though may weaken as the storms
encounter a more stable airmass with higher amounts of CIN.
Regardless, brief gusty winds, probably sub-severe winds mainly
under 50 mph, small hail, along with heavy downpours could impact
northwestern Oklahoma later tonight.
After midnight tonight, not sure if storms will continue as they
move farther east and southeast due to stronger capping and
higher amounts of CIN. However, a low level jet will bring a
slight increase in moisture and instability to the area, which may
maintain some storms mainly over the northern half of Oklahoma. A
low level cold pool may be deep enough to help sustain
convection. If storms occur, severe potential remains low due to
MUCAPE values generally under 2000 J/kg and 0-6 km shear generally
below 30 kt (closer to 20 kt). Kept rain chances generally 20-40%
anywhere north of a Crowell, Texas to Ada line with the highest
chances northwest of a Hollis to Weatherford to Ponca City line.
Added fog mention to some locations mainly east of I-35 and
southeast of I-44 based on latest HRRR runs and as there will be
an increase in low level dewpoints (rising into the mid 70s) which
would allow for supersaturation near the ground. Doubt this fog
will become too dense due to the lack of rainfall during the day
today and as ground temperatures are rather warm (generally in
the lower to mid 80s). Regardless, visiblities may be under 1 mile
in some locations near Durant, Atoka, Ada, Ardmore, Seminole,
Shawnee, and Chandler between 1 am tonight and 10 am Friday
morning.
Products will be updated shortly.
MBS
&&
.PREV DISCUSSION... /issued 637 PM CDT Thu Aug 17 2017/
AVIATION...
18/00Z TAFs. VFR conditions will be forecast through period
outside of potential restrictions with TSRA in the 6-12Z timeframe
across northern Oklahoma terminals. Additional TSRA possible late
tomorrow but confidence too low for placement attm.
PREV DISCUSSION... /issued 338 PM CDT Thu Aug 17 2017/
DISCUSSION...
Subsidence behind eastward moving shortwave trough over the Great
Lakes and in the wake of MCS has resulted in mostly clear skies
across the area this afternoon. Some diurnal cumulus development
has been noted where low level moisture remains highest, mainly
across south-central and southeast Oklahoma. More extensive
vertical growth of cumulus and convective development should be
confined to just south of our forecast area.
Strengthening moist southerly flow over the High Plains should
support some diurnal surface based convective development later
today where 0-2 km stream lines are slightly convergent and near
the Raton Mesa. This would then move eastward with mean flow and
possibly grow up scale slightly potentially reaching our northwest
counties late this evening and progressing eastward in a weakened
state overnight. Models show a thin layer of enhanced mid-level
moisture on the 315k surface. Models can sometimes struggle with
depicting the details of moisture in these scenarios and this is
the main source of uncertainty in the overnight forecast. If mid-
level moisture is as extensive or more extensive than short term
guidance suggests, this would contribute to at least weak MUCAPE
and support elevated convection through tomorrow morning,
primarily over the northern half of the forecast area.
Current thinking is that overnight and early morning convection
shouldn`t be as deleterious to later afternoon potential as some
of the recent more intense MCSs. Later in the afternoon, moderate
to strong instability should develop near a weak cold front across
northwest Oklahoma. Mid-level height rises may work against
convective development, but given the degree of diabatic
heating/destabilization, isolated to scattered thunderstorm should
form within this zone of convergence. Deep layer shear should be
marginally supportive of storm organization and some wind/hail
potential. Some consolidation and increase in coverage may occur
through late evening as storms move eastward potentially lasting
into the night.
A drier pattern should develop this weekend into next week as mean
ridging builds slightly. We`ll need to watch boundary layer
moisture characteristics. If models are under forecasting low
level moisture slightly, isolated diurnal convective development
may become more likely. Otherwise, there may be a period of weak
synoptic scale forcing to aid in convective development late
Tuesday and Tuesday night.
BRB
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 70 91 73 94 / 20 30 40 10
Hobart OK 72 95 74 96 / 30 20 30 10
Wichita Falls TX 73 94 74 96 / 10 10 20 10
Gage OK 68 93 69 94 / 40 40 40 10
Ponca City OK 69 91 70 92 / 30 30 40 10
Durant OK 73 92 74 95 / 10 20 30 20
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
17/11
Area Forecast Discussion
National Weather Service Pueblo CO
232 PM MDT Thu Aug 17 2017
.SHORT TERM...(This evening through Friday)
Issued at 231 PM MDT Thu Aug 17 2017
This evening, a weather disturbance will be moving acrs western NE
and also affecting portions of eastern CO. A limited amount of
showers/tstms are expected this evening, with the majority of the
activity expected to be over the central and eastern mountains, and
over the southeast plains. It still looks like the most favorable
area for potential severe weather will be over the far southeast
plains. The current meso analysis indicates 2000+ J/kg of CAPE over
the far southeast plains, and deep layer shear values of around
40kts. Much of the convective activity is forecast to be done by 02-
03Z, but both the NAM and the HRRR show lingering pcpn into the late
night hours over the far southeast corner, so I will keep some isold
pops in that location past midnight.
Behind that weather disturbance, a front is expected to move into
southeast CO Fri morning bringing northerly winds, that then become
easterly in the afternoon. The forecast models show very limited
amount of convection, with maybe just some isold showers/tstms
developing over the mtns. High temps on Fri should be around
average.
.LONG TERM...(Friday night through Thursday)
Issued at 231 PM MDT Thu Aug 17 2017
Friday night`s weather should remain benign over much of the region,
with the GFS20 hinting at a few mountain showers during the early
and later afternoon hours. The NAM also hints at mountain storms, as
well, but not nearly as widespread as the GFS20. The plains should
remain clear form any convection Friday evening, low dew points
temperatures accompanied with a solid cap will inhibit any storms
from developing.
A lee trough will develop over the region on Saturday. That lee
trough will interact with a CAPE values ranging from 1000 - 1500
J/kg over the far eastern plains. The thunderstorms will be likely
be short-lived due to the lack of shear in the atmosphere. Potential
risks include strong thunderstorm winds and small hail. The NAM12
and GFS20 also indicate some weak thunderstorms developing over the
Palmer Divide, Eastern San Juans, and the southern Wet Mountains.
There will be much less energy and shear in the atmosphere over
these regions, so the storm that develop will be short-lived and
weak.
Sunday - Thursday
The monsoonal moisture surge will return on Sunday, and the biggest
forecast question is where the location of the upper-low and upper-
ridge will set-up. The European model has the upper-low set-up over
north-central Utah and the ridge built more westerly, over Colorado,
whereas the GFS pinpoints the upper-level low off the coast of
California and the upper-level ridge over the central United States.
Nevertheless, the response will be daily thunderstorms initiating in
the early afternoon over the mountains and spreading over the plains
during the late afternoon to early evening hours, but the
uncertainly lies on where the low-level moisture will settle. Over
late Monday evening and early Tuesday morning, a weak cold front
will propagate over the region, bringing the possibility for
prolonged showers during the overnight hours. Post frontal moist
upslope flow will likely bring widespread cloud cover over most of
the region, so expect a few overcast days following Monday. The long
term GFS20 resolves a lee cyclone developing over northern Colorado
on Wednesday night and Thursday morning, and if that verifies,
expect wide spread precipitation as the low and its associated
fronts, pass the area.
-Skelly
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 231 PM MDT Thu Aug 17 2017
VFR conditions are expected at KCOS, KPUB and KALS through the next
24 hrs. This evening there will be the possibility of showers/tstms
at or near KCOS, and there is a small chance that showers/tstms
could move into the KPUB and KALS areas. Precipitation chances
near the terminal forecast sites should mostly end by 02-03Z. On Fri
there may be some precipitation over some of the mtn areas, but at
this time it looks like they should not affect the terminal forecast
sites.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...28
LONG TERM...SKELLY
AVIATION...28