Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/29/18
Area Forecast Discussion
National Weather Service Bismarck ND
1010 PM CDT Thu Jun 28 2018
.UPDATE...
Issued at 1010 PM CDT Thu Jun 28 2018
Based on recent radar trends and evening CAM simulations,
confidence remains high that a widespread wind threat will cross
western and central ND over roughly the next six hours. As the
cold-pool-driven forward propagation takes hold and the the speed
at which the line moves eastward averages 60+ mph, the threat may
rapidly spread eastward faster than even recent HRRR simulations
would suggest. Accordingly, collaboration is taking place with SPC
and a Severe Thunderstorm Watch will likely be issued before 04
UTC to replace the current Tornado Watch and which would likely
extend eastward across most of the state.
UPDATE Issued at 840 PM CDT Thu Jun 28 2018
Quick update to add Wells county to the Flash Flood Watch per
radar trends through 0145 UTC, with additional rounds of
convection expected through the night.
&&
.MESOSCALE DISCUSSION...
Issued at 805 PM CDT Thu Jun 28 2018
A significant severe weather outbreak is unfolding across western
and central ND. Through 03 UTC, the greatest threat to include
potentially very large hail to around baseball size and possibly
tornadoes will accompany the supercells evolving from Dunn County
eastward across Mercer, McLean, Sheridan and Wells Counties. A
large convective cluster with potentially widespread damaging
winds will then likely enter western ND beginning between 02 and
03 UTC and will rapidly race eastward overnight.
The 00 UTC Bismarck sounding showed weak residual capping centered
near 760 mb, though at the time of the balloon launch low-level
moisture had mixed out slightly on a local basis, and modifying it
for dewpoints above 70 F suggests MLCIN is essentially minimized.
Surface analyses show the warm frontal boundary -- while loosely
defined -- extending from southern McKenzie County eastward toward
Beulah and Harvey. Ascent associated with a leading impulse aloft
has likely aided convective initiation and the environment along
the warm frontal zone is characterized by strong deep-layer shear
with effective bulk wind differences on the order of 60 kt and
MLCAPE ranging from 4500 J/kg on the Dunn/Mercer County segment
of the frontal zone to 3000 J/kg in the Sheridan/Wells County part
of the front, per the 00 UTC RAP-based objective analysis run at
SPC. This is supporting an environment which is highly favorable
for significant hail production. Objective analyses also support
0-1-km SRH in the 100-200 m2/s2 range in support of fixed-layer
significant tornado parameter values around 4 along and about 50
miles either side of the warm frontal zone. The hodograph from the
00 UTC Bismarck RAOB displayed a distinct concavity in the 1 to 3
km layer, which model simulations have consistently advertised and
which may be limiting low-level mesocyclone intensity thus far. We
expect low-level hodographs to enlarge with concurrent increases
in SRH and reductions in the current concavity by about 02 UTC,
which may support an increase in tornado potential in the next 60
to 90 minutes if discrete storm modes can be maintained.
Otherwise, upscale growth is ongoing with convection in eastern MT
in association with more well-defined height falls aloft. Clusters
of storms are relatively closely spaced and in time are organizing
in a more linear fashion, which is expected to generate expanding
cold pools the next few hours, which should eventually support a
forward-propagating MCS. Strong westerly flow aloft atop stout
low-level east-southeast flow will support downshear-propagating
meso-beta element (Corfidi) vectors on the order of 60-70 kt and
thus once the cold-pool-driven propagation takes hold the MCS is
expected to rapidly move across western ND between roughly 02 and
05 UTC, and central ND between 05 and 09 UTC. Given the degree of
bouyancy and strong wind fields, significant-severe-caliber winds
of 80 mph are likely with bowing segments of the line tonight, and
widespread damaging winds remain a considerable concern.
&&
.SHORT TERM...(This evening through Friday)
Issued at 412 PM CDT Thu Jun 28 2018
Very active late afternoon and night with significant severe
weather expected. Tornado watch was issued during the hour for all
but the northern tier counties along the Canadian border. The
tornado watch is in effect until 11 pm CDT, but it is important to
note that additional watches will likely be needed for this
event, which will last through much of the night. In addition, a
flash flood watch is in effect for west central through north
central counties. Please see previous discussion that covered the
factors supporting the flash flood threat.
Otherwise, SPC meso page continues to show extreme CAPE in excess
of 5000 J/KG across the southwest, decreasing northward.
Convective development has been hindered much of this afternoon
with lack of large scale forcing, which should change as upper
level support increases with approaching upper level trough. CAM
solutions continue to struggle with convection, but all trend
toward a better organized convective system moving in from Montana
this evening.
Friday SPC day 2 outlook continues to show general thunderstorms
for ND, however latest SREF guidance appears to be pointing toward
the possibility of some stronger storms.
.LONG TERM...(Friday night through Thursday)
Issued at 412 PM CDT Thu Jun 28 2018
Upper level trough continues moving across the Northern Plains
supporting continued thunderstorm chances through the weekend
under cyclonic flow. High temps cool down into the 70s before
rebounding again into the 80s early next week. Near zonal flow
with occasional impulses working through the flow will support a
continue active pattern with chances of showers/thunderstorms.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 840 PM CDT Thu Jun 28 2018
As of 0145 UTC, severe thunderstorms have thus far avoided the
TAF sites across western and central North Dakota. However, a
significant line of severe thunderstorms across eastern Montana
will track across western and central North Dakota tonight.
Damaging winds in excess of 65kts, large hail, and LIFR conditions
are expected. TAFs will be updated based on radar trends.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 7 AM CDT /6 AM MDT/ Friday for
NDZ001>005-009>013-017>019-021>023-031-032.
&&
$$
UPDATE...CJS
MESOSCALE...CJS
SHORT TERM...JNS
LONG TERM...JNS
AVIATION...PA
Area Forecast Discussion
National Weather Service Columbia SC
1010 PM EDT Thu Jun 28 2018
.SYNOPSIS...
There will be lingering surface troughing across the area
through the weekend. This feature plus strong heating will help
support scattered mainly afternoon and evening thunderstorms.
It will be hot with peak afternoon heat index values around 105.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A few isolated thunderstorms this evening mainly across the Pee
Dee in area of weak surface convergence. The latest HRRR model
has finally backed off on overnight convection streaming north
from the Low Country. Will keep a slight chance shower in the
southeast Midlands otherwise expect muggy conditions overnight
with temperatures falling into the low to mid 70s with some
high clouds.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
Weak boundary along with the remains of the MCS will be south of
the area Friday then drift slowly northward and into the CSRA on
Saturday. With temperatures each day in the mid to upper 90s
instability will be moderate to strong however a well defined
trigger will be lacking. As such have remained with slight
chance to low chance pops with the highest pops over the
southern Midlands and CSRA. Heat index values will be between
104 and 107 through Saturday.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Upper level ridge will be over the eastern US with a weak low
forming along the SE Coast then moving back inland during the
weekend and into next week. This will keep a moist and unstable
air mass over the region with chances of mainly afternoon and
evening convection each day. Temperatures through the long term
will remain in the mid 90s with heat index values in the low
100s.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
VFR conditions expected for most of the period. Current radar
indicates minimal activity at the moment. Some potential for
fog and stratus development late tonight, but confidence low.
Chances of convective coverage Friday afternoon appear too low
to include in the TAFs at this time.
EXTENDED AVIATION OUTLOOK...Restrictions possible each day in
early morning fog and mainly afternoon and evening
thunderstorms.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
SYNOPSIS...99
NEAR TERM...99
SHORT TERM...99
LONG TERM...99
AVIATION...99
Area Forecast Discussion
National Weather Service Caribou ME
938 PM EDT Thu Jun 28 2018
.SYNOPSIS...
Low pressure will cross the region tonight and exit through the
Maritimes Friday morning. A disturbance will cross the region on
Friday with afternoon showers and thunderstorms. A strong ridge
of high pressure over New England and much warmer temperatures
can be expected for late in weekend into early next week.
&&
.NEAR TERM /THROUGH FRIDAY/...
935 PM Update... Latest radar reflectivity imagery shows the
steadier rain continues to push east into New Brunswick as the
upper wave moves east. Still an isolated lightning strike along
the downeast coast and the coastal waters, so will continue
mention of isolated thunder there next hour or two. Otherwise,
what`s left of the rain will diminish by or shortly after
midnight. Plenty of low level moisture will result in patchy fog
overnight. No changes were made to overnight low temperatures
with abundant low level moisture remaining in place overnight.
This should inhibit temperatures from falling all that much from
current readings.
Looking ahead to tomorrow Friday, adjustments were made to pops
and weather, mainly to re-introduce thunderstorms into the
forecast. An upper disturbance and surface trof will cross the
region during the afternoon. SB Capes are forecast to range from
500 to 1000J per the GFS and even higher on the NAM. There is
some modest shear at 0-6 km on the order of 25 to 30 kts. There
will be some cooling in the mid levels in association with the
approaching upper disturbance with freezing levels around 10kft.
Based on the above parameters and forecast dew points in the 60s,
decision was made with this update to throw the mention of
gusty winds and small hail in any storms tomorrow afternoon. As
the disturbance tracks quickly east, any thunderstorms should
wind down rather quickly by early evening.
previous discussion
Surface and upper level low pressure will cross the region
Tonight then move off to the east Friday. Expect the heaviest
amounts of rain fall across the southern portion of the region,
especially along coastal sections. Also possible to get
thunderstorms across the southern and coastal areas this
evening. Do not expect any flooding issues at this time. Humid
conditions are expected tonight with low temperature around 60.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
Whats left of any shwrs and tstms from the prior aftn will be
exiting the FA to the E Fri eve, allowing for some clrg by late
Fri ngt. Sat will begin fair, then remnants of the MCS
originating from the Nrn plains tngt will apch the Rgn from the
W Sat morn with the associated MCV. Tstms will likely reform
across Nrn/Cntrl ptns of the FA in the heat of the day Sat aftn
with max MUCAPES in the 1000 to 1500 J/kg range. It`s erly to
mention enhanced wording with tstms given tstm potential Fri
aftn, but strong wind gusts and hail are possible with stronger
storms Sat aftn with mdtly strong 0-6km bulk shear. Once this
the MCV moves E of the FA Sat eve, skies should clear by late
Sat ngt. One consequence of this feature will be to delay the
arrival of hot air that will be sitting just S and W of our FA
this weekend, with Sun now looking like a recovery day from weak
llvl cool advcn Sat ngt. Still, though, hi temps Sun will be
abv seasonal norms.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
There is an outside chc of tstms clipping far Nrn ptns of the
FA, msly if the latest 12z GFS model run is correct in showing
another cluster of tstms from Cntrl QB movg toward the Gaspe
Peninsula, other models like the 12z ECMWF model run does not
show any shwrs/tstms, and with fcst 500mb hts fcst to be so far
abv normal with warm temps at this lvl by Sun eve, any
shwrs/tstms could be capped, but for now we went with slgt chc
Sun eve.
Otherwise, Mon looks to be at the least, very warm and humid, if
not hot, with a weak upper lvl disturbance from Cntrl Can
possibly resulting in aftn/erly eve tstms across Nrn/Cntrl ptns
of the Rgn, but confidence in this is low given how warm mid lvl
temps in the atmosphere will be, which could cap cnvctn unless
aftn sfc dwpts are in excess of 70 deg F. Longer range models
indicate that Tue could be as warm if not, warmer across the Rgn
then Mon with msly sunny skies and more in the way of downslope
winds. Wed too, may be hotter then we indicate, with long range
models holding off on any cold frontal passage on this current
model run til late in the day or Wed ngt. Aftwrds, Thu looks to
be a cooler and drier day with both the GFS/ECMWF actually
bringing hot air back for one more day Fri.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: Widespread IFR or lower conditions can be expected
at least the first half of the night in rain/low ceilings/patchy
fog. VFR to start on Friday but showers and scattered
thunderstorms will affect the terminals by afternoon with
potential MVFR or locally lower in and heavier showers or
tstms.
SHORT TO LONG TERM: Mainly VFR is xpctd for all TAF sites with
any MVFR vsbys and clgs associated with tstms and heavier shwrs
Sat aftn/erly eve and again Mon aftn.
&&
.MARINE...
NEAR TERM: Boundary layer conditions continue to reduce winds at
the surface with Sea surface temperature in upper 40s and air
temperature in mid 50s. So have used HRRR for winds into this
evening. For Waves: NWPS southern domain boundary (CAR53) wave
heights still running too high as is the case at 44027 & 44034.
So have initialized waves for tonight and Friday with NWPS then
reduced heights by 1 foot. Wind reports from ships in fetch area
south of the Gulf of Maine are compatible with Wave Watch winds
so expect model waves to fall in line later this evening. Total
Water Level: Have adjusted Base Tide Anomaly +0.20. Also
continue to adjust bias in tidal range in Bangor.
SHORT TO LONG TERM: No hdlns xpctd thru these ptns of the fcst
with marine fog becoming more of an issue from this weekend into
erly next week as progressively warmer and more humid air from
the SW moves ovr the waters. Went with about 80 to 90 percent of
WW3 wv guidance wv hts for this fcst update with fcst primary wv
pds msly in the 6 to 8 sec pd.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Beach Hazards Statement from 8 AM EDT Friday through Friday
evening for MEZ029-030.
MARINE...Small Craft Advisory until 3 AM EDT Friday for ANZ050>052.
&&
$$
Near Term...Duda/Mignone
Short Term...VJN
Long Term...VJN
Aviation...Duda/Mignone/VJN
Marine...Duda/Mignone/VJN
Area Forecast Discussion
National Weather Service Glasgow MT
714 PM MDT Thu Jun 28 2018
.DISCUSSION...
...Strong to severe storms with heavy rain expected this evening
for portions of northeast Montana...
715PM UPDATE
Main changes to the forecast were to update PoPs/QPF for current
showers on radar and towards the trend of the storms moving more
east as the evening wares on. A second wave of precipitation to
the west is moving into Petroleum and Phillips counties but this
is very light in comparison with only a couple thunderstorms
present in southern petroleum county. Most of the strong storms in
the east look to be out of northeast Montana by 11PM GAH
AFTERNOON DISCUSSION:
Theta-e ridge remains in place across eastern Montana this
afternoon with a surface low over north-central Wyoming allowing a
southeast surface flow to bring in some very moist air into the
region. Dewpoints in the lower 70s have reached Baker and mid 60s
just southeast of Fort Peck Lake. Precipital waters have exceeded
1.0" in the eastern zones with the potential to reach 2.0" near
Sidney this evening.
HRRR and other near-term models showing activity to really ramp
up at about 00z (6 pm) over mainly the eastern CWA. Supercells
will bring the threat of mainly damaging hail and winds. The QPF
continues to increase this evening, so a Flash Flood Watch has
been issued the southeast zones, mainly concerned about Sidney,
Glendive and points east from 6 pm-3 am. Rainfall amounts to 2.0"
not out of the question in this area.
Most of the activity moves into North Dakota around midnight. The
responsible upper trough will remain just west of the CWA Friday,
so more showers/thunderstorms are expected to linger. Some strong
storms near the ND border.
The trough drifts through eastern Montana Saturday but more energy
behind the trough keeps things unsettled through the weekend.
Troughiness will redevelop over western Canada/Pacific Northwest
by middle of next week, with another threat of
showers/thunderstorms. TFJ
&&
.AVIATION...
FLIGHT CAT: VFR-MVFR
DISCUSSION: Brief MVFR ceilings and visibilities are possible
with some of the steadier shower and thunderstorm activity that
occurs this evening as a low pressure system and cold front pushes
through the region. A few of these storms may be severe with
large hail, damaging winds, and heavy rain.
WIND: Will be east to northeast at 10 to 15 kts this evening,
becoming northwest late tonight. Note that with any thunderstorms,
winds could be gusty and erratic.
Maliawco/TFJ
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 3 AM MDT Friday for Dawson...Eastern
Roosevelt...Prairie...Richland...Wibaux.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Goodland KS
616 PM MDT Thu Jun 28 2018
.SHORT TERM...(This afternoon through Friday)
Issued at 150 PM MDT Thu Jun 28 2018
Overview: An upper level ridge over the Southern Plains (today)
will shift east across the central MS River Valley (tonight) and
into the OH Valley on Friday as an upper level trough progresses
eastward from the Pacific Coast to the Intermountain West.
Today and Tonight: With light W/WSW flow aloft on the NW periphery
of the upper ridge -- forcing will be confined to low-level
convergence invof a lee trough in eastern Colorado. With strong
insolation and a stout EML over the entire Tri-State area this
afternoon, diurnal destabilization will primarily be a function of
low-level moisture. 18Z SPC mesoanalysis data showed a dry low-
level airmass (characterized by H85 dewpoints of 6-10C) in place
across eastern CO and western KS. In the absence of moisture
advection, the thermodynamic environment over the Tri-State area
is expected to be marginally unstable (500-1500 J/kg) and capped.
Convection allowing models such as the NAM NEST and HRRR suggest
that isolated updrafts will develop upstream along the Palmer
Divide (and/or near Pueblo) around peak heating and propagate
downstream to the CO/KS border late this afternoon. Given weak
deep layer shear (and weak steering flow in general), updrafts
will be unorganized/short-lived in nature and will wane quickly
with loss of heating this evening. An isolated dry downburst
cannot be ruled out in eastern Colorado between 3-8 PM MDT given
T/Td spreads on the order of 40-70 degrees and extreme DCAPE
(2000-2200 J/kg) -- otherwise, severe weather is not expected.
Temperatures have already reached 100-106F north and east of
Goodland this afternoon and the Heat Advisory will be left as-is,
expiring at 01Z this evening.
Friday: Expect highs to be several degrees cooler in assoc/w H5
height falls attendant the approaching upper trough and increasing
mid/upper level cloud cover. 12Z guidance indicates that the lee
trough will shift eastward into central Nebraska and western
Kansas during the afternoon. Despite little discernible forcing
aloft, convection allowing models suggest that convection will
initiate along the surface trough around 23-00Z as insolation and
low-level convergence /moisture pooling/ erode convective
inhibition. Shear profiles and convective evolution suggest that
damaging winds will be possible with any deep convection that
develops late Fri aft/eve, primarily in northwest KS.
.LONG TERM...(Friday night through Wednesday)
Issued at 1230 PM MDT Thu Jun 28 2018
Friday night will usher in a few days of potential thunderstorms in
the Tri-State region as an upper-level trough approaches. This
trough will provide lee cyclogenesis which will lead to weak FROPA
and a good chance for severe thunderstorms late Friday evening. The
cold front will provide cooler high temperatures in the upper 80s to
lower 90s for most of the CWA through the weekend as the trough axis
traverses the area. Relatively strong upper-level winds from the
trough and persistent southerly low-level winds from cyclogenesis
will continue through Monday night which should provide enough
forcing for ascent and instability to keep thunderstorms, some of
which may be severe, in the forecast in the evening and overnight
hours. The strongest hazards from these thunderstorms would be
large hail and damaging winds.
Models are in agreement that upper-level ridging will build back up
past Monday throughout much of the southern Great Plains, bringing
with it higher maximum temperatures back into the mid 90s in our
area. However, model guidance becomes less clear on what impact that
will have on the chance for showers and thunderstorms getting into
the middle of next week. Continued south-southeasterly low-level
winds will likely keep enough moisture and instability in the
Central High Plains to make showers and thunderstorms possible
during this time, including on Independence Day. The timing for
these showers and thunderstorms would be during the evening hours.
It is possible that some of these thunderstorms could be severe, but
the predictability this far out remains too low to say much about
these storms with confidence. An upper trough moves east of the
region on Sunday, with zonal flow across the northern half of the
country as high pressure redevelops to the south early next week.
By Tuesday, a closed low enters the Pacific Northwest and
southwesterly flow forms aloft. This low quickly lifts northeast
into Canada as high pressure strengthens over the Plains and
dominates for the remainder of the work week. Overall, dry
conditions can be anticipated during the extended with warming
temperatures. However, as shortwaves traverse the High Plains and
moisture filters in underneath the ridge, there is potential for
some periodic showers and thunderstorms (but coverage looks to be
limited).
High temperatures gradually warm throughout the period, from the mid
to upper 80s on Sunday to the 90s on Wednesday. Low temperatures
range from the 60s to low 70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 532 PM MDT Thu Jun 28 2018
GLD will see VFR conditions through the 00Z TAF period with a
small cluster of thunderstorms immediately to the west of the
site expected to move across the site and dissipate by 02Z. After
02Z, VFR conditions with mostly clear skies are expected along
with southerly winds.
MCK will remain VFR with mostly clear skies and only high clouds
expected to move across the site. Winds will remain out of the
south.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...Heat Advisory until 8 PM CDT this evening for KSZ002>004-014>016.
CO...NONE.
NE...Heat Advisory until 7 PM MDT /8 PM CDT/ this evening for
NEZ079>081.
&&
$$
SHORT TERM...VINCENT
LONG TERM...PATTON
AVIATION...LOCKHART
Area Forecast Discussion...UPDATED
National Weather Service Huntsville AL
818 PM CDT Thu Jun 28 2018
.NEAR TERM...(Tonight)
Issued at 818 PM CDT Thu Jun 28 2018
Thunderstorms have come to an end across the Tennessee Valley as the
MCS (responsible for the 60+ reports across our area earlier
today) has sunk well southwest into Central Mississippi and South
Alabama. In its wake, a rain cooled, stable air mass has settled into
the region. Per the 01z SPC mesoanalysis, little/no CAPE is present
across all but far NW Alabama (along the MS/AL border) as this
previously mentioned thunderstorm activity has served to stabilize
the atmosphere. Temperatures (currently in the upper 60s to lower
70s) are actually at their coolest point of the day. With dewpoint
depressions around 0-1 degrees, these values should not drop much
tonight. The boundary layer moisture will serve to help promote
patchy fog late tonight -- especially in areas where some localized
clearing can take place. The is one of the primary questions for the
forecast tonight: how much of this lingering debris cloud shield will
dissipate. Current IR satellite trends suggest some decent clearing
may be possible, especially east of I-65. As such, have added a
mention of patchy fog in the forecast after 06z.
Despite the mostly stable environment, the potential for a few
isolated showers and storms are possible late tonight, thanks to a
weakening MCS currently over the lower Ohio Valley. Should the
remnants of this feature make it in, we`re not expecting any strong
or severe activity, however. Some of the mesoscale guidance, such as
the HRRR and NSSL-WRF suggest it may make it into NW Alabama around
06-09z, and thus have maintained a 20 PoP overnight for this reason.
Otherwise, minor tweaks were made, mainly to temperatures and cloud
cover.
.SHORT TERM...(Friday through Saturday)
Issued at 113 PM CDT Thu Jun 28 2018
The upper ridge will be building over the central and lower OH valley
Friday and shifting into the OH/PA area Saturday. Meanwhile, an upper
low will be developing, perhaps enhanced by the current MCS/MCV
moving southeast through our region now. This will produce widespread
convection, mainly to our south and southeast. Will maintain at least
low PoP, mainly during the daytime hours, but confidence is rather
low.
Our main impact weather will be excessive heat, mainly for our
northwest AL counties (the Shoals). After coordination with OHX, will
extend the current Heat Advisory through Saturday afternoon. Heat
index values of around 105 degrees is expected in these areas.
Overnight lows will be in the lower 70s this evening due to the rain,
but then will likely only dip into the middle 70s Friday night. Some
urban area will remain the 80s much of the night, with very high dew
points persisting during this period.
.LONG TERM...(Sunday through Wednesday)
Issued at 502 AM CDT Thu Jun 28 2018
The extended portion of the forecast will begin with the forecast
area located within a region of weak steering currents between a
strong 500-mb high over the northern mid-Atlantic region, a weaker
ridge over the southern Plains, and an inverted mid-level trough in
the vicinity of the northeastern Gulf coast. Although global
deterministic and ensemble model guidance exhibits temporal
variability normal for this time range and season, a consensus of
the solutions suggests that the inverted trough axis will retrograde
across the region on Monday-Tuesday, around the base of a
strengthening high over the eastern Plains.
Large scale ascent related directly to the existence of the trough
will be rather weak, but the relative minimal in subsidence should
support scattered-locally numerous showers and thunderstorms in the
very moist airmass (PWAT values in the 1.8-1.9 inch range) that will
be in place over the TN Valley. This activity will be strongly tied
to the diurnal warming cycle, with highest POPs during the daylight
hours and only a slight chance of lingering convection during the
00-03Z periods. With forecast soundings depicting weak lower-middle
tropospheric wind fields and seasonably high values of CAPE, the main
threats with any storms will be brief gusty winds, lightning and
locally heavy rainfall.
During the period from Tuesday-Wednesday, the inverted trough will
advance further westward and away from the region and we will
experience an increasing influence from a ridge extending from the
mid-MS Valley into the western North Atlantic. The coverage of
diurnal showers and thunderstorms will be reduced this period, and
mainly confined to far western portions of the CWFA. With the ridge
displaced to our north and stronger deep-layer easterly flow over the
TN Valley, highs will remain in the u80s-l90s, with lows in the
u60s-l70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 621 PM CDT Thu Jun 28 2018
Storms have come to an end early this evening across the region, with
only SCT decks of Cu and BKN decks of dense high clouds in their
wake. Clouds will gradually diminish this evening. However, models do
hint at the possibility of an additional round of -TSRA at KMSL btwn
06-09z. Have kept this at VCTS due a slightly lower confidence of a
storm directly impacting the terminal. Light fog will also be
possible around daybreak, before dissipating to VFR conditions after
sunrise.
&&
.HUN WATCHES/WARNINGS/ADVISORIES...
AL...Heat Advisory until 7 PM CDT Saturday for ALZ001>004.
TN...NONE.
&&
$$
NEAR TERM...AMP.24
SHORT TERM...17
LONG TERM...70/DD
AVIATION...AMP.24
For more information please visit our website
at weather.gov/huntsville.
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
649 PM CDT Thu Jun 28 2018
.SHORT TERM... (Through Late Friday Afternoon)
Issued at 344 PM CDT Thu Jun 28 2018
The complex of thunderstorms originating over eastern Nebraska and
western Iowa early this morning has matured into a well-organized
thunderstorm complex. This system is capable of producing damaging
winds and frequent lightning and will continue to be the focus this
afternoon into this evening.
As upper ridging continues to build in, a warm front draped across
the region will be the dividing line between sunny and warm
conditions through central Missouri, to slightly cooler and active
weather along and east of the Mississippi River. Mesoanalysis
continues to show a steep CAPE gradients centered over the CWA with
MUCAPE values exceeding 5000 J/kg over northeast Missouri and
trending down to near 3000 J/kg over Illinois. Capping has also
weakened and even eroded through much of the region.
High res guidance has struggled to recognize the origin and
evolution of this complex. HRRR only recently picked up on this,
while NAMNest was much further west. As upper ridging builds
northeast, relatively stable air will become more solidified over
central portions of the state. As a result, the MCS will continue to
track around the eastern periphery of the ridge and along the
instability gradient. Should thunderstorms survive, expect the line
to push along and east the Mississippi through about 02-03z before
exiting to the southeast.
Beyond this evening, skies clear and conditions calm with the next
concern being heat and humidity for Friday. As the warm front pushes
east, temperatures will climb well into the 90s, possibly touching
100 in spots. Provided dewpoints well into the 70s, heat indices
will likely become dangerous through the afternoon, mainly in far
east-central Missouri and into Illinois. Heat indices may exceed 110
degree east in many places in Illinois.
Maples
.LONG TERM... (Friday Night through Next Thursday)
Issued at 344 PM CDT Thu Jun 28 2018
(Friday Night - Saturday Night)
Main focus at the beginning of the extended will continue to be on
the ongoing heat wave. Have relatively high confidence in
temperatures and dewpoints on Saturday. Very hot and humid airmass
will remain in place as upper-level ridge slowly slides eastward
into the Ohio Valley. Probably will see some slight lowering of
dewpoints due to deeper mixing and soil moisture drying out ever so
slightly. All that being said, am expecting high temperatures on
Saturday in the low to mid 90s, with peak heat index values of 100-
110 across the area. Highest values are forecast for the St. Louis
metro area and portions of western Illinois. Because of two days of
expected HI values near or just above 110 degrees, will upgrade
these areas to an excessive heat warning.
(Sunday - Next Thursday)
At least a little relief from the oppressive heat is expected by
Sunday or Monday as a weak cold front attempts to move through the
CWA. Model guidance is in fairly good agreement that the front will
either just clear or at least make it into far southern portions of
the forecast area by Monday afternoon. Along with slightly cooler
air behind the boundary, an increase in overall cloud cover along
with chances for showers and thunderstorms should yield high
temperatures back into the upper 80s to low 90s by Monday. No
changes made to the heat headlines in terms of duration, but could
need an additional day (Sunday) for the advisory/warning if
confidence in temperatures increases.
Unfortunately, the brief reprieve expected from the really hot and
humid conditions on Monday will be very short lived. The mid/upper
level ridge elongates and strengthens toward the middle of next week
which should yield increasing temperatures with continued humid
conditions. Weak frontal boundary that went through as a cold front
Sunday/Monday is expected to retreat back northward as a warm front
on Tuesday. This boundary may provide a focus for showers and
thunderstorms as well.
As alluded to yesterday, no end in sight to the overall hot/humid
pattern with mid/upper level ridge really flexing its muscles nearly
from coast to coast.
Gosselin
&&
.AVIATION... (For the 00z TAFs through 00z Friday Evening)
Issued at 633 PM CDT Thu Jun 28 2018
KUIN/KCOU...VFR and dry thru the period expected. Winds will be
sely then become swly on Fri morning. There is some question
regarding fog development tonight. Believe that KCOU will be VFR
thru tonight. However, with the wrmfnt in the vicinity reinforced
by an outflow from ongoing storms, moisture may pool in the area
allowing fog to develop. KUIN has a better chance at fog
development late tonight into Fri morning given the precip this
afternoon. Confidence is too low to add to TAF attm, but will
continue to monitor and update as needed.
SPECIFICS FOR KSTL/KSUS/KCPS: Severe line of TSRA continues to
move south and southeast away from terminals. However, some
redevelopment north of terminals continues. Will keep TSRA mention
for a couple of hours, but activity shud gradually diminish and
exit the area. Otherwise, winds will become sly and perhaps swly
on Fri.
Tilly
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Heat Advisory until 10 PM CDT Saturday for Audrain MO-Boone MO-
Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-
Iron MO-Knox MO-Lewis MO-Lincoln MO-Madison MO-Marion MO-
Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike MO-Ralls
MO-Reynolds MO-Saint Francois MO-Sainte Genevieve MO-Shelby
MO-Warren MO-Washington MO.
Excessive Heat Warning until 10 PM CDT Saturday for Jefferson MO-
Saint Charles MO-Saint Louis City MO-Saint Louis MO.
IL...Heat Advisory until 10 PM CDT Saturday for Adams IL-Brown IL-
Pike IL-Randolph IL-Washington IL.
Excessive Heat Warning until 10 PM CDT Saturday for Calhoun IL-
Clinton IL-Greene IL-Jersey IL-Macoupin IL-Madison IL-
Monroe IL-Saint Clair IL.
Excessive Heat Warning from 11 AM Friday to 10 PM CDT Saturday
for Bond IL-Fayette IL-Marion IL-Montgomery IL.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Memphis TN
626 PM CDT Thu Jun 28 2018
.DISCUSSION...
Updated for 00z Aviation Discussion.
&&
.PREV DISCUSSION... /issued 554 PM CDT Thu Jun 28 2018/
UPDATE...Evening update.
Updated to adjust the forecast in accordance with the newly issued
Severe thunderstorm watch. This is a highly uncertain event, but
it appears another MCS has the potential to move into West
Tennessee, the Missouri Bootheel and Northeast Arkansas this
evening/overnight. Damaging wind will be the primary threat but
large hail is also possible. Ongoing convection could help
stabilize the airmass ahead of the approaching MCS limiting the
threat...keep an eye to the North.
.PREV DISCUSSION... /issued 348 PM CDT Thu Jun 28 2018/
.Widespread Dangerous Heat Expected Again on Friday....
Currently, temperatures at 3PM are in the low to upper 90s across
much of the area. The exception being portions of west Tennessee
that have seen convective activity this afternoon. Heat index
values across much of the area have been at or above 105 F for
much of the day. Jonesboro has been the hot spot with values
hovering around the 110 F mark over the past couple hours. A few
showers and thunderstorms have begun to fire up across west
Tennessee, but should remain below severe limits.
Short term...rest of today through Sunday...
Showers and isolated thunderstorms will continue through sundown
for areas in west Tennessee near the Tennessee River. The HRRR
continues to bring another complex of storms into our area around
midnight, but the general consensus has been towards a dry
forecast. Current thinking is that the ridge will build in
tonight, and any weaker convection will not be able to overcome
the cap. Went ahead and left a 20 POP in across the area to
account for the uncertainty.
Friday will be another scorcher. Forecast dewpoints will be in the
mid to upper 70s coupled with temperatures in the mid to upper
90s. At this point, areas across northeast Arkansas will likely
meet or exceed 110F tomorrow, prompting a heat warning. Since an
advisory is already out, no watch will be issued. Will let the mid
shift make the final call on the heat warning as models may back
off on the moisture field. Some showers and thunderstorms may
form under the weakest part of the ridge tomorrow afternoon,
mainly near the Tennessee River.
Models are hinting at an inverted trough sneaking under the ridge
over the weekend. This will likely increase rain chances and
cloud cover from east to west, which should offset some of the
heat for eastern portions of the area. For areas along and west
of the Mississippi River, more heat advisories may be needed.
Long term...Monday through Independence Day...
A ridge of high pressure will dominate the interior U.S. during
this time period. There is still some question as to how strong
the ridge will be for next week, as it may flatten out some.
Nonetheless, hot and humid conditions will continue with heat
index values above the triple digit mark during this time frame.
General airmass thunderstorms will be isolated and sporadic
through this period as well.
AC3
&&
.AVIATION... 18Z TAFs
VFR through the period...with the exception of convection early on
at TUP bringing conditions down to IFR/MVFR. Then next complex of
storms located just south of STL will move into at least VC at JBR
and MKL by midnight. Not sure on exact coverage by that time or
whether the activity will hold together near MEM. Later in the
period late isolated convection is possible near sunset again.
Winds light from the south or southwest with stronger gusts early
at TUP.
JAB
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...Heat Advisory until 8 PM CDT Friday for Clay-Craighead-
Crittenden-Cross-Greene-Lawrence-Lee AR-Mississippi-
Phillips-Poinsett-Randolph-St. Francis.
MO...Heat Advisory until 8 PM CDT Friday for Dunklin-Pemiscot.
MS...Heat Advisory until 8 PM CDT Friday for Alcorn-Benton MS-Calhoun-
Chickasaw-Coahoma-DeSoto-Itawamba-Lafayette-Lee MS-Marshall-
Monroe-Panola-Pontotoc-Prentiss-Quitman-Tallahatchie-Tate-
Tippah-Tishomingo-Tunica-Union-Yalobusha.
TN...Heat Advisory until 8 PM CDT Friday for Chester-Fayette-Hardeman-
Haywood-Lauderdale-Madison-McNairy-Shelby-Tipton.
Heat Advisory from 10 AM to 8 PM CDT Friday for Benton TN-
Carroll-Crockett-Decatur-Dyer-Gibson-Hardin-Henderson-Henry-
Lake-Obion-Weakley.
&&
$$
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
729 PM CDT Thu Jun 28 2018
.UPDATE...
Issued at 728 PM CDT Thu Jun 28 2018
Have updated PoPs/QPF this evening to basically go dry across the
MPX area the rest of the night. Yes a LLJ is still expected to
come up here with attendant steep lapse rates and very unstable
airmass. However, forecast soundings show this LLJ really just
advecting in a very hot and dry EML. At 7pm, the only CAMs really
handling the current situation well are the HRRR and experimental
HRRR and what they show fits in to our current thinking with how
things will unfold tonight with the developing MCS over eastern MT
racing across NoDak and into northern MN tonight, maybe grazing
our northern CWA in central MN.
&&
.SHORT TERM...(This evening through Friday)
Issued at 320 PM CDT Thu Jun 28 2018
The short term concern remains convective potential through the
night and heat concerns for Friday.
Northern MN convection problematic into the evening. HIRES models
diverge greatly on how evolution of this activity will occur. The
latest HRRR has this activity congealing into a weaker MCS and
treks it southeast clipping our eastern flank this evening. SPC
issued a severe thunderstorm watch for portions of northern MN
for ongoing convection. Still not completely buying the HRRR trend
at the moment. We will drop some mid range chance PoPs into the
eastern cwa into the evening.
Various HIRES CAMS were all over the place with development later
tonight. The Iowa complex will impinge warm frontal movement into
the evening, but will see some movement north along with the mid
level cap. Will continue to mention a chance of thunder developing
to into central MN overnight as this front lifts north. Very
unstable airmass with mid level lapse rates around 8.5 C/km later
tonight. Severe thunderstorms possible if we do get activity to
generate with damaging winds, large hail and heavy rain the main
threats. Again, some CAMS indicating the potential of a MCS
developing over eastern MN/western WI later tonight. Strong low
level jet progged around 50 kts impinging on the boundary as
well. Should be enough to generate at least some scattered
thunder. With the divergent short term CAMS will have to continue
a mid range PoP trend. The latest HRRR has come back full circle
to developing the North Dakota system which looks most likely.
Friday should start out with any convection exiting the far
eastern cwa early. Northern MN system may drop outflow into
northern CWA and I did leave the Excessive Heat Watch going for
the northern and western areas for now. Was most confident with
the southern areas meeting warning criteria so we issued that
now. We will see mid level warm air invade the region with the GFS
indicating +16 to +18c at 700s mb moving across the cwa. This
should preclude any convective development until Friday evening.
Southerly winds should mix south with some gusts to 30 mph
possible over the southern half of the cwa Friday afternoon. We
expect highs warming through the 90s region wide with heat
indices 105-110F likely in the warning area.
.LONG TERM...(Friday night through Thursday)
Issued at 320 PM CDT Thu Jun 28 2018
Friday evening should remain capped initially and develop at least
some scattered convection over the western cwa overnight. The
front is progged into central MN by 12z Saturday. The severe
weather threat remains until fropa along with the potential of
heavy rain. We will have to monitor overall model trends and see
if we can focus on better hazardous weather threats through
Saturday night.
We should see drying occur into Monday with little in the way of
cooling indicated. Dewpoints are not expected to dry out too much
with the current trend expected to continue through much of next
week. Temperatures remain above normal as well.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 710 PM CDT Thu Jun 28 2018
Main change with 00z TAFs was to pull back on thunder mention
tonight. We will still have a strong LLJ working up here during
the night, but looking at soundings, it will be advecting a hot
and dry EML in here. At the start of this period, the HRRR and
experimental HRRR are really the only CAMs that have a handle on
what is currently going on and agree with their assessment that
the activity over eastern Montana will develop into a squall line
that will race across North Dakota into northern MN tonight,
leaving AXN really as the only TAF that may be impacted by this,
though latest trends from the HRRR keep the MCS north of even AXN.
Friday will feature very strong capping, so no TS activity is
expected during the TAF period. Did go a little higher than
guidance on wind speeds tomorrow given mixed winds we are seeing
on BUFKIT profiles.
KMSP...Some low level wind shear is expected Friday, but with
minimal directional change and gusty winds expected, don`t think
shear will be strong enough to warrant a WS mention, so removed
that from the TAF as well.
/OUTLOOK FOR KMSP/
Sat...VFR. Chc TSRA. Wind SW bcmg W 10-15 kt.
Sun...VFR. Chc TSRA. Wind WNW 5 kt.
Mon...VFR. Wind SW 10G20 kt.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Excessive Heat Warning from 11 AM to 10 PM CDT Friday for
WIZ023>028.
Excessive Heat Watch from Friday morning through Friday evening
for WIZ014>016.
MN...Excessive Heat Warning from 11 AM to 10 PM CDT Friday for MNZ051-
059>063-066>070-074>078-082>085-091>093.
Excessive Heat Watch from Friday morning through Friday evening
for MNZ044-045-049-050-052-053-057-058-065-073.
&&
$$
UPDATE...MPG
SHORT TERM...DWE
LONG TERM...
AVIATION...MPG
Area Forecast Discussion...correction
National Weather Service Paducah KY
713 PM CDT Thu Jun 28 2018
CORRECTED AVIATION DISCUSSION
.UPDATE...
Issued 713 PM CDT Thu Jun 28 2018
A severe mesoscale convective system will barrel southward through
much of the PAH forecast region this evening. The very unstable
atmosphere will be favorable for this "wind machine" to continue all
the way through to the AR/TN state lines before midnight. Severe
weather is likely across a wide swath of the county warning area.
Also updated aviation discussion.
&&
.SHORT TERM...(Tonight through Saturday night)
Issued at 312 PM CDT Thu Jun 28 2018
Storms and heat are the main forecast concerns. A weak surface
boundary remains quasi-stationary from around kmdh to just
northeast of kpah to the khop area. Storms continue to regenerate
along parts of this boundary, mainly in western KY. There is
little indication this boundary will move tonight, since the upper
level flow will become parallel to the boundary. Therefore,
isolated to scattered storms remain possible through the night.
Another fly in the ointment is the thunderstorm complex over ne
Missouri. None of the 12z model runs (including href members)
initialized this storm complex. However, the 18z hrrr is the first
model to capture these storms. The hrrr brings these storms
southeast along the aforementioned surface boundary this evening.
Given the orientation of the boundary parallel to the upper flow,
some heavy rainfall amounts will occur if storms continue to train
along it. There is also the potential for isolated wind or hail
events, similar to the multi-cell severe events earlier today. The
air mass remains very unstable near the boundary, due partly to
dew points around 80 degrees.
On Friday, the 500 mb high will build over our region. This will
suppress most convective activity compared to the last few days.
However, there are some indications the weak surface boundary
will still linger over our region Friday. Given the highly
unstable air mass, a few storms may pop up. The 12z href mean qpf
hints at convective activity Friday, though not nearly as strong
as this afternoon.
As far as the heat goes, the 80 degree dew points observed today
are not a good omen for Friday or Saturday. The model guidance
indicates widespread mid to upper 70s dew points both days. High
temps in the mid 90s are expected in much of the area both days.
This yields heat indices over 105 in all areas, and locally over
110 on Friday. An upgrade to an Excessive Heat Warning may be
needed for parts of the area, primarily where dew points have
been in the lower 80s from kmdh to kpof. Little if any convection
is forecast to tamp down heat indices on Saturday.
.LONG TERM...(Sunday through Thursday)
Issued at 312 PM CDT Thu Jun 28 2018
Heat and humidity will continue through the long term period.
Isolated thunderstorms will be possible through the period,
especially late Sunday into Tuesday, when a 500 mb shortwave
will move east across the upper Mississippi Valley and Great Lakes
region. This shortwave will flatten the 500 mb ridge, sending a
weak surface boundary into our region. A light east to southeast
wind flow is expected for much of the long-term period. Temps
should be a few degrees lower next week, but no change in dew
points is expected. Heat indices are forecast to range from 100 to
105 each afternoon next week.
By Thursday, the ensemble means of the gfs and ecmwf have been
hinting that the 500 mb ridge will begin to retrograde to the
Rockies. This may lead to some weak troughing in the vicinity of
the Appalachians. Pops will be slightly higher Thursday, with
just a slight drop in heat indices.
&&
.AVIATION...
Issued at 713 PM CDT Thu Jun 28 2018
An MCS will surge southward through a wide swath of the region this
evening, creating a hazard to aircraft. IFR conditions and high
winds are likely at the KCGI/KPAH TAF sites by mid-evening,
associated with a line of severe tstms. East of the Wabash River,
high winds are less likely this evening. In the wake of this system,
winds should be quite variable in direction as conditions gradually
recover to VFR, with an eventual recovery to a light south to
southeast wind and a dropoff in pcpn chances during the day Fri.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...Heat Advisory from 10 AM Friday to 8 PM CDT Saturday for
ILZ075>078-080>094.
MO...Heat Advisory from 10 AM Friday to 8 PM CDT Saturday for MOZ076-
086-087-100-107>112-114.
IN...Heat Advisory from 10 AM Friday to 8 PM CDT Saturday for INZ081-
082-085>088.
KY...Heat Advisory from 10 AM Friday to 8 PM CDT Saturday for
KYZ001>022.
&&
$$
UPDATE...DB
SHORT TERM...MY
LONG TERM...MY
AVIATION...DB
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
815 PM EDT Thu Jun 28 2018
.UPDATE...
Deep moisture and weak westerly flow allowed for scattered
to numerous thunderstorms to develop across the area this
afternoon. The majority of these storms have dissipated,
with the exception of an areas of storms lingering along an
outflow boundary over the Nature Coast counties. Overnight,
these storms will generally continue to dissipate. The one
concern is a strong outflow boundary moving south through
the Florida Panhandle producing a line of thunderstorms. The
HRRR is indicating that these storms could work south
through the Tampa Bay area through the overnight hours,
however other high resolution models confine the overnight
convection to the Gulf waters. In addition, the storms
currently over Levy and Citrus counties will likely
stabilize the environment to some extent, preventing the
outflow from staying intact this far south. As such, there
is some uncertainty about storm chances overnight, but the
chance is not zero. Rain chances during the early morning
hours were left alone for now, but the progress of the
outflow boundary will continue to need to be monitored.
A few adjustments were made to the rain chances forecast
for the next couple of hours to keep up with radar trends.
No other changes are planned for the evening update.
&&
.AVIATION...
Generally VFR conditions will hold overnight as the
majority of thunderstorms have cleared out of the area.
Late night/early morning thunderstorms cannot be ruled out
moving south through the Tampa Bay area before sunrise.
Showers and thunderstorms will develop near the coast by
late morning on Friday, then will expand inland through the
afternoon, with reduced flight categories possible as storms
move overhead.
&&
.MARINE...
A ridge of high pressure will hold over the southern Gulf of
Mexico through Friday night with continued westerly flow.
Morning showers will develop over the eastern Gulf and will
generally move inland by the early afternoon. The ridge will
lift into the northeastern Gulf this weekend, with lighter
and more variable flow, and increased thunderstorm coverage.
Winds and seas will stay below headline criteria outside of
thunderstorms.
&&
.Preliminary Point Temps/PoPs...
TPA 80 90 79 90 / 30 70 40 60
FMY 76 91 77 91 / 40 70 50 60
GIF 75 91 75 92 / 30 80 60 80
SRQ 80 89 79 89 / 40 70 50 50
BKV 76 90 75 91 / 50 70 40 80
SPG 80 91 79 91 / 40 70 50 50
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...Beach Hazards Statement through Monday evening for Coastal
Charlotte-Coastal Lee.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE...18/Fleming
UPPER AIR...42/Norman
DECISION SUPPORT...24/Hubbard
Area Forecast Discussion
National Weather Service Tucson AZ
845 PM MST Thu Jun 28 2018
.SYNOPSIS...A slow moisture increase will bring a chance of
thunderstorms over the next few days, favoring border areas and
mountain locations. As this happens, temperatures will fall back to
average late June/early July levels over the weekend.
&&
.DISCUSSION...A fairly active afternoon/early evening especially
across southern Cochise County where the bulk of the thunderstorms
were today. A few localized rain reports of 0.50" to 1.00" with
these storms generally in the Sierra Vista and Hereford areas given
the slow storm motions. Latest KEMX radar imagery still showing a
few showers and embedded thunderstorms across SW Cochise County due
to residual outflow boundaries bouncing around. However, these
should continue to diminish over the next few hours with plenty of
residual debris cloudiness overnight for eastern areas.
Meanwhile, a fairly pronounced surge of moisture from the Gulf of
California accompanied by breezy winds, patchy areas of blowing dust
and somewhat reduced visibility of around 10 miles has just moved
into the Tucson Metro from the southwest. Surface dewpoints have
jumped up into the mid to upper 50`s in Tucson over the past hour
with PWAT values now about 1.1 inches per GOES Total precipitable
water. Any blowing dust should rapidly diminish this evening.
Otherwise, the increased moisture will lead to more isolated to
scattered thunderstorms Friday afternoon and evening especially east
of Tucson. Made just a few tweaks to the forecast overnight to
account for current trends, otherwise no updates.
&&
.AVIATION...Valid through 30/06Z.
Isold -TSRA near International Border including KDUG thru 29/06Z.
Isold -TSRA Friday afternoon east and south of KTUS. Gusty SWLY/WLY
SFC winds at 10-18 kts this evening becoming SLY 5-15 kts overnight.
Gusty outflow winds will be likely in and around thunderstorms thru
this evening and once again on Friday afternoon. Aviation discussion
not updated for TAF amendments.
&&
.FIRE WEATHER...Southerly flow will continue to draw moisture into
our area tonight into Friday. Isolated thunderstorms near the
International Border generally from Nogales to Douglas. Chances will
expand to include the Tucson vicinity and eastward Friday evening
into Saturday. Thunderstorm chances then become more focused across
locations east and south of Tucson and the White Mountains Sunday
and into early next week. 20-foot winds will generally remain below
15 mph, except for in and around thunderstorms where gusty outflow
winds may occur.
&&
.PREV DISCUSSION...Cu field is developing on schedule (as of 21Z)
across far southeast Arizona within the axis of deepest moisture.
More robust convection is located about 100 miles south of the
US/MEX border in Sonora, Mexico per IR imagery. Nothing in the way
of measurable precip across Cochise or Santa Cruz Co`s as of yet,
but the last several runs of the HRRR as well as latest UA WRFs
continue to suggest additional development through late afternoon.
Despite the early morning increase in dewpoints, most sites have
mixed out with dewpoints in the 40s suggesting a dry sub-cloud layer
that`s favorable for gusty winds. I maintained 10-20 PoPs along the
border but also mentioned some patchy blowing dust as a possibility
through early evening.
Friday continues to look favorable for storms across portions of
southeast Arizona, as the combination of outflows from tonight`s
storms as well as more favorable southeast flow should import
additional moisture into the area. The greatest areal coverage
appears to be from Cochise/Graham Co eastward into New Mexico,
although mountain cu and even a stray shower or storm can`t be ruled
out on the Catalina or Santa Rita Mountains. PoPs in these areas
raised slightly based on today`s 12Z HREF and NBM. Like today, gusty
winds and patchy blowing dust are possible.
Saturday is a bit more of a mystery than it was a few days ago.
Synoptic models (particularly the GFS) are no longer suggesting a
widespread plume of deeper moisture across the area, but are instead
showing this axis shifting eastward into New Mexico as a trough (and
drier air) moves inland through California. Somewhat hard to imagine
that any leftover moisture from Friday`s convection would be wiped
clean by Saturday such that we don`t see any storms across the area,
and I`ll maintain the climo-like PoPs for Saturday
afternoon/evening. Finally by Sunday into Monday it looks like the
troughing and dry air will win out with both being relatively quiet.
A return to a more favorable flow looks likely by the middle of next
week with daily storm chances each afternoon.
As for temperatures, increased moisture is already having an impact
on afternoon highs with many lower desert sites just barely getting
above 100 degrees today (compared to well into the 105-110 degree
range earlier this week). Similar highs (near 100 give or take a
degree) are expected Friday/Saturday, followed by a slight warmup
next week.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
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