Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 07/08/22
Area Forecast Discussion
National Weather Service North Platte NE
628 PM CDT Thu Jul 7 2022
.SHORT TERM...(This evening through Friday night)
Issued at 428 PM CDT Thu Jul 7 2022
The primary forecast concerns to round out the week revolve around
precipitation chances/amounts, fog, and rebounding temperatures. The
stagnant, soupy air mass that has resulted in localized torrential
rainfall slowly gives way to a powerful upper ridge the next couple
days. Thunderstorm chances continue tonight and somewhat tomorrow,
then the heat really gets turned up over the weekend. Meanwhile,
will be monitoring for fog development tonight into the morning.
This evening and tonight... The quasi-zonal upper pattern begins its
transition to northwest flow tonight with the building Rocky Mtn
ridge, but nearly stationary surface fronts straddle the northern
and southern edges of the forecast area. As with any weakly forced
environment, CAMS have had trouble latching on to any one outcome.
Solutions range from widespread activity lasting for hours to
virtually no precipitation at all. The precip forecast generally
follows current trajectory of a couple distinct waves of iso/sct
thunder across the northern and eastern Sandhills. Also included
schc PoP in the panhandle and southwest to account for potential
overspreading from activity over the higher terrain. Main concern
with any thunder will continue to be locally very heavy rain, given
slow storm motion (<10 kts), near record PWAT (1.8 in.), weak flow
in the mid levels to limit high winds, and water loading to limit
large hail production. With that said, will forgo any flood
headlines as most impacts have been very isolated due to soil
conditions in the Sandhills and the current drought status. Thinking
any activity overnight should be isolated at most and likely
dissipating as forcing weakens further and elevated instability
wanes. As for fog production, guidance suggests a rather wide swath
across the Sandhills where surface winds stay very light out of the
east. Considering pockets of recent very heavy precip, some moisture
trapping is also likely. No official mention in the forecast package
was made where and when fog will affect due to the conditional
nature and whether stratus will be favored instead. Trends will
definitely need monitored this evening and tonight for potential
inclusion to the forecast. Little change was made in min temps,
which generally follow the lower and mid 60s. These values lined up
with the narrow NBM envelope as well as MOS guidance.
Friday... The northern boundary drifts south and should ultimately
fall apart over the Sandhills. Nonetheless, a front draped along the
lee of the Rockies may be enough to spur some thunder that meanders
into the panhandle or far southwest Neb later into the evening. Left
schc PoP for areas along/west of Hwy 61. Whatever shower or storm
that works into the area may produce gusty winds as soundings show
somewhat drier low/mid levels compared to those as of late.
Otherwise, conditions begin the transition to full-fledged
summertime weather as highs break the 90 degree mark again in the
west and upper 80s east. Near surface winds remain out of the
southeast, which keeps the humidity factor alive.
.LONG TERM...(Saturday through Thursday)
Issued at 428 PM CDT Thu Jul 7 2022
The main story over the weekend and early next week revolves
around the anomalous upper ridge and the attendant heat wave.
Forecast h5 heights near 600dm correlate to 99%ile of climo over
the central Plains. A surface warm front is also progged to cross
the central/northern Plains, when combined with strengthening
southerly flow at H85, will produce strong WAA. Temps at H85
should surpass 27C on Saturday and 30C on Sunday. With generally
fair conditions overhead, these values should translate to
widespread highs in the mid/upper 90s and lower 100s respectively.
Will need to watch for heat headlines on Sunday as prelim heat
index values meet the guidelines for the eastern half of the CWA.
Toward midweek, the ridge retreats to the Great Basin and Four
Corners region as a surface cool front swings through the central
Plains. The front not only brings some relief to the possible
extreme heat, but also increases the precip potential.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 625 PM CDT Thu Jul 7 2022
Currently VFR conditions at TAF sites but radar shows some
clusters of thunderstorms off to the west, particularly one
cluster near Pine Ridge that has good indications for winds
exceeding 50kt. The environment becomes less favorable to support
these storms as they make eastward progress so will not include
any mention in TAFs at issuance and will amend as radar trends
indicate.
Any storms will dissipate early tonight with light winds and
generally clear skies.However the boundary layer is quite moist
and expect patchy fog will develop toward daybreak with a plume of
stratus pushing in from the east. Expect MVFR vsbys at KLBF but no
CIG, while expect MVFR/IFR VSBYs and CIGs at KVTN. Any fog/stratus
will dissipate Friday morning with VFR conditions expected through
the end of the valid period.
Outside of thunderstorms, winds will be light through the valid
period with little impact to aircraft operations.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...Snively
LONG TERM...Snively
AVIATION...MBS
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
634 PM CDT Thu Jul 7 2022
.SHORT TERM...
Issued at 315 PM CDT Thu Jul 7 2022
Through Friday night...
The primary forecast concern centers around the threat of
excessive rainfall amounts with any showers and thunderstorms
tonight into Friday morning.
We are currently watching a remnant MCV apparent in the
satellite imagery shifting eastward across the Mississippi river
just south of KDVN. An extensive cloud shield, and areas of
showers extends southeastward from this feature over much of my
southern counties. Conditions are thus a few degrees cooler and a
bit more stable in these areas. Conversely, partly sunny skies
along and north of I-88 have helped temperatures rise into the low
to mid 80s amidst lower 70 degree dewpoints. While mid-level
lapse rates are poor across this area, recent modified AMDAR
soundings from MDW suggest that these slightly warmer and very
moist surface conditions is sufficient to support near surface
based instability. For this reason, we will need to monitor far
northern IL (along and north of I-80) for some scattered shower
and storm development late this afternoon into this evening as the
remnant MCV shifts eastward along the I-80 corridor over the next
few hours. While severe weather is not expected with any storms
that develop, very heavy rainfall would be likely given the
tropical airmass overhead, that features precipitable water
values around, or even a bit above 2".
Additional showers and thunderstorms will be probable across
portions of our area late tonight into Friday morning as another
disturbance shifts into the Corn Belt. While uncertainty remains
with the actual evolution of this overnight activity, it appears
that areas near and south of I-80 could be in target area for
some periods of heavy rain producing showers and thunderstorms
after midnight tonight through early Friday morning. As mentioned
above, the atmosphere will remain primed (with tropical
precipitable water values in excess of 2") to support very heavy
rainfall rates. This is concerning as any slow moving storms that
move over the same areas could produce some areas of excessive
rainfall and possible flash flooding. In spite of this possibility,
we have opted to hold off on issuing a flood watch mainly due to
continued uncertainty on the exact placement of this heavy rain.
We will therefore allow the evening shift to get a handle on
observational trends into this evening to assess whether a watch
will be needed for southern parts of the area.
The rain threat will end from northwest to southeast across the
area into Friday afternoon. Thereafter, expect cooler weather with
breezy northeasterly winds off of Lake Michigan. The only negative
to these winds, will be the increased threat of rip currents due
to large waves for any beach goers late Friday afternoon into
Saturday morning.
KJB
&&
.LONG TERM...
Issued at 315 PM CDT Thu Jul 7 2022
Saturday through Thursday...
After Friday`s shower activity clears the area, high pressure will
settle in over the region and lead to a rather pleasant weekend with
mostly clear skies and high temperatures topping out in the 70s to
low 80s on both Saturday and Sunday. Onshore flow is expected to
prevail throughout the day on Saturday, and accordingly, the coolest
temperatures (low 70s) will be found in the vicinity of the Illinois
and Indiana lakeshore. Return flow on the back side of the
surface high will turn surface winds southeasterly and eventually
southerly on Sunday, but the prevailing synoptic winds should
still be weak enough for a lake breeze to develop and push inland
a bit from the Illinois lakeshore, which is where Sunday`s coolest
high temperatures should occur.
Monday certainly appears to be the most interesting day forecast-
wise in the extended forecast period as an upper shortwave swings
through the Upper Midwest while a cold front at the surface makes a
push southeastward into our forecast area. There may ultimately end
up being two chances to see showers and storms in our forecast area
on Monday, but both of these chances appear to be highly
conditional. The first of these chances would come during the
morning and early afternoon and would be tied to whatever emerges
out of Sunday night`s convective activity in Minnesota. If an
organized MCC develops in a location where it could conceivably
track towards our CWA overnight Sunday into Monday morning, then
it`s possible that some decaying convection could sneak into the
northern third or so of our CWA sometime Monday morning. However,
most guidance that is currently available suggests that this
activity would either remain north of our CWA and/or outpace the
southeastward-sagging MUCAPE reservoir and dissipate before it got
to our doorstep, so think that any chances to see rain Monday
morning or early Monday afternoon appear to be rather minimal at
this time.
Assuming that the earlier convective activity doesn`t pan out, or at
the very least, doesn`t muddle the forecast picture too much for
later in the day, the better chances for us to get in on any showers
or storms should come towards the late afternoon and evening on
Monday as the aforementioned cold front passes through the area.
Prior to the arrival of the front, Monday afternoon should be warm
and fairly humid with temperatures favored to reach the upper 80s
and possibly the lower 90s across the much of the area while dew
points look to climb above the 70 degree mark across a sizable
portion of our CWA. Plenty of moisture will be available to
support the potential development of showers, and ample
instability should become available by the late afternoon to
support the development of thunderstorms too. However, it appears
that convection could struggle to actually initiate along the
front as it moves through the region as southwesterly to westerly
surface winds immediately ahead of the front should serve to limit
the amount of surface convergence along it. With the core of the
forcing for ascent associated with the upper shortwave expected to
remain to our north, there may not be much additional support for
lift to augment the weak convergence along the front and assist
surface-based parcels with reaching their level of free
convection. Considering that there`s a fair likelihood of at least
a modest amount of convective inhibition still hanging around by
the late afternoon and into the evening, the overall lack of
robust forcing could result in convection failing to initiate
along the front, which would result in most or all of our area
remaining dry on Monday. However, if something can get going
either in our CWA or just upstream in Wisconsin prior to diurnal
stabilization occurring after sunset, there will be plenty of deep
layer shear for developing thunderstorms to work with, so
forecast trends will bear watching over the coming days. At this
time though still being four days out from Monday, there`s still
too much uncertainty to say anything with much confidence. Left
the blended slight chance and chance PoPs generated by the NBM
untouched as they seem appropriate for now given the existing
uncertainties.
Beyond Monday, upper ridging will start to build across the
southwestern CONUS. Temperatures look favored to end up at or
just below normal towards the mid-late week with predominantly
northerly to northwesterly flow through much of the atmospheric
column not affording any opportunities for warmer temperatures to
our west and south to advect into the region until beyond the end
of the current extended forecast period. A backdoor cold front may
also drop through the area sometime in the mid-late week time
frame and provide a reinforcing shot of relatively cooler and
drier into the region on either Wednesday or Thursday. It appears
that there may also be a lower-end chance for some rain showers to
be squeezed out along this front as it moves through the area,
though the lack of quality moisture available during the time of
the frontal passage suggests that getting rain from this may be
hard to come by, and if it does occur, it probably won`t be very
meaningful. Stuck with the default NBM PoPs for Wednesday and
Thursday, which currently keep the mid-late week forecast void of
any formal rain chance mentions.
Ogorek
&&
.AVIATION...
For the 00Z TAFs...
Aviation Forecast Concerns:
* A few periods of showers from this evening through Friday
midday. TSRA threat low but non-zero across terminals,
especially early Friday morning.
* Period of MVFR ceilings likely Friday from prior to sunrise
through the afternoon. IFR ceilings also possible during the
morning.
* Light mainly easterly winds become north-northeast Friday, with
some gusts around 20 kt possible in the afternoon.
Early evening surface analysis indicates a west-east stationary
frontal boundary from central MO through far southern IL/IN, while
weak surface high pressure was over the Great Lakes. North of the
stationary front, several small mid-level disturbances (remnant
MCVs from Plains convection) were noted in radar imagery, with one
such feature currently tracking across central IL and another
along the IA/MO border. Each of these will produce areas of
showers and a few isolated thunderstorms as they track into the
region this evening. Greatest coverage is expected to remain
generally south of the terminals, though scattered coverage across
northern IL appears to warrant at least a VCSH mention into
tonight. A more robust mid-level wave across the mid-Missouri
Valley will approach the region late tonight, and should produce
greater coverage of showers through midday Friday before moving
east of the area later in the day. Thunder potential looks to be
better south of the terminals across central IL/IN, though can`t
rule out isolated thunder farther north especially early Friday
morning as this deeper wave approaches.
Guidance is in good agreement in development of MVFR ceilings with
the better precipitation coverage Friday, with some models
supporting a period of IFR ceilings during the morning. Increasing
northeast winds Friday afternoon/evening should eventually pull in
some drier air and allow for mixing/lifting ceilings later in the
day and evening for the Chicago terminals.
Ratzer
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...Beach Hazards Statement...ILZ006-ILZ103-ILZ104...4 PM Friday to
1 PM Saturday.
IN...Beach Hazards Statement...INZ001-INZ002...10 PM Friday to 10 AM
Saturday.
LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742...4 PM Friday to 10
AM Saturday.
Small Craft Advisory...LMZ743-LMZ744-LMZ745...10 PM Friday to 10
AM Saturday.
&&
$$
Visit us at weather.gov/chicago
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/NWSChicago
www.twitter.com/NWSChicago
www.youtube.com/NWSChicago
Area Forecast Discussion
National Weather Service Phoenix AZ
408 PM MST Thu Jul 7 2022
.UPDATE...Updated 00z Aviation Discussion.
&&
.SYNOPSIS...
Unusually dry conditions will persist through the remainder of the
week with only isolated showers and storms returning to eastern
Arizona over the weekend. Temperatures will continue to increase
with lower elevation communities breaching 110 degrees by Friday.
These type of above normal readings should last through the middle
of next week. As moisture seeps back into the region next week,
mountain storms should become more expansive with impacts beginning
to work back into lower elevations.
&&
.DISCUSSION...
Dry southwest flow continues with PWAT values at near 0.5" based
on ACARS soundings. Surface dew points are also low, with values
in the 30s for much of the area. The latest visible satellite
imagery shows Arizona to be nearly cloud free. This very dry
pattern will remain in place through Friday as deep southwesterly
flow persists on the western periphery of a high pressure system
retrograding from the southern plains. H5 heights will steadily
increase closer to 595dm by Friday afternoon with forecast
soundings suggesting a growing midtropospheric subsidence
inversion. As a result, probabilities across lower elevations for
110F+ high temperatures Friday jumps into a 30-70% range.
Further westward expansion and intensification of the subtropical
anti-cyclone is strongly supported by all ensemble suites over the
weekend with central H5 heights around 598dm becoming parked over
the four corners. Although these H5 heights will be reaching toward
the climatological 99th percentile, thermal profiles in the H8-H7
layer are not exhibiting a directly analogous trend peaking only
around the 90th percentile and restricting forecast highs to several
degrees below record territory. EFI values for surface
temperatures are similarly elevated (but not particularly unusual)
with values of 0.6 to 0.7 across the area. Nevertheless, it will
still be hot (~5F above normal) and readings flirting with
excessive heat criteria. Current official NBM forecasts align near
the 75th percentile of the entire ensemble spread, so there is
still some small opportunity readings could breach into excessive
thresholds over the weekend.
Weak east to southeast flow will allow for low level moisture to
gradually increase over the weekend and into next week. Moisture
levels (~8-10 g/kg in the boundary layer) should allow for a
resumption to the low probability of afternoon/evening mountain
convection and storms. Given this marginal moisture profile along
with warming midlevel temperatures, the lower desert environment
will remain hostile towards additional storm development through
early next week.
By the middle of next week ensemble guidance is in relatively good
agreement that the upper level high will migrate slightly
northward, which should result in marginally more favorable
moisture and instability profiles as well as increased wind shear.
If this slight pattern shift materializes it would open the door
to storm activity in the lower deserts as well assuming gradually
improving moisture profiles via outflows and advection. NBM
precipitation probabilities during this period increase to 15-25%,
which seems reasonable given the uncertainty and lead time. Some
ensemble guidance is less optimistic with the movement of the
upper level high, which would keep conditions hotter and drier
than average, but at this range it is difficult to determine which
solution will be more accurate.
&&
.AVIATION...Updated at 2305Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation weather concerns expected through Friday. Westerly
winds between 7-10 kts with a few occasional gusts between 15-20
kts will be common through this evening before diminishing in
speed overnight. Winds will become easterly around 12z Friday
morning with speeds aob 5 kts then switch to westerly between late
morning and early afternoon with speeds generally between 7-10
kts. However, some occasional afternoon gusts between 15-20 kts
will be possible. Skies will remain mostly clear through the
period.
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns expected through Friday. Winds will
generally retain a southeasterly component at KIPL and southerly
component at KBLH. At KBLH, some gusts of around 20 kts will
persist into the evening before subsiding, with another around of
breeziness expected once again Friday afternoon. Skies will remain
mostly clear through the period.
&&
.FIRE WEATHER...
Isolated thunderstorm coverage will gradually return to far eastern
districts this weekend, but dry conditions will persist until then.
Even as storms return, wetting rainfall potential remains limited.
Somewhat better thunderstorm and rainfall coverage may return to
eastern areas next week, especially by Wednesday. Minimum
afternoon humidity levels will fall into the teens, however higher
terrain locations of eastern districts should see humidity values
closer to a 20-30% range next week as moisture starts to return.
Overnight recovery will be mostly poor to fair in a 20-50% range.
Some enhanced upslope afternoon breeziness will be common, but
gusts should generally not exceed 20-30 mph.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Hodges/18
AVIATION...Lojero
FIRE WEATHER...Hodges/Iniguez/18