Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/26/21
Area Forecast Discussion
National Weather Service La Crosse WI
1103 PM CDT Tue May 25 2021
.UPDATE...
Issued at 148 PM CDT Tue May 25 2021
** Re: storm potential this afternoon and eve **
This afternoon convective initiation continues to be somewhat murky.
Latest trends in the 18-19Z GOES satellite Day Cloud Distinction
show an area of very weak cumulus development in southeast MN and wc
WI near KONA /Winona/ and northeast. This is along the building SW-
NE CAPE pool of ~1500 J/KG all well out ahead of the surface
dryline/cold front in MN. Cumulus was building and partially
glaciating trying to initiate, but has trended down in the last 30
mins. This matches well with a weaker but steady- state deeper but
broad moisture convergence region extending from the ongoing
convective echo east of Medford, WI, to Winona MN to Mason City per
SPC mesoa page. Day Cloud Distinction also showing growing cumulus
along several frontal/near frontal boundaries across NW WI and
eastern MN...roughly I-35 in MN KAEL- KMSP-KDLH.
Wind shear across the area has increased with 0-6km bulk shear
~40kts or more north of I-90 per RAP and GOES derived cloud motion
winds. Thus, supercell modes will be favored, and with storm motion
45-90 degs to front, should see discrete cells for a period after
initiation.
With aforementioned deeper weak convergence north and just west of
La Crosse, would think lower-end storms could occur as capping is
minimal, but thinking is that this area would have a lower threat of
severe storms due to less sustained convergence. The cold front, now
located further west along the growing cumulus fine lines near I-35
will continue east and provide a late afternoon severe storm threat
in western WI, far southeastern MN /matches western edge of SPC SLGT
risk well/. Would think the frontal convergence and dewpoint
gradient will sharpen a bit in the coming hours, a bit steeper lapse
rates and more large scale lift with shortwave trough energy will
shift in. Overall, the frontal convergence is not super impressive
with broad rounded trough at the surface. This will impact storm
coverage.
Parameters marking the I-90 and north area well for large hail and
wind potential. Large hail parms suggest 2" hail possible there.
Hodographs per current 88Ds at KMPX/KARX are straight line from 0-
2km and RAP hodos still carry small curvature in the 0-1/0-3km
layer. SPC Mesoa Sig Tor Parameter ~1 north of I-90 which confirms a
lower, entry level tornado risk currently. This may grow to ~2 with
a bit of backing, should it occur, which is more likely north of I-
94 later. Thus, hail and wind threats seem on target for our
messaging. Further south of I-90 the shear decreases but is still
favorable for severe storms - just marginal supercellular -
multicellular more favored...early eve timing.
.SHORT TERM...(Wednesday and Friday)
Issued at 215 PM CDT Tue May 25 2021
WET THU/THU NIGHT: Another shortwave is progged to move due east
from the PAC NW tonight, spinning across the upper mississippi river
valley thu/thu night. Some ripples in the flow could kick out of the
trough over the desert SW, preceding the NW shortwave across the
region. 30-40 kt 850 mb jet to feed the system. The mix of
lift/moisture should lead to a broad expanse of rain. Little if any
instability to work with, so thunder threat looks limited at this
time. In addition, while the low level moisture transport noses into
the region, warm cloud depths only peak around 3500 m while sfc pws
top out around 1 1/4". Should see decent rainfall with 1/2 to 1" or
so, but potential for more than a good soaker (ie, flooding
concerns) looks low.
TEMPS: with the passage of the dry line/cold front tonight, colder
air starts to filter in from the north, with the main push of cold
air coming in Thu/Fri. Widespread rain/clouds will also work to keep
temps unseasonably cool. Highs still looking like they will struggle
into the 50s both those days - a marked contrast from recent days
when lows bottomed out in the 60s.
.LONG TERM...(Saturday through Tuesday)
Issued at 215 PM CDT Tue May 25 2021
The GFS and EC both favor shortwave upper level ridging come Friday,
quickly sliding east/flattening that ridge out with west-east
running shortwave across southern Canada. Uncertain whether that
shortwave will sparking any pcpn sat night/early sun. Not much qpf
in the models, and still have an exiting sfc high to contend with.
A better shot for rain could come on Memorial day with some
agreement between the GFS and EC with a piece of upper level energy
dropping out of southern Canada and across the region. The GFS
doubles up with advancing more shortwave energy into the area, out
of a trough over the desert SW. Likely a lingering sfc front will
come into play too. The EC leans more on a split flow type
evolution, keeping more of its qpf across the north and south. The
more robust GFS is widespread with its chances. Several of the EC
ensemble members mimic the GFS`s take though, with bulk of the GEFS
members also siding toward good chances to get wet.
The cool temperatures will persist, although show some (meager)
warming as we push into the new work week. Could see a return to at
or above normal temps by the following weekend.
&&
.SHORT TERM...(Wednesday and Friday)
Issued at 215 PM CDT Tue May 25 2021
WET THU/THU NIGHT: Another shortwave is progged to move due east
from the PAC NW tonight, spinning across the upper mississippi river
valley thu/thu night. Some ripples in the flow could kick out of the
trough over the desert SW, preceding the NW shortwave across the
region. 30-40 kt 850 mb jet to feed the system. The mix of
lift/moisture should lead to a broad expanse of rain. Little if any
instability to work with, so thunder threat looks limited at this
time. In addition, while the low level moisture transport noses into
the region, warm cloud depths only peak around 3500 m while sfc pws
top out around 1 1/4". Should see decent rainfall with 1/2 to 1" or
so, but potential for more than a good soaker (ie, flooding
concerns) looks low.
TEMPS: with the passage of the dry line/cold front tonight, colder
air starts to filter in from the north, with the main push of cold
air coming in Thu/Fri. Widespread rain/clouds will also work to keep
temps unseasonably cool. Highs still looking like they will struggle
into the 50s both those days - a marked contrast from recent days
when lows bottomed out in the 60s.
.LONG TERM...(Saturday through Tuesday)
Issued at 215 PM CDT Tue May 25 2021
The GFS and EC both favor shortwave upper level ridging come Friday,
quickly sliding east/flattening that ridge out with west-east
running shortwave across southern Canada. Uncertain whether that
shortwave will sparking any pcpn sat night/early sun. Not much qpf
in the models, and still have an exiting sfc high to contend with.
A better shot for rain could come on Memorial day with some
agreement between the GFS and EC with a piece of upper level energy
dropping out of southern Canada and across the region. The GFS
doubles up with advancing more shortwave energy into the area, out
of a trough over the desert SW. Likely a lingering sfc front will
come into play too. The EC leans more on a split flow type
evolution, keeping more of its qpf across the north and south. The
more robust GFS is widespread with its chances. Several of the EC
ensemble members mimic the GFS`s take though, with bulk of the GEFS
members also siding toward good chances to get wet.
The cool temperatures will persist, although show some (meager)
warming as we push into the new work week. Could see a return to at
or above normal temps by the following weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1050 PM CDT Tue May 25 2021
Drier and cooler air is pushing into the region with northwest
winds 9 to 15kts with some stronger gusts early on. Decreasing
clouds overnight, however Wednesday morning should see clouds
return to the area. MVFR ceilings are prevalent upstream, but
there are hints that these will become more VFR through the
morning, then decreasing during the afternoon. Northwest winds to
gust 20 to 25kts after 12Z will a reinforcing cool front.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
IA...None.
&&
$$
UPDATE...Baumgardt
SHORT TERM...Rieck
LONG TERM....Rieck
AVIATION...Zapotocny
Area Forecast Discussion
National Weather Service Bismarck ND
909 PM CDT Tue May 25 2021
.UPDATE...
Issued at 907 PM CDT Tue May 25 2021
For this update, tweaked hourly temperatures and the sky cover
forecast through early tomorrow afternoon. Clouds will continue to
diminish across the southwest tonight with temperatures falling
into the mid 30s. Therefore, some patchy frost isn`t out of the
question across the southwest. However, the potential is not
expected to be widespread enough to warrant headlines at the time.
Otherwise, just blended in the latest observations to the
forecast.
UPDATE Issued at 641 PM CDT Tue May 25 2021
Will go ahead and cancel the Wind Advisory with this update. winds
have fallen below criteria over the area. However, it will remain
fairly breezy over the next few hours. Otherwise, just blended in
the latest observations to the going forecast.
A few showers will continue across portions of the south central
and into the James River Valley over the next couple of hours, but
will also diminish with the loss of daytime heating.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 333 PM CDT Tue May 25 2021
Winds diminishing this evening and a frost potential Wednesday
morning highlights the short term forecast period.
This afternoon, a potent mid-level circulation was evident on
water vapor imagery tracking east across the International Border
of North Dakota. Cold air advection at 850-700 mb has created
weak instability, responsible for scattered showers across
northern portions of the state. A tight pressure gradient and
around 40 kts at 850mb have created windy conditions as well, with
wind gusts reaching around 50 mph and sustained winds of 30 to
near 40 mph.
Tonight, the mid-level low will exit east and ridging with a
building surface high will feature in the western portion of the
state. 850mb temperatures will be seasonably cold, falling to the
10th percentile in the NAEFS climatological guidance. This cold
air mass will create a threat of near freezing temperatures, with
a frost or even freeze potential. However this should be generally
mitigated by cloud cover, with RAP guidance depicting high
relative humidity in the 925-850mb layer across the forecast area.
The best opportunity for lows to approach freezing Wednesday
morning may be in the western third of the state where the surface
high will build, again highly dependent on cloud cover. No
headlines will be issued at this time given high uncertainty but
the potential may be there for those with sensitive vegetation to
take precautions anyway.
Ridging and a seasonably cool high pressure center will feature
across western and central North Dakota Wednesday. Highs in the
50s can be expected and weaker winds than today, though the
southwest will be breezy due to a deepening surface low ahead of
the next shortwave trough. Chances for showers will develop in
the southwest ahead of the trough during the day Wednesday, though
best chances arrive Wednesday night.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 333 PM CDT Tue May 25 2021
Good chances for rain across southern North Dakota Wednesday
through Thursday and potentially near freezing temperatures
Thursday morning and Friday morning highlight the long term
forecast period.
Aforementioned shortwave trough is expected to begin to cross the
Dakotas Wednesday and track out of the region Thursday night. The
placement of the lower level baroclinic zone is fairly consistent
model to model favoring rain chances from the ND/SD border to the
I-94 corridor, with the 12Z GEFS members still favoring a
slightly further north solution than the ECMWF ensemble. This
remains consistent with the previous forecast shift, with highest
POPs along and south of I-94 and slight chances up to Highway 2.
The warm sector and associated instability should be well to the
south, with no severe weather in North Dakota expected.
Freezing temperatures will be possible north of the precipitation
shield Thursday morning and then again but more widespread Friday
morning with the lingering cold lower level air mass. The northern
extent of cloud cover Thursday morning will be in question for
freeze potential, but NBM probabilities are at least highlighting
the northern tier of counties as the most likely to fall below
freezing. The strongest probabilities of below 32 F lows are
lower on Friday morning, but the overall potential of frost is
still more widespread with high pressure expected to build.
Temperatures warm back up this weekend with overall mid-level
heights on the rise. A quick moving trough and front will bring a
chance of rain Friday night and Saturday but a notable cool down
is not expected.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 641 PM CDT Tue May 25 2021
Scattered to broken cumulus and isolated showers will diminish as
we approach sunset. However, MVFR ceilings will continue to push
in from north to south tonight and through the overnight hours.
Breezy northwest to north winds will also diminish around and
after sunset. Ceilings will begin to improve into VFR categories
Thursday afternoon, but chances of rain showers will be on the
increase by the afternoon hours across the southwest, mostly
likely impacting KDIK towards the end of the period.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ZH
SHORT TERM...AE
LONG TERM...AE
AVIATION...ZH
Area Forecast Discussion
National Weather Service Denver/Boulder CO
908 PM MDT Tue May 25 2021
.UPDATE...
Issued at 907 PM MDT Tue May 25 2021
Added low PoPs for the rest of the evening and into the early
morning hours. A couple of showers and a weak storm have formed
northeast of Denver. Warm air advection and the left exit region
of the jet appear to be helping this form. HRRR model favor areas
along the north of I-76. Based on satellite and current storm
motion, this appears on track.
UPDATE Issued at 834 PM MDT Tue May 25 2021
IR satellite imagery showing a large batch of high clouds over
the Great Basin. These clouds will track east and over the region
for Wednesday. Appears these high clouds will arrive prior to
sunrise and unfortunately in time for the lunar eclipse. May be
some breaks in the high clouds, or they may be thin enough to
observe the eclipse. Adjusted sky cover grids to reflect this.
Also increased south/southeast winds south and east of Denver
where they should gust to 25 mph at times tonight. Because of this
also increased temperatures a little as well.
&&
.SHORT TERM...(This evening through Wednesday)
Issued at 157 PM MDT Tue May 25 2021
Weak upper level shortwave ridging early tonight shifts east and
gives way to a northern stream shortwave trough moving out of the
Pacific NW and extending south into the Great Basin on Wednesday.
Skies start off clear overnight with light east wind, turning more
south as the surface high shifts east and in advance of the
approaching shortwave. With low RH, clear skies, and light winds
temps to radiate down to just above seasonal normals.
All eyes turn to the skies toward morning when the lunar eclipse
is scheduled. Cloud forecast for optimal viewing is tricky, and
thinking is the urban I-25 corridor into Park County is the best,
although not optimal. In that area there is still the risk for
high cirrus, which could enhance visual impact if thin, or nearly
obscure. Model soundings are not totally saturated above 400 mb,
or roughly 15K feet, so hopefully will be some viewing
opportunities. Further NW into North and Middle Park, closer to
the approaching trough and upper jet should be more clouds. On the
plains, returning moisture on south winds will likely generate
lower clouds. There should be some breaks in the clouds on the
plains, but not totally clear.
For Wednesday return flow sets up on much of the plains, with
gusty southerly winds increasing moisture. Precipitable water
values near .90 inch in the northeast near the 90th percentile for
this time of year. Over the metro area a weak Denver Cyclone sets
up in the morning then dissipates with mixing later in the day.
Max temps forecast upper 70s to upper 80s, with surface based
capes increasing to over 2500 j/kg along an eastern Weld to Akron
to Cheyenne Wells axis, shifting east during the afternoon. By the
afternoon 0-3 km bulk shear gets to 20-30kts in northeast
Colorado. Meanwhile a 60-70 kt 300 mb jet ahead of the approaching
trough will move across the region. All this good for a slight
risk for Wednesday afternoon in far NE Colorado, mainly Sedgwick &
Phillips Counties. High resolution models showing storm initiation
in the eastern Weld & Morgan County area 2-3 pm and move east
through the afternoon.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 157 PM MDT Tue May 25 2021
A few storms may linger into tomorrow evening across our far
northeast. Severe potential would continue as these storms move
off to the east into Nebraska/Kansas. Storm threat should end by
about 9PM or so with the forecast area remaining dry for the
overnight hours.
Thursday will be mostly dry across the area with temperatures a
few degrees cooler than Wednesday. Forecast guidance suggests some
potential for thunderstorms across the southern Foothills/Front
Range mountains but capping overhead should limit coverage.
Maintained some slight chance/chance PoPs for these areas and into
the Denver metro. Warmer temperatures are expected Friday with
southwesterly flow aloft increasing and mid-level temperatures
warming. Highs should reach the low 80s across the plains. The
afternoon should remain dry with just a few showers or
thunderstorms over the higher terrain.
A more unsettled pattern will re-develop this weekend as a slow
moving trough works its way across the desert southwest. Guidance
remains in relatively good agreement in the overall setup, with
weak upslope flow aloft above with near-surface moisture transport
from the Gulf of Mexico. At least a few showers and storms are
possible Friday, but the better moisture and upper level support
comes Saturday through Monday. GFS/ECM both show CAPE > 1000 J/kg
Saturday and Sunday afternoon with well above normal PWATs.
Although there could be a weak capping inversion aloft, the
current forecast is relatively unchanged from the previous
forecast, with chance/likely PoPs over the Front Range and into
the plains from Saturday through Monday. Additional details
regarding burn area concerns detailed in the hydro section below.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 834 PM MDT Tue May 25 2021
VFR conditions to prevail through Wednesday. High clouds increase
tonight with bkn-ovc skies for Wednesday. South to southeast
winds are expected to persist through tonight and Wednesday
morning. Gusts may be as high as 25 knots. Scattered showers and
thunderstorms are expected to form east of the Denver area
Wednesday afternoon. Outflow from this activity may produce a wind
shift or two after 20Z Wednesday.
&&
.FIRE WEATHER...
Issued at 157 PM MDT Tue May 25 2021
Fire weather concerns elevated in the high parks and southern
foothills Wednesday afternoon. Winds will become gusty on the
plains and in the mountains as strong winds aloft mix to surface.
While RH increases on the plains, mountains remain dry.
Jackson/Grand/Summit/Park and southern Jefferson & western Douglas
counties will see minimum RHs in the upper teens/low 20s, with
wind gusts nearing 25 kts. Although below Red Flag criteria, any
fire starts will still move quickly in this environment. Elevated
fire danger will continue across the high parks Thursday and
Friday with continued dry and windy conditions.
&&
.HYDROLOGY...
Issued at 157 PM MDT Tue May 25 2021
No burn area hydro concerns tonight and Wednesday, with no storms
forecast. On the plains, any storms that form Wednesday afternoon
will be heavy rainers in addition to the severe threat, however
storms should keep moving with little flood threat.
The main hydro concern in the forecast period will be this
weekend as a slow moving system provides a few rounds of showers
and storms over most of the forecast area. Storms are expected
each afternoon as weak upslope flow develops Saturday and Sunday.
There should be enough instability over the higher terrain both
Saturday and Sunday for thunderstorms. Above normal moisture over
the area would suggest potential for heavy rains in any
thunderstorms that do develop. Precipitation continues into
Monday, but cooler temperatures would limit thunderstorm
potential. Hydro concerns will decrease Tuesday as the system
departs the region.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Meier
SHORT TERM...Hanson
LONG TERM...Hiris
AVIATION...Meier
FIRE WEATHER...Hanson/Hiris
HYDROLOGY...Hanson/Hiris
Area Forecast Discussion
National Weather Service Quad Cities IA IL
632 PM CDT Tue May 25 2021
...AVIATION UPDATE...
We`re now watching two features which offer thunderstorm
potential. First, a weak vorticity maxima moving through southern
Iowa is increasing coverage of small/narrow updraft driven
thunderstorms in southeast Iowa. These will likely zipper
northeast along and south of a Washington to Maquoketa to
Freeport line this evening. With the updrafts not strong and
appearing to be narrow, they are not expected to become
strong/severe.
The cold front will approach late this evening, with another
better forced, but less CAPE supported round of storms. We`ll have
plenty of moisture, so heavy rains, though spotty, may be over 1
inch. These storms should end by 3-4 AM, and dry weather will move
in for the morning.
ERVIN
.SYNOPSIS...
Issued at 328 PM CDT Tue May 25 2021
Convection burgeoning across portions of southeast Iowa, northeast
Missouri and west central Illinois attendant to a weak upper wave
and divergence. This area has seen an earlier bout of showers,
which coupled with cloudiness has resulted in cooler temperatures
into the lower to mid 70s, overall limiting BL instability in
an area of DCAPE minimum and weaker lapse rates per RAP mesoanalysis.
Elsewhere, extent of convective development in the short term is
a bit murky due to cloudiness limiting temperatures to near the
convective temperature and lack of any coherent boundary, but
there does appear to be a wave approaching from southwest Iowa.
Thus, potential for additional scattered development north/west
is possible rest of this afternoon. Otherwise, it`s been a
breezy/windy day at times with 40 kts LLJ and deeper mixing
leading to gusts 25-35 mph ahead of a surface cold front moving
through far northwest Iowa.
&&
.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 328 PM CDT Tue May 25 2021
Chance of showers and storms will persist tonight until the
cold front passes 08z through 14z from northwest to southeast.
A few of the storms could contain small hail, and also gusty
winds as the BL remains mixed ahead of the cold front. In
addition localized heavy rain is possible with PWATs approaching
1.7 inches. This activity looks to exit around daybreak or
shortly thereafter across the far southeast on Wednesday with
the front departing. In it`s wake, a very nice day is on tap
Wednesday with much less humidity and a northerly breeze along
with abundant sunshine. Highs should top out well into the 70s
and lower 80s.
.LONG TERM...(Wednesday Night through Tuesday)
ISSUED AT 328 PM CDT Tue May 25 2021
Key messages:
1) Potential for MCS and heavy rain Thursday
2) Chilly to end the week, then a pleasant upcoming holiday weekend.
Models remain in decent agreement on bringing an MCS across the
area on Thursday. However, confidence is lower despite the good
model agreement, as some of the old rules of thumb for genesis and
track of MCS`s including 850 mb temperature gradient 19-24c
would support a track well to our southwest/south if surface based
and being in closer proximity to warm front. That said for now
we`re in a marginal risk from SPC in our southern counties which
if complex tracks further north couldn`t rule out some stronger
storms south. The main concern though would be heavy rain with PWATs
over 1.5 inches supporting 1-2 inch rain potential, but again this
pending track/strength of system. Again if system tracks further
south/southwest, then likely still inline for some rain Thursday
with mid level wave and front, but potentially more stratiform rain
and perhaps not quite as widespread or heavy though making for a
nasty day and rather cool.
Following this system, an anomalously strong high pressure system
and cool airmass settles in for late week into the upcoming
holiday weekend. Several models show 850 mb temperatures of 1 to 2C
by 12z Friday! This will result in unseasonably cool conditions
Friday into Saturday, with temperatures 15-25 degrees below normal
with lows mainly in the 40s and highs in the 60s... though on
Friday could see a few 30s for lows far north and highs staying in
the 50s along the Hwy 20 corridor! Should be dry for much if not
all of the holiday weekend, though have kept some small chances by
late in the weekend and for Memorial Day west of the Mississippi
but recent drying trends may see these go away in later forecasts.
It would appear as though any rain chances would wait until return
flow/warm advection commences heading past the Memorial Holiday
into the middle of next week, with highs moderating back near normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
ISSUED AT 621 PM CDT Tue May 25 2021
Brief MVFR cigs are possible this evening, in scattered showers
and thunderstorms. A cold front will arrive overnight, resulting
in winds changing to northwest, and dry air moving in for the
early morning hours. Wednesday appears dry, with VFR conditions
lasting through the day.
Any storm tonight could bring a short period of gusty winds to 40
mph, and heavy downpours. They are enough of a threat for a
temporary condition from 2-6Z or so, but will leave the IFR out of
it for now, until locations can be better determined.
ERVIN
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...05
SHORT TERM...05
LONG TERM...05
AVIATION...Ervin
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
920 PM CDT Tue May 25 2021
.UPDATE...
Convective activity to the west of the CWA, across the Big Bend and
Trans Pecos, has been waning. The 00Z DRT sounding shows a cap in
place at 850mb and SPC mesoanalysis indicates increasing CIN along
the Rio Grande. Latest HRRR runs continue to show no convection
reaching the western CWA. We have elected to remove precip out west
tonight. Elsewhere, a few stray showers are possible through midnight
near the I-35 corridor, as noted by recent but brief activity in
Williamson County.
&&
.PREV DISCUSSION... /ISSUED 653 PM CDT Tue May 25 2021/
AVIATION (00Z TAFs)...
VFR conditions currently prevail across South Central Texas. A few
isolated SHRAs are possible through sunset near and east of the I-35
corridor. We are watching closely convection across West Texas and
the Big Bend. At this time confidence in it reaching DRT is too low
to include in the TAF. Stratus is expected to develop west to east
late evening through the overnight, with mainly MVFR ceilings. A few
pockets of IFR ceilings are possible near and northwest of SAT.
PREV DISCUSSION... /ISSUED 607 PM CDT Tue May 25 2021/
UPDATE...
We have cancelled the Flash Flood Watch for the southeastern
counties. A few isolated showers are still possible through sunset,
but there is no longer a threat for heavy rainfall across this area.
Confidence is decreasing on convection west of the CWA making it into
Val Verde County based on current radar trends and storm motions.
Latest HRRR runs are not indicating convection makes it. For now will
keep a low 20 PoP in the forecast this evening out west and reassess
after sunset.
PREV DISCUSSION... /ISSUED 204 PM CDT Tue May 25 2021/
SHORT TERM (Tonight through Wednesday Night)...
Robust showers and a few storms moving up the Coastal Prairies will
send an outflow boundary northward to collide with the weakening MCS
over Central TX this afternoon. High PoPs and heavy downpours of 1-3
inches are possible with the counties in the watch still the most
likely to see flooding due to the rains of the past 3 days.
Differential heating west of the rain areas should send a brief wave
NW toward the SAT area, but otherwise the rain chances on the lower
part of the I-35 corridor are on their way down. HREF members are
all painting some dry-line convection over W TX moving east into our
western counties in the evening, but with poor agreement on the
extent of influence into our areas. Will show mainly 20-30 PoPs for
Val Verde county and show the activity dissipating just after
midnight over the southern Hill Country. Little of the eastern
activity is expected to last much past sundown, so the FFA should be
allowed to expire by 00Z.
The clouds should remain abundant overnight with muggy morning lows
for Wednesday. Then for daytime Wednesday shortwave ridging over TX
should allow the clouds to mix out with western and central counties
returning back to near normal high temps. Farther east lingering
higher pwat values and ground moisture will keep Max Temps just
below normal and generate a few afternoon pockets of convection.
Humidity and clouds will return another warm low for Thursday
morning, and it looks like the mild overnight lows seen in much of
the spring aren`t coming back anytime soon.
LONG TERM (Thursday through Tuesday)...
Thursday will be a good day for our eastern counties to start to
recover from the multiple rounds of rain over the past several days.
Mid to upper ridging will continue building and helping to dry out
and warm up the area. Thursday`s highs will stay seasonal in the
upper 80s to low 90s. Similar conditions expected for Friday
afternoon, but with a deepening trough to our north, low POPs for
the Hill Country come back to the forecast friday evening and
Saturday. The trough and associated cold front approach the area
Saturday with varying solutions of frontal placement. The front
placement will be the focus for lift for convection and confidence
remains low. The current forecast will maintain the 20-30 percent
chances for showers and storms for that timeframe. Sunday into next
week to remain mostly dry with near normal temperatures.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 71 86 71 87 72 / 10 10 0 - -
Austin Bergstrom Intl Airport 71 86 70 87 72 / 10 20 0 - -
New Braunfels Muni Airport 72 88 72 90 73 / 10 10 0 0 -
Burnet Muni Airport 70 85 70 86 72 / 10 10 0 0 -
Del Rio Intl Airport 75 93 74 95 75 / 10 0 0 0 10
Georgetown Muni Airport 70 85 70 86 72 / 10 10 0 0 -
Hondo Muni Airport 71 89 71 90 72 / 10 - 0 0 -
San Marcos Muni Airport 70 87 71 88 72 / 10 20 0 0 -
La Grange - Fayette Regional 73 88 73 88 74 / 10 30 0 - 0
San Antonio Intl Airport 72 88 72 88 73 / 10 10 0 0 -
Stinson Muni Airport 73 89 73 90 74 / 10 10 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...Runyen
Long-Term...Morris
Area Forecast Discussion...CORRECTED
National Weather Service Grand Rapids MI
1051 PM EDT Tue May 25 2021
LATEST UPDATE...
Update/Marine
Corrected section times
.SYNOPSIS...
Issued at 329 PM EDT Tue May 25 2021
- Showers and Thunderstorms tonight into early Wednesday
- Dry Wednesday afternoon into late Thursday
- Rain, chilly and breezy Friday
- Cool by Dry Memorial Day Weekend
&&
.UPDATE...
Issued at 1051 PM EDT Tue May 25 2021
Cold front is still forecast to bend into the CWA from the west
late tonight and Wednesday morning. A band of rain will push in
associated with the front, but from some left over showers and
storms in the warm sector as well. Most areas will see rainfall
tonight, with totals likely ranging from a quarter to half inch.
Locally heavier swaths of half to three quarters of an inch are
possible as well.
With regard to thunderstorms, the prospects are not great given
the fact that we appreciably lose CAPE as we progress through the
night. There is still more than adequate moisture in place and a
front will be advancing into it, but not expecting much more than
some embedded thunderstorms. Thinking likely rain showers with
scattered thunderstorms is the way to go tonight. Threat of severe
storms is pretty much nil, but if we were going to see anything
strong it would be up towards Big and Little Sable Points in the
midnight to 500am time frame. Marginally gusty winds would be the
main threat.
&&
.DISCUSSION...(This evening through next Tuesday)
Issued at 329 PM EDT Tue May 25 2021
- Showers and Thunderstorms tonight into early Wednesday-
We are expecting an area of showers and thunderstorms to track
into Southwest Michigan around midnight, then weaken as they move
east through the I-69 area by sunrise. Expect locally heavy
rainfall near and west of US-131, mostly near and north of I-96.
There is some suggestion the I-69 area may get locally heavy rain
as there is better coupling of the upper divergence with the
surface wind convergence.
The upper low that was stalled over the Southwest CONUS this past
weekend is shearing out over the top of the eastern CONUS upper
ridge tonight. This puts southwest Michigan in the jet entrance
region of a 125 knot jet core. Typically this would mean strong to
severe storms however as it turns out the low level jet core will
be ahead of the convection tonight. On the other hand the deep
layered shear is between 30 and 40 knots tonight. The precipitable
water is around 1.5 inches. The most unstable cape will be near
1000 j/kg as the storms move into Southwest Michigan late this
evening but that falls quickly to below 500 j/kg by 3-4 am. In
fact the MU cape really never gets over 300 j/kg south and east of
Grand Rapids overnight.
Putting this together, and the HRRR for every run since at least
06z continues to show this as does the HREF, an area of showers
and thunderstorms will move into lake shore, north of Muskegon by
midnight. That will be when the storms are the strongest. As the
storms move on shore they will weaken. The as the line moves south
and east the part of the line west of US-131 will stay strongest
but even that will be weakening over time. It may well be
locations south and east of Grand Rapids will not even see
thunderstorms. Most of the area should get at least some rain.
Isolated locations may get more than an inch of rain tonight but
most areas should get at least a tenth of an inch.
The instability increases once the sun comes back up Wednesday
but by then the storms should be east of here. The bottom line is
the most impactful storms are expected to be near and west of
US-131, north of I-96. There gusty winds, frequent cloud to ground
lighting and locally heavy rain are the most likely impacts.
- Dry Wednesday afternoon into late Thursday-
Once the cold front comes through, we get on the anticyclonic
side of the upper jet. Tandem with that, surface high pressure
moves in to the area. The center of the high is over central
Canada but the ridge axis of the surface high crosses Michigan on
Thursday. This will be bring in much cooler and drier air too.
Highs will be in the 70s tomorrow and only the 60s Thursday.
Patchy frost is possible up north Thursday morning.
- Rain , chilly and breezy Friday-
Upstream we have another shearing out upper low. We have had many
of these this year and so far nearly all of them have brought
rainfall (snowfall when it was cold enough) south of this area.
However, this time it is looking a little better for the rain to
be farther north and actually impacting this area. This will help
mitigate some of the drought impacts too. There is good model
consensus for this area to get between .25 and a half inch of
rain. With the surface low tracking south of here Friday will be
chilly and breezy day. It may well be if we really get this rain
all day, temperatures will mostly be in the 40s! The rain should
come to an end by mid evening Friday.
- Cool by Dry Memorial Day Weekend-
Once that system moves out we get a shortwave ridge for Saturday
into Sunday. A system tracks well north of here Sunday into Monday
but at point it looks dry into Monday. There is a significant
threat for frost Saturday morning and Sunday morning. Areas near
and north of route 20 and east of US-131 may even have a freeze
for a few hours both nights.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 809 PM EDT Tue May 25 2021
A cold front will sag southeast through the TAF sites tonight into
Wednesday morning. A band of rain will move through the TAF sites
along and ahead of the front moving through our area between
midnight and noon EDT. Some embedded thunderstorms are possible,
but instability will be waning and fairly low overall as we head
through the night. An area of MVFR ceilings will develop overnight
and persist into Wednesday morning. The MVFR conditions will show
up at MKG around 07z and exit the southeast at JXN around 17z.
Visibilities should not dip much below MVFR as the showers move
through. VFR conditions are expected Wednesday afternoon. Winds
will shift from the southwest tonight to west Wednesday midday and
eventually northwest Wednesday afternoon and evening.
&&
.MARINE...
Issued at 1051 PM EDT Tue May 25 2021
Considered dropping the entire Small Craft Advisory as the warm
air advection winds are having a hard time mixing to the lake
surface. We did drop out the southern 3 zones as the winds and
waves are just not meeting criteria. The Ludington buoy has been
showing 4 footers for a time, so decided to leave the SCA going
for the northern three zones. Even here though, it may be confined
to the far north, north of Little Sable Point.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 8 AM EDT Wednesday for LMZ847>849.
&&
$$
UPDATE...DUKE
SYNOPSIS...WDM
DISCUSSION...WDM
AVIATION...DUKE
MARINE...DUKE
Area Forecast Discussion
National Weather Service Wichita KS
853 PM CDT Tue May 25 2021
...Evening Mesoscale Discussion...
.MESOSCALE DISCUSSION...
Issued at 851 PM CDT Tue May 25 2021
BOTTOM LINE UP FRONT: We continue to monitor south-central Kansas
for possible thunderstorm development this evening, but the
potential appears more conditional. If storms do, indeed, manage to
develop, severe weather would be possible.
DISCUSSION
As of 01z/8pm, satellite and surface observations pointed towards a
weak surface low near Dodge City. A stationary frontal boundary
extends southwest into the OK/TX Panhandles. To the north, a cold
front stretches from the western Great Lakes southwest into central
KS, where it intersects the above-mentioned SFC low. There also
appears to be a weak surface boundary that stretches NW to SE from
KS into central OK (perhaps a feature leftover from earlier day
convection?).
Scattered convection continues ahead of the Great Lakes to KS cold
front, with the southern end of that convection showing a weakening
trend recently on radar (south of Salina). Meanwhile, the last of
the visible satellite images reveal some towering CU/convective
attempts where convergence is maximized near the SFC low. More
robust convection is ongoing further southwest across the TX/OK
Panhandles. Recent RAP analysis suggests inhibition is still fairly
weak across southwest/south-central KS, but a lack of stronger low-
level convergence/large-scale forcing appears to be limiting
storms from getting going near the SFC low. We`ll continue to
monitor this area as a weak LLJ develops north from the TX
Panhandle into SW KS. Short term guidance hints at some continued
risk of storms near/just east of the SW KS SFC low, but this
potential seems more conditional given the above-mentioned lack of
lift. If storms can develop, and be sustained through tonight,
severe weather would be possible. But, again, this threat appears
very conditional.
Martin
&&
.SHORT TERM...(This evening through Thursday night)
Issued at 312 PM CDT Tue May 25 2021
The main forecast concern is the potential for severe weather
later Wednesday night and especially Thursday.
Will maintain scattered thunderstorms in the forecast for tonight
with the surface-850 trough axis moving slowly southeastward across
eastern/southern Kansas.
For Wednesday, south-southeasterly return flow will occur across the
central Plains as an upstream shortwave trough progresses from the
Great Basin/Northern Intermountain region into the Rockies. Mid-
level shortwave ridging and associated weak subsidence should act
as a suppressor to convection in the forecast area. Moist upslope
flow and quasi-geostrophic forcing associated with the
approaching shortwave trough will allow convection to develop over
the northern/central High Plains Wednesday afternoon/evening. Any
convection further southward along the dryline would likely be
isolated with warmer mid-level temperatures. As a 50 knot
southerly low-level jet develops Wednesday evening, the severe
storms coming off the northern/central High Plains should grow
upscale into MCS clusters which will propagate east-southeastward
across Nebraska and especially northern Kansas. Will have likely
storm chances roughly along/north of Interstate 70, tapering
probabilities further south to 30%. These storms could contain
strong-severe wind gusts and locally heavy rainfall.
Thursday-Thursday night: This period looks to have the highest
severe weather potential in the forecast area. The shortwave trough
will continue moving east across the northern Plains, allowing a
slow-moving cold front to work southeastward across eastern/southern
Kansas. There is also a decent chance that an outflow boundary from
overnight MCS activity could be located somewhere across eastern
Kansas which could become a wildcard factor depending on how far
south it makes it. Highs in the mid-upper 80s and dewpoints of
65-70 degrees will be in place ahead of the front around peak
heating. Very strong to extreme instability is progged with
moderate deep-layer shear. Surface-based storms should develop by
early-mid afternoon from central Kansas southwestward into south-
central Kansas. A combination of multi-cell and supercell
structures is likely during the afternoon hours, with very large
hail possible and damaging winds. A tornado or two cannot be ruled
out near any effective residual outflow boundary, and along the
northeast-southwest oriented cold front given the extreme
instability and respectable low-level CAPE. A transition to a
linear MCS storm mode is expected across southeastern Kansas
Thursday evening as the cold front moves through. As a result,
the threats should evolve to primarily damaging winds, isolated
large hail, and locally very heavy rainfall.
.LONG TERM...(Friday through Tuesday)
Issued at 312 PM CDT Tue May 25 2021
Cooler than normal and drier air will infiltrate Kansas from
Friday into this weekend as the cold front pushes southward to the
Gulf. Pleasant weather is expected this weekend in the forecast
area, with any convection chances confined to the High Plains.
Chances for thunderstorms may re-enter the forecast picture early
next week as a positively-tilted upper trough approaches the
central Plains from the western CONUS.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 651 PM CDT Tue May 25 2021
* Isolated TSRA and low CIGs possible through tonight
A couple of surface boundaries moving slowly through the area may
continue to be a focus for isolated to scattered TSRA over the next
12 hours or so, but confidence is too low to for any TEMPO, or
prevailing, TSRA groups in the TAFs. We`ll continue to closely
monitor this potential, though. Where TSRA do occur, gusty/erratic
winds and hail will be possible. On Wednesday, another surface
boundary/warm front is forecast to move north through Kansas. This
boundary may be accompanied by low CIGs and possibly some SHRA/TSRA.
EXTENDED PLANNING OUTLOOK: TSRA will continue to be a potential
impact Wednesday night through Thursday, some of which will likely
be severe.
Martin
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 64 84 69 85 / 30 10 40 70
Hutchinson 61 85 68 85 / 30 10 40 50
Newton 62 83 68 83 / 30 10 40 70
ElDorado 63 83 68 84 / 30 10 40 80
Winfield-KWLD 64 84 69 85 / 20 10 30 80
Russell 58 84 63 82 / 20 10 60 30
Great Bend 59 84 66 83 / 30 10 50 30
Salina 60 86 67 84 / 30 10 60 50
McPherson 60 84 67 83 / 30 10 50 60
Coffeyville 65 82 69 84 / 40 10 30 80
Chanute 65 82 69 83 / 30 10 30 90
Iola 65 82 68 82 / 30 10 30 90
Parsons-KPPF 65 82 69 83 / 40 10 30 90
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
MESOSCALE...RM
SHORT TERM...JMC
LONG TERM...JMC
AVIATION...RM
Area Forecast Discussion
National Weather Service Lincoln IL
804 PM CDT Tue May 25 2021
.SYNOPSIS...
Issued at 134 PM CDT Tue May 25 2021
Scattered showers and thunderstorms will increase in coverage late
tonight as a cold front approaches from the northwest. Then, after
a dry day for most on Wednesday, another chance for widespread
showers and storms arrives Thursday afternoon and into Thursday
night, bringing the potential for strong to severe storms and
torrential rain. Conditions turn cooler and drier for the holiday
weekend.
&&
.UPDATE...
Issued at 804 PM CDT Tue May 25 2021
Not a lot of lightning thus far in our forecast area, though we
did have some strikes earlier around Decatur/Champaign, and some
recent stronger showers have started to form along an outflow
boundary between Decatur and Bloomington. Elsewhere, light showers
have been affecting the Illinois River valley, though with
ceilings pretty high up, not much of substance reaching the
surface. Additional showers are moving northeast out of Missouri
and will affect much of the forecast area later this evening.
Latest surface obs show the main cold front from southwest to
northeast across Iowa, accompanied by clusters of showers and
storms. 6 pm HRRR run brings the front into the Galesburg area
around 4 am and Springfield toward 7-8 am. While the highest PoP`s
will be east of I-55 with the rain currently in Missouri, will
have 40-50% rain chances across the northwest CWA overnight with
the front`s arrival.
Latest zones/grids have been sent.
&&
.SHORT TERM...(This evening through Wednesday)
ISSUED AT 134 PM CDT Tue May 25 2021
Afternoon GOES WV imagery depicts a closed upper-level low
spinning over southern Manitoba. This feature will help drive a
surface cold front through the upper Midwest tonight into
Wednesday.
Scattered light showers have developed west of the Illinois River
this afternoon in response to subtle shortwave energy rippling
through the mid-level flow. Skinny CAPE and poor shear profiles
have limited convective activity up until this point, and that
trend will likely continue through early this evening as quite a
bit of dry air remains in the lowest few kilometers of the
troposphere, further hindering updrafts. Latest CAMs are
suggesting scattered showers staying west of I-55 through this
evening, with a mostly dry forecast for locations east of I-55
given the drier air. However, as the nocturnal LLJ begins to
strengthen and veer into southern Illinois late tonight ahead of
the cold front, more widespread showers and thunderstorms are
anticipated and locations east of I-55 will no longer be spared.
When it`s all said and done, QPF will range between a couple
tenths across most locations and one inch wherever convection
becomes focused overnight, namely south of I-72.
The current placement of the front extends from Minneapolis, MN
to Sioux City, IA to Grand Island, NE. The latest hi-res trends
suggest frontal passage occurs at Peoria by 13z/8am, at Lincoln by
15z/10am, and at Mattoon by 17z/12pm. In its wake, a drier and
slightly less humid air mass will settle into central Illinois for
Wednesday afternoon. Temperatures will still warm into the lower
to middle 80s beneath plenty of sunshine while overnight lows cool
to near 60 degrees.
&&
.LONG TERM...(Thursday through Tuesday)
ISSUED AT 134 PM CDT Tue May 25 2021
The attention quickly shifts to Thursday as a frontal system rides
roughly parallel to the I-70 corridor. By late Thursday
afternoon, portions of southern and central Illinois will be
positioned in a warm sector with a boundary layer characterized by
surface dewpoints in the mid 60s, MLCAPE values between 500-1500
J/kg, and deep layer shear around 40 kts. As the system warm front
slowly lifts northward across the region, backed surface winds
will likely enhance low-level turning and support organized
updrafts. There is still some uncertainty on whether storms will
be surface-based or elevated. The latest BUFKIT soundings reveal
a capping inversion through much of the day, and a potential
decaying MCS earlier that morning may limit solar insolation.
Nevertheless, strong potential instability and mid-level flow will
favor organized storms Thursday evening.
Another concern for Thursday evening will be the potential for
flash flooding. With anomalously high PWATs (progged in the 95th
percentile of climatology) and storm motion roughly parallel to
the frontal boundary, repeated rounds of heavy thunderstorms will
be possible across portions of central Illinois. Latest QPF
guidance from WPC offers 0.75"-1.50" across our outlook region,
but the potential for localized 3.00"+ is certainly a possibility.
Friday through early next week continues to look like a dry
stretch across the Great Lakes and Midwest with mild temperatures
beneath an expansive area of cooler surface high pressure. Daily
temperatures through the holiday weekend will yield afternoon
temperatures in the upper 60s to lower 70s with overnight lows in
the upper 40s to mid 50s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 621 PM CDT Tue May 25 2021
Scattered storms passed near KDEC/KCMI earlier, but much of the
early evening rain activity in central Illinois is devoid of
lightning. Think this will last for a few hours, before
showers/storms move northeast out of Missouri, and have
concentrated the VCTS mention beginning around 03Z, from southwest
to northeast. As a cold front moves into the area overnight, a
period of MVFR ceilings, potentially below 2,000 feet, is
expected for about 5-8 hours. VFR conditions should return by
midday as skies clear behind the front.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Geelhart
SYNOPSIS...MJA
SHORT TERM...MJA
LONG TERM...MJA
AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Indianapolis IN
1158 PM EDT Tue May 25 2021
...Updated Aviation Discussion...
.Forecast Update...
Issued at 936 PM EDT Tue May 25 2021
Surface analysis this evening shows broad high pressure in place
across the southeastern states. A cold front was found across NW
Wisconsin...stretching southwest across Iowa. Water vapor imagery
shows a plume of deep moisture streaming across Missouri into
Illinois and NW Indiana. Skies across Indiana were partly
cloudy...with clouds associated with this plume invading from the
west. Warm and moist southerly surface flow was in place across
Indiana with dew point temps in the 60s.
Clouds will be expected to continue to invade overnight. This along
with ongoing warm air advection will hamper cooling of
temperature. Thus have stuck close to the NBM on lows...trending
several degrees warmer than persistence. HRRR keeps precip east of
the forecast area for the next several hours. However forecast
soundings and time heights begins showing saturation aft 06Z. Thus
have tried to keep to a dry forecast through 06Z...ramping up pops
from west to east thereafter.
&&
.Short Term...(This evening through Wednesday night)
Issued at 336 PM EDT Tue May 25 2021
High pressure is moving off to the SE, over Florida, diminishing
subsidence over the area. Isolated showers have already started to
form across central Indiana. Currently these showers are pulsey
afternoon showers from daytime heating but additional convection and
thunderstorms will be possible later this afternoon. Precipitation
coverage will then increase later this evening into Wednesday as the
trough axis swings across the region. The surface low is
continuing to make its way across Canada and as it tracks just
south of the Hudson Bay tonight into tomorrow, the associated cold
front extending SW into the central plains and Mississippi Valley
will bring a line of isolated to scattered showers to the area.
For tonight, some instability will be present but below 500 J/kg.
Weak frontogenesis and upper lift with the decent amount of moisture
will be enough to produce showers and isolated thunder throughout
the night. Going into Wednesday morning, the front is then expected
to slow down and briefly stall just to the east as the low lifts
north. Models show instability increasing to above 1000 J/kg
Wednesday morning into midday as well as low level lapse rates. This
will then allow for a threat of some gusty winds and possibly
evening some hail to be embedded within storms during the day as
the airmass will still be fairly warm and unstable. At this time,
the area with the best chance of some stronger storms will be
across the SE half of the forecast area.
Weak ridging will establish rather quickly in the wake of the
frontal passage with noticeably drier air advecting in. Should see
clearing skies by late day into the northwest half of the forecast
area with all convection out of central Indiana by midnight with dry
weather expected throughout Wednesday night.
With rain and higher dew points tonight, overnight low temperatures
will only get down to the mid to upper 60s. Above normal
temperatures will continue into tomorrow, albeit slightly cooler
than central Indiana has been seeing this past week. Behind the weak
cold front, tomorrow night`s lows will drop back down to near 60.
&&
.Long Term...(Thursday through Tuesday)
Issued at 336 PM EDT Tue May 25 2021
A short wave trough will approach central Indiana on Thursday,
leading to the main precipitation event for the long term.
During the day on Thursday, weak flow in the low levels will limit
moisture transport resulting in 20 degree dew point depressions.
This will push the LFCs closer to the ML laps rates of less than 7.0
C/km, limiting the overall instability. However, by later that
evening, the short wave trough will near, helping advect warm, moist
air within SW flow. Stronger WAA will keep evening temperatures from
falling, maintaining in the mid 70s with dew points in the upper 60s.
The resulting low LCLs and broad isentropic lift should help
initiate convection out ahead of the trough with likely rain and
scattered thunderstorms after sundown.
There will be a severe threat with this convection late Thursday
evening into Thursday night. The moderate WAA will keep the
thermodynamic environment fairly conducive for longer. CAPE values
around 1000 J/kg are expected to maintain through around 04Z;
, diurnal cooling will begin to take over, limiting any
SBCAPE. Prior to this, the development of a nocturnal LLJ along with
a deepening surface low will create a fairly conducive environment
for isolated severe thunderstorms. Wind will be the primary threat
as by the time the thunderstorms reach central Indiana they should
be primarily linear. The strengthening LLJ and resulting speed shear
should help induce some RIJs within linear segments.
As diurnal cooling takes over, the thunderstorms will become
elevating reducing the wind threat greatly. This is likely to occur
shortly after the 04-06Z time period. The severe threat for the
entire region will greatly depend on when the thunderstorms reach
central Indiana.
After this event passes through early Friday morning, the
thunderstorm threat will drop to near zero, with isolated showers
possible within wrap around moisture. High pressure will begin to
build in the wake of the system helping clear out skies late on
Friday. The resulting high will originate from the colder Canadian
Plains, keeping temperatures much cooler this weekend. Expect highs
in the low to mid 70s with dew points in the low 50s.
The next rain event looks hold off until early next week as SW flow
returns, replacing the high pressure from this weekend.
&&
.Aviation...(06Z TAF Issuance)
Issued at 1158 PM EDT Tue May 25 2021
IMPACTS:
- VFR Conditions overnight.
- MVFR CIGS with SHRA arriving near 12Z Wed.
- A return to VFR aft 18Z-20Z Wed.
DISCUSSION: High pressure was found over the southeastern states. A
plume of tropical moisture was streaming clouds across Missouri to
IL and southern MI. Radar shows areas of scattered showers beneath
this plume to the west. GOES16 show SCT Cu and a few high clouds
across Central Indiana. Showers over IL were making slow progress
northeast. Given this...VFR conditions will be expected the next few
hours as the plume of moisture to the west slowly advances...and sct
precipitation arrives through the night along with a short wave
aloft.
Time heights and forecast soundings show deep saturation
through the morning hours as the HRRR shows scattered showers
drifting across the TAF sites.
As the short wave departs on Wednesday afternoon forecast soundings
and time sections dry out as subsidence begins. Thus a return to VFR.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...Puma
Short Term...KH
Long Term...Updike
Aviation...JP
Area Forecast Discussion
National Weather Service New Orleans LA
937 PM CDT Tue May 25 2021
.EVENING UPDATE...All forecast parameters are on track with
observed conditions and there will be no changes made to the
forecast this evening. PG
&&
.PREV DISCUSSION... /issued 635 PM CDT Tue May 25 2021/
AVIATION (00Z TAF DISCUSSION)...VFR condtions will remain in
place at all of the terminals through around 08z. After 08z,
weak boundary layer flow will allow for another night of patchy
fog at some of the inland terminals. KMCB will be most prone to
fog development and have a TEMPO group with LIFR visibility and
ceiling conditions in place from 10z through 14z. IFR conditions
are forecast with TEMPO groups at KHDC, KBTR, and KASD around 12z.
By 15z, all of the terminals should return to VFR conditions as
boundary layer mixing increases. PG
PREV DISCUSSION... /issued 327 PM CDT Tue May 25 2021/
SHORT TERM (Today through Thursday)...
Quick scan of the upper levels shows a broad ridge draped over
the southeast CONUS and a trough dipping out of Canada into the
upper Mississippi Valley. That trough will skirt the US/Canadian
border as it tracks east Wednesday before heading towards the
northern Atlantic Thursday. A shortwave will be following in the
wake of this trough although a bit farther south latitude-wise.
The track of those 2 troughs will cause the ridge over the
southeast to suppress. This won`t do much in the way of dropping
temps but might allow for some isolated to scattered storms to
develop this afternoon and again on Wednesday. The NBM POP output
looks great and basically mirrors the deterministic HRRR composite
reflectivity. Thus, will be just going with the NBM for coverage
forecast the next few days. Same for the temps, which is
fluctuating above/below climo for this time of year.
MEFFER
LONG TERM (This Weekend)...
The trailing shortwave will be absorbed by the trough in the
northwestern Atlantic. The apex of these combined troughs will
stretch southwest from the northeast CONUS down the Appalachian
Mountains to almost the northern Gulf Coast on Saturday. In doing
so, the ridge thats currently in place over the CWA will be
completely squashed. A boundary associated with the trough will
approach the local area from the north/northeast late in the day on
Saturday. It does have somewhat a of a backdoor front `look`. GFS
sounding at MCB does show modest CAPE. Shear values are quite weak
however. Suspect there will be some potential for some strong and a
few marginally severe storms with hail and gusty winds the main
threats. Either way, this weekend will probably be fairly active
with at least 50% coverage (or more) on Saturday. Sunday will
possibly be just as active too. That is more dependent on if the
boundary stalls or continues south into the open Gulf.
MEFFER
AVIATION...
VFR to MVFR ceilings will persist through the forecast period.
Visible satellite shows CU field has developed over the region. The
height of decks should vary from high end MVFR to low end VFR. These
clouds are diurnal and will fade as the sun set.
MEFFER
MARINE...
Center of a surface ridge will generally remain east of the coastal
waters throughout the week. This will keep onshore flow in place
with gradual variances in wind direction. The same goes for wind
speeds but should stay in the realm of 5-10 and 10-15kts.
MEFFER
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 67 86 67 88 / 10 20 0 10
BTR 68 87 68 88 / 20 30 0 20
ASD 68 86 68 88 / 0 20 0 10
MSY 71 87 71 88 / 10 20 0 10
GPT 70 85 70 85 / 0 10 0 10
PQL 67 85 67 86 / 0 10 0 10
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
913 PM CDT Tue May 25 2021
.UPDATE...
912 PM CDT
Numerous subtle mid-level perturbations pushing across the region
within a moist and generally uncapped airmass have supported
areas of showers and the occasional thunderstorm this evening.
Think the thunder potential in the immediate near term here will
remain low as we await the arrival of the next set of impulses,
one across central Missouri, and then the main shortwave upstream
which is presently pushing into western Wisconsin. With surface
dewpoints in the upper 60s to near 70 degrees across northwest
Illinois, convective inhibition is minimal even at this hour, and
so the anticipation is for a gradual increase in shower and
embedded thunderstorm activity ahead of an incoming cold front
as better jet dynamics overspread our area with time tonight. With
this in mind, we`re thinking the latest runs of the HRRR are a
bit underdone with precipitation chances towards midnight and
thereafter.
The more substantial mid and upper-level flow is forecast to lag
the main area of precipitation a bit, and so while we`ll start to
slightly increase our 850-600 mb lapse rates with time, the
potential for much storm organization seems pretty low. A rogue
storm with a stronger wind gust or small hail can`t be ruled out,
but the strong-severe threat continues to look pretty low.
As 925-850 mb flow increases ahead of the incoming trough, there
may be a brief window favoring some slow-moving/backbuilding
convection before the low-level flow veers more appreciably late
tonight. This window (<3 hours or so) seems too brief to cause any
flooding concerns, especially considering how dry things have been
of late, but some locally heavier rainfall can`t be ruled out
across parts of northwest Illinois.
Carlaw
&&
.SHORT TERM...
245 PM CDT
Through Wednesday night...
Shower and thunderstorm trends/timing into tonight continue to be
the primary focus for the short term period.
The Gulf Moisture plume that has resided to our west-southwest
over the past few days is now being steered east-northeastward
into our area in advance of a robust storm system shifting
eastward across southern Manitoba into western Ontario. The
airmass within this moist plume moving into the area features
precipitable water (PWAT) values in excess of 1.6" (1.65"
measured on the 12 SGF RAOB). While the main storm system will
remain well to our north in southern Canada, an associated cold
front will shift southward towards the area tonight. The
approaching front will set the stage for a period of showers and
thunderstorms across much of the area tonight.
Scattered showers are already ongoing across parts of the area
early this afternoon. This activity is being driven by a smaller
scale perturbation in the mid-level flow. Most of these showers
have been void of lightning primarily due to poor lapse rates
above a well-mixed boundary layer. While this looks to continue
to be the case for the next couple of hours, we cannot rule out a
few thunderstorms late this afternoon. The main threat from these
showers will be some locally gusty winds up to 45 mph.
More widespread showers and thunderstorms are likely over northern
IL and northwestern IN tonight after 10 PM. These storms are
expected to develop to our northwest late this afternoon in the
vicinity of the aforementioned surface cold frontal boundary as
it begins to interact with the higher theta-e pre-frontal airmass
shifting into the region. Upscale growth into a southeastward
moving line/cluster of storms is then likely this evening as
moisture convergence increases along the elevated frontal boundary
beneath the entrance region of a 90+ KT upper jet streak developing
over the Upper Midwest and western Great Lakes. Gusty surface
winds may accompany some of the stronger storms tonight, but the
overall severe threat looks to remain low/isolated. However, some
locally heavy rainfall will be likely with these storms given the
high PWATs. Also, the northeastward movement of the individual
storms could result in a short period favorable for some training
storms along the frontal boundary. While this could result in some
isolated minor hydro concerns, the ongoing drought conditions and
low river levels across much of far northern IL are likely to
limit the threat for flooding outside of urban centers.
The showers and thunderstorms will likely undergo a diurnal
weakening trend overnight, so there is some uncertainty about the
southern reach of these storms late tonight. Any lingering
showers and storms should end from northwest to southeast late
tonight. Quieter weather is on tap for Wednesday following the
frontal passage. Expect highs on Wednesday to be in the lower 80s
for inland areas, with a bit cooler temperatures expected near the
lake due to the likelihood of an afternoon lake breeze.
KJB/Ogorek
&&
.LONG TERM...
245 PM CDT
Thursday through Tuesday...
Low pressure will track eastward across southern Iowa and into
central IL Thursday and Thursday night. This should result in a
pronounced east to northeast low level flow across the area which
should suppress the associated warm frontal boundary well south of
the lake and may hang the boundary up across our southern tier of
counties. Rain chances will spread in from the west as the system
approaches Thursday afternoon into the evening. Greatest thunder
potential will be closer to the warm front over southern sections
of the area. Will need to monitor the threat for severe
thunderstorms near and south of the front and with SPC Day 3
Enhanced risk currently to the southwest. Latest thinking
continues with the idea that most areas will see some rain with
this system but there is always the chance that significant
convection to the south robs some of our moisture flux or provides
some level of subsidence to the local area. Highest amounts will
be focused closer to the front with the better convection with
lighter amounts to the north. Thursday will also see a large
spread in highs from north to south and near Lake Michigan. Expect
upper 50s near the lake with low to mid 60s for northern inland
areas and mid or even upper 70s south of I-80.
The surface low will be to the east on Friday but the associated
upper level trough will cross the area bringing showers to the
area and much cooler air. Northeast winds will be steady with
highs only expected to be in the 50s for most areas, with lower
60s far south.
High pressure will spread into the Great Lakes Saturday and be in
place through the weekend. Temperatures will moderate overall,
but persistent flow off Lake Michigan will keep areas near the
lake cooler each day. Expect 60s Saturday then 70s thereafter
inland of the lake. There are mixed signals for rain chances by
Monday but with variability in guidance collaborated with
neighboring offices to keep the forecast dry during the day with
chances increasing Monday night.
MDB
&&
.AVIATION...
For the 00Z TAFs...
An area of -SHRA associated with a weak mid-level wave will cross
the Chicago metro through 02Z. While TS had been observed
upstream with this activity, the environment has become much less
supportive of TS over the terminals.
A lull in the precip is expected mid evening into the early
overnight hours, though a few stray showers will remain possible.
SW winds will continue to gust to 25kt during this time.
Ongoing convection across central IA and central WI will likely
connect into a broken line of TS through mid-evening. This line
will propagate southeastward across northern IL and northwest IN
during the overnight and pre-dawn hours and may contain wind gusts
in excess of 30 knots. A narrow axis of MVFR ceilings, possibly
as low as 1kft, will likely develop behind the convection through
daybreak Wednesday before the arrival of much drier air behind a
cold front around 12-13Z. VFR conditions are expected through the
day Wednesday with WNW gusts over 20 knots. A lake-enhanced
boundary will then shift winds NE at 10-15 knots early Wednesday
evening at ORD/MDW.
Kluber
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...nearshore waters
until 4 AM Wednesday.
&&
$$
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Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
946 PM CDT Tue May 25 2021
.UPDATE...
Issued at 938 PM CDT Tue May 25 2021
The forecast looks generally on track for the rest of the night
with scattered showers moving through east central and southeast
Missouri into southwest/south central Illinois. Short range
deterministic guidance shows low level moisture convergence over
the region, and this looks like the primary forcing mechanism for
these showers. This moisture convergence shifts east through the
night ahead of an 850mb trough, and it`s through our eastern
counties by around 12-15Z. The RAP is still showing a bit of
MUCAPE over the region...maybe just enough to produce a
thunderstorm or two, so I`ve left slight chance for thunder in the
forecast for the rest of the night.
Carney
&&
.SHORT TERM... (Through Late Wednesday Night)
Issued at 323 PM CDT Tue May 25 2021
Key Messages for the short term period:
1. An MCV system will move north-northeast into the CWA this
afternoon and evening, producing widespread rain over the area.
2. Wednesday afternoon and overnight will be dry.
Showers continue across central and northwest Missouri into west-
central Illinois this afternoon, driven by low-level WAA. While a
couple flashes of lightning have been observed across west-central
and northeast Missouri this afternoon, forcing is too weak to tap
into the 500-1000 J/kg of MUCAPE present across the forecast area.
While spotty WAA showers are anticipated to continue across the CWA
through the evening, the MCV in southeast Missouri is the main
feature of note for this afternoon and evening. Driven by a
shortwave aloft, this complex will move north-northeast into central
Missouri by mid-afternoon and produce widespread showers and a few
thunderstorms. Even though the forcing for this complex is more
robust, the massive cold pool generated by the precipitation is
cutting the system off from environmental instability. Given this,
and that the system will move into the forecast area during the
waning hours of the afternoon, nothing more than a rumble or two of
thunder is expected amid the widespread rain.
A weak baroclinic zone will drop southward through the Northern
Plains and Upper Mississippi Valley during the day today, finally
inching into our forecast area by early Wednesday morning. Showers
and a few thunderstorms could generate along this boundary as it
slides through the region Wednesday morning, enhanced by WAA along
persistent low-level southwesterly flow. Thunderstorm development
will be limited as the weak boundary slides out of the CWA by late
morning, and lapse rates, instability, and shear will be poor. A
deepening surface high over the Great Lakes region will help push
the baroclinic zone through the forecast area tomorrow, providing a
brief dry period Wednesday afternoon through the overnight hours.
The weakness of the surface boundary will result in little change
between today`s high temperatures and tomorrow`s. Today`s noon-time
temperatures across eastern Nebraska and western Iowa, behind this
feature, are in the upper 70s to low 80s. High temperatures
forecasted across the CWA are in the mid 80s, accounting for the
mostly sunny post-feature sky and slightly more southern latitude.
Overnight temperatures tonight and Wednesday will be in the 60s,
though slightly cooler Wednesday night as the mostly clear sky at
the beginning of the night will produce more effective radiational
cooling.
MRM
.LONG TERM... (Thursday through Next Tuesday)
Issued at 323 PM CDT Tue May 25 2021
Key messages for the extended period:
1. There is a potential for strong to severe thunderstorms on
Thursday.
2. Memorial Day weekend will be cool and largely dry.
By early Thursday morning a mid-level trough will be pushing through
the central Plains into the Mid-Mississippi Valley, guiding an MCS
into the region. Operational models are in agreement with the
formation and relative positioning of the mid-level trough and in
the movement of the MCS through the CWA. However, guidance diverges
in the timing and implications of the low-level disturbance and
resulting MCS. One of two scenarios is possible as the MCS moves
through the CWA: 1. the widespread cloud cover and robust cold pool
reduce any chance for further thunderstorm development, or 2. the
MCS produces a lingering boundary that will be the focus of
thunderstorm development later in the day. At this point, it is
still too early to diagnose which of these scenarios and their
mesoscale features will occur.
At the same time, the surface front from Wednesday will move
northward back into the region as a warm front along persistent
southerly surface flow Thursday morning. To the south of the front,
warm, moist, unstable air will create a favorable environment for
isentropic lift to generate showers and thunderstorms. Operational
and SREF guidance indicates 1500-2000 J/kg of mean SBCAPE and 30-40
kts of 0-6 km shear will be available during the afternoon.
Thunderstorm development and growth is most favorable across
central, east-central, and southeast Missouri where the highest
instability will occur. While an isentropically lifted thunderstorm
could grow upscale to become strong to severe, if the MCS produces a
boundary across our CWA the warm front could interact with the it to
effectively force deep thunderstorm development. Thunderstorms
that develop could become strong to severe, capable of producing
damaging winds and a few tornadoes. Lapse rates around 6 C/km will
limit any hail threat with thunderstorms that develop. By
Thursday evening instability will diminish as will severe
thunderstorm chances.
Showers and thunderstorms will linger across the area into the
evening Thursday and through the day Friday as a cold front is
pulled through the region by the mid-level trough. A surface high
will move into the region in the wake of this system, keeping the
Memorial Day weekend largely dry. Northwesterly winds and CAA will
pull temperatures down from their previous toasty values. High
temperatures on Friday will be chilly in comparison, peaking in
the low 60s across northeast Missouri and west-central Illinois to
low 70s across southeast Missouri. Temperatures will rebound
slightly over the weekend under mostly sunny skies with highs
still below normal in the upper 60s to mid 70s.
Beyond the weekend the WPC Cluster Analysis indicates that rain will
once again return to the region, though there is some uncertainty in
timing and location of features. Most of my attention has been paid
to the short term and Thursday system, and I have largely let the
National Blend of Models populate the extended period.
MRM
&&
.AVIATION... (For the 00z TAFs through 00z Wednesday Evening)
Issued at 639 PM CDT Tue May 25 2021
VFR flight conditions with light rain is expected to prevail
across much of the area this evening. There may be an embedded
heavy rain shower or thunderstorm that could cause the visibility
to briefly drop to IFR, but these look to be few and far
between. The majority of model guidance shows ceilings dropping to
low MVFR with a few spots of IFR after 06Z across most of the area
as low level moisture pools ahead of a weak cold front. These low
ceilings will persist for most of Wednesday morning, lifting and
scattering after 16-17Z. Light west-southwest wind overnight will
briefly shift to the northwest and then to the north Wednesday
afternoon, but will likely turn back to the south by the end of
the period.
SPECIFICS FOR KSTL:
VFR conditions are expected to prevail at Lambert this evening,
with light rain showers moving in after 00Z. There`s a small
chance that a heavier shower or thunderstorm could produce rain
that is heavy enough to drop the visibility to MVFR or IFR this
evening, but the probability is so low that I did not mention it
in the TAF. Ceilings are expected to drop to MVFR late tonight
between 06-08Z, and stay down until between 16-18Z ahead of a weak
cold front. The front will briefly turn the wind around to the
northwest and then north as it passes, but wind should be back
around to the south by 00Z Thursday.
Carney
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
831 PM CDT Tue May 25 2021
.UPDATE...
Impressively rich moisture has made its way westward into the
central South Plains with WTM observations showing dewpoints in
the upper 60s and lower 70s as far west as the Littlefield and
Smyer WTM sites. Despite the moisture and very strong
instability, convection has failed to initiate on the retreating
dryline across the South Plains, likely due to weak capping and a
lack of upper support. On either side of the South Plains, deep
convection did erupt over the Texas Panhandle as well as in the
Permian Basin. The northern convection is now approaching Happy,
though it is struggling of late. The more southern activity has
made its way northeastward into the southern Rolling Plains. This
convection is much more robust, as it ingests high theta-e
supporting MLCAPEs around 4000 J/kg. Given the trends, we will
likely be dropping the Severe Thunderstorm Watch for a good chunk
of the CWA shortly, though not across the southeast zones (where
robust convection continues) and across the north, where storms
are still possible.
&&
.PREV DISCUSSION... /issued 651 PM CDT Tue May 25 2021/
AVIATION...
Biggest question mark is whether or not convection will affect
the terminals this evening. Thus far storms have failed to develop
along the dryline located just west of KLBB and KPVW, while storms
have formed further north, to the west of KAMA, and south of
Fluvanna. The ongoing storms will avoid the western terminals, but
explosive storm development could still occur over the next hour
or two in near proximity to KLBB and KPVW. Given this, we have
maintained VCTS at the beginning of the TAFs. KCDS will have a
chance of seeing storms in the area later this evening, around and
after 03Z, but confidence isn`t high enough for more than a VCTS
mention. Depending how things play out tonight, there will be a
window for MVFR to IFR cigs Wednesday morning. Have hinted at
this, but not included a broken deck explicitly. Another chance
for thunderstorms will exist late Wednesday afternoon into the
evening.
PREV DISCUSSION... /issued 405 PM CDT Tue May 25 2021/
SHORT TERM...
As of 2PM the predominant area of subsidence aloft was over the
Rolling Plains and moving east with the overnight MCS currently over
east Texas. The stratiform portion of the cumulus field is rapidly
eroding with a prominent outflow boundary stretching from Vigo Park
southeast into Matador to just north of Aspermont. Another outflow
boundary earlier this morning that extended from Muleshoe to
Silverton isn`t as clear on radar early this afternoon, but can
still be seen in the surface observations. Both of these boundaries
should be important through the remainder of the afternoon and
evening wrt to convective initiation and evolution. As the
dryline mixes east out of eastern New Mexico through the remainder
of the afternoon, it will first interact with a robust theta e
axis currently extending from Morton southeast to Lake Alan
Henry. The most robust initiation indicated in multiple runs of
the HRRR is expected along and just east of the dryline between
4pm-6pm just west of the I27 corridor. The earlier and more
westward that initiation occurs will decide the extent of
thunderstorm coverage on the Caprock and especially areas
surrounding Lubbock County, where there were pockets of 1-2 inches
of rainfall and localized flooding last night, especially around
Buffalo Springs Lake and east Lubbock.
Farther south along and southwest of the ThetaE axis, dewpoints are
in the mid to upper 60s with pockets of CAPE over 4000J/K
extending from the city of Lubbock down to Lake Alan Henry. With a
robust CU field in place, steep mid level lapse rates exceeding
8.5 C/km and favorable hodographs the farther southeast you go,
all severe hazards are possible where storms initiate and mature.
Eventually storms are expected to be multi-cellular but any
discrete initiation may be supercellular early in their life cycle
and capable of producing very large hail and tornadoes,
especially in the vicinity of the ThetaE axis, where as of 2pm the
Post mesonet station is 81/69 with a light southeast wind.
As convective mode eventually goes upscale later this evening,
another MCS is expected to develop over the southern Rolling Plains
into the I20 corridor by midnight. Strong wind gusts and large hail
will still be a threat as the convection pushes east-southeast out
of area by around midnight. We`ll see mild temperatures overnight
with plenty of moisture in place and more favorable upper level
dynamics for strong to severe thunderstorms again tomorrow
afternoon, initiating along the dryline in vicinity of the NM/TX
state line and moving northeast through the evening hours. Most of
the forecast area is highlighted in a `Slight Risk` by the SPC for
tomorrow, again with all severe hazards possible including tornadoes.
LONG TERM...
Active weather appears likely to stick around through the long term
period as the upper level pattern remains transient and amplified.
Early on Thursday, upper level flow will return to southwesterly as
an upper trough sweeps across the Desert Southwest. With difluence
aloft and an uptick in shear compared to past days, severe weather
appears plausible as the dryline sets up across the western and
central South Plains during the afternoon.
On Friday, flow overhead becomes more zonal as an upper trough
transits over Montana with another, deeper trough rotating through
the Great Lakes. As this occurs, a surface low moving east over the
Ohio Valley combined with the influence of a building ridge over the
Upper Midwest will send a weak backdoor front into our area from the
east on Friday. This setup bears watching, as the surface evolution
combined with ample instability and continued low level moisture
advection Friday may combine to produce a heavy rain and severe
weather threat heading into the holiday weekend.
Saturday, the upper level pattern looks to amplify yet again as
another 500 mb trough moves ashore over Southern California.
Guidance is in relatively good agreement that this trough will slow
its eastward progression over the weekend, with both the GFS and
ECMWF keeping the low lingering in the vicinity of the Four Corners
throughout the weekend. If this turns out to be correct,
southwesterly flow would be present aloft over our area for several
days. With a persistent surface ridge locked in place to our east,
southerly to southeasterly surface flow would continue to pump
moisture into the CWA, with PWATs perhaps near the the percentile
of climatological values. With the upper low lingering to our
west, a sloshing dryline scenario appears plausible this weekend,
leading to thunderstorm chances each afternoon and evening as the
dryline pushes east into the area. Certain specifics of the setup
remain uncertain, such as the magnitude of capping/inhibition and
the effects of overturning from prior convection. However,
instability and shear look to remain generally sufficient to
support severe weather each day. Next week, guidance begins to
differ on the evolution of the upper level pattern, however a
decent signal exists which points to the possibility of
southwesterly upper flow remaining in place, suggesting that
thunderstorm chances continue into the middle of next week.
In terms of practical weather, at this time it appears that this
weekend has the potential to be quite active, with thunderstorm
chances each day. While it is too early to nail down the precise
evolution of how any rain and storms evolve, it does appear that
severe weather, heavy rain, and localized flooding will make an
appearance at some point during the holiday weekend. Stay tuned as
the details evolve over the coming days. /DWK
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
23/30
Area Forecast Discussion
National Weather Service Midland/Odessa TX
141 PM CDT Tue May 25 2021
.DISCUSSION...
Veered, albeit weak, 7h winds suggest the dryline will evetually
move to near a Lamesa to Odessa to near Alpine line with a mstr
rich and unstable condition e of the dryline with ML CAPEs
2500-3000 J/KG. Storm initiation has occurred in far e Jeff Davis
Co and n Brewster, very close to HRRR forecast. These storms are
forecast to move e and increase across Pecos Co where severe
storms could develop between 20Z-21Z. Surface dewpoints are high
at Sheffield early this afternoon 68. Between 00Z-03Z/Wed a second
area of storms may develop across the cntrl and ern PB. Deep
layer shear in general is 20-25kts, but instability is likely to
make up for it and severe storms will certainly be possible. Wed
7h winds back to the s and dryline will remain much farther w
where some of the hottest surface temps will be, mid to upper 90s
SE NM- Upper Trans Pecos-wrn PB. A few strong storms will develop
in those areas, but coverage will be limited with SB CINH stronger
farther e. Deep layer shear will increase to 30-35kts on Thu as
sw flow at 7h signals dryline will mix/move farther e. SB
instability axis is likely to be focused along a narrow corridor
from near Lamesa- Midland/Odessa-Crane- Bakersfield. Sustained
se-s low-level flow will increase convergence along dryline.
Initial development is certainly possible, if not favored, along
and just n of a dryline bulge between Penwell and Saragosa. Using
30 degrees right of 7h wind for storm motion would bring
strong/severe storms into the Midland/Odessa area early evening.
However, storms could be strong right mover (following mstr axis)
bringing higher end severe threat into srn PB and e Pecos Co..
Still coverage is minimized, however potential intensity of storms
could make up for it? Another interesting day Fri with
outflow/cold front e-w along I-20, dryline extending s from cntrl
PB with model indications of a thermal low or mesolow across wrn
PB. Boundaries will be good focus for tstm development, but where
the boundaries will actually be is difficult to say, so for now
suffice it to say slight chance to chance storms possible Fri
afternoon-evening. There may be a few storms Sat, but the better
potential will start Sun across the wrn areas and then expand e
Mon ownward as a slow moving mid-level trof moves into the Desert
SW. Sunday through mid week or so could be an active period with
all severe wx threats possible, including flooding. Over the next
few days temps will remain above normal by a few degrees, but by
next week with mid- level trof to w and increased rain high temps
are likely to cool back closer to normal or below.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 68 91 70 92 / 20 10 10 10
Carlsbad 63 96 65 97 / 0 10 20 10
Dryden 71 94 71 96 / 30 0 10 20
Fort Stockton 69 96 70 98 / 20 20 10 20
Guadalupe Pass 66 90 65 91 / 0 10 10 10
Hobbs 64 93 66 94 / 0 20 20 10
Marfa 57 92 58 95 / 10 20 10 10
Midland Intl Airport 68 93 70 94 / 20 10 10 20
Odessa 69 93 70 94 / 20 10 20 20
Wink 68 98 70 99 / 10 20 20 20
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
940 PM EDT Tue May 25 2021
.SYNOPSIS...
Offshore high pressure will extend over the area through
late week as a weak trough of low pressure lingers inland.
A more active weather pattern expected by the weekend as a
cold front pushes through the area Saturday with waves of
low pressure developing along it. High pressure will build
over the area Monday and Tuesday. A fairly uniform and quite
warm night upcoming with lows upper 60s well inland and low/mid
70s near the coast.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 940 PM Tue...Shower activity over Duplin county has
dissipated with all areas across eastern NC now dry. Stubborn
mid-level cloud deck lingers along the US 70 corridor and may
complicate overnight fog potential in recently saturated
locales. For now will leave patchy fog mention in the forecast.
Prev disc...Radar and satellite imagery showing thunderstorms
along the sea breeze inland at mid-afternoon mainly west of
Highway 17 in the Coastal Plains counties. Craven County, in
particular, has had fairly widespread rain coverage this
afternoon. Light mid- level flow has led to little movement of
the precipitation, so a few areas getting beneficial rain this
afternoon. Cirrus shield from the convection has spread back
toward the coast as well. The precipitation should end with loss
of heating at or before dark.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
As of 330 PM Tuesday...Despite some lowering in the mid-level
height field on Wednesday, high-resolution models show minimal
precipitation in our area as low-level flow becomes more SW/WSW.
Surface forcing looks weak and will keep the forecast dry on
Wednesday with model guidance support very warm high
temperatures in the mid to upper 90s along and west of the
Highway 17 corridor, upper 80s southern coast and mid 80s Outer
Banks.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
As of 310 AM Tuesday...A hot and dry pattern will persist
into late week with temps staying above climo for late May.
Dominant ridge begins to break down by the weekend as a more
active weather pattern emerges.
Wednesday Night and Thursday...Winds shift more westerly
Thursday, allowing for better downslope flow to keep temps
inland around the mid 90s. Some guidance suggest a weak
shortwave trough aloft will move through ENC Thursday afternoon,
coincident with peak heating, which warrants an increase in
PoPs to 20-25% most areas. Decent instability but weak shear and
lack of moisture will result in isolated showers and
thunderstorms with this weak feature aloft.
Friday through Saturday...Upper level ridging pattern shifts
south Fri in response to a trough aloft moving into the Ohio
River Valley and into the Mid-Atlantic region by Saturday. The
surface ridge shifts offshore Fri, followed by a modest cold
front moving south-southeast into the region during the day on
Saturday, presenting the next best chance for measurable
precipitation through the long term forecast period. Afternoon
highs drop into the low 90s Fri and low-mid 80s Sat.
Sunday into Monday...the upper trough will slowly shift into New
England Sunday into Monday, dragging the cold front offshore and
well off the coast by late Mon. High temps will fall into the
70s Sun, then into the low 80s on Mon.
&&
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
SHORT TERM /through 00Z Thursday/...
As of 730 PM Tue...VFR conditions prevail across the TAF sites
this evening with SSE flow at 5-10 kt. Main sticking point in
forecast tonight will be the potential for patchy fog at
terminals that saw appreciable rainfall, mainly EWN and ISO.
HRRR soundings show slightly more favorable low-level moisture
profiles for at least some patchy instances relative to PGV/OAJ,
and introduced vis restrictions to TAFs. Otherwise VFR
overnight with only a few high clouds.
VFR tomorrow with winds veering SW and increasing to 5-10 kt
with gusts to 15 kt or so during the afternoon. Rain chances at
the terminals are minimal.
LONG TERM /Wednesday Night through Sunday/...
As of 320 AM Tuesday...VFR conditions will prevail through the
long term but cannot rule out patchy light fog during the late
night/early morning hours. A cold front will move through
Eastern NC on Saturday, producing showers and thunderstorms
which will have the potential to reduce aviation conditions.
&&
.MARINE...
SHORT TERM /through tonight/...
As of 345 PM Tuesday...Winds have largely veer to E/SE at late
afternoon at 5-15 knots with seas 3-5 feet. All Small Craft
Advisories have expired on area waters. High pressure will
continue to build in from the NE tonight. Winds becoming S later
tonight and SW 10-15 knots with 15-20 knots in the afternoon and
a few occasional gusts to 25 knots are possible Wednesday
afternoon. Seas will hover in the 3-5 foot range for most waters
tonight and Wednesday.
LONG TERM /Wednesday Night through Sunday/...
As of 330 AM Tuesday...Winds shift more SW Wed night through
Friday as an offshore high strengthens, with winds relaxing to
10-15 kts Thu and Fri. Seas drop to 2-4 ft Thu and Fri.
Conditions deteriorate Saturday as a cold front moves from north
to south through the ENC waters. Winds shift N/NE by Sat
afternoon with seas beginning to build from north to south by
Sat evening. Next round of SCAs expected by Saturday Night and
could last into Memorial Day.
&&
.CLIMATE...
Record High temps for 5/26 (Wednesday)
LOCATION TEMP/YEAR
New Bern 100/1953 (KEWN ASOS)
Cape Hatteras 88/1962 (KHSE ASOS)
Greenville 99/1927 (COOP - Not KPGV AWOS)
Morehead City 96/1953 (COOP - Not KMRH ASOS)
Kinston 96/2011 (COOP - Not KISO AWOS)
Jacksonville 96/2019 (KNCA ASOS)
Record High temps for 5/27 (Thursday)
LOCATION TEMP/YEAR
New Bern 96/1989 (KEWN ASOS)
Cape Hatteras 89/2019 (KHSE ASOS)
Greenville 96/1972 (COOP - Not KPGV AWOS)
Morehead City 88/2006 (COOP - Not KMRH ASOS)
Kinston 98/2019 (COOP - Not KISO AWOS)
Jacksonville 97/1989 (KNCA ASOS)
Record High temps for 5/28 (Friday)
LOCATION TEMP/YEAR
New Bern 95/1941 (KEWN ASOS)
Cape Hatteras 88/2019 (KHSE ASOS)
Greenville 98/2019 (COOP - Not KPGV AWOS)
Morehead City 94/2019 (COOP - Not KMRH ASOS)
Kinston 93/2019 (COOP - Not KISO AWOS)
Jacksonville 95/1967 (KNCA ASOS)
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement from 8 AM EDT Wednesday through
Wednesday evening for NCZ196-203>205.
MARINE...None.
&&
$$
SYNOPSIS...MHX
NEAR TERM...CTC/MS
SHORT TERM...CTC
LONG TERM...DAG
AVIATION...DAG/MS
MARINE...DAG/CTC/CQD
CLIMATE...MHX
AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
830 PM EDT Tue May 25 2021
.SYNOPSIS...
A warm front will lift back northeast through central NC
Wednesday morning. The hot air mass to the south will return to
NC on Wednesday. A strong cold front will approach from the
northwest late Friday.
&&
.NEAR TERM /TONIGHT/...
A main outflow boundary had curled to the ESE into far NW Forsyth
County as of 830 PM. The northern portion of the outflow had surged
NE into Stokes/Patrick VA. There is still an opportunity for
scattered showers and isolated thunderstorms in the Triad,
especially the Winston-Salem area into late evening.
Another outflow boundary had entered the SW Piedmont from Charlotte
to Wadesboro. It appears the best instability is located to the
west, or near the old boundary. Therefore, only an isolated chance
of a shower in the SW Piedmont for the next hour or so.
It is becoming more stable in the east with loss of heating. The sea
breeze had pushed to near Raleigh and Fayetteville with only a
subtle wind shift noted.
Previous discussion as of 604 PM this evening...
A chance of a shower or storm in the far NW and the far SE through
1000 PM. Dry and pleasant elsewhere.
The latest data analysis indicated mixed layer CAPES on the order of
1000 j/kg in the far NW Piedmont, with more stable conditions to the
east out over the Piedmont. The low level boundary had "backdoored"
westward into the eastern slopes of the Blue Ridge. Scattered slow
moving thunderstorms have developed over the higher terrain around
Boone, West Jefferson, and Glade Valley. Some of the storm have
extended out over the Foothills nearing Wilkesboro and Mount Airy.
The latest RAP indicated that the showers/storms should continue
going for the next couple of hours before nightfall convective
inhibition takes over. We will eliminate chances in the Winston-Salem
and Greensboro areas through 700 PM, then carry a chance of showers
and isolated storms between 700 and 1000 PM in that region (NW part
of the Triad) before the convection dies off late evening.
Elsewhere, the sea breeze has moved into the Coastal Plain. However,
convergence and instability are on the wane there. There is still a
a chance of a quick shower or storm in Sampson/Wayne/SE Johnston
through mid-evening.
Otherwise, partly cloudy skies are expected tonight with lows in the
63-68 range.
Previous discussion issued as of 156 PM Tuesday...
Latest analysis shows yesterday`s backdoor front has pushed well to
our south and is currently stationary across central SC and extends
across upstate SC then northward along the NC foothills. The airmass
north of this boundary and over us remains moist and stable per
latest mesoanalysis. This morning`s stratus is breaking up, so
we`re finally seeing sfc temp readings beginning to climb into the
low 80s. Farther east, the clouds broke up much earlier, and thus
with better instability when coupled with the sea breeze, we`re
seeing some showers near the coast. These showers may move wwd and
eventually approach our ern-most zones; but farther west across our
Piedmont zones, most of the recent CAMs suggest showers will have a
difficult time developing given the aforementioned stability. Should
any showers develop in our CWA, the would likely be near the edges
of the earlier stratus shield, namely across our southern and
western zones. Thus will carry slt chance PoPs this evening for
those zones, but otherwise most of central NC should remain dry.
Finally, should any cells develop, with PWAT around 1.5-1.8 inches
and given weak deep layer flow, the isold spots that see such
showers could see very localized heavy downpours. The risk for
showers will quickly diminish after sunset, with partly to mostly
cloudy skies lingering overnight. Lows in the 60s.
&&
.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
As of 156 PM Tuesday...
Look for fair and hot weather during the daytime hours Wednesday
with highs temps climbing to the low to mid 90s (highest south). But
during the evening and Wednesday night, a short wave trough will
cross the Ohio Valley and eventually the Mid Atlantic region later
at night, with a band of showers and tstms along and ahead of this
feature. While guidance suggests most of this activity will remain
to our north across VA, we can`t rule out the southern tail end of
these showers to move across our zones north of Hwy 64 late
Wednesday and Wednesday night. Will include a slight chance PoP
across our northern zones during that time. Lows Wednesday night
in the upper 60s to around 70.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 156 PM Tuesday...
Not much change in the guidance with respect to Thursday, as a weak
shortwave trough will move through the area during the early part of
the day. Ridging behind the trough to the west and the development
of a weak coastal front to the east should allow for the development
of isolated showers and thunderstorms east of I-95 during the
afternoon. Given weak forcing and meager shear/instability, I`m not
anticipating much in the way of a severe threat. Thursday will be
another warm day with highs in the low to mid 90s. Lows bottoming
out in the mid/upper 60s.
Larger scale forcing for ascent will move in from the west during
the afternoon on Friday with a a surface low forecast to move
through Delmarva early Saturday morning. The associated surface cold
front is expected to cross the mountains during the afternoon/early
evening hours and most of the available deterministic guidance, as
well as the majority of ensemble members, suggest measurable precip
across a good portion of the area Friday evening. That being said,
amounts don`t look terribly impressive (despite nearly 2" PW`s) and
not nearly enough to eradicate the drought, but it`s rain
nonetheless. Thermodynamic parameters appear to be supportive of a
mention of thunder with at least a few hundred J/KG of MLCAPE to
work with coincident with the frontal passage along with 30kts of
deep layer shear. 00Z deterministic ECMWF is a big slower with FROPA
and keeps things drier, but ECENS appears to be a bit on the wetter
side and more in line with other solutions. Regardless, temps will
warm into the low/mid 90s ahead of the front, dropping into the low
to mid 60`s behind it.
The upper air pattern on Saturday morning will feature a
southwesterly flow across the Carolinas with a southeastward
advancing shear axis moving across central and eastern NC during the
morning and afternoon. A more prominent upper trough with a closed
low across the southern Great Lakes on Saturday morning will drop
southeast into the central Appalachians by Sunday morning. At the
surface, a trough enhanced by convection on Friday/Friday night will
be located across the eastern Carolinas with a much stronger but
slow moving front crossing the mountains on Saturday morning and
pushing south and east across the Carolinas through Saturday night.
Guidance is suggesting that a weak surface wave may develop across
the southern Carolinas slowing the southward progression of the
front. Scattered showers and thunderstorms are expected on Saturday
and Saturday night with the greatest coverage across the east and
northeast in a region of deeper moisture and ahead of the initial
shear axis. Highs on Saturday will be variable with the front moving
across the area. Highs will only reach the lower 70s near the VA
border but will reach the lower to possibly mid 80s near the SC
border. Lows on Saturday night will range in the 50s.
There remains some model uncertainty in the progression of the
strong upper trough across the mid Atlantic with the operational EC
moving the trough off the coast by midday Sunday with more recent
GFS slower and moving the trough off the coast on Monday morning.
May need to hold onto some low chance PoPs across the east into
early Sunday. With morning low level thickness values in the 1340s
and 1350s, it will be a cool day on Sunday with highs only in the
lower 70s north to the upper 70s south.
The upper trough should move offshore by Monday with a northwest to
westerly flow aloft developing across the Carolinas into Tuesday as
upper level ridging begins to develop across the Deep South for
early next week. This should result in a period of generally fair
and dry weather. Highs in the upper 70s to around 80 on Monday will
moderate into the lower to mid 80s on Tuesday. -Blaes &&
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 750 PM Tuesday...
Through 00Z Thursday: Generally VFR conditions to continue across
central NC through the period. Isolated MVFR conditions with showers
are possible near KINT through 03z/tonight.
After 00Z Thursday: VFR conditions are expected late Wednesday and
Thursday as any shower or storm chances will be minimal. Higher
chances of showers are expected Friday PM and continue into the
weekend.
&&
.CLIMATE...
High temperatures that could be broken this week:
Raleigh: Wednesday, May 26: 94 set in 2019
Thursday, May 27: 96 set in 1916
Greensboro: Wednesday, May 26: 95 set in 1926
Fayetteville: Wednesday, May 26: 100 set in 1953
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...np
NEAR TERM...Badgett/np
SHORT TERM...np
LONG TERM...DL/NL/BLAES
AVIATION...Badgett/np