Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/28/21
AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
1054 PM CDT Thu May 27 2021
.SHORT TERM...(This Evening through Friday)
Issued at 250 PM CDT Thu May 27 2021
27.1930Z regional radars show the last of the more moderate
rainfall lifting north and east of the forecast area. That said,
expect additional light shower development over the next few hours
moving from northwest to southeast as the primary vort lobe aloft
moves across the region. Latest HRRR suggests these showers may
drop as far south as the I-90 corridor before moving out
overnight. As a result, expect cloudy/cool/wet conditions to
continue through this evening for most areas.
Attention then turns to frost potential overnight. With daytime
highs today only in the upper 40s to mid 50s, it`s not going to
take much for overnight lows to flirt with the mid 30s. This is
most likely along and north of the Highway 14 corridor from Huron
to Brookings to Marshall, but is highly dependent on cloud cover.
Right now, it appears that low stratus will hang tough in these
areas until around 12Z tomorrow morning. This, combined with a
light northeast wind should preclude most areas from seeing
widespread frost. Will re-evaluate this evening to see if an
advisory is necessary, but will hold off for now. Nevertheless, it
will be a cold night for late May standards with lows a solid
10-15 degrees below normal.
Friday will be dry with increasing sunshine as 500 hPa short-wave
ridging moves across the region. Still cool in the wake of
tonight`s wave, but highs should climb into the upper 50s to lower
60s. Winds will be light from the east-northeast.
.LONG TERM...(Friday Night through Thursday)
Issued at 250 PM CDT Thu May 27 2021
For Memorial Day Weekend, a broad long-wave trough will slowly
wander across central Canada, allowing multiple short-waves to zip
across the Northern Plains in west-northwest flow aloft. For any
particular location, it won`t be a wash out, but do expect
periodic showers and isolated thunderstorms through Memorial Day.
Best chances right now look to be west of I-29 on Saturday and
across portions of southeast SD into northwest IA on Sunday.
Memorial Day stands the best chance to be relatively dry with
highs climbing into the lower to mid 70s. The good news is with
relatively little (if any) instability, severe weather is not
expected at this time.
The wave-train continues into the middle of next week, although
the synoptic flow becomes much more amplified with a building
ridge across the western CONUS. This will help lift temperatures
to more normal early June values with highs back into the lower to
mid 70s. Medium range model differences preclude anything more
than a 20-30 POP, but there remain additional shower and
thunderstorm chances through much of next week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1051 PM CDT Thu May 27 2021
Latest satellite imagery continues to show stratus deck gradually
sinking south across the Northern Great Plains, causing IFR to
MVFR cigs to prevail across much of our area. Unfortunately, will
not see much improvement to cigs overnight, as cloud cover and
isolated light showers linger through early Friday morning. Should
start to see stratus gradually lift after daybreak though,
allowing VFR levels to return to all TAF sites by Friday
afternoon. Otherwise, look for northeasterly winds to prevail
overnight before turning more easterly/southeasterly throughout
the day Friday.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&
$$
SHORT TERM...Rogers
LONG TERM...Rogers
AVIATION...SSC
Area Forecast Discussion
National Weather Service Grand Rapids MI
1102 PM EDT Thu May 27 2021
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 325 PM EDT Thu May 27 2021
- Rainy breezy and chilly into Friday afternoon
- Cool but dry through Monday
- Slow warming and turning wet mid to late next week
&&
.UPDATE...
Issued at 1102 PM EDT Thu May 27 2021
Forecast is on track with all areas set to see rain tonight. Main
driver of precipitation tonight is strong isentropic lift best
seen on the 300K surface. Strong 35-40 knots of flow is moving
directly up the surface producing the rain. Most concentrated rain
is occurring across Central Lower Michigan at this time, but it
should fill in across the south as well tonight.
&&
.DISCUSSION...(This evening through next Thursday)
Issued at 325 PM EDT Thu May 27 2021
- Rainy breezy and chilly into Friday afternoon
Rain will slowly overspread the area from northwest to southeast
into this evening. Most of the forecast area may not see much
rain until after 9 pm tonight. Most of the rain will occur
between 9 pm tonight and 10 am tomorrow. It will get rather
breezy too, winds of 15 to 25 mph with gusts over 30 mph are more
expect over most of our area too tonight into Friday during the
day. Temperatures will mostly be in the 40s tonight and during
the day tomorrow.
There continues to be a small threat of wet snow mixing in with
the snow near Route 10, east of US-131 during the early to mid
morning hours of Friday. Several of our model sounding from the
00z, 06z and 12z runs suggest a deep layer of near or just below
freezing temperatures there with a freezing height in the area of
1500 ft. So, while not strictly in the forecast, it is possible
northern parts of our forecast area may see some wet snow.
What is causing the rain? There is Pacific Ocean origin storm
system that is currently tracking east across the CONUS and it
has brought some precipitation near the Canadian board to the Gulf
Coast. It also caused a significant severe weather outbreak over
the western plains with a several tornadoes. As this system
continues to track eastward, it will continue to have good Gulf
inflow with it. It has a closed upper low (typically facilitates
for more impactful storm system) with, that this morning was over
the Dakotas. The upper low is expected to track east southeast
over Chicago Friday night and into Ohio on Saturday. This caused
an area of strong mid-level frontogenesis (FGEN) that tracks over
our forecast area Friday (centered near I-96). There is also
decent Q-vector convergence at mid levels that tracks across our
CWA Friday. In front of the system we have strong warm advection
resulting in 40 knots of isentropic lift which saturates the air
being lifted so CPD fall to near 0 mb from near 925 mb to over 500
mb later today into midday Friday. This results in two
precipitation events. The warm advection wing of the system
(tonight) then the deformation part of the system Friday during
the day.
The FGEN aspect of this event means there will be a narrow band
of heavier precipitation crossing our CWA with this event. All of
our convection allowing models are showing a narrow band of
around 1.5 inches of rain from this event. However different
models have that band in different areas. The 12z HREF has the
heaviest precipitation amounts north of Route 20 and south of
I-94. The ARW,NSSL, NAM 3 KM, HRRR, and GFS all have that northern
area of heavy rain. However the southern area of heaver rain in
the models are all over the place. Some have it south of
Michigan, some well south of Michigan others as far north as I-94.
The GFS has 3 bands of heavy rain, it has the northern and
southern one but also a band near I-96.
There is a thunderstorm threat, mostly over our southwest CWA
during the early to mid morning hours while that area is in the
warm advection part of the system.
Tonight we will have the warm advection showers (isolated
thunderstorms southwest quarter of our CWA). Most of our area
will see this late this evening into mid morning. Then we will
have the deformation precipitation from mid morning to early
evening on Friday. Where this sets up is the questionable part of
this event. The channel of mid level air that is the deformation
zone will be shifting slowly southward Friday as the upper low
rotates southeast into Ohio. This favors area south of I-96 seeing
most of the rainfall Friday during the day. Whatever area gets
this will see rain most of the day tomorrow.
The dry air moving in from the north, behind the storm will bring
clearing from north to south during the evening hours. Some patchy
frost is possible over northern sections toward sunrise Saturday.
Winds will remain breezy into Saturday evening so that will
diminish the risk of frost Saturday morning, still some protected
area may see frost.
- Cool but dry through Monday-
Over the weekend (Memorial Day weekend) the next Pacific system
comes across Canada and builds a ridge in front of it. This helps
push tonights system off shore. The result of all of this is
mostly clear skies and pleasantly cool temperatures. There is a
threat of frost Saturday morning but more likely Sunday morning
since winds will be much lighter Sunday morning.
On Monday the trailing part of the upper level system crossing
Canada will have a shortwave tracking just north of Michigan. That
may cause a few showers later Monday into Monday night but it is
a low chance sort of thing.
- Slow warming and turning wet mid to late next week-
The next upstream Pacific system digs a trough over the northern
and western plains by mid week. This result in frontal boundary
stalled south of Michigan. Since the primary polar jet will be
south of Michigan most of the week, the really summer like weather
sill stay south of here. Still there is a front and any wave on
that front could bring showers into the area as early as
Wednesday. However, the greater threat for showers and storms
would be the fist weekend in June. At that time the developing
western plains system will be tracking toward the Great Lakes,
bringing us our next significant precipitation event.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 826 PM EDT Thu May 27 2021
Low pressure will swing through the Southern Great Lakes region,
moving from Illinois to Ohio the next 24 hours. Stronger northeast
winds will prevail the next 24 hours as well, sustained between
10-20 knots with gusts in the 20-30 knot range. Ceilings will
lower tonight to IFR towards daybreak and remain low/IFR through
much of Friday. Rain will spread across the TAF sites as well
tonight and Friday morning. Visibilities should stay MVFR for the
most part late tonight and Friday morning in the rain. Conditions
will improve Friday evening and Friday night.
&&
.MARINE...
Issued at 325 PM EDT Thu May 27 2021
We upgraded our gale watch to a gale warning from around Pentwater
south. This was based on both the ECMWF ensemble wind gust
forecast, looking also at the HRRR and HREF wind forecasts. These
all suggested the stronger winds will be off shore, mostly south
of Grand Haven.
We may need some sort of beach hazard statement for Saturday as
the wind starts to become more northerly and than in the
afternoon starts to turn on shore. This would likely cause
significant hazards to any swimmer in Lake Michigan.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory until 8 PM EDT Friday for LMZ849.
Gale Warning until 8 PM EDT Friday for LMZ844>848.
&&
$$
UPDATE...Duke
SYNOPSIS...WDM
DISCUSSION...WDM
AVIATION...Duke
MARINE...WDM
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
956 PM EDT Thu May 27 2021
.SYNOPSIS...
A low pressure system will approach tonight and move through on
Friday. An upper level disturbance will linger precipitation
into Saturday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
At 02z, radar currently shows a few weak cells tracking NE through
the northern Miami Valley. As these cells begin to push out of
the fa, the main band of showers that will impact our CWA are
currently tracking through western Indiana. CAMs seem to
disagree on the timing, structure and overall strength of the
MCS moving into the Ohio Valley tonight. While the NAM3K shows a
fairly robust linear structure in this system moving into our
western counties just after 06z, the RAP and HRRR are slower by
a couple of hours and resolve a much more broken structure that
leaves these showers being more scattered (and weaker) in
nature. Based on current radar trends, thinking that the HRRR
and RAP will end up resolving a bit better. The MCS has lost of
lot of its convective elements north of the Indiana border, and
it only looks like our far southern counties /mainly along and
south of the OH river/ have a chance of hearing some thunder
tonight with these showers. With very weak instability, the
severe potential for any storms tracking through our CWA tonight
will be very low. Nonetheless, episodic rain showers are
expected everywhere, so kept Categorical PoPs in all of our
counties.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
During the day on Friday a cold front will work through the
region. There will be the potential for some isolated strong to
severe storms during the afternoon and into the early evening
hours, primarily southeast of Interstate 71. Kept severe mention
in the HWO. Temperatures will be cooler on Friday across
northwestern portions of the forecast area with the position of
the low and with the cooler air moving in sooner in this area.
Have high temperatures ranging from the lower 60s across far
northwestern portions of the region to the middle 70s across the
south and southeast. Isolated wind gusts will be possible in
advance of the frontal boundary, however expect additional gusts
after the passage of the frontal boundary.
Working into Friday night expect additional shower activity and
wind gusts as an upper level disturbance moves through. With the
cooler air moving into the region have low temperatures dropping
down into the 40s across most areas.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Mid level low to migrate slowly east through Ohio Saturday and then
through the Eastern Great Lakes Sunday. This low will offer very
cool temperatures and a chance of showers Saturday. Expect highs
Saturday to run in the upper 50s to lower 60s or 15 to 20 degrees
below normal.
As the low translates east any small chance for a shower in the east
on Sunday will end early. Temperatures will begin to moderate, but
continue below normal with highs in the upper 60s to lower 70s.
Zonal flow early next week with surface high pressure over the area.
This will lead to dry weather conditions and a warming trend.
Temperatures on Monday will be closer to normal with highs in the
mid and upper 70s.
A progressive and weak northern stream short wave to track through
the Great Lakes Tuesday. Model solution spread exists regarding the
amplification of this system. Confidence is not high and therefore
will limit any mention of precipitation on Tuesday to only a slight
chance. Expect continued near normal temperatures with highs of 75
to 80.
Energy digs south with mid level low developing over the
Central/Southern Plains late in the week. Mid level flow over the
Ohio Valley ahead of this system backs southwesterly on Wednesday --
which leads to an increase in moisture. Have chance pops for showers
and thunderstorms Wednesday. Chances for showers and thunderstorms
increase on Thursday as better instability looks to develop.
Temperatures continue to slowly increase with highs Wed/Thu ranging
from the upper 70s to lower 80s.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Rain showers move in tonight ahead of another cold front. Episodic
rain showers are forecast through the majority of the taf
period, but only a slight chance of thunder exists.
Initial line of showers make their way into far western taf
sites near 06z tonight. Limited VCTS mention to just KCVG/KLUK
as instability weakens further north. Current trends show weaker
convective activity and thus lower probabilities for thunder
tonight. MVFR CIGs and vsbys are forecast shortly after the
onset of rain, followed by IFR CIG reductions closer to 12z
Friday morning. A prolonged period of IFR CIGs are forecast through
Friday, while only intermittent periods of IFR vsbys are
expected with any heavy downpours.
More breaks in the rain showers possible during the mid to late
morning hours on Friday before another line of showers moves
through Friday afternoon along the front - again likely seeing
limited thunder chances. A few isolated wind gusts of 20-30 kts
are possible, so included higher gusts in the tafs for Friday
afternoon.
IFR CIGs look to persist through the extended KCVG taf period
for now based on guidance. However, the bulk of rain showers
will have ended by 00z Saturday.
.OUTLOOK...MVFR to IFR conditions are possible through Saturday
morning.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Novak
NEAR TERM...Clark
SHORT TERM...Novak
LONG TERM...AR
AVIATION...Clark
Area Forecast Discussion
National Weather Service Indianapolis IN
1122 PM EDT Thu May 27 2021
...Updated Aviation Discussion...
.Forecast Update...
Issued at 946 PM EDT Thu May 27 2021
Surface analysis this evening shows low pressure in place over
Missouri...along with a warm front extending northeast to northern
Indiana and a cold front extendeding sw to OK and TX. GOES16 showed
strong convection in place ahead of the cold front over SW
MO...while much warmer tops were found across Indiana as showers
were waning. A warm amd moist atmosphere was in place across Indiana
with dew points in the 60s. Water Vapor imagery shows a deep upper
low in place over the Dakotas...nudging a broad trough east toward
the Ohio Valley.
Radar trends showa waning shower complex over southwest
Indiana...and the next set of echo was found ocver western Illinois.
Thus with the unfavorable environment for strengthening convection
across Indiana with CIN in place along with low CAPE...have reduced
pops for the next few hours across the northern parts of the
forecast area...but kept pops in place across the south for the
waning system. Will expect a few hours of dry weather before
06Z...with the echos over IL and development ahead of the broader
trough expected to push across Indiana late overnight. Thus have
rammped up temps then. Given the clouds and rain...trended overnight
lows warmer than the previous forecast.
&&
.Short Term...(This evening through Friday night)
Issued at 312 PM EDT Thu May 27 2021
A quasistationary front turned warm front is currently over northern
portions of central Indiana this afternoon. Over central Illinois
and approaching from the west is the eastern extent of a broad zone
of convective activity south of a baroclinic zone that includes the
actual boundary and multiple effective outflow boundaries that
stretches back into the central Plains. Thanks to weaker instability
and effective shear with eastern extent, expect the northern portion
of this zone to weaken as it moves into the area, although it will
still be capable of heavy downpours and a few strong gusts. The
overall line has been filling in to the southwest and connecting to
other more substantial severe storm activity over Missouri and back
into Oklahoma. Suspect that the more robust instability to our
southwest will drive the majority of severe activity this afternoon
and evening into the lower Ohio Valley and mid-lower Mississippi
Valley, with only a few isolated strong storms possible over the
area this evening.
Overnight, expect showers and scattered embedded thunderstorms
across much of the area as the surface low approaches the area,
albeit with more of a marginal hydro threat than anything as
instability wanes diurnally but profile becomes deeply saturated and
pseudotropical in nature. The more substantial activity to our south
and west may sap some moisture and limit the hydro threat even
further.
A dreary and damp day can be expected Friday with showers and
perhaps a few isolated and elevated thunderstorms associated with
the trailing upper low as it passes through the area. Some marginal
elevated instability is present and justifies an isolated thunder
mention during the daytime hours. Later into the afternoon and
overnight Friday night, showers may linger, or more likely drizzle,
as the profile begins to quickly dry out aloft but low level
moisture remains below a midlevel inversion.
Blend temperatures required only minor tweaks through the short
term. Expect a fairly substantially non-diurnal temperature
progression late tonight into Friday, with highs likely to be
reached early in the day before falling in the afternoon in the wake
of the surface low.
&&
.Long Term...(Saturday through Thursday)
Issued at 312 PM EDT Thu May 27 2021
As the long term begins, an upper low is moving slowly through the
Great Lakes and slides to Ohio Saturday morning, with an upper
trough trailing behind it to the southwest that moves through during
the day on Saturday, and this could keep some clouds around and
perhaps even some light showers/drizzle in the eastern counties into
the day on Saturday. Cold advection will also be in place. Cool
surface high pressure will build in from the northwest by Saturday
night, and this should bring an end to any precipitation chances by
Saturday evening. Saturday night should see clearing skies under the
influence of high pressure, and much cooler than normal temperatures
for this time of year for lows (low to middle 40s). Upper ridging
and surface high pressure on Sunday should make for a mostly sunny
and dry day, and with the cooler air mass in place highs should be
in the upper 60s to lower 70s. The pleasant conditions will continue
through the rest of the holiday weekend under the influence of an
upper ridge. By Monday night, though, the upper ridge gets somewhat
suppressed by a shortwave, and chances for showers and a few
thunderstorms will arrive as a frontal system approaches and a front
stalls somewhere in the vicinity of central Indiana, necessitating
the inclusion of PoPs through the rest of the forecast period from
Tuesday onward. Temperatures start to slowly warm to start the week,
but should remain near normal rather than jump back above.
&&
.Aviation...(06Z TAF Issuance)
Issued at 1122 PM EDT Thu May 27 2021
IMPACTS:
- VFR CIGS are expected to deteriorate to MVFR/IFR after 12Z.
- TSRA possible...but coverage and confidence too low for a mention
at this time.
DISCUSSION: Radar shows new convection developing across Illinois
along the warm frontal boundary ahead of the deer upper trough
pushing out of the northern plains. HRRR propagates these showers
across Central Indiana through night...with hit and miss type
coverage. Favorable moisture remains in place for showers but
instability appear lacking for any TSRA. Thus have trended toward
VCSH and SHRA through much of the TAF period.
Forecast soundings and time heights continue to show saturated lower
levels through Friday morning as the upper wave continues to provide
broad forcing as it heads toward and passes across Indiana. Thus
will trend to VCSH with MVFR/IFR Cigs as these features pass through
the morning hours.
Some improvement should be seen through the afternoon and into the
evening as the upper wave exits and subsidence is depicted within
the mid and upper levels through Friday afternoon.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...Puma
Short Term...Nield
Long Term...CP
Aviation...JP
Area Forecast Discussion
National Weather Service Midland/Odessa TX
621 PM CDT Thu May 27 2021
.DISCUSSION...
See 00Z aviation discussion below.
&&
.AVIATION...
Winds the next couple of hours may be erratic due to an outflow
boundary moving into the northern Permian Basin. Afterward
south to southeast winds will affect all TAF sites through at
least 12Z. At that time a weak cold front will shift winds at
MAF/HOB to a more easterly direction. MVFR CIGs may also develop
behind the front but confidence is not high enough to include in
the TAFs at this time.
Hennig
&&
.PREV DISCUSSION... /issued 245 PM CDT Thu May 27 2021/
DISCUSSION...
KMAF 12Z RAOB shows a cap similar to 24 hours ago, but mesoanalysis
shows it eroding NW-SE, despite a subtropical fetch of hi-lvl
moisture retarding diurnal heating. Vis sat imagery shows cu
developing Davis Mtns/Stockton Plateau, w/the HRRR developing the
Pecos County supercell after 19Z. Sfc obs at 18Z show the dryline
extending from KHOB to KPRS, w/a dewpoint at KMAF of 66F. After the
Pecos Co. supercell develops, other convection is expected to
initiate on the dryline north and south. Steep mid-lvl lapse rates
in excess of 7C/km will favor large hail, and damaging winds will be
possible as well. This activity could merge w/a MCS expected to
develop over OK and move southward overnight, but this looks to
happen just NE of the CWA.
Friday, easterly upslope flow will drive the dryline into far west
Texas, w/initiation farther west over the higher terrain than today.
A cold front will approach from the north, although the NAM has
slowed it somewhat from previous runs. Regardless, the CWA will
spend the day in the warm sector, w/mlcapes in excess of 2500 J/kg
east of the dryline. Steep mid-lvl lapse rates and dcapes also in
excess of 2500 J/kg on the higher terrain will again favor big hail
and damaging winds for much of the area. Both the NAM and GFS are
similar in developing a MCS and clipping the NE zones Friday night.
Saturday, the dryline remains west of the area, and will continue to
be the focus for severe activity during the afternoon and evening,
although models suggest activity will not be as widespread as
today/Friday.
Sunday, the west coast upper trough will dig to Baja del Norte/NW
Sonora, and send a strong shortwave through West Texas and Southeast
New Mexico w/long range models suggesting the best chances of rain
this forecast, especially Sunday night. Of course, severe wx
remains a possibility.
For the rest of the work week, the trough opens and parks over
northern Mexico, sending plenty of disturbances through SW flow
aloft for at least isolated chances of convection daily. We need to
cram in as much rain as possible this week and next, as the
extended GFS hints at the arrival of the summertime ridge.
For temperatures, it looks like we`ll finish the month w/out KMAF
reaching triple digits. Temps look to stay well-below normal into
the extended, and highs may struggle to get out of the 70s NE zones
Mon/Tue.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 66 84 63 81 / 40 40 50 20
Carlsbad 66 92 65 85 / 0 10 10 10
Dryden 71 89 69 88 / 40 20 20 20
Fort Stockton 68 91 66 88 / 30 20 20 10
Guadalupe Pass 64 89 60 84 / 0 0 10 20
Hobbs 64 83 61 80 / 10 30 30 20
Marfa 60 93 60 89 / 10 20 10 20
Midland Intl Airport 66 87 63 83 / 30 40 40 20
Odessa 66 87 64 83 / 20 40 40 20
Wink 66 93 65 88 / 10 20 20 10
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
99/99/10
Area Forecast Discussion...UPDATED
National Weather Service Memphis TN
933 PM CDT Thu May 27 2021
.UPDATE...
Initial round of storms moved into northeast AR and the MO
bootheel earlier this evening, and continued into west TN, mainly
north of I-40. Instability was initially adequate for severe
storms, around 1500 J/KG, but weak bulk shear and shallow midlevel
lapse rates limited storm threat to sub-severe wind gusts and
flash flooding. Last several HRRR runs have depicted storms
weakening further as they move into in area of weaker instability
and stronger convective inhibition. This is consistent with radar
trends over the past hour or two.
Out west, GOES IR imagery showed midevening storms over OK had a
strong southward propagation component. This appeared to less so
with the storms over western AR, as they appeared be more tied to
a westerly midlevel shortwave and synoptic cold front. These
storms will likely arrive to east central AR, the Memphis metro,
and north MS overnight - weakening in the process.
Forecast update remains on track. No severe thunderstorm watches
are anticipated, but gusty winds, heavy rainfall and frequent
lightning will remain possible.
PWB
&&
.PREV DISCUSSION... /issued 702 PM CDT Thu May 27 2021/
UPDATE...
See the 00Z aviation discussion below.
PREV DISCUSSION... /issued 249 PM CDT Thu May 27 2021/
DISCUSSION...
Convection continues to develop across Missouri ahead of a cold
front that stretches across Northern Missouri into Eastern Kansas.
The convection is firing up along an old outflow boundary. Some
additional showers and thunderstorms have developed out ahead of
the line. Expect this trend to continue with isolated/scattered
development occurring across Northeast Arkansas and the Missouri
Bootheel over the next couple of hours. Expect the main line of
convection that is developing across Southern Missouri along the
old outflow boundary to push into Northeast Arkansas by 6-7 PM
CDT. The line is moving into an area of 3000-4000 J/KG of CAPE
that is located over Eastern and Central Arkansas. As a result,
expect the line to begin intensifying over the next couple of
hours. Damaging winds will be the main threat from the storms.
The line will continue to push through the Mid-South over the
course of the rest of the evening into the overnight hours. The
line will likely weaken by the overnight hours. The remnants will
work the atmosphere over for Friday as the cold front moves into
the region except for portions of Northeast Mississippi.
Redevelopment may begin around noon time across areas along and
southeast of a Iuka to Tupelo to Calhoun City line. Some of these
storms may become severe, but the risk will only last a couple of
hours as convection will quickly push to the southeast. Otherwise,
a few lingering showers may occur behind the front. Temperatures
will be cooler behind the front with highs in the mid to upper
70s.
High pressure will begin to settle over the Ohio Valley by Friday
Night and will remain in place throughout the holiday weekend.
Expect beautiful conditions with cool temperatures and low
humidity. Temperatures may begin warming by late in the weekend
into Memorial Day as upper ridging begins to occur over the area.
Expect highs to range from the mid 60s to the mid 70s Saturday and
Sunday. Lows will be in the mid 40s to mid 50s.
An upper level low will begin to move into the Central and
Southern Plains by the middle of next week. Disturbances will
rotate around the upper low setting off showers and thunderstorms.
Models continue to disagree on timing, but Wednesday afternoon
through Thursday will likely be the best chances for rain.
KRM
&&
.AVIATION...
/00Z TAFs/
First line of storms is currently affecting JBR and slowly moving
east northeast. This line is expected to build back to the
southwest and push into MEM and MKL around 28/06Z. Kept a VCTS at
MEM in the short term to account for activity nearby. Went with
tempo groups to account and time the wind shift at MEM around the
push. Wind gusts may approach 35 kts with the line of storms.
Trailing SHRAs can be expected through early morning,
before tapering off by late morning. Expect VFR conds to fall to
MVFR/IFR with the heaviest SHRAs overnight, with MVFR/IFR CIGs
hanging around through tomorrow morning. Winds will shift to the
northwest tomorrow afternoon behind a cold front. Expect a few
gusts to 20 kts and VFR conds through the end of the period.
AC3
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&
$$
Area Forecast Discussion
National Weather Service Phoenix AZ
451 PM MST Thu May 27 2021
.UPDATE...
Updated 00Z aviation discussion.
&&
.SYNOPSIS...
Expect mostly clear skies the next several days along with
seasonably warm high temperatures. A warming trend by the middle of
next week will support the warmest highs by next Thursday of 103-104
degrees for Phoenix. A slight chance of thunderstorms or dry
lightning is also possible, mainly for high-terrain areas east of
Globe for the first half of next week. Also some occasional
seasonably breezy conditions are likely but no area-wide strong wind
events are expected.
&&
.DISCUSSION...
Regional upper air RAP and mesoscale analysis reveals dry westerly
flow aloft as well as a weak UL trough and PVA anomaly leaving the
area to the east with an upstream split-flow pattern over the W US.
There was also a shortwave trough entering the PAC NW and a
progressive ridge crossing the N Rockies. Early afternoon METSAT
also revealed clear skies across the region with CU developing
over the higher terrain north of the area. WV imagery and ACARs
soundings also confirmed a swath of drier air crossing the
region.
A warming trend will continue today with highs topping out in
Phoenix several degrees above yesterday`s high in the upper 90s to
100. Today could also mark the first day in a week with above or
equal to normal highs at Sky Harbor. The normal high for today is
99 degrees.
The hot and dry forecast for the Memorial Day Holiday weekend
remains on track with seasonably warm temperatures running
slightly above normal through the middle of next week. Models
agree on dry westerly flow with flattened ridging into saturday,
followed by a weak mostly-dry positively tilted low pressure
system developing over the northern GOC just SW of the region from
Sunday into Monday. As a result expect highs in a fairly narrow
range through the period. Highs will climb to near 100-103 degrees
for Saturday with the weak low allowing for very slight cooling
with highs near 99-101 for Sunday and Memorial day.
By Tuesday the Clusters analysis agrees on building a strong ridge
of high pressure over the W-Cent to NW US with the weak low moving
very little as it fills and weakens over NW MX/N Baja/N GOC. They
also support more pronounced building and strengthening of the
ridge over the W US with only a very slight chance of isolated
high-base thunderstorms for the first half of next week, mainly
over the high terrain areas of N-E-SE AZ. As a result temperatures
could possibly climb to near 103-104 degrees for Phoenix by
midweek and 104-107 out west.
The pattern suggests that if the heat were to get more intense
it would occur mid-late next week when the weakness aloft/weak upper
trough/lower heights exits or fills, and with increased upper
ridging building in from the northwest becoming the dominant
feature. Currently, periods of patchy moderate heat risk developing
and expanding are favored and will require close monitoring.
&&
.AVIATION...Updated at 2351Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT;
Southeast California/Southwest Arizona including KIPL and KBLH:
Minimal aviation impacts are expected through Friday across the
entire region as diurnal winds persist under clear skies and zonal
flow aloft. Westerly 5-10 knot winds at the Phoenix terminals
will become light and variable later this evening. Easterly winds
return between 06-10Z before veering to westerlies between 18-19Z
on Friday. Southerly to westerly 5-15 knot winds will generally
persist across southeast California and southeast Arizona. Brief
15-20 knot gusts will occur at KBLH for through 02Z and again on
Friday afternoon. Downsloping westerlies this evening may also
lead to brief gusts in excess of 15 knots at KIPL as well.
&&
.FIRE WEATHER...
Sunday through Thursday:
Weak upper level troughing will settle in over the region during
the forecast period with high pressure increasing by Wed. Max RH
values go from 25-40% early in the week to 20-30% by Thu. Min RH
values increase as well but remain below 15% (even single digits
for a lot of areas). Max Ts will be seasonable although slightly
above normal with the warmest day being Thursday with highs
102-107 lower deserts (2-5 degree increase from Saturday). There
will be some day to day fluctuation in afternoon breeziness with
Thursday perhaps being a bit breezier than some of the other days.
Overall though, no strong wind events are anticipated.
&&
.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Sawtelle
AVIATION...Hopper
FIRE WEATHER...Sawtelle/AJ
Area Forecast Discussion
National Weather Service Shreveport LA
941 PM CDT Thu May 27 2021
.UPDATE...
As of the 02Z hour, the squall line at the leading edge of the
MCS over Oklahoma is already arriving at the northern edge of
McCurtain county. The system is propagating southward more quickly
than previous model guidance suggested and looks like it will
maintain its forward speed as it enters northeast Texas and
northwest Louisiana. Gusty winds of up to 30-40 mph will be
possible with this line, and an isolated severe threat cannot be
ruled out. Isolated pockets of locally heavy rainfall in already
thoroughly saturated areas will present the possibility of
localized flash flooding.
Thus, PoP grids have been updated to reflect this accelerated
arrival of precip, consistent with the 01Z HRRR run. The leading
edge of the line is on track to arrive in ELD/SHV/TYR by 06Z and
will be exiting our southern regions by 12Z. PoPs will rapidly
fall off in the wake of the frontal passage and remain dry through
Friday, until moisture begins to return to deep east Texas by 00Z
Saturday.
Additionally, adjusted overnight lows down a few degrees to
reflect the southward intrusion of rain cooled air behind the
squall line in the pre-dawn hours.
/26/
&&
.PREV DISCUSSION... /issued 644 PM CDT Thu May 27 2021/
AVIATION...
VFR conditions will continue to prevail across the area in
advance of a line of strong thunderstorms advancing southward
through the region overnight into Friday morning. Between 28/04Z
and 28/10Z, these storms will begin to bring MVFR ceilings and
visibilities to all terminals as they pass from north to south. In
their wake, terminals will see a return to VFR late in the TAF
period. Winds will continue to be southerly to southwesterly in
the neighborhood of 5-10 kts ahead of the line of storms, and will
become variable then northerly after the passage of the front.
/26/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 69 86 66 78 / 80 40 30 20
MLU 69 86 64 76 / 80 40 20 20
DEQ 68 84 59 77 / 80 30 20 10
TXK 69 84 63 76 / 90 40 20 10
ELD 69 84 59 76 / 90 50 20 10
TYR 69 85 66 78 / 90 40 40 30
GGG 69 84 66 77 / 90 40 40 30
LFK 72 86 69 79 / 80 50 50 50
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
26/26
Area Forecast Discussion
National Weather Service San Angelo TX
617 PM CDT Thu May 27 2021
...New AVIATION...
.SHORT TERM...
(This evening through Friday)
Issued at 213 PM CDT Thu May 27 2021
After the brief lull in convection yesterday into this morning,
strong to severe storms expected this evening and continue into
Friday. Moist and unstable air mass remains in place, with
temperatures climbing well into the 80s. Dewpoints are in the low
to mid 60s, with near 70 dewpoints lurking not very far away.
For tonight, shortwave moves into West Texas and enhances the mid
level flow. CAMS all show convection developing across the Trans
Pecos and then between Midland and Lubbock with activity moving
east. Trans Pecos activity may survive into Crockett County and
perhaps into irion, Schleicher, and Sutton before gradually
weakening later in the evening. Convection farther north will move
into the western Big Country, perhaps developing into a MCS and
moving across the remainder of the Big Country by midnight. Wind
and hail the main threats (perhaps high end hail and wind), but
decent helicity in that area around near Sweetwater early this
evening will mean a tornado threat as well.
Convection eventually dissipates overnight, leaving an outflow
boundary draped across the area. Additional outflow and a weak
cold front across Oklahoma overnight will push south as well on
Friday. By Friday afternoon, air mass remains unstable and with
surface boundaries across the area. Weak ridging aloft behind the
shortwave tonight will make for weak mid level flow, but HRRR and
NAMNEST still are aggressive in producing strong convection by
mid/late afternoon somewhere near Abilene/San Angelo/Brownwood and
dropping it southeast across the remainder of the area. Given CAPE
values pushing 4000+ and boundaries to provide some focus, going
to go with the CAMS models and bump POPs for Friday afternoon.
&&
.LONG TERM...
(Friday night through next Thursday)
Issued at 204 PM CDT Thu May 27 2021
A very active pattern will continue for this weekend as ongoing
strong to severe thunderstorms on Friday night will at least linger
into Saturday morning. Northwest flow aloft combined with a cold
front and any outflow boundaries will likely result in shower and
thunderstorm redevelopment during the day Saturday. A weak 500mb
ridge will try to build in Saturday night, allowing for a brief
reprieve. But as a new trough digs in over the Desert Southwest,
the upper levels will transition back to a westerly to southwesterly
flow pattern. This, along with moist surface flow returning from
the southeast will reintroduce high chances for rain and
thunderstorms for late Sunday through Monday. In addition to the
usual damaging wind and hail threat, several inches of rain will be
possible with this activity. The 12Z run of the GFS is currently
pegging 4-6 inches of cumulative rainfall by early next week,
including whatever occurs on Friday. Without sufficient drainage
between rounds of convection, this could lead to flooding concerns.
For the middle of next week, a trough starts to dig southward out of
Canada, pitting the trough axis over the central and southern
Plains. This should further enhance the dynamics, allowing for even
more rounds of rain and thunderstorms for Tuesday through Thursday.
Otherwise, high temperatures this weekend through the middle of next
week look to be a few degrees cooler than normal, while nights will
be very mild and humid.
&&
.AVIATION...
(00Z TAFS)
Issued at 616 PM CDT Thu May 27 2021
Scattered thunderstorms across the Permian Basin will move east
and may impact the KABI terminal this evening, mainly 02-05Z.
Also, going with a VCTS at the KSJT site this evening but
confidence is low. Otherwise going VFR for the next several hours,
then MVFR ceilings will return Friday morning to the terminals,
mainly between 12-18Z.
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 67 83 63 79 / 60 60 40 30
San Angelo 69 88 64 85 / 30 60 40 20
Junction 71 88 66 86 / 10 50 40 30
Brownwood 69 84 65 80 / 30 60 50 30
Sweetwater 66 81 63 79 / 60 60 40 20
Ozona 71 88 66 86 / 30 50 40 20
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SHORT TERM...07
LONG TERM....SK
AVIATION...21
...Update to aviation forecast discussion...
.DISCUSSION...
Issued at 324 PM CDT Thu May 27 2021
Latest surface analysis had the cold front extending from north of
MCI to TOP southwest to near ICT at 20Z. HRRR has been doing okay with
the southeast progression of the front through the rest of the
afternoon into the evening hours. Have kept higher pops going for
areas southeast of the front. Anvil cirrus from convection in
northern Oklahoma has kept the stronger instability from being
realized. Still could see an isolated strong to severe storm through
the rest of the afternoon into early evening, but confidence is low.
Will continue with the Flash Flood Watch through the rest of the
afternoon as some areas will not need much additional rainfall to
cause flooding. For tonight expect the front to move south of the
area as the mid level trough moves eastward across the Plains.
Cooler temperatures will filter southward with lows falling to the
40s to low 50s.
A rather large area of clouds across the Dakotas and Nebraska will
move southward tonight and expect extensive cloud cover over the
area on Friday. High pressure will build into northeast Kansas on
Friday and remain over the area on Saturday keeping temperatures
cool and dry conditions. Upslope flow into the high Plains and
Rockies and a mid level wave moving out of the Rockies will cause
convection to develop and then propagate southeast into central and
parts of north central Kansas early Sunday morning. The mid level
wave will continue east through eastern Kansas on Sunday with
chances of showers and a few thunderstorms over the area.
Memorial Day through Wednesday a trough will be present out west
with energy moving out across the central and southern Plains
bringing a continued chance of showers and storms. By mid week a
long wave trough is forecast to move through bringing an end to
precipitation chances later on Thursday. Cooler temperatures are
expected from Sunday through mid week with highs in the 60s Sunday
and Memorial Day then low to mid 70s for the rest of the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 624 PM CDT Thu May 27 2021
Edge of the VFR stratus behind the departing front is between
KMHK and KTOP/KFOE with gradual clearing within the next few
hours. Short term soundings are consistent in MVFR stratus
dropping south from eastern NE aft 05Z and settling into the
region through early afternoon. Some indication that the cloud
thicknesses thin with VFR returning by the end of the period.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch until 7 PM CDT this evening for KSZ040-054>056-
058-059.
&&
$$
DISCUSSION...53
AVIATION...22