Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/24/20
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
523 PM MDT Thu Apr 23 2020
00Z TAF CYCLE
Windy/gusty northwest flow will persist into the early evening
hours, relax, then mix back down to the surface Friday mid morning.
A few virga showers across north central and northeast NM this
evening will be associated with strong/erratic wind gusts and may
come close to KLVS and KTCC. Otherwise, VFR conditions prevail and
are forecast to persist.
.PREV DISCUSSION...247 PM MDT Thu Apr 23 2020...
The warming continues today, with breezy to windy conditions
prevailing. A weak cold front will move through overnight and
provide a couple degrees of cooling going into Friday, with more
breezy to windy conditions expected by afternoon. Look for a warming
trend over the weekend and into early next week, although a backdoor
cold front will move down the eastern plains Friday night into
Saturday and provide several degrees of cooling. Temperatures will be
above normal areawide by Sunday, then rise to challenge daily record
highs for Monday and Tuesday of next week. Another backdoor cold
front will cool down the eastern half of the state on Wednesday, with
even warmer temperatures forecast to end the work week.
SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)...
Water vapor imagery and GOES high density winds still show a strong
jet core approaching NM from the northwest this afternoon. Surface
winds have been slow to increase across the region with thicker mid
level clouds developing over much of northern NM. The 20Z LAVMOS is
still in line with a punch of stronger west-northwest winds aft 22Z
at several sites however confidence is decreasing given latest obs,
lighter 12Z METMOS trends, and weaker mid level winds on latest RAP
bufr profiles. Nonetheless, will continue the Wind Advisory however
an early cancellation is entirely possible.
A deeper dry airmass will shift through northern NM Friday in the
wake of the departing upper jet axis. This will continue the threat
for strong northwest winds in the corridor from near KFMN to KABQ
and KCQC. Guidance trended winds lighter for Friday however given
the slower increase in winds today it`s possible winds will trend
stronger again Friday. A back door cold front will also move thru
eastern NM with a northerly wind shift, slightly higher humidity,
and cooler temps. Winds are likely to decrease quickly on Friday
evening as surface high pressure builds over the state. Stronger
radiational cooling will trend low temps closer to normal for late
LONG TERM...(SATURDAY THROUGH THURSDAY)...
A weak shortwave trough embedded in northwest flow aloft will eject
out of the southern Rockies Saturday and may generate a few showers
or storms across the northeast plains/highlands. Otherwise, breezy
to locally windy conditions are forecast Saturday, with continued
warming across western NM. Dry westerlies will penetrate further east
across the state Sunday, leading to continued warming and above
normal temperatures areawide. Winds aloft begin to relax Monday and
pressure heights increase further, allowing for more warming with
temperatures approaching daily record highs at a few sites. An upper
level ridge will build Monday night into Tuesday along the west coast
and begin shifting east across the Intermountain West. Tuesday
should be even warmer, with a number of sites potentially challenging
daily record highs. A backdoor cold front will slide down the
eastern plains Tuesday evening and provide several degrees of
cooling going into Wednesday across eastern NM. Temperatures will
bounce back up Thursday as the upper level ridge axis shifts
...RED FLAG WARNING IN EFFECT UNTIL 7 PM MDT THIS EVENING IN CENTRAL
AND EAST CENTRAL NEW MEXICO DUE TO STRONG WINDS AND LOW HUMIDITIES...
Critical conditions are slow to develop today with widespread cloud
cover developing along the northern flank of the Red Flag Warning.
Winds are still likely to increase through late day however the I-40
corridor may only see marginal conditions today. A stronger pressure
gradient on Friday with lower RH will lead to another few hours of
marginal critical fire weather but temps will be cooler and Haines
indices are still low to moderate. Confidence is not high enough for
a Fire Wx Watch at this time for Friday. A back door cold front will
move through eastern NM late tonight and Friday with cooler temps
and higher RH for the eastern plains.
The weekend will feature a slow warming trend with northwest flow
gradually easing over the state. A couple northeast wind shifts will
dip into far northeast NM with perhaps a few showers and storms near
the CO border Saturday and Sunday.
A significant warming trend with near record heat is on the way for
next week as a strong upper level ridge builds west of NM. Min RH
will be very low beneath the ridge which leads to large diurnal
temperature swings and lighter winds each day. There are hints at a
moist back door front Wednesday night or Thursday for eastern NM.
Red Flag Warning until 7 PM MDT this evening for the following
Wind Advisory until 8 PM MDT this evening for the following zones...
Area Forecast Discussion
National Weather Service Burlington VT
1044 PM EDT Thu Apr 23 2020
After a sunny but cool day across the North Country, rain and snow
chances will move into southern Vermont toward daybreak on Friday.
Any precipitation that is observed will be light and will exit the
region by Friday afternoon. Drier and near normal temperatures
are expected on Saturday before the next system swings through
the North Country on Sunday. Cooler and unsettled weather will
develop across the region early next week before another storm
system approached the region during the middle of next week.
.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 1040 PM EDT Thursday...Latest HRRR and 00Z NAM have
trended further south with northern fringe of precipitation late
tonight into Friday morning. As a result, have lowered PoPs to
just 30-40% across s-central VT, with mention of just light
rain and higher elevation snow possible. Any higher elevation
snow accumulation is expected to be 0.5" or less. Still appears
that thicker cloud cover will keep temperatures cooler across
s-central VT for Friday afternoon (around 50F) while temperatures
warm into the mid 50s for the valleys of northern VT and far nrn
NY. Previous discussion follows.
Winds are diminishing across the North Country this evening
with onset of diurnal cooling cycle. We observed a seasonably
cool but sunny day with a ridge of high pressure across northern
NY and VT. Satellite imagery at 23Z shows a very distinct line
of clouds across central New York and extending eastward into
Massachusetts. Based on surface observations, this appears to be
a weak warm front with radar showing some light rainfall
associated with this boundary. Northward progression is being
stifled by the drier air currently in place across the North
Country. This will change after dark as portions of southern
Vermont begin to see an influx of moisture which will allow for
some light precipitation to begin falling across Rutland and
Windsor counties around daybreak on Friday. Temperatures
initially will be cold enough to support snow where
precipitation works into southern Vermont and given the amount
of dry air in place increasing wet bulb potential, we should see
more snow than rain even as temperatures begin to warm after
sunrise on Friday.
A low pressure system over the Mid-Atlantic region will move south
of the area during the day on Friday but a triple point low
developing off the New England coastline will steal the energy from
this system as it quickly moves northeast. With the newly formed
triple point low, any semblance of a moisture feed will get quickly
shut off and precipitation chances will quickly taper off as we head
into the afternoon hours. When all is said and done less than a half
of an inch of snow is expected across Rutland and Windsor with up to
a tenth of an inch of QPF. Elsewhere, mid to high level clouds will
prevail but should be a nice day overall with temperatures warming
into the lower to mid 50s. High pressure will begin building back
into the region Friday night which will allow for a gradual clearing
trend through the overnight hours.
.SHORT TERM /SATURDAY THROUGH MONDAY/...
As of 339 PM EDT Thursday...Best day of the weekend still appears to
be Saturday as surface high pressure over Ontario and Quebec eases
southward over the North Country while an upper ridge amplifies
slightly over the Northeast ahead of a shortwave trough and
developing surface low digging into the Ohio Valley. The morning
should begin relatively cloud free, with increasing mid/high clouds
expected through the afternoon and temps warming nicely into the
mid/upper 50s. Saturday night remains dry as well, but with
thickening and lower mid clouds think temps won`t be as chilly as
previous nights with lows in the mid/upper 30s to locally lower 40s
in the St. Lawrence Valley.
Active weather looks to return for Sunday and Monday but the jury
remains out on exactly how much valley rain and mountain snow
showers we see. I`m calling todays 12Z deterministic guidance "USA
vs. World" as the main regional/global models of the NAM/GFS are
completely at odds with the ECMWF/GEM. The main impetus behind the
uncertainty will be 1) where low pressure pulling eastward out of
the Ohio Valley tracks, and 2) the strength and southward extent of
high pressure centered over James Bay. In general, all of the
guidance shows a mean storm track of the primary low into the mid-
Atlantic states Sunday afternoon with an energy transfer to a
secondary low developing along the coast Sunday night. The
differences really lie with high pressure to the north, where the
NAM/GFS solutions are weaker and further north than the ECMWF/GEM
which will play a large role as to where a sharp cutoff in precip
occurs. Not wanting to play favorites, and given little run to run
consistency between all these models I`m offering a blended PoP
forecast with Sunday beginning dry, then trending to high chance to
likely by the afternoon with the highest chances across our
central/southern zones through Sunday night.
Showers look to linger into Monday, at least through mid-day with
temps struggling through the 40s given precip and cloud cover.
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
As of 339 PM EDT Thursday...Looking out towards the middle of next
week, while Tuesday still appears to be cool and dry with temps in
the low 50s, there remains little agreement amongst global models in
the timing and track of our next system on schedule for Wednesday or
Thursday. While the ECMWF and GEM offer glimmers of hope that an
upper ridge will amplify over the eastern seaboard and keep the
forecast area dry, the GFS breaks the Tuesday ridge down rather
quickly into another broad upper trough and offer more
precipitation. For now, will offer some chance PoPs with temps near
normal in the 50s for highs and 30s/40s for lows.
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Through 00Z Saturday...Primarily VFR conditions continuing
during the next 24 hours, except for possible MVFR at RUT in
12Z-18Z period. Based on some high-resolution model guidance,
RUT is likely to see a period of stratiform rain, which could
possibly mix with snow, that may lower cloud bases lower than
currently forecast. That rain will be associated with a synoptic
scale system to the south, promoting changing but light surface
winds, except channeling north winds around 10 kts during the
afternoon at PBG and BTV and northeast winds peaking in the
10-15 kts range at MSS from 12Z to 18Z.
Friday Night: VFR. NO SIG WX.
Saturday: VFR. NO SIG WX.
Saturday Night: VFR. Chance SHRA.
Sunday: Mainly VFR, with local MVFR possible. Chance SHRA.
Sunday Night: Mainly VFR, with areas MVFR possible. Chance SHRA.
Monday: Mainly MVFR, with areas VFR possible. Chance SHRA.
Monday Night: Mainly VFR, with areas MVFR possible. Slight chance
Tuesday: Mainly VFR, with local MVFR possible. NO SIG WX.
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
749 PM CDT Thu Apr 23 2020
Small update to increase mention of fog tonight into Friday
morning throughout the Coastal Bend and nearshore waters. Very
moist easterly flow with dewpoints in the lower 70s was about
15-20 miles offshore this evening, and radar was sampling a fine
line in this same area. Recent SREF and to a lesser extent the
HRRR are trending more bullish with fog after midnight, and this
pattern shows some similarities to this past Monday morning`s fog
event. Would expect some dense fog to develop eventually, but for
now we`ll monitor trends and adjust the forecast accordingly.
.PREV DISCUSSION... /Issued 322 PM CDT Thu Apr 23 2020/
SHORT TERM (Tonight through Friday night)...
Clearing skies and drier air has filtered in across the area behind
a frontal passage this morning. Winds from the north have begun to
shift east and will shift south/southeast as low pressure to the
north continues to push east. The weak onshore flow will increase
low level moisture overnight tonight, providing some possibility for
patchy fog across the Coastal Plains around sunrise. Any fog will
quickly lift as the daytime heating begins. Temperatures will be
quite warm tomorrow with highs from the mid 80s near the coast to
around 100 degrees across the Brush Country. RH values will be quite
low across the Brush Country Friday afternoon, but winds will
remain low keeping fire weather conditions limited. Another weak
cold front will cross the area Friday night, with north to
northeasterly winds returning.
LONG TERM (Saturday through Thursday)...
Slightly cooler temperatures Sat in the wake of a weak cold front.
However, temps will still be above normal with a subsident northwest
flow aloft. This will also lead to mostly sunny skies Saturday. At
the surface, high pressure will shift east leading to a weak to
moderate easterly flow across S TX. Another weak surge of high
pressure will result in winds backing to the northeast Saturday
night, then becoming southeast once again by Sunday afternoon.
Lack of moisture, no forcing and a capping inversion will keep
precip out of the forecast through the weekend and into Monday. The
onshore flow will gradually warm temperatures and increase moisture
the first part of next week. Instability, a weakening cap and a
short wave aloft will bring a slight chance of convection by
A weak to moderate east to northeast flow over the coastal waters
may lead to some minor coastal flooding during times of high tide
through the weekend.
Very low RH values are expected through the weekend. However, 20ft
winds are expected to be rather light, thus no fire weather concerns
Light to moderate onshore flow across the waters today will continue
through Friday night. Patchy sea fog is possible tonight and into
the early morning hours Friday. A weak to moderate northeast to
east flow is expected Saturday. Winds will become moderate
Saturday night into Sunday morning across the coastal waters. A
weak to moderate southeast flow will return by Sunday night and
continue into Monday. The onshore flow will strengthen once again
to moderate levels by Monday night into Tuesday. Precipitation is
not anticipated through Monday. A slight chance of showers and
thunderstorms will be possible by Wednesday.
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 68 94 71 84 66 / 0 0 0 0 10
Victoria 64 92 66 85 60 / 0 0 0 0 10
Laredo 69 102 72 92 67 / 0 0 0 0 10
Alice 65 101 69 89 63 / 0 0 0 0 10
Rockport 67 83 73 82 67 / 0 0 0 0 10
Cotulla 65 101 68 91 62 / 0 0 0 0 10
Kingsville 65 99 71 88 65 / 0 0 0 0 10
Navy Corpus 70 82 73 81 70 / 0 0 0 0 10
Area Forecast Discussion
National Weather Service Grand Forks ND
1006 PM CDT Thu Apr 23 2020
Issued at 1004 PM CDT Thu Apr 23 2020
Showers continue to wane. A few left in WC MN and one near DVL.
Will mention isold shower overnight DVL region and thru SE ND/WC
MN. Few showers in SW MB moving southeast just east of the next
500 mb shortwave entering NW ND. But cooling of the night limiting
activity with this next short wave. Other than tweeks to sky and
pops no signifcant changes.
.SHORT TERM...(This evening through Friday night)
Issued at 334 PM CDT Thu Apr 23 2020
Mid level shortwave trough is activity passing over our CWA, but
trough has remained broad/positively titled with less
apparent/organized forcing. Still, there is some forcing that may
combine with the steep low level lapse rates in place across our
region to support increasing shower coverage (isolated thunderstorms
with MUCAPE already 500 J/KG according to SPC RAP mesoanalysis).
Regional radar trends show the increasing coverage to our west,
while it remains a bit more isolated locally. Expect best coverage
pre-sunset with loss of coverage/intensity following diurnal cycle
as mid level lapse rates remain below 6 C/km.
We could still see a repeat of this same pattern Friday afternoon-
Friday night with daytime destabilization and weak shortwave passage
within northwest flow aloft. Seasonably mild temperatures again
Friday, with many locations over 60F again.
Regarding precip amounts/impacts: Still expect most locations that
have showers to only a few hundredths to around 0.1", but where
thunderstorms track or showers backbuild there is potential for 0.25-
0.5" over very small/localized areas based on HREF max potential
.LONG TERM...(Saturday through Thursday)
Issued at 334 PM CDT Thu Apr 23 2020
Split flow regime is still on track for the near future which will
continue to keep most of the moisture and heavier action well south
of our forecast area.
Chances for impactful weather will be minimal, northwest flow will
see a weak shortwave traverse through on Sat. So although there may
be numerous showers hitting a good part of the area (mainly liquid)
during this time it is not likely to amount to much.
A better chance for at least several tenths of pcpn will present
early next week as the flow shifts a little more zonal, perhaps
allowing more Pacific moisture to enter the picture.
Temperatures will be holding close to seasonal averages through the
beginning of next week, with highs from the upper 50s to low 60s,
and lows remaining above freezing.
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 703 PM CDT Thu Apr 23 2020
VFR thru the period. Cloud bases in the 7000-10k ft range in the
scattered to broken coverage range. Winds light, under 10 kts thru
Friday, mostly northerly direction.
River point flood warnings continue across portions of
the region. Refer to the latest flood warnings and statements for
detailed information on specific locations.
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
702 PM CDT Thu Apr 23 2020
.SHORT TERM...(This evening through Friday)
Issued at 317 PM CDT Thu Apr 23 2020
We have a weak shortwave trough moving through the area within a
northwesterly flow pattern. Dewpoints are low and only in the 30s
for most areas so we don`t have much moisture to work with.
Afternoon heating up to our convective temperatures is allowing
popcorn variety showers to form and with limited instability there
could be a few weak thunderstorms. The instability SBCAPE values
are only around 500-800 J/KG with 0-6 km shear 30 kts at best.
Therefore, even though some thunderstorms will be possible with
perhaps a strong storm or two, severe thunderstorms continue to
This evening through tonight...
Forecast models such as the NAM and HRRR have been indicating that
showers and isolated thunderstorms could linger for awhile this
evening before a bit of a lull around midnight through 4 am.
However, there is the possibility that we could see a little
uptick in rain shower activity near dawn, but nothing too
widespread, so will keep chances low.
We will see northerly flow and cooler conditions behind the trough
axis. There will still be just a little bit of instability around
with the cooler air aloft and some forecast models are giving us a
slight chance for a few showers or thunderstorms, but this really
seems like a 20 percent chance at best and could see these chances
being removed once certainty grows as we get closer. Overall
most areas will likely be dry tomorrow. Highs should be at least
10 degrees cooler and only in the 60s.
.LONG TERM...(Friday night through Thursday)
Issued at 317 PM CDT Thu Apr 23 2020
Overall this should be a rather dry and mild period with
temperatures finally above freezing for a solid run of days right
through the end of the forecast period.
We expect northwesterly flow aloft this weekend, which should be
dry. A little shortwave trough will enter our area Monday and
could bring some showers/thunderstorms Monday night and then we
generally see upper level ridging the rest of the work week.
Saturday could still be cool in the 60s, but then we should warm
up to 70s and even low 80s after that. Tuesday could end up a bit
cooler than currently forecast depending on how much cool air the
Monday night system brings down with it.
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday)
Issued at 659 PM CDT Thu Apr 23 2020
Showers and a few thunderstorms are possible on and off through
the period. Winds will diminish as the sun goes down this evening
and pick up again from the north during the day Friday.
AREA FORECAST DISCUSSION
National Weather Service Morristown TN
829 PM EDT Thu Apr 23 2020
Mountain Wave Winds:
Allowed the High Wind Warning for the East TN mountain zones
above 2500 feet to expire as scheduled, but replaced it with a
Wind Advisory through 06Z. Observations at Cove Mountain, Camp
Creek, and Clingman`s Dome over the past few hours have shown a
diminishing trend with most gusts in the 40-50 mph range. Expect
this trend to continue over the next few hours with 850 mb flow
turning more WSW, however, as the main H5 shortwave and surface
low lift NE into the OH valley, an 850 mb jet will continue in the
vicinity of the southern Appalachians in the 35-45 kt range ahead
of the cold front. Once this front passes after 06Z, the upper
and low-level jet dynamics will move away allowing the winds to
drop below advisory criteria.
The severe threat has ended for the evening. The first line of
showers/storms continues to move off to the NE while weakening as
it moves into much lower overall instability well N of the warm
front. A second line is currently moving across middle TN along
the trailing cold front. Isolated pea sized hail and gusty winds
are possible with this activity between 02 and 04Z, especially
west of I-75, but an overall lack of surface based instability,
convective overturning, and nocturnal cooling will cause this
round to weaken too despite the continued presence of 40-55 kt 0-6
Km shear and 20-25 kt 0-1 Km shear. Updated pops to show a quicker
reduction in the highest coverage from W to E as this secondary
wave moves through. Most pops will be in the chance range after
06Z, except for some pockets of likely pops lingering through 12Z
in far East TN and southwest VA. The rest of the forecast remains
00Z TAF DISCUSSION.
Tricky TAF forecast with low to medium confidence. Scatterd Showers
and a few rumbles of thunder will produce brief heavy rain over
the TAF sites through late evening. Exact timing is the lowest
confidence, but believe these are most likely between now and 04Z
causing brief reductions to MVFR cigs and vis. CHA will be dry
after 04Z, but scattered showers will persist around TYS and TRI
through 09Z. MVFR, and occasional IFR cigs, look to dominate from
the second half of tonight through at least mid morning before
improving to VFR Friday afternoon.
/ISSUED 323 PM EDT Thu Apr 23 2020/
SHORT TERM...(Tonight and Friday)...Afternoon water vapor
imagery continues to show a nearly vertically stacked low moving
into the Ohio river valley with an impressive jet streak aligned
across the Tennessee valley. Water vapor imagery also places a dry
intrusion from the southern plains northeast into Middle
Tennessee. At the surface, an area of low pressure was noted
across northwest Tennessee. Attendant this low was a developing
occluded front from the surface low to south of KMEM. A warm front
was noted from the triple point in northern Mississippi and
stretched southeast into western Alabama and central Georgia. The
airmass across the region continues to remain stable as indicated
by SPC mesoanalysis and 16Z soundings from northern Alabama
confirm this with an strong inversion near 850mb. However some
airmass recovery may be taking place further west.
Regional radar imagery indicates a mostly dry forecast area
currently with some light QPF across southwest Virginia
associated with the left exit region of the upper level jet.
Further west, radar is starting to reveal some weak returns across
West and Middle Tennessee near the occlusion. Cloud Phase
Distinction imagery shows that most of this activity remains low
topped although some vertical development can be seen in an area
that is becoming more unstable. The main question continues to be
to what extend thunderstorms can develop and how strong to severe
those storms will be. Confidence has increased that the threat has
actually lowered with the Day 1 slight risk moved further south
on the mid day update. This places much of the forecast in a
marginal risk while southeast Tennessee remains in an enhanced
risk. While we still anticipate at least some development this
afternoon near the occluded front, CAM data such as the NAMNEST
and HRRR depict this activity to remain isolated to scattered. The
parameter space remains at least marginally conducive for strong
thunderstorms. Overall instability is on the weak side with only a
couple hundred Joules of most unstable CAPE showing up on
mesoanalysis. The surface warm front will remain key as to how far
north the main severe threat will end up. Morning convection
along with current convection across the Gulf Coast has kept much
of the moisture advection at bay with the warm front struggling to
move north. Expect this trend to continue through the afternoon
but it is possible this warm front touches a county or two in
southeast Tennessee. However, there is strong consensus that much
of the surface based instability remains to the south of the
Any tornado threat today will occur near or south of the warm front.
Even then, the tornado threat likely will remain on the low side as
the 850mb jet core begins to eject north and east taking the better
shear with it. However, 0-6km bulk shear of >40 kts does support
some organized convection although most of this activity should
remain elevated. With the elevated nature expected, the main
threats would be convective downdrafts with damaging winds. Some
small hail is also possible as the core of the upper low moves
closer to the region increasing mid level lapse rates. This
activity will move out of the area later tonight. The mountain
wave event continues this afternoon with observations continuing
to indicate high winds. The NPW will continue as a result and
should expire at 00Z.
The forecast for Friday looks much drier especially after the
morning as the upper level low kicks off to the east and surface
high pressure is able to move in. Temperatures on Friday will be
in the lower 60s to low 70s.
Long Term...(Friday Night through Thursday)...
For the extended period, the pattern will remain active under an
amplified pattern typical of the Spring season. There are two main
systems that look to impact the area-one during the Saturday/Sunday
time frame with convective potential and one during the
Tuesday/Wednesday time frame. Aside from rainfall within these
systems, gusty winds for the weekend and below normal temperatures
under largely negative 500mb height anomalies are two other
characteristics that occur within the period.
Friday Night through Monday
The period commences with an approaching surface low from the
Texas/Oklahoma/Arkansas area on Friday with increasing upper-level
support. A longwave trough with an axis in the central U.S. will
shift east during the weekend bringing an 80 to 100 knot 300mb and
500mb jet streak at its base over Georgia and Alabama into Saturday.
This placement puts the County Warning Area in the left-exit region,
which would support upper-level divergence. Accordingly, model
guidance brings a large area of PVA in our region up towards the
Ohio River Valley. These dynamics could help to support convergence
at the surface with the surface warm front being the lifting
mechanism. However, the surface low looks to undergo occlusion
closer to its center, which will work to inhibit severe potential.
Nevertheless, the aforementioned dynamics combined with a 30 to 40
knot 850mb jet will help to keep breezy conditions through Saturday
with some convection still taking place due to instability evidenced
with negative LI values and mid-level lapse rates of 6 to 7 degrees
Celsius/km. While a strong/severe storm or two is still possible,
the threat for significant severe weather remains low.
Heading into Sunday, the low continues off to the northeast with the
upper-level trough deepening from the Ohio River Valley down towards
the Gulf. Wraparound moisture from the low will keep chance PoPs in
the area for Sunday. With 500mb height anomalies approaching -15
dam, anomalously cool temperatures will also be notable on Sunday
with highs struggling to break out of the 50s in most areas, about
15 degrees below normal. Depending on how much clearing takes place
on Sunday night, temperatures could fall into the upper 30s in some
spots. With a surface high and rising heights for Monday,
temperatures do recover mostly into the 60s with dry conditions.
Tuesday through Thursday
For the end of the period, there is increasing confidence for a
large system to develop on the lee side of the Rockies and progress
towards the eastern U.S. Tuesday into Wednesday. There is
significant disagreement in model guidance for track and intensity,
but precipitation sometime in this period looks likely, so PoPs up
to 70% were utilized. With PWAT anomalies per ensemble means within
0.20" of the normal, there is little signal for significant/heavy
rainfall. However, below normal temperatures will likely make a
return by Thursday. This is evidenced by 500mb height anomalies of -
10 to -15 dam with a Phase 3 MJO taking place. This phase is
supportive of below normal temperatures and above normal
precipitation in the March/April/May period in the southeastern U.S.
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 56 74 54 72 51 / 70 10 20 70 30
Knoxville McGhee Tyson Airport, TN 57 71 52 72 51 / 70 20 10 80 40
Oak Ridge, TN 56 71 52 70 49 / 80 20 20 80 40
Tri Cities Airport, TN 54 66 48 69 49 / 70 40 10 80 60
TN...Wind Advisory until 2 AM EDT Friday for Blount Smoky Mountains-
Cocke Smoky Mountains-Johnson-Sevier Smoky Mountains-
Southeast Carter-Southeast Greene-Southeast Monroe-Unicoi.
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
1058 PM CDT Thu Apr 23 2020
(This evening through Friday)
Issued at 248 PM CDT Thu Apr 23 2020
A couple of shortwaves within a northwesterly flow aloft may bring
in some storms off the Central High Plains for the short term of the
forecast. The first is a rather weak wave coming through this
evening. MUCAPE values of 500-1000 J/kg may destabilize the
atmosphere for an isolated thunderstorm or two, but would likely be
more of a light rain event. Latest HRRR guidance remains consistent
with some development beginning across western Oklahoma by late
afternoon while cloud development and mid-level radar echos are
starting to occur. No severe weather is expected if a few of these
storms develop. The second wave coming down from the higher plains
will be a much deeper amplitude trough, developing a surface low
across the Texas Panhandle, which will be moving across Oklahoma on
Friday. Expecting cooler mid-level air to steepen temperatures
lapse rates from west to east with Fridays system, increasing MUCAPE
values up to 3000 J/kg in southeast Oklahoma. Rain could start
developing in more stable air across northwest Oklahoma as a frontal
boundary/cold front moves through, with thunderstorms developing in
destabilizing air across central Oklahoma. Expecting the strongest
vertical ascent across southeast Oklahoma as the left exit region of
an upper jet maxima will be in place there, as well as a fairly
strong low level jet. As a result, southeast Oklahoma has a slight
risk for some severe thunderstorms as a few supercells could develop
late in the afternoon into the evening, with large damaging hail and
60 mph wind gusts as the main hazard. A marginal risk for severe
thunderstorms extends across east central Oklahoma just to the east
of the Oklahoma City metro.
(Friday night through next Wednesday)
Issued at 156 PM CDT Thu Apr 23 2020
Models show generally a NW or WNW flow aloft over the weekend into
next week, with disturbances/shortwaves moving through the flow
which could lead to a chance for showers/storms at times. Figuring
out timing of the disturbances and associated rain chances could be
a bit tricky. Models also show a front moving across the area
Tuesday. The highest chances next week for showers/storms, right
now, look to be Tuesday with this front. Models show an upper trough
digging and moving across the eastern U.S. towards the middle to
late next week. There are some differences on where this digging
begins and how far south it digs. The ECMWF digs the trough over the
Plains with an upper low developing and moving across the Midwest
whereas the GFS begins digging further east across the upper Midwest
with low north of the Great Lakes. If the ECMWF is correct there may
be some upper support in the region with the storms Tuesday where
GFS would have very little upper support. Either way, enough
instability could be around that some strong to severe storms may be
Temperatures are expected to gradually warm over the weekend into
early next week. Generally, near or above average temperatures are
expected across the fa next week.
Issued at 1035 PM CDT Thu Apr 23 2020
Primarily VFR forecast through the period. Strong cold front will
move across the region from west to east late morning and
afternoon tomorrow. While scattered showers are possible across
northern Oklahoma ahead of the front, will focus prob30 TSRA to
possible convection along and just behind front, with associated
MVFR conditions at KPNC. Northwest winds will gust 20 to 30 KT
most sites through much of the day with winds decreasing after
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 57 74 48 70 / 20 30 0 0
Hobart OK 54 75 47 73 / 10 20 0 0
Wichita Falls TX 60 80 50 75 / 0 10 0 0
Gage OK 50 70 43 71 / 10 20 0 10
Ponca City OK 55 71 46 70 / 40 60 10 0
Durant OK 58 82 52 73 / 0 20 10 0