Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/23/17
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
748 PM CDT Mon May 22 2017
.DISCUSSION...Have made some minor changes to the POPs for tonight
and have scaled back on the coverage as showers appear to be
rapidly dwindling. Meanwhile, kept at least some mention of
showers and storms tonight as the stalled frontal boundary
meanders across the Rio Grande Plains and for possible convective
activity over the Mexican Plateau that could drift east into
western portions tonight. The best chances will be possible over
the coastal waters as they are more convectively unstable
overnight.
&&
.PREV DISCUSSION... /issued 659 PM CDT Mon May 22 2017/
DISCUSSION...Updated for latest aviation discussion below.
AVIATION...A stalled front and a variety of convective outflow
boundaries are currently in place across the Mid to Lower RGV with
some shower activity near KMFE. This activity should pass through
quickly with an otherwise mostly rain-free evening expected.
Models do indicate some isolated showers overnight as weak
impulses moves through the mean flow and interact with the nearly
stationary front. However, confidence on placement or timing
remains too low to mention in the TAFS. Meanwhile, low MVFR clouds
will likely form again overnight as predominately SE winds allows
moisture to increase. For Tuesday, there is some indication for
showers or storms as the stalled front meanders across the area
during the morning and afternoon time frame. However, by the late
afternoon or early evening, a cold front will move south through
the region with more widespread showers and thunderstorms
expected...with some storms possibly becoming severe.
PREV DISCUSSION... /issued 229 PM CDT Mon May 22 2017/
SHORT TERM (Tonight through Tuesday Night): A stalled front resides
over the CWA, with a radar signature pushing slowly across Willacy,
Hidalgo, and Cameron Counties. But despite continued rich low level
moisture and available buoyancy, ongoing isolated to scattered
convection should weaken tonight. The HRRR prolongs convection out
west over the Sierra Madre range into tonight, so can`t rule out a
few storms moving into the Zapata and Starr sector. Overnight low
temperatures will be propped up in the 70s by high dew points, with
low clouds moving in on light southeast marine winds.
Winds will be light to moderate Tuesday, and possibly northeast on
the backside of washing out frontal boundary. Another front will
push south from the southern Plains during the day, edging through
Tuesday afternoon and Tuesday night, with convection increasing in
coverage as the front overtakes the residual stationary front and
interacts with a ready supply of rich low level moisture, supported
to some extent by destabilizing energy aloft. The GFS shows a vort
max moving off the Mexican mountains in the evening which could help
prolong convection and support stronger cells moving toward the
coast. The forecast sounding for Cameron County Tuesday afternoon
boasts a PW of 1.90 inches, historically above the 90th percentile
for the day. The lapse rate will be a healthy 8 deg C per km. CAPE
will be 3700 J/kg with a supercell parameter of 9.0, and a SHiP of
1.9, supportive of supercells and significant hail. The probability
of severe convection Tuesday to Tuesday night in conjunction with
this event is currently rated at slight, or 15%, by SPC, focusing on
the threat of large hail and damaging wind/wind gusts. Brief heavy
downpours will be possible in any stronger storms.
The arrival of cooler, drier air along with the lingering rainfall
potential should put the kibosh on convection later Tuesday night,
and also allow low temps to dip into the 60s for the northwest 2/3
of the CWA.
LONG TERM (Wednesday through Monday): Surface high pressure will
continue to bring drier air into the Rio Grande valley and
northern ranchlands Wednesday as northwest flow aloft provides
subsidence across the state as the 500mb trough across the
central United States moves eastward. 500mb ridge across the
southern and central Plains Thursday will continue to provide
subsidence across south Texas even as an onshore flow returns at
the surface. A somewhat zonal flow develops across the southern
tier of the country Friday before an upper level trough develops
across western U.S. Saturday and moves eastward across west TX
Sunday. This will allow moisture to increase across portions of
north-central TX through the weekend and convection is progged to
develop across north TX late Sunday and move southward Monday as a
weak cold front moves southward across the state. This will
provide a chance of showers and thunderstorms for the upper
portions of the Rio Grande valley late Monday.
MARINE (Now through Tuesday night): Light to moderate southeast
to south winds tonight and Tuesday, shifting to moderate north
late Tuesday night in the wake of a cold front. Low to moderate
seas. Scattered showers and thunderstorms, some strong to severe
late Tuesday.
Wednesday through Saturday...Moderate north to northeast winds
will prevail across the coastal waters Wednesday before high
pressure across the lower Texas coast moves eastward Wed night.
Winds will veer to the southeast Wed night and increase Thursday
as the pressure gradient increases across the western Gulf of
Mexico with low pressure across the TX panhandle and high pressure
across the northern Gulf. Moderate to strong southeast winds will
prevail across the lower TX coast Thursday through Saturday. SCEC
to borderline SCA conditions will prevail across portions of the
coastal waters Thursday through Saturday.
&&
.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&
$$
This product is also available on the web at:
HTTP://WEATHER.GOV/RGV
69/58
Area Forecast Discussion
National Weather Service Green Bay WI
1020 PM CDT Mon May 22 2017
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Tuesday
Issued at 226 PM CDT Mon May 22 2017
The latest rap analysis and satellite/radar imagery show upper level
low pressure centered across Lake Superior, a compact shortwave
moving east over South Dakota, and a surface trough positioned over
southern MN into Nebraska. Scattered showers will continue to move
east from northwest WI into north-central and far NE WI for the rest
of the afternoon. Instability has been slow to build over central
and east-central WI so far today, but continue to see cu build up in
this area, and hi-res mesomodels continue to point towards some
showers developing. Any thunderstorms will most likely be isolated
given the lack of forcing and instability. More widespread shower
activity exists over SD with the compact vort max. As this
shortwave moves towards the area late tonight into Tuesday, rain
chances and trends will be the main forecast concerns.
Tonight...Upper troughing will continue to reside across the
northern Great Lakes, while the shortwave trough over eastern South
Dakota moves into southwest Wisconsin late in the night. A few
showers over far northern WI and also over east-central WI could
linger into the mid-evening hours. Once the lingering showers
diminish, should see a lull in the precip chances until the
shortwave over SD and associated surface low move into southwest
Wisconsin late. Did slow the chances down somewhat based on the
latest model data. Low temps ranging from the upper 30s in the
north to near 50 over the southern Fox Valley.
Tuesday...The shortwave will swing northward across western
Wisconsin, and will lay out a convergence zone just west of the Fox
Valley and Bay of Green Bay. Though some showers will likely be
moving northeast across central WI at the start of the morning, this
convergent zone looks to be the focus for shower activity for the
rest of the day. Do not see much instability with clouds and precip
arriving in the morning, so left the mention of thunder out of the
forecast. Temps will be cooler in many spots, and range from the
upper 50s to low 60s across the region.
.LONG TERM...Tuesday Night Through Monday
Issued at 226 PM CDT Mon May 22 2017
Precipitation trends are the main forecast concern.
An upper level trof and inverted surface trof will bring
showers to the entire region Tuesday night, and to the
southeast portion of the forecast area on Wednesday.
A weak ridge of high pressure will bring dry conditions
Wednesday night into Thursday evening, but small rain
chances will return as WAA develops late Thursday night
into Friday.
A series of weak short-wave trofs and associated cold fronts
will continue to bring periodic bouts of scattered showers
thunderstorms through the Memorial Day weekend, but the majority
of the period should be dry. Have sided more with ECMWF, as the
GFS has been exhibiting signs of convective feedback issues with
the weekend forecast over the last few days.
Below normal temperatures at the beginning of the period will
moderate to slightly above normal by Friday and Saturday, then
back to normal for the end of the holiday weekend.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1020 PM CDT Mon May 22 2017
Isolated convection noted along a boundary extending
over east central Wisconsin late this evening. This boundary
extends to a low pressure system and upper disturbance over
northeast iowa. Anticipate more isolated showers and storms along
this boundary overnight with mainly vfr conditions. Shower
activity may become more numerous over central and east central
Wisconsin Tuesday along with MVFR/IFR cigs developing. Since the
showers may be more scattered to isolated across northern
Wisconsin, mainly MVFR cigs anticipated through Tuesday afternoon.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......Kieckbusch
AVIATION.......TDH
Area Forecast Discussion
National Weather Service Jackson MS
1002 PM CDT Mon May 22 2017
.UPDATE...
Updated for evening discussion.
&&
.DISCUSSION...
As of 230z, a surface low was located near the MS/LA line just NE
of Baton Rouge with an inverted trough axis extending into central
MS and a baroclinic zone just inland separating a moist unstable
marine layer from cooler more stable air to the north. Meanwhile
aloft, broad troughing is located across the central US with a
coupled jet structure supporting upper level divergence across the
ArkLaMiss. Strong isentropic ascent above the baroclinic zone in
concert with the aforementioned coupled jet helped to support an
expansive area of moderate to heavy stratiform rain across a large
portion of the CWA this afternoon and is still ongoing, but lower
rainfall rates with this area of precip have precluded a greater
flash flooding threat so far. Latest RAP analysis also indicated
the presence of an internal diabatically enhanced potential
vorticity anomaly which has helped to strengthen the low level
flow and moisture advection into the area. For the remainder of
the evening, the heaviest rainfall is starting to edge into the
south central portions of the forecast area and will slowly spread
further north and east overnight. This is where the flash
flooding potential will be maximized mainly south of the I-20
corridor where 2 - 4 inches of additional rainfall with some
locally higher amounts will be possible. As such, the current
flash flood watch and limited/elevated areas in the HWO look well
placed and will let ride as is for now. The majority of the
lightning activity has been well offshore over the Gulf and with
little instability not expecting any severe weather so the
marginal risk was removed in accordance with the latest SPC
outlook. However, an isolated lightning strike or two cannot be
entirely ruled out as a few pockets of moist absolutely unstable
layers move through the area. Last, but not least, a few areas of
patchy fog are possible tonight mainly along the Hwy 84 corridor
and portions of the Delta as the rain moves off to the east. /TW/
Prior discussion below:
Rain has been slow to advance east today, but saturated lower
levels now are ensuring much more reaching the ground. Surface low
over southeast TX remains responsible for the widespread
isentropic ascent and should continue tonight as the low moves
along the baroclinic zone along the coast. Have some concern that
the low may shift a bit to the north as better baroclinicity
actually exits from west central LA into southwest MS. If this
occurs, heavier rainfall could develop further north than expected
right now. As of now, expect around 2 inches in the far south
with locally higher amounts.
Most of the heavy rainfall will depart into AL by 12Z Tuesday, but
digging mid level trough and at least a few breaks in the cloud
cover should be sufficient for scattered thunderstorms in the
afternoon. The best lapse rates will occur in the east during the
afternoon and with around 40 knots of deep layer shear, would not be
surprised to see some isolated severe storms here./26/
Tuesday night through Sunday...our winds aloft will remain out of
the southwest as a closed low drops south from the Upper to Mid-
Mississippi River Valley by Wednesday morning. A shortwave rounding
the base of the closed low will swing east across our CWA and help
support a weak cold front and another good chance of showers and
storms Tuesday night into Wednesday. Cooler and drier air will
filter into the CWA in the wake of the cold front but the closed low
will continue to drop southeast across northeast Mississippi and
maintain light rain chances over the northeast half of our CWA
during the day Wednesday. By Wednesday evening, dry weather is
expected and the skies will clear from the southwest. With mostly
clear skies and a drier airmass over the area, the coolest morning
lows of the forecast period are expected Thursday. Most sites will
bottom out in the lower 50s. Thursday and Friday will be dry with a
warming trend. Low amplitude ridging aloft will move over our CWA
while a surface high strengthens over the northwest Gulf and
ridges back to the west across the Gulf coast states. The
resulting southerly flow will slowly increase moisture back across
our area. Saturday mid level ridging will strengthen over the
Gulf and may limit convection across our southern zones but
elsewhere deep enough moisture will be back across our CWA to
combine with daytime heating to result in isolated to scattered
afternoon and early evening storms. Models differ on timing but
another closed low near the upper Plains and Canadian border will
deepen a trough over the central CONUS Sunday into Monday. This
will lead to increasing rain chances Sunday into Monday. /22/
&&
.AVIATION...
00Z TAF discussion:
A mix of VFR to IFR ceilings are occurring this evening as a large
swath of rain is ongoing over many TAF sites. This will continue
to reduce vis and ceilings through the rest of the evening. Some
heavier showers or storms could occur through the night. Overall,
not good flying conditions through daybreak. Conditions should
improve after 17Z Tuesday. /28/
&&
.PRELIMINARY POINT TEMPS/POPS...
Jackson 64 79 58 73 / 87 48 60 17
Meridian 64 80 60 74 / 91 81 58 32
Vicksburg 61 80 58 75 / 92 37 62 13
Hattiesburg 65 82 63 77 / 89 84 57 22
Natchez 62 79 58 74 / 85 34 62 10
Greenville 60 78 57 73 / 91 34 61 18
Greenwood 62 78 57 71 / 97 42 61 25
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...Flash Flood Watch until 7 AM CDT Tuesday for MSZ052-054>066-
072>074.
LA...Flash Flood Watch until 7 AM CDT Tuesday for LAZ024-026.
AR...None.
&&
$$
TW/22/26/28
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1126 PM EDT Mon May 22 2017
.UPDATE...
Issued at 1110 PM EDT MON MAY 22 2017
Hourly grids were freshened up based on recent observations, which
led to no substantial changes at this time.
UPDATE Issued at 835 PM EDT MON MAY 22 2017
The region remains under the influence of a broad trough that
encompasses much of the Conus east of the Rockies. Within this
trough, a shortwave was moving from the Lower MS Valley and into
the Southeastern Conus. This shortwave is expected to track into
the Southern Appalachians tonight and then northeast of the area
during the day on Tuesday. This system is still expected to bring
a threat of isolated to scattered rain showers late tonight and
on Tuesday mainly across the southeast parts of the area. A
thunderstorm cannot be ruled out on Tuesday as well. As for
tonight and tomorrow, the inherited forecast looks on track with
only slight adjustments to hourly temperatures and dewpoints.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 430 PM EDT MON MAY 22 2017
19z sfc analysis shows high pressure in place over Kentucky,
though it was not effective enough to keep the high clouds at
bay. These, along with light north winds, have helped to keep
temperatures contained in the 60s through the afternoon for most
places. Readings did hit the low 70s in the far south but only
mid to upper 60s, so far, elsewhere. Meanwhile dewpoints are
running in the mid 40s to lower 50s.
The models are in good agreement aloft through the short term
portion of the forecast. They all depict a deep and broad trough
over the mid section of the nation amplifying and dipping
southeast into the mid Mississippi Valley during the next 36 to 48
hours. This will place eastern Kentucky in broad southwest flow
with plenty of energy breaking free to ride over the JKL CWA from
Tuesday afternoon into Wednesday. Toward the end of the period
the GFS solution starts to separate from the ECMWF with the core
of its trough digging a bit closer to Kentucky. Will favor a
general blend through the period with a lean toward the higher
resolution HRRR and NAM12 models through the first part.
Sensible weather will feature a quiet night with some ridge to
valley distinctions opening up after sunset but mitigating late in
the night due to increasing clouds from the south. These clouds
will be the vanguard of a sfc low moving into the southern
Appalachians tomorrow with a few showers possibly sneaking past
the border and into our CWA by dawn. The shower chances will
continue in the far east Tuesday with a few thunderstorms possible
by mid afternoon in these areas. A better chance of showers and
storms then develops to our southwest - pushing in later Tuesday
night - likely washing over the bulk of the CWA by sun-up
Wednesday.
Again used the CONSShort and ShortBlend as the grids` starting
point with some adjustments to lows tonight owing to a ridge to
valley split developing early but mixing out in the east late. As
for PoPs, did tighten them up along our southern and eastern
border late tonight into Tuesday.
.LONG TERM...(Wednesday through Monday)
Issued at 347 PM EDT MON MAY 22 2017
Models are in good agreement with mid and upper level features
through DY5 Friday, then increasingly diverge in solutions from
there. Amplified and somewhat progressive flow will dominate the
pattern through the extended. Upper level low and associated deep
long wave trough will track slowly across the eastern half of the
CONUS through week`s end. Short wave ridging will then transit the
region before a second upper level low or trough drops out of Canada
and into the Midwest and/or Great Lakes region. Most of the
differences showing up after DY5 center around the evolution and
timing of the second main storm system. The 0Z ECMWF is fastest with
this system and the 6Z GFS the slowest. The 0Z Canadian appears to
split the difference. The 12Z Canadian is showing better run to run
continuity than the 12Z GFS and even trends closer to the ECMWF. The
GFS suggests some phasing of the Canadian low with energy moving out
of the Pacific, causing a futher deepening and digging of the system
across the plains and into the Great Lake, a much slower and
stronger solution overall. As a result confidence is quite low for
the last 48 hours of the period.
With respect to sensible weather, unsettled weather with periods of
showers and thunderstorms will tend to keep daily highs near to or
below normal levels for this time of the year and overnight lows
above normal. Good forcing coupled with some instability will
probably bring the threat of some thunder to the area on Wednesday.
In addition, lowering freezing levels may allow for some of the
showers/storms to contain small hail/graupel at times.
A short lived window of dry weather can be expected across eastern
Kentucky Friday, as the aforementioned transient short wave ridge
moves across the Ohio and Tennessee Valleys. The threat of rain
returns to the area Friday night and lingers through the weekend.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 835 PM EDT MON MAY 22 2017
VFR conditions prevail as drier air and high pressure has spread
into the region. However, a low pressure system and mid level
disturbance moving across the Southeastern Conus will brush the
area from the south later tonight into Tuesday. A few showers
could affect the TAF sites late tonight or on Tuesday with perhaps
even a thunderstorm on Tuesday afternoon. However, chances and
confidence were too low to include at this point. LOZ, JKL, and
SJS will stand the highest chances for any of this activity. Even
so, only mid level ceilings are expected with this. Winds will
be relatively light and variable averaging 10kt or less through
the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...JP
SHORT TERM...GREIF
LONG TERM...RAY
AVIATION...JP
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1058 PM CDT Mon May 22 2017
.SHORT TERM...(This evening through Tuesday)
Issued at 335 PM CDT Mon May 22 2017
After a week of rainy weather, the air mass has dried out quite a
bit today with mostly sunny skies over much of southern MN into West
Central Wisconsin. However, two areas of incoming clouds and precip
will affect the area. Mid clouds and some showers had already moved
into southwest MN with associated short wave coming from the
northwest. There might be some thunder in south central MN and have
kept those in the grids. That area will slide across our southern
counties tonight. The other area of clouds and light showers will
drop southward later tonight and Tuesday as upper trough drops
south. This will affect central into southwest MN, and eventually
east central MN into Wisconsin later Tuesday morning and
afternoon. The GFS is rather bullish with more rain and clouds
then most models, but have kept the grids a little quieter than
that.
.LONG TERM...(Tuesday night through Monday)
Issued at 335 PM CDT Mon May 22 2017
A much drier pattern will take hold from the middle of the week
onward, with only two main chances of precipitation - one with a
front Thursday night into Friday and the other Sunday into Monday.
Cyclonic flow will finally be on the way out Tuesday evening.
Clearing skies will follow for midweek although temperatures
remain cool in the wake of the impressively deep trough heading
toward the East Coast. Temperatures rebound back toward normal
Thursday in advance of the front and Friday/Saturday in the wake
of the front where temperatures aloft actually warm a bit. Poor
lapse rates should limit the thunder threat Thursday night/Friday
and the GFS appears to be a bit too aggressive with precip
coverage. Continued with 30-40 PoPs.
Confidence diminishes Memorial Day weekend with GFS maintaining a
closed low over the central U.S. while the GEM/ECMWF are much
farther northeast with the system over the Great Lakes and a
ridge building eastward into the High Plains. Either way,
temperatures will trend back below normal and odds of a weekend
washout appear low.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1058 PM CDT Mon May 22 2017
At 11pm, we are finally starting to see spotty MVFR cigs in
northern MN, though the LAMP and HRRR were both saying this should
be a widespread IFR/MVFR field. As mentioned in 00z discussion,
there was concern the LAMP was overdoing its cig forecast and
certainly trends this evening support that, with forecast
conditions slowly improving in the LAMP. Based on SREF probs, MVFR
cigs are most likely west of MSP, so continued to only have
prevailing MVFR cigs at AXN/STC/RWF. In addition have trends for
these airports more optimistic than what LAMP has. For precip, it
looks to be of the hit- and- miss, on- and- off through the day
Tuesday. Given that expectation, have prolonged periods of VCSH at
all terminals.
KMSP...Confidence is increasing in main MVFR cloud mass remaining
west of MSP this period. Based on HRRR and other CAMs, expect
diurnally driven scattered showers to develop late Tuesday
morning and persist through the rest of the daylight hours.
/OUTLOOK FOR KMSP/
Wed...VFR. Wind NE 5-10 kts.
Thu...VFR. Wind SE 5-10 kts.
Fri...VFR. Chc MVFR/-SHRA. Wind SW 5-10 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&
$$
SHORT TERM...TDK
LONG TERM...BORGHOFF
AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
633 PM EDT Mon May 22 2017
.SHORT TERM...(This evening through Tuesday)
Issued at 409 PM EDT MON MAY 22 2017
WV imagery and RAP analysis indicated a mid/upper level low over
portions of nrn Ontario into the nrn Great Lakes with several weak
shrtwvs rotating around this feature. At the surface, an elongated
low and occluded front was located btwn Lake Superior and James bay.
Vis loop, radar and obs showed abundant low clouds lingering across
Upper Michigan along with some isolated showers or sprinkles through
the cntrl and ern cwa. The -shra were had intensified slightly with
the limited daytime heating.
Tonight, any lingering instability showers should end early this
evening with loss of diurnal heating. As the mid level low pivots
and the stronger qvector conv shifts to the sw of the region,
weak ridging will prevail over Upper Michigan with no pcpn. Expect
enough lingering clouds to keep min temps from the upper 30s to
the lower 40s.
Tuesday, the stronger 700-300 mb qvector conv with the shrtwv
digging into IA will continue to remain to the south of Upper
Michigan. There may still be enough forcing and moisture ahead of
the mid level trough axis along with some weak instability from
daytime heating to support sct -shra over the srn cwa. Otherwise,
temps will remain below normal with highs from the lower 50s near
Lake Superior to thearound 60 south.
.LONG TERM...(Tuesday night through Monday)
Issued at 307 PM EDT MON MAY 22 2017
The main forecast highlights through the middle to end of the week
will be a drying and warming trend, a few locations across the
interior may see temperatures climb into the lower 70s by Friday!
Rain chances look to return on Friday across the west, and pushing
eastward into Saturday as a cold front pushes east across the area.
There is some uncertainty as to whether or not instability will
return this far north, so confidence in any thunderstorm activity is
low right now. Towards the end of the weekend and beginning of next
week, another system is progged to impact the region, bringing back
better chances for precipitation. Patchy frost looks possible across
the interior west early Thursday morning as a drier air mass moves
in and skies clear giving way to ample diurnal cooling.
Tuesday night, with lingering upper-level energy overhead, as the
main trough axis slowly continues to push east across the area,
expect light rains to linger across the central and eastern portions
of the area. Wednesday, expect clouds to linger across the area
before diminishing through the afternoon as high pressure begins to
build southwest across much of the area. However, the exiting upper-
level low is progged to linger just north of the Ohio River Valley
and may overspread mid and upper-level clouds across the eastern
half of the area. Wednesday night into Thursday, as the upper-level
low begins to lift slightly, a few medium range models bring back
precipitation chances across the far east as weak warm air advection
tries to nudge back to the northwest. The Canadian is by far the
most aggressive with this precipitation, which is likely in response
to lingering shortwave activity being a bit more robust. During the
day on Thursday, the upper-level low will continue to slowly lift
east, but a few lingering wrap around showers may impacted far
eastern portions of the area; therefore, have held onto the slight
chance wording for rain showers through the day. However, across the
rest of the area as weak upper-level ridging builds into the region,
expect skies to be mostly sunny with ample insolation. This will
allow for temperatures to modify back to near normal for this time
of year.
Friday through Friday night a weak cold front is progged to move
east across the area, bringing back chances for rain showers. The
upper-air pattern is rather complex during this time period, with
longwave troughing extending south across the Northern Plains and
transitioning to more zonal flow across the central and southern
Plains. Given this split flow, confidence is not high that enough
moisture will get this far north to support instability for
thunderstorms. This is further supported by medium range models
continuing to trend further south with the northern extent of
MUCAPE.
Depending on the speed of the front, precipitation may linger into
Saturday. The Canadian is the slowest, with the front moving across
Upper Michigan almost 12-18 hours after the GFS/ECMWF. Saturday may
be a bit cooler in some locations depending on the speed of the cold
front. Sunday into Monday, there is considerable uncertainty in how
things will evolve. The longwave trough across the western CONUS is
much stronger in the GFS and weaker within the Canadian, with the
ECMWF falling in the middle; therefore, model solutions are a bit
all over the place precipitation wise. However, given the lingering
upper-level energy rotating about the region and the possibility for
another shortwave digging south out of central Canada, expect
temperatures to be on a slight downward trend through early next
week with cloudy skies.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 633 PM EDT MON MAY 22 2017
MVFR conditions will develop again with cooling overnight and
additional moisture advection. Winds will also be light enough to
allow fog formation that may drop vsby to IFR for a short period
Tuesday morning. SAW will go up to VFR with mixing during the day on
Tue.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 409 PM EDT MON MAY 22 2017
A low pres trough lingering over the area will maintain fairly light
winds across the lake through Tuesday. Winds under 20 kts should
then be the rule into Fri as a relatively flat pres gradient
dominates the Upper Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Ritzman
AVIATION...07
MARINE...JLB
Area Forecast Discussion
National Weather Service Norman OK
738 PM CDT Mon May 22 2017
...UPDATE...
&&
.DISCUSSION...
Made minor adjustment to precipitation probabilities, adjusting
upward for much of central Oklahoma based on trends. 00z KOUN
sounding revealed little instability and so ongoing strong/severe
convection across southwest Oklahoma should weaken before
impacting the I-35 corridor later this evening. Latest RAP
sounding has 1,000-1,500 J/kg of MLCAPE across southwest Oklahoma
and this is supporting a few intense cells with hail being the
main concern. One anti-cyclonic mesocyclone that persisted across
eastern Beckham County eastward toward Clinton produced golf ball
size hail on the south side of Elk City. Per Bunkers shear
vectors, left movers will most east-northeast at around 25 knots
and right movers will move southeast at aruond 30 knots. Storm
intensity and the severe threat should wane as storm intensity
decreases later this evening.
Otherwise only minor adjustments were made to other fields
including wind.
BRB
&&
.PREV DISCUSSION... /issued 730 PM CDT Mon May 22 2017/
DISCUSSION...
AVIATION... /For the 00z TAFs/
Latest regional radar mosaic shows showers moving across much of
central and northern Oklahoma impacting PNC/OKC/OUN, but moving
away from GAG/WWR. In the short term, the TAF sites with greatest
concern are CSM and HBR. Thunderstorms may impact these sites
through 02-03z and could even approach LAW. Once showers move east
of the area by late evening, VFR conditions are expected. We`ll
need to monitor ceilings later tonight through tomorrow morning as
some locations could briefly see MVFR conditions but confidence
was too low for inclusion at this time.
BRB
PREV DISCUSSION... /issued 314 PM CDT Mon May 22 2017/
DISCUSSION...
The main concerns are rain/storm chances/potential tonight
into Tuesday.
Ongoing isolated to numerous light showers across central and
northern Oklahoma as of 3 pm should weaken in the next several
hours as isentropic lift around 700 mb weakens. This activity
will remain rather light. Some thunder may occur with this
activity, but do not think any strong or severe storms will
occur due to limited instability (MUCAPE mainly below 600 J/kg).
Severe thunderstorm potential now through tonight still appears
to be low with decreasing confidence. Cloud cover and rain have
limited instability in most locations north of a Mangum to
Seminole line. South of this line, some sun and daytime heating
have allow temperatures to rise into 70s. A few thunderstorms may
form near and this cloud shield line in the next several hours,
though this remains doubtful due to sufficient capping. Higher
chances for severe storms appear to occur over far eastern New
Mexico into west Texas late this afternoon where the air is more
unstable. This activity will continue to move east and southeast,
which may glance western north Texas and far southwestern Oklahoma
this evening if they can organize into a complex or two. If
severe storms occur, some severe hail and wind reports, mainly on
the lower end of severe spectrum (hail less than golf ball size
and winds under 70 mph), would be possible. No severe storms are
expected north of the line mentioned above due to limited
instability.
After midnight tonight into Tuesday morning, a cold front will
move south and through the area. A few lingering weak showers and
thunderstorms may occur across the area.
Tuesday afternoon, some clearing can be expected, though
temperatures will remain on the cool side for late May. Sufficient
daytime heating may allow for isolated to scattered showers and
weak thunderstorms to form in rather chilly unstable airmass. If
storms occur, no severe storms would be expected due to limited
instability (less than 500 J/kg), however small hail up to nickels
and gusty winds up to 50 mph could result.
Tuesday night through Thursday, dry weather is expected. Thursday
will be warmer (possibly much warmer) than Wednesday.
Friday through Memorial Day, a warm/hot humid airmass may evolve
across the southern Plains Friday through early Sunday, along for
some potential for severe thunderstorms/heavy rainfall. Most
models have been consistently depicting rather high amounts of
potential instability (MUCAPE 2000-5000 J/kg), high low level
moisture (surface dewpoints in the 60s to lower 70s), and
sufficient shear (0-6 km bulk shear 30-50 kt) for severe storms
with heavy rain late Friday through early Sunday. Capping may be
strong and limit storm development. For now, kept low chances for
storms across the area Friday night into Sunday. Have low
confidence in severe storm and heavy rainfall potential during
this time frame. Slightly cooler and drier conditions may occur
with the passage of a weak cold front Sunday into Memorial Day.
MBS
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 71 55 70 48 / 60 60 20 10
Hobart OK 70 53 70 47 / 80 60 20 0
Wichita Falls TX 73 59 72 51 / 30 50 40 0
Gage OK 66 50 68 43 / 60 30 20 10
Ponca City OK 73 53 69 47 / 40 60 20 10
Durant OK 75 58 70 51 / 20 40 40 10
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
12/14
Area Forecast Discussion
National Weather Service Blacksburg VA
1149 PM EDT Mon May 22 2017
.SYNOPSIS...
A cold front from Pennsylvania to northern Georgia will move
southeast and stall across North Carolina by Tuesday as high
pressure wedges down the Appalachians. Yet another area of low
pressure will arrive midweek with added rainfall likely for
Wednesday and Thursday. Friday will be the drier day this week.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 1132 PM EDT Monday...
Watching slow moving moderate to heavy showers in the NC
foothills/piedmont, along a weak convergence zone leftover by
the front. Models indicate that isolated to scattered coverage
will be the way to go over the next few hours per moisture
convergence off the high-res models. Appears best rainfall will
say just south of our CWA but looking for some increase
northward overnight as low level flow turns to the southeast.
The latest RAP indicates better deep moisture convergence
pooling toward the NC foothills after 06z, but only briefly.
Looks like rain showers will spread northeast along the Blue
Ridge through morning, while other are surges northeast to the
southside of VA. At the moment QPF seems low enough to not have
any watches at this time. Better threat arrives more toward
dawn. Will be watching slow moving cells for any local
advisories.
Previous discussion from early evening...
Enough of an instability gradient over the NC foothills/piedmont
to keep isolated to scattered convection around this evening.
The high-res (HRRR/RAP) favor showers/a few thunderstorms from
the NC/VA border in the foothills through southside VA through
this evening, then should be weakening somewhat, transitioning
to a more rain.
Previous discussion from this afternoon...
Water vapor loop showed a well defined short wave over Arkansas
early this afternoon. Models track this feature into southern
Virginia overnight.
Surface and 850MB front cross the area this afternoon, but with
little change in air mass behind it. 850MB winds back to the
southeast by midnight brining the deep moisture north along the Blue
Ridge and foothills. Best convergence will be from 12-18Z/8AM-2PM
Tuesday. GFS may have some convective feedback and may be moving the
wave too fast and too far northeast compared to other guidance. Some
decent isentropic lift on the 3km NAM Tuesday morning. Leaned toward
NAM and WPC for QPF .WIll have to monitor amounts since some
locations have had lots of rain in the past 72 hours and have
saturated soils as a result.
Surface front reaches central North Carolina as high pressure moves
from West Virginia into Pennsylvania. By Tuesday morning the in-situ
wedge will be in place down the Appalachians aided by precipitation
on the cool side of the front. Clouds and precipitation will keep
temperatures down on Tuesday. Trending toward cooler guidance for
maximum temperatures.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 330 PM EDT Monday...
Large upper trof will be traversing the eastern US, keeping us in a wet
pattern through the period.
Multiple waves along the front to our east will be pulling away from
the region Tuesday night. However, a low over the Ohio valley will be
captured by the upper trof as it closes off and the stacked system will
wrap up a cold front a push it into our area from the west Wednesday
morning. There will be a bit of an in-situ wedge ahead of the front to
limit instability and convective development, but good isentropic lift
and dynamic support will make for widespread rainfall and some possibly
some embedded thunder from lift over the stable layer. Also, there may
be a very narrow window just ahead of the front where the wedge has
weakened that may allow for deeper instability to support elevated
convection in a highly sheared environment. While the overall
probability of severe weather is low, the situation bears watching
until fropa occurs early Wednesday night. Expect some lessening of
showers overnight Wednesday night in muddy dry slot of stacked low
spinning over the Ohio valley.
Diurnal heating will pop showers and thunderstorms with steepening
mid/upper lapse rates under the cold pool aloft as the upper trof
swings through. Small hail/graupel in low topped convection look
possible mainly west of the Blue Ridge. Showers/storms taper quickly
with loss of heating in the evening, leaving some lingering upslope
precipitation west of the Ridge into Friday morning.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 330 PM EDT Monday...
Our unsettled pattern will continue through the weekend as a
progressive upper ridge moves across the eastern US, followed by the
development of another closed low moving through the upper midwest.
This will allow a frontal boundary to sink into the region from the
north and stall on Saturday, with a series of waves shearing off to our
north dragging along weak, occluded fronts. While not likely a complete
washout, we look to keep a good chance of showers and thunderstorms in
the forecast through the weekend and into the first part of next week.
&&
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
As of 725 PM EDT Monday...
Expect VFR this evening, the rain should start spreading
northward overnight and cigs will start to sink to MVFR or
lower, especially along/east of the Blue Ridge. The rain will
become steadier and possibly heavier late tonight into Tuesday
from BCB/ROA east.
This pattern will stick around through the end of the taf
period, but rain will be lighter over BLF/LWB.
Extended Aviation Discussion...
The chance of precipitation continues Wednesday and Thursday
with sub-VFR conditions associated with any of the
precipitation. Friday will be drier with a better chance of VFR
ceilings and visibilities. Another front reaches the area for
Saturday with more precipitation and sub-VFR conditions.
&&
.HYDROLOGY...
As of 345 PM EDT Monday...
An inch to inch and a half of rain is expected tonight and
Tuesday. Amounts will have to be monitored as some locations
along the Virginia/North Carolina border, especially Carrol,
Patrick and Henry Counties in Virginia and Stokes, Rockingham,
and Caswell Counties in North Carolina. FFG along parts of the
southern Blue Ridge was in the 1.5 to 2.5 inch range.
More rainfall is expected Wednesday and Thursday, which could
lead to small stream and river flooding. Models continue to
favor areas along/east of the Blue Ridge, possibly resulting in
another 1 to 3 inches of rain.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/WP
SHORT TERM...MBS
LONG TERM...MBS
AVIATION...AMS/JH/WP
HYDROLOGY...AMS
Area Forecast Discussion
National Weather Service Shreveport LA
1015 PM CDT Mon May 22 2017
.DISCUSSION...
Much of the -SHRA has shifted E of the region this evening with
the departure of our shortwave trough...but mosaic radar imagery
still depicts a weak low level circulation over SW LA N of LCH
associated with a weak sfc low along a stalled frontal bndry
extending from just offshore Sabine Pass NE to near LFT, into Srn
MS N of MCB. This has resulted in some wrap-around -RA/-DZ over
the Srn and Ern sections of Ncntrl LA, which should gradually
shift E overnight as this sfc low lifts ENE across SE LA. Also
seeing patchy -RA/-DZ farther W still lingering over portions of
Deep E TX S of I-20 based on the low 02-03Z cigs/reduced vsbys,
which also look to longer overnight as well. Farther NW...areas of
sct slightly elevated convection continues to build SE towards the
Red River of Srn OK/N TX, associated with a subtle shortwave that
will eject ESE into SE OK/NE TX and into SW AR late. The short
term progs suggest that this shortwave may dampen with time
overnight as it approaches the region, and should also encounter
slightly drier air especially as it enters SW AR. This convection
should weaken in intensity as it approaches the region given the
stability noted on the 00Z KSHV raob, but the advection of
slightly steeper 700-500mb lapse rates warrants the continued
mention of isolated thunder over NE TX/SE OK/SW AR/NW LA.
Have updated the forecast to lower pops down to low chance across
the SE sections of Ncntrl LA with the departure of the shortwave,
and have also removed thunder mention as well. Did maintain low to
mid chance pops late over NE TX/SE OK/SW AR/NW LA, with the progs
not very bullish with the convection able to progress across these
areas through daybreak. However, the latest run of the HRRR
has changed significantly as of this time, and suggests the
convection affecting more of these areas as well as all of SW AR.
The HRRR also depicts additional convection over Wcntrl TX also
pushing E and possibly affecting the SW sections of E TX prior to
daybreak as well. A brief lull in the rain is expected Tuesday
morning, but we will await the arrive of the upper trough now
digging SSE into the lower TX Panhandle to trigger sct to numerous
areas of convection over the region by afternoon.
Did make a few minor (cooler) adjustments to forecast mins tonight
as well, but otherwise, the current forecast still looks good.
Zone update already out...grids will be available shortly.
15
&&
.PREV DISCUSSION... /issued 737 PM CDT Mon May 22 2017/
AVIATION...
For the ArkLaTex, the last of the ra is edging East, but some
DZ/BR/FG will all become likely with the setting of the sun.
Overnight winds will be light and the ground saturation will wick
into the air and keep all night. Slow improvement to occur with
another fropa by this time tomorrow evening. Look for FG/BR/cigs
to slowly lift by lunch and then shwrs/tstms to become likely as
the cold front moves over the area. Climb winds are light and
flight levels have a good W/SW jet 50-100KT from FL220-FL350. /24/
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 58 75 54 76 / 20 50 40 10
MLU 60 78 57 76 / 30 30 60 10
DEQ 56 73 49 74 / 30 60 20 10
TXK 56 73 52 75 / 20 50 30 10
ELD 56 74 52 74 / 20 50 40 10
TYR 59 73 54 78 / 20 60 20 10
GGG 58 74 54 77 / 20 60 30 10
LFK 62 79 58 81 / 20 60 40 0
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
15
Area Forecast Discussion
National Weather Service Tallahassee FL
920 PM EDT Mon May 22 2017
.NEAR TERM [Through Tonight]...
The 7 pm surface analysis showed a quasi-stationary front from VA,
through central AL, through coastal LA, and into south TX. The
airmass ahead of this front was warm and very moist with PWAT
values about 40% above climo for our region. All of the large
scale models forecast weak Q-G forcing to persist overnight across
our forecast area. This, combined with favorable thermodynamics,
justifies keeping at least 20% PoPs. However, early Tuesday
morning the HRRR generates a more widespread area of rain across
the FL Panhandle and southeast AL as a perturbation associated
with an MCS (currently over LA) reaches our region. This solution
is supported, at least in part, by other CAMs. At this time we do
not expect this rain to be particularly heavy.
&&
.PREV DISCUSSION [743 PM EDT]...
.SHORT TERM [Tuesday Through Wednesday Night]...
A closed upper low north of the Great Lakes will open up as it
lifts off to the northeast. Meanwhile, a shortwave over MN will
drop southward with a low closing off over Iowa on Tuesday. This
feature will continue southward into the Missouri Valley on
Wednesday digging a deep trough along and east of the Rockies
before beginning to move toward the east coast Wednesday night. A
few upper level impulse accompanied by deep layer moisture along
with a surface front stalling near the Gulf coast will bring a
very wet pattern to our area through Wednesday. The first
shortwave will arrive tonight and linger through Tuesday bringing
with it widespread showers and thunderstorms. Along with the
potential for heavy rainfall, SPC has our entire CWA highlighted
for a marginal risk of severe thunderstorms. ECAM guidance shows
the potential for MLCAPE as high as 1500-1800 J/KG Tuesday and
forecast soundings show bulk shear values and an 85H jet of 30-40
kts. Additionally, PW`s will increase to around 2.0". The
greatest severe threat will be damaging straight line winds but a
tornado cannot be ruled out.
There should be a short break in convection late Tuesday/early
Wednesday before the next and more significant shortwave arrives
ahead of the main upper trough. Expect another round of widespread
showers/thunderstorms Wednesday with rain chances tapering off
from west to east Wednesday night as the cold front pushes
through the region. SPC has all but a portion of the SE Big Bend
highlighted for a marginal risk with the SE Big Bend in the
slight risk. Bulk shear and the low level jet are forecast to be
in the 40-50 kt range but the limiting factor may be the lack of
instability due to the earlier convective complex.
As for the heavy rain threat, we will hold off on issuing a flash
flood watch as latest QPF amounts have come down just a bit with
the higher amounts (at or just above 3") shifted to our
easternmost zones. These amounts are spread out through Wednesday
night.
.LONG TERM [Thursday Through Monday]...
Much drier air will begin to arrive on Thursday in the wake of the
cold front and remain in place through Saturday. Temperature and
humidity levels will be below normal for late May through Thursday
night with a gradual increase to seasonal levels by the weekend.
Rain chances will return Sunday into the first part of next week
with the approach of the next cold front.
.AVIATION [Through 00Z Wednesday]...
A few showers and isolated thunderstorms near TLH will gradually
dissipate this evening and VFR conditions are expected across our
area tonight under broken mid-high level clouds. Chances for
showers and thunderstorms will increase across our area from west
to east Tuesday morning, with periods of MVFR cigs and visibility
likely at all terminals through the remainder of the day. Brief
IFR/LIFR conditions cannot be ruled out in stronger thunderstorms,
but VFR conditions are also possible during dry periods between
showers/storms.
.MARINE...
Modest southwest winds will increase quickly on Tuesday to
cautionary levels. A period of advisory levels winds and seas is
expected late Tuesday through Wednesday night with the approach
and passage of a strong cold front. Winds and seas will gradually
diminish through the remainder of the work week as high pressure
builds over the waters.
.FIRE WEATHER...
No concerns.
.HYDROLOGY...
Recent rains over the last 48 hours have deposited the heaviest
amounts (3-4 inches) in the upper Choctawhatchee River Basin in
Southeast Alabama. Elsewhere, rainfall amounts have been lighter
generally 2 inches or less. Most of the guidance suggests that
rainfall over the next 36 to 48 hours should generally be in the
3-4 inch range with isolated heavier totals up to 6 inches. While
this could cause some minor flooding issues, slightly higher
amounts would be needed to cause a greater flood threat. Thus,
will not be issuing a flash flood watch on this cycle, though as
confidence increases in the placement of Tuesday`s convection a
watch may be needed.
The threat for river flooding from this system remains quite low,
given that many rivers were at significantly low levels from the
ongoing drought. Only the Choctawhatchee River, which has received
modest rains in the upper portion of the basin is vulnerable to
minor flooding should heavier amounts on Tuesday materialize.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 69 81 68 80 60 / 30 70 70 70 20
Panama City 74 81 71 80 65 / 60 70 70 70 10
Dothan 69 78 67 80 59 / 70 90 70 70 10
Albany 71 78 67 79 60 / 50 80 70 70 10
Valdosta 70 81 67 79 61 / 30 70 70 80 30
Cross City 71 83 71 81 65 / 20 60 70 80 50
Apalachicola 74 80 72 82 65 / 30 60 70 70 10
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Fournier
SHORT TERM...Barry
LONG TERM...Barry
AVIATION...Lahr
MARINE...Barry
FIRE WEATHER...Fournier
HYDROLOGY...Godsey