Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/28/19
Area Forecast Discussion
National Weather Service Caribou ME
1201 AM EDT Tue May 28 2019
High pressure will build in from the west overnight and crest
over the area Tuesday. Low pressure will track south of the Gulf
of Maine Tuesday night followed by high pressure on Wednesday.
.NEAR TERM /THROUGH TUESDAY/...
Update 12:00 AM: Adjustments made based on latest observations.
No other changes.
A cold night coming up. The cold front is making its way off
the coast attm w/winds from the NW. Drier air behind the front
as dewpoints have dropped off in the mid/upper 20s across the n
and w. This drier air will make its way all the way to the coast
by the evening. The latest radar loop showed some light returns
across the central areas moving se. Most of the activity was
shrinking as it headed se. The latest HRRR and Hi Res WRF did a
good job in depicting these light showers. Decided to use a
blend of these high res guidance showing the showers dissipating
as they head to the coast this afternoon. Satl imagery showed
distinct clearing line making steady progress across much of
northern Maine. This clearing line is shown the the HRRR/NAM12
and GEM to be off the coast by the evening. Winds will start to
drop off later in the evening and w/clearing skies, temps will
drop off sharply. The cold air and dry airmass will lead to some
cold temps overnight leading to frost development. Thought
about expanding the Frost headlines into the central areas,
including the Lincoln and Dover-Foxcroft area, but after further
assessment, decided to keep the Frost headlines as is for now.
Some low lying sites in the central zns could see some patchy
frost and did include this wording, but not expecting anything
widespread. Decided on the CONSRAW and GEM temps for the
overnight lows showing colder readings in the valleys.
For Tuesday, sunshine to start out the day and after a cold
start, daytime temperatures should respond accordingly reaching
the 60s across the CWA. This is still below normal for late May.
Expecting clouds to move in from sw to ne in the afternoon
w/line rain moving into portions of the Maine Central Highlands
down to the coast. The GEM and NAM show the northern edge of the
rain making into Dover-Foxcroft and Calais by early evening. The
12z GFS is close by w/its solution. Decided to bring a chance
for some light rain into the aforementioned areas by 7 PM. The
guidance shows the best forcing across swrn Piscataquis County and
the Bangor region. High pres anchored to the ne will keep the
northern areas dry.
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
A small low tracking into southern New England Tuesday night will
spread rain into the southern half of our region while the north
remains partly cloudy. The fast moving low will continue south of
the Gulf of Maine early Wednesday morning. Rain should taper off
before dawn with Downeast remaining mostly cloudy early Wednesday
morning and the north partly cloudy. Weak high pressure will build
over the area on Wednesday. This will bring a partly sunny midday
and afternoon. A weak cold front will approach the north Wednesday
night as a weather disturbance tracks well south of the area. Some
showers may begin to stray into far northern areas by early Thursday
morning. Otherwise, Wednesday night into early Thursday morning will
be partly to mostly cloudy across the area with an increasing
southerly breeze ahead of the cold front. The front will stall just
to our north on Thursday with the north and Downeast mostly cloudy,
and central areas partly sunny. The southerly breeze will continue
on Thursday drawing increasingly humid air north into the
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
The cold front will begin to press into the area Thursday night
drawing moisture north from the small low tracking into southern New
England. This will bring showers across the area, and possibly some
isolated elevated thunderstorms. The showers will taper off early
Friday morning. Downeast will become mostly sunny Friday while cool
air aloft keeps the north partly to mostly cloudy under
stratocumulus clouds. Clouds will increase Friday night into
Saturday as moisture in a return southwesterly flow lifts into the
area. A few showers and possibly an isolated thunderstorm will be
around Saturday as cool air aloft moves in on an approaching
shortwave. A secondary cold front will bring showers and possibly a
thunderstorm Saturday night followed by cooler conditions and
scattered showers Sunday as an upper level trough drops down over
the area. The cool and unsettled conditions will likely continue
into Monday with spotty showers lingering as the upper trough
remains across the area. Overall, the blocking pattern of "negative
NAO", featuring warmer than normal weather over far northeastern
North America and an upper level trough across eastern Canada and
the far northeastern US looks like it will persist at least through
early next week keeping our weather generally cool and
.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
NEAR TERM: VFR into Tuesday for all terminals. Mid and high
clouds apch during the day w/cigs lowering toward the evening,
especially for the KBGR and KBHB areas.
SHORT TERM: IFR conditions in low clouds and rain are likely
Downeast Tuesday night with VFR conditions persisting across the
north. VFR conditions are expected over the north on Wednesday
with IFR conditions improving to MVFR then VFR Downeast. VFR
conditions are expected Wednesday night, possibly lowering to
MVFR over the north. MVFR to occasionally VFR conditions are
likely Thursday in variable mid and low clouds. Conditions may
lower to IFR across the area Thursday night as a cold front
pulls through with showers and isolated thunderstorms. A return
to VFR conditions is expected on Friday.
NEAR TERM: The wind and seas are expected to remain below small
craft advisory levels through Tuesday.
SHORT TERM: East southeast winds may approach 25 kt Tuesday
night as low pressure tracks south of the waters. Winds should
then be below SCA Wednesday through Friday.
ME...Freeze Warning until 8 AM EDT Tuesday for MEZ002-006.
Frost Advisory until 8 AM EDT Tuesday for MEZ005-010.
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1158 PM EDT Mon May 27 2019
Midlevel low pressure will drive along the I 69 corridor late
tonight resulting in widespread precipitation to Southeast Michigan.
925-700mb warm air/moisture advection has increased significantly the
past few hours. Elevated instability will provide impetus for some
scattered thunderstorm activity, but confidence is too low to
explicitly mention at this time. East wind will veer to the south
with the low overhead, then become northwesterly as the low passes
to the east. Shallow cold advection in the wake of the system will
lead to relatively stable conditions on Tuesday. Boundary layer
cloud is expected to hold firm with breezy west winds of 10 to 20
For DTW...Elevated thunderstorm activity is expected between 03-07Z.
Concerns at this time are limited to heavy rainfall.
.DTW THRESHOLD PROBABILITIES...
* Low in thunderstorms impacting the terminal 06-07Z.
* High in ceilings aob 5kft tonight and Tuesday.
Issued at 1027 PM EDT Mon May 27 2019
The severe thunderstorm threat has ended for Southeast Michigan this
evening. Deep convection that initiated in northern Illinois late
this afternoon was directed southeastward along the composite
925-850mb instability gradient. Not a real surprise with the storm
motion following directly to the corfidi vector. Interruption of
northward moisture transport has occurred with RAP based mesoanalysis
showing little to no MUCAPE over southeast Michigan at this hour.
Given increasing cyclonic flow due to the deep midlevel low pressure,
elevated instability will advect northward. However, stout easterly
surface flow and column overturning due to homogeneous moist
adiabatic shower activity will preclude an organized severe
thunderstorm threat. Thunderstorm mention will remain in the forecast
with shower activity expected to fill in/impact the area between
Issued at 337 PM EDT Mon May 27 2019
A pleasant Memorial Day as good deal of sunshine today has
allowed temperatures to climb into the low to mid 70s away from any
Lake Huron/Erie influences. Shower and thunderstorm chances will
rapidly increase this evening however.
Good max height fall center/surface low pressure tracking through
the Midwest this afternoon, with moisture plume (PW values 1.25-
1.50 inches) tracking up through the Plains and arching over into
Lower Michigan this evening.
The storm system over the Midwest has more or less peaked out, as
the shortwave approaching Lake Superior forces the system off to the
east. The strong low level jet will be quickly veering around
to due westerly toward 12z Tuesday, making it difficult to get
the max instability axis/steeper mid level lapse rates (7+ C/km)
much past the southern Michigan border. Thus, any severe threat
should remain south of M-59, even with the surface low expected to
track close to the I-69 corridor early tomorrow morning. Hail
and heavy rain look predominantly the main threats, as 900-850 MB
computed capes potentially exceed 1000 j/kg (per NAM/RAP). Very
steep surface/near surface inversion developing overnight will
make it very difficult to transport stronger winds to surface,
except right toward the southern Michigan border where some surface
based instability may sneak in, especially if activity arrives
sooner. High degree of 0-1 KM bulk shear along border could also
support rotation, but better chance of tornado certainly south of
state line, away from the cooler easterly flow off Lake Erie.
Going to carry highest pops around midnight with the lead
moisture surge, but by no means a slam dunk for widespread pops, as
heaviest rain likely falls south of the Michigan border within the
sharp instability gradient and closer to the 70 degree dew pts.
Subsidence wake/mid level dry slot behind MCV will limit the
thunderstorm potential on Tuesday, and by the time we recover,
surface front and max instability axis likely suppressed far enough
south were severe storms most likely confined to Ohio (supported
both by ARW and NAM), with upper level confluent flow/low level
drying and surface high pressure building into the Central Great
Lakes late in the day and holding through Tuesday night, as stable
low levels should be present with showalter index in the upper
Yet another strong upper wave/low to lift out of the Four Corners
region, tracking through the Midwest on Wednesday. Frontal boundary
in close enough proximity to allow for good moisture transport during
Wednesday to support showers and possible thunderstorms.
The upper low will dampen with time as it interacts with a broad
upper trough over northern Quebec. This will provide ample forcing
across the region for another a good chance of light to moderate rain
on Thursday and perhaps a few storms, though there looks to be a
fair amount of stability in the column. A weak cold front will push
south through the course of the day and shunt most of the
forcing/rain to the south and east by evening. Dry weather will
follow for much of the weekend and early week as a split flow pattern
develops aloft. Only a low-end chance of showers on Saturday night
into Sunday as an upper trough and associated cold front push
through, otherwise high pressure will keep conditions mostly quiet.
Highs Thursday and through the weekend and early week will generally
reach the upper 60s to lower 70s.
East to northeast flow will gust into the 20 to 25 knot range at
times over/near Saginaw Bay and Small Craft Advisories will remain
in place through Tuesday afternoon. Elsewhere, winds generally at 10
to 15 knots late today, but increase some into Tuesday. An elevated
frontal boundary will lift across lower Michigan tonight and bring
the potential for thunderstorms overnight into Tuesday. To the
south, moderate southwest to west winds will exist over lake St
Clair and lake Erie on Tuesday. An unsettled pattern will maintain
the potential for thunderstorms Wednesday and Thursday.
An elevated warm frontal boundary lifting across lower Michigan will
result in scattered to numerous showers and thunderstorms tonight
through Tuesday morning. While greater potential for heavy rainfall
is currently forecast to remain south of the area, the possibility
for localized areas of heavier rain will exist. Basin average
rainfall totals between one quarter and one half inch can be
expected, but with locally higher totals in excess of an inch
possible. This may result in some flooding concerns for urbanized
and poor drainage areas.
Renewed shower and thunderstorm development may occur again Tuesday
afternoon and evening as a frontal boundary settles southward across
the region. Once again, greater focus for heavier rainfall will tend
to exist to the south, but some localized higher rainfall amounts
are possible within any thunderstorm activity. An unsettled pattern
will maintain the potential for thunderstorms, with an accompanying
localized heavy rainfall threat, both Wednesday and Thursday.
MI...Lakeshore Flood Advisory until 5 PM EDT Tuesday for MIZ048-049-054.
Lake Huron...Small Craft Advisory until 5 PM EDT Tuesday for LHZ421-441.
Small Craft Advisory until 4 AM EDT Tuesday for LHZ422.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
You can obtain your latest National Weather Service forecasts online
Area Forecast Discussion
National Weather Service Quad Cities IA IL
905 PM CDT Mon May 27 2019
Issued at 855 PM CDT Mon May 27 2019
Chance for showers and storms will remain tonight ahead of a cold
front as it pushes south, with the best chances south of I-80
within zone of weak WAA. Still sufficient shear and instability
to support severe wx potential (large hail/winds), but weaker
forcing should keep this threat isolated. Front should exit the
southern counties by tomorrow morning before turning stationary
providing additional storm chances and severe potential Tuesday
into Tuesday night.
Issued at 347 PM CDT Mon May 27 2019
18Z surface data has a low along the IA/MN border northwest of KMCW.
A warm front extended east from the low and then southeast from near
KDEH into northern Illinois. The cold front ran south and then
southwest from the low into southeast Nebraska and Kansas. Dew
points were in the 40s and 50s from the northern Plains into the
Great Lakes. South of the warm front and east of the cold front dew
points were in the 60s to near 70.
.SHORT TERM...(This Evening through Tuesday)
ISSUED AT 347 PM CDT Mon May 27 2019
Some diurnally driven convection should fire west of the Mississippi
through sunset that will result in isolated to scattered storms
especially as the cold front moves into the area. RAP trends are
suggesting considerable sinking air across Iowa which `may` keep
much of the area west of the Mississippi dry late this afternoon and
East of the Mississippi the strong to severe convection will exit
the area through sunset.
After sunset the cold front may help initiate more thunderstorms
south of I-80 that may persist near the front through sunrise
On Tuesday the CMC is suggesting an organized thunderstorm complex
will roll across the area. If this scenario occurs, the warm front
would remain stalled near the IA/MO border before surging north in
The other models have no organized thunderstorm complex but vary on
when the front will move back north.
Regardless, thunderstorms will be seen again on Tuesday with storms
being the most numerous from mid-afternoon through the evening hours.
The presence of the warm front along with strong winds aloft will
provide a favorable environment for severe storms. The amount of
daytime heating and the position of the front will be key factors
regarding the overall severe potential during the afternoon and
.LONG TERM...(Tuesday Night through Monday)
ISSUED AT 347 PM CDT Mon May 27 2019
Assessment...high confidence on storms. Low on rainfall amounts
Storms that develop Tuesday afternoon have the potential to organize
into a storm complex that slowly moves east. The amount of moisture
streaming north into the area will provide plenty of fuel to
generate heavy rainfall.
The model consensus has categorical pops for Tuesday night.
Lingering rain from the previous night will continue during the
morning hours on Wednesday. The amount of new development that
occurs Wednesday afternoon will depend upon the amount of daytime
The model consensus has slight chance to chance pops for the area.
Wednesday night and Thursday
Areal coverage of storms will increase Wednesday night as the next
surface low moves east through the area. Boundaries left over from
the overnight storms will provide the focus for new storm
development on Thursday.
The model consensus has chance to likely pops Wednesday night and
Thursday morning with the highest pops east of the Mississippi. For
Thursday afternoon the model consensus has chance pops for the
Thursday night on...
Lingering convection from the day Thursday will continue into the
evening hours before dissipating. The model consensus has slight
chance to chance pops Thursday evening with mainly dry conditions
Friday and Friday night
Assessment...medium to high confidence
The model consensus has high pressure moving across the area
creating dry conditions. Temperatures should be near normal.
Saturday through Monday
The global models diverge with their respective solutions in terms
of the sensible weather. There seems to be some agreement that
temperatures will be around or slightly above normal.
The ECMWF brings an upper level disturbance through the area
Saturday and Saturday night producing rain while keeping the Sunday
through Monday time frame mainly dry.
The FV3 is similar to the ECMWF in bringing an upper level
disturbance through the area Saturday and Saturday night. However it
does generate diurnal convection on Sunday and Monday.
The GFS brings the upper level disturbance through Saturday
afternoon and night, slightly slower than the ECMWF. However like
the FV3 it generates diurnal convection on Sunday and Monday.
The CMC global has no upper level disturbance and only generates
some diurnal convection Saturday and Sunday. Unlike the other global
models, the CMC global bring a cold front through the area on Monday
and generates convection along it.
Given the differences the model consensus has slight chance to
chance pops from Saturday through Monday.
.AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening)
ISSUED AT 628 PM CDT Mon May 27 2019
VFR conditions with scattered convection will persist through
03z/28 before dissipating. A cold front moving through eastern
Iowa and northern Illinois tonight may allow new convection to
develop near KBRL. Behind the front the VFR conditions are
expected to deteriorate to MVFR. After 19z/28 diurnal convection
is forecast to develop across eastern Iowa and northern Illinois
that has the potential to be severe.
Issued at 842 PM CDT Mon May 27 2019
Some big changes this evening to tributary forecasts. Forecasts
have come in considerably lower on much of the Cedar and Iowa
Rivers, and portions of the Pecatonica, Rock and Green Rivers
due to lower predicted rainfall. This has resulted in the
cancellation or reduction in flood category for many forecast
points within these aforementioned basins. In addition, due to the
lower tributary input crest levels have been lowered by around a
half a foot on the Mississippi River from the Quad Cities LD15 to
Previous discussion Issued at 1236 PM CDT Mon May 27 2019
Looking ahead, quieter weather looks to make a brief return to the
region by mid week. While chances for precipitation still exist for
Wednesday and Thursday, there is high confidence that rainfall
amounts will be light. By Friday, much of the region will be dry.
There are signals in the last model runs that hint at active weather
returning across the area by the weekend. However, confidence on
rainfall amounts and how this would affect river forecasts is low.
As mentioned in previous discussions, we urge people with interests
in the rivers to stay in tune with the latest information.
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
616 PM CDT Mon May 27 2019
Issued at 329 PM CDT MON MAY 27 2019
A slightly disorganized synoptic pattern has made for a difficult
forecast today into tomorrow with many mesoscale features in play.
Currently a low pressure system over IA has formed a surface
convergent boundary down through southeast NE that continues into KS
becoming a warm frontal boundary closer to Colorado. This is a
boundary that will need to be monitored closely over the next 36
hours as it will become the primary forcing mechanism for nocturnal
storm development tonight and severe weather potential tomorrow
afternoon. HiRes models this afternoon are depicting some surface
convergence over northern Missouri which could provide just enough
forcing for some scattered showers and isolated storms this
afternoon. The window for this to occur seems relatively shortlived
as noticeable warming in the mid levels from an induced ridging
ahead of the main shortwave in the Rockies will help provide some
subsidence to the area and keep storm chances at bay later this
afternoon. Before this happens though this convergent boundary will
need to be watched as around 1500 J/kg of MLCAPE and 45kts of
effective bulk shear are available if storms do initiate. Also there
is some low level shear in place so all storm modes would be in play
if something was to develop from now until around 5-6pm. After 6-7pm
this mid level subsidence should help to decrease any severe threat
shifting things to more of a hydro threat as the LLJ develops over
Just after midnight the warm front over KS will shift east with
the quasi-stationary boundary extending across northern Missouri.
Decent isentropic accent along this boundary will likely develop
elevated storms. The main threat with these storms will be flash
flooding from heavy rain and possible training storms along the
boundary. As the LLJ shifts to the east this development could
intensify over an area that has very saturated soils and flash flood
guidance of only around 1-2". With that area getting almost 3-6" of
rainfall in the last 3 days it will not take much for flash flooding
to occur, which is why the flash flood watch was extended through
Wednesday morning. This nocturnal thunderstorm development and
associated cold pool with become a big player in the severe weather
potential tomorrow and where the warm front will finally settle in
the afternoon. Most CAM guidance has this boundary stalling just
north of HWY 36 which would drape a warm front right across our area
as the synoptic set up becomes more favorable for severe weather
Tuesday afternoon with an approaching shortwave trough.
Low level cloud coverage will likely be widespread tomorrow
morning which could inhibit us to destabilize until later in the
day. The mid level warming and elevated mix layer will also be in
play tomorrow afternoon adding to another complication for severe
weather. Soundings from the 18Z HRRR and latest NAM indicate there
will be enough lifting from the approaching shortwave to break
the cap as diurnal heating helps stretch the atmosphere from the
bottom. Models do tend to try to break out of stratus decks by mid
afternoon so the window for severe weather tomorrow looks to be
short-lived and later in the afternoon. I feel the 18Z HRRR might
be under forecasting this low cloud deck which would make MLCAPE
values actually be lower than it is predicting currently. SRH
0-1km helicity will be favorable around the warm frontal boundary
so this will be the location for the greatest tornado threat.
Uncertainty in where the boundary placement which could be from
central MO up into IA depending on what happens tonight makes it
difficult to confidently say where and what type of severe weather
is possible tomorrow. Overall I feel the severe weather threat
tomorrow looks less likely than it has over the last few days with
so many conditional things that need to occur for it to pan out.
That being said, training storms along the warm frontal boundary
over northern Missouri could be devastating to an area already
covered in standing water and may be the most severe impact we see
from this system. 2-3" of rainfall with the possibility of more
if training storms move over the same location.
Since models have slowed down that low pressure system Tuesday into
Wednesday our dry day on Wednesday looks to not happen as much,
especially out east. Remnant showers in the morning over central Mo
are possible and then a shortwave trough riding over the stalled
cold front will provide storm chances again late in the afternoon
into the evening timeframe, mainly east of I-35. Models have trended
drier going into next weekend with maybe the next real rain chances
being Sunday into Monday, but confidence is low in these solutions
as they have shifted everyday this week.
.Aviation...(For the 00Z TAFS through 00Z Tuesday Evening)
Issued at 616 PM CDT MON MAY 27 2019
Isolated thunderstorms have failed to materialize this afternoon
over the Kansas City Metro TAF locations while a couple of showers
have begun to pop up further north near KSTJ where instability is
more favorable for thunderstorm development. Expect MVFR ceilings
and LLWS to develop overnight with MVFR conditions continuing
throughout tomorrow. Finally, thunderstorms, possibly severe,
will impact all TAF sites tomorrow afternoon and into the evening.
MO...Flash Flood Watch through Wednesday morning for MOZ001>008-
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1004 PM CDT Mon May 27 2019
.UPDATE... /REMOVED TS CHANCES FROM VAL VERDE COUNTY/
A quick update was sent to monitor sky, temp, dewpoint trends which
are generally on track from the afternoon package. Main update item
is to take out the thunder over the far western areas as the Burro
Mountain activity has underperformed the past two evenings. 00Z runs
that have arrived hint at a few sprinkles developing near daybreak
Tuesday for the Rio Grande Plains, as morning pwat values push toward
2 inches. However, based on the NAM & RUC forecast soundings, expect
the level of instability to be too elevated for a significant amount
of rainfall rates beyond a random sprinkle. Thus the periods outside
of tonight were unchanged.
.PREV DISCUSSION... /ISSUED 602 PM CDT Mon May 27 2019/
Convection has had a hard time getting going west of the Rio Grande
and will remove the mention of VCTS for DRT this evening. Otherwise,
another round of MVFR stratus is expected tonight with an onset time
around 5-6z for the I35 sites and a few hours later for DRT.
Conditions will improve around the late morning hours. Otherwise,
breezy southeasterly winds will continue through the valid period.
The DRT ASOS remains down and the TAF will not be amended until it
comes back up.
PREV DISCUSSION... /ISSUED 314 PM CDT Mon May 27 2019/
SHORT TERM (Tonight through Tuesday Night)...
Morning radiosonde observations from Del Rio and Fort Worth showed a
70-75 knot upper level jet bisecting the state and a cirrus canopy
streaming out of Mexico this afternoon is doing a good job marking
where this feature is located. While some of this cirrus had impeded
convective development over northern Coahuila midday, deeper
convection was beginning to bubble up beneath this canopy along the
higher terrain. High resolution guidance remains fairly consistent in
bringing a few thunderstorms east off the higher terrain during the
evening hours and have expanded rain chances along the Rio Grande
tonight as a result. Still expect capping east of the Rio Grande to
limit how far into the region this activity will make it, but steep
mid-level lapse rates, dew point depressions close to 20 degrees near
the Rio Grande, and increased forcing for ascent with the presence
of this small jet streak may allow for a thunderstorm or two to
become strong or severe as it moves east towards the Rio Grande.
Large hail and gusty winds may be possible with stronger storms. Most
of this activity is expected to dissipate with loss of heating later
A lee side surface low in Colorado early this afternoon will result
in breezy southeasterly winds persisting across South Central Texas
through the short term forecast. Not only will this keep humid
conditions in place across the region with dew points struggling to
mix out of the mid 60s to mid 70s, but this will allow for another
round of overnight stratus to spread into the region. A few streamer
showers will also be possible during the morning hours across the
Coastal Plains. After a warm and humid start Tuesday morning with
temperatures in the upper 60s to mid 70s, expect afternoon highs to
range from the mid 80s in the Hill Country to upper 90s in the Rio
As a closed upper low nearing the Four Corners this afternoon crosses
the Rockies Tuesday night, the Colorado surface low is expected to
eject across the Central Plains and drag a cold front into the Texas
Panhandle. A secondary disturbance following the upper low Tuesday
night may provide enough lift ahead of this cold front for a few
thunderstorms to develop across parts of West Central or Southwest
Texas, but with the main forcing well north and west of the region
during this time only highlighting 20 PoPs across the Edwards Plateau
and into the Hill Country. Farther east, moisture advection
associated with southeast flow may again produce a few streamer
showers across the Coastal Plains. Very warm temperatures are
expected again Tuesday night with lows in the upper 60s to mid 70s.
LONG TERM (Wednesday through Monday)...
Thunderstorms ongoing across portions of West Central or Southwest
Texas Wednesday morning are expected to spread along the southward-
moving cold front as the secondary upper disturbance lifts into the
Southern Plains. As a result, highest rain chances will remain north
of the region on Wednesday as the front drops across North Texas.
Guidance has remained consistently inconsistent in how far south the
front will move on Wednesday, with the Canadian bringing the front
almost all the way through the region by Wednesday night, the
European sliding the front into the Hill Country, and the GFS keeping
it north of the region. What does appear consistent is the amount of
modification of the airmass behind the front and thunderstorm
development along the front will be the primary drivers in how
quickly the front reaches South Central Texas. Because of the time of
year (warmer ground temperatures aiding in near-surface modification
of the post-frontal airmass) and expectation for thunderstorm
activity along the front to be ongoing well north of the region, have
trended with a more conservative/slower frontal approach with the
front not expected to reach the region until Thursday. Adjustments to
frontal timing are expected through the next forecast iterations
however as more data becomes available. With the front expected to
stay north of the region on Wednesday, expect scattered diurnally
driven showers and thunderstorms generally north of Interstate 10
with highs in the mid 80s to mid 90s.
Expect the front to continue to make slow progress into the region on
Thursday, potentially stalling somewhere across the Hill Country and
resulting in chances for scattered showers and thunderstorms within
the vicinity of the boundary. Rain chances will continue to linger
into the Thursday night and Friday period as the frontal boundary
slowly loses definition. Will have to keep an eye on where the
boundary is located within the Thursday night and Friday morning time
period. The deterministic GFS and (to a lesser extent) the Canadian
are attempting to develop a thunderstorm complex along the frontal
boundary in Southwest Texas that may be capable of producing locally
heavy rain near the Edwards Plateau. Otherwise, upper ridging begins
to build into the region during the upcoming weekend and results in
a warming and drying trend for South Central Texas.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 73 90 75 89 72 / 10 10 20 40 40
Austin Bergstrom Intl Airport 73 91 75 89 72 / 10 10 20 40 40
New Braunfels Muni Airport 73 92 75 90 73 / 10 10 20 30 30
Burnet Muni Airport 71 88 74 87 70 / 10 10 20 40 50
Del Rio Intl Airport 75 94 75 94 74 / 10 10 10 - 20
Georgetown Muni Airport 73 90 75 88 71 / 10 10 20 40 40
Hondo Muni Airport 73 93 75 92 74 / 10 - 20 20 30
San Marcos Muni Airport 73 90 75 88 72 / 10 10 20 30 30
La Grange - Fayette Regional 74 91 77 89 74 / 10 10 20 30 40
San Antonio Intl Airport 74 91 76 89 74 / 10 10 20 30 30
Stinson Muni Airport 74 93 76 91 75 / 10 - 20 30 30
Area Forecast Discussion
National Weather Service Hastings NE
700 PM CDT Mon May 27 2019
.SHORT TERM...(This evening through Tuesday)
Issued at 456 PM CDT Mon May 27 2019
Main concern is potential for severe thunderstorms as well as
additional heavy rain and the impact to ongoing flooding.
Has been a fairly quiet day weather-wise, especially compared to
12-18hrs ago. Currently, temps are in the 70s to near 80 under
p cldy skies. Looking regionally, last night`s MCV/shortwave can
be seen over E IA, with a trailing cold front/outflow extending to
the SW to near OMA-HJH-HYS. S of this boundary, sfc Tds are in the
mid to upper 60s. Scat intense convection has developed over the
central High Plains in an area of upslope flow, weak-moderate
instability, and strong deep layer shear.
Strong to severe tstms still look like a possibility later this
evening and overnight, though the exact placement and evolution
still remains uncertain, even at this close of time range. I
currently envision two most plausible scenarios (or a combination
of the two) for our severe potential:
Scenario 1) elevated convection developing after 03Z on the nose
of 50-55kt LLJ near and north of a warm front. This activity
would be fed by large reservoir of high theta-e airmass currently
over KS/OK with steep mid-level lapse rates contributing to MUCAPE
of 2000-3500 J/kg. Latest HRRR/RAP forecast soundings along with
latest SREF indicate effective deep layer shear will be more than
favorable for large hail potential, generally on the order of
40-60kt. There is some disagreement on location of the nose of
LLJ/warm frontal placement and resultant QPF. Last several runs
of HRRR as well as NAM suggest main area from Hwy 6 to I-80, but
RAP has been along and just S of the state line. RAP appears to be
a bit of an outlier attm. Individual cells would move SW to NE
with the overall development zone shifting N with the LLJ
Scenario 2) Convection developing over the High Plains moves E
through W Nebraska this eve, then arrives in W CWA 03Z-06Z and is
fed by developing LLJ. Several CAMs suggest this would arrive as
linear features with perhaps embedded supercell structures near
the boundary. In theory, this activity could have more of a
damaging wind threat and perhaps a tornado or two as well, but the
stabilizing boundary layer argues otherwise. Models keep this
activity moving along a rather quick pace to the E, which would be
good for hydro reasons.
Overall, the shear/instability parameter space will likely be
favorable for strong to severe storms tonight, whether it be from
scenario 1 or 2, or a combination of the two. Hydro certainly
remains a concern as well. Please reference the dedicated
Hydrology section below for additional details.
Activity should weaken and focus further E with time, coincident
with a weakening and veering LLJ.
There`s potentially another round of severe convection in store
for portions of the area Tuesday afternoon into early evening,
though these details will largely depend on how activity unfolds
tonight. In general, models have been trending further S with the
sfc triple point and warm front and now track these features near
and especially S of Hwy 6, potentially right along the state line.
The 12Z NAM places the sfc low/triple point near Red Cloud, NE by
21Z. Areas along/S of warm front and E of trailing dry line would
be most favorable for potential sfc based tstm development in the
aftn. It is increasingly likely that areas along and N of I-80
remain in the cold sector of the system under the influence of
moist, easterly upslope flow and thick low clds. However, a couple
of the CAMs (namely the ARW) track what would likely be some
slightly elevated supercells NE of the sfc low across the NE
quadrant of the CWA. While not likely, this can not be completely
discounted either. All of this depends on the speed of the upper
system and current timing remains on track such that any risk for
severe weather looks to remain largely confined to areas E of Hwy
281. It is possible most of the convection fires just E of the CWA
altogether, but with several model solutions keeping the triple
point in the SE CWA at 21Z, not ready to downplay svr potential
As far as severe threats: CAPE/shear once again looks favorable
for supercell structures Tue PM. Large hail would be main concern
for areas N of I-80 and E of Hwy 281. All modes of severe would be
possible for SE quadrant of CWA, including a couple tornadoes,
due to backed winds along warm front contributing to locally
elevated 0-3km SRH values of 150-250 m2/s2. The main severe
threat will quickly shift E Tue eve, but the upper low will remain
in close proximity to continue at least a chc for shwrs/tstms
into Tue night, esp for areas N of I-80.
Finally, high temps on Tue are tricky. Continued trend of mid
shift of decr highs, esp for areas from the Tri-Cities N and W, as
low clds and E wind are more likely. Highs may still be too warm
along Hwy 6 corridor, as current values are predicated on seeing a
few hrs of sun in the aftn, which is uncertain. Right now, highs
range from near 60 at Ord, to 82 near Beloit.
.LONG TERM...(Tuesday night through Monday)
Issued at 456 PM CDT Mon May 27 2019
With the main forecast concerns in the Short Term, not much time
spent on the Long Term portion of the forecast. In general,
though, expect a cooler, but still somewhat active, pattern for
mid-week. Warmer temperatures are more zonal flow with low-end
pcpn chances arrive late week and continue into next weekend.
Models have trended slower and more strung out with the departing
trough Tuesday night into Wednesday. In fact, nearly all the
models now keep cyclonic mid to upper flow around through Thu. So
what once looked like a few days of dry weather now look off an on
wet, particularly for northern 1/2 to 2/3 of the CWA. Models
differ on specifics, like how much QPF to expect, with GFS wetter
compared to NAM/EC. Eventually, should see the low pressure
weaken/move ENE and allow for shortwave ridging to move in for
Fri, and perhaps Sat. General consensus is that upper pattern
should become fairly zonal next weekend, with multiple small
perturbations moving through. Low level moisture and instability
should also increase, so off and on scat tstms will be possible.
Zonal patterns don`t lend much predictability for specifics, so
far too soon to determine severe potential.
Temperatures: combination of cool northerly flow, cld cover, and
possible pcpn will keeps temps on the seasonably cool side Wed
into Thu. Axis of high pressure shifts E on Fri, allowing for
return to srly flow and warmer mid-level temps. Expect fairly
seasonable temperatures next weekend.
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday)
Issued at 659 PM CDT Mon May 27 2019
Main issue will be lowering ceilings with time. Models are
consistently forecast this, and feeling more confident of IFR
ceilings by Tuesday morning.
Issued at 456 PM CDT Mon May 27 2019
Hydro remains a concern mainly tonight, and over the far SE on
Tuesday. Have held off on issuing a Flash Flood Watch for now for
a few reasons, some of which are uncertainty in location of
tonight`s tstms, faster storm motions, and lesser coverage. There
is less upper forcing for widespread and continuous convection
like last night, and latest CAMs keep storms moving along at a
nice pace. Think areal average of 0.50-0.75" across south central
NE is most appropriate attm. With that said, would not at all be
surprised to have additional hydro issues tonight, on at least an
isolated basis, as FFG values are low in areas that received hvy
rn last night, mainly from Alma to Hastings to Aurora to Osceola.
So some heavy cores passing over these areas could easily cause
additional flooding or worse ongoing flooding. If confidence
increases this eve on intensity and placement of strongest
convection, then a Flash Flood Watch may be needed.
Can`t rule out some hydro concerns over the far SE Tue aftn, but
the relatively small window for storms should keep the threat
Area Forecast Discussion
National Weather Service Marquette MI
627 PM EDT Mon May 27 2019
.SHORT TERM...(This evening through Tuesday)
Issued at 416 PM EDT MON MAY 27 2019
WV imagery and RAP analysis indicated a mid level low over northern
AZ and a broad ridge over the se CONUS resulting in wsw flow from the
central Plains to the western Great Lakes. A well defined shortwave
located over sw WI supported a large area of rain from se MN through
WI and Upper Michigan. Much of the rain through Upper Michigan was
supported by 700-500 mb fgen while the heavier showers over WI were
associated with stronger 850-700 mb fgen and low level moisture inflow.
Tonight, radar/satellite trends along with short range models
suggest that the rain will continue across Upper Michigan through
this evening and taper off overnight. The heaviest rain will also
remain across the south in line with the stronger low level fgen,
with rain amounts to around an inch. Over the north amounts should
remain in the 0.25-0.50 inch range, except over the Keweenaw where
under a tenth of an inch is expected. The pcpn will taper off to
scattered showers over the east half late.
Tuesday, some light rain or drizzle may linger over the north and,
especially over the higher terrain, where abundant low level
moisture lingers along with upslope nne low level flow. Although
there may be partial clearing by afternoon, especially over west,
925-700 moisture forecasts suggests clouds will linger over most of
the area. This should keep temps closer to the lower end of guidance
with highs in the low to mid 60s inland and around 50 near Lake
.LONG TERM...(Tuesday night through Monday)
Issued at 305 PM EDT MON MAY 27 2019
Beginning Tuesday night through the end of the work week, with large-
scale pattern will consist of a closed low over Hudson Bay that will
slowly push into northern Quebec on Thursday, with generally split
flow over the NW CONUS as a weakening cutoff low over the Plains
opens and eventually phases with the low over Quebec. The associated
surface low will remain well to our south, so in terms of sensible
weather Upper Michigan will remain dry with seasonal temperatures. A
shortwave and associated surface low will approach from the NW on
Friday evening will bring chances for showers and perhaps a
thunderstorm or two that may continue into Saturday before
conditions look to dry back out Sunday and Monday. It is worth noting
that model agreement is much better through the forecast period than
it has been over the past several days.
Largest changes made to the blends were daytime dew points on
Wednesday and Thursday. With a dry airmass overhead, GFS forecast
soundings indicate the potential for the mixed layer to extend to 7-
8 kft on Wednesday, although the NAM is not quite that bullish.
Similarly, the GFS would bring sfc dew points down well into the 20s
Thursday. Not quite ready to bite on that solution yet, but did a
50/50 blend of the mixed dew point tool with the superblend to get a
closer idea of how dry the surface will get these two days.
Currently, the forecast is for minRH values to fall to the lower 30s
both days. Winds should be relatively light on Wednesday but may
become gusty over the east on Thursday with the passage of a cold
front in the afternoon, so after a few dry days elevated fire
weather conditions may be possible.
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 626 PM EDT MON MAY 27 2019
Conditions will fall to IFR at CMX tonight with upslope east flow
developing this evening. IWD and SAW will stay IFR overnight in
moist upslope flow. Conditions improve at all sites in the afternoon
with drier air moving in.
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 416 PM EDT MON MAY 27 2019
Low pressure sliding from northern Iowa to southern lower Michigan
will bring a gradual decrease in ne winds, especially over the west
end of Lake Superior where winds were gusting in the 20-30 knot range.
Winds will be under 20kt across the rest of the lake. By late
tonight and through the mid and late week period winds should be
generally under 20kt.
Area Forecast Discussion
National Weather Service Nashville TN
934 PM CDT Mon May 27 2019
Middle Tennessee remains influenced by a large upper-level high
pressure system centered over the southeastern U.S. Perhaps the
greatest evidence of this is our continued pattern of mainly dry
weather. Over the past two weeks, Nashville International Airport
has received a mere 0.21 inches of rainfall and we remain nearly
3.25 inches below normal for the month of May.
Rain chances will exist over the next few days, but they will
remain meager with locations TBD. The GFS and HRRR advertise a
subtle wave of mid-level energy that may sneak into our CWA
Tuesday afternoon. Pending that this energy materializes, it would
be enough to spark a few showers and isolated storms. Slight chance
PoPs were added to reflect this potential. Any sum of rain will
be the result of a showdown between the stout high pressure
influence and this subtle wave of energy. Otherwise, temperatures
will be a degree or two cooler, topping out in the upper 80s and
low 90s. The rest of the forecast remains on track.
00Z TAF DISCUSSION.
VFR conditions will continue through this period. Scattered
cumulus will dissipate this evening, as will the gusty southwest
winds. Winds and clouds will increase again through the day on
Tuesday...SW winds gusting to around 15 kts.
.PRELIMINARY POINT TEMPS/POPS...
Nashville 70 92 71 93 70 / 0 10 10 10 10
Clarksville 69 89 71 90 69 / 0 10 10 10 10
Crossville 65 85 64 86 65 / 0 10 10 10 10
Columbia 67 90 68 92 68 / 0 10 10 10 10
Lawrenceburg 68 90 69 91 69 / 0 10 10 10 10
Waverly 69 90 70 90 69 / 0 10 10 10 10
Area Forecast Discussion
National Weather Service Pendleton OR
739 PM PDT Mon May 27 2019
.SHORT TERM...Tonight and Tuesday...Shower activity and
thunderstorms are beginning to decrease as sunset approaches so
updated forecast to reflect this. Will continue to see a decrease
with showers ending overnight but still lingering clouds left over.
Same pattern will exist on Tuesday so expect a basic repeat of
showers building in the afternoon mainly over the mountains and a
slight chance of thunderstorms.
.PREV DISCUSSION... /issued 300 PM PDT Mon May 27 2019/
SHORT TERM...Tonight through Thursday...The closed low that has
brought showers and thunderstorms the past several days is now
approaching the four corner states and is weakening. There is a
broad circulation and multiple embedded waves associated with the
low. Water vapor shows one wave moving south across western OR and
a weaker wave near Lewiston tracking to the southwest. These two
upper level disturbances will bring an increasing chance of
showers and thunderstorms across central and northeast Oregon and
far southeast Washington late this afternoon and evening. All
zones have at least a slight chance of showers and thunderstorms
early this evening as the atmosphere destabilizes, but the main
focus will be the areas affected by both disturbances. The HRRR
has done a decent job the past couple of days on location and
storm strength, and it has been consistent showing the strongest
cells moving across Bend between 4 PM-6 PM, although any
thunderstorms should be short lived and weak. Showers will taper
off and thunderstorms will end after sunset. One minor change to
the forecast was to increase PoPs slightly in our far eastern
zones after midnight, as the GFS and NAM12 hint at another
embedded disturbance that could bring widely scattered showers.
On Tuesday, the flow will change to a northerly direction, and any
moisture or instability for showers and thunderstorms will be
along the mountains. The convection will primarily be diurnally
driven with weak garden variety thunderstorms. The remainder of
the short term is defined as an unorganized low pressure trough
over the Pacific NW, and the air mass will remain unstable with
steep lapse rates. The best chance of showers and thunderstorms
will be over the Blue Mountains, Wallowas, the John Day-Ochoco
Highlands and adjacent valleys and little to no chance elsewhere.
Breezy winds have been observed today along the Grande Ronde
Valley, Kittitas Valley, the eastern Columbia River Gorge, and
portions of north central Oregon. Winds will diminish tonight but
will increase again in these areas on Tuesday. Wister
LONG TERM...Thursday night through Monday. Upper low over
California and Nevada Thursday night and Friday. Instability
associated with the low may generate scattered showers and
thunderstorms over central and northeast Oregon Thu afternoon and
evening diminishing overnight. This activity may repeat Friday
afternoon and evening. Otherwise partly to mostly cloudy skies.
The low moves off to the east Saturday with a weak ridge building
into the Pacific northwest. Any lingering showers would likely be
Wallowa county east into Idaho. The remainder of the forecast area
will be partly cloudy and warmer. For Sunday into Monday a
stronger westerly flow aloft develops and pushes a short wave
across southern BC and the Pacific northwest. This will bring
increased westerly winds and cooler temperatures. 94
AVIATION...00z tafs. Scattered showers and isolated thunderstorms
through the evening decreasing in coverage after 08z. Ceilings 030-
070. Winds 5-15kt except 15-25kt DLS. For Tuesday sct-bkn 050-100.
Scattered showers and isolated thunderstorms developing mostly over
the mountains in the afternoon. 94
.PRELIMINARY POINT TEMPS/POPS...
PDT 53 78 53 78 / 10 10 10 10
ALW 54 81 55 81 / 10 10 10 20
PSC 59 87 57 87 / 10 0 10 10
YKM 58 84 54 84 / 10 20 0 0
HRI 57 84 56 84 / 10 0 10 10
ELN 54 79 53 79 / 10 20 0 10
RDM 44 76 45 77 / 20 20 10 10
LGD 50 73 48 73 / 20 20 10 40
GCD 48 72 47 71 / 20 20 10 50
DLS 57 78 53 80 / 20 10 0 0
Area Forecast Discussion
National Weather Service Sacramento CA
224 PM PDT Mon May 27 2019
Mainly late-day mountain showers and thunderstorms continue through
the week. Warming temperatures to normal and above normal through the
Showers becoming a little more numerous over Srn ORE and crossing
the CA/OR border at press time as a short wave, rotating around the
backside of the closed low over Srn UT, drops southward towards
Norcal. By 12z Tue, prog charts forecast this feature to be near SAC
or slightly to the SW, so it will be moving over our CWA overnite.
The HREF prob of REFL > 40 dBZ suggests the best chance of thunder
will be over the Shasta Co area through about 8 pm, with much lower
probabilities over Plumas Co and southward to the I-80 corridor near
the Crest. This correlates well with the CAPE/LI forecasts of the
various models as well. The track of the short wave (vort max) also
would warrant a low PoP over the coastal range, but a lot of
uncertainty as to how far south convection will develop. The HRRR
suggests isolated activity may extend towards the I-80 corridor into
Solano Co. along the far west side of the Valley and lee-side of the
In the wake of the short wave dropping southward over the CWA
tonight, skies will clear with Nly winds developing behind it. This
will be trend into Tue morning.
However, the short-term forecast for mainly the higher elevations
will sound like the proverbial "broken record," with chances of
showers/thunderstorms each day. Minimal activity is expected on Tue
as Norcal will be in between upper impulses, the aforementioned
short wave dropping southward from our CWA into SoCal, and the next
upstream short wave moving towards the Pac NW/Nrn CA coast.
Instability progs and the HREF prob of REFL warrant PoPs over the
Sierra from I-80 southward on Tue. Then increasing areal coverage
Wed and even more so on Thu as the upstream trof moves into ORE and
forms yet another closed low which again will drop southward into
our CWA on Thu. Although not as deep/cold as the previous system,
the mid level CAA will steepen lapse rates as the late May sun angle
destabilizes the lower atmosphere.
The most noticeable difference will be the temps as we move rapidly
from unseasonably cool weather to normal, then above normal temps
this week. The departing cold upper low will allow the milder
Pacific air around the Ern Pac ridge to advect ("waft", if you will)
into Norcal. 8H temps will warm into the teens deg C beginning Tue
allowing temps to warm to near normal in the Valley through mid
week. Cloud cover from convective cloudiness over the higher terrain
will limit some of warming there, so temps are likely to continue to
run a few degrees below normal. After the second (not as cold/deep)
upper low drops Swd, even warmer temps are forecast with low 90s
possible in the Valley for the weekend. JHM
.EXTENDED DISCUSSION (Friday THROUGH Monday)
Broad upper troughing remains near 120W through the weekend with
embedded short wave. This will keep an unsettled weather pattern
with a threat of showers and thunderstorms. Best chances will be
in the afternoons to early evenings over the eastern foothills
and mountains. Upper ridging builds into NorCal early next week.
High temperatures expected above normal with a warming trend
through the extended period. By Monday, max temps forecast to be
about 10 degrees above normal with lower to mid 90s in the Central
Valley and mainly 70s to 80s for the mountains and foothills.
Mnly VFR conds ovr Intr NorCal nxt 24 hrs exc isold MVFR/IFR poss
in shwrs or tstm ovr fthls/mtns til 06z. Lcl S-W sfc wnd gsts to
25 kts poss in Cntrl Vly and Delta, and ovr hyr trrn til abt 05z.
Lcl Nly sfc wnd gsts to 25 kts poss in Cntl Vly aft 15z Tue.