Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
235 PM EDT Tue May 13 2025

Valid 12Z Fri May 16 2025 - 12Z Tue May 20 2025

...Heat builds across the southern Plains while late season snow
is expected for the Rockies...


...General Overview...

The strong low pressure system over the northern Plains on
Thursday is forecast to lift northeast across Ontario going into
Friday, with a strong trailing cold front draping through the Mid-
South. Numerous showers and storms are likely along and ahead of
the front from the Mid- South to the Ohio Valley and Great Lakes.
Attention then turns to the Intermountain West by the weekend as
another amplified upper trough and closed low develops and brings
additional rounds of valley rain and mountain snow along with cold
conditions for this time of year. Early season heat will continue
to make weather headlines for the south- central U.S. with an upper
ridge axis governing the overall weather pattern.


...Guidance/Predictability Assessment...

The 12z model guidance suite today continues to offer very good
synoptic scale agreement for the end of the week, with a multi-
deterministic model blend sufficing as a starting point in the
forecast process and slightly more weighting applied to the
ECMWF/GFS solutions. The UKMET remains a bit north of the better
consensus with the Great Lakes low and then later in the period
there are some differences with how this energy may or may not
combine with another shortwave to the north, or the evolution of
this off the Northeast coast. Guidance agrees well with another
trough amplifying over the West this weekend, with an eventual
closed low located over/near the central Great Basin. This low will
eventually lift northward into the north-central U.S. early next
week but with plenty of uncertainty in energy dispersion within and
around low which would have implications on sensible weather
across this region. The WPC forecast trended towards the ensemble
means late period which showed better consistency and smoothed out
the smaller scale differences.


...Weather/Hazards Highlights...

Showers and thunderstorms increase in coverage and intensity
across the Mid-South and Ohio Valley ahead of a cold front that
will be intercepting deeper return moisture. An broad ERO Marginal
Risk area remains valid for Friday (Day 4) from Arkansas to the
central Appalachians, including portions of the Ohio Valley. Going
into Saturday (Day 5) attention then turns to portions of the
southern Plains and extending to the Mid-South with enhanced
moisture convergence near the same frontal boundary and ahead of a
developing wave of low pressure near the Texas Panhandle. Anomalous
moisture combined with low flash flood guidance values across
parts of the Northeast allowed for the introduction of a marginal
risk area on the Day 5/Saturday ERO for this region ahead of a
departing front and redevelopment of low pressure offshore.

Elsewhere across the nation, the Storm Prediction Center is
monitoring the potential for severe weather from the Midwest to the
Mid-South to close out the work week with favorable instability
and kinematics. Across the Rockies, expect additional chances for
late season snow for the central and northern Rockies by Sunday
into Monday as the next upper trough and shortwave moves in, with
the potential for over a foot of accumulation for some of the
highest mountain ranges. At least locally heavy rainfall seems
likely to develop across the Great Basin over the weekend and into
the north-central U.S. early next week in response to the
developing upper low which will continue to be monitored.

Very warm weather will be commonplace across the eastern half of
the country to close out the work week, with highs well into the
80s and even some lower-middle 90s from the Ohio Valley and Mid-
Atlantic southward to the Gulf Coast. Early season excessive heat
is expected across southern Texas through the upcoming weekend with
highs exceeding 100 degrees near the Rio Grande and into much of
central Texas, and HeatRisk reaching the major to extreme category
for some of these areas, with temperatures in the 70s providing
little to no relief overnight. In contrast, chilly conditions are
likely for the Intermountain West and Northern Rockies/Plains with
highs running 10 to perhaps 20 degrees below average with the upper
level trough and increased cloud cover.

Santorelli/Hamrick


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 PM EDT Wed May 14 2025

Valid 12Z Sat May 17 2025 - 12Z Wed May 21 2025

***Heat builds across the southern Plains while late season snow is
expected for the Rockies***


...General Overview...

A well-organized low pressure system that will initially be over
the northern Great Lakes on Saturday will likely develop a triple
point low over New England by Sunday before moving offshore,
bringing widespread rain to the Northeast states. Out West, an
amplified upper trough develops over the Great Basin and this spurs
surface cyclogenesis across the central Plains by Monday,
supporting widespread coverage of showers and thunderstorms from
the western High Plains to the Mid-South to start next week. This
surface low then tracks in the general direction of the Great Lakes
by next Wednesday, while a weaker disturbance affects the
Northwestern states.


...Guidance/Predictability Assessment...

Updated 00/06Z model guidance remains in generally good agreement
regarding the synoptic scale pattern across the CONUS this weekend
and into early/mid-next week. An increasingly amplified pattern is
expected as a leading upper-low over the northeastern U.S. briefly
deepens and lingers over the vicinity, a large-scale trough digs
southward over the West, and a ridge builds northward in between
over the Plains/Midwest. The most significant weather during the
period will likely be tied to the western upper-trough and its
reflection at the surface as a frontal system moves through the
Intermountain West with eventual lee cyclogenesis over the
central/southern Plains during the Sunday-Monday timeframe as the
system emerges onto the Plains. The amplified, blocky pattern will
also result in the slow progression of the individual systems
leading to multiple days of precipitation over the western and then
central U.S., as well as lingering precipitation over the
Northeast this weekend. Guidance then indicates leading energy with
the western trough will eventually lift northeastward over the
Midwest/Great Lakes by mid-week. There is some disagreement on the
timing of potential upstream shortwave energy from the northeastern
Pacific dropping southward over the northwest U.S./southwestern
Canada with a cold front at the surface, though this looks to have
modest sensible weather impacts at this time.

The updated WPC forecast initially uses a composite blend of the
00Z ECMWF/UKMET/CMC and 06Z GFS before removing the contribution
from the CMC given some more significant differences in the
forecast, specifically a faster departure of the upper-low over the
Northeast east into the Atlantic and a more aggressive depiction
of secondary northern stream energy over the northwest/southwestern
Canada. A contribution from the 00Z ECens and 06Z GEFS mean is
added following the removal of the time-limited UKMET given the
typical increasing small-scale differences in the deterministic
guidance. The updated blend not surprisingly maintains good
continuity with the prior forecast given good run-to-run
consistency in the models, with the largest difference in the
updated forecast being a modestly slower northeastward progression
of the central U.S. system from the Plains to Midwest/Great Lakes
by mid- week.


...Weather/Hazards Highlights...

Showers and thunderstorms increase in coverage and intensity from
the southern Plains and extending to the Mid-South over the weekend
with enhanced moisture convergence near a quasi-stationary frontal
boundary and ahead of a developing wave of low pressure near the
Texas Panhandle. The guidance suggests multiple rounds of
convection across the region, but differ on QPF placement, so a
broad Marginal Risk area is valid for portions of this region on
both Saturday and Sunday. Anomalous moisture combined with low
flash flood guidance values across parts of the Northeast allowed
for the continuation of a Marginal Risk area for the Day 4/Saturday
ERO for this region ahead of a departing front and redevelopment
of low pressure offshore, and moisture lingers across eastern Maine
where a Marginal Risk is planned for Sunday.

Across the Rockies, expect additional chances for late season snow
for the central and northern Rockies by Sunday into early next
week as the next upper trough and shortwave moves in, with the
potential for over a foot of accumulation for some of the highest
mountain ranges. Widespread moderate to locally heavy rainfall
seems likely to develop across the Great Basin over the weekend and
into the north-central U.S. early next week in response to the
developing upper low which will continue to be monitored. A
Marginal Risk area is planned for Sunday/Day 5 across portions of
eastern Nevada, southwest Utah, and northern Arizona where slow
moving convection associated with the upper low may result in some
localized flooding across the high desert. Another area of enhanced
rainfall is looking more likely across the northwestern High
Plains on Sunday as well with increased moisture flux to the north
of the developing surface low ejecting east from the Rockies, and a
Marginal Risk area is also planned for this area on Sunday. Expect
both a severe weather and heavy rainfall threat with the Plains
system during the Sunday to Tuesday timeframe given seasonably
sufficient moisture, instability, and shear for May. The severe
weather risk currently looks to be greatest across portions of the
central/southern Plains, with a broader heavy rainfall threat
arcing ahead of the system from the northern Plains southeastward
into the Missouri and Upper/Middle Mississippi River Valleys. Gusty
winds are also likely given the strength of the western system,
particularly over portions of the Desert Southwest Saturday, and
also possibly along the foothills of the Rockies and High Plains
Sunday-Monday.

Early season excessive heat is expected across central and
southern Texas through the upcoming weekend with highs exceeding
100 degrees near the Rio Grande and into much of central Texas, and
HeatRisk reaching the major to extreme category for some of these
areas. This will likely set additional record high temperatures for
these areas, and overnight lows will struggle to fall below 75
degrees for many of these same areas. In contrast, chilly
conditions are likely for the Intermountain West and Northern
Rockies/Plains with highs running 10 to perhaps 20 degrees below
average for many areas from Arizona to Idaho with the upper level
trough and increased cloud cover.

Putnam/Hamrick


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
405 PM EDT Thu May 15 2025

Valid 12Z Sun May 18 2025 - 12Z Thu May 22 2025

...Heat builds across the southern Plains and Florida while late
season snow is expected for the Rockies...


...General Overview...

A transition to a more amplified pattern is expected as a leading
upper low over the northeastern U.S. briefly deepens and then moves
out, a large-scale trough digs southward over the West, and a
ridge builds northward between those troughs over the Plains and
Midwest states. The most significant weather during the period will
likely be associated with the western upper trough and its
reflection at the surface as a frontal system moves through the
Intermountain West. This upper trough will induce lee cyclogenesis
over the central/southern Plains during the Sunday- Monday
timeframe as the system ejects eastward over the Plains. The
amplified, blocky pattern will also result in the slower
progression of the individual systems leading to multiple days of
precipitation over the western and then central U.S., as well as
lingering precipitation over the Northeast this weekend.


...Model Guidance/Predictability Assessment...

Latest model guidance continues to be in reasonable agreement, at
least on the large scale, for the amplifying trough over the West
into early next week, but with some struggle on the details. The
WPC forecast for today went with a general model compromise for the
Days 3 (Sunday) - Day 5 (Tuesday) time period. After this, the CMC
was a little different with the evolution of the trough as it
ejects into the Midwest, with the ECMWF and GFS more consistent
with each other and the ensemble means. Also some significant
timing differences across the Northwest late period with smaller
scale and weaker shortwaves moving through the flow. For this
reason, it seemed best to trend more towards the ensemble means for
the late period, with smaller contributions from the deterministic
ECMWF and GFS. This also maintained fairly good consistency with
the previous WPC forecast as well.


...Weather/Hazards Highlights...

The active weather pattern with the strong surface low developing
over the western High Plains will lead to increasing showers and
thunderstorms for a wide expanse from the Dakotas to the Midwest,
and extending across portions of Texas and Oklahoma. Prolonged
advection of Gulf moisture combined with an increasingly dynamic
late spring storm system will fuel the development of multiple
mesoscale convective complexes, and the greatest concentration of
these will likely be over portions of the middle Mississippi
Valley. A Slight Risk area continues for the Day 4 period Sunday
where the highest confidence exists for excessive rainfall, with
some expansion across Missouri for this afternoons update. For Day
5, also went ahead and upgraded the same general region and into
southern Illinois to a slight risk given the overlap of heavy
rainfall potential with Day 4. Severe thunderstorms are also likely
to develop across portions of the central Plains in association
with this activity.

Elsewhere across the Continental U.S., expect additional late
season snow for the central and northern Rockies by Sunday and into
Monday, with the potential for over a foot of accumulation for
some of the highest mountain ranges of Wyoming and Colorado. For
the lower elevations, a Marginal Risk area for excessive rainfall
will be valid for both Sunday and Monday across portions of the
Four Corners region where slow moving convection associated with
the upper low may result in some localized flooding across the high
desert. Across the Northeast U.S., anomalous moisture combined
with low flash flood guidance values across parts of Maine allowed
for the continuation of a Marginal Risk area for the Day 4/Sunday
ERO for this region owing to re-development of low pressure
offshore.

There will be a temperature dichotomy across the country Sunday
into the early part of next week with the amplified upper level
pattern in place. It will be quite chilly for this time of year
across much of the Intermountain West and the northern Rockies,
with highs 10-20 degrees below mid-May climatology. This also holds
true across much of Arizona as well, followed by a moderation
trend by Tuesday as the upper low moves out. In contrast, it will
continue to be quite hot across southern Texas with Heat Risk in
the major category most days, and it will also be hot and humid for
much of the Deep South and into Florida with highs reaching 90-95
degrees and plenty of humidity.

Santorelli/Hamrick


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Fri May 16 2025

Valid 12Z Mon May 19 2025 - 12Z Fri May 23 2025

...Severe weather and flash flooding forecast for parts of the
central U.S. Monday-Tuesday...

...Hazardous and record heat could continue especially across Texas
and Florida into mid-next week...


...Overview...

The primary weather feature next week will be an upper trough/low
over the Rockies Monday that tracks east as the week progresses
along with its associated surface low pressure/frontal system. This
pattern will provide ample lift and instability for rain and
thunderstorms in the Plains, Mississippi Valley, and Ohio Valley
early week and spreading into the East for midweek and beyond.
Meanwhile a subtropical upper ridge will continue to cause hot
conditions to areas of the Southeast, particularly into southern
Texas and Florida, where the heat could be hazardous and/or record
setting.


...Guidance/Predictability Assessment...

Model guidance begins the medium range period Monday in reasonably
good agreement with the primary upper trough and embedded upper
low(s) in the Interior West and spinning up a surface low in the
central Plains. Models diverge rather quickly with the evolution of
the ejection of embedded upper-level energies and subsequent
details at the surface. A second upper-level shortwave looks to
lead to secondary low development over the central/southern Plains
Tuesday south of the initial surface low development. The 00Z
ECMWF/UKMET and 00/06Z GFS maintain the more northern low before a
complex evolution that generally tends to favor the southerly low
becoming the main low as the system progresses northeastward into
the Midwest/Ohio Valley by mid-next week. The evolution of the
surface low pattern in the 06Z GFS is a bit more similar to the 00Z
ECMWF compared to the 00Z run initially in feature
location/progression. The 06Z then shows a much faster progression
of leading energy eastward out of the Ohio Valley and into the Mid-
Atlantic/Northeast while the 00Z GFS remains more similar to the
00Z ECMWF with a slower progression. The progression of the low(s)
is also faster in the deterministic guidance compared to the
ECENS/GEFS means, which is also faster compared to the prior
guidance as well as WPC forecast. The 00Z CMC is more aggressive in
having the southerly low become the solo, primary low quickly in
the subsequent evolution of the pattern with a much slower and
southerly track. Another complex evolution looks to occur heading
into later next week as the upper-trough merges with northern
stream energy, and a coastal low develops off the coast of the Mid-
Atlantic, lifting northeastward in parallel with the coast. Both
the 00Z GFS/ECMWF and the respective means are in generally good
agreement despite typical location/timing differences with
increasing lead time. The 06Z GFS remains much faster, bringing the
coastal low well offshore compared to the other guidance,
suggesting a higher level of uncertainty despite the good
agreement. The updated WPC forecast begins with a blend of the 00Z
ECMWF/UKMET and 00/06Z GFS given the transition between the 06Z to
00Z with respect to better agreement with the other guidance. The
00Z CMC was not included because of the outlier nature of the
southerly system track. A contribution from the ensemble means is
added for the mid- to late period given the loss of the time-
limited UKMET, removal of the 06Z GFS given a diverging solution,
and general increase in uncertainty. The blend results in a
forecast that maintains generally good continuity with the prior
WPC forecast, with the greatest differences being a faster
progression of the system eastward through the Ohio Valley and a
stronger coastal low towards the end of the period.

...Weather/Hazards Highlights...

The notable surface low pressure system consolidated over the
central Plains by Monday will draw in above average moisture (with
precipitable water values around the 90th percentile for this time
of year) and ample instability ahead of its associated cold front.
The upper low spinning aloft will provide good dynamical lift, and
this combination of ingredients will lead to widespread rain and
thunderstorms and mesoscale convective systems, with best chances
slowly progressing east from the central to east-central to eastern
U.S. as next week progresses. The greatest chances for heavy rain
causing flash flooding look to be across the Mid-Mississippi and
western Ohio Valleys Monday, and a more expansive area from the
Mid- Mississippi east through the Ohio Valley and into the central
Appalachians Tuesday, as moisture and instability pool near a warm
front stretching west-east that could promote training storms. Thus
Slight Risks are in place for the Day 4/Monday and Day 5/Tuesday
ERO over pretty similar areas before the upper/surface lows eject
eastward. Broad Marginal Risks surround the Slights to the south
and east where convection may be more scattered, and on Monday a
Marginal curls back west closer to the low track. Severe weather is
also possible per the Storm Prediction Center, as they delineate a
severe area on Monday for the south-central Plains to Missouri
Valley Monday, with the greatest threat over eastern Oklahoma, and
another area for the Lower/Middle Mississippi Valley on Tuesday.
Rain and thunderstorm potential should press toward the Eastern
Seaboard by mid to late week with moderate to locally heavy
rainfall possible for the Mid-Atlantic Wednesday into coastal New
England Thursday.

Some precipitation is forecast in the Intermountain West under the
upper trough/low for the first half of next week. The cool
temperatures aloft could lead to May snow in higher elevations of
the Rockies particularly Monday. Convective showers are possible
near the Four Corners region. Meanwhile rounds of modest
precipitation may be possible in the Northwest. Light rain may
linger in the Northeast early next week under the influence of a
northern trough.

Warm to hot temperatures are likely across the southeastern U.S.
as the subtropical upper ridge reaches the region. Southern Texas
in particular will remain hot, with temperatures well into the 100s
leading to Major to Extreme HeatRisk through Tuesday. The Florida
Peninsula should see warm temperatures in the mid to upper 90s.
Both areas could see record or near record warm lows and highs.
Meanwhile the trough aloft will promote below normal temperatures,
especially for highs, across the Interior West Monday and into the
northern Plains Tuesday. Below average highs by around 10 degrees
are also possible in the northern tier. As the trough tracks east,
cooler than average temperatures should shift into the eastern
third of the country under it. This may also moderate the
temperatures somewhat in the South. But upper ridging poking into
the West will raise temperatures to above normal there by later
week, bringing highs well into the 100s for the Desert Southwest.

Putnam/Tate


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
317 PM EDT Sat May 17 2025

Valid 12Z Tue May 20 2025 - 12Z Sat May 24 2025

...Severe weather and flash flooding forecast for parts of the
Mississippi and Ohio Valleys Tuesday...


...Overview...

A slow moving upper low over the central U.S. Tuesday shifts east
and strengthens over the Great Lakes Wednesday and the Northeast on
Friday before lingering over Atlantic Canada next weekend.
Meanwhile, subtropical ridging over the Southeast becomes more
suppressed from the eastern low/troughing by midweek. Finally,
general ridging over the west will lead to warmer than average
conditions across California and the Great Basin/Desert Southwest
midweek, expanding across the Four Corners and southern High
Plains late in the week.


...Guidance/Predictability Assessment...

12Z global guidance has improved agreement with the upper low
closing off Tuesday evening over the central Plains, a new and
deeper low development over the Great Lakes on Wednesday, a more
southerly track of the low over the eastern Great Lakes Thursday
and the departure of the low from the Northeast Friday into
Saturday. The GFS remains the most progressive solution as it opens
the low on Thursday while the EC/CMC keep it closed. One of the
more notable shifts with 12Z guidance is QPF on Wednesday focused
farther south over the Mid-Atlantic and central Appalachians
compared to prior runs.

Upstream, consensus on broad ridging over the Southwest midweek
that shifts east to the southern Plains by Friday. The 00Z EC was
the least with the next trough into the PacNW on Friday, but the
12Z consensus is now for a trough or low to reach Washington on
Friday.

The WPC forecast was based on a blend of mainly deterministic
models for Days 3-5 with ECENS/GEFS ensemble mean inclusion for
Days 6-7 as spread increased.


...Weather/Hazards Highlights...

Ample moisture and instability over the Miss/OH valleys Tuesday
ahead of a deep low over the east-central Plains along with strong
dynamical lift aloft will lead to widespread rain and
thunderstorms and mesoscale convective systems into Tuesday night.
This covers a broad area including most of the TN/OH Valleys and
back across the Midwest through southern MN where a broad Day 4
Slight Risk ERO remains with only minor edits to the shape. The
severe
weather threat area is focused over the southern portions of this
precip area in the warm sector over the TN Valley per the Storm
Prediction Center Day 4 Convective Outlook.

Rain and thunderstorm potential shifts east over the Appalachians
Wednesday as the low tracks east. Locally heavy rainfall is
possible particularly for the Mid- Atlantic region on Wednesday
where a Day 5 Marginal ERO remains. There is better agreement on
the Day 5 precip area today, but the overall magnitude seems to be
the greatest reason to not upgrade to a Slight Risk at time. Rain
chances will make their way into the Northeast Thursday-Friday as
the surface low pivots northward.

Elsewhere, some weak troughing aloft and frontal systems tracking
through the Northwest next week could produce rounds of modest
precipitation there. Most precipitation should be rain aside from
the highest peaks. Some rain may eject into the northern High
Plains by Thursday, with possibly another round of storms emerging
in the central U.S. by Friday, but with quite a bit of uncertainty.

Heat lingers over south Texas and the Florida Panhandle through
Tuesday, but the suppressed ridge should bring some temperature
relief by Wednesday. The trough/low aloft will promote below
normal temperatures across the northern tier with 10 to 15 degree
below normal temperatures working east mid to late week.
Upper ridging over southwestern U.S. will raise temperatures to
above normal there by Wednesday, expanding east across the Four
Corners states by Thursday and into the southern Plains late in
the
week. Highs will be well into the 100s in the Desert Southwest with
temperatures nearing 100 again in parts of Texas eventually.


Jackson


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw