Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/02/24

Area Forecast Discussion

National Weather Service Burlington VT

 928 PM EST Thu Feb 1 2024

.SYNOPSIS...
Cloudy conditions will prevail across Vermont and northern New York
this evening and tonight with a prevailing moist flow from the
eastern Great Lakes. An upper-level low over southwestern Quebec
will move southeastward overnight, bringing periods of light snow
shower activity. Any snow accumulation will be light. Skies will
remain cloudy throughout Friday, but high pressure building in from
the northwest will bring some long-awaited sunshine during Saturday.
Generally dry, quiet weather with seasonable temperatures is
expected across our region for next week.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 923 PM EST Thursday...Areal coverage of precip is waning
behind initial s/w as better forcing is lifting into southern
Canada and some mid lvl drying is occurring. Have tweaked pops
to reflect the highest values acrs the northern Dacks into the
northern Greens, while not much occurs in central/southern VT
this evening. Sfc analysis places wind shift associated with
cool frnt approaching the SLV and should be acrs northern NY
btwn 04z-08z, CPV btwn 08z-12z and thru VT by 15z. It should be
noted caa lags boundary by several hours per latest obs, but
expect another round of light precip associated with fropa,
followed by a period of upslope snow showers on Friday morning.
As winds shift to the north/northwest and blocked flow develops,
anticipate quickly lowering cigs here in the CPV with some light
precip possible around the morning commute. Temps wl be hovering
near freezing, so a few slick spots are possible. Did bump hrly
temps up several degrees thru early morning, per latest
obs/trends. Rest of fcst in good shape.

Previous discussion below:
Prevailing stratus deck remains locked in place across our
region, reinforced by a moist WSWLY flow from Lake Ontario and
Lake Erie. Continue to see intervals of drizzle and light snow,
especially in west-facing upslope areas of the Northern
Adirondacks and Green Mountains. The HRRR and NAM-3km model
soundings continue to indicate the saturated layer extends up to
-5C to -10C through early this evening, which is marginal for
the generation of cloud ice. Have maintained mention of light
drizzle and snow showers next several hours, with localized
freezing drizzle above 1500ft. The microphysical regime changes
overnight as compact closed low north of the Ottawa Valley
translates southeastward toward the intl border. This system
will bring deeper/colder saturation and better potential for
snow showers overnight, especially across northern areas. All in
all, not expecting any significant travel impacts with a
dusting to 1" of snow in most areas, and 1-3" for the summits of
the northern Greens and Adirondacks. Indicated a period of
likely PoPs (60-70%) late this evening across the mountains.
Will see S-SW winds gradually shift north as trough axis passes
by after midnight. Only modest CAA expected late, and with low
overcast in place, not expecting any significant drop in
temperatures. Will see lows generally 28-32F overnight, and
locally just above freezing near the shores of Lake Champlain.

Northerly low-level flow continues on Friday with an inversion layer
around 2000ft. Should see some morning snow showers, trending toward
very light drizzle/freezing drizzle as mid-level drying occurs
during the day. Little or no snow/ice accumulation is expected
during Friday. Highs generally 30-35F and locally in the upper 30s
for highs in the valleys of s-central VT.

High pressure building southeastward from Ontario brings potential
for some BINOVC during friday night. Any breaks will help with
radiative cooling. Have stayed a couple degrees above the MOS
consensus with overnight lows mainly in the upper teens to lower
20s. Could be some locally colder readings in the nrn Adirondacks
and far nern VT if clouds decrease in coverage earlier than
presently anticipated.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 306 PM EST Thursday...Very quiet weather is expected for the
weekend as surface high pressure builds over the region. Aloft,
we`ll be on the western periphery of a mid/upper level trough over
the New England coastal waters which will provide periods of
mid/high clouds, but everyone should finally see the sun, even
though it may be between clouds across northern zones. Winds will be
relatively light from the north at 5-10 mph, and temps slightly
above normal with highs in the mid/upper 20s to low/mid 30s, and
lows in the teens to low 20s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 306 PM EST Thursday...Next week continues to look quiet as
well, with very little chance for precipitation. Through Tuesday,
we`ll remain on the western edge of the aforementioned mid/upper
trough, and a weak backdoor cold front will drop from NE to SW on
Monday supporting a very slight chance of snow across eastern zones.
Finally by late Wednesday into Thursday the trough shifts eastward
enough to allow upper level ridging to build in with clearer skies
(hopefully) developing. Temps remain near to slightly above normal
through the period.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Through 00Z Saturday...Mostly VFR conditions prevailing at our
taf sites with MVFR at SLK/EFK and IFR only at MSS. Precip on
radar has produced a mix of rain/snow with vis mostly in the
MVFR range. CIGS with the southwest/westerly 925mb to 850mb flow
have been mostly VFR in the CPV taf sites with intervals of
MVFR/VFR at MPV and MVFR/IFR at SLK. Have utilized a prevailing
fcst thru 06z with highest confidence of IFR CIGS at MSS.
Otherwise, based on obs over the past 1 to 2 hours, thinking
intervals of IFR CIGS/VIS at SLK/EFK, especially in the heavier
precip. As a cold front drops south acrs our taf sites after
06z, winds shift to the north/northwest and anticipated CIGS
quickly becoming IFR at BTV/EFK/RUT/MPV and SLK for several
hours on Friday morning, while improving at MSS with drier air
moving into that TAF site on northwest winds. Conditions wl
slowly improve to mostly MVFR by 16z, with lingering IFR
possible at mtn terminals. Summits will remain obscured in
clouds thru the period.

Outlook...

Friday Night: Mainly VFR, with local MVFR possible. Slight chance
FZDZ.
Saturday: VFR. NO SIG WX.
Saturday Night: VFR. NO SIG WX.
Sunday: VFR. NO SIG WX.
Sunday Night: VFR. NO SIG WX.
Monday: Mainly VFR, with local MVFR possible. NO SIG WX.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. NO SIG WX.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Banacos
NEAR TERM...Banacos/Taber
SHORT TERM...Lahiff
LONG TERM...Lahiff
AVIATION...Taber



Area Forecast Discussion

National Weather Service Hastings NE

 544 PM CST Thu Feb 1 2024

.KEY MESSAGES...

- Areas of fog likely tonight, with a 60 to 90 percent chance of
  becoming dense for at least N and W portions of the area.

- The next chance for rain arrives Friday night, with most of
  the rain falling on Saturday and Sunday.

- Rain amounts will vary widely across the area, with 60-90%
  chance for at least 1" mainly S/W of the Tri-Cities, as
  opposed to a 40-60% chance of 0.5", or less, closer to
  Columbus, NE area.

- Above normal temperatures remain likely through the end of
  next week.

&&

.DISCUSSION...
Issued at 420 PM CST Thu Feb 1 2024

Tonight - Friday AM:
Areas of dense fog have persisted across portions of north
central and northeast Neb. today, and short term hi-res guidance
has remained fairly consistent that this area will only expand S
and W with time this evening. This will be supported by NErly
low level flow to the N of a sfc low and inverted trough
currently located from around Alma to Omaha. Thus, the backed
low level flow will also have an upslope component to aid in fog
formation. Have joined neighboring offices and issued a Dense
Fog Advisory where confidence is currently highest for
widespread visibilities around 1/2 mile, or less. Some expansion
of the advisory NE along the Platte River, and S along Hwy 281,
is possible, but confidence is lower for these locations as they
remain closer to warmer Srly flow and keep wider T/Td spreads.
HREF probabilities and HRRR visibility progs are less suggestive
of dense fog in these areas. Fog should lift and scatter towards
midday on Friday.

Weekend Rain:
Overall, no significant changes in latest thinking regarding the
upcoming rain chances. Heaviest rain axis continues to focus
over the SW half of the forecast area, just W/S of the Tri-
cities, where latest probabilities for at least an inch of
precipitation are around 60-90%. Within the max forecast swath,
the 25th percentile in these areas is generally above 0.75",
which should be a floor for expectations. However, think it is
worth leaning towards the high end of the curve with this system
given ECMWF progs of atmospheric moisture levels 200-300%+
relative to normal for early Feb. The 75th percentile ramps up
to around 1.5", and the 90th percentile is up to 1.75", which
could come to fruition if there are indeed some convective
elements/thunder to the rain this weekend. Just so happens that
the latest deterministic EC is near these upper end amounts,
mainly in north central KS. One might think this should lead to
widespread flooding given its only early Feb, but there are
several factors working against significant issues. 1) the rain
is somewhat long and drawn out, roughly 36 hours from start to
finish, with rates most of the time outside of convective
elements only around 0.10"/hr. 2) office observations suggest at
least 5" of top soil thaw, which is probably conservative
relative to areas in the max QPF band as they have been warmer
and had less snow to melt. 3) related to the previous bullet,
these areas had less snow pack and thus less snow to liquid
equivalent that has melted over the past week 4) most of the
forecast area remains in some level of drought classification,
and area streams are currently at or below normal streamflow.
The rain will, however, likely lead to ice breakup and flow
downstream, so areas along the Platte and Loup basins will have
increasing risk of ice jams this weekend.

Rain amounts are forecast to taper off fairly quickly NE of the
Tri-Cities, which is the area with highest lingering snow cover,
and had the highest snow depth coming into this warm spell. This
is also good news for the flooding threat. In fact, there`s a
40-60% chance that total rain amounts will remain under a half
inch for areas like Central City towards Columbus. The wild card
to the entire rain amount forecast is potential for convective
rain rates, at times, over the weekend and will need to be
monitored. The primary time frame for most of the rain
accumulation will be Friday night through Sunday morning, with
rain expected to taper off Sunday aftn or early evening. Could
see some drizzle as early as Friday afternoon, but anything more
than that should hold off until after sunset.

Dry conditions return on Monday, and above normal temperatures
continue as upper level ridging returns. A upper trough moves in
from the west by the middle of the week. Strong southerly flow ahead
of this system may push temperatures to near 60 degrees in some
locations on Wednesday. Chances for rain then arrive Wednesday into
next Thursday. After this system departs, global ensembles favor a
cooling trend next weekend...but probably still near to above
normal. Long-range guidance hints at another shot of more "winter-
like" temperatures arriving in mid-February.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 529 PM CST Thu Feb 1 2024

Both TAF sites are currently experiencing VFR conditions. Fog is
expected to develop overnight, however the exact timing of
development is still unclear. Model guidance has been trending
the start time later over the past few hours. Most models show
development between 05Z and 08Z. The 22Z HRRR has initialized
the fog in northern NE quite well. Guidance from this run of the
HRRR shows lower visibilities reaching both terminals around
06Z. A sharp gradient in lower visibilities is expected to
develop right around Grand Island. Two scenarios look possible
for KGRI. 1.) KGRI could see a brief drop in visibilities before
easterly winds push the edge of the fog further west resulting
in VFR conditions or 2.) the fog could remain in place over KGRI
through the night resulting in low visibilities and IFR
conditions. Once fog develops at KEAR it will remain in place
until the mid-morning.

&&

.CLIMATE...
Issued at 610 PM CST Wed Jan 31 2024

Several daily records for mainly warm low/minimum temperature
and MAYBE one daily precipitation record are possible at Grand
Island/Hastings airports in the upcoming days (the two sites for
which we issue official Record Event Reports...RERGRI/RERHSI).

Please keep in mind that for record warm lows to become OFFICIAL
they need to "survive" the entire midnight-to-midnight CST
calendar day. Possible records that appear most threatened follow:

- Grand Island airport (GRI) possible warmest low temp records:
Feb. 3 (Sat): forecast 44...current record 37 in 1909
Feb. 4 (Sun): forecast 38 at midnight...current record 36 in 1927
Feb. 5 (Mon): forecast 32...current record 35 in 2005


- Hastings airport (HSI) possible warmest low temp records:
Feb. 2 (Fri): forecast 38...current record 36 in 1934
Feb. 3 (Sat): forecast 46 at midnight...current record 37 in 1962
Feb. 4 (Sun): forecast 38 at midnight...current record 36 in 1991/1954
Feb. 5 (Mon): forecast 33...current record 35 in 2005/1954

- Hastings airport (HSI) possible daily precipitation record:
Feb. 3 (Sat): forecast 0.71"...current record 0.78" in 2012

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Dense Fog Advisory from midnight tonight to noon CST Friday
     for NEZ039-040-046-060-061-072-073-082-083.
KS...Dense Fog Advisory from midnight tonight to noon CST Friday
     for KSZ005-017.

&&

$$

DISCUSSION...Thies
AVIATION...Mangels/Carothers
CLIMATE...Pfannkuch/Thies



Area Forecast Discussion

National Weather Service Louisville KY

 937 PM EST Thu Feb 1 2024

.Forecast Update...
Issued at 935 PM EST Thu Feb 1 2024

The afternoon forecast package remains largely on track with small
tweaks to temperatures and dew points to account for latest trends.
Current surface analysis locates the weak cold front approximately
over central Indiana with associated broken strato cu layer noted in
the nighttime microphysics GOES RGB product. RAP forecast soundings
continue advertising a very shallow cloud layer which might not even
support drizzle. Therefore, continue indicating a dry frontal
passage around sunrise with increasing sky cover and no
precipitation. Winds, on the other hand, will become light and
variable as the front approaches and veer to the north behind the
actual front, inducing weak cold air advection. Finally, clouds will
begin to scatter out in the afternoon as the thermal trough, and
coldest 850-mb temps, stay well to east-northeast.

&&

.Short Term...(Tonight through Friday evening)
Issued at 305 PM EST Thu Feb 1 2024

Dry, pleasant weather continues into Friday with increasing cloud
cover tonight into Friday.

An upper level shortwave trough is positioned over the Great Lakes
this afternoon and is forecast to rotate southeast over the Ohio
Valley tonight. SCT thin cirrus has begun to overspread the region
this afternoon, and high clouds will continue to spread in from the
north and west this evening into tonight. A sfc cold front currently
draped west through Chicago will drop south through southern IN and
central KY between roughly 06-16z Friday morning, resulting in a
wind shift and modest CAA. The weather will remain dry, with very
little available moisture above 850 mb. Temps will be on the warm
side of normal with lows in the mid 30s to around 40 degrees.

In terms of sensible weather, the main impact will likely be a layer
of low stratus building in from the north in the wake of the cold
front. Expect a much cloudier Friday, with clouds scattering out
from north to south Friday afternoon and evening. Afternoon highs
will be slightly cooler than today given the increased cloud cover.
Temperatures likely won`t make it out of the upper 40s in the
Bluegrass, with mid 50s in south-central Kentucky.

&&

.Long Term...(After midnight Friday night through Thursday)
Issued at 300 PM EST Thu Feb 1 2024

==================================================================
Key Messages:

* Chance of some light rain showers late this weekend along the
  KY/TN border.

* Generally mild conditions otherwise through the long term period.
==================================================================

Friday Night through Sunday Night...

Upper level pattern will be highly amplified at the beginning of the
period with a sharp ridge along the MS River with troughing over the
western CONUS.  The upper troughing over the western CONUS will end
up closing off into an upper level low which will then roll eastward
through the southern Plains and into southeast states through the
weekend thanks to a strong upper level jet within the southern
stream.  The model trends with this system continue to show it
passing further south of the region with each run.  So current
thinking is that the best chances of any rain will be in far
southern KY late Sunday and early Monday.

Otherwise, the weekend for much of the region will be dry with mild
temperatures.  Lows Friday night will be in the upper 20s to the
lower 30s.  Saturday`s highs will feature a gradient with upper 40s
to around 50 across SE IN and the Bluegrass region of Kentucky.
Across central (I-65) and southern KY, highs in the low-mid 50s are
expected.  Lows Saturday night will drop back into the low-mid 30s
with highs on Sunday warming back into the middle 50s.  Lows Sunday
night will be in the mid 30s.

Monday through Thursday...

With the closed upper low rotating through the southeast and off the
southeast coast, an upper level cut off ridge will gradually build
over the Midwest and then expand east/northeast through the week.
This happens in response to larger height falls occurring over the
western CONUS as the next big trough axis moves ashore.  With
ridging aloft and high pressure at the surface, mostly sunny days
and mostly clear nights are expected from Monday through Wednesday.
We`ll likely see a bit more cloudiness move in Thursday as the
western CONUS trough moves into the Plains.

Highs Monday through Wednesday will feature readings in the low-mid
50s with overnight lows in the upper 20s/lower 30s.  Highs by
Thursday will be in the upper 50s and probably pushing to near 60 in
a few areas.

&&

.Aviation...(00Z TAF Issuance)
Issued at 631 PM EST Thu Feb 1 2024

Impacts/Confidence:
- High confidence in MVFR ceilings late tonight.
- High confidence in veering winds between 2/9-14Z
- Low to medium confidence in lifting ceilings tomorrow.

Discussion...VFR conditions will prevail this evening and first half
of the overnight hours. However, a cold front currently analyzed
over the Great Lakes will continue sagging southward and move
through the TAF sites late tonight and during sunrise. Most notable
changes will be a wind shift to the north and MVFR stratus layer in
the wake of the front. There is a low chance for a brief period of
IFR ceilings at HNB and LEX after 12Z, but confidence was not
sufficient to include it in the TAF. Otherwise, guidance hints at
improving conditions after 18Z; however, models are always overly
optimistic in such low stratus events so decided to maintain MVFR
through the end of the forecast pending new updates.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...None.
&&

$$

Update...ALL
Short Term...EBW
Long Term...MJ
Aviation...ALL



Area Forecast Discussion...Updated

National Weather Service Saint Louis MO

 902 PM CST Thu Feb 1 2024

.UPDATE...
Issued at 901 PM CST Thu Feb 1 2024

A narrow band of very light rain and sprinkles associated with an
area of mid-level convergence and saturation is currently stretching
from portions of central Missouri into southwestern Illinois. Rain
within this band has had greater success reaching the surface
than previously expected per recent surface obs. Therefore, we`ve
increased the mention of rain in our forecast above sprinkles to a
low chance (30%) for light rain across that portion of the CWA.
This band`s presentation on radar is likely still overselling what
is reaching the surface given the wedge of dry air present from
about 700mb to the surface seen in RAP analysis and ACARS
soundings out of KSTL. Guidance indicates that the mid-level
convergence will weaken quickly after midnight, bringing an end to
the rain chances shortly thereafter.

Elmore

&&

.KEY MESSAGES...

Key Messages:

- A cold front moving through tonight will cool us down for the
  weekend, though temperatures will remain well above average.

- There is still a potential (40-50%) for rain this weekend
  focused mainly from central through southeast Missouri. Amounts
  will likely remain under half an inch.

- Next week will start off "cooler" (40s and 50s) and gradually
  warm ahead of another chance for rain (40-50%) late next week.


&&

.SHORT TERM...  (Through Late Friday Night)
Issued at 230 PM CST Thu Feb 1 2024

Despite the cloud cover, temperatures areawide have quickly climbed,
with some locations in southern Missouri having reached 70 degrees
by noon. For areas that do see 70, enjoy it while it`s here. Tonight`s
cold front is pushing its way south, having passed through Des
Moines, IA and Chicago, IL early this afternoon. It is expected to
enter northeast Missouri by this evening, switching winds from
southwesterly to easterly, and kicking off a modest cooling trend.
Patchy advection fog is possible behind the front overnight,
particularly in areas north of I-70. At the time of writing,
slightly elevated winds and warm ground temperatures are expected
to keep widespread, dense fog at bay.

Low cloud cover behind the cold front will last into Friday,
disallowing most of the region to warm as much as we`ve seen
today. Highs in the low 50s are forecast for portions of northeast
Missouri through southwest Illinois where cloud cover will be
thickest, and highs may climb into the low 60s in central and
southeast Missouri where skies will be clearer.

Jaja

&&

.LONG TERM...  (Saturday through Next Thursday)
Issued at 230 PM CST Thu Feb 1 2024

Highly amplified upper level ridging in the central CONUS will slide
east on Friday, eventually being undercut by a deepening upper low
Saturday into Sunday. This low will close off and move through the
Southeast CONUS, drawing ample Gulf moisture to the north as it
travels. This setup will spur the formation of a surface low
pressure system in the southern Plains and widespread rainfall
spanning from the northern Plains to the Gulf of Mexico. The
question over the past several days has been if we`ll see any of
this rain, and the answer has (slowly) become more clear.

Deterministic guidance has begun to converge toward a common
solution for the weekend rain potential. The aforementioned rain
corridor is expected to approach the Missouri from the southwest
before brushing our southwest border (Moniteau through Reynolds
County, MO), pivoting to the south, and exiting the area. The
probability of precipitation in these areas remains similar to
previous forecasts, 40-50%, which is similar to the amount of
ensemble members that depict rain at KFAM. Areas that see rain this
weekend aren`t likely to see substantial amounts, as ensemble
probabilities of greater than half an inch peak in Reynolds County
at 20-50%.

Despite this weekend`s system cooling the region down, there`s still
very high confidence that we`ll remain above average through next
week. Sunday will kick off next week with highs in the 40s and 50s.
Ridging aloft and surface high pressure will allow us to gradually
warm through the early week unimpeded by excessive cloud cover or
precipitation. After the benign early week, there is growing
confidence that system will bring the potential for rain back to the
Mid-Mississippi Valley late next week into next weekend.

Jaja

&&

.AVIATION...  (For the 00z TAFs through 00z Friday Evening)
Issued at 519 PM CST Thu Feb 1 2024

A weak cold front will move southward through the region and over
the local terminals overnight, causing winds to become
northeasterly in its wake. Along and behind this front, an area of
low stratus is expected to develop and slowly spread across the
terminals late tonight and early tomorrow morning. Given the dry
air in place across the region currently, I suspect that weather
models may be too pessimistic on the height of this stratus, and
have kept flight conditions MVFR for now. However, I can`t rule
out that ceilings briefly drop to IFR for some local terminals.
Additionally, this dry air does not build confidence in fog
developing as some weather models suggest, so I`ve kept it out of
most TAFs for tonight as of now. The exception is KUIN, where if
fog does develop across the region, it would most likely be around
that terminal. Otherwise, the passage of the front will be dry,
though some local terminals may experience a brief sprinkle this
evening ahead of the front. Conditions are expected to improve
tomorrow morning as any fog that develops dissipates and stratus
lifts.

Elmore

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

$$

WFO LSX



Area Forecast Discussion

National Weather Service Twin Cities/Chanhassen MN

 617 PM CST Thu Feb 1 2024

.KEY MESSAGES...

- Above normal temperatures continue through next week.

- Next chance for precipitation holds off until late next week.

&&

.DISCUSSION...
Issued at 225 PM CST Thu Feb 1 2024

A few high clouds have started to move southwest across the area
this afternoon, showing up quite well on the Day Cloud Type RGB
satellite imagery showing up in red compared to the ground which
is colored blue. We can see our lack of snow cover within the
RGB as the greens indicating snow cover are confined to central
to southeast South Dakota and portions of southern Wisconsin.
With a lack of significant weather systems within the scope of
the forecast, we are looking at a relatively quiet period where
what little snow pack exists will continue to erode.
Temperatures as of 2pm have reached 50 in the Twin Cities and
mid to upper 40s for the rest of the area, which is still 20 to
25 degrees above normal high temperatures in the mid 20s for
this time of year. We will maintain some of the warmth overnight
as we will see more cloud cover return in the form of lower
stratus clouds, with a chance for fog once again although less
dense and widespread than the last few nights. The best chance
to see some dense fog would be the southwestern portions of the
state south and west of the Minnesota River and along I-90, with
reduced coverage elsewhere. The big difference is due to much
lower dew points today compared to yesterday, due to greater
mixing and a shift in wind direction. Temperatures will need to
fall an additional 5-10 degrees more than last night in order
for fog to begin to form, and with lower clouds more likely this
would also inhibit the spread.

The weather remains quiet through the weekend and into next week
with a lack of significant weather systems. Broad surface high
pressure and ridging centered over the Great Lakes will keep our
upper level flow out of the south with continued warm air returns
keeping us in the mid to upper 40s through much of the period, even
approaching another day in the mid 50s by next week Thursday. Long
range guidance has continued to shift what looks to be our next
chance for sensible weather aside from fog in the form of a larger
system towards the end of next week, the location and timing all
differing compared to yesterday. What this means is we still have a
while to wait before we can talk about any sort of precipitation,
and even the temperature change alluded to within guidance is also a
question depending on where, when, and how strong the potential
system ends up being. For now, our strong warmer than normal pattern
will continue, and it will not be until at least the middle of the
month until we moderate back towards what is typical for February.
One thing of note as we head throughout the month is we gain about 1
degree on our average high/low temperatures every 2 days. Mid 20
normal highs and single digits lows for normals to start the month
increase to mid 30s and mid teens by the end. So even if the 3-4
week signal is for near normal temperatures, this still indicates
more upper 20s to low 30s than any kind of stronger cold.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 615 PM CST Thu Feb 1 2024

VFR with SCT to potentially IFR cigs early tomorrow
morning. As mentioned in the previous discussion, we are continuing
to monitor low stratus that is making its way southwestward as part
of a back door cold front that will push through overnight. Hi-Res
guidance such as the HRRR and RAP both appear to be very aggressive
with this low stratus coverage across all sites. However, based of
of observations, continuing with the previous TAF thinking by using
prevailing low sct cigs through much of tonight. Early tomorrow
morning, MN sites could see a brief period of low MVFR/IFR cigs
before scattering out by mid-morning. Easterly winds becoming
Southeasterly by tomorrow afternoon, with a few gusts nearing 18kts
at AXN and RWF.

KMSP...VFR with MVFR cig potential early tomorrow morning. Low
stratus continues to make its way southwestward towards MSP
overnight. Confidence remains low on how much of this stratus
will impact the terminal this period. Did not feel confident
with how aggressive the HRRR and RAP treated these cigs
therefore decided to introduce only bkn MVFR cigs briefly
Friday morning before scattering out. Easterly winds becoming
Southeasterly by tomorrow afternoon.

/OUTLOOK FOR KMSP/
SAT...VFR, slgt chc MVFR. Wind SE 10-15 kts.
SUN...VFR. Wind E 5-10 kts.
MON...VFR. Wind N 5-10 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.

&&

$$

DISCUSSION...TDH
AVIATION...RMD



Area Forecast Discussion

National Weather Service Phoenix AZ

 513 PM MST Thu Feb 1 2024

.UPDATE...Updated 00Z Aviation Discussion.

&&

.SYNOPSIS...
A cold front will sweep through the region tonight bringing light
to moderate rainfall across the entire area. Below normal high
temperatures are then expected for Friday through the weekend with
lingering shower activity over the Arizona high terrain lasting
into Saturday. After a brief period of drier conditions later this
weekend into Monday, yet another weather system is expected to
bring a prolonged period of occasional rainfall to the region
during the latter half of next week.

&&

.DISCUSSION...
Temperatures across Arizona continue to run as much as 5 to 10
degrees above normal, particularly from Phoenix eastward, while
further west, temperatures have already dropped into the upper 50s
across the Imperial Valley in southeastern California. Meanwhile,
dewpoints are running several degrees higher than at this time
yesterday and this portends a continued moistening trend and an
increased threat of precipitation.

Latest water vapor imagery reveals a potent atmospheric river
moving eastward through southern California. IVTs continue to
decrease, nevertheless a widespread rain event is still
anticipated across the region. Meanwhile, shower activity
continues to blossom across Imperial and eastern Riverside
Counties early this afternoon, which is generally in sync with
what was depicted in the 12z HREF.

CAMs indicate the rain will continue to expand in coverage late
this afternoon across southwestern Arizona before moving into the
Phoenix area this evening. Model consensus also indicates
precipitation will expand in coverage and intensify overnight
across the Valley as jet-forced ascent combines with surface-based
lift along the eastward propagating cold front. Although
instability will generally be weak, upper quartile CAMs do
indicate SBCAPEs of 150+ J/kg, which may result in localized
convective linear elements, isolated thunder, and enhanced
rainfall rates, particularly along the front. After midnight,
rainfall will generally taper off across central Arizona before
moving into the higher terrain east of Phoenix.

During the early morning, the upper trough and associated cold
pool aloft will also promote additional weak instability, however
there is some uncertainty as to exactly when this will occur. For
instance, the HRRR suggests scattered shower activity will
redevelop as early as mid-morning across central Arizona, while
other CAMs indicate this will be delayed until the afternoon as
some of the instability is negated by general subsidence behind
the trough axis. Any cells that develop will have the potential to
produce isolated lightning and small hail. At the surface,
conditions will also be considerably cooler than they have been
with high temperatures generally in the lower 60s.

Expected storm total rainfall has changed very little over the
past 24 hours and ranges from two tenths to one third of an inch
across southwestern Arizona and southeastern California. Across
south-central Arizona, a half of an inch to three quarters of an
inch is anticipated in the Phoenix area, while upwards of an inch
is expected in the higher terrain north and east of Phoenix though
the latest NBM also indicates the largest amount of uncertainty
in these areas. Snow levels also remain too high for any
measurable snow, except across eastern Gila County above 6000 feet
in elevation.

&&

.PREVIOUS DISCUSSION...
For this weekend, the Desert Southwest will fall in between weather
systems as weak ridging develops over the region and leads to
gradual warming for Sunday and Monday. Forecast temperatures remain
below normal this weekend with highs still struggling to top 65
degrees, but by Monday much of the lower deserts will see readings
topping out around 70 degrees.

After a couple days of drier weather, the next round of unsettled
weather looks to take shape by Tuesday as a trough develops over
the eastern Pacific just to our west. The large scale synoptic
setup is also expected to create a blocking ridge over the center
part of the country which will in turn keep the troughing and
active weather over the Southwestern U.S. for several days next
week. For now, model ensembles heavily favor the first shortwave
trough and a modest atmospheric river reaching the Desert
Southwest at some point on Tuesday with good rain chances from
that point through Wednesday. This active period should then
persist through at least next Friday and maybe even into next
weekend as guidance shows the trough nearly stationary just to
our west or directly over our region. Given it is 5-8 days away,
there remains a good deal of uncertainty as far as the timing of
rainfall and amounts, but for now the NBM is showing a fairly high
likelihood of seeing over an inch of additional rainfall across
much of southern and central Arizona.

&&

.AVIATION...Updated at 0010Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
The main aviation weather concern will be the arrival of
widespread light to moderate rainfall this evening, resulting in
potential low CIGs and VIS. Heading into this evening (mainly
around 02Z-04Z), a batch of rain will begin to move in from the
west. As this occurs, CIGs/VIS will rapidly deteriorate into the
MVFR category with a 20-40% chance of CIGs dropping even further
into the IFR category. A few embedded thunderstorms will also be
possible as this activity moves through with the fropa. The better
instability is currently north of the metro. The heaviest
rainfall/embedded thunderstorm activity with potential IFR
CIGs/VIS is expected between 05Z-09Z. Current southwesterly winds
with occasional gusts of 20-25 kt may briefly shift out of the
southeast as the initial band of moderate rainfall moves through
the Phoenix Metro. Conditions will slowly improve as the rain
tapers off overnight and CIGs rise back to around 4-5 kft into
early tomorrow morning. There may be a few lingering SHRA/VCSH
early tomorrow morning before a brief break in the activity. By
mid-to-late morning SHRA/VCSH returns with a few isolated
thunderstorms possible through Friday afternoon and evening.

Southeast California/Southwest Arizona including KIPL and KBLH:
The main aviation weather concern will occur through this evening
as widespread shower activity will bring with it low CIGs and VIS.
This shower activity is continuing to push across parts of SE CA
and SW AZ. CIGs are expected to drop to around 4-5 kft at KIPL
when the heaviest rain moves through early this evening. There is
about a 20% chance for KBLH CIGs to drop into the IFR category at
times as the heaviest shower activity pushes through early this
evening. Conditions improve post fropa with rainfall ending and
CIGs expected to rise into VFR. Winds will favor a northeasterly
component at KIPL before switching to the west this evening. At
KBLH, winds will predominantly favor a SW component. Winds at both
terminals will pick up in speed late tomorrow morning/early
tomorrow afternoon with speeds around 10-15 kt and with gusts of
20-25 kt.

&&

.FIRE WEATHER...
A cold front with light to moderate rain will move through the
area from this afternoon through early Friday. The increased
moisture will lead to minimum afternoon humidity levels above 60%
over the western districts today to 25-35% over the eastern
districts. Elevated humidities will persist into the weekend with
MinRHs above 40% through Saturday. Winds will become breezy over
much of the area today favoring the southeast through early
afternoon before shifting out of the southwest by late afternoon.
Wind gusts late this afternoon and evening may reach between
30-35 mph across portions of south-central Arizona. The breezy
conditions will persist during the day Friday with westerly winds
gusting to 25-30 mph in the afternoon. Below normal temperatures
will persist through the weekend with slightly drier conditions
spreading over the region. More unsettled weather is expected next
week with rain chances returning by Tuesday or Wednesday.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

DISCUSSION...Hirsch
PREVIOUS DISCUSSION...Kuhlman
AVIATION...Berislavich/Smith
FIRE WEATHER...Kuhlman