Sunrise 6:53 AM   Sunset 8:29 PM Moonrise 8:40 PM   Moonset 6:06 AM

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FXUS63 KGLD 250213 AFDGLD

Area Forecast Discussion National Weather Service Goodland KS 813 PM MDT Wed Apr 24 2024

KEY MESSAGES

- Significant severe weather is possible Thursday for most of the area with the main threats being tornadoes and very large hail. The threat is conditional as a cap could prevent storms from forming.

- A Fire Weather Watch and Red Flag Warning is in effect Thursday south of I-70 and west of Highway 25 for low humidity and strong winds.

- Blowing dust is also possible Thursday afternoon for near and south of the I-70 corridor.

UPDATE
Issued at 722 PM MDT Wed Apr 24 2024

Confidence is increasing in overnight convection affecting portions of the east and northeast counties. RAP soundings indicate an increasing environment for strong to marginally severe hail occurring with MUCAPE around 1400 j/kg, effective shear of 40-45 knots, EBWD shear in excess of 40 knots and lapse rates of around 8 C/km which should bring about the potential for hail around quarter size. PWATS are also in excess of 1 inch which would support a very heavy rain threat as well. Would be surprised if flooding becomes a concern due to the antecedent dry conditions along with fast storm motion. However if backbuilding does become an issue than may need to watch this more closely.

Confidence also does continue to increase in the potential for a significant severe weather event Thursday afternoon. Virtual all CAMS are now convecting along the dry line during the afternoon hours which is quite the change vs what was seen last night where everything was capped. It appears that the reasoning for this is due to the low stratus being favored a bit further north and east. A slight concern I do have is regarding upper level cirrus potential as RH values in the 400-200mb level do show around 30% RH values during the afternoon hours and signals of cirrus is also seen in RAP soundings. If this is the case this may be one of the many factors that may limit convective initation or sustained of any updrafts. Others are if the CAP is to strong and any potential impact that any outflow from overnight/morning convection may have; especially regarding the tornado potential. Despite all the continued uncertainties that do continue to shadow this event, the potential is there for a few intense supercells with very large hail and perhaps a significant tornado threat as 0-3 SRH values are around 200-225 and 0-1 SRH around 100 and does steadily increase into the later afternoon and early evening hours.

Regarding location for tomorrow; have been noticing a slight westward trend with where guidance wants to place the dry line.
Similar signs were seen with last week's severe event where the NAM was the relatively most accurate with the location of the dry line and other guidance were playing catchup. I feel the same thing is again applying in this scenario as well. Reasoning for this may be due to the undoing of soil moisture across the area; yes we have been dry lately but the area is coming off of a wetter past year; SPORT soil moisture also does support this theory as soil moisture has slightly improved over the past week. Overall current expectations is that the dry line does end up developing a bit further west perhaps around the Highway 27 corridor, creating a slightly larger warm sector.

SHORT TERM /THROUGH FRIDAY/
Issued at 248 PM MDT Wed Apr 24 2024

Tonight, the 850 mb LLJ will strengthen and shove more moisture into the CWA At the surface, easterly winds will cause upslope flow, leading to stratus and patchy to locally dense fog. This fog may begin around 10Z and potentially last until 18Z. The stratus will linger around longer than the fog and potentially cap the severe environment tomorrow afternoon/evening.

Also tonight, a shortwave looks to fire off a few showers and storms around 7Z. Small hail and some gusty winds are possible (5% chance), but confidence for severe weather is less than 2%. These showers and storms are expected to form near the eastern Colorado border and move east. The precipitation will exit the CWA in the late morning.
If these showers and storms linger and are fairly strong, this precipitation could deplete the environment of ingredients for the later storms.

After 18Z, southerly winds will pick up with gusts up to 35 kts in the southerly portions of the CWA Depending on where the dryline sets up, locales to the west will be much more dry. RH values to the west of the dryline will drop into the lower teens. This will create critical fire weather conditions for locations south of I-70 and west of Highway 25. Most locations will only briefly see the critical conditions, but there is high (80%) confidence that Greeley county will see prolonged critical conditions. If the dryline stalls out farther to the east and north, surrounding counties will have a good shot at hitting Red Flag Warning criteria, hence why the Fire Weather Watch has been left in place.

Blowing dust will also be possible (~20-50% chance) in locations along and south of Highway 36. Along the Kansas Colorado border will see the best conditions for blowing dust. Visibility reductions down to 2-3 miles are possible in plumes of blowing dust. Brown-out conditions cannot be ruled out.

The dryline will be the trigger for the severe weather in the eventing. SPC has added an Enhanced risk to the southeastern CWA for Thursday afternoon-night. This is based on a hatched/significant hazard for 30% chance of hail and 10% chance of tornado. For this event, the environment will be highly primed for tornado and hail hazards, but there will likely (60%) be a hefty inversion that will work to cap the updraft potential. If the cap does break, isolated discrete to clusters of severe storms will form and all hazards will be possible, with a focus on tornadoes and hail. The entire Tri- State area will have potential to see severe weather, but chances increase farther to the southeast.

Storms are expected to start firing around 18-21Z with the highlight of the severe storms being 21Z-06Z. The prime location for the severe storms will be in the southeastern CWA and the storms will move to the northeast. After 06Z, the severe weather threat will lower over the following 6 hours. During this time, we will begin to get the wrap-around precipitation from the northwest. These are expected to just be showers with a few weak thunderstorms embedded within. Less than 0.5 inches of QPF is expected with this system with most of that falling north of highway 36.

As the low pressure system leaves the area on Friday, strong northwesterly winds are expected to follow. Gusts up to 40 kts are already expected due to the pressure rises.

Temperatures overnight tonight and tomorrow night will cool to around 50. High temperatures tomorrow will be highly dependent on the dryline location and extent of the stratus. Under the stratus, highs will only reach the upper 60s to lower 70s. In the southwest, behind the dryline, low to mid 80s are forecast. Friday will be a bit more uniform with the northwestern CWA only warming into the mid 60s and the southern CWA reaching into the mid to upper 70s.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
Issued at 254 PM MDT Wed Apr 24 2024

A low pressure system will lift to the northeast across north central Kansas and south central Nebraska Friday evening. Overnight, there will be a 20-50% chance of showers and a few thunderstorms across areas mainly along and east of Highway 26.

Another low pressure system will lift to the northeast, out of the Four Corners region Saturday, bringing additional chances of precipitation to the area. Chances (40-80%) for showers and thunderstorms will increase west to east through the day as the system moves across the CWA Saturday night into Sunday, shower and thunderstorm chances continue as wrap around moisture impacts the region. Winds are also expected to increase on the back of the system.

Zonal flow sets up over the region on Monday and Tuesday.
Expect a drying out period during this time and a warm up.
Monday highs will be mainly in the low to mid-70s. Afternoon highs on Tuesday will be in the 70s and 80s.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
Issued at 511 PM MDT Wed Apr 24 2024

Breezy conditions will continue into the evening hours. The main concern, especially for the first portion of this TAF period will be stratus and patchy fog as moisture advects into the area. Currently, thinking stratus will be the main aviation concern as fog may be patchy in coverage as wind may lead into the "dissolving" of fog so will utilize VCFG for this. IFR to LIFR appears to be likely at each terminal. Some nocturnal convection may impact KMCK tonight around 06Z so will use VCTS until confidence increases in terminal being affected. Thursday afternoon may see some storms, perhaps severe during the afternoon hours with all hazards on the table. Exact timing due to initation issues exists currently so remain aware for updates.

GLD WATCHES/WARNINGS/ADVISORIES
KS...Fire Weather Watch from Thursday afternoon through Thursday evening for KSZ013-027-028-042.
Red Flag Warning from noon to 8 PM MDT Thursday for KSZ041.
CO...Fire Weather Watch from Thursday afternoon through Thursday evening for COZ253-254.
NE...None.

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