####018009429#### FXUS65 KPUB 060328 AFDPUB Area Forecast Discussion National Weather Service Pueblo CO 928 PM MDT Sun May 5 2024 .KEY MESSAGES... - High winds will spread across the region tonight through Monday morning. - Brief round of wind driven snow expected for the Continental Divide late tonight through Monday morning. - Critical fire weather conditions will be widespread for the San Luis Valley and portions of the plains during the afternoon and evening hours on Tuesday and Wednesday. - Very strong and gusty winds (near High Wind Warning criteria for some areas) are expected on Tuesday. Blowing dust will be possible across the lower elevations. - A few showers and high elevation snow showers will be possible for areas mainly north of Highway 50 on Tuesday through Wednesday. - Scattered showers and thunderstorms, with high elevation snow, will be possible on Thursday through Saturday, along with cooler temperatures. && .SHORT TERM /THROUGH MONDAY NIGHT/... Issued at 241 PM MDT Sun May 5 2024 Upper low over NV/UT will move eastward across northern CO tonight and into western NE by Monday afternoon. This will send a brief round of wind driven snow into the mountains along the Continental Divide tonight before snow diminishes from south to north Monday morning. Still getting around 4 to 8 inches across the higher peaks and passes with the potential for brief hazardous travel impacts during the overnight hours. Have issued a short duration winter weather advisory to highlight this potential. A bora cold front will cross the mountains late tonight into Monday morning spreading a round of high winds across the southeast mountains and into portions of the I-25 corridor around dawn on Monday. Gusts in the 60 to 75 mph range will be possible as the front crosses the mountains and strong downward forcing briefly transports higher momentum aloft to the surface. It will remain windy through the morning, but the high wind potential looks to diminish rapidly after 15z. Will upgrade the High Wind Watches to High Wind Warnings with the afternoon package. There is the potential for high wind gusts to impact portions of western Pueblo and southwest El Paso as well though coverage looks limited to locations west of I-25 and close to the mountains. Very dry air behind the front will overspread southern CO on Monday resulting in a return of critical fire weather conditions across southern CO for locations where fuels are deemed critical by land management agencies. This will be confined to the San Luis Valley, the lower slopes of the Wets and Sangre De Cristo Mountains, the Wet mountain valley, and the Comanche grassland locations of Otero, eastern Las Animas and Baca counties where greenup has been delayed due to dry conditions this spring. However, given the magnitude of the winds on Monday, any activities which could start a wildfire is discourages as any fuel sources available to burn could become volatile with such strong winds. Otherwise, temperatures will remain mild, though cooling to a little below climo for Monday behind the front. Winds tail down in the afternoon though it will still remain windy with critical fire weather conditions. Think any blowing dust will be confined to the morning hours with the strongest winds associated with the frontal passage. -KT && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 241 PM MDT Sun May 5 2024 Monday night through Wednesday... After passage of the bora front Monday night, there will be a lot of forward shear on the backside of the front within the westerly flow at the 700 mb level moving over the entire CWA on Tuesday, with some 50 kt pennants showing up over the southern I-25 corridor with some of the deterministic models. This is going to translate to very strong and gusty winds down to the surface, which could occasionally reach High Wind Warning criteria over certain areas by later in the day on Tuesday. Along with this will be blowing dust possible across the lower levels, as well as critical fire weather conditions for the San Luis Valley, and portions of the plains by later in the afternoon and through the early evening once RH values tank. The winds look to become the strongest right around peak heating in the middle of the day once there is the best mixing present. Although, confidence of persistent High Wind Warning criteria is not high at this time, given that cross sections display only forward shear, and thus deep mixing would be the only forcing that could get these stronger winds down to the surface. Stronger winds will be more likely across the higher elevations of the Sangre de Cristo Mountains, which appear at this time to have a higher probability of needing a High Wind Warning vs other mountains. Again, there is still some uncertainty of this, depending on the position of the longwave trough and where the strongest 700-500mb flow will be. The San Luis Valley will also be another area in question for needing a potential High Wind Warning on Tuesday, if deep layer mixing does occur. With winds as the main concern, precipitation will be generally sparse on Tuesday, and more or less confined to areas north of Highway 50. The northern Sawatch and Mosquito Ranges will be the locations most likely to receive any measurable precip, with a few inches of snow possible. Downsloping winds will also adiabatically warm up the lower levels, with highs topping out in the upper 70s to low 80s across the plains. The higher terrain will be relatively cooler, and either at, or slightly below, the seasonal average for this time of year. By Wednesday, a frontal boundary will move through with winds shifting more out of the northerly direction over the plains. This will help to allow for colder air advection, with temperatures being anywhere around 10 to 15 degrees cooler for highs. Strong and gusty winds will continue to be out of the more west to northwesterly direction over the higher terrain, yet not as strong. There will still be some showers possible over the central mountains, and also for areas of the Pikes peak Region (PPR), Ramparts, and Palmer Divide. There will still be widespread critical fire weather conditions over the San Luis Valley, although the northerly flow for the plains will help to mitigate fire concerns over the plains, although there could still be some areas which are vulnerable due to critical fuels over eastern Las Animas County that may need fire weather highlights for the afternoon hours. Thursday through Saturday... Chances of precipitation for all of SE Colorado will ramp up during this period in the forecast, along with cooler temperatures. The pattern will remain unsettled as there will be a deepening major shortwave trough that is going to be slowly progressing towards the south and over the region on Thursday, then splits with an upper level low retrograding back towards the southwest on Friday. There is a general consensus between the deterministic models as to what this U/L low will do once it becomes cut-off somewhere over the Great Basin region, although there is some deviation between the solutions. The GFS has this remaining further to the north, and then moving towards Colorado with a much more extensive mid-level moisture advection. The Canadian is more similar to what the GFS is showing, while the ECMWF is a much drier solution with the position of the U/L low being further to the southwest and only allowing for mid-level moisture to be more confined to the higher terrain with the plains remaining mostly dry. There is still some time to allow models to resolve this feature better in the upcoming days, and determine if the plains will be either more wet or more dry for both Friday and Saturday. It will be overall cooler, with highs running anywhere from 5 to 10 degrees below the seasonal average for most locations, especially on Friday. -Stewey && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 241 PM MDT Sun May 5 2024 Strong southerly winds will continue this evening with gusts up to 35 kts. Winds will decrease this evening but remain elevated and southerly through the night with the possibility of some periodic wind shear at KCOS overnight before strong winds increase again towards dawn Monday. All three terminals should see winds increase from the west gusting up to 40-45 kts on Monday. Conditions will remain VFR. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 10 AM MDT Monday for COZ058-060. Winter Weather Advisory until 6 AM MDT Monday for COZ066-068. Red Flag Warning from 10 AM to 10 PM MDT Monday for COZ224-225- 232-233-237. Fire Weather Watch from Tuesday morning through Tuesday evening for COZ224-225-232-233-237. High Wind Warning until noon MDT Monday for COZ072>075-079-080. High Wind Warning until noon MDT Monday for COZ078-081>083-087- 088. && $$ SHORT TERM...KT LONG TERM...STEWARD AVIATION...KT ####018007038#### FXUS63 KGRB 060328 AFDGRB Area Forecast Discussion National Weather Service Green Bay WI 1028 PM CDT Sun May 5 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - Patchy fog is possible late tonight until an hour or two after sunrise on Monday. - Relative humidity values are expected to drop into the middle 20s and 30s Monday afternoon. Recent rain, lack of strong gusty winds and continued green-up will limit fire weather concerns. - Next round of showers and storms arrives Tuesday morning. Best chance for thunderstorms will be Tuesday afternoon and evening. There is a small risk for a stronger storm especially for our western areas. && .DISCUSSION... Issued at 253 PM CDT Sun May 5 2024 Short Term...Tonight and Monday Fair weather cumulus clouds developed late this morning and continued this afternoon away from the bay and Lake Michigan. Temperatures climbed into the 60s, except only around 50 near the Lake Michigan shoreline. The lake breeze was beginning to move westward towards Green Bay and the Fox Cities. For the rest of the afternoon, the lake breeze should move into Green Bay and the Fox Cities late this afternoon. The passage of the lake breeze front will bring a wind shift to the southeast along with temperatures falling several degrees. For tonight, the fair weather cumulus clouds should dissipate around sunset. With clear skies and light winds overnight, some patchy fog is expected to develop toward sunrise on Monday. The fog is expected to be patchy and not dense with the amount of drying taking place today. On Monday, a sunny and mild day is anticipated with highs in the middle 60s to lower 70s away from the bay and Lake Michigan. Afternoon relative humidity values should drop into 25 to 30 percent range across the far north with 30-40 percent away from the bay and Lake Michigan. Southeast winds will increase Monday afternoon with gusts of 15 to 20 mph expected at most spots. Long Term...Monday Night Through Sunday Several opportunities for rain this week as a general unsettled pattern dominates. No great signal for anything too significant in terms of storms or rainfall, though we'll have to keep eye on late Tuesday if destabilization can occur. The Monday night through Tuesday evening time frame will likely be when the most rainfall occurs this week. Deep low sub 985mb will be lifting northward across the northern plains. Occluded front well ahead of the low will be interacting with PWATs up to 1.25 inch approximately the 90th percentile for this time of year. SE flow ahead of this front will also be drawing in dry air tied to departing high pressure. Slower trend for rain shower arrival that started showing up 24hr ago remains today, if not even slower yet. Expect most cwa to remain dry on Monday night, except maybe the very far western fringe. Eventually though band of moderate showers (lasting 3-6 hrs at any one location) will swing across the area beginning mid to late morning on Tuesday. Lingering dry air could keep parts of east-central and northeast WI from not seeing rain arrive until at least early Tuesday afternoon. Current forecast temperatures show decent range with expected showers and SE winds keeping central to north-central/northeast WI cooler while earlier ending of steady showers and winds shifting to the SW could allow temps to reach near 70 south of Wisconsin Rapids to Oshkosh. Best chance for thunderstorms comes Tuesday afternoon and evening as models show a thin band of instability (MLCAPE now increasing to 500 to as much as 1000 J/kg) building from western to central WI. Additionally mid-level lapse rates approach 7.5-8.0 C/km during this period owing to cooler air aloft as H5 temps drop below -20c beneath elongated trough from Montana to the western Great Lakes. Seems another embedded shortwave arrives over west- central WI late afternoon to kick off the additional convection chances. Forecast soundings show relatively low wet-bulb zero heights (6-8kft) with inverted-V look. Effective shear is 30-40 kts. Timing will be key as if initial wave of showers moves through quicker, then there would be more time to destabilize in the afternoon. SREF thunder/severe probs point to far southern WI for better severe potential, but think there is at least a small risk into our southwest areas. In terms of rainfall amounts the consensus of the ensembles point to likely (60-80%) of seeing at least 0.50 inch of rain but tail off to less 30 percent for seeing over 1". Wednesday through Thursday...Ensembles have come into decent agreement with a period of dry weather Wednesday morning as dry air behind an occluding front filters over the region. Dry conditions may not last long as the weakening cyclone moving east out of the northern Plains merges with a developing southern stream system returning rainfall to the region late Wednesday into Thursday. Possible some convection may occur late Wednesday mostly over central and western WI away from more easterly flow developing off Lake Michigan. These east winds may get a bit gusty on Thursday as they turn northeast once primary low pressure system begins to shift more to the central Great Lakes and Ohio Valley. Rest of the extended...Seems Thursday night into Friday will dry out. If clearing occurs earlier, some risk for fog or frost over north-central WI early Friday morning. Rather vigorous trough is on track to drop across the western Great Lakes by Saturday. Due to this, the risk for showers has increased for Friday night into Saturday but the chances for chilly min temps and some frost Friday night over the north has lessened. Will just have to see if the trend holds. Unsettled weather continues for the weekend as low pressure slowly drifts away and a reinforcing cold front drops across. && .AVIATION...for 06Z TAF Issuance Issued at 1028 PM CDT Sun May 5 2024 VFR conditions will prevail through the TAF period. The only exception could be for some MVFR visibilities across far north- central Wisconsin, especially Vilas County, towards sunrise on Monday morning. Mostly clear skies are expected overnight, with some high cirrus clouds at times across central and east-central Wisconsin. Fair weather cumulus clouds will redevelop, generally around the same height, late Monday morning and afternoon, then dissipate with sunset Monday evening. Surface winds will generally be light, with some LLWS expected to develop across central and north-central Wisconsin later Monday evening as low level southeast winds gust to 30-40 knots just off the surface. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Eckberg/JLA AVIATION.......Kurimski