Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/16/24


Area Forecast Discussion
National Weather Service La Crosse WI
954 PM CDT Fri Mar 15 2024 .KEY MESSAGES... - Near-critical fire weather conditions for Saturday with winds gusting 25 to 35 mph and minimum relative humidities dropping to around 30% or lower south of I-94. - Cooler than normal temperatures are expected Sunday and Monday with highs remaining in the 30s. Wind chills in the single digits to around 0 degrees are likely Monday morning. - Temperatures return to slightly above normal beginning Tuesday with the next chance for widespread measurable precipitation on Thursday. && .DISCUSSION... Issued at 220 PM CDT Fri Mar 15 2024 Tonight/Saturday: Upper level shortwave trough and a leading sfc cold front set to drop southeast out of Canada and push across the region tonight. Some frontogenetic forcing with the boundary along with a streaking 50 kt 850 mb low level jet. Forcing suggests at least small rain chances, but dry air currently in place along with saturation concerns will work to limit those. Afternoon mixing continues to dry out the near surface layer while short/medium range guidance holds any "deeper" saturation across northeast Wisconsin. Stretching southwest of there the moisture shallows out and may not be enough to hold any pcpn chances. Locally, low end chances (10-20%) are confined north/east of I-94. Minimal if any accums if realized. More impacts will be the winds associated with the front/leading edge of the shortwave. With the aforementioned low level jet a top the system as it moves through and lack of a stronger sfc inversion developing, mixing could/will still be realized. Gusts upwards of 30 to 35 mph are expected - roughly from midnight through 6 am. The winds should settle down a bit for Sat morning before picking back up Sat afternoon with mixing. However, saturation does increase post the front, and promises some broken low/mid level cloudiness - although trending north of I-90. Clouds will temper the mixing a bit - but drying in the near sfc layer is again expected along with winds gusts back into the upper 20s/lower 30s mph. With dry grasses and other fuels, near critical fire weather conditions are expected. More on that in the "Fire Weather" discussion below. Lastly, there is a low end shot that there could be enough instability as cold air a loft (+9 C 1000:850 mb lapse rates) suggests some convective potential. Considering the dry air concerns (and likely more drying), whether more than just some after CU would be realized is a question. No meso/short term model support for even a smattering of rain chances and will leave out of the forecast for now. Sunday - Monday: Significantly Cooler As we head into Sunday, an upper-level trough coming out of Canada will usher in a cooler airmass with 850mb temperatures of -13 to -15C in the deterministic 15.12z EC/GFS. Consequently, there is a fairly good signal for temperatures to head below normal, the first time for La Crosse and Rochester this month, with highs remaining in the 30s areawide. Overnight Sunday and into Monday morning temperatures will bottom out in the teens. With this in mind and some increased northwesterly surface winds of 15-20 mph ahead of an incoming high pressure center will allow for wind chills to tank into the single digits, some spots even below zero. With the Canadian airmass directly overhead on Monday, highs will remain below normal with temperatures not escaping the 30s for most. Monday generally will remain fairly clear with subsidence associated with the aforementioned high pressure system keeping skies largely void of cloud cover through Monday afternoon, especially further south across northeast Iowa and southwestern Wisconsin. Tuesday - Friday: Temperatures Rebound, Some Precipitation Chances As the aforementioned trough and accompanied surface high pressure departs the region, northwesterly surface flow will briefly turn to southerly allowing for warmer air to be advected into the Upper Midwest on overnight Monday and early Tuesday. This is ahead of a weak surface low associated with a piece of vorticity caught in the 500mb northwesterly flow pattern. However confidence in any meaningful precipitation is becoming lower as probabilistic guidance in the 15.12z EC ensemble has lower confidence (30-50% chance) for measurable precipitation with the 15.12z GEFS trending even lower (10-20% chance) for Taylor County on Tuesday. Otherwise, the main story for Tuesday and beyond will be the recovering temperatures as highs will rebound above average once again with highs across the region trending into the upper 40s to lower 50s south of I-94 (lower to middle 40s north of I-94). Expecting these highs to remain roughly steady-state through Thursday with a quasi-zonal to northwesterly upper-level flow pattern in place. Some uncertainty comes with a wave that approaches regarding precipitation amounts and type but confidence is increasing somewhat in measurable precipitation late week with the 15.12z EC ensemble showing increased probabilities (60-80% chance) for measurable precipitation. && .AVIATION /06Z TAFS THROUGH 06Z SUNDAY/... Issued at 950 PM CDT Fri Mar 15 2024 VFR conditions are forecast through the TAF period with a period of gusty WSW winds overnight tonight becoming NW on Saturday, gusting 25 to 30 kts. Mid-level clouds will increase overnight tonight with lower 3.5-5kft VFR clouds moving in during the morning on Saturday. A period of low level wind shear is possible for a several hour window overnight tonight as winds aloft increase, but with some mixing/gust likely there is not specific mention of LLWS in the TAFs. && .FIRE WEATHER... Issued at 220 PM CDT Fri Mar 15 2024 Minimum relative humidity values will remain between 25 to 40 percent as forecast soundings show fairly prime mixing days into next week. Saturday appears to be the main day of interest for fire weather concerns with minimum relative humidities dropping as low as the upper 20 percent range in spots. Certainly could see some overachieving, cloud cover dependent, in relative humidities with hydroplapse rates atop the mixed layer in the 15.16z RAP suggesting dewpoints dropping from -12C to -37C in the 700-800mb layer. This combined with increasing surface winds of 20 to 30 mph will allow for near-critical fire weather conditions during the day Saturday. Areas of greatest concern will be along and north of I-90 where minimal rainfall from earlier systems have kept fuels dry. The one significant unknown for Saturday will be how cloud cover trends will affect conditions during the afternoon. Model soundings show a very shallow saturated layer at around 4kft atop the mixed layer suggesting that low-level cloud cover will be possible. The question remains if afternoon mixing will help to clear this out which could allow our relative humidities to plummet. If cloud cover hangs does hang around, this would keep our temperatures down and consequently not allow our relative humidities to tank as effectively with ineffective mixing. Otherwise, as cooler temperatures move in for Sunday and Monday, fire weather concerns mitigate some although relative humidities are still expected to remain on the lower side with values forecast between 25 to 40 percent through Wednesday. As a surface high pressure system works its way south of the region, winds will slightly begin to decrease with winds by Monday decreasing to 15-20 mph. May have to watch Tuesday for additional fire weather concerns as temperatures begin to warm with clearer skies and increasing winds. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Naylor/Rieck AVIATION...KAA/JM FIRE WEATHER...Naylor
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
705 PM CDT Fri Mar 15 2024 ...New UPDATE, AVIATION... .UPDATE... Issued at 631 PM CDT Fri Mar 15 2024 Delayed onset of thunderstorms chances for the mid and and lower RGV until around midnight with area void of activity at this time. 22Z HRRR indicates western areas seeing activity roll in from the Sierra Madre after 02Z spreading east but weakening there after. Currently (0630 LDT), BRO WSR-88 Doppler radar is showing one storm approximately 40 miles west of Zapata county moving southeast at around 20 mph. We will continue to monitor for additional storms with instability still rather high and the cap weakening however there remains a strong cap over the eastern half of the County Warning Area. && .SHORT TERM... (Tonight through Saturday night) Issued at 253 PM CDT Fri Mar 15 2024 The short term forecast period starts off active, as parts of the Northern Ranchlands and Upper Rio Grande Valley have been put into an area of slight risk (level 2 out of 5) and marginal risk (level 1 out of 5) for severe weather this afternoon and this evening. While the forcing is not the best, the cold front that is north of Deep South Texas and the Rio Grande Valley will allow for some isolated showers and thunderstorms to develop. Any developing thunderstorms do have the potential to become supercell. The primary risk with any severe thunderstorms this afternoon and this evening is large hail, which could be baseball size or larger. There is also the threat of strong winds as well, however that is dependent upon how the thunderstorms organize themselves. Then there is the low probability of tornadoes as well. As for the rest of Deep South Texas and the Rio Grande Valley, the current situation sees the area in a general thunderstorm outlook, so showers and thunderstorms are possible, but not expected to be severe. The Weather Prediction Center also has the Northern Ranchlands in a marginal risk (level 1 out of 4) of excessive rainfall due to the heavy rain associated with the thunderstorms. The latest HRRR model run does show the development of thunderstorm over these areas thus adding to the confidence of the severe threat. Then for tomorrow a similar set up as today will allow for more active weather for the region. Currently the Storm Prediction Center has about half of the CWA in a marginal risk of severe weather, which includes the Northern Ranchlands, the Upper Rio Grande Valley, and parts of the Mid Valley as well. The other half of the CWA is in a general thunderstorm outlook. The Weather Prediction Center also has a marginal risk of excessive rainfall for tomorrow, but that is more limited to the Northern Ranchlands. As for the temperatures, tonight the lows are expected to be in the range of upper 60s to low 70s, with the cooler temperatures in the Northern Ranchlands, while the warmer temperatures will be in the Lower Rio Grande Valley. The high temperatures for tomorrow are expected to be in the 80s for all of Deep South Texas and the Rio Grande Valley. However some places in the Middle Rio Grande Valley may get to the 90s. Finally, the low temperatures for tomorrow night are expected to be in mostly the upper 60s, with a few places in the low 70s. Lastly, for those going to the beach or enjoying spring break, a moderate risk of rip currents is expected to continue through tomorrow. Wave heights are expected to still be in the range of 2 to 4 feet as well. && .LONG TERM... (Sunday through next Friday) Issued at 253 PM CDT Fri Mar 15 2024 A cut-off low over the southwestern US looks to remain in place through mid week supporting southwesterly flow aloft through the beginning of the period. A series of shortwaves moving over Deep South Texas will provide additional forcing and support rain chances through the first half of the period. The cut-off low looks to finally move further east Wednesday, likely kicking off a surface low over North Texas and providing additional forcing over Deep South Texas. At the surface, a weak cold front looks to move through the area Sunday. Enhanced forcing from a passing shortwave, weak frontal lifting, PW values around 1.5”, and CAPE values >2000 J/kg could support some isolated to scattered showers and thunderstorms ahead of and along the front. Rain chances will continue into Monday, however thunderstorm potential will diminish behind the front Sunday night as CAPE values decrease and we transition into a weak overrunning setup. Easterly to southeasterly surface flow looks to return Tuesday into Tuesday night. This will support increasing temperatures for the later half of the period as well as increased low level moisture. Additional rain is possible Tuesday, thanks in part to another shortwave moving overhead, though rain chances are capped at roughly 20%. Instability looks to increase Wednesday afternoon, coinciding with the increased forcing from the passing upper level trough. This will reintroduce the potential for isolated showers and thunderstorms into the forecast Wednesday afternoon into Thursday morning. High temperatures Sunday in the upper 70s to low 80s will be replaced with highs in the upper 60 to low 70s Monday and Tuesday thanks to continued northerly to northeasterly flow behind the cold front. As winds shift southeasterly on Tuesday, high temperatures will begin to climb, reaching the upper 80s to low 90s by Friday. Similarly low temperatures in the 60s Sunday night will continue to fall in the upper 50s to low 60 Monday and Tuesday nights, before climbing back into the 60s Wednesday night. && .AVIATION... (00Z TAFS) Issued at 631 PM CDT Fri Mar 15 2024 Ceilings to develop and lower overnight with MVFR and possible IFR around sunrise Saturday. At 00Z all areas are seeing VFR with MVFR ceilings expected to develop around or shortly after 03Z. Thunderstorm activity is possible over the western areas of Deep South Texas with a 20-30 percent chance of storms approaching KMFE after 06Z and after 09Z at KHRL or KBRO although confidence is low for storms tracking east of I-69C. Light southeast winds expected overnight with occasional higher gusts near 20 knots. && .MARINE... Issued at 253 PM CDT Fri Mar 15 2024 Tonight through Saturday night...Mostly favorable conditions are expected to continue through Saturday night. Light to moderate onshore flow is expected to persist alongside low to moderate waves. Isolated showers and thunderstorms are possible over the waters. Sunday through next Friday...Light to moderate southeasterly winds shift northeasterly Sunday with the passage of a cold front. Tightening pressure gradients and stronger winds behind the front will likely result in adverse marine conditions Monday, as seas build to 8 ft. Small Craft Advisories may be need throughout the day Monday. Winds look to weaken and shift easterly to southeasterly Tuesday as high pressure sets up over the northern Gulf. This will support light to moderate southeasterly winds and low to moderate seas through the remainder of the period. Isolated to scattered showers and thunderstorms are possible Sunday, Wednesday night, and Thursday. Some brief periods of light rain are possible Monday and Tuesday. && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 72 84 70 81 / 20 10 20 20 HARLINGEN 69 86 67 82 / 30 10 30 30 MCALLEN 72 89 70 86 / 20 20 40 30 RIO GRANDE CITY 70 87 67 84 / 40 30 50 30 SOUTH PADRE ISLAND 69 75 69 74 / 30 10 10 20 BAYVIEW/PORT ISABEL 69 80 67 78 / 30 10 20 20 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...64-Katz LONG TERM....60-BE AVIATION...59-GB
Area Forecast Discussion
National Weather Service Fort Worth TX
642 PM CDT Fri Mar 15 2024 ...New Aviation, Short Term... .SHORT TERM... /NEW/ Update: No major changes were made with this forecast update as the previous forecast remains in good shape. A dreary afternoon has set up across North and Central Texas with our latest round of showers and isolated thunderstorms pushing across the Metroplex. Additional showers and thunderstorms are moving across our north westernmost counties right now with another area of development across Central Texas. Severe weather is not expected at this time, but there could be small hail associated with a couple of elevated cores as we move through the evening. Weather conditions should gradually improve overnight tonight as a lull in precipitation overtakes the region. Another shortwave will push along a stalled front that is currently draped across Central Texas, allowing for on and off showers and thunderstorms once again across the region. For more information please read the previous discussion below. Reeves Previous Discussion: /Today through Saturday Afternoon/ Currently the upper shortwave is moving across the region, increasing isentropic lift over the post-frontal airmass. Showers and a few embedded thunderstorms will continue to migrate to the east-northeast across North Texas, weakening as they stray further into cooler, more stable air. Better chances for thunderstorms this afternoon are expected in Southern Central Texas and South Texas, closer to the slow-moving front and instability axis. Slightly better chances for strong to marginally severe storms will accompany our far southern counties mid-late afternoon. Thankfully North and Central Texas will have a lull in precipitation during the evening and overnight hours in between shortwave passages. There may be some isolated precipitation that skirts the southern CWA border between FWD and EWX/HGX, but most activity will remain to our south. As we`ll stay pretty cloudy throughout the next few days, so overnight low temperatures will generally fare warmer for most. Expect Saturday low temps in the upper 40s to low 60s. Another shortwave will transit across North and Central Texas on Saturday. Clusters of showers and storms will form to the west of our Big Country counties in San Angelo`s area of responsibility early-mid morning, and surge eastward over the course of the day. Current CAMs are not in exact agreement with the speed of the system, with the NAMNest favoring more of a stronger broken linear system with a faster movement. The HRRR is a bit on the more conservative side with this activity, being a few hours behind and much more messy in storm mode. The HRRR has generally handled the current storm cluster well, so am favoring this solution for now. We`ll continue to watch over new model guidance overnight to see how accurate the CAMs are in storm initialization. Once again, severe weather is not expected at this time for North Texas, but some stronger storms in Central Texas could produce hail. Otherwise, expect another cooler day with Saturday highs in the upper 50s out west to the upper 60s/low 70s out east. Prater && .LONG TERM... /Issued 332 PM CDT Fri Mar 15 2024/ /Saturday Night Onward/ Saturday`s convection will exit to the east Saturday evening as the shortwave responsible heads for the Central Gulf Coast region. A second shortwave embedded within the subtropical jet will bring another brief round of showers and isolated storms to Central Texas overnight Saturday night into Sunday morning. With a surface front remaining stationary just south of the forecast area, storms should be elevated in nature and largely sub-severe. Steep mid level lapse rates may still support quarter sized hail in a storm or two. North and Central Texas will then become situated between a persistent upper low over the Desert Southwest and a deepening trough over the eastern half of the CONUS, creating a brief period of ridging aloft. The eastern trough will help push a second cold front south through the region, reinforcing the seasonably cool airmass and dropping temperatures another 5 to 10 degrees for the start of the work week. Cool and dry weather will be the end result for the start of next week with lows in the 40s and highs in the 60s. The upper low to the west will finally become dislodged from its stagnant position and begin moving east on Tuesday. The system will cross the Four Corners region Tuesday night before emerging in the Plains on Wednesday. Moisture return should be sufficient for the development of scattered showers and isolated thunderstorms for the midweek period as isentropic lift strengthens in advance of the approaching upper low. The best rain chances should be Wednesday into Wednesday night as the system crosses the Southern Plains. Precipitation will mostly exit to the east on Thursday, but will keep some POPs going due to uncertainty regarding how progressive the upper low will be. Seasonably cool and dry weather can then be expected for next weekend as the system exits to the east and a cold front pushes south in its wake. 30 && .AVIATION... /NEW/ /00z TAFs/ Concerns...MVFR/IFR ceilings with VCSH/VCTS tomorrow afternoon. Another round of MVFR ceilings has overtaken the D10 terminals, and will likely stick around with brief periods of clearing through the evening. A stratus intrusion will setup across North and Central Texas during the early morning hours tomorrow, overtaking Waco by around 07-08z and the rest of the D10 terminals by around 09-10z. There is a medium chance for IFR ceilings through tomorrow morning into the early afternoon across all terminals. A low chance (20-30%) of LIFR ceilings does exist through the same timeframe, mainly for Waco but the rest of the D10 cannot be totally ruled out. An additional round of showers and thunderstorms will push through the region once again late tomorrow morning through the evening hours. Reeves && .PRELIMINARY POINT TEMPS/POPS... Dallas-Ft. Worth 57 66 56 68 48 / 10 80 50 20 10 Waco 60 68 58 67 48 / 10 80 60 40 10 Paris 54 68 55 68 43 / 10 60 50 10 5 Denton 53 64 52 66 43 / 10 70 40 10 5 McKinney 55 66 55 66 44 / 10 60 50 10 5 Dallas 57 66 57 68 48 / 10 70 60 20 10 Terrell 57 67 56 66 46 / 10 70 70 20 10 Corsicana 62 70 60 68 49 / 10 80 70 30 10 Temple 60 69 58 66 49 / 10 80 60 40 10 Mineral Wells 53 64 52 66 44 / 10 80 40 20 10 && .FWD WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service North Platte NE
628 PM CDT Fri Mar 15 2024 .KEY MESSAGES... - Quiet, dry, and breezy this weekend as a backdoor cold front sweeps through the area Saturday. - With the mild and dry conditions persisting, elevated fire weather concerns exist this weekend into the middle of the week. - Temperatures rebound back into the above-normal range generally in the 50s and 60s Monday through mid-week ahead of cooler temperatures with an increased threat of precipitation to close out the week into the weekend. && .SYNOPSIS... Issued at 303 PM CDT Fri Mar 15 2024 Recent GOES-16 WV and RAP 500-mb analysis showed a near stationary closed low pressure system spinning over the Desert Southwest. Further northwest of this feature, upper-level high pressure was pushing onshore over the Pacific Northwest. A potent upper-level shortwave was dropping southeast out of Manitoba into the Upper Midwest. At the surface, high pressure was centered over southwest Nebraska, extending across the northern and central Plains. The upper-level system over Manitoba is vertically stacked with surface low pressure noted with an attendant cold front extending west-southwest, advancing towards the US/Canadian border. Outside of some high clouds passing by, clear skies prevail across western and north central Nebraska this afternoon. As of 3 PM CT, temperatures ranged from 49 at Imperial to 54 degrees at Ainsworth. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 303 PM CDT Fri Mar 15 2024 Saturday and Saturday night... As the aforementioned closed low drops into southern Ontario and the northern Great Lakes region, the backdoor cold front will continue southward, knocking on northern Nebraska come daybreak on Saturday. The front will continue to advance across western and north central Nebraska through the day with the intrusion of colder air behind the frontal passage expected overnight on Saturday. However, high temperature Saturday will be comparative to today ranging from the 50s to low 60s which is at or slightly above normal for mid-March. A tightening surface pressure gradient (SPG) will result in strengthening north north/northwesterly winds encompassing the area during the day on Saturday. Widespread gusts of 20 to 30 miles per hour will be common across the area with the strongest gusts up to 35 miles per hour over north central Nebraska, coinciding with where the tightest gradient is expected. These breezy winds begin to subside around sunset as the Great Lakes surface low continues southeastward, allowing the SPG to relax some. Meager cold air advection (CAA) behind the front will be felt overnight Saturday with lows falling into the 20s across the region. Sunday and Sunday Night... Highs on Sunday will only climb into the 40s with the exception of far southwestern Nebraska where mid 50s may be felt thanks to the frontal passage. North-northwest winds increase again on Sunday as the SPG tightens between surface high pressure nudging out of Canada and the low pressure system holding strong over the northeastern US. While the probability of wind gusts exceeding 40 miles per hour is non-zero, there is high confidence (>85%) that the gusts observed will remain in the 25 to 35 miles per hour range during the day on Sunday. The Canadian high centers over the northern Plains overnight on Sunday with lows falling below normal into the upper teens. With such breezy winds both Saturday and Sunday combining with afternoon relative humidity values bottoming out in the 20 to 30% range, fire weather concerns will remain elevated both days. At this time it doesn`t appear that critical conditions will develop but conditions will be closely monitored. && .LONG TERM /MONDAY THROUGH FRIDAY/... Issued at 303 PM CDT Fri Mar 15 2024 The upper-level pattern for the start of the long term period will be defined by an Omega Block. The stubborn closed low will continue across the Desert Southwest with high pressure centering over the Pacific Northwest and the Great Basin. On either side of these features, troughing will be evident across the Gulf of Alaska into the north Pacific and over the eastern two thirds of the CONUS. As the upper-level ridge continues to build across the western CONUS, temperatures rebound back into the 50s and 60s through mid-week with the warmest temperatures anticipated on Wednesday where highs in the upper 60s to low 70s appears likely across the area. With limited moisture and unseasonably warm temperatures, fire weather concerns will remain elevated through Wednesday. As we head into Thursday, quasi-zonal flow aloft will set up with the upper-level low currently across the Desert Southwest makes way across the southern Plains. Beyond this, considerable differences amongst model solutions exists on the overall synoptic flow heading into the weekend. Most guidance does hint at the potential for a threat of precipitation returning across the region, however, many questions remain unanswered being nearly 7 days out resulting in low confidence at this time. One thing that does stand out is that this system has the potential to bring a notable cooldown compared to earlier in the week with highs falling into the 40s or potentially colder. This in lies the biggest question with this system, just how much polar air will move southward out of Canada? Will need to continue to monitor trends in the coming days with this system. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 628 PM CDT Fri Mar 15 2024 Deep sfc low pressure will move east through Ontario during the next 24 hours. The low pressure will continue to circulate dry stable air into wrn and ncntl Nebraska and the risk of MVFR or lower flight conditions is very low, less than 20 percent. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Viken SHORT TERM...Viken LONG TERM...Viken AVIATION...CDC
Area Forecast Discussion
National Weather Service Marquette MI
1009 PM EDT Fri Mar 15 2024 .KEY MESSAGES... - Dry weather gives way to a brief round of light rain showers overnight as a cold front moves through. Some snow may mix in at times. - A prolonged gale event on Lake Superior starts tonight and lasts into Sunday night. - Southwest winds turn gusty overnight, particularly across the Keweenaw. - Below-normal temperatures, continued blustery conditions into early next week and accumulating lake-effect snow potential are expected Saturday night into Monday. && .UPDATE... Issued at 1007 PM EDT Fri Mar 15 2024 Water vapor imagery and RAP analysis show a vigorous shortwave dropping se into northern Ontario. Associated 995mb sfc low has moved out of Manitoba into northern Ontario and is located to the nw of Pickle Lake. Most of the pcpn associated with this system is occurring to the n of the International Border, but some -ra has developed southward into far northern MN this evening. Closer to home, clouds are thickening, and temps range from the mid 30s to mid 40s. Fcst appears to be in good shape with respect to pcpn chance tonight. For most locations, pcpn chc will only last 1-3hrs with pops ranging from 20-30pct far w to s central to 50-60pct Keweenaw and to around 80pct e where best chc of column saturation occurs. As for winds, even though a ~50kt low-level jet will translate across the area just ahead of cold front, fcst soundings show stability will work to limit mixing to higher winds overnight. Strongly considered dropping wind advy for the Keweenaw, but there is a small window (1-2hrs) just after fropa with the wind shift to a more favorable w direction where gusts may still reach 45mph. That said, with very weak caa, stability will still be an issue. Pres rise/fall couplet is not particularly sharp either for an isallobaric boost. Wind advy valid time was trimmed back to the immediate postfrontal period from 07z-12z. && .SHORT TERM /THROUGH TONIGHT/... Issued at 226 PM EDT Fri Mar 15 2024 Skies are staying sunny across most of the area so far this afternoon with weak ridging extending from a surface high sprawled out over the Plains. A deepening surface low is analyzed over Manitoba, resulting in a turn over to southerly flow over the Great Lakes. This is helping to keep temperatures quite mild, with most of hte area well into the 40s already. Expect temperatures to top out in the upper 40s to lower 50s across most of the area today. Mid and high level clouds should start to spread into the western UP closer to sunset. The surface low continues to track eastward through northern Ontario tonight, with a trailing cold front extending southward through the Great Lakes. SW winds pick up ahead of it, gusting to 20 to 30 mph overnight. Stronger gusts around and even in excess of 40 mph are possible across the Keweenaw for several hours. This will likely necessitate the issuance of a wind advisory overnight. The passing front will also touch off a round of rain showers, beginning by midnight in the western UP and quickly exiting east into the pre- dawn hours. Some snow may also mix in at times in the typically cooler spots, but with most of the area hovering in the mid and upper 30s for most of the night, significant snow accumulations are not expected. Behind the front, chilly WNW flow will result in the development of light lake effect snow showers by Saturday morning. && .LONG TERM /SATURDAY THROUGH FRIDAY/... Issued at 348 PM EDT Fri Mar 15 2024 Well, Winter is finally deciding to show up a little now that we`ve entered into Meteorological Spring! Normal to below normal temperatures dominate the extended period as we see generally light lake-effect snowfall across the northwest to north snow belts this weekend through early next week. Additional snow chances are also possible late next week too as the troughing pattern remains over the Northeast and Upper Midwest. Additional details to the forecast follow below. The cold front of the shortwave digging through northern Ontario drops across the U.P. Saturday from northwest to southeast throughout the day. As this occurs, we should see snow showers beginning over the western U.P. across the northwest snow belts and precipitation showers (mainly rain in the morning) over the eastern U.P. transition to pure lake-effect snow by the late afternoon hours. While the cold air advection (CAA) and lake-effect cloud cover will keep our region fairly insulated and cool Saturday, we could still see highs temperatures fight to get into the mid 40s across the south central as cloud cover may be more broken up over there. Likewise, temperatures over the northwest/the Keweenaw are expected to be at their zenith during the morning hours as the cold air advection slowly drops temperatures from the mid 30s to around 30 throughout the day. Blustery northwesterly winds are expected behind the cold front, with the Keweenaw possibly (65% chance) gusting up to 40 mph throughout the day. It`s possible, although not likely (25% chance) that we could see a few gusts up to 45 mph here and there in the afternoon. Otherwise, expect the winds across the rest of the U.P. to gust up to 25 to 35 mph. Snowfall accumulations look to be fairly slushy and limited to the higher elevations of the western U.P. until the overnight hours. On Saturday night, a secondary cold front dropping down from northern Ontario intensifies lake-enhanced snowfall across the northwest to north snow belts. CAMs show moderate to maybe (50% chance) heavy snow bands moving across the northern U.P. Saturday night. With the blustery conditions continuing ahead of and behind the secondary cold front, thinking it`s very likely (90%+ chance) that we see some patchy blowing snow along the Lake Superior shoreline. With the SLRs initially being near 10:1 to the mid teens by around midnight, we could see a slushy dusting hit the roads before fluffier snowfall settles over the northern U.P. As the lake-effect snowfall continues into Sunday, the main impacts look to be slick roads and reduced visibilities at times. Therefore, be sure to drive with a little extra caution if you plan on traveling to church/the grocery store/etc. Sunday. As ridging slowly builds in from the west Sunday evening through Monday, expect the lake-effect snowfall to decrease. The ridging looks to take the lake-effect snowfall out of our area by late Monday afternoon. However, there is a chance (30%) that we could see light snowfall return again to the area Monday night and Tuesday due to another shortwave digging through the Upper Midwest. Ultimately, thinking we could see 2 to 7 inches across the north to northwest snow belts Saturday night through Sunday night, with minor accumulations expected Monday into Tuesday. As we move into the middle to end of next week, expect to see shortwave activity across the region, causing us to see some light snowfall chances from time to time. With a rex block setting up over the Western U.S. and a general troughing pattern remaining over eastern Canada, normal to below normal temperatures are expected to continue. While the chance is small (<10%), the deterministic 12z GFS is hinting at a quick-hitting significant snowfall event across the U.P. next Thursday night through Friday. On the other end of the spectrum, the deterministic 00z ECMWF keeps us dry with the shortwave activity generally missing us to the south from Wednesday onwards due to localized high pressure ridging over us. Thus, whether we see snowfall or not for the end of the extended period will depend on where the localized high pressure ends up; if to our north, the chances become more likely. But if it moves over us or to our south, the chances become less likely. && .AVIATION /00Z TAFS THROUGH 00Z SUNDAY/... Issued at 802 PM EDT Fri Mar 15 2024 VFR is expected at IWD/CMX/SAW tonight despite a cold front sweeping thru the area in association with low pres tracking across northern Ontario. Low-level jet just ahead of the front will lead to a 3-4hr period of LLWS at all terminals tonight. Sfc winds will be gusty at times, but strongest wind potential will be at CMX where winds may gust to 35+kt for a short time immediately after fropa overnight. On Sat, increasingly colder air moving into the area along with daytime heating will result in gusty wnw winds of 30-35+kt at all terminals, strongest at CMX. Cyclonic flow and deep moisture will also support scattered -shsn across the area, including -shrasn in the morning. Cigs may slip to MVFR for a time during the morning/early aftn at IWD. Otherwise, VFR should prevail at all terminals on Sat though MVFR vis will be possible with any passing -shsn. && .MARINE... Issued at 348 PM EDT Fri Mar 15 2024 Southwest winds of 20 to 25 knots over the western half of Lake Superior this afternoon increase to gales up to 40 knots late tonight ahead of a cold front passing through from northwest to southeast; the greatest winds are expected in the north central lake around 1-3 AM EDT. Expect the winds to veer to the northwest Saturday as gales up to 35 knots are expected from time to time across the lake. Winds could (50% chance) gust up to as high as 40 knots over the eastern half Saturday afternoon through evening ahead of a secondary cold front moving through the area Saturday night. Behind the secondary cold front, winds veer to the north, with gales up to 35 to 40 knots being seen over the central and eastern lake late Saturday night into Sunday. As the pressure gradient weakens over the area Sunday afternoon into Sunday night, the winds slowly decrease with time, becoming northerly winds of 20 to 30 knots across the central and eastern lake Monday morning. With high pressure ridging building into Lake Superior Monday, the winds weaken to 20 to 25 knots over the eastern half as they back to the northwest. With another shortwave possibly moving through the Upper Great Lakes Monday night through Tuesday, we could see winds restrengthen again (40% chance). Additional shortwave activity could (35% chance) bring higher winds back across Lake Superior into Wednesday too. With the higher winds and colder temperatures expected over the next several days, we could see some moderate freezing spray late Saturday night through Monday. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Wind Advisory from 3 AM to 8 AM EDT Saturday for MIZ001-003. Lake Superior... Gale Warning until 8 AM EDT /7 AM CDT/ Sunday for LSZ162- 240>242-263. Gale Warning until 2 AM EDT Monday for LSZ243-244-264. Small Craft Advisory from 2 AM to 8 AM EDT Saturday for LSZ245>251. Gale Warning from 8 AM Saturday to 2 AM EDT Monday for LSZ245>251-265>267. Lake Michigan... Small Craft Advisory from 5 AM Saturday to 8 PM EDT Sunday for LMZ221-248-250. && $$ UPDATE...Rolfson SHORT TERM...LC LONG TERM...TAP AVIATION...Rolfson MARINE...TAP
Area Forecast Discussion
National Weather Service Phoenix AZ
502 PM MST Fri Mar 15 2024 .UPDATE...Updated Aviation Discussion. && .SYNOPSIS... A low pressure system will result in widespread showers and isolated thunderstorms across the region through the remainder of this afternoon and into the evening. Any thunderstorms that develop will capable of producing locally heavy rainfall, small hail, and gusty winds. Rain chances will continue to linger through early next week, mainly over the Arizona High Terrain as the low pressure system meanders over the region. Well-below normal temperatures are expected for today but will gradually warm up through the weekend and into next week. && .DISCUSSION... Showers and isolated thunderstorms continue across parts of the forecast area in response to a potent cutoff low currently centered over far western Arizona near Yuma. Rainfall amounts thus far today have been highest across high terrain areas east of Phoenix where training showers have led to observed totals in excess of 0.75" with some areas seeing amounts in excess of 1.00". Amounts elsewhere from shower activity across the lower deserts have been light so far, mostly under 0.10" with some areas closer to 0.25". Rain chances will be greatest this afternoon along with the threat for thunderstorms. Temperatures today will be well below normal (~10-15 degrees below normal) as highs only top out in the low to mid 60s across the lower deserts. Going through the afternoon, mid-level lapse rates will continue to increase across south-central Arizona as the proximity of the cold core pushes closer with the upper low gradually shifting northeast in far western Arizona. Instability will continue to increase for this afternoon with current RAP analysis showing some MUCAPE around 100-250 J/kg across the Arizona lower deserts and closer to 500 J/kg east of Phoenix. The latest 12Z HREF guidance keeps the greatest instability further to the east across eastern Arizona, while MUCAPE values are expected to generally be around 100-300 J/kg across south- central Arizona. Though instability will be a bit limited, coupled with upper level divergence over the area along with 0-6 km shear values upwards of 40-50 kts will promote convective development across south-central Arizona with a few stronger, organized thunderstorms possible. The primary threats with thunderstorms will be small hail, locally heavy rainfall perhaps leading to some nuisance flooding, and gusty winds. In fact, a few thunderstorms so far this afternoon have already produced some small hail in a few areas. WPC QPF storm total amounts around the Valley are around 0.20- 0.40", 0.50-1.00"+ to the east across the southern Gila County high terrain, and lighter amounts up to 0.10-0.25" to the west across southeast California and southwest Arizona. CAMs indicate some training of showers and thunderstorms will be possible that could lead to locally higher rainfall amounts. Additionally, areas that end up under a thunderstorm could see localized amounts upwards of 0.50-1.00", though the fast-moving nature of these thunderstorms will limit their residence time over a given area. Snow levels today will remain high enough to limit light snowfall accumulations to the high elevation peaks in southern Gila County. For Saturday morning, depending on how much rainfall we see today some patchy fog development may occur in a few areas such as northwest Pinal County as clearing skies and light winds are expected in these areas. Through the weekend and into early next week, the upper-level cutoff low will continue to meander over the Southwest CONUS before guidance show the Rex Block pattern breaking down and the upper low pushing out of the region during the middle part of next week. Rain chances will linger for some areas Saturday but will be significantly lower compared to today with shower/thunderstorm activity expected to be more isolated. Chances will primarily favor high terrain areas with slight chances out across parts of La Paz County and far northern Maricopa County given the proximity of the low and thus where some of the better instability will be. PoPs become primarily confined to the northern Arizona high terrain and into parts of southern Gila County Sunday through early next week. Once the low shifts east mid next week, weak ridging/quasi-zonal flow is expected to prevail through the remainder of the week with increasing going into next week in regards to potential troughing returning the region. Temperatures will warm up gradually warm up through the weekend with highs returning to near normal readings by Monday. NBM temperatures further warm up into the low to mid 80s across the lower deserts going into the middle part of next week. && .AVIATION...Updated at 0001Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: The main area of SHRA has moved of to the north and east of Phoenix terminals, however VCSH and brief -SHRA are still anticipated through 01-02Z. Conditions should then remain dry through Saturday, with rain chances under 10% Saturday afternoon. CIGs are currently around 5-6K ft with cloud coverage expected to further improve to FEW to SCT 5-6K ft across Phoenix later this evening and tonight. SCT to BKN 5-6K ft is then expected Saturday afternoon. There is some uncertainty with the wind direction the next few hours, but as of now a N to NE is favored. E winds will then prevail tonight through Saturday morning with light speeds, aob 7 kts. Light winds continue during the day Saturday, with some variability midday before shifting W in the afternoon. Southeast California/Southwest Arizona including KIPL and KBLH: VCSH is ongoing at KBLH and should continue for another 1-2 hrs. Showers in and west of the Laguna Mtns may survive into the Imperial Valley between 02-07Z this evening, but confidence is too low to include in the TAF. Additional shower chances are expected Saturday afternoon, with a slight chance (20%) at KBLH, beginning around 21Z, and lower chances at KIPL. The showers, and perhaps an isolated storm, Saturday afternoon will be capable of producing W to NW wind gusts up to 25 kts. Winds otherwise will remain light at both terminals, aob 7 kts, through Saturday. Directions will favor a W to NW at both terminals, with periods of variability. VFR conditions are expected to prevail through Saturday, with lowest CIGs around 5-6K ft. && .FIRE WEATHER... A low pressure system will result in an increase in the areal coverage of showers and isolated thunderstorms for today. The most widespread activity is expected across south-central AZ. The chances for showers will linger through the weekend into early next week, however, the overall coverage will be significantly less with the best chances confined mainly across the higher terrain areas of northern and eastern AZ. MinRHs will be significantly elevated today with values ranging between 30-50% across the western districts to between 50-70% across the eastern districts. Winds outside of any shower and thunderstorm activity will remain generally light through next week. MinRHs will remain elevated through the weekend but then gradually lower through next week. Temperatures will remain below normal through the weekend before warming to near to slightly above normal through next week. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Smith AVIATION...Benedict FIRE WEATHER...Lojero
Area Forecast Discussion
National Weather Service Salt Lake City UT
444 PM MDT Fri Mar 15 2024 .SYNOPSIS...A weaker downslope wind event is expected overnight into Saturday, primarily for portions of eastern Cache Valley and prone areas near the terrain in eastern Davis/Weber County. Meanwhile, closed low will continue to bring substantial snow to southern Utah mountains, and potential for some lower elevation snow accumulations across south central to southeast Utah as well. && .SHORT TERM (Through 12Z/6AM Sunday)... * Key message 1: Setup remains favorable for another night of moderate downslope winds in prone areas along the Northern Wasatch Front and Eastern Cache Valley. With a weaker signal noted overall, wind gusts are expected to fall generally within the 40- 55 mph range overnight into Saturday morning, with the highest gusts likely in the Centerville to Park Lane and mouth of Weber Canyon areas. * Key message 2: A significant snow event will continue to unfold across southern Utah through late Saturday. Snow levels will drop overnight into early Saturday, and then increase through the day, but periods of higher precipitation rates may help lower snow levels at times. Additional snow accumulations of 6 to 12 inches are expected for the mountains west of US-89, and an additional 1 to 2 feet are expected for the mountains east of US-89 (locally up to 3 feet). Further accumulations of around 4 to 8 inches are possible for Capitol Reef and Bryce Canyon. Less certainty noted at lower elevations, but a trace to up to 4 inches will be possible for some lower elevation valleys/locations. Forecast region continues to find itself under a somewhat atypical pattern as a cutoff mid/upper level low continues to churn in the Desert Southwest. In combination with a mid/upper high making very minimal inland progression in the PacNW, deeper layer flow atop the local forecast area remains primarily from an easterly direction. 700mb flow this afternoon has been weaker than that of yesterday, and as a result, haven`t seen as much in the way of widespread gusts, and rather more some moderate lingering gusts in locally favored downslope areas along the northern Wasatch Front and eastern Cache Valley. Overnight into Saturday, the ingredients for downsloping winds remain, albeit in a more limited fashion. 700mb winds for example look to be more in the 25-40 kt range overnight. High resolution guidance shows this potential accordingly, with downsloping winds ramping back up by late evening, peaking near to a bit after sunrise, and then diminishing by late morning into the afternoon. Best signal in guidance is noted along the eastern Cache Valley, though given the limited gusts with more favorable ingredients the prior night, will say there is a bit of uncertainty in how strong and how long gusty conditions last. Still, given the signal, opted to issue a Wind Advisory, with most impacts likely remaining east of the US-89/US-91 corridor. Aside from the eastern Cache Valley, the signal once again looks favorable for areas near the terrain in eastern Davis/Weber counties, particularly for the locally favored areas near Park Lane and near the mouth of Weber Canyon. Similarly, a Wind Advisory will persist overnight into Saturday. Elsewhere in typical downslope prone locations along the northern Wasatch Front, some gusty conditions are likely overnight, but general consensus keeps magnitudes below advisory criteria. A similar progression of winds is anticipated Saturday on into Saturday night with downslope potential, but expect magnitudes to be lower and likely remain at sub-advisory levels. The cutoff low is also resulting in widespread precipitation across southern Utah. Given the position of the low, a fetch of Pacific moisture will continue to wrap around the low and promote moist east/southeasterly upslope flow. Have even seen what appears to be some embedded convective elements occasionally, helping further increase precipitation rates at times today. Low level temperatures continue to be one of the trickier forecast elements of the system. Many locations seem to be verifying much cooler than expected today, and 700mb temperatures are also seemingly coming on the cooler side of guidance. This (along with some rate driven enhancement) has forced snow levels lower than expected today, and rather than see lower elevation snow switch over to rain, have seen more lingering snow (or mix) in areas that do not frequently see it. Even forcing snow levels down to around the NBM`s 10th percentile doesn`t seem to be enough to accurately handle the situation. As such, low confidence is noted in the lower elevation p-type, but as much as snow levels have struggled to increase during the day today, thinking we may see a bit more snow than initially anticipated in some of the low elevation areas of southern Utah before the event tapers off later Saturday. While predicated in part on where the more focused band of precipitation sets up, current forecast includes anywhere from around a trace to quarter inch of snow in locations such as Kanab and Hanksville, and potentially up to another 4 inches or so in places like Escalante. Additionally, could see some accumulating snow on the order of an inch or two along I-70 through the San Rafael Swell... So in general those planning in travel through southern Utah should be aware of the snow potential in less common areas. The next bit of uncertainty is in regards to where exactly and how quickly the more focused band of precipitation sets up. This will be dependent on how the cutoff low churns around the Desert Southwest, and in turn where the better juxtaposition of moisture/energy associated with the low end up. Currently this feature seems to have set up from roughly the Lake Powell area northwest through Escalante and nearby mountains. High resolution guidance suggests a reasonable scenario would be seeing this band gradually shift a bit more northward this evening into the overnight, with a gradual pivot to a more east-west orientation as it does so. That said, while some guidance sources such as the HRRR keep a more cohesive band, others scatter it out a bit more. Overall though, this will remain a feature to watch, as it could result in some locally higher amounts where it manages to have more residence time. Even then, outside of the more focused precip band, will maintain a favorable environment for more scattered (but still fairly widespread) showers. Mountains will continue to do well (especially those east of US-89 given the more easterly flow), and would anticipate a bit of locally higher amounts where the more cohesive band pushes into the terrain. Overall, by the events end, some of the more traveled areas of places like Bryce Canyon and Capitol Reef could see snow totals in the 4 to 8 inch range. The mountains will see continued substantial snow accumulations snow throughout the remainder of the event. Current forecast package includes an additional 1 to 2 feet for the mountains east of US-89, with locally up to 3 feet possible. For the mountains west of US-89, forecast includes additional accumulations of around 6 to 12 inches. Again, for those with any travel plans through southern Utah, be sure to try and check road conditions before heading out, and be prepared for possible winter driving conditions. Lighter and more scattered precipitation will linger through the back half of Saturday on into the overnight hours Sunday, but generally expect the event to gradually be winding down. .LONG TERM (After 12Z Sunday)... Generally minimal impacts to discuss in the long term portion of the forecast the Rex Block pattern will persist into mid-next week, with the model consensus generally wanting to break that pattern down by mid to late next week as the low to our south is finally kicked eastward as its picked up by the mean westerly flow again. Beyond that, model confidence wanes, with generally some sort of zonalish flow in place with about 50/50 ish probs of whether we`re dominated by a downstream ridge axis, or closer to a trough impinging on our western periphery. As the cutoff low to our south continues to remain nearly stationary, the precipitation and easterly winds aloft associated with it will continue to weaken. This will result in only scattered showers across southern Utah with minor QPF amounts. Given weak forcing, most of these showers will be diurnally driven and orographically forced. Conditions across northern Utah will run just above average high temperature wise. In addition, some enhanced easterly winds may pick up again Sunday morning as high pressure is reinforced into SW Wyoming with the low to our south helping to advect the cold air across the Wasatch from the east. The details on this will matter for exact peak wind gust potential. For now continue to advertise gusts in the 40-45 mph range for the typical enhanced canyon wind / downslope prone locations. && .AVIATION...KSLC...VFR will persist for the KSLC terminal throughout the period as conditions will remain dry with mostly clear skies. Occasionally gusty northeast winds to around 20 knots will be increasingly punctuated by period of lighter and more variable winds as we move into the overnight hours, and especially by tomorrow morning. This is thanks to continued downslope winds off the terrain to the east, which will cause easterly cross winds when reaching the terminal and otherwise, more lighter erratic wind directions when the terminal gets into the back eddy from the mountain wave. .REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail for the northern half of the airspace with dry conditions and gusty easterly downsloping winds increasing again tonight before diminishing again tomorrow during the day. Southern and central Utah will see low elevation rain and high elevation snow create MVFR/IFR conditions throughout most of the day owing to a cutoff low across the desert southwest. Additionally, winds will be easterly/northeasterly across southern Utah with occasional gusts. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Wind Advisory until noon MDT Saturday for UTZ104. Wind Advisory from midnight tonight to noon MDT Saturday for UTZ107. Winter Storm Warning until 6 PM MDT Saturday for UTZ117-125-127- 129. Winter Weather Advisory until 6 PM MDT Saturday for UTZ128. WY...None. && $$ SHORT TERM...Warthen LONG TERM...Church AVIATION...Church For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity