Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/19/24


Area Forecast Discussion...Updated
National Weather Service Lincoln IL
807 PM CDT Mon Mar 18 2024 .KEY MESSAGES... - Hard freeze expected (greater than 90% chance) again tonight. Precautions should be taken to protect sensitive vegetation. - Dry and windy tomorrow, leading to elevated fire danger. There is a 70-80% chance west-southwest gusts surpass 40 mph at some point mid morning through early afternoon. - Small (10-15%) chance for accumulating snow in a narrow band across some portion of the area Thursday morning. 60-90% chance for another hard freeze Thursday morning. - Late Thursday night into Friday, additional precipitation is expected, with some snow mixing in mainly north of I-74. && .UPDATE... Issued at 807 PM CDT Mon Mar 18 2024 Other than the cold, it looks to be a quiet night tonight. Lows should to be mostly in the mid to upper 20s tonight. The latest surface analysis had a high centered over eastern OK with a surface ridge extending northeast through the mid MS River Valley. The high gets suppressed southward as a low moves into the western Great Lakes by Tuesday morning, increasing southwesterly winds across IL. Most of the clouds have moved east of the area, except for some near the IN border. Made some sky and temp modifications with the recent update. Otherwise, the forecast looks on track for tonight. Knutsvig && .DISCUSSION... Issued at 314 PM CDT Mon Mar 18 2024 A dreary, winter-like day in central Illinois, temps have only warmed into the mid to upper 30s this afternoon, and, despite the dry boundary layer, sporadic snow flurries have been observed mainly northeast of a Peoria to Paris line amidst sfc based instability poking into the DGZ. As that instability wanes with both the loss of sfc heating and eastward shift of coldest temps aloft this evening, those flurries should come to an end. However, weak cold advection will continue overnight on the northeast periphery of the sfc high, fostering temps dropping once again into the 20s. NBM suggests greater than 90% probabilities for a hard freeze (i.e., sub 28 degF low temps) and 50-80% chances (highest east of the IL River) for sub 25 degF lows tonight into tomorrow morning, which is certainly cold enough to damage sensitive vegetation. For this reason, we`ve once again issued an SPS to raise awareness and encourage those with tender vegetation to take precautions. HREF guidance is suggesting few, if any, clouds tomorrow morning, so we should be quick to radiationally warm up after sunrise. This will also allow some of the 40-45 kt WSW winds at 925mb to mix down to the sfc for quite the breezy morning. The NAMNest, being its usual self and likely overmixing the (hopefully decoupled) boundary layer, is suggesting widespread 50+ mph gusts beneath this LLJ around 5-8am tomorrow, which is the culprit for the HREF ensemble max. I don`t want to dismiss that as though it couldn`t materialize - especially given our winds have overperformed a bit lately - but it`s definitely the outlier of the CAMs. Nonetheless, the HRRR suggests an abrupt uptick in winds around 14z/9am, with gusts to about 45 mph for a couple hours thereafter, in line with the suggested peak theoretical gusts using the mixing technique from BUFKIT forecast soundings. At this point, there`s just not the confidence in a reasonable duration of near/above criteria (45 mph) wind gusts to issue a Wind Advisory, but we`ll let the evening and overnight shifts reassess that potential. Given these strong winds, RH values in the 25-35% range, and 10 hour dead fuel moisture values in the 8- 10% range, any fires that develop tomorrow could spread quickly. We`d like to encourage folks to limit burning, have fire suppression equipment ready if you intend to burn, and use caution with outdoor equipment; as always, do not carelessly discard cigarettes. Winds will veer to northwesterly and gradually ease behind an ill- defined cool front tomorrow afternoon and evening with a better shot of the cooler air aloft sliding southward into our area tomorrow night. Cloud cover and lingering wind will keep us from radiating out fully Wednesday morning, but will also suppress our afternoon highs with temps expected to fall shy of 50 everywhere north of I- 70. Wednesday night into Thursday morning, temps are expected to fall once again into the 20s with NBM suggesting a greater than 60% chance for a hard freeze north of a Beardstown to Robinson line, and a greater than 80% chance north of I-74. The bigger concern heading into Thursday morning, however, would be the (low) potential for snow. At this point, ensemble agreement was not high enough to even warrant PoPs as just a couple models are showing QPF...and there`s considerable spread in where they have it. However, wherever this QPF sets up, the thermodynamic environment characterized by modestly steep lapse rates (and saturation or near saturation) in the DGZ, 850mb temps of -2 to -5 degC, and sub freezing sfc temps would be conducive to a quick couple inches of accumulation along a narrow corridor. Stay tuned to the forecast for updates on this. With two systems - one diving in from the northwest and another lifting up from the south - merging as they move through/out of our area, another shot of precip is expected mainly Friday morning. At this point, the highest chance for wintry precip getting mixed in is north of I-74, and accumulations are not looking likely with this wave. Once again, though, stay tuned to the forecast for the latest, as it`s subject to change. Temperatures should stay near normal through Saturday, but then warm Sunday into Monday ahead of the next system. The evolution of this potentially potent storm is still in question, but most guidance takes it to our west which would lead to well-above normal temps for us particularly on Monday when several EPS members bring 70+ degF temps north to I-72. The CSU MLP brings a 5% contour for severe wx nearly as far north which seems reasonable; confidence is certainly low in severe potential given the possibility of poor alignment between most favorable kinematics (north) and thermodynamic support (south), but like the rest of the forecast we will keep a watchful eye on it as forthcoming model iterations give new insight. Bumgardner && .AVIATION... (For the 00z TAFs through 00z Tuesday Evening) Issued at 626 PM CDT Mon Mar 18 2024 VFR conditions are expected through the period. The winds will lose their gusts by 00-01Z and get it back early in the morning, around 13-14Z, from the southwest. Expect another breezy day tomorrow. LLWS will be possible in the PIA area and west tomorrow morning (11Z-14Z). Will include with the next update if likelihood increases. Knutsvig && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service North Platte NE
636 PM CDT Mon Mar 18 2024 .KEY MESSAGES... - Up and down temperatures through the week with unseasonable warmth Tuesday and Thursday and mild temperatures Wednesday and Friday. - A quick moving system will bring a chance (20 to 30%) of light rain or a rain-snow mix Thursday night into Friday morning across northern and north central Nebraska. Little to no accumulations expected. - Much cooler and unsettled conditions settle in this weekend with temperatures falling well-below normal into the 30s by next Monday. - A strong storm system is anticipated to impact the Plains region this weekend into early next week. Though this system may be our next shot at widespread precipitation of rain and snow across the area, confidence remains far too low to determine severity of impacts. Those with travel plans this weekend into early next week will want to continue to monitor the forecast for the most up to date information. && .SYNOPSIS... Issued at 400 PM CDT Mon Mar 18 2024 Recent GOES-16 WV imagery and RAP 500-mb analysis showed a blocking pattern across the CONUS. The stubborn meandering closed low pressure system continues to spin over the Desert Southwest. Just to the north of this feature, upper-level high pressure was centered over the Great Basin/Pacific Northwest with a ridge extending northwest into far northern British Columbia/Alberta. Further east of this feature, an upper-level shortwave trough over the middle Mississippi Valley was digging southward into the base of a larger- scale trough. All of these features combined has resulted in northwesterly flow aloft across western and north central Nebraska. At the surface, low pressure was deepening over Manitoba with an attendant cold front draped west-southwest across central Canada and a warm front extending south into the northern Plains, bisecting the Nebraska Panhandle. High pressure was holding strong over the central Plains which has resulted in clear skies, warming temperatures, and lighter winds as compared to yesterday. At 4 PM CT, temperatures ranged from 42 degrees at O`Neill to 58 degrees at Imperial, Ogallala, and Gordon. && .SHORT TERM /THROUGH WEDNESDAY/... Issued at 400 PM CDT Mon Mar 18 2024 Tonight... Quiet conditions and clear skies prevail overnight with warm air advection (WAA) increasing across the area. This will result in above normal temperatures in the 30s across western and north central Nebraska which will be +15 to 20F as compared to this morning`s low temperatures which ranged from 8 to 18 degrees. Tuesday and Tuesday night...As we head into daybreak on Tuesday, the surface low pressure system will be over the Great Lakes with an attendant cold front draped near the South Dakota/Nebraska border, clearing the area through the day. Despite cold air advection (CAA) in the wake of the passing front, temperatures will warm into the 60s across the area as the coldest air remains to the northeast of the area. Elevated fire weather conditions will be possible as a very dry air mass remains in place, primarily across southwest Nebraska (Fire Zones 210 and 209). However, wind gusts of 20 miles per hour or less will lessen overall fire concerns for Tuesday. Overnight lows on Tuesday will fall into the 20s across northern Nebraska to the mid 30s across south west Nebraska. Wednesday... From our up and down temperatures over the last few days, temperatures will be on the downward trend again on Wednesday, especially for the eastern half of the state. High temperatures ranging from the 40s across northeastern and north central Nebraska to 60 degrees across far southwest Nebraska. This fluctuation in temperatures will be felt again as we head into Thursday where highs soar back into the above normal range. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... Issued at 400 PM CDT Mon Mar 18 2024 On Thursday, west/northwest flow aloft will continue across western and north central Nebraska downstream of the upper-level ridge across the western CONUS. The upper-level low currently across the Desert Southwest finally gets its move on across the southern Plains with the approach of an upper-level low over the Pacific Northwest. Thursday will be the warmest day across the local area, though short- lived as much colder air settles in this weekend into early next week. Highs on Thursday will climb into the 60s for much of the area with southwest Nebraska breaking the 70 degree mark. The first of several disturbances to trek across the region through the long term period is expected Thursday evening into Friday bringing a chance (20 to 30%) of precipitation to northern and north central Nebraska. Temperatures will begin to fall into the mid 30s at the onset of precipitation, supporting a brief window for rain showers. However, with overnight lows quickly falling into the low 20s across northern Nebraska, expect a transition to rain-snow mix or snow showers. Anticipate any precipitation to come to an end around daybreak as the system quickly exits to the southeast. Little to no accumulations are anticipated which is highlighted by NBM probabilities for >0.1" of QPF indicating a 20% or lower. The upper-level ridge across the western CONUS will remain in place Friday, shifting eastward across the central CONUS Saturday as the upper-level trough begins to advance and dig deeper into the coast of the Pacific Northwest. Beyond this, considerable differences amongst model solutions exists on the overall evolution of how this troughing develops further eastward Sunday into early next week. One feature that has been consistently shown is that deep surface cyclogenesis occurs across the Plains Sunday into Monday. The main focus in the long term period surrounds the next major system expected to arrive this weekend into early next week. The upper-level trough begins to advance and dig deeper into the coast of the Pacific Northwest on Saturday. Beyond this, considerable differences amongst model solutions exists on the overall evolution of how this troughing develops further eastward Sunday into early next week. One feature that has been consistently shown is that deep surface cyclogenesis occurs across the Plains Sunday into Monday. Ensemble and deterministic model solutions continue to suggest a period of widespread precipitation across the forecast area, some snow appearing likely as well. The ECMWF Extreme Forecast Index (EFI) has just begun to show a signal of a potentially anomalous event across the region this weekend into early next week, though location continues to change with each run. Of note however is the Weather Prediction Center`s (WPC) Probabilistic Winter Storm Severity Index (WSSI-P) increasing across the region with a widespread 30 to 50% probabilities of minor winter impacts across the forecast area with 5 to 10% of moderate impacts, primarily across northern Nebraska. This system remains dynamic and will continue to monitor for trends as models get a better handle on the upper-level trough as it becomes established. Those with travel plans this weekend into early next week should make sure to check future forecasts as the details become more certain. && .AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/... Issued at 635 PM CDT Mon Mar 18 2024 VFR conditions will prevail over western and north central Nebraska tonight through tomorrow evening. Skies are expected to remain clear, with few passing high clouds. Surface winds will shift from westerly to northerly through the afternoon and evening tomorrow. A potential aviation concern tonight will be the low level jet across portions of north central Nebraska. While the primary LLWS concerns appear to be further east, along a line from Butte to Burwell, winds around 2,000 feet AGL should remain around 30 kts out of the west, with calmer surface winds as the boundary layer decouples across north central Nebraska tonight. Will continue to monitor the location ans strength of the low level jet this evening and tonight, but for now will leave LLWS out of the TAFs. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Viken SHORT TERM...Viken LONG TERM...Viken AVIATION...Richie
Area Forecast Discussion
National Weather Service Phoenix AZ
519 PM MST Mon Mar 18 2024 .UPDATE...Updated 00Z Aviation Discussion. && .SYNOPSIS... Unsettled weather continues with showers and thunderstorms expected through the remainder of this afternoon and early evening across south-central Arizona. Coverage of showers and thunderstorms decreases for Tuesday before the responsible weather system finally exits the region Wednesday. Ridging will build over the Intermountain West by the end of the week which will result in dry and tranquil conditions along with continued temperature increases towards well-above normal levels. Cooler unsettled weather then looks to return this weekend into early next week. && .DISCUSSION... An active afternoon is underway as showers and thunderstorms continue to develop across parts of central Arizona with strong winds, hail, locally heavy rainfall, and frequent lightning possible through the afternoon. The threat for strong and perhaps isolated severe thunderstorms will continue through the remainder of the afternoon into the early evening. The unsettled weather pattern continues as a Rex Block remains in place over the western CONUS with a cutoff upper-level low situated over the Southwest. Currently this afternoon, satellite WV imagery shows this upper low continuing to retrograde westward with the low center now situated over Riverside County. As a result, an influx of better moisture has creeped into south-central Arizona with PWAT values increasing upwards of 0.6-0.7" through the afternoon. Instability across the region continues to increase this afternoon with the latest SPC mesoanalysis showing SBCAPE values in excess of 500 J/kg and steep mid-level lapse rates around 8 C/km across Maricopa, Pinal, and Gila Counties. Combined with forced ascent associated with the aforementioned upper low, thunderstorms will continue to blossom across parts of south- central Arizona through the afternoon. The latest 12Z HREF keeps the bulk of this thunderstorm activity east of Phoenix through the afternoon with chances decreasing westward over the desert floor. However with the potential for strong outflows pushing across the valley floor this afternoon into the early evening, we could conceivably see some additional development make it into the Valley. As mentioned, strong outflows will be possible today with model soundings showing DCAPE values upwards of 700-900 J/kg this afternoon. HREF shows probabilities of exceeding 35 mph climbing upwards of 50-70% with the greatest chances residing across eastern Maricopa and Pinal Counties and portions of southern Gila County. Could see an isolated severe thunderstorm gust, which the HRRR has been aggressive in showing in some of its runs. Additionally, the better lapse rates and instability could lead to some larger hail compared to the small pea-sized hail that`s been more common in some of our recent events. In terms of dust, some areas of blowing dust generated by strong outflows will be possible, though less favorable given the expected orientation of outflow boundaries. Rainfall amounts outside of thunderstorms will generally remain light, mostly under 0.25" with locally heavy amounts for areas that end up under a thunderstorm. The upper low will shift eastward back over Arizona Tuesday while gradually weakening in the process. Instability will not be as high as today with SBCAPE values around 100-300 J/kg closer to the cold core. CAMs support isolated to scattered showers and thunderstorms developing tomorrow afternoon around the Kofas and over high terrain areas north and east of Phoenix. The Rex Block pattern finally breaks down heading into Wednesday and the upper low shifts east into New Mexico. This will be replaced with flat ridging over the Desert Southwest giving us drier, warmer weather for the latter half of this week. Temperatures by Thursday warm up into the low to mid 80s across the south-central Arizona lower deserts and mid to upper 80s across southeast California and southwest Arizona. Some areas will flirt with their first 90 degree temperature of the year on Thursday with NBM probabilities of reaching or exceeding 90 degrees climbing upwards of 50-70% across the Imperial Valley. Global ensembles then show troughing returning to the western CONUS this weekend into early next week. Thus, we will be looking at the return of some cooler unsettled weather once again. && .AVIATION...Updated at 0015Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Scattered showers and thunderstorms are currently moving through eastern and northern portions of the Phoenix Metro. These storms are anticipated to fall apart and exit the Phoenix Metro between 02-03Z. In the meantime, theses storms, along with their outflows, are causing easterly gusts around 20-25 kt with occasional gusts of 20-30 kt. Once these storms fall apart and exit the Metro, the winds will also start to calm, although some gusts to around 15-20 kt may hang on through 04-05Z, mainly for the northern terminals (KDVT & KSDL). Winds are expected to go light, aob 5 kt, and variable for the overnight hours, however they may predominantly be out of the east. By mid-morning the winds will become easterly before doing their typical diurnal switch to the westerly tomorrow afternoon. SCT-OVC cloud bases are currently around 6-8 kft with these showers and storms. Once they fall apart and exit the Metro, clouds will scatter out and start to lift with FEW-SCT high clouds expected for the overnight hours. Then FEW clouds with bases aoa 7-9 kft are expected for tomorrow afternoon. Southeast California/Southwest Arizona including KIPL and KBLH: No major aviation weather concerns are expected through the forecast period. Light and variable winds at KBLH will become northwesterly late this evening and then transition to northeasterly late tomorrow morning. At KIPL, current light westerly winds will become northwesterly late tomorrow morning. Wind speeds at both terminals will be aob 5 kt through the TAF period. FEW-SCT high clouds are anticipated through the TAF period. With FEW CU clouds developing tomorrow afternoon with bases aoa 8 kft. && .FIRE WEATHER... Low pressure will continue to promote rain chances over the next few days, especially across higher elevation locations. Outside of any rainfall activity, breezy conditions are expected across the the far eastern districts with max gusts approaching 30-35 mph at times. Elsewhere, winds should generally be light, with occasional afternoon breeziness. High pressure will then build over the region by the middle of the week resulting in drier and more tranquil conditions. MinRHs for the front half of the week should remain above 20-25% across the region before moisture levels begin to drop off once the aforementioned high pressure sets in. Temperatures will hover around normal for the next few days before a quick warm-up takes place during the latter portion of the week && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Smith AVIATION...Berislavich FIRE WEATHER...RW
Area Forecast Discussion
National Weather Service Las Vegas NV
745 PM PDT Mon Mar 18 2024 .SYNOPSIS...Broad upper low over the region will keep chances of afternoon showers through Tuesday evening across the Mojave Desert. As this low pressure pushes east midweek, conditions will dry out and temperatures will warm above seasonal averages. Another broad area of low pressure will impact the region next weekend with the return gusty winds, chances of precipitation and cooler temperatures. && .UPDATE...Mesoanalysis late this afternoon showed a cold core upper level low situated over southeast California, which allowed for weak instability to develop along with continued cyclonic flow aloft associated with waves of better energy in the vorticity fields. This resulted in scattered showers and thunderstorms developing, mainly in southern Mohave County and south of the I-15 in Clark and San Bernardino counties. Surface CAPE was able to climb to around 1000 K/Jg in parts of Mohave County where the most widespread precipitation and impacts occurred. Occasionally heavy rain and small hail were reported with some of the more organized thunderstorms around Kingman, AZ as webcam images and spotters reported isolated ponding on area roadways and nickle size hail. Rain gages reported up to 0.50 inches of rain over the past 6 hours in this region. Further north and west, precipitation was driven more by forcing and thus precipitation was not as robust. That being said, gusty outflow winds were able to develop in this region as sunny skies allowed for the low levels to warm up and dry out slightly compared to the past few days. A few locations reported outflow gusts of 30 to 40 MPH in southern Clark County and the Colorado River Valley. Outside of these areas, it was dry with mostly sunny skies. Instability has begun to weaken and radar has started to diminish in terms of lightning and activity, as expected. However much like the past few nights, continued waves of forcing moving east to west may result in isolated showers through the rest of the night. Updated precipitation chances to reflect this trend, trying to tie showery activity to where the better forcing should be. Isolated showers may persist through the night in southern Clark and southeast San Bernardino counties. Not expecting impacts from these showers as they should be fast moving and bring only light rain amounts. A stray lightning strike is not out of the question, as suggested by the latest HRRR, but again- not expecting widespread thunderstorm impacts. Overnight, most areas will be dry and any precipitation that may move through will be light and short lived. Winds will continue to diminish as well the rest of the evening. Light winds and low temperatures slightly warmer than last night can be expected. -Nickerson- && .PREVIOUS DISCUSSION...253 PM PDT Mon Mar 18 2024 .DISCUSSION...A compact vort center over southeast California will continue to drift south-southwest into northern Baja Mexico. The feature will still be capable of producing showers and thunderstorms as far north as the Morongo Basin into this evening. Elsewhere, radar detecting isolated showers over the Coconino Plateau, east of Mohave County. SBCAPE values of 500 J/kg being shown off the latest SPC mesoscale analysis has been expanding over central Mohave County over the past few hours. This area should fill in with showers and isolated thunderstorms this afternoon. The HRRR does show some of those showers and thunderstorms making it as far west as Clark and eastern San Bernardino later this afternoon and evening. Isolated showers possible overnight in parts of Mohave, Clark, and San Bernardino Counties as models show additional vorticity centers moving over the region as the cutoff low stays stationary near Yuma. The cutoff low is finally progged to start moving east into central Arizona Tuesday. However, lingering cyclonic flow and cold temperatures aloft will provide another day of pop-up showers and isolated thunderstorms mostly over Mohave County. But, can not rule out a few as far west as Clark and San Bernardino Counties. Dry and warmer weather returns to the region Wednesday-Friday under a broad ridge of high pressure. Warmest temperatures of the year so far expected. NBM currently has about a 40% chance that Harry Reid International Airport will hit 80 degrees either Thursday or Friday. Ensemble solutions showing a broad trough developing across the western CONUS over the weekend into early next week. Main impact looks to be strengthening south-southwest winds across the Mojave Desert/far southern Nevada and northwest Arizona. Will also need to keep a close eye on downslope potential in the lee of the southern Sierra in Inyo County, and potentially the Spring Mountains. Chances for precipitation begin to increase Friday night in western Inyo County, eventually spreading east through parts of south central Nevada Saturday. Depending on the eventual depth of the trough precipitation chances should increase as far south as the mountains of Clark and northern Mohave Counties. Temperatures slated to retreat back closer to normal Saturday, then below normal Sunday and Monday. && .AVIATION...For Harry Reid...Breezy northeast winds this afternoon with gusts around 20-25 knots anticipated. Wind direction expected to remain between 030 and 060. In the late afternoon, showers are expected to develop in the airport vicinity, with best chances to the south and east. If any precip reaches the airport (10% chance), it`s expected to be light. However, outflow from vicinity precipitation should turn winds more easterly. East breezes and vicinity showers linger through ~04z, possibly later, before drier conditions prevail and typical southwest winds resume. East- northeast winds return tomorrow, but much lighter than today. FEW- SCT mid-level clouds persist through the TAF period, with bases generally aoa 8kft. For the rest of southern Nevada, northwest Arizona and southeast California...Breezy northeast winds across most of the area today with gusts around 20-25 knots. Winds weaken this evening and overnight to less than 10 knots. Vicinity showers are possible at sites in the Las Vegas Valley and Colorado River Valley, with the best chance of precipitation at KIFP. Outflow from showers may produce erratic, gusty conditions at KIFP and potentially KEED as well. Cloud bases generally aoa 8kft. At KBIH, light and variable winds today becoming northerly tonight. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ DISCUSSION...Pierce AVIATION...Woods For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter