Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/21/24


Area Forecast Discussion
National Weather Service Cheyenne WY
529 PM MDT Sat Apr 20 2024 .KEY MESSAGES... - Freezing fog and light to moderate snowfall will be the main concerns through mid-afternoon across the South Laramie Range, Cheyenne Ridge, and southern Nebraska panhandle. Minimal snow accumulation expected, mainly on grassy and elevated surfaces. Roadways may be slick, especially bridges and overpasses. - Warming back up to near-normal, mild temperatures Sunday through Thursday along with a chance of late day showers and thunderstorms for Wednesday and Thursday. - Cooler and more unsettled weather is likely for Friday and Saturday. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 216 PM MDT Sat Apr 20 2024 While light snow and areas of dense fog continue from the I-80 Summit through the southern Nebraska panhandle, conditions are expected to begin clearing later this afternoon. However, these areas will still likely not see the sun today as the low clouds are expected to stick around through this evening and overnight. Areas of fog may return later tonight through early tomorrow morning across these same areas as easterly, upslope flow and low-level moisture stick around until they are pushed out by the incoming ridge. Once the winds turn westerly, the fog will likely dissipate quite quickly due to drier air moving in and downslope winds warming and further drying the air. Latest hires guidance overall shows surface winds starting to turn westerly sometime between 08Z and 12Z. Looking at soundings, the HRRR pushes the fog out the quickest, and has arguably been known to push fog/low-level moisture out too quickly, the NAM Nest holds onto it until well into the afternoon. But, the NAM Nest tends to not handle boundary layer moisture very well for this area. That being said, the reality will likely be somewhere in the middle with fog settling back in late tonight and continuing until early to mid-morning Sunday with some areas along the Cheyenne Ridge holding onto it longer than others. As the warmer air moves into southeast Wyoming and western Nebraska Sunday, afternoon high temperatures are forecast to be in the upper 50s to 60s with the cooler temperatures being between Laramie and Sidney. Clear skies and mostly light winds are expected Sunday with minimal weather concerns once the fog clears. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 216 PM MDT Sat Apr 20 2024 Monday...Brisk northwest flow aloft will produce a breezy to windy day along and west of Interstate 25. Mild temperatures once again with 700 mb temperatures near 5 Celsius. Tuesday...Slightly cooler at most locations in the wake of a weak cold frontal passage under northwest flow aloft. Wednesday...Ridging aloft builds across the region which will produce a decent warming trend as 700 mb temperatures rise to near 7 Celsius, yielding maximum temperatures in the upper 60s and lower 70s. Looks like there may be enough low and mid level moisture combined with easterly upslope winds to spark isolated to scattered afternoon showers and thunderstorms. Thursday...The next progressive shortwave trough aloft moves across Wyoming and Colorado, helping to produce scattered afternoon and evening showers and thunderstorms. Continued relatively mild based on the projected 700 mb temperatures. Friday...Cooler and more unsettled weather expected with adequate low and mid level moisture, and low level convergence along a cold front. Saturday...Cool and unsettled weather looks to continue as a series of shortwave troughs aloft move overhead under southwest flow aloft. Scattered showers and a few thunderstorms again possible based on instability parameters. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 523 PM MDT Sat Apr 20 2024 Surface high pressure and localized upslope will continue the low clouds and possible fog overnight for far southeast Wyoming and the southern Nebraska Panhandle, then a passing weather disturbance will clear out the low clouds Sunday morning. Wyoming TAFS...For Rawlins and Laramie, scattered to broken clouds from 6000 to 15000 feet will occur early this evening, then skies will be clear. Winds will gust to 26 knots at Rawlins after 15Z Sunday. For Cheyenne, ceilings will vary from 800 to 1500 feet until 12Z Sunday, with visibilities of one mile in fog from 06Z to 12Z, then skies will be clear after 12Z Sunday. Nebraska TAFS...For Chadron, Alliance and Scottsbluff, scattered to broken clouds from 3000 to 9000 feet will occur early this evening, then skies will be clear. For Sidney, ceilings will vary from 1100 to 2800 feet through 14Z Sunday, with visibilities of one mile in fog from 06Z to 14Z, then skies will be clear after 14Z Sunday. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...LEG LONG TERM...RUBIN AVIATION...RUBIN
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
324 PM PDT Sat Apr 20 2024 .SYNOPSIS...A dissipating cold front will bring a slight chance for drizzle to the North Coast through early this evening. Gusty northerly breezes are forecast to develop later tonight behind the front and then strengthen on Sunday. Otherwise, dry weather with above normal temperatures are forecast for Sunday and Monday. && .DISCUSSION...Visible satellite imagery showed a mass of thick clouds associated with a dissipating cold front just offshore the North Coast this afternoon. ARW and HRRR models continues to indicate potential (10-20% chance) for minuscule amounts (0.01-0.04in) of precip (drizzle) through early this evening. Breezy northerly winds will develop later tonight as the front moves to southeast. Otherwise, dry weather is forecast to continue for the remainder of the weekend into early next week. Interior temperatures will remain above normal (mid 70s to mid 80s) through Tuesday. Monday will most likely be the warmest day as offshore flow strengthens. Warmest interior valleys will likely (70-90% chance) peak in the low to mid 80s on Monday. Breezy to windy conditions are expected for coastal areas on Sunday as a cold air surge develops offshore in the wake of the front. Peak gusts (mostly in the late afternoon and early evening) of 25 to 35 mph are forecast. Granted, higher gusts (40-50 mph) are probable (>70% chance) for wind prone locations; the King Range, coastal headlands of SW Humboldt and windy point or Pt St George, On Tuesday, a 500mb shortwave trough will approach the Pac NW. Deterministic model guidance continues to indicate increasing buoyant energy and instability for possible (20-30% chance) showers and thunderstorms across the interior - mostly Trinity County - on Tuesday. Also, a closed cyclonic circulation evident at 925mb will likely induce a southerly wind reversal and a push of marine air/low clouds from the SW Monday night into Tue morning. Some cooling is expected on Tue, but high temps will likely (>60% chance) remain above normal (lower to mid 70s) until the air mass cools down more drastically toward the end of the week. Potential for precipitation will increase mid to late next week as a colder 500mb trough (temps <-25C). Timing has tightened up to Thu-Fri with 24 hours probabilities for > 1 inch in 24 hours for the western slopes of Del Norte and northern Humboldt Counties around 20 to 30%. There is still a great deal of variability with timing and precip amounts. Also, there are indications for a secondary trough in the NW flow on the backside of the main trough that may spark up more showers Friday night into Saturday (10-20% chance). It is more certain that interior high temperatures will cool down by late week - mostly in the 60`s. If snow levels fall to 5000 feet on Friday, high temps will struggle to reach the lower 40s in the high mountains Fri-Sat. Precipitation amounts are forecast to be light, but this time of year even light amounts will have impacts on outdoor plans or activities. Stay tuned. DB/ZVS && .AVIATION...Latest space pictures show mid cloud spreading over the Redwood Coast this afternoon ahead of a weak frontal passage. Some drizzle is expected with this front, and periods of IFR are possible later this afternoon as it passes overhead. Space pictures also show rapid clearing and subsidence in the cold sector behind the boundary. Thus any low cloud associated with this feature that moves onshore this afternoon and evening should mix out overnight, accompanied by developing NW winds. Otherwise, VFR conditions are expected across the interior. TDJ && .MARINE...Northwesterly wind will build through the waters from north to south with gusts over 21 kts in the outer waters later this evening. Wind will continue to increase with gale force gusts throughout the outer waters during the day on Sunday. These reach the inners this evening, and gale force gusts should still be expected right along shore around Cape Mendocino and Pt. St. George. Strong winds will build steep short period seas in excess of 10 feet by Sunday afternoon. Weak high pressure building over California will help gradually shunt the strongest wind offshore starting Monday, which will allow at least coastal conditions to gradually calm early this week. Short period waves dominate the sea state through early week, with a mid period swell up to 5 feet building Sunday. TDJ && .EKA WATCHES/WARNINGS/ADVISORIES... CA... None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from midnight tonight to 9 PM PDT Sunday for PZZ450. Small Craft Advisory from 3 AM to 9 PM PDT Sunday for PZZ455. Small Craft Advisory from 9 PM this evening to 3 PM PDT Sunday for PZZ470. Gale Warning from 3 PM Sunday to 3 AM PDT Monday for PZZ470. Small Craft Advisory until 3 AM PDT Sunday for PZZ475. Gale Warning from 3 AM to 9 PM PDT Sunday for PZZ475. && $$ Visit us at https://www.weather.gov/eureka Follow us on Facebook and Twitter at: https://www.facebook.com/NWSEureka https://www.twitter.com/NWSEureka For forecast zone information see the forecast zone map online: https://www.weather.gov/images/eka/zonemap.png
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
520 PM MDT Sat Apr 20 2024 ...New AVIATION... .SYNOPSIS... Issued at 220 PM MDT Sat Apr 20 2024 Dry west flow aloft will dominate the weather for much of the new week ahead. Temperatures will remain well above normal, especially mid-week. Afternoon breezes will pop up, but for this time of the year, winds will remain tame. Our next weather of note appears to be next Saturday and Sunday, when a Pacific storm system will bring in strong winds and a chance of mountain showers. && .DISCUSSION... Issued at 220 PM MDT Sat Apr 20 2024 For the most part, a quiet week ahead as zonal flow holds court through about Wednesday. In the short term, dry-line moved about as far west as the Cont Divide, but is already mixing out back to Deming. HRRR shows this mixing/drifting east will make it to western Sierra and Dona Ana Counties this evening before proceeding back west to around the Arizona line late tonight. Moisture (dewpoints in the upper 30s/mid 40s) will be enough to form CU/TCU over the mountains through early this evening, but little else. Strong low level east flow pushed stratus/fog up into east slopes of our terrain along the eastern CWA. Expect this to continue overnight before dissipating Sunday. Aloft short wave is just about to exit the eastern CWA. Otherwise aforementioned zonal flow pretty clean through Wednesday. Previous model runs did show jet streak/short wave in sub-tropical jet moving east, just south of the CWA and possibly a risk of a shower for Hudspeth Co Sunday night. Latest models now show this feature a bit further south, more of a threat to the Big Bend than our southeastern CWA. Temperatures will remain well above normal. Near record highs possible Tuesday and Wednesday. Late week has the potential for some impactful weather. Merged Pacific low into the sub-tropical jet will move to Arizona Thursday morning and across northern New Mexico Thursday afternoon for a windy afternoon. Winds look to be sub advisory at this time. A second Pacific storm system drops in over the Great Basin Saturday with attendant increase in afternoon winds. Latest model suite has trended down slightly for Saturday winds, but could still be looking at advisory criteria winds. Upper low likely too far north for even most mountain showers, but the Gila/Black Range could still see a stray shower. && .AVIATION... (00Z TAFS) Issued at 514 PM MDT Sat Apr 20 2024 VFR conditions through the period with FEW100 SCT250, but dissipating aft 00-01Z. There will be low, east slope hugging stratus along the east slopes of the Sacramento Mtns...BKN- OVC010 with patchy 3SM BR, with mountain obscurations. Surface winds generally from the east/southeast 10-15 knots. && .FIRE WEATHER... Issued at 220 PM MDT Sat Apr 20 2024 Not much fire weather concerns early part of forecast with dry weather and just breezy afternoons through Wednesday. Winds start ramping up Thursday into the weekend and drive humidity down. Thursday will see a windy afternoon and then Saturday will be very windy in the afternoon. So we are looking at near-critical to Red Flag criteria days, mainly Thursday and Saturday. Min RH: Lowlands 18-30% Sunday and Monday decreasing to 8-13% Tuesday through the rest of the week. Mountains 25-40% Sunday and Monday decreasing to 10-20% Tuesday through the rest of the week. Vent rates fair-good Sunday and Monday improving to excellent Tuesday through Saturday. && .PRELIMINARY POINT TEMPS/POPS... El Paso 50 77 50 84 / 0 0 0 0 Sierra Blanca 43 67 43 76 / 0 0 10 10 Las Cruces 47 78 47 82 / 0 0 0 0 Alamogordo 43 75 43 80 / 10 0 0 0 Cloudcroft 34 54 32 58 / 10 10 0 10 Truth or Consequences 48 76 49 81 / 0 0 0 0 Silver City 46 72 44 75 / 0 0 0 0 Deming 46 79 46 82 / 0 0 0 0 Lordsburg 46 79 50 83 / 0 0 0 0 West El Paso Metro 49 75 48 82 / 0 0 0 0 Dell City 41 68 40 81 / 0 0 0 0 Fort Hancock 44 76 45 84 / 0 0 10 10 Loma Linda 43 67 41 75 / 0 0 0 0 Fabens 46 78 47 84 / 0 0 0 0 Santa Teresa 45 75 45 82 / 0 0 0 0 White Sands HQ 49 75 48 81 / 0 0 0 0 Jornada Range 43 76 41 80 / 0 0 0 0 Hatch 44 79 44 83 / 0 0 0 0 Columbus 47 79 49 82 / 0 0 0 0 Orogrande 44 72 43 79 / 0 0 0 0 Mayhill 35 60 34 72 / 10 0 0 10 Mescalero 37 65 36 69 / 20 0 0 10 Timberon 34 62 32 68 / 0 0 0 0 Winston 42 71 41 74 / 0 0 0 0 Hillsboro 44 76 42 79 / 0 0 0 0 Spaceport 43 77 42 79 / 0 0 0 0 Lake Roberts 42 74 40 76 / 0 0 0 10 Hurley 42 74 41 78 / 0 0 0 0 Cliff 36 82 38 83 / 0 0 0 0 Mule Creek 33 78 35 79 / 0 0 0 0 Faywood 45 73 42 76 / 0 0 0 0 Animas 45 80 49 84 / 0 0 0 0 Hachita 45 79 48 82 / 0 0 0 0 Antelope Wells 46 79 48 84 / 0 0 0 0 Cloverdale 50 77 48 79 / 0 0 0 0 && .EPZ WATCHES/WARNINGS/ADVISORIES... TX...None. NM...None. && $$ FORECASTER...14-Bird
Area Forecast Discussion
National Weather Service Peachtree City GA
1055 PM EDT Sat Apr 20 2024 ...Evening Update... .UPDATE... Issued at 1053 PM EDT Sat Apr 20 2024 Made some minor tweaks to precip chances over the next few hours based on overall radar trends. Otherwise, forecast remains on track. Some initial thunder possible with rain/storms pushing into area now, but not expecting any more severe weather overnight. Lusk && .SHORT TERM... (This afternoon through Sunday) Issued at 211 PM EDT Sat Apr 20 2024 Weak surface boundary is situated across south central Georgia this afternoon. The old boundary will remain nearly stationary through Sunday afternoon before shifting southward into northern Florida by the evening. High pressure begins to build in from the west overnight Sunday. The nearly stationary front will be the main focus for any precipitation development overnight and into the first half of Sunday. In addition, several strong shortwaves will move east in the flow, providing an excellent source of lift along with the convergence along the front. The best CAPE may be shunted to southern portions of the state, but there should be enough surface instability available for isold to scattered thunderstorms through Sunday afternoon, especially along and just south of the front. To the north of the boundary, widespread showers are most likely with some embedded thunder. Strong storms are possible, especially this afternoon across the southern third of the CWA. An isolated severe thunderstorm cannot be ruled out. The potential for severe weather should wane with the loss of heating, but isolated strong storms could be possible overnight/early Sunday - especially south of Macon to Columbus. Hail and gusty winds will be possible with any strong storms. With PWATs around 1.5" south of I-20, locally heavy rainfall will also be possible. There is some differences between the models on the overall evolution of the pops with this system. The HRRR performed fairly well in the short term period yesterday, so have trended this way for the afternoon. The ARW precip pattern looks more reasonable for overnight and the first half of Sunday and have trended close to it during this period. Drying/clearing is expected for late tomorrow afternoon into the overnight hours. Temps tomorrow will likely average around 10 to 20 degrees below normal for this time of year. Thick cloud cover and widespread rain will limit heating across much of the forecast area. A cooler and drier airmass will settle across north and central GA Sunday night. Mins should range from the mid 30s in the far NE mtns to around 50 in the SE. Will have to monitor the far NE portions of the state for frost potential. Winds may diminish, but there could be enough clouds around to prohibit good radiational cooling and keeping frost more patchy in nature.NListemaa && .LONG TERM... (Monday morning through next Friday) Issued at 211 PM EDT Sat Apr 20 2024 The bulk of the long term period will be fairly nondescript after the departure of Sunday`s rainfall. Surface high pressure will slide overhead from Monday into Tuesday, bringing sunny, dry, and cooler conditions. Monday will be the coolest day of the period with highs remaining in the 60s areawide, some 10+ degrees below normal. Tuesday morning lows will dip at least into the 40s areawide, with some upper 30s possible across far north Georgia as clear skies and calm winds maximize radiational cooling. A warming trend then begins from Tuesday into midweek as low level flow becomes southerly as the surface high shifts eastward. Still, Tuesday and Tuesday night will remain on the cool side, likely a few degrees below normal. A weak frontal boundary looks to dip into the area from Wednesday into Thursday, though the forecast remains dry given very little moisture in place. In fact, rain chances look to hold off until at least next weekend. Temperatures by next weekend also rebound, likely returning a few degrees above normal. RW && .AVIATION... (00Z TAFS) Issued at 805 PM EDT Sat Apr 20 2024 Wet forecast for most all TAF sites. Rain should move into metro sites by 03Z timeframe and become steady by the early morning hours, continuing into the early afternoon before tapering off by 19-21Z. Not expecting TS at this time at metro TAF sites. Cigs will dip through the overnight, becoming IFR by 09-10Z. IFR conditions expected to linger through morning and early afternoon before improving to MVFR by 19-20Z as rain begins to end. Winds will be NW at metro sites, 5-10 kts. Winds will be more VRB at AHN, MCN, and CSG. MCN and CSG will have lower overall rain chances, with PROB30 in place for tomorrow for SHRA. //ATL Confidence...00Z Update... Medium-high on morning cigs, high all others. Lusk && .PRELIMINARY POINT TEMPS/POPS... Athens 53 59 47 65 / 60 70 10 0 Atlanta 52 57 47 64 / 60 70 10 0 Blairsville 45 55 39 63 / 60 70 10 0 Cartersville 47 59 41 66 / 60 70 0 0 Columbus 56 61 48 69 / 60 50 10 0 Gainesville 52 59 46 64 / 60 70 10 0 Macon 59 62 50 67 / 60 40 10 10 Rome 49 62 43 66 / 70 70 0 0 Peachtree City 51 59 45 66 / 60 70 10 0 Vidalia 65 72 53 66 / 30 50 10 10 && .FFC WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...NListemaa LONG TERM....RW AVIATION...Lusk
Area Forecast Discussion
National Weather Service Green Bay WI
1014 PM CDT Sat Apr 20 2024 Updated aviation portion for 06Z TAF issuance .KEY MESSAGES... - Elevated fire weather conditions are likely Sunday and Monday during the afternoon and early evening hours due to relative humidities ranging from 20 to 30 percent and winds of 15 to 25 mph. - The next chance for precipitation is Monday evening through Tuesday. A few thunderstorms are possible Tuesday, but severe weather is not expected. && .DISCUSSION... Issued at 249 PM CDT Sat Apr 20 2024 Short Term...Tonight and Sunday Low level moisture remains locked in the region for the early afternoon hours, keeping low clouds in for at least the middle to late afternoon before incoming surface ridging begins to scour out the lingering cloud cover. As a result, lowered the afternoon high temperatures a few degrees. Tonight, surface ridging should fairly quickly bring an end to lingering low clouds from northwest to southeast, with clear skies across most of the region by the overnight hours. The only exception to this could be areas near the Upper Peninsula border, as satellite and water vapor trends do bring in some additional high clouds for tonight. Winds should decrease a bit from the afternoon but could remain breezy overnight, with a few gusts to around 10 to 15 mph at times. Overnight low temperatures remain in the upper 20s near the Upper Peninsula border to the lower 30s near east-central. Sunday, skies will be largely sunny through the day, which should allow for some warmer surface temperatures into the 50s and possibly lower 60s. Deep mixing through ~800-700mb will also mean another fairly breezy day in the afternoon and evening, and the potential for fairly low relative humidity values around 20 to 30 percent in the afternoon, which will create a period of elevated fire weather conditions. Long Term...Sunday Night Through Saturday The upper air pattern for next week is pretty typical for this time of the year, with a few significant weather systems coming by and temperatures not too far from seasonable averages. A surface high over the Midwest will allow for clear skies Sunday night, with temperatures falling below freezing thanks to dry air and light winds. Winds will become southwesterly Monday as the surface high moves east and a cold front approaches from the Plains. Forecast soundings from the RAP and Canadian models look best as far as mixing heights and surface dewpoints. That will make for elevated fire weather conditions Monday afternoon and early evening. Showers along the front will probably not arrive until the evening hours. A sharp upper trough will move across the area Tuesday. Cold temperatures aloft will make for showers and thunderstorms. It could be cold enough aloft for some graupel or snow showers in the far north. A surface high and upper ridge will follow and bring dry and cooler weather for Wednesday and Thursday. Milder weather is expected Thursday as southerly flow returns ahead of the next systems, which will bring showers and thunderstorms for Friday. && .AVIATION...for 06Z TAF Issuance Issued at 1007 PM CDT Sat Apr 20 2024 Stratocumulus clouds should be east of the region by issuance time, with only patchy mid/high clouds expected overnight. SCT- BKN high-based cumulus clouds are expected to form during the late morning and afternoon on Sunday, then dissipate in the evening. Light west winds are anticipated overnight, with gusty WNW winds picking up in the late morning and afternoon Sunday, before diminishing again around sunset. && .FIRE WEATHER... Issued at 249 PM CDT Sat Apr 20 2024 Moderating temperatures and a dry airmass will lead to elevated fire weather conditions on Sunday and Monday. Relative humidity will be low (20-30 percent in the sandy soil regions) both days, but winds look to be a little stronger on Monday. Another period of elevated fire weather conditions is possible next Wednesday and Thursday, as a dry airmass moves into the region. Ensembles indicate PWATs are forecast to be 20-40% of normal. Winds will likely be below critical levels due to the proximity of the prevailing high pressure system. && .GRB WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION.....Uhlmann/RDM AVIATION.......Kieckbusch FIRE WEATHER...Kieckbusch
Area Forecast Discussion
National Weather Service Indianapolis IN
919 PM EDT Sat Apr 20 2024 .KEY MESSAGES... - Becoming Mostly Cloudy tonight; Cold with Frost possible - Partly Cloudy and warmer on Sunday - Widespread frost possible Monday morning. - Increasing rain chances Tuesday, low chance for thunderstorms - Temperatures generally near seasonal next week, but brief cooldown is possible Wednesday into Thursday && .FORECAST UPDATE... Issued at 918 PM EDT Sat Apr 20 2024 GOES-16 IR satellite imagery, obs and Hi-Res soundings support raising cloud cover the rest of the evening especially. The increase in cloud cover along with winds expected to stay up to 5 knots or so should keep frost from being a big issue overnight. Raised overnight lows a degree or two based on the more pessimistic cloud cover. && .SHORT TERM (This evening through Sunday)... Issued at 243 PM EDT Sat Apr 20 2024 Synopsis: Surface analysis early this afternoon shows strong high pressure in place over eastern Montana, Western SD and western NB. A surface ridge extended southeast from the high, stretching across northern MO to SW Indiana and Central KY. Cool northwest surface flow was in place across Central Indiana, along with a moderate pressure gradient. Dew points were in the dry mid 20s. GOES16 shows clear skies in place across most of the forecast area. Some CU had developed across northern Indiana, and some high cloud was blowing off some convection over the southern plains, spilling into the Ohio Valley. Aloft, a deep area of low pressure was found east of Hudson Bay. This feature was providing a nearly zonal westerly flow in place aloft across Indiana and water vapor imagery showed only Pacific moisture aloft within that flow. Tonight... The mostly clear skies in place across Central Indiana today are expected to be lost to cloudiness this evening and overnight. Models suggest the upper flow becomes a bit southwesterly tonight. This will allow for the advection of mid and high cloud from the Central and southern plains to arrive across Central Indiana through the overnight hours. Furthermore, a weak upper trough rotating around the low is expected to push toward central Indiana providing some lift well aloft. HRRR suggests the arrival of high clouds in this manner, arriving this evening before exiting shortly after daybreak on Sunday. Forecast soundings also trend toward high cloud saturation with subsidence in place in the lower and middle levels. Meanwhile at the surface the strong ridging is expected to remain in place with cool air in place at the surface. Given our cool, dry air mass, lows in the middle 30s will be expected overnight with light winds. This would be an ideal setup fro frost, but with the expected cloud cover, frost may not form. Confidence on clouds is high, thus confidence for frost is low. Hence will issue an SPS for isolated frost overnight. Should the evening shift determine that the cloud cover will not come to pass, a frost advisory will likely be needed. Sunday... The weak upper trough axis is suggested to arrive and pass across Central Indiana on Sunday. This will quickly usher the mid and high cloud out of central Indiana by late morning and early afternoon as subsidence becomes predominate through the entire column. Again forecast soundings show drying within the column, with some late afternoon flat topped CU possible due to a mid level inversion when convective temperatures are reached. The lower levels will remain under the influence of the strong high pressure system over the southern plains, along with an associated ridge axis stretching across the Ohio Valley. There is some slight warm air advection in place on Sunday afternoon, thus slightly warmer highs in the middle 50s will be expected. && .LONG TERM (Sunday night through Saturday)... Issued at 243 PM EDT Sat Apr 20 2024 Sunday night through Monday... Quiet weather conditions will persist as surface high pressure and upper ridging is centered near the central CONUS. Expect one more cool night before warm air advection from the building ridge leads to a warm up early next week. Lows dropping into the 30s Monday morning combined with clear skies and light winds will likely lead to widespread frost development. Expect surface high pressure to then shift east on Monday allowing for return flow to warm temperatures into the 60s. Monday night onward... Rain chances return Tuesday as a shortwave trough and associated low pressure system move across the Great Lakes Region. Subsidence induced dry air still present across the Mid-South may lend to limit overall moisture return further north. Guidance shows a narrow corridor of sufficient moisture return and increasing dynamics from the approaching system to support rainfall. QPF amounts should remain light due to a lack of deeper moisture, likely under half an inch. Weak destabilization could also support a few PM thunderstorms. Expect the progressive pattern aloft to help push this system further east by Tuesday night resulting in drier conditions returning late. Cold air advection and surface high pressure building in behind the departing low will allow for quiet weather conditions to persist through much of Thursday before another system approaches late next week. Temperatures falling into the 30s Thursday morning leads to some frost concern, though at this time it appears winds may remain elevated enough to limit this potential. Models begin to diverge by late next week which limits forecast confidence, but there is a general signal for an active pattern to return. One thing to note, Indianapolis is already in the top 13 for wettest April`s on record. Numerous chances for rainfall Tuesday, and then again late next week into the weekend will likely push Indianapolis at least into the top 10 for wettest April`s on record. && .AVIATION (00Z TAF Issuance)... Issued at 642 PM EDT Sat Apr 20 2024 Impacts: - None Discussion: Dew points in the 20s and dry boundary layer per Hi-Res soundings lend high confidence to VFR flying conditions through the TAF period. Only cloud cover will be a brief diurnal cu deck to start at KLAF and mid and high clouds in the fast zonal flow aloft, ahead of a northern Plains trough. Winds will be northwest mostly less than 10 knots. && .IND WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...MK SHORT TERM...Puma LONG TERM...Melo AVIATION...MK
Area Forecast Discussion
National Weather Service North Platte NE
555 PM CDT Sat Apr 20 2024 .KEY MESSAGES... - Tonight could be the last night of freezing weather for the foreseeable future. - A strong storm system continues to be predicted to affect wrn and ncntl Nebraska Thursday and Friday. No severe weather hazards expected across the region at this time. && .SHORT TERM /THROUGH SUNDAY NIGHT/... Issued at 318 PM CDT Sat Apr 20 2024 The upper level disturbance affecting ern Colo/KS and swrn Nebraska with snow is expected to exit Nebraska early this evening. This timing is based a forecast blend using the HREF, HRRR, RAP and short term model blend. Thereafter, there is evidence of dry air moving in aloft and light winds near or below h850mb. The sfc high pressure across the nrn high Plains this afternoon will settle across wrn Nebraska by 12z Sunday morning. Patchy/areas of fog are in place across swrn Nebraska and the srn Panhandle for the prospect of dry air aloft and trapped moisture at the sfc. Given the aggressive nature of the high Plains sfc high pressure leading to widespread low temperatures in the 20s this morning, the temperature forecast tonight leans toward the cooler guidance blend and NBM 50th for lows in the 20s once again. The same strategy is in place Sunday for full sun and warming temperatures. This suggested highs in the upper 50s to lower 60s. The warmer short term model blend is in place Sunday night for lows in the upper 30s to lower 40s. This forecast is based on strong warm air advection associated with sfc low pressure circulating through the srn Canadian prairies. The blended wind forecast using the short term blend plus the NBM keeps winds up overnight and into Monday morning; the forecast assumes no decoupling and very modest radiational cooling. && .LONG TERM /MONDAY THROUGH SATURDAY/... Issued at 318 PM CDT Sat Apr 20 2024 The next rain chance is with the arrival of a cold front Monday night. The NAM and ECM support isolated to scattered showers and thunderstorms, mainly across srn/cntl Nebraska. The focus is the front and the forcing is an upper level disturbance dropping south through the Dakotas for this event. Moisture transport could be fleeting, directed toward ern Nebraska and WPC suggested no QPF for this forecast. POPs are limited to 30 percent for these reasons. The models are coming into better timing agreement for a strong storm system progged to affect wrn/ncntl Nebraska Thursday and Friday. Significant track differences remain ranging from SD in the GEM to KS/ern Neb in the GFS. The ECM is in the middle favoring nwrn and ncntl Nebraska. The sfc low could deepen below 990 mb in the GEM and ECM. Chance/likely POPs are in place beginning as early as Wednesday night when the region will be under the influence of strengthening southwesterlies aloft and increasing moisture advection at h850-700mb. It is worth noting rain/thunderstorm chances Wednesday night through Thursday night could be greatly limited by a strong cap, around 10C at 700mb, as shown by the ECM. The GFS shows this cap weaker, cooler than 10C. Regardless, both models show the cap weakening with wrap- around rain Friday which could last into Saturday if the models track the system slower. && .AVIATION /18Z TAFS THROUGH 18Z MONDAY/... Issued at 555 PM CDT Sat Apr 20 2024 VFR conditions expected at TAF sites through this valid period. Satellite imagery shows a bloom of cumulus/stratocumulus north of Hwy 2 that will gradually diminish with loss of daytime heating and push off to the south. However radar shows some very light SHRA/SHSN coincident with the main cloud shield south of Hwy 2. There clouds are also moving southward and expect KLBF will lose the CIG and become SCT this evening/early tonight with no impacts from any light precipitation. There is a hint for some fog across far southwest Nebraska late tonight, and while there may be some valley fog right over the river do not expect significant impacts on airfields so will not include with this TAF issuance. Winds will be light/variable tonight through Sunday morning. Once diurnal heating mixes the boundary layer Sunday afternoon, expect some gusts 20 to 25kt at KVTN but under 20kt at KLBF. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...MBS
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
920 PM CDT Sat Apr 20 2024 .KEY MESSAGES... - Freeze expected for areas west/southwest of Chicago late tonight/early Sunday morning. Frost likely elsewhere outside of Chicago. - A period of inclement weather with periods of showers and storms possible towards the end of next week into the weekend. && .UPDATE... Issued at 920 PM CDT Sat Apr 20 2024 Have elected to hoist a Frost Advisory for the remainder of the CWA not already in the Freeze Warning, save for central Cook County. Observational trends suggest that the overhead stratocumulus deck should clear out over most of the area by about 09-10Z, and recent HRRR runs have trended towards a little more boundary layer decoupling occurring, at least in our southern counties, which will be more closely positioned to the center of an incoming region of surface high pressure. Thus, confidence has increased enough in widespread frost developing in Ford, Iroquois, Kankakee, and southern Will counties to warrant the issuance of a Frost Advisory there. Farther to the north, some uncertainty remains regarding whether boundary layer decoupling will remain more limited, thus permitting at least occasional mechanical mixing into 10-15 kt flow atop the stabilizing boundary layer, which would tend to inhibit frost development. While the stratocumulus should clear out of there within the next 5-6 hours, the coverage and overall influence of some incoming high-level cloud cover remains somewhat uncertain, and it is possible that this also will end up being a limiting factor for frost development closer to the Illinois- Wisconsin state line. Our northwest Indiana counties will be dealing with these same wind and cloud cover-related uncertainties, plus the possibility that the lower stratocumulus clouds don`t depart in time for efficient radiational cooling to begin until just before dawn. In spite of these lingering uncertainties, opted to err on the side of caution and issue the Frost Advisory through pretty much the remainder of our CWA, as at least patchy frost will still probably develop in our wind- and cloud-beleaguered counties with temperatures still likely to fall into at least the mid 30s there overnight. The lone forecast zone that was left out of the Frost Advisory was central Cook County, with the expectation that the influence of the urban heat island effect will keep temperatures there just "warm" enough to preclude the development of widespread frost. Ogorek && .DISCUSSION... Issued at 231 PM CDT Sat Apr 20 2024 Through Sunday night: Northern IL/northwest IN remain within the southern periphery of a deep upper trough over eastern Canada. Breezy west- northwest flow was maintaining cold advection, with steep low- level lapse rates helping to produce a dense, widespread stratocu deck across the area this afternoon. Daytime temperatures have struggled in the face of this cold advection and opaque cloud cover, with readings only in the low-mid 40s across most of the cwa as of 2 pm. Clouds are expected to persist in this evening, though some thinning is likely with time as we lose the diurnal component. Timing of trailing edge over the upper Mississippi Valley per satellite imagery suggest clearing from the northwest by mid-evening for our northwest counties, and eventually around/a bit after midnight farther to the east (perhaps a bit earlier with the loss of diurnal low- level instability). Clearing, continued low-level cold advection and a weaker surface pressure gradient (and resulting winds) than last night suggest we`ll likely have freezing temperatures across the western half or so of the cwa by morning. In collaboration with MKX/DVN and ILX have elected to issue a Freeze warning for areas west and southwest of Chicago, where conditions appear most favorable. Farther east, will likely see some areas of frost toward morning, though air temperatures are expected to remain above freezing. Had contemplated a frost advisory, though lingering 10-15 kt flow above the boundary layer and slightly warmer temperatures lend lower confidence to longer duration widespread frost conditions. Better frost potential looks to be across central IL, where winds will be lighter in closer proximity to the surface ridge axis. Sunny skies are expected for Sunday, with weak mid-level ridging developing in the wake of an early morning positive-tilt mid-level short wave. Guidance depicts 50-60 meter mid-level height rises within deep subsidence behind this wave, with the pocket of coolest mid-level air also moving off to the east of the region. Under sunshine (perhaps just a shallow fair-weather cu field), temps should "rebound" to the upper 50s/around 60 degrees for afternoon highs. We`ll still be a bit breezy, north of the surface ridge, with west-northwest winds gusting around 20 mph during the day. Winds diminish and back west-southwest Sunday night under clear skies. Could see some patchy areas of frost away from the city again toward Monday morning, though overnight lows are expected to be a bit warmer ranging from the mid-30s to around 40 in Chicago as warm advection begins to strengthen aloft. Ratzer Monday through Saturday: Increasing low-level southwest flow behind a departing ridge combined with strong diurnal mixing into a rather dry layer above the PBL will support the potential of brush fire spread Monday afternoon. Afternoon fine fuel moisture values are already below 10% this afternoon, so with additional drying the next couple days, current forecast RH values as low as 25-30% and wind gusts possibly over 20 mph, we will continue to message elevated fire wx concerns. Strong upper-level diffluence ahead of a zonal jet streak over the northern Great Plains will promote decent mid-level ascent over an antecedent dry airmass. Modest mid-level lapse rates around 7.5C/km should foster scattered high-based showers or even a storm or two late Monday night. The surface low associated with the upper jet streak and concomitant mid-level trough/low will push a surface front across the CWA sometime Tuesday afternoon. Deep mixing and marginally favorable low- level moisture profiles should support diurnally driven showers and some thunderstorms along/ahead of the front. More aggressive guidance even suggests the potential for small hail given freezing levels as low as 6kft and steep lapse rates into the hail growth zone below EL values around 20kft. In the wake of Tuesday`s system, a ~1030hPa high will settle southeastward across the Great Lakes region Wednesday through Thursday. With another dry and cool airmass in place during this period and the southwest extent of the high edging into the forecast area, widespread frost conditions and/or sub-freezing temperatures are possible Wednesday night. A highly amplified mid-level pattern Friday into next week will bring another period of active weather to the central portion of the CONUS. While consensus guidance favors keeping a seasonably strong low well northwest of the forecast area, several members (including the deterministic GFS) are precariously close enough to warrant close monitoring of trends for stronger convection in our area late Friday. Kluber && .AVIATION /00Z TAFS THROUGH 06Z SUNDAY/... Issued at 627 PM CDT Sat Apr 20 2024 There are no significant aviation forecast concerns for the current TAF period. The overhead VFR stratocumulus deck is expected to disperse later tonight, yielding clear to mostly clear skies for tomorrow. Winds should remain out of the west or west-northwest throughout the TAF period while staying near or under 10 kts throughout this time, though some gusts closer to 20 kts are possible at times tomorrow afternoon. A lake breeze may also affect GYY tomorrow afternoon, but confidence in this occurring is currently too low to warrant adding a new line to the GYY TAF for that with this issuance. Ogorek && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Freeze Warning from 3 AM to 8 AM CDT Sunday for ILZ003-ILZ004- ILZ005-ILZ008-ILZ010-ILZ011-ILZ012-ILZ019-ILZ020-ILZ021- ILZ032. Frost Advisory from 3 AM to 8 AM CDT Sunday for ILZ006-ILZ013- ILZ023-ILZ033-ILZ039-ILZ103-ILZ105-ILZ106-ILZ107-ILZ108. IN...Frost Advisory from 3 AM CDT /4 AM EDT/ to 8 AM CDT /9 AM EDT/ Sunday for INZ001-INZ002-INZ010-INZ011-INZ019. LM...None. && $$ Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Memphis TN
946 PM CDT Sat Apr 20 2024 ...New UPDATE... .UPDATE... Issued at 937 PM CDT Sat Apr 20 2024 Minor adjustments were made to overnight PoPs as this first round of rain comes to a close. As another weak shortwave trough moves through the area, a second round of showers is expected to surge up through the ArkLaMiss overnight tonight. Moisture nor instability look sufficient enough to produce anything but light scattered showers through sunrise with less than a tenth of an inch of QPF. Once the sun rises tomorrow, dry conditions will return and remain in place for much of the week. && .SYNOPSIS... Issued at 140 PM CDT Sat Apr 20 2024 Cool temperatures are the biggest story weather-wise over the next seven days. Monday should be the coolest morning featuring low temperatures in the middle 30s to low 40s. Frost is possible in portions of west Tennessee, mainly near the Tennessee River. Otherwise, gradual warming is expected tomorrow(Sunday) afternoon through Midweek along with gradually warming temperatures. High temperatures should approach 80 degrees by Friday. && .DISCUSSION... (This evening through next Friday) Issued at 140 PM CDT Sat Apr 20 2024 Zonal flow is in place across the middle and lower Mississippi River Valley. Weak impulses moving through the westerly flow will result in another round of elevated showers and possibly a few thunderstorms this afternoon, mainly in north Mississippi. The HRRR is a bit of an outlier shifting most of the precip into Alabama well before midnight. That may be a bit optimistic based on current radar. Showers and thunderstorms stretch as far west as the Texas Panhandle. However, high pressure should build into the Midsouth from the northwest tonight and should shift the storm track farther south. Confidence is higher that rain will continue through much of the night, shifting out of the region before sunrise. Sunday should be mostly dry, especially after midday with dry conditions continuing through midweek. Cool conditions are expected tonight and Monday morning with frost possible near the Tennessee River Monday morning. Most of the Midsouth will be in the middle to upper 30s. High temperatures should be in the low to middle 60s tomorrow and in the middle to upper 60s Monday. A positively tilted trough will swing across the Mississippi River Valley early Monday and surface high pressure should shift east of the area Monday afternoon. This will mark the beginning of a gradual warming trend next week. High temperatures should be in the middle 70s by Wednesday and near 80 degrees by Friday. A ridge will build over the eastern Rockies and Plains after midweek setting up northwest flow across the Midsouth. However, guidance is in poor agreement during this time frame. For now we will carry low pops Thursday into Friday and and see how things develop in subsequent model runs before increasing or removing PoPs late in the work week. 30/Sirmon && .AVIATION... (00Z TAFS) Issued at 636 PM CDT Sat Apr 20 2024 An area of rain will push across TUP over the next couple of hours otrw VFR conds will prevail throughout the period. A few more SHRAs are possible south of I-40 later tonight but aviation impacts will be limited. NNE winds at 8-10 kts will increase to 10-14 kts early Sunday morning with gusts 16-22 kts. && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$ PUBLIC FORECAST...JDS AVIATION...SJM