Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/20/22

Area Forecast Discussion
National Weather Service La Crosse WI
1000 PM CST Sat Nov 19 2022 .DISCUSSION...(This evening through Saturday) Issued at 213 PM CST Sat Nov 19 2022 Key Messages: - Remaining cold through Sunday - Potential for some precipitation Thanksgiving into Friday Tonight and Sunday... Arctic air mass continues sagging southeast with the upper level trough evident on satellite water vapor imagery. With the cracking cold air advection, low level lapse rates steepened providing slight instability and some heavier bouts of snowfall rates temporarily traversed the area this morning. Now that low level CAA has weakened, upstream conditions suggest lighter snowfall rates within scattered snow showers into tonight. Temperatures in the teens extend from western Wisconsin into central Minnesota. Slight clearing overnight will allow temperatures to reach the single digits area wide. While wind gusts wane overnight, wind chill temperatures still expected to be below zero area wide. A meager low level trough will scoot by Sunday morning, providing precipitation chances primarily in central Wisconsin. Have increased PoPs in Clark & Taylor counties, with HRRR (19.12Z) and RAP (19.15Z) soundings showing a seriously stout dendritic growth zone. Snow will be transient, lasting only a couple hours, but given the potential for such a thick DGZ with mid level warming, something to keep an eye on. With short term model consensus lacking, HREF (19.12Z) highest confidence for at least 0.1". Winds remain increased primarily west of the Mississippi River during the day Sunday with highest confidence peaking above 30 mph according to HREF (19.12Z) probabilities. Thanksgiving Holiday week... The models are showing a pattern shift to occur ahead of Thanksgiving. The current northwest flow looks to transition through a period of zonal flow to having a long wave trough develop over the central part of the country by Thanksgiving. Within this broad scale signal, there are some differences on how the long wave trough develops. The 19.12Z GFS suggests the whole trough will have a positive tilt extending from an upper level low over Hudsons Bay. The 19.00Z ECMWF and 19.12Z CMC suggest a stronger short wave trough coming through the zonal flow looks to dig into the mid-Mississippi River Valley leading to the development of an upper level low within the long wave trough. Looking at the cluster analysis for this time frame, all four clusters show some anomalies for lower heights across the mid to lower Mississippi River Valley with the two clusters predominantly made of ECMWF and CMC solutions have stronger anomalies. With the uncertainty on where the upper level low may develop, the overall probabilities for precipitation still look to be on the low side. Data from the 19.00Z EPS would suggest the probabilities of getting 0.01" Thanksgiving day are in the 30 to 40 range and drop to under 10 for 0.1". Right now, surface temperatures look to be warm enough for any precipitation that occurs to mainly be rain, but some concern that colder air could get drawn in for a light snow event for at least parts of the area. Fortunately, given the current expectation of light qpf amounts, any snow should also be on the lighter side. With the ECMWF being the most aggressive with the upper level low development, it also then lingers some light precipitation chances across parts of the area into Friday but these probabilities look to be on the downswing during the day with a slow eastward movement of the overall system. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1000 PM CST Sat Nov 19 2022 CIGS: low/mid level warm air advection moves in overnight, ushering in a few hours of a VFR mid deck. It should clear by 18z-ish Sun with SCT/SKC condition then for the rest of the day/Sun night. WX/vsby: no impacts anticipated. WINDS: winds becoming southerly overnight and holding under 10 kts. They will pick up a bit for Sunday with mixing promoting a few gusts into the lower 20 kts - not nearly as windy as Saturday. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ DISCUSSION...04/JAR AVIATION...Rieck
Area Forecast Discussion
National Weather Service Goodland KS
415 PM MST Sat Nov 19 2022 .SHORT TERM...(This evening through Monday) Issued at 147 PM MST Sat Nov 19 2022 At the start of the short term period, the latest RAP analysis has a north-northwesterly upper air flow over the CWA being underneath the rear portion of an upper air trough with a ridge over the Pacific coast. Current satellite imagery and surface observations show clear skies over the region with surface winds blowing out of the north- northwest gusting up to around 25 mph. Forecast models show the ridge moving eastward a bit as the trough departs towards the east coast keeping the same flow through the remainder of the day. At the surface, the CWA sees dry conditions throughout the rest of Saturday with some elevated fire weather concerns for areas west of a Wray-Goodland-Leoti line for a few more hours before the evening. Minimum RH values look to be in the upper teens in the southwestern quadrant with the occasional gust around 25 mph expected in this western region. Daytime highs for today look to be in the upper 30s to middle 40s with overnight lows being in the lower to middle teens. On Sunday, forecast guidance shows the CWA remaining underneath the front part of the upper air ridge with a weak subtropical trough over the NM/TX border giving the CWA a generally northerly weak upper air flow throughout the day. At the surface, dry conditions expect to continue across the CWA with little to no cloud cover. While forecast minimum RH values look to be in the middle teens across the CWA, light winds due to the axis of a surface trough being in the region may hinder fire weather potential. Daytime highs for Sunday look to be in the lower to upper 50s while the overnight lows range between the middle teens and lower 20s. For Monday, the CWA looks to get a west-northwesterly flow over the CWA as models show the subtropical weak trough moving eastward. At the surface, dry conditions are expected once again with clear skies expected throughout the day. Forecasted minimum RH values for the afternoon hours west of a line from Joes, CO to Russell Springs, KS look to be in the middle teens. Similar to the previous day, light winds will hinder any fire weather concerns. Monday`s daytime highs expect to be in the upper 40s to middle 50s with overnight lows in the middle teens to lower 20s. .LONG TERM...(Tuesday through Saturday) Issued at 113 PM MST Sat Nov 19 2022 The extended period looks to feature mainly above normal temperatures with a quick shot of cooler air over the Thanksgiving holiday. Tuesday, the upper level pattern looks to remain zonal allowing sunny skies and above normal temperatures to be prominent across the entire area. I opted to up temperatures a few degrees as 850mb temperatures reach around 11C in part to southwesterly surface flow as a result the entire area looks to see highs in the 50s along with overnight lows falling into the low 20s. Wednesday, will another nice for mid to late November with even warmer temperatures in the upper 50s to mid 60s developing across the area. A dry air mass will be in place which will allow RH values to fall rather low into the low to upper teens. Winds will however be less than 10 knots across the area with the exception being across east Colorado (Kit Carson/Yuma counties) where winds may become northwesterly around 15-20 mph for an hour or two before sunset ahead of the next shortwave. As a result elevated fire weather conditions may become realized for a few hours. Wednesday night and into Thursday morning, a quick shot of cooler air as the shortwave mentioned above moves into the area. The overall track of the shortwave remains a bit murky at this time as the ECMWF keeps the colder air and precipitation chances further east out of our area. The GFS has a more southern track which favors cooler temperatures for the area and perhaps some light precipitation along and west of the Colorado border. I have left the forecast dry for now until some consistency shows itself in guidance. Winds will become breezy to gusty behind the trough/front as NW winds around 20 mph will expected along with gusts up to 30 mph. Thanksgiving Day, will be cooler with highs in the mid 40s to low 50s across the area. Gusty winds up to 50 mph at times still look like a possibility however guidance has brought down the strength of the overall wind field; cloud cover may hinder how strong winds do become as well. I didn`t want to stray away from previous forecasts in case the 12Z data is an outlier so the overall forecast remains relatively the same. A blend of the NBM and 90th percentile NBM was used for wind speeds. The remainder of the extended is a bit uncertain as guidance varies quite a bit between the GFS and ECMWF as the GFS develops a compact low over the southern Plains and the ECMWF develops a larger low over the upper Midwest. Ensemble guidance however continues to indicate above normal temperatures continuing to end November. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 413 PM MST Sat Nov 19 2022 For KGLD & KMCK... VFR conditions are forecasted for the period. Winds will pick up this evening out of the west and become more northwesterly around sunrise. The GLD ASOS outage remains. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...076 LONG TERM...Trigg AVIATION...KAK
Area Forecast Discussion
National Weather Service Grand Rapids MI
837 PM EST Sat Nov 19 2022 LATEST UPDATE... Update .UPDATE... Issued at 836 PM EST Sat Nov 19 2022 So far the forecast largely remains on track. I see no reason to change our headlines at this point. We still continue to get locally heavy snow shower and winds continue to gust to around 40 mph near the lake shore and even inland gusts are still in the 25 to 35 mph range. The latest MDOT road conditions show slow travel on just about all area roads from Lansing west to the Lake Michigan shore on I-96 and also on I-94, US-131, US-31, US-127 (Lansing and south) and other major travel routes. While the snowfall rates will be diminishing over the next few hours, we will continue to see accumulating snow, some blowing snow in open area and temperatures will remain well below freezing. Likely in many parts of Southwest Michigan it will be the coldest night of the month so far. The latest run of the RAP model shows the best lift in the DGZ at 8 am was between I-80 and I-94 and currently that is where the strongest snow shower are. That area will continue to pivot southward and be south of I-94 by midnight. There is yet one more area of lift in the DGZ that must come through before this record breaking snow event comes to and end Sunday morning. That one is currently over northern Lower Michigan. That will also slowly rotate southward but this time it will also spread inland. This band of enhanced snow showers is the back edge of the better lift in the DGZ. Once that is through the event is done. We will still see snow showers into midday Sunday but they will be more like snow flurries than anything meaningful for accumulations. As for snow accumulations, I expect 1 to 2 inches of snow yet over ares west of US-127, with the greatest amounts near Kalamazoo and north of Reed City, near US-131. Locations east of US-127 will likely see less than an inch of snow overnight. && .DISCUSSION...(This evening through next Saturday) Issued at 328 PM EST Sat Nov 19 2022 -- Winter storm conditions winding down overnight -- The main change in forecast thinking from previous AFD updates is that poor travel conditions will persist after midnight for the Ludington area. This is where the Lake Superior connection will keep lake effect snow robust. No changes to headlines planned at this time. Most solid area of enhanced reflectivity on the KGRR radar at 245 PM extended from Kalamazoo to east of Hastings. Even though radar looks less impressive farther west with a broken cellular appearance, this area still features visibility well below a mile in many locations including the lakeshore and GRR itself. This is expected to continue the rest of this afternoon. Although not in the SPC Day 1 outlook, there are solid chances for thundersnow late afternoon into early tonight over and adjacent to southeastern Lake Michigan, where SBCAPE will climb towards 500 J per kg in magnitude. Much of this SBCAPE will be realized within the full extent of the -10C to -30C layer, meaning that sufficient ice production will co-mingle with supercooled water and graupel to achieve the differential fall speeds required for charge separation and lightning. By the 9 PM time frame, in addition to ongoing activity around Ludington, lake effect snow will consolidate roughly south of a Grand Rapids to Jackson line and continue well past midnight. By sunrise Sunday, this area will spread east and become diffuse, with perhaps a brief final salute of concentrated snow for the I-94 corridor. -- Recovery weather Sunday, quieter weather thereafter -- Fortunately, the better part of Sunday looks dry with lighter winds. Wind chills will never climb out of the teens however. Our next chance of precipitation will be of the liquid variety on Thanksgiving Day. Precipitation remains in the forecast throughout the Thanksgiving holiday weekend. Given that minimum temperatures will often drop below freezing during this time, there is the possibility for at least some impactful travel conditions. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 659 PM EST Sat Nov 19 2022 We have transitioned from widespread IFR due to the frontal band snow area, to a more lake effect scenario. This will mean VFR at times and LIFR at other times. For example MKG was 9sm BKN055 at 2255z then 30 minutes later they were 2sm -sn blsn bkn028. This is classical for lake effect snow showers. This cellure snow shower pattern will likely continue through about 04z. After that inversions heights fall so snow shower intensity should lessen. Between 06z and 12z I would think we`d vary between VFR cigs and MVFR / IFR in snow showers. After 12z most of our TAF sites should be VFR as the system continues to pull away. The I-94 TAF sites may hold on to MVFR cigs into mid morning. Winds will become less gusty after 06z but there may still be gusts into the 15 to 25 knot range into early evening Sunday. && .MARINE... Issued at 328 PM EST Sat Nov 19 2022 After coordination with surrounding offices, will extend the current Gale Warning to Monday morning. There will be a relative lull during day Sunday and will message that accordingly. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Storm Warning until 7 AM EST Sunday for MIZ037>039- 043>045-050-051-056>058-064>066-071>073. Winter Weather Advisory until 7 AM EST Sunday for MIZ040-046-052- 059-067-074. LM...Gale Warning until 10 AM EST Monday for LMZ844>849. && $$ UPDATE...WDM DISCUSSION...TJT AVIATION...WDM MARINE...TJT
National Weather Service Jackson KY
738 PM EST Sat Nov 19 2022 .UPDATE... Issued at 730 PM EST SAT NOV 19 2022 Mainly minor adjustments have been made to the grids for this evening into the overnight. The main adjustment was to increase sky cover a bit from the previous forecast as the band of low and mid level clouds near an approaching cold front has been a bit more robust than the previous forecast. No other changes were needed at this time other than minor adjustments to hourly temperatures based on observations. && .SHORT TERM...(This evening through Sunday night) Issued at 410 PM EST SAT NOV 19 2022 Key Points: * Record-breaking low temperatures (10s to low 20s) likely tonight. * Wind chill temperatures between 0 and 15 above around sunrise Sunday. * Upper single digit lows possible Sunday night in a few sheltered valleys. At 2055z, satellite showed clear skies over all of eastern Kentucky. This has allowed temperatures to rebound into the mid 30s north of I-75 to the mid 40s in the deeper valleys near the Virginia and Tennessee borders. Winds have also picked up out of the southwest and dew points have dropped as the diurnal heating has allowed momentum and dry air to mix down from aloft. Weather station networks show peak southwesterly gusts on the order of 15 to 30 mph while dew points have settled into the 5 to 15 degree range. Looking upstream, the latest analyses shows another rapidly approaching cold front now aligned from Lower Michigan to southeast Indiana and on into northern Arkansas. This boundary is evident from a leading band of clouds and trailing field of post- frontal cumulus visible on satellite imagery. Through the short-term, guidance is in good synoptic agreement. The cold front will sweep through tonight, likely between 3 and 7z. Moisture is almost nonexistent (PWATS are only near 0.10 ahead of the boundary), and will fall further once the front passes. Thus nothing more than a period of low clouds and possibly a flake are expected, mainly over the northern half of the CWA and also along the highest mountains near the Virginia border. Overnight temperature trends are a bit challenging as winds decouple to varying degrees this evening, particularly in the sheltered valleys. However, strong cold air advection and the stronger pressure gradient along and immediately behind the front should reengage the winds at all locations for at least part of the night. The HRRR gusts and BUFKIT Momentum Transfer products show potential wind gusts of 15 to 30 mph. The gradient relaxes later in the night allowing winds to die down and the valleys to decouple again over the Lake Cumberland and Bluegrass first, during the early morning hours, and then further east through sunrise. Current thinking is that temperatures drop off quickly at those location which decouple (particularly sheltered valleys) this evening before rising slightly with the frontal passage. The ridges and less sheltered locations will likely stay mixed through most of the night with the more significant temperature drop off occurring behind the front. Expect low temperatures of 10F to 15F in the in valleys and sheltered locations west of the Pottsville Escarpment and 15F to 20F in the Coalfield Valleys. The thermal belt should see a northwest to southeast temperature gradient ranging from the mid teens along the Escarpment to lower 20s over far eastern Coalfield ridges. Wind chills/apparent temperatures in the 0 to 15F range are expected by sunrise. On Sunday, high pressure of modified arctic origins will build eastward across the Commonwealth and crest over eastern Kentucky/Central Appalachians on Sunday night. Early afternoon temperatures in the -5 to -8C range at 925mb will only support daily maximum temperatures in the 30 to 38 degree range, north to south, even with bright sunshine. Winds will be much weaker though, thanks to the relaxing pressure gradient. Dew points will drop off to -5F to +5F with afternoon mixing. This dry air in combination with clear high pressure cresting overhead will set the stage for another unseasonably cold Sunday night. Look for widespread lows in the 10 to 15 degree range through the valleys and in the upper teens to lower 20s over the ridges. COOP MOS shows the potential for upper single digit lows in the coldest sheltered valleys. .LONG TERM...(Monday through Saturday) Issued at 402 PM EST SAT NOV 19 2022 Key messages: * Moderating temperatures with large diurnal swings expected through Wednesday. * A cold front approaches Thanksgiving and brings a round of precipitation Thursday night into Friday. * Turning colder behind the front with a chance of snow showers mainly Friday night into early Saturday morning. The models are in good agreement through early next week regarding a quasi-zonal long wave flow pattern to be the rule across the CONUS. Model agreement then breaks down by the middle and end of the week, as vigorous inbound short wave energy from the eastern Pacific allows for significant downstream amplification. Deep troughing will evolve across the middle of the nation and then gradually shift towards the eastern CONUS by next weekend. There still remains a lot of spread in the ensemble data regarding the intensity, timing, and positioning of this feature. This of course translates to lower confidence in the surface details, and have generally stuck pretty close to the blended guidance. Moderating temperatures will be the main story through Wednesday, as high pressure gradually weakens and shifts off to our east with time. Monday will feature a very dry day, as dew point depressions likely push the 40 degree mark, with highs around 50. This will set the stage for another night of teens in the colder valleys Monday night, while ridges stay up closer to 30 degrees. Lows will be a little more tempered across our southeast, as some higher clouds increase out ahead of a southern stream transiting short wave trough. Readings will continue to modify through the middle of next week, with highs in the low to mid 50s Tuesday, and mid to upper 50s Wednesday. Lingering dry air will continue to allow for valleys in our east and northeast to retreat to the 20s both nights. The cold front will approach on Thanksgiving, with increasing rain chances in the afternoon. Overall, the best chance of more sustained shower activity appears to arrive late Thursday night into early Friday morning, where rain chances peak in the likely range. As the deep trough axis shifts east across the Ohio and Tennessee valleys Friday into Saturday, chances of precipitation will be maintained, with cold air advection eventually allowing for a chance of flakes across the area. Again, this is still low confidence at this stage, given the aforementioned model spread. Highs will retreat from the 50s Thursday, to the 40s for Friday and Saturday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 738 PM EST SAT NOV 19 2022 A moisture-starved cold front is approaching the area with a rather persistent. but narrow band of clouds in the 6 to 8kft AGL range. This band of clouds should work across the northern two thirds of the area during the first 6 hours or so of the period. However, even with this band of clouds to affect KSYM and probably JKL and SJS, VFR conditions are expected to prevail through the period. Southwest to west winds up to 10KT are expected ahead of the front, before becoming west to northwest generally between 7 and 12KT immediately behind the front. Winds should then slacken toward 12Z to the 3 to 8KT range. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...GEERTSON LONG TERM...GEOGERIAN AVIATION...JP
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
823 PM CST Sat Nov 19 2022 .UPDATE... Issued at 823 PM CST Sat Nov 19 2022 No significant changes to going forecast this evening, with dry but cold and blustery weather persisting into early Sunday. Lake effect flurries and snow showers will likely affect far northeast Porter county overnight, and may produce reduced visibility and wind-blown minor accumulations though the worst of these conditions will be focused off to the east of the forecast area. Evening GOES vapor imagery depicts a strong mid-level short wave digging across the Midwest, with the core of the mid-level vorticity maxima now east of the forecast area across northern IN/OH. At the surface, a sharp cold front was evident also well east of the cwa stretching from near Cleveland OH to the MO Bootheel. Cold, blustery cyclonic low level flow persisted across northern IL and northwest IN behind the front, with surface dew points in the single digits evidence of the arctic origins of the air mass. While patchy wind- rows of low level strato-cu lingered across parts of the area (mainly far NE IL, LM and NW IN), the combination of deep-layer subsidence in the wake of the mid-level vort and the dry low level advection was working to erode these lingering clouds. While a few isolated or scattered flurries can`t be ruled out of the remaining shallow cloud layer, these should be inconsequential (no vis reductions and no accumulations) and will come to an end as the clouds fully erode through late evening/midnight. The exception to this will be across far northeast Porter county in northwest IN, where a slight northwesterly low level wind component may allow for lake-induced flurries and snow showers to clip areas mainly east and northeast of Chesterton. Radar trends indicate heavier snow showers have been focused east of the Porter/LaPorte county line so far, though RAP and other high-res guidance do suggest a slight veering of the low level winds may maintain some potential for snow showers to affect northeast Porter during the late evening/early overnight hours. Will update the Special Weather Statement for that area shortly, with no significant changes planned to the forecast. Conditions will generally be worse east of our forecast area along the I-94 and I-80 corridors across northern IN and southwest MI. Otherwise, dry but blustery and cold conditions will continue across the area overnight. Westerly winds still gusting 25-30 mph as of 8 pm CST will ease gradually and back southwest overnight, but with temperatures eventually settling into the 5-10 above range (10-15 above in the core of the Chicago metro), wind chills will be in the negative single digits in most spots by early Sunday morning. Ratzer && .SHORT TERM... Issued at 300 PM CST Sat Nov 19 2022 Through Sunday night... Key Messages: * A period of heavier lake effect snow and wind into northeast Porter County through this evening * Bitterly cold tonight into early Sunday with lowest wind chills of 0 to -10F * Gusty winds Sunday PM and especially Sunday night, when gusts up to 35-40 mph will be possible The mid-winter pattern of daily flurries and snow showers has again not disappointed today, with scattered bursts of heavy snow in the most robust snow showers over northeast Illinois and northwest Indiana. Given this behavior, we probably weren`t far off moisture depth wise from higher end type snow squalls. The threat for additional brief heavier snow bursts will be winding down and focus closer to the lake through about 5 PM CST. Concern then shifts to a period of very favorable lake effect parameters for northeastern Porter County this evening. The extreme lake induced instability with such a cold air mass (-17C at 850 mb at KMPX at 12z) overhead will compensate for the non- classic 290-300 deg wind direction for multi-cellular LES into northeast Porter and particularly LaPorte Counties. Well below freezing air temperatures, winds still gusting up to 35 mph or so and falling snow suggests some hazardous travel conditions could develop. Explicitly forecasting 1-1.5" accumulation for the area of concern. Contemplated issuing a short-fused Winter Weather Advisory for Porter County, but opted to hold off with some uncertainty on magnitude of any impacts and higher confidence in them for northern LaPorte County. Planning to issue a SPS and hitting the the threat in one of the afternoon Weather Story graphics. Will continue to monitor trends over the next few hours. Otherwise, the main story for the rest of the area will be the mid-winter cold. Very low dew points in the dry Arctic air mass supports some mid-high (positive) single digit lows, especially in favored cold spots of northern Illinois. The surface high passing well to the south will mean some wind (but certainly not like what`s occurring as of this writing) through the night, yielding minimum wind chills early Sunday of 0 to -10F. The PV anomaly responsible for the bitterly cold weather will quickly kick out on Sunday, with southwesterly warm advection in its wake. May see some mid clouds through early afternoon followed by clearing. Southwesterly winds will increase in response to pressure falls from an approaching frontal trough, with afternoon gusts up to 25-30 mph. Warm advection in this setup with no antecedent cloud cover will enable high temps to recover to the lower to mid 30s, though the wind means it certainly won`t be pleasant outside. A robust low level jet (45-50 kt at 950 mb) will develop Sunday night, so gusty winds will continue and in all likelihood increase in the late evening and overnight. With the low base of the LLJ, could see some sporadic gusts up to 35-40 mph, highest in/near Chicago and points north. After any small temperature drop in the evening, temperatures will slowly rise overnight into early Monday. Castro && .LONG TERM... Issued at 204 PM CST Sat Nov 19 2022 Monday through Saturday... The week of Thanksgiving will start off on a warmer and drier note compared to what we`ve been dealing with the past couple of days. Monday will likely see many areas reach the 40s for the first time in about a week with a relatively "warmer" starting point for temperatures in the 20s at daybreak and mostly sunny to partly cloudy skies through most of the day contributing to the likelihood of that occurring. How many areas get to 40 and just how warm our warmest locations will be on Monday will depend upon how long warm air advection off of southwesterly winds will be able to persist over the course of the day before a surface trough axis shifts across the region and veers winds around to a westerly and eventually northwesterly direction. With high pressure to our southeast on Tuesday and Wednesday, southwesterly winds will return for a more prolonged stay and will help high temperatures to climb to seasonable readings for this time of year in the 40s and 50s on both days. A couple of subtle shortwave disturbances will also swing through the region between Monday and Wednesday, but an overall lack of moisture through the atmospheric column should keep us precipitation-free through this time period, with increasing high cloud cover being the only discernible sign of the passage of these waves. A potentially different story could play over the latter half of the week as a potent upper-level northern stream trough enters the Pacific Northwest and digs southeastward. However, confidence in the forecast for Thanksgiving and beyond remains quite low with guidance continuing to offer up a hodgepodge of possible solutions and not much consistency being exhibited between successive operational runs of most global models at this point. The main forecast uncertainties revolve around how much phasing will occur with this northern stream wave as it interacts with the southern stream and any embedded perturbations within it, as well as where the northern stream wave intercepts the southern stream. As can be implied, models remain all over the place with how they resolve this interaction. Some operational runs suggest that the northern and southern stream waves will phase favorably and induce surface cyclogenesis that will eventually see a relatively deep surface low track into and occlude over the Great Lakes, Mid-Atlantic, or New England, presumably resulting in a healthy dose of precipitation somewhere in these regions over the holiday weekend. In a scenario like this, precipitation types of both rain and snow appear to be in play for our forecast area, though the exact precipitation type evolution and amount of precipitation that we will receive will depend on where exactly we end up relative to the track of the surface low, as well as how much this low ultimately deepens. Other solutions suggest that there will be little to no constructive phasing of the northern and southern stream waves, or that it will occur far enough away from us where the exact degree of phasing may not matter much for the purpose of our late week forecast anyways. If a scenario like this were to verify, then we could get through the holiday weekend without seeing much of any precipitation at all. Considering all of the existing uncertainties, did not stray from the NBM, whose chance PoPs for the Thanksgiving afternoon through late Friday time frame appear to be reasonable and more or less in line with ensemble mean guidance. The main message for now remains that there`s still a chance for rain and/or snow to occur in our forecast area over the holiday weekend, but that confidence in the exact specifics of how things will play out remains quite low at the moment. Nevertheless, continue to keep an eye on the forecast in the coming days, especially if you have travel plans for the holiday, as there is a possibility that weather could cause impacts over a good chunk of the eastern CONUS this holiday weekend. Ogorek && .AVIATION... For the 00Z TAFs... Aviation Forecast Concerns: * Isolated to widely scattered flurries/light snow showers ending early this evening. No accumulation. * Blustery west winds gusting near 30 kt gradually easing early this evening. Winds become southwest Sunday, then increase again Sunday evening with gusts increasing above 25 kts. Digging upper level trough will move quickly east of the region this evening, with blustery west winds continuing to pull drier air into the region. This will allow lingering isolated to widely scattered flurries/light snow showers to end early, and these are not expected to produce impacts to visibility or accumulations. Will see a scattered to broken VFR deck linger through the evening, before clearing out late. VFR conditions are expected through the forecast period. West winds were still gusting near 30 kts at both ORD/MDW as of 23Z, though these will gradually ease early this evening. Winds back southwesterly Sunday and become a bit gusty again during the afternoon. Winds look to strengthen Sunday evening as another area of low pressure deepens north of the Great Lakes, with gusts again approaching 30 kts from the southwest. Ratzer && .MARINE... Issued at 426 PM CST Sat Nov 19 2022 Westerly gales will diminish late this evening from Winthrop Harbor to Gary and in the pre-dawn hours of Sunday from Gary to Michigan City. Hazardous waves for small craft will persist through the morning from Gary to Michigan City, with hazardous southwesterly winds up to 30 kt developing in the afternoon for the entire nearshore. These southwest winds will further increase to gales Sunday evening in response to low pressure passing well to the north as conditions remain unstable over the lake. The strongest winds in this setup will probably occur from 2-3 miles from shore and out to the open waters. Issued a new Gale Warning from 6PM Sunday to 4AM Monday. Castro && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Gale Warning...Winthrop Harbor to Gary IN until 9 PM Saturday. Small Craft Advisory...Winthrop Harbor to Gary IN until 3 AM Sunday. Small Craft Advisory...LMZ740-LMZ741-LMZ742-LMZ743...noon Sunday to 6 PM Sunday. Gale Warning...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...6 PM Sunday to 4 AM Monday. Gale Warning...Gary to Michigan City IN until 3 AM Sunday. Small Craft Advisory...LMZ744-LMZ745...3 AM Sunday to 6 PM Sunday. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Phoenix AZ
424 PM MST Sat Nov 19 2022 .UPDATE... Aviation update. && .SYNOPSIS... A weak and dry weather system passing through the region today will bring another round of breezy winds, particularly across portions of southeastern California today and then tonight into Sunday morning for higher terrain areas east of Phoenix. Dry conditions and near to slightly below normal temperatures will continue through the middle of next week before even warmer temperatures are likely late next week as a stronger high pressure system moves over the region. && .DISCUSSION... Latest water vapor imagery and streamline analysis reveal a closed low in the mid-levels atop south-central Arizona. Surface winds also suggest the presence of an inverted trough at the lower levels. Weak vorticity-forced ascent is situated across southeastern Arizona, though PWATs remain too low for organized precipitation and only a few clouds are expected across far eastern Gila County. Biggest sensible impact across the forecast area has been some windy conditions, mainly across portions of southeastern California, and the Chocolate Mountains in particular, where the flow is largely perpendicular to the terrain. Observations suggest gusts likely reached 40 mph earlier this morning, however winds will continue to taper off early this afternoon. Further east across central Arizona, stronger northeasterly winds just above the surface continue to mix out, resulting in gusts of 20 to 25 mph across the Valley. Latest HRRR also suggests the windy conditions will dissipate this afternoon as the surface high across the Great Basin weakens. The focus for windy conditions will shift into southeastern Arizona Sunday as the low-level flow acquires more of an easterly component around the weakening low-level trough. However, ECMWF EFI values indicate the strongest gusts will mainly be confined to the higher terrain south and east of Phoenix early Sunday morning. Nevertheless, latest ECMWF indicates gusts of 15 to 20 mph are still likely in the Phoenix area. Ensemble suites are in good agreement indicating the flow will become more zonal early next week. This will translate into near normal temperatures through Wednesday. Thereafter, 90 percent of the multi-model ensemble members suggest the flow will become more amplified across the CONUS with a ridge building eastward from the Eastern Pacific into the Desert Southwest. This will yield above normal temperatures, likely reaching at least the upper 70s across the Phoenix area Thursday-Saturday. There is also a 40 percent chance of reaching the 80 degree mark in Phoenix and El Centro Friday. However, this would still fall well short of daily records, which are in the upper 80s. && .AVIATION...Updated 2325Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Northeasterly winds will persist this evening and through the overnight hours. LLWS concerns are possible overnight but currently expect this to remain just below TAF thresholds. A period of breezes will be possible late Sunday morning as the inversion breaks. Skies will remain mostly clear. Southeast California/Southwest Arizona including KIPL and KBLH: Northwesterly winds will persist through the forecast period, weakening quickly this evening then mostly below 10 kt through Sunday afternoon. Skies will remain mostly clear. && .FIRE WEATHER... A dry weak upper level disturbance moving through the region today will bring another round of breezy conditions for much of the area. Locally windy conditions with wind gusts of 30-45 mph will be possible across southeast California today, mainly over ridgetops, and easterly winds of 30-40 mph possible tonight through Sunday morning across the Arizona high terrain east of Phoenix. By Monday, tranquil weather conditions are expected, lasting through most if not all of next week. Temperatures will be near to slightly below normal through the middle of next week before warming to slightly above normal late next week. Moisture levels will remain quite low through the period with daily MinRHs in the teens across the western districts to 15-25% across the eastern districts. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Hirsch AVIATION...Iniguez FIRE WEATHER...Kuhlman