Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/16/25


Area Forecast Discussion
National Weather Service La Crosse WI
947 PM CST Wed Jan 15 2025 .KEY MESSAGES... - Snow showers will move through the region late this afternoon through tonight. The highest chances (60-90%) for snow showers will be along and north of I-94 with lower probabilities (20-50%) elsewhere. Some patchy freezing drizzle cannot be ruled out (10-20% chance) late this evening and overnight. - Warmer temperatures move in for Thursday and Friday with highs in the 30s and 40s areawide. - Bitterly cold air moves into the region this weekend and to start next week with very high probabilities (60-90% chance) for morning wind chills of -25F and colder areawide. && .DISCUSSION... Issued at 158 PM CST Wed Jan 15 2025 Rest of Today - Tonight: Snow Showers Move Through Area Surface analysis this afternoon depicts our area being subjected to surface southwesterly flow and an approaching warm front to our east. In the upper-levels, GOES-16 water vapor imagery and RAP 500mb heights show northwesterly flow aloft with a shortwave progressing into the Great Lakes region. As we continue later this afternoon, low-level isentropic ascent ahead of this boundary coupled with warm air advection will continue to propel ongoing snow showers across central Minnesota into our local area. Initially, abundant low-level forcing appears in play to push saturation well into the dendritic growth zone giving high confidence that the initial p-type mode will be snow late this afternoon and into this evening. Accumulations generally appear fairly minimal with fairly low (10-30%) probabilities for over 0.5" in the 15.12z HREF south of I-94, assuming a near climatology SLR. Probabilities for over 0.5" are decently higher north of I-94 where the CAMs indicate more shower activity with values generally of 50 to 80%. The more tricky part of the forecast as we get later into the evening will be as low-level lift lessens and if a period of freezing drizzle will be possible late this evening and overnight. Based on RAP/HRRR soundings, lessening saturation in the dendritic growth zone can be noted at sites such as La Crosse and Eau Claire. However, the issue in this case is relatively steep lapse rates atop this saturated layer that may enable some convection into the DGZ regardless. As a result, confidence is very low if freezing drizzle will be able to manifest in this environment. However given some fairly dry RH fields south of I-94 across some of the CAMs in the DGZ, have opted to mention some slight chances (10-20%) for freezing drizzle from 03z to 09z to account for this lower-end possibility. Thursday - Friday: Above Normal Temperatures Starting tomorrow, upper-level ridging and returning southwesterly flow at the surface will aid in trending our temperatures above normal for Thursday with highs in the upper 20s to middle 30s. As the ridge axis moves overhead for Friday, this will likely be the warmest day with median high temperatures in the grand ensemble (GEFS/EC/Canadian ensemble) anywhere from the middle 30s to lower 40s for Friday afternoon. This is further supported by the 15.00z EC Extreme Forecast Index which indicates a 60 to 80% probability of exceeding model climatology for high temperatures on Friday. Certainly Friday looks like the best day in the forecast period to get outside, especially when considering the very cold temperatures moving into our area starting this weekend. Saturday - Tuesday: Very Cold Air Moves In By the time Saturday approaches, a robust upper-level trough will begin to swing into the region with an arctic front pushing through the area during the pre-dawn hours on Saturday. As strong northwesterly flow advects arctic air into the region, temperatures will fall through the teens and single digits through the day on Saturday and below zero overnight Saturday night. As we head into Sunday morning, the main axis of cold air begins to move overhead with 850mb temperatures falling to around -30C as shown in both the 15.12z GFS/EC. This will instigate a very cold period from Sunday into Tuesday with this airmass directly overhead. Probabilities during this period already are very high (60-90%) for morning wind chills under -25F during this period (20-60% chance for -35F!) in the recent grand ensemble (GEFS/EC/Canadian ensemble). Additionally, the daytime hours may very well still be hazardously cold with the grand ensemble (GEFS/EC/Canadian ensemble) having modest probabilities for sub -25F wind chills even during the daytime hours on these days with afternoon high air temperatures not reaching 0 in some locations. Overall, seems like the coldest period we have seen thus far this winter with confidence increasing for hazardously cold temperatures. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1000 PM CST Wed Jan 15 2025 As has been the pattern tonight, a drier low levels has resulted in backing off of MVFR ceiling onset at the 16.06Z TAF issuance. Immediate concern will be a clockwise wind shift from the southwest at 16.04Z to west-northwest over the next few hours. Associated front is moving from west to east. Current (16.04Z) wind shift seen in surface observations from southwest Minnesota through eastern Minnesota. Have delayed MVFR ceiling onset until the morning hours as low level cold air advection saturates the lowest levels from north to south. Stronger, albeit still low, confidence on low level dry air between high resolution models has caused said delay. Extent and timing remain low confidence. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Naylor AVIATION...JAR
Area Forecast Discussion
National Weather Service El Paso TX/Santa Teresa NM
426 PM MST Wed Jan 15 2025 ...New AVIATION... .KEY MESSAGES... Updated at 423 PM MST Wed Jan 15 2025 - A Pacific storm brings gusty winds and patchy blowing dust for Friday. - Several surges of cold air begin moving in late on Saturday with next week`s temperatures back to well below normal. && .DISCUSSION... Issued at 220 PM MST Wed Jan 15 2025 Fairly quiet, seasonal weather is in place across the Borderland, and that will remain the case through tomorrow. Southern NM and Far West TX are sitting beneath a s/w ridge, sandwiched between a long wave trough covering the eastern half of the CONUS and a Rex Block over the Pacific and West Coast. The low off the Baja Coast will translate toward the ENE, coming ashore by mid-day Thursday. High clouds will filter in from the south, but tomorrow`s weather will remain quiet and a little warmer than today. The trough will open up and continue its ENE trek across NM by Friday afternoon, placing its H500 jet across the International Border and into Mexico. At the surface, a broad area of low pressure, less than 1000 mb, will form over the TX Panhandle. The pattern will make for a breezy to low-end windy day with blowing dust along and south of I-10 the main concern. Wind gusts look to range 35-45 MPH with some higher gusts approaching or briefly exceeding 50 MPH for our higher elevations and east slopes. I will hold off on any advisories on this shift as probabilities to exceed 50 MPH gusts are only about 50%. As the system slips through the region it will bring a slight chance of precipitation to the Gila, but it is largely expected to be a dry passage. It should be noted, however, the HRRR is an aggressive outlier with the exit region / warm-conveyor belt of the jet and produces light to moderate rain early Friday morning, especially toward the International Border and into our Texas counties. This solution appears to be an outlier, however. The system exits quickly Saturday morning. East slope areas will still be somewhat breezy to start the day, but winds will decrease by afternoon. Temperatures will be a few degrees cooler than Friday but will still be near or just above normal. During the day, a s/w will be dropping south along the Front Range of the Rockies while the Pacific Ridge continues to amplify. This pattern will set the stage for another arctic outbreak, ushered southward by the aforementioned s/w. This Arctic air will make its first push through our CWA late Saturday into Sunday, setting highs back by 10 to 15 degrees. We keep the easterly tap on Monday with cooler air continuing to push in. Latest guidance has warmed temperatures a tad for Monday, however. By Tuesday, another s/w will drop south along the Front Range of the Rockies. It will push more arctic air into the CWA for Tuesday. Highs will struggle to get out of the 30s. Morning lows during this period will be in the teens and 20s, with wind chills into the lower teens and single digits. Mountains will see wind chills below zero. Cold weather advisories will probably be needed. Forecast guidance continues to struggle with how cold it will get, but typically the colder side of guidance tends to be correct. This arctic outbreak looks to be as cold, if not colder than the one earlier this month. In terms of snow, probabilities still look pretty low except for our mountains. Cluster analysis and a look at ensemble members favor a solution where Tuesday`s s/w comes through with little amplitude and thus little dynamics and moisture. NBM had POPs 15-20 percent, but I lowered them for the lowlands. I kept the POPs in the mountains given upslope flow and the tendency for arctic air to squeeze moisture out of the air. Either way, any snowfall impacts look minor to none. && .AVIATION... (00Z TAFS) Issued at 423 PM MST Wed Jan 15 2025 VFR conditions across the entire regions, including all terminals, through the period. Skies varying from SKC to BKN250. Winds NW 6-12kts through 02z...then diminishing to 2-6kts and turning toward more northerly. && .FIRE WEATHER... Issued at 220 PM MST Wed Jan 15 2025 The forecast will feature minimal to no fire concerns. Temperatures through Saturday will be seasonal or just above normal with afternoon RH values in the upper teens and into the lower 20s. Winds will be light for Thursday but will become breezy for Friday. Saturday will feature quiet conditions, but by Sunday we begin a cooling trend with the arrival of arctic air. Venting will be poor to fair for Thursday but will generally be excellent on Friday. && .PRELIMINARY POINT TEMPS/POPS... El Paso 35 62 42 62 / 0 0 0 0 Sierra Blanca 32 60 38 57 / 0 0 0 10 Las Cruces 29 58 35 59 / 0 0 0 0 Alamogordo 24 56 29 58 / 0 0 0 0 Cloudcroft 20 43 24 35 / 0 0 0 0 Truth or Consequences 25 53 31 58 / 0 0 0 0 Silver City 29 54 29 47 / 0 0 10 0 Deming 29 58 32 57 / 0 0 0 0 Lordsburg 27 59 28 54 / 0 0 10 0 West El Paso Metro 36 60 41 59 / 0 0 0 0 Dell City 27 59 34 60 / 0 0 0 0 Fort Hancock 32 66 37 63 / 0 0 0 10 Loma Linda 34 56 38 52 / 0 0 0 0 Fabens 34 64 39 62 / 0 0 0 0 Santa Teresa 31 58 37 57 / 0 0 0 0 White Sands HQ 34 58 40 59 / 0 0 0 0 Jornada Range 24 56 28 59 / 0 0 0 0 Hatch 24 58 29 60 / 0 0 0 0 Columbus 32 59 37 58 / 0 0 0 0 Orogrande 27 57 32 57 / 0 0 0 0 Mayhill 23 58 32 47 / 0 0 0 0 Mescalero 21 51 27 45 / 0 0 0 10 Timberon 20 51 24 45 / 0 0 0 0 Winston 17 51 21 51 / 0 0 0 0 Hillsboro 27 55 31 56 / 0 0 0 0 Spaceport 22 55 25 59 / 0 0 0 0 Lake Roberts 26 56 27 47 / 0 0 10 10 Hurley 24 55 28 50 / 0 0 0 0 Cliff 15 64 17 57 / 0 0 10 0 Mule Creek 26 58 28 50 / 0 0 20 10 Faywood 29 54 32 51 / 0 0 0 0 Animas 26 61 29 58 / 0 0 10 10 Hachita 27 58 29 57 / 0 0 0 0 Antelope Wells 29 59 35 57 / 0 0 10 10 Cloverdale 33 59 36 52 / 0 0 10 10 && .EPZ WATCHES/WARNINGS/ADVISORIES... TX...None. NM...None. && $$ FORECASTER...14-Bird
Area Forecast Discussion
National Weather Service Indianapolis IN
952 PM EST Wed Jan 15 2025 .KEY MESSAGES... - Scattered light snow showers along and northeast of the I-74 corridor expected early Thursday morning. Snow accumulations under an inch. - Warm up Friday with rain Friday evening changing to snow overnight. - Bitterly cold air is expected Sunday through the middle of next week with multiple nights of subzero lows likely && .FORECAST UPDATE... Issued at 952 PM EST Wed Jan 15 2025 Another cold night is already upon central Indiana, albeit much closer to seasonable normals than last night`s subzero readings. An overall weak disturbance approaching from the northwest will continue to promote south-southwesterly breezes and thickening clouds for most of the region. This will serve to hold temperatures steady in the 15-20F range for most locations through the late evening...before a modest warming occurs towards daybreak. Have nudged up tonight`s minimums for several zones, yet kept values in the low teens for far southwestern counties where clouds have been slower to thicken. Wind chills in the single digits will rise through pre-dawn hours to 10-15 degrees for a majority of the region. Model divergence on tonight`s snow shower threat includes HRRR trying to bring snow showers to southwestern Indiana, while latest NAM runs hold any measurable precipitation north of the CWA despite a H500 vort max slicing down the I-74 corridor towards the middle of the state. Therefore held with slight chance/low-chances of snow showers along/north of I-74...which follows with upstream echoes so far maintaining themselves through the Quad Cities area. Timing should be only a few hours for any given location, mainly after 6Z. && .SHORT TERM (This evening through Thursday)... Issued at 259 PM EST Wed Jan 15 2025 An arctic airmass has settled over the state today with temperatures struggling to rise from the sub-zero lows into the teens this afternoon. Focus shifts to the next weak system approaching the area from the northwest tonight that could bring clouds and scattered snow showers to Central and North Central Indiana. A positively tilted mid level trough and an associated jet streak drop southeast from Canada into the Ohio Valley and Great Lakes region. The parent low is all the way up near the Hudson Bay with the main source of any moisture coming from the Pacific or Great Lakes. The antecedent airmass is drier than what guidance depicts based on observation today, so will have to take this into account as well as the system does not have a ton of moisture to work with. Forecast soundings and BUFKIT cross sections from short term models show a brief period when the trough axis swings through where modest lift aligns with enough saturation through the lower levels and DGZ to support isolated to scattered snow showers. Best moisture and forcing for ascent appear to be along and northeast of the I-74 corridor within the 2am - 9am timeframe before much drier air moves in aloft. Any snow amounts should be light and under a half inch in locations that do see a snow shower. Areas north and east of the Indianapolis Metro have the highest likelihood of picking up minor accumulations as moisture streaming in off Lake Michigan may enhance snow shower activity locally. A tightening surface pressure gradient and steepening low level lapse rates during the day on Thursday should result in increase west northwesterly winds upwards of 20-25+ mph during the late morning and afternoon hours. Mixing and slight "warm" air advection aloft as the arctic airmass retreats should yield highs near and just above the freezing mark tomorrow afternoon; however breezy conditions will keep wind chill in the low to mid 20s. && .LONG TERM (Thursday night through Wednesday)... Issued at 259 PM EST Wed Jan 15 2025 Transient mean ridging will pass on Friday bringing a temperature increase to warmer conditions than we have experienced since the 2nd. There is some uncertainty on temperatures from the effects of residual snow cover albedo. So we won`t go as high as statistical/MOS guidance. Stratus may be present in the morning but should clear by late morning or midday as MSLP pattern changes. A southern stream wave should force a precipitation event Friday night with most ensemble members in the 0.25-0.50 range. There should be enough warm advection for a deep enough above freezing layer for all rain at precipitation onset. As cold advection starts later in the evening/overnight, thermal profiles will become favorable for snow. Timing of sufficiently cold onset vs QPF is unclear at the moment, but it does appear that enough cold and precipitation will overlap for some accumulation, especially across the northwest half. More details as the event nears. Over the weekend a northern stream wave will phase the southern stream and result in a deep highly anomalous trough supporting dislodging of Arctic air into our region. The coldest temperatures of the season are expected with highs Sunday in the teens, and single digits Monday. MSLP pattern isn`t the best for optimal radiative conditions, but the magnitude of the Arctic air mass should be enough for sub-zero overnight lows during this period. Some modification may occur by the latter half of next week as the anomalous trough moves east. Even then, residual Arctic air mass and modest at best warm advection will keep temperatures 10-15 degrees below normal. The Day 8-14 period looks to see some moderation but still colder than normal given a persistent eastern CONUS trough. Some minor precipitation chances may occur given the progressive pattern with minor shortwaves indicated in medium-range guidance. && .AVIATION (00Z TAF Issuance)... Issued at 635 PM EST Wed Jan 15 2025 Impacts: - Low chances -SHSN late tonight within 06Z-11Z - MVFR ceilings starting during 08Z-15Z Thursday...continuing into at least early evening Thursday - Gusty winds to 20-25KT during daytime hours Thursday Discussion: Ceilings will fall through VFR levels this evening as an overall weak disturbance approaches from the northwest. MVFR CIGs are expected over at least KIND/KLAF by 09Z tonight...with mainly low- VFR expected at KHUF/KBMG through daybreak. -SHSN may drop VIS to MVFR at KIND/KLAF late tonight through 12Z, with confidence too low to include -SHSN at KHUF/KBMG. MVFR CIGs to continue Thursday... although low-VFR should return at KIND Thursday evening. Winds will slowly veer through Thursday afternoon. South-southwest to southwesterly flow this evening will be sustained to mainly 10KT or less. Late tonight southwesterly winds will gust up to 18-20KT. Thursday`s overall westerly to west-northwesterly winds will be sustained at generally 9-14KT, with gusts to 20-25KT through most of the day. && .IND WATCHES/WARNINGS/ADVISORIES...None. && $$ UPDATE...AGM SHORT TERM...CM LONG TERM...BRB AVIATION...AGM
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
844 PM CST Wed Jan 15 2025 .KEY MESSAGES... - Scattered gusty snow showers may lead to local slick spots mid-evening and overnight. - Friday will be blustery with above normal temps, then the coldest air mass of the season thus far will arrive Sunday and linger through mid next week with dangerously low wind chills possible at times. - Rain Friday evening changing to wet snow before ending early Saturday, primarily for areas southeast of I-55. - During the cold snap, most if not all of the precip will be lake effect snow, potentially including northeast Porter Co. at times. && .UPDATE... Issued at 844 PM CST Wed Jan 15 2025 Other than a bit of very minor fine-tuning of the timing, no real changes made to the forecast for the snow showers tonight. First band seen on radar moving across northwestern portions of CWA is encountering dry low levels and mainly producing virga to a few flurries. Additional echoes upstream across southern WI will likely produce scattered snow showers across the area from late this evening into the first half or so of the overnight hours. Accumulations of a coating to a half inch still look right on target. One change to the forecast for tonight was to remove mention of freezing drizzle and flurries for late tonight and Thursday morning. Upstream observations show very little stratus and what stratus there is remains high based and unlikely to produce drizzle. Vast majority of the ceiling guidance suggests that cloud bases will remain mostly VFR (>3kft) late tonight into Thursday morning, which is what upstream observations also show. Finally, the latest forecast soundings from the HRRR and RAP both show mean RH values less than 85% in the 0-1km layer with low level subsidence. Freezing drizzle is very challenging to forecast, but struggling to find much support for FZDZ, except in the NAM which is notorious for being too moist/saturated in the boundary layer in the winter. Did nudge temps upward a bit overnight, especially over the northwestern CWA where lack of snow cover and strong southwest winds and resultant warm air advection likely results in slowly rising temps tonight. By sunrise, temperatures should warm into the low to mid 20s, warmest over the northwestern CWA. Upstream dewpoints are mostly in the uppper single digits to mid teens, so that should result in T/TD depressions of at least 5-8F by morning, which also supports the notion that freezing drizzle is unlikely. - Izzi && .DISCUSSION... Issued at 246 PM CST Wed Jan 15 2025 Through Thursday Night: An amplifying mid to upper-level trough on the northeast periphery of a stacked strong jet will dig southeastward across the western Great Lakes through tonight. Robust deep forcing within the left-exit of the mid to upper-level jet and a ribbon of low-level WAA/isentropic ascent will feed into seasonably steep mid-level lapse rates to produce scattered bursts of gusty snow showers across northern Illinois and northwest Indiana mid-evening through the early overnight hours. Upstream observations show that a broken axis of potent snow showers is already present across central Minnesota early this afternoon, further supporting tonight`s expectations. While the overall coverage of the snow showers is less certain, the strongest snow showers will be capable of producing quick accumulations of up to a half inch along with SW/W gusts in excess of 25 mph. By the pre-dawn hours, accumulations will likely range from a trace to a couple localized narrow bands up to around 1" across northern Illinois (particularly northeast Illinois) and northwest Indiana. With the loss of deeper moisture behind the mid/upper-level trough, cloud ice will become less prevalent in the lingering low-level stratus. Though low-level ascent will be waning with time from west to east, patchy freezing drizzle and/or light poor-quality snow/flurries may proceed the snow showers for several hours. This includes much of northeast Illinois through around mid-morning. Overall, sporadic impacts are possible due to locally slippery spots from the snow showers and freezing drizzle. Temps should warm to around the freezing mark for several hours late morning through the afternoon Thursday as stratus persists across the area. Eventually, a gradually lowering inversion in response to a passing mid-level ridge will erode the remaining stratus from southwest to northeast late Thursday night into Friday morning. Kluber Friday through Wednesday: Deep 985-990 mb surface low pressure will pass north of Lake Superior on Friday, with the associated cold frontal trough approaching from the midwest. A tight pressure gradient between low pressure to our north and west and expansive high pressure to the southeast amidst a robust low-level jet aloft will set the stage for blustery south-southwesterly warm air advection. Most of the guidance scours out any lingering low clouds early in the day, but this isn`t a sure thing. In addition, the existing snow cover over the southeast 1/2 to 2/3 or so of the CWA (and well south of there) casts uncertainty on how warm temps will get given that the brisk southerly flow will be occurring over expansive snow cover. There should be a northwest (milder) to southeast high temp gradient over the area, possibly sharper in reality than we can depict at this range. Our afternoon forecast officially shows upper 30s to lower 40s near and northwest of I-55 (mildest in northwest IL) and mid 30s southeast of I-55. Lower mixing depths where temps stay cooler should keep wind gusts in check a bit, though it`ll be blustery areawide with gusts up to 30-35 mph. Banded precip will blossom in the frontal trough Friday evening as cold air advection ensues aloft, primarily southeast of I-55. Expect a sharp gradient on the northwest edge of the precip shield, which will be further refined in subsequent updates. An initially above freezing profile will result in the precip starting as rain, though for areas that do receive precip, ptype should mix with and then change to wet snow before ending in the pre-dawn hours of Saturday. A slushy coating of snow is possible on colder surfaces, however mostly above freezing air temps will likely limit travel impacts. Temperatures will primarily flat-line Saturday (low 20s NW to near 30F southeast) amidst blustery north-northwest winds gusting up to 30 mph and lingering post-frontal stratus, with perhaps some spotty flurries. PM wind chills will be back down in the single digits and lower teens. Lake effect parameters will be somewhat marginal on Saturday, though sufficient to hold onto lower chance (~30%) PoPs into northeast Porter County. As cross-Polar flow takes hold Saturday night and onward, a truly Arctic air mass will arrive with 850 mb temps bottoming out as low as -25 to -30C in the Sunday night-Tuesday morning timeframe. The lack of snow cover in parts of our area (which will likely see some further erosion on Friday) and upstream makes it a bit uncertain exactly how cold temps and wind chills may get in this stretch. The lowest temps will occur Sunday night-Monday AM and Monday night-Tuesday AM when sub-zero lows are forecast area wide along with minimum wind chills ranging from -15 to -25F. Daytime high temps will likely be held into the positive single digits for the northwest half of the area on Sunday and area-wide on Monday-Tuesday. Some moderation back to merely below normal will occur by next Wednesday. The northwest to westerly flow pattern during the cold snap will likely relegate precip chances to persistent lake effect snow for the favored snow belts, possibly clipping northeast Porter County at times. While we certainly can`t rule out subtle low amplitude impulses being able to wring out light snow or flurries in such a cold pattern, the main message is to prepare for the at times dangerously cold conditions. Castro && .AVIATION /00Z TAFS THROUGH 06Z FRIDAY/... Issued at 602 PM CST Wed Jan 15 2025 - A 2-3 hour period of snow showers (occasional IFR VSBY) is expected late this evening into the early portion of the overnight hours. A fast moving weather system will move across the region tonight and result in a period of snow showers across the terminals late this evening into the early portions of the overnight hours. In the more robust snow showers visibility will likely drop to IFR at times. Snow accumulations around a half inch are expected during this period of snow showers. Upstream observation and satellite trends show a rather quick transition to VFR and even some clearing a couple of hours after the snow showers pass. Guidance is hanging onto MVFR CIGS after the snow showers and certainly climo would favor some stratus lingering in the wake of the snow showers, so have maintained MVFR CIGS overnight and through the day Thursday. If stratus doesn`t materialize as forecast, then later TAFS will likely adjust to an earlier transition to VFR. - Izzi && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...Small Craft Advisory until 3 PM CST Thursday for Winthrop Harbor IL to Gary IN. Small Craft Advisory until 9 PM CST Thursday for Gary to Burns Harbor IN-Burns Harbor to Michigan City IN. && $$ Visit us at weather.gov/chicago
Area Forecast Discussion
National Weather Service Melbourne FL
855 PM EST Wed Jan 15 2025 ...New UPDATE... .KEY MESSAGES... Issued at 300 PM EST Wed Jan 15 2025 - Cooler than normal conditions through Friday with the coldest temperatures forecast Friday morning. - An active pattern returns this weekend with higher rain chances, breezy conditions, and above normal temperatures. - Below normal temperatures return early next week behind Sunday`s cold front. && .UPDATE... Issued at 855 PM EST Wed Jan 15 2025 Mid to high level clouds will continue to push E/NE across central Florida overnight. Radar has been showing some light returns with this cloud deck, but MRMS reflectivity and sfc obs indicate that most of this continues to not reach the surface due to pockets of drier air below 500mb. Greatest potential for some limited light rainfall accumulation will be across north Florida later tonight into northern Lake and Volusia counties ahead of a passing SW aloft. However, can`t completely rule out some light sprinkles at times late tonight farther south. For now have keep mentionable rain chances, around 20 percent, north of Sanford. Lows tonight will be near to slightly cooler than normal in the low to mid 40s across Lake/Volusia counties and upper 40s to low 50s farther south (except mid 50s along coastal Martin County). These values are near to just below NBM guidance, and not quite as cool as MOS output, as cloud cover and weakening northerly winds should help keep temps up a bit tonight. && .PREVIOUS DISCUSSION... Issued at 300 PM EST Wed Jan 15 2025 Now-Tonight...Mid and high level clouds are streaming west to east across the Florida Peninsula this afternoon as temperatures slowly climb into the mid 50s (north) to upper 60s (south). It has also been a little breezy, with northerly winds gusting 20-25+ mph at times along the immediate coast. RAP analysis indicates a fairly tight pressure gradient over the area, but this should unwind tonight, allowing wind speeds to decrease. Radar returns are very light at this time, with broken bands of 20dBZ or less traversing the state. Most of this activity is struggling to reach the ground, evidenced well by the very dry low levels in this morning`s XMR sounding. Another night of below normal temperatures is forecast with the coldest spots north of I-4 by early Thursday morning. However, with cloud cover expected to blanket the area, forecast lows are up to 5 degrees warmer compared to temperatures we experienced this morning. Thursday-Friday...Lighter winds and minimal precipitation are forecast to end the work week, but temperatures will stay below normal for mid-January. High pressure stays in place during this timeframe, while northwest 500mb flow on Thursday becomes quasi- zonal on Friday. A cool start on Thursday gives way to cool afternoon temperatures, ranging through the 60s areawide. Some clouds may linger near the Treasure Coast Thursday night into Friday, but many locations (especially north of I-4) will become mostly clear. Calm and clear conditions will allow for efficient radiational cooling to take place, dropping temperatures into the upper 30s over northern Lake/Volusia counties, with values ranging through the 40s to low 50s over the remainder of the area. A mostly clear to partly cloudy sky on Friday will do very little to help temperatures recover, staying slightly below normal Friday afternoon. Saturday-Sunday...A significant warmup and more active pattern returns to the area this weekend. For those looking to get outside and take a break from long sleeves and jackets, highs in the 70s to low 80s are forecast each day. A broad longwave trough is set to move across the Lower MS Valley and central Gulf Coast Saturday morning as a warm front lifts north of Florida. As return flow quickly increases, so does moisture. Anomalously high PW surge across north-central Florida Saturday afternoon, supporting an increase in shower activity through the day. Locations near and north of the Orlando metro to Cape Canaveral look best situated to receive measurable rainfall Saturday afternoon and evening. Likely rain chances expand to the remainder of the area on Sunday as a strong cold front pushes south. Models have swung back and forth with regard to available MUCAPE on Sunday, but have decided to include a low chance of thunder Sunday afternoon, mainly from the Orlando area to points south. Throughout the weekend, winds will be breezy to gusty at times as the pressure gradient strengthens ahead of the front. Temperatures plummet Sunday night into early Monday as colder and drier air dig south. Next Week (previous)...An active pattern is forecast to continue into early next week. Models continue to disagree on the exact setup. However, the bottom line appears to be that shower chances will continue, though the amount of showers is in question. Onshore flow looks to develop, producing breezy conditions along the coast. Temperatures are forecast to remain cool, but nearer to normal than the previous few weeks. && .MARINE... Issued at 300 PM EST Wed Jan 15 2025 Winds...Gusty north winds this evening will gradually decrease tonight, with speeds 10-15 kt expected on Thursday. Northwest winds briefly increase to 15-20 kt offshore Thursday night, slackening on Friday to 10 kt or less. Surface flow then shifts to the south on Saturday, reaching 15-25 kt. Winds veer increasingly west- southwest by Sunday as a cold front moves across the waters. Seas...Waves up to 6 ft in the Gulf Stream remain possible through tonight before a generally favorable period of boating conditions Thursday through early Saturday morning. As winds increase Saturday, seas build (especially offshore) up to 6 ft. Episodes of poor to hazardous boating conditions will be possible from this weekend into early next week, mainly in the offshore waters. && .AVIATION... (00Z TAFs) Issued at 649 PM EST Wed Jan 15 2025 VFR conditions forecast to continue tonight into Thursday. Higher cloud deck with cigs at or above 15kft will lower to around 7-9kft into tonight through Thursday morning. Passing shortwave aloft may lead to some light rain/sprinkles developing with these clouds overnight into early Thursday, but MVFR impacts from this activity look unlikely. Winds will initially be out of the north and becoming light (5 knots or less) into tonight. An increase in northerly winds to 7-10 knots is forecast toward daybreak Thursday, before weakening again into the afternoon and directions becoming more variable. && .FIRE WEATHER... Issued at 300 PM EST Wed Jan 15 2025 Near-critical minimum relative humidity values are forecast through late week, especially on Friday, as drier air builds over east central Florida. Winds will remain light and variable (generally less than 10 mph) on Thursday, veering east-northeast on Friday. && .PRELIMINARY POINT TEMPS/POPS... DAB 44 62 40 63 / 20 20 0 0 MCO 49 63 45 67 / 10 10 0 0 MLB 49 64 44 66 / 10 10 0 0 VRB 52 68 47 69 / 10 10 10 10 LEE 45 63 42 67 / 10 10 0 0 SFB 46 64 42 67 / 10 10 0 0 ORL 48 64 44 67 / 10 10 0 0 FPR 51 67 46 69 / 10 10 10 10 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ UPDATE...Weitlich AVIATION...Weitlich
Area Forecast Discussion
National Weather Service Marquette MI
537 PM EST Wed Jan 15 2025 .KEY MESSAGES... - A clipper low will bring a quick batch of light snow (1-2 inches) for most of the UP this evening through the first half of the night. Lake effect snow lingers in the west to northwest wind belts the second half of the night. Another 1-3 in of snow is expected in those wind belts, with lighter totals mainly of an inch or less across the rest of the UP. - SW gales of 35-40kts continue the west half of Lake Superior this afternoon, ending by midnight Thursday. - Dangerously cold arctic air settles into the area this weekend into early next week, leading to temperatures remaining subzero Saturday night through at least Tuesday morning over interior western Upper Michigan. - While winds won`t be strong, whiteouts will be common in the areas affected by northwest flow lake effect snow showers Saturday through Monday due to the snow being a fine, powdery type snow. As a result, travel conditions will be very hazardous in the lake effect snow areas. - No widespread, significant snowfalls for Upper MI through next week. Nearly all of the snow that occurs will be lake effect driven. && .SHORT TERM /THROUGH THURSDAY/... Issued at 317 PM EST Wed Jan 15 2025 Afternoon RAP analysis and water vapor imagery depict a clipper system diving southeast into the Upper Great Lakes with associated isentropic lift kicking off snow showers in central Minnesota. As the shortwave nears closer to home, these showers will continue their eastward march into the UP, eventually reaching the far west this evening before exiting quickly to the east before sunrise tomorrow morning. Not expecting any heavy snow accumulations with these passing "system" snow showers tonight as guidance only suggests light QPF generally <0.1" tied with SLRs in the upper teens:1, yielding light snow across the UP 1-2" or less through tonight. Behind the cold frontal passage early Thursday morning, winds veer to the northwest and 850mb temperatures above Lake Superior lower between -10 to -13C, supporting light lake effect snow for the NW snowbelts. Lake effect snow will be short lived, however, as a brief period of ridging aloft and drier air works its way in across the lake Thursday afternoon, lowering inversion heights and tapering off LES from west to east. Considering light QPF and fluffier SLRs closer to 20:1, an additional 1-3" is possible across the Keweenaw and NW snowbelt between Munising and the Soo. Otherwise, southwest winds overnight will keep temperatures mostly above 10F tonight, much warmer than the past few nights. High temperatures tomorrow are expected to remain in the mid to upper 20s, possible closer to or above freezing near Lake Michigan. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... Issued at 443 PM EST Wed Jan 15 2025 Medium range model guidance is in excellent agreement on a large scale surge of arctic air into the U.S. this weekend into early next week. This will be driven by a building ridge over the ne Pacific that becomes highly amplified northward thru Alaska/nw Canada into the high Arctic over the weekend, forcing a significantly deepening trof downstream across central to eastern N America. Negative height anomalies at 500mb in this trof settle at about 300m (2-2.4 sigma) over WI and Upper MI Sun night. Thus, the large scale surge of arctic air southward into the U.S. Over the last 48hrs, ensembles have slightly lowered 850mb temps in the core of the cold air as it reaches Upper MI. Median 850mb temps reach -30 to -31C into western Upper MI for Sun/Mon with Mon likely the coldest day. 850mb temps that low at this time of year very easily support 2m temps remaining subzero during the daylight hrs across interior western Upper MI and likely thru much of central Upper MI as well. Now, with 850mb temps forecast to be down to -30C or lower, would expect temps during the daylight hrs over interior western Upper MI to struggle to get above -10F Sun/Mon, Mon in particular. Once temps fall blo 0F over interior western Upper MI Sat night, they won`t rise above 0F until sometime Tue aftn at the earliest. Min temps will range down thru the negative teens and -20s F away from Lake Superior. Some record low min and record low max temps may be set across Upper MI with this arctic outbreak. Homeowners and property managers who have had issues with water pipes freezing during periods of very cold conditions should make preparations now. Areas that have very little snow cover could also become at risk for freezing of water supply lines early next week as ground frost depths deepen rapidly. As for pcpn, this pattern will not support any widespread, significant snowfalls for Upper MI for the remainder of this week and through all of next week as only a few clipper type waves will generate some brief periods of -sn. So, snowfall will be almost exclusively lake effect driven. While the arctic air arriving over the weekend/early next week will lead to extreme overlake instability, the cold will also suppress the DGZ toward the sfc or eliminate it altogether, leading to a fine/powdery type snow (low SLR) that does not accumulate as efficiently. On the flip side, this type of snow is highly effective at reducing vis, leading to frequent whiteouts even with winds not particularly strong/gusty. This type of snow is also easily kicked up on roads by vehicles, leading to mini whiteouts as vehicles pass each other. Travel in the areas affected by nw flow LES Sat thru early next week will be very hazardous due to poor visibility. From Tue onward, flow across N America deamplifies, but there will continue to be ridging in the ne Pacific/adjacent N America forcing troffing in central and eastern N America. The deamplification will allow for moderation Tue onward, but the pattern will still support the potential for colder air to at least graze Upper MI with the passage of clipper type shortwaves. Expect temps on most days next week to be blo normal. Beginning Thu night/Fri, a clipper shortwave will track vcnty of the International Border and will pass across Upper MI Fri night. This wave will initiate the start of the arctic air surge. WAA/isentropic ascent will need to overcome drier air. With bulk of guidance suggesting sufficient saturation occurring deeper into the retreating colder air where it is easier to achieve, forecast only reflects mainly chc pops from the Keweenaw into eastern Upper MI, beginning very late Thu night over the Keweenaw and spreading to the e quickly Fri morning. Any snow accumulation will be less than 1 inch. Center of pres falls of 6-7mb/3hr passing just n of Upper MI on Fri will enhance s to sw sfc winds on Fri. Expect gusts of 25 to 35mph. Downsloping near Lake Superior may yield gusts of 40-45mph for a few hrs from Marquette County eastward per fcst soundings. 180- 190 wind direction is favorable for strong winds in Schoolcraft/Luce counties as well. High temps on Fri should reach the low/mid 30s F. Cold front passes Fri night, initiating LES and leading to progressively colder air flowing into the area thru the weekend on predominantly nw low-level flow. The increasingly colder air surrounding the lake will progressively strengthen lake induced thermal troffing, leading to winds developing an offshore component. This will be more notable off of nw WI, off of Marquette County and off of Ontario along the e side of Lake Superior. This will favor enhanced convergence from n of Ironwood into Ontonagon/southern Houghton counties and also into Alger/Luce counties. Expect LES to be most persistent/heavier in those areas. However, by later Sat and thru Mon, the cold will suppress the DGZ toward near the sfc or eliminate it altogether, leading to a fine/powdery type snow that does not accumulate as efficiently as typical LES. Initial thoughts are that snow accumulations will end up in a general 1-3 to isold 4- 5 inches/12hr range. Bigger issue will be whiteouts as this type of snow is highly efficient at reducing visibility and is easily blown around. Winds will be stronger on Sat after fropa, but during the coldest period Sun/Mon, winds won`t be particularly strong, gusting to 25 to at times 30mph near the Lake Superior shore and Keweenaw and up to around 20mph elsewhere. Even so, the fine/powdery snow will be easily lofted by these winds to further reduce the already poor vis from the falling snow. As for temps, max temps in this fcst issuance are probably a bit on the high side for Sun/Mon given how low the 850mb temps will be. It`s quite plausible that high temps will struggle to get above -10F over much of the interior w on Sun/Mon, Mon in particular. Much of the fcst area may remain blo 0F both days. Fortunately, the winds won`t be strong to really drive wind chills down. Nonetheless, the cold will be dangerous, and expect conditions to warrant cold weather advisories and possibly extreme cold warnings across the area. Extreme cold warning criteria are air temps or wind chill -35 or lower over interior western Upper MI and -30 or lower elsewhere. Wind begin to back westerly Mon night/Tue with onset of waa, shifting LES to mainly the Keweenaw over the w and closer to shore over the e. Clipper type shortwave will pass at some point later Tue/Wed to provide a chc of -sn. High temps will be back to the teens F on Wed. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 537 PM EST Wed Jan 15 2025 Clipper system snow will move through the area tonight and will take the VFR conditions down to IFR as it moves through at all sites. MVFR conditions will reutrn to all sites Thu afternoon. && .MARINE... Issued at 443 PM EST Wed Jan 15 2025 A couple of passing clippers will result in a strong pressure gradient over the lake at times in this period, followed by deepening arctic cold this weekend and early next week. Ongoing sw 35-40kt gales over the w half of Lake Superior will fall back to 30kt tonight as winds shift w to nw. Expect winds up to 30kt over the e with a few gale force gusts possible during the evening. The nw winds will increase across the e half of Lake Superior on Thu morning. Expect gale gusts to 35kt for a time morning thru early aftn. Probability of gales is 40-60pct. Winds briefly settle down to around 20kt lakewide Thu evening as high pres ridge quickly passes. Winds then increase as the next clipper approaches. Enhanced by pres falls passing eastward over and n of Lake Superior, s to sw winds will ramp up to 35-40kt gales over much of Lake Superior, strongest over the e half. The potential of winds to reach high end gales is 25-45pct over the e half of the lake. These winds will shift to the nw Fri night. Aided by incoming pres rises and colder air, expect gales of 35-40kt across central and eastern Lake Superior into Sat morning. Very cold air pouring over the Upper Great Lakes afterwards and lingering into next week will likely support winds of 25-30kt across much of the lake. The increasingly colder air arriving over weekend will support periods where ice growth from freezing spray will become mdt to hvy at times. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning until 10 PM EST /9 PM CST/ this evening for LSZ162. Gale Warning until 1 AM EST /midnight CST/ Thursday for LSZ241>244-263-264. Gale Watch from Friday morning through Saturday afternoon for LSZ241>244-263-264. Gale Watch from Friday morning through Saturday afternoon for LSZ249>251-266-267. Lake Michigan... None. && $$ SHORT TERM...BW LONG TERM...Rolfson AVIATION...07 MARINE...Rolfson