Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/30/20

Area Forecast Discussion
National Weather Service La Crosse WI
601 PM CST Wed Jan 29 2020 .SHORT TERM...(Tonight through Thursday Night) Issued at 137 PM CST Wed Jan 29 2020 Current GOES water vapor/RAP 500mb analysis showing a trough of low pressure passing through the region. RAP showing best pv- advection/lift for light snow will stay south of the area through the rest of this afternoon. Otherwise, another cloudy day with temperatures as of 1 pm in the 20s. A ridge of high pressure builds into the area tonight, but don`t plan on any clearing as moisture remains trapped under the subsidence inversion. May have to keep an eye on some fog development as well with very weak surface flow and ambient moist conditions. HREF showing a 60-70 percent probability of 1 mile or less visibility after midnight across northeast IA into central WI. Bufkit soundings however maintain a couple degree separation in T/Td lending to lower confidence in widespread dense fog. However, if dense fog does form, could see some slick roads in addition to the reduced visibilities, especially bridges and overpasses. Will keep a close eye on it. Thursday looking cloudy once again between departing high pressure and approaching trough of low pressure from the Northern Plains. Plan on highs in the 25 to 30 degree range. Another trough of low pressure moves into the region Thursday night. Fairly decent amount of mid-level pv advection and lower level isentropic lift indicated by the models for a shot of some light snow. Looks pretty light though with generally 1/2 inch or less anticipated. May have to watch for some patchy freezing drizzle at times as model soundings showing occasional loss of ice in cloud. Could make for some impact on the Friday morning commute. Otherwise, looking for lows in the upper teens to lower 20s. .LONG TERM...(Friday through Wednesday) Issued at 137 PM CST Wed Jan 29 2020 Light wintry mix of freezing drizzle/snow still possible Friday/Friday night in lingering cyclonic flow/lift. Highs look to be in the upper 20s/lower 30s. Large ridge of high pressure builds in Saturday into Sunday. This will lead to quiet conditions with moderating/mild temperatures. Look for highs Saturday in the 30s and in the upper 30s to mid 40s Sunday. The ridge starts moving east of the area Monday as a major trough develops over the Intermountain West. Looks dry for now with push of moisture/chance of precipitation remaining just south of the area. Light snow chances move in Monday night lasting into Tuesday as the mid-level trough progresses east through the central CONUS. Cooling temperatures will also be noticed with highs Tuesday falling back to near normal levels in the 20s. Wednesday is looking dry as the trough pushes east of the region and weak high pressure fills in behind. Highs will be in the teens to mid 20s. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 600 PM CST Wed Jan 29 2020 A shallow layer of low level moisture remains trapped beneath high pressure sitting over the region, so low stratus will persist through the period. A few flurries possible this evening. Ceilings will decline this evening, becoming IFR at RST with LIFR likely overnight, while LSE will drop from MVFR to IFR late. In addition, there are fairly strong model signals for fog developing tonight, particularly at RST. Confidence is high for fog occurring at RST, the only questions being how low visibility will drop and when this will occur. Have introduced tempo 1/2SM from 09-12Z, but expect it could go lower given the 1/4SM that occurred this morning. Visibility reductions not as likely at LSE, with most models showing the fog staying just off to the north and west, so have gone with unrestricted visibility there for now. Will monitor trends through the evening. Visibility will gradually improve towards mid-morning at RST, and expect a slow, very subtle rise in ceilings in the afternoon. Light and variable to calm winds overnight will become more southerly on Thursday. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...Kurz
Area Forecast Discussion
National Weather Service Denver/Boulder CO
806 PM MST Wed Jan 29 2020 .UPDATE... Issued at 806 PM MST Wed Jan 29 2020 Convective snow showers continue to move SSE across our area. Radar is tracking them well across the south and southeast sides of metro Denver. Webcams and social media show large, wet flakes for 10-20 minutes resulting in a dusting on the grass. Further northeast across southern Weld and Morgan Counties, just some light snow for the next few hours that will also move off to the southeast. Roads remain wet given road temperatures in the mid 30s even after snowfall, and air temperatures between 30-33. There is a sharp cutoff to the convective forcing, and for the most part the HRRR has the cutoff well handled. Larimer/Boulder and the northern 2/3 of Weld Counties are likely done for the evening, with the cutoff moving southeast throughout the evening. Overall coverage is spotty given the nature of the convection, so some places in the metro area and the plains northeast and east of Denver may not see any flakes. The showers should be south of Denver across the Palmer Divide across Elbert and Douglas Counties by 10 PM, then out of our area to the south and southeast by midnight. Dropped PoPs for the northern third of our area given the showers have already moved south of those areas, then reduced them gradually to the south to reflect dry conditions after midnight. Across the mountains, web cams and radar have not indicated much if any shower development, so will drop PoPs after midnight when the moisture across the west slope weakens. Any additional accumulation through midnight will be light, if any. The rest of the forecast looks on track, including for convective showers again tomorrow though instability and moisture look a bit less than today, resulting in weaker showers and even less coverage across the plains. Plains east of I-25 and northeast of the Palmer Divide will likely be dry. The mountains may see a little bit more activity with better west- northwest upslope flow, but amounts should remain light given the poor lapse rates. && .SHORT TERM...(This evening through Thursday) Issued at 245 PM MST Wed Jan 29 2020 An upper low has dug down into southern Arizona with its associated trough stretched northeast across northwestern and northern Colorado. Some clearing in the clouds over the forecast area has allowed temperatures to warm and some convective clouds to form. As upward QG motion is increasing ahead of the upper trough, and the expected weak cool front will push down southeast across the area, snow showers will be increasing in coverage and intensity across the mountains and down into the plains. The mountains may see up to 3 inches, with the larger amounts mainly along and south of I70. Across the plains, with the warmer temperatures of today and sunlight warming the ground, scattered snow showers later this afternoon and into the evening should produce little accumulation. However, with the showery nature, as well as the northerly winds, expect to see localized areas near the Palmer Divide to see upwards of up to 3 inches. Downward QG as well as a lee side surface low developing after midnight will quickly dry the atmosphere out with decreasing PWs and drainage winds forming. Skies will clear out, allowing for the high mountain valleys to likely get down to near zero degrees, while winds becoming gusty along the foothills will keep temperatures in the 20s there and into the urban corridor. The next system will drop out of Canada in the northwest flow aloft with a jet speed max. Snow will push into the mountains by late morning, with a stronger cold front pushing down the plains by early afternoon. The northerly winds will again bring a chance of snow over the Palmer Divide first by late afternoon while the rest of the plains should remain mostly dry before the airmass moistens up better in the evening. .LONG TERM...(Thursday night through Wednesday) Issued at 245 PM MST Wed Jan 29 2020 A north-northwest flow aloft will prevail over Colorado Friday while a ridge builds along the California coast. This is expected to bring dry conditions to the area. A little warm air advection will occur, so expect slightly warmer temperatures Friday with highs in the mid 40s to lower 50s over northeast Colorado. The upper level ridge will advance across the Central Rockies this weekend ahead of an upper level trough over the Pacific Northwest. Warm and dry conditions are expected under this pattern Saturday and Sunday. The GFS model is about 12 to 24 hours faster than the Canadian and ECMWF models with the approach of the upper level trough from the Pacific Northwest. If the GFS pans out, a strong cold front will drop south across eastern Colorado during the day Sunday and produce falling temperatures. Believe the other models that the cold front will arrive Sunday night and Monday morning. Will keep highs in the 60s for Saturday and Sunday across northeast Colorado. Could even see a few low 70s on Sunday. For next week, an upper level ridge will build along the west coast of North America. This will result in northwest flow aloft along the Rockies and allow cold air to surge south. The trough over the Pacific Northwest will travel southeast and strengthen Monday. Models still trying to figure out how far south the trough will dig and if it will strengthen into a closed low. Despite the uncertainties with the evolution of the trough, cold temperatures and snow are very likely sometime late Sunday through Tuesday. Biggest question marks are the timing and strength. Highs Monday and Tuesday are expected to be near to below freezing. Tuesday is expected to be the coldest with highs in the 20s over northeast Colorado. Will have likely PoPs in the forecast for Monday and Monday night when the best chance for snow will be. Northwest flow aloft will prevail behind the exiting upper level low/trough. This will keep temperature cool. Good chance that snow showers will continue in to the mountains under this pattern while it dries out across the lower elevations. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 806 PM MST Wed Jan 29 2020 A few convective snow showers will continue through 9 PM or so at DEN and APA. Current radar trends show the showers splitting DEN right now, but can`t rule out some light snow filling in the gaps between showers through 9 or 930PM. APA will get some snow, enough to briefly slush the runway before it melts off with the still warm runways. BJC should miss out on any snow. CIGs and VIS should remain MVFR at DEN and APA even with some snow. After midnight conditions should return to VFR and remain that way through Thursday. Winds will briefly remain north to northeast through about midnight before coming around to the south at DEN and APA, W at BJC. Winds will again shift to N on Thursday, and gust to 25 kts at DEN by mid afternoon. There is a slight chance of a convective shower in the late afternoon/early evening, most likely snow, at the terminals but the chance is too low to include in the TAFs at this time. We are talking 5-15% at most, with the best chance at BJC and APA. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Schlatter SHORT TERM...Kriederman LONG TERM...Meier AVIATION...Schlatter
Area Forecast Discussion
National Weather Service Grand Forks ND
922 PM CST Wed Jan 29 2020 .UPDATE... Issued at 916 PM CST Wed Jan 29 2020 Still chasing first band of very light mixed precip across the forecast area this evening, with second batch on track through early Thursday. NAM and RAP both consistent in pushing second band through eastern ND Thursday forenoon and out of northwest MN through mid afternoon. UPDATE Issued at 623 PM CST Wed Jan 29 2020 Light freezing mist in the area otherwise no significant changes to the forecast package. An updated Aviation Discussion is attached below. && .SHORT TERM...(This evening through Thursday night) Issued at 312 PM CST Wed Jan 29 2020 Current water vapor imagery along with radar indicates a weak upper wave with associated light snow across northwest Minnesota. Visibility with this light snow is 1-2 miles, and is leading to a bit of accumulation (up to 0.5 inch). Mid-upper layers are saturated enough for ice nuclei introduction with this forcing. This high PoP/low QPF scenario will move east by this evening. Behind this upper wave, light winds and near saturated low level airmass is leading to areas of fog (not dense) and freezing drizzle (light mist). Anticipate this entire pattern will continue to shift east (along with light winds and lowering vsby/fzdz). Fargo is now reporting freezing drizzle. Most reports indicate this freezing drizzle is leading to windshields icing up, with most parking lots/roads not much impacted. With that said, have received a report or two of icy roads/sidewalks. Impacts do not currently seem enough to warrant a winter weather advisory, but will monitor. With that said, water vapor shows the next upper wave upstream that will affect the region tonight. Upper level trough slowly propagates through the region tonight into the day on Thursday. RAP and a few CAM solutions indicate QPF this evening into Thursday. Current observations upstream in Canada are freezing drizzle. Mid-levels do dry out so freezing drizzle does become more likely where precipitation does occur. Will issue an SPS to cover the possibility of impactful freezing drizzle tonight and also to increase awareness for the current freezing drizzle situation. .LONG TERM...(Friday through Wednesday) Issued at 312 PM CST Wed Jan 29 2020 Friday: Seasonal temperatures persist ahead of a longwave ridge building in through the weekend. Light southwesterly winds will be present throughout the afternoon, leading to slight warm air advection and moderation of radiative cooling the the overnight hours. Pockets of fog and possibly light snow can`t be ruled out early Friday morning. Saturday-Sunday: An upper-level ridge moves into the region early in the weekend, bringing a more westerly component to the wind. Compressional heating off of the Rockies will lead to widespread temperatures well above normal across the region. GEFS members show good agreement on highs for both days in the mid to upper 30s with a few low 40s possible for the Devils Lake Basin on Saturday. Overall, the weekend will be dry with a few breaks in the clouds possible near the Canadian border. Monday-Thursday: Chances for light snow return Monday with the passage of an Arctic cold front. Significant impacts are not expected with this event, but another dusting of snow is possible, along with a return to colder temperatures in the teens for highs. As the front moves east, sustained winds in the Western RRV could be in the 20-25 kt range, but partial melting over the weekend makes blowing snow impacts unlikely. Yet another minor snow chance returns late next week as a shortwave trough looks to move south out of Canada. Again, little impacts are expected at this time, but some disagreement in GEFS members is present so stay tuned. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 623 PM CST Wed Jan 29 2020 Main concern continues to be prevalent LIFR to IFR cigs and patchy freezing drizzle or mist throughout the evening and overnight periods. A first area of light freezing drizzle will move across from the Red River Valley corridor and across northwest MN through 03z this evening. A second batch will move across eastern ND into the RRV from about 04z through 08z tonight... and continue eastward across northwest MN from 07z through 12z. Ceilings are expected to lift into IFR range for daylight hours on Thursday. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...Gust SHORT TERM...TG LONG TERM...AM/DD AVIATION...Gust
National Weather Service Hastings NE
541 PM CST Wed Jan 29 2020 .SHORT TERM...(This evening through Thursday Night) Issued at 412 PM CST Wed Jan 29 2020 Today has turned out to be quite a bit nicer than previously expected. The fog did not materialize on a widespread basis and low stratus has steadily shifted E with time today. This has allowed hi temps to exceed expectations, and are currently running in the upper 30s to mid 40s, warmest across W portions of the CWA where sun has been most persistent and snow cover is limited. Looking at the upper levels, flow is quite messy across the CONUS with several shortwave troughs embedded in the flow. One wave was shifting E of the MS Valley while our next wave is strung out from the Dakotas down to a stronger vort max over the Desert SW. Yet another wave can be seen moving onshore W Canada. This leaves shortwave ridging over the local area this aftn. The later waves will try to impact our wx over the next few days, but will likely be limited to mainly cld cover and wind shifts. The main issue in the short term is the potential for low stratus and fog again tonight. Given the lack of fog last night, my feeling is that tonight will not be too bad given the added wind and clds. High clds are already on the incr ahead of the Dakotas- Desert SW trough, and these will likely only incr further/thicken this eve. Current satellite reveals the W edge of the stratus is just barely outside our CWA, so it won`t have far to return this eve as the ridge axis shifts E and return flow sets up. However, H95 RH analysis off the RAP shows a gap of high RH over our CWA tonight, and this lines up nicely with the ongoing gap in stratus from near OLU to HYS. So tonight may be a situation where NE/E portions of CWA sees some stratus return out of OAX CWA, as well as the far S, with a gap over the central CWA. We`ll see. To further complicate matters, the BL will have some added moisture due to modest snow melt from this aftn. As it stands now, hi-res models are not too excited about widespread dense fog, and this seems reasonable given the aforementioned factors. Going forecast has patchy-areas of fog, and this may be too much, esp Thu AM as the trough axis will shift winds to the SSW/SW. This portion of forecast is low confidence, and eve shift may have to adjust. As the two troughs swing through, some models indicate some very lgt QPF tonight and again Thu night. The lift tonight is very modest, and forecast soundings show persistent dry layer between H8-H7. Lift as well as saturation is slightly better Thu night as the main trough axis moves through. Models have hinted at lgt QPF just N of the CWA for several runs now, so have inserted some slight POPs across far N/NE CWA to account for this. Don`t expect anything measurable attm. Temperatures tonight & Thu night should remain seasonable in the 20s. Bumped up Thu highs a couple deg, mainly for the W half or so, as these areas bounced nicely in the sun this aftn. These areas have least potential for clds and will have a Wrly/downsloping component to wind during peak heating on Thu. .LONG TERM...(Friday through Wednesday) Issued at 412 PM CST Wed Jan 29 2020 The main story in the extended is the rise in temps for the weekend, followed by drop and chance for snow early next week. Upper flow will amplify late this week and over the weekend as a ridge builds over W CONUS and shifts E. The greatest ridging looks to be in place Sat night into Sun. Flow then becomes SWrly Sun night into early next week as a pair of troughs move into W CONUS, one in the N stream across Intermountain West, and another in the S stream near southern NM. Differences arise between the GFS/EC by Sun, namely in the speed/timing of these troughs. Both models keep these troughs unphased, but will be interesting to see if this continues. The biggest differences come in the timing of the front Sun. The GFS is 12-18hrs faster than the EC, but has been lacking some consistency. The EC has been much more consistent, and the mean, in fact, has risen a deg or two across the area. The official blend came down a couple deg, likely due to the GFS, but given the consistency and low spread on the EPS, expect these will likely rise yet again. For reference, the latest EPS gives a high of 65F for HSI vs the current official forecast of 57F. Assuming the EC is correct, this weekend looks VERY pleasant considering we`re near the climatologically coldest time of year. Winds don`t look very strong either. EC/GFS are in good agreement that the lead wave (likely the S stream trough) doesn`t quite get its act together in time to produce meaningful QPF Sun night into Mon as it remains unphased with the N stream trough that remains further W. If phasing were to incr there could be a significant storm system across the central CONUS. However, appears the more likely scenario attm is for the N stream trough to come out Mon night into Tue and provide lift back over the cold air, well N of the low level baroclinic zone, and produce a swath of snow. Where exactly this sets up remains to be seen, but the potential for some light to moderate snow is there in the Mon night to Tue time frame. Temps will be sharply colder for Mon-Tue, but not too bad for time of year. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Thursday) Issued at 527 PM CST Wed Jan 29 2020 MVFR stratus has already crept into KGRI and expect it to overtake much of the region during the late evening through overnight hours. This stratus will be accompanied by some light BR...but kept VSBYS in the MVFR range at both terminals as the denser fog should be either well south or well northeast of both sites. Otherwise...stratus will likely lower to near IFR levels by around 30/06z...remaining at those levels through the early morning hours Thursday...before improving to MVFR levels by afternoon. Overall...a stratusy forecast with light southerly to southwesterly winds prevailing. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...Thies LONG TERM...Thies AVIATION...Rossi
Area Forecast Discussion
National Weather Service North Platte NE
626 PM CST Wed Jan 29 2020 .UPDATE... Issued at 602 PM CST Wed Jan 29 2020 Day Snow-Fog and then NtMicro RGB imagery with our decreasing sunlight shows fog/low stratus across the easternmost counties has advanced west and now covers all of Holt and Boyd counties. KONL as well continues to report visibility <1/4SM persistently with web cams showing evidence of fog across the area also. Meanwhile, latest guidance including GLAMP, ADJLAV, NBM, and HRRR continue to support the likelihood for dense fog continuing at times tonight-early morning. While there may be a short reprieve with improving visibility at some point, thinking redevelopment is likely shortly thereafter as hydrolapse becomes favorable again tonight and winds slack off based on latest RAP soundings. Thus a dense fog advisory was issued for Holt, Boyd, Garfield, and Wheeler counties. Will continue to monitor the situation as we may need to add additional counties. && .SYNOPSIS... Issued at 320 PM CST Wed Jan 29 2020 H5 analysis from this morning remains active across the central and western CONUS. A shortwave trough extended from Minnesota south into northern Louisiana. Upstream of this feature, a weak disturbance was located over eastern Wyoming. This feature has spread abundant high cloudiness across the forecast area this afternoon and even snow to portions of the western and southwestern Nebraska Panhandle. Upstream of this feature, a trough of low pressure extended from northern Utah into swrn Arizona. At the surface skies were mostly cloudy this afternoon and some fog was present over far northeastern portions of the forecast area. This area of fog has been very persistent today. Visibilities should improve some this afternoon per the HRRR, but fog will remain a threat into the afternoon hours. Temperatures as of 2 PM CST, ranged from 32 at O`Neill to 46 at Thedford. && .SHORT TERM...(This evening through Thursday night) Issued at 320 PM CST Wed Jan 29 2020 The main forecast issue tonight is fog potential in the east. As mentioned above, fog has been very persistent in the far northeastern forecast area this afternoon. Based on the HRRR, visibilities should improve marginally this afternoon. With sunset, fog is expected to develop once again per the HRRR and SREF ensembles. As for forecast visibilities, confidence in retaining a quarter mile or less overnight is in doubt. A broad shield of mid and high clouds will continue to stream in from the west overnight in association with the shortwave over eastern Wyoming. Fog potential continues to remain high in the eastern forecast area tonight, however based on the expected abundance of mid and high level clouds not overly confident in visibilities of a quarter mile or less. After coordinating with FSD and OAX, will forgo issuance of a dense fog advisory for now as confidence in quarter mile visbys is only low to moderate at this juncture. On Thursday, some limited will develop behind the exiting shortwave trough. Skies will then cloud up late afternoon into Thursday evening as a second, stronger shortwave trough approaches the central and southern plains. Lift will be decent with this feature, however, available moisture is meager and will limit QPF`s and snow potential Thursday night. ATTM, based on the latest NAM12 and GFS solns, the best chances for snow will be over north central Nebraska. In these areas, based on a qpf forecast of around 0.05 inches, will limit any snow accumulations to an inch or less. .LONG TERM...(Friday through Wednesday) Issued at 320 PM CST Wed Jan 29 2020 Friday through Sunday continues to look tranquil as ridging aloft builds into the western CONUS, then east across the Plains. This ridging will quickly become flattened by a strong Arctic shortwave trough Sunday. As this feature traverses Canada into the western CONUS, it will force an arctic cold front through the forecast area on Sunday. For Friday and Saturday, temperatures will climb form the 40s Friday, to the 50s and 60s for Saturday. Frontal timing for Sunday is really problematic. The GFS and Canadian are quicker with the cold front, passing it through the forecast by 18z Sunday. The ECMWF is much slower, passing this feature through the forecast area by 00z Monday. No surprise, there is a large difference between the MEX and ECM guidance for highs Sunday and the latest NBM today has trended temps down 5 to 7 degrees from the pvs forecast. Feel this forecast is a good compromise between the three model solns. In addition, the ensemble members for the GFS from this morning are indicating the operational GFS being toward the faster side of the ensemble members. So in effect, taking an ensemble mean of the GFS slows the front down more toward the ECMWF soln. Beyond Sunday, much colder temperatures will settle into the region. Highs Monday and Tuesday will be in the 20s to 30s with a slight warmup to the 30s and 40s for Wednesday. Both the ECMWF and GFS solns do develop a broad area of post frontal, mid level frontogenesis induced, snowfall Monday into Tuesday. Will highlight this in the HWO as the threat for accumulating snow appears decent. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 554 PM CST Wed Jan 29 2020 Fairly quiet aviation conditions expected at both terminals through the next 24 hours. Some patchy dense fog is expected across north central Nebraska. Fog is expected to remain east of both sites and not expected to cause any impacts at either airport. VFR conditions will continue through Thursday. && .FIRE WEATHER... Issued at 320 PM CST Wed Jan 29 2020 We are still monitoring the fire weather threat for Saturday and Sunday across the forecast area. The threat for critical fire weather has decreased some for Sunday as two mid range forecast models, push a strong cold front through the forecast area by midday. If the front were to slow down, critical or near critical minimum relative humidity could be seen in SW Nebraska Sunday afternoon. && .LBF WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory until 8 AM CST Thursday for NEZ007-010-028- 029. && $$ UPDATE...ET SYNOPSIS...Buttler SHORT TERM...Buttler LONG TERM...Buttler AVIATION...Kulik FIRE WEATHER...Buttler
Area Forecast Discussion
National Weather Service Marquette MI
650 PM EST Wed Jan 29 2020 .SHORT TERM...(This evening through Thursday) Issued at 318 PM EST WED JAN 29 2020 RAP analysis indicates a weak flow pattern across the region, with a 1029 mb high over James Bay and the tail end of a weak surface stationary boundary draped across the UP. Cloud shield evident in GOES16 Vis and WV imagery extends from the northern edge of Lake Superior south into the Tenn River Valley. Through the short term, the pattern won`t change much: the high over James Bay will shift S- SE over the Ontario/Quebec border, and a weak upper level shortwave will move through the region Thursday Morning, followed by more weak ridging. Overall pattern hasn`t changed much through the day, except for drying out at the surface across the region, which cleared out this morning`s -FZDZ. Models had a hard time picking up on it and forecasts relied heavily on surface obs and persistence forecasting. Confidence this afternoon isn`t very high given the hard time models had today, but the low level dry air should limit any precip from reaching the ground. If any does, given saturation as high as 3-4k feet and lack of consistent temperatures within the ice growth zone, it`ll mainly be in the form of -FZDZ with the potential for some snow flakes to mix in. The winds will be light and variable for the most part. Tonight into the early morning, a weak upper level trough will swing east through the region. Some models suggest more of a meso-low feature while others, namely the NMM/ARW suggest more of a banded structure. These same CAMS are more aggressive with the QPF, but given the model spread on the location and the amounts sfc-850 directional shear, kept POPs slight to chance. Either way, models are consistent with this feature moving into the Manistique/US-2 in the morning hours. QPF should remain light, so accumulations shouldn`t be a concern, but because the timing looks to be around the morning commute, some snow on the roads could cause some slick spots around Manistique or along US-2. Tomorrow, as the flow remains out of the south, I kept a chance of snow in the forecast for this feature. Elsewhere in the UP tomorrow, another day of low level clouds with high temps near 30F is expected. .LONG TERM...(Thursday night through Wednesday) Issued at 334 PM EST WED JAN 29 2020 Relatively benign weather for this time of year in the extended as models suggest ridging to traverse across the CONUS through the weekend before troughing moves in to start the work week. This will lead to above normal temperatures through the weekend, with temperatures falling back to near normal next Tuesday. Thursday night into this weekend, a weak mid-level low will slowly traverse across Upper Michigan through the weekend bringing slight chances of a wintry mix of snow showers and freezing drizzle through Saturday. This will start off ahead of this upper-level wave with lake enhancement along the Lake Michigan shoreline Thursday night. As this wave inches closer on Friday evening, widespread slight chances will return across the UP. The best chances will be across the east where 850 temps near -7C will bring some light Lake Michigan enhancement again. Uncertainties remain heading into Sunday, but it looks like there will be a break from the action Saturday night into Sunday as a low pressure is progged to pass to the north of Lake Superior Sunday, as a trough is drug across the cwa in the afternoon. Synoptic lift looks to remain just north of Lake Superior, but slight chances of a wintry mix were included along the northern fringes of the cwa. Behind the trough on Sunday, a fropa with CAA moves in. Some model differences remain, mostly with the EC(when compared to 12Z GFS/GEM). Regardless...LES chances in the W to NW wind snow belts will return Monday evening into Wednesday with no real indicators of anything significant at this time. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 625 PM EST WED JAN 29 2020 MVFR ceilings are expected to continue at all three terminals throughout this TAF period. There could be some breaks in the low-level stratus deck tomorrow, but not currently appearing to be enough to go VFR. Light and variable winds overnight will become predominantly southerly tomorrow, remaining on the light side. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 318 PM EST WED JAN 29 2020 Light winds, generally 20 kts or less, are expected across the lake this week into the early part of the weekend. Low pressure moving through northern Ontario Sunday with quick pressure recoveries immediately following will help produce strong enough pressure gradients for some W-NW gale force gusts to be possible at the surface Sunday night. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JP LONG TERM...JAW AVIATION...lg MARINE...JP
Area Forecast Discussion
National Weather Service San Francisco Bay Area
948 AM PST Tue Jan 21 2020 .SYNOPSIS...Rain is forecast to spread from north to south across our area today as a weak weather system moves into northern California. Rainfall amounts will be light to locally moderate, with no significant weather impacts expected. Mostly dry and warmer conditions are then expected for the remainder of the work week, with rain likely to return over the upcoming weekend. && of 8:33 AM PST Tuesday...Radar reflectivity indicates some light rain this morning impacting parts of the North Bay, the San Francisco Peninsula, and the East Bay. Stations in the North Bay have registered anywhere from a few hundredths of an inch up to several tenths through 8 am PST. Periods of light and perhaps briefly moderate rain will continue off/on through the day, spreading from north to south as the day progresses. Main impacts will be the wet roadways during the commuting hours. Total rain amounts will be generally between 0.25 and 0.50 inches on average with higher amounts in the North Bay Mountains and Santa Cruz Mountains and lower amounts for locations south of Santa Cruz as well as in the rain-shadowed Santa Clara Valley. No major changes have been made to the short-term grids. For additional forecast details, please refer to the previous forecast discussion. .PREV DISCUSSION...As of 3:00 AM PST Tuesday...Primary short-term forecast concerns are potential impacts from the incoming weather system. Given that precipitation will be mostly light and winds won`t be a significant factor, the primary impacts will be wet roadways during the morning and afternoon/evening commutes. Current radar shows light rain just now beginning to move onshore in Sonoma County. This initial rainfall is associated with warm advection out ahead of the primary front that is still a ways offshore. Based on the latest HRRR and NAM, light rain will remain confined to the North Bay through the morning commute, and roads should remain dry from San Francisco southward through at least mid morning. The primary frontal rain band is expected to arrive in the North Bay by mid morning, causing rain rates to increase somewhat. Rain will then spread south through most of the rest of the SF Bay Area during the late morning and afternoon hours as the front sags south. Light rain will finally reach the Monterey Bay Area by early evening. Areas that will most likely experience wet roadways during the afternoon/evening commute are the central and southern SF Bay Area as well as locations near Monterey Bay. The NAM indicates that a couple of weak waves will develop offshore along the frontal boundary by late afternoon and early evening. This will result in the frontal boundary stalling across the South Bay and Monterey Bay Area from late afternoon through much of the overnight hours, and perhaps even until a few hours after sunrise Wednesday. However, the front is forecast to gradually dissipate overnight and so rain will mostly end by daybreak Wednesday. Rain totals through tonight are forecast to be a half inch or less in most areas. The North Bay Mountains and Santa Cruz Mountains could see locally up to an inch of rain. Dry conditions are forecast from Wednesday through Friday as upper level ridging over California deflects incoming Pacific systems to our north. The second half of the work week will also feature warming temperatures as H5 heights increase to 576 dm. High temperatures are forecast to be mostly in the 60s by Thursday and Friday. However, if persistent low clouds and fog develop around the Delta and locally into the North and East Bay Valleys, similar to what occurred over this past weekend, temperatures in those areas would remain in the 50s. The consensus of longer range deterministic models, as well as model ensemble means, is for the next system to bring rain to the northern portion of our forecast area on Saturday and then south through the rest of our area by Sunday. This weekend system looks slightly stronger and wetter than today`s system, but will not likely to have significant impacts. Dry weather is then expected to return by early next week. && of 9:48 AM PST Tuesday...For 18z TAFs. A weak frontal boundary slipping through the area today will bring a mix of low cigs and/or vsby to area terminals during passage, along with some light rain. Current satellite imagery is showing widespread overcast conditions throughout the Bay Area and increasing clouds for the Monterey terminals. STS is already reporting 2sm with cigs down to 600 feet. Winds ahead of the front will likely have some light to moderate wind shear, as the surface winds will generally be out of the south while winds up about 2000 feet will be from the southwest and gusting into the mid 30 knot range. Therefore, wind shear remains in the tafs for STS, OAK, and SFO. As this frontal boundary slips out of the area, high pressure will be building quickly in its wake. This could trap some of the low level moisture that the front is leaving behind which could yield some low vsby issues at many of the Bay Area terminals overnight. The main culprit will be STS. Otherwise clouds will be clearing. This really boils down to a timing issue as to when the ridge takes hold behind the front. Most tafs do show some kind of reduction in vsby and it may need to be drop even further in later issuance`s. Vicinity of KSFO...MVFR is expected to remain through the day with a possible brief drop to IFR as the front passes between about 02Z-06Z. Confidence is low with any drop to IFR (no matter how brief) and is not reflected in the taf at this time. This will need to be monitored to see if the front comes in any stronger to SFO than forecast. At this time, it is expected to break up to a degree over the coastal range. Regardless, look for some small drops in vsby and cigs during the core of frontal passage. Winds will come around from the south to a more north to northeasterly direction behind the front and are forecast to be light. This may cause some radiational fog to develop. As it stands right now, but post sunrise on Wednesday conditions look to be improving significantly. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...VFR-MVFR. Light SE winds this morning. Showers to arrive in the early evening with MVFR cigs. Only a slight drop in vsby is expected as showers limp through the area. Otherwise, look for VFR to prevail again by this time on Wednesday. && of 09:31 AM PST Tuesday...Expect moderate to locally breezy southerly winds through this morning as a cold front approaches and moves through the waters during the remainder of the day. A longer period northwest swell will build today before peaking midweek generating hazardous seas conditions for smaller vessels. Another long period northwest swell will then arrive later this week. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tday...SCA...Pigeon Pt to Pt Pinos 0-10 nm from 3 PM SCA...Pt Arena to Pt Reyes 0-10 nm SCA...Pt Reyes to Pigeon Pt 0-10 nm SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm && $$ PUBLIC FORECAST: Rowe/Dykema AVIATION: BFG/Rowe MARINE: RGass Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Pueblo CO
800 PM MST Wed Jan 29 2020 .UPDATE... Issued at 740 PM MST Wed Jan 29 2020 No real big changes made this evening, only made minor updates to pop and snow to account for latest trends over northern Teller and far northwest El Paso counties, and added patchy fog near the CO/KS border. As an upper level trough dives southeast across the region, continue to see snow development mainly along the higher elevations. However, have also noted a slightly more focused area of light to moderate snow across north central CO which is making its way into northern Teller and far northwest El Paso counties. RAP analysis continues to show some enhanced boundary layer convergence in this location that is likely aiding in this development. Do think this focus/development may persist for a few more hours, before diminishing during the overnight hours. Until then, expect the light to moderate snow to possibly produce an additional 1-2 inches of snowfall. Highest potential for this snow will be northern Teller county, along/north of a Florissant to Woodland Park line. Some potential for a small window of light snow for locations along and north of Manitou Springs to Calhan line in northern El Paso late this evening. Confidence is lower though at this time. One other item that we are keeping an eye on is the dense fog which has been in place over southwest KS this past afternoon into the evening. There has been some northwest movement to this fog and latest time of arrival would put it into SE CO in a few hours. Veering boundary layer flow and higher dewpoint depressions should keep the bulk of this fog just to the east, but it remains possible for locations across the far eastern plains near the Kansas border to observe this fog. Have only added patchy fog wording to the forecast at this time, but may be to adjust this if it moves closer, as one quarter mile or less vis with some light icing could be possible. && .SHORT TERM...(This evening through Thursday) Issued at 237 PM MST Wed Jan 29 2020 Current, Tonight, Thursday Morning: The upper level low pressure center is located over southern Arizona and over the northern portions of the Mexican province of Sonora. The track seems to be traveling a little bit further south than the previous tracks. The main dynamics from the closed low is too far south to really impact Colorado, but the trough that created the cut- off low will pass over Colorado, causing snowfall over the mountains and over the San Luis Valley. Snowfall amounts and rates won`t cause the need for a Winter Weather Advisory. Costilla and Alamosa Counties are areas that that high resolutions models and ensembles are picking up on a short period of heavier snowfall rates as the trough axis passes over this evening. Costilla County could see up to 3 inches of snowfall from 2000 MST through the early morning hours. There is the possibility that the band of snow forms over the city of Alamosa, but at this time, it seems that the band will form to the southeast of the city. Behind the trough axis will be drier and colder air, which will shoot down the low temperatures over the mountains valleys, hence the forecast in the single digits. There is a large divide between MOS guidance over the eastern plains for low temperature forecasts, but the MET seems to be handling the boundary layer a little bit better than the MAV, so the forecast is a blend of the MET and ECS. Expect low temperatures in the teens north over the I-25 corridor, north of Highway 50, and the upper Arkansas River Valley and the 20s over the southeastern plains. Thursday: Generally dry conditions will be experienced everywhere tomorrow, the upper level pattern shifts to a northwesterly flow, which will eventually bring some isolated to scattered snow over the central mountains. High temperatures are expected to be in the 40s, again, over the plains, the 30s over the San Luis Valley and upper Arkansas River Valley, and the teens over the mountains. .LONG TERM...(Thursday night through Wednesday) Issued at 237 PM MST Wed Jan 29 2020 Overall good agreement between the models through the extended period. There are some differences in timing and storm track for storm system early next week, but the overall trend appears favorable for widespread precipitation across much of southern Colorado. Thursday night...a quick moving upper shortwave is forecast to track southeast across Colorado Thursday night. Expect snow to be ongoing over the Central Mountains, spreading south and east over the Palmer Divide and into the Eastern Mountains and I-25 corridor through the evening. As we move through the overnight hours, precipitation will shift southward into the Raton Mesa, clearing to our south by Friday morning. Snow will be the primary precipitation type, with a few sprinkles initially, changing to all snow as cold air filters into the region. Accumulations will be minor, with 1 to 3 inches over the Mountains, and a dusting along and near I-25. Friday into Sunday...high pressure is forecast to move across the region through the weekend ahead of the next upper storm system. Temperatures will be cool on Friday as north winds keep highs in check, with generally 50s across the region. Heading into the weekend, flow aloft transitions more westerly for Saturday which will help highs make it into the mid 60s. The next upper storm system will move into the western states on Sunday forcing flow aloft southwesterly. Sunday will be the warmest day, with lower 70s across the region. Expect dry conditions through this time period with mostly clear skies. Sunday night into Wednesday...the next upper level storm system is forecast to move across the area early next week, with the potential for widespread snow across the region. Snow will likely move into the Continental Divide Sunday night, with orographics favoring the San Juan Range. As the upper storm moves over the region on Monday, a strong cold front is forecast to drop south across the Plains. Models at this time are depicting about an 18 hour window of deep upslope flow over the Plains late Monday afternoon, into Tuesday morning. This would help enhance snowfall potential for the Plains, especially the Palmer Divide, Eastern Mountains and Raton Mesa. Several inches of snowfall are possible. Much colder air will move across the Plains with the cold front, with 700 mb temperatures falling to near -15C. These temperatures, combined with the upslope flow could enhance the snowfall over the region. There are some model differences between the GFS and ECMWF in regards to how far north or south the storm tracks, and storm speed. Slight variations in either could lead to when and where heavier precipitation will fall. Currently, models have dry conditions by Wednesday as the upper system departs the region, but this could change. Mozley && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 237 PM MST Wed Jan 29 2020 KALS: Banded snowfall is expected in the vicinity of KALS during the evening and into the overnight. The heaviest snow is expected to be over Costilla County, but it is possible for the banded snow to form over KALS. If that band does form, lower flight categories are likely, but at this point in time VFR conditions are expected throughout the forecast period. Clearing skies are expected tomorrow morning. KCOS and KPUB: Lower clouds will be over KCOS and KPUB, but VFR conditions are expected throughout the forecast period. Clearing skies are expected tomorrow morning. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...RODRIGUEZ SHORT TERM...SKELLY LONG TERM...MOZLEY AVIATION...SKELLY