Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/06/17

Area Forecast Discussion
National Weather Service Billings MT
711 PM MST Sun Feb 5 2017 .UPDATE... Main reason for update this evening is the Canadian cold front which is pushing into our cwa ahead of schedule. Already seeing a wind shift to N-NE winds at Judith Gap and Roundup, where temps have fallen quickly to the teens. Latest HRRR is catching on to this and suggests a wind shift to Billings before 06z. Have updated wind grids to show this earlier shift, and have also adjusted low temperatures down several degrees due to the cold advection behind the fropa. We may also see some stratus or perhaps even fog advect from the north during the overnight hours. Will make no changes to wind advisories in effect for Livingston and Nye, where gusts continue to exceed 50 mph. Will be interesting to see how far west/south the Canadian front makes it into tomorrow morning. Given our abundant snow cover and current trends, am confident it will make it closer to the foothills than models are suggesting, making for a difficult temperature forecast tomorrow. Billings will likely stay on the cold side of the surface boundary on Monday. JKL && .SHORT TERM...valid for Mon and Tue... Active period of weather for the short term. Early on, winds will be an issue for the western valleys, later in the short term (Monday night mainly), the potential for heavy snow showers draws all the attention. Winds have been gusting 50-55 mph at Livingston this afternoon with gusts to 60 mph at Nye. Models were pointing to the strongest winds being this evening, with winds gradually backing off overnight into Monday morning. Reason for this is probably the models were pointing to instability increasing from mountain top level overnight. Models are notorious for not handling the cold air in the western valleys, which will aid in the low level stability and producing a stronger stable layer at mountain top level than what the models think. Will keep the advisory going and hit the wording hardest for tonight. Attention then turns to the approaching trough for snow potential Monday night into early Tuesday. The passing of the trough looks a little farther north and not quite as sharp as previous runs. The ECMWF was a little stronger with the shortwave, but the farther north passage would mean less upslope potential and more downslope at 700mb. Upslope does develop, but it was shallow and very quick as it was mainly for a 6 hour period mid to late evening. Instability was there with lapse rates 850-500mb at 7.5c/km. Frontogenesis was impressively strong and should provide strong ascent. The EC hits the west hard during the evening and then weakens ascent overnight as frontogenesis sinks south. The GFS hits areas south of Billings hardest and drifts ascent south out of the area quickly overnight. The EC does hang frontogenesis up along the slopes overnight Monday which could lead to a longer period of snow showers there. All this being said, the system moves through very quickly and looks like a snow shower event and not so much of a large and broad scale synoptic event. Will opt to not issue any highlights at this time due to model differences, speed of system and overall northward shift of the trough providing downslope flow through mid levels. Have lowered snow amounts slightly as models have come in generally lighter on precipitation amounts with the speed of the system. Will generally go with 1-3 inches, with the potential for 2-4 inches over the west and south. Future shifts may be able to pin point the most likely location for 3-4 inch snow totals or where the models hang up lift for a prolonged period of time. Will keep messaging potential heavy snow showers Monday night. Will linger snow showers potential during the morning and have raised PoPs for Tuesday morning. Temperatures Monday will be tricky as the GFS lifts the arctic off the slopes and warms western and central zones into the 30s. The EC keeps the arctic in place as it drops in tonight and keeps highs in the lower 20s. Will lean toward the EC as believe the arctic will stay in play. Also guidance has not been good at all in handling temperatures during this latest pattern. Tuesday looks chilly as well with the arctic firmly in place. TWH .LONG TERM...valid for Wed...Thu...Fri...Sat...Sun... Latest models for Wednesday have much less energy working across the area, thus PoPs have been lowered accordingly. Through the remainder of the forecast period, it will be a general drying trend. However, there will is still energy moving through the zonal flow, so still have some chance PoPs. With the zonal flow, winds will be downsloping so still expect temperatures to warm through the period. Winds continue to look gusty along the foothills later in the week as some gap flows could increase. Reimer && .AVIATION... High confidence that MVFR or possible IFR ceilings will move into KBIL and KMLS late tonight through early Monday morning. Patchy fog is also possible in these areas, but confidence is not as high. Otherwise, VFR will prevail tonight. Snow will move into areas mainly W of KBIL during Monday with MVFR/IFR conditions. VFR to MVFR will prevail elsewhere. Areas of mountain obscuration over the Beartooths, Absarokas and Crazys will become widespread on Monday. Gusty SW surface winds to 50 kt over KLVM will become lighter from the E sometime Mon. morning. A cold front with a band of snow will affect the area Mon. evening. Arthur && .PRELIMINARY POINT TEMP/POPS... Mon Tue Wed Thu Fri Sat Sun ----------------------------------------------------------- BIL 011/028 012/018 001/019 016/044 037/048 026/037 021/038 02/J 84/J 33/S 21/E 22/R 11/B 11/N LVM 036/041 017/028 013/034 026/051 042/050 028/039 020/038 16/W 93/J 34/S 32/R 33/R 22/O 21/N HDN 014/026 009/018 907/017 009/044 033/046 024/037 015/036 01/E 74/J 33/S 21/E 12/R 11/B 11/B MLS 011/019 004/011 912/010 004/039 033/045 025/034 017/034 01/E 73/J 22/S 21/B 12/O 11/B 11/B 4BQ 019/029 008/019 905/018 009/043 034/047 024/037 017/034 00/E 73/J 22/S 21/B 11/B 10/B 11/B BHK 012/017 004/010 913/007 001/038 031/045 023/032 016/032 01/E 73/J 22/S 21/B 11/E 11/N 11/N SHR 024/035 013/021 005/022 014/046 033/048 024/037 016/036 01/B 74/J 33/S 21/B 11/B 11/B 21/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Wind Advisory in effect until 1 PM MST Monday FOR ZONES 65-66. WY...None. && $$
Area Forecast Discussion
National Weather Service Hastings NE
550 PM CST Sun Feb 5 2017 .SHORT TERM...(This evening through Monday) Issued at 326 PM CST Sun Feb 5 2017 A few mid and high level clouds have been moving through the forecast area this afternoon. The surface high over the area overnight has been moving to the east but is a little slower and winds have not turned to the south as much as was expected. Temperatures have been slow to warm up without the mixing. The surface high is expected to continue to move to the east and winds should continue to come around to the south. That will bring in additional moisture. There has been some persistent stratus across southern Kansas and Oklahoma this afternoon and with the south winds tonight, the stratus is supposed to redevelop and move toward the north. The expectation is that the stratus will move into the southeastern part of the forecast area and there will be a little fog around the edges of the stratus. The SREF probs and HRRR have some fog in the southeast but do not get it too far into the forecast area. Have kept the patchy fog for much of the area and tried to keep areas further to the southeast. The fog is expected to linger into the morning hours and just get out of the area by mid day. Skies will be partly to mostly cloudy during the day. Temperatures will be a little warmer. .LONG TERM...(Monday night through Sunday) Issued at 326 PM CST Sun Feb 5 2017 A cold front moves through the forecast area Monday evening, but the cold air does not move into the area until during the day on Tuesday. Even then, the southern part of the area should warm up pretty well since the cold air will not reach that area until late Tuesday afternoon. Winds will be from the northwest and increase some in the afternoon as the colder air moves into the area. An upper level wave moves into the area Tuesday night and brings a chance for precipitation to the area. Temperatures are cold enough hat it will all be snow. The better chances for snow will be in the northern part of the forecast area, mainly along and north of Interstate 80, late Tuesday night into Wednesday morning. By Wednesday afternoon and into Thursday, the PoPs are lower and more sporadic, but mostly in the north. There will be some accumulation, but at this point it does not look to be heavy. The problem is that each run of the models has just a slightly different location. From Thursday through Friday evening expect dry conditions and temperatures will be warming back up again. It is short lived, because another cold front moves through Friday night and brings colder temperatures again on Saturday. There is also an upper level wave that brings a chance for precipitation. This time the temperatures start off warm enough to be mostly rain then mix with or change to snow before coming to an end Saturday night. Dry and cooler again for Sunday. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday evening) Issued at 538 PM CST Sun Feb 5 2017 Low level stratus across Oklahoma this evening is expected to creep northward overnight...eventually spreading into north central Kansas and extreme south central Nebraska early Monday morning. While the low level stratus and significantly reduced visibilities are expected to remain to the south of the terminals...cannot rule out a few hours of MVFR VSBYS at either terminal around dawn...with VFR conditions returning during the morning hours. Overall...light southerly winds are expected through the period with CIGS expected to remain at or above 12KFT. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...JCB LONG TERM...JCB AVIATION...Rossi
Area Forecast Discussion
National Weather Service Lincoln IL
914 PM CST Sun Feb 5 2017 .UPDATE... Issued at 913 PM CST Sun Feb 5 2017 The rest of the night should be uneventful weather-wise, with mid and high clouds drifting across Illinois in the westerly flow aloft. Low temps have been dropping very close to forecast lows already in some areas, so minor adjustments to low temps downward were made. The next concern will be the advance of fog and low clouds into our forecast area from the south, as a warm front progresses north into Illinois. While the depth of moisture will be very shallow, it appears there will be enough lift for some drizzle to develop south of I-72 after 9 am tomorrow. Forecast soundings indicate that sufficient lift and moisture deep enough for rain showers might be delayed until afternoon. Will be adding drizzle to the morning forecast, and adjust timing of onset of rain showers. Thunder chances look to remain mainly Monday night, and will keep thunder out of the Monday forecast. Updated forecast info will be available shortly. && .SHORT TERM...(This evening through Monday) ISSUED AT 255 PM CST Sun Feb 5 2017 Mid/high clouds currently evident on visible satellite imagery across Iowa/Missouri will stream eastward into central Illinois late this afternoon and evening...resulting in a period of partly to mostly cloudy skies. Based on satellite timing tools and HRRR RH appears these clouds will tend to dissipate and push into the Ohio River Valley overnight. Thanks to light winds and the overall partly cloudy conditions, low temperatures will bottom out in the upper 20s and lower 30s. Clouds will once again begin to increase Monday morning as a developing storm system approaches from the southwest. Current satellite shows low clouds poised upstream across Oklahoma/Arkansas and these will spread northward as the system takes shape. HRRR has a good handle on the clouds right now and shows them reaching the southeast KILX CWA south of I-70 between 10z and 12z...then overspreading the entire area by late morning. While forecast soundings show ample low-level moistening indicative of low clouds and patchy fog, mid/upper levels remain dry throughout the day. As a result, am not expecting much precip to develop and have therefore kept Monday afternoon PoPs in the slight to low chance category. With increasing southerly winds, high temperatures will climb into the lower to middle 50s. .LONG TERM...(Monday night through Sunday) ISSUED AT 255 PM CST Sun Feb 5 2017 The weather system coming into the area Monday night will be deepening as it moves in, which will lead to much higher pops than during the day Monday. The cold front associated with this weather system will start out well west of the area, but should quickly move east during the night, reaching western IL by morning. Most models agree on this timing, but the ECMWF is slightly slower with the front. By noon on Tuesday, the front will be through most of the area. Showers will increase and spread over the area Monday night and then continue to the east and northeast during the morning hours of Tuesday. Models continue to forecast sufficient instability over the whole area Monday night and then over the eastern part of the CWA Tuesday. So, chance to likely thunderstorms will remain included in the forecast through Tuesday morning. With the system exiting the area quickly on Tuesday, thunderstorm chances will drop by Tuesday afternoon into the slight chance category, with the chance of showers remaining the the eastern parts of the CWA. This system will move northeast into the Great Lakes region very quickly, so Tuesday night will now be dry and temps will begin to fall as the colder air advects into the region. Models then show a couple of weak impulses moving across the CWA on Wed. One impulse moves across the southern part of the CWA, while another one moves across the northern part of the CWA. Both impulses move through Wed afternoon. However, not very confident in these features given they both are producing precip underneath a large area of cold high pressure. Will keep the pops at slight chance for the northern one, but will maintain the chance pops for the impulse moving across our south. Since models also struggle with the timing of these small features, will have the southern impulse chances during the whole day. Once these weak impulses move through the area, high pressure will dominate the weather over the CWA with dry weather through Friday night. The next weather system to effect the area will arrive Sat. Based on the model output, this system doesn`t begin to get active until it reaches central IL. Precip will develop and increase over the CWA with precip chances extending from Sat through Sunday. The precip over most of the area will be in the form of rain. A mix of precip and just snow will be possible early Sat morning and then again late Sat night into Sunday morning. This mixed precip will remain over the northern part of the CWA, roughly along and north of a Rushville to Bloomington line. Temps will remain quite warm Tue, but then drop once the front goes through and be below normal for Wed and Thur. The rest of the week and into next weekend will warm back up as the high pressure shifts off to the east and southerly winds return to the area. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 550 PM CST Sun Feb 5 2017 A weak disturbance will pass across central Illinois this evening, bringing mid-level clouds at 12K FT for several hours of the overnight. RAP and NAM forecast soundings indicate the ceilings will lower to around 12000ft during the 03z-06z time frame, the improve toward sunrise as the band of clouds departs to the east. Main aviation forecast concern continues to be the approach of a stronger storm system and its subsequent lower clouds and precip on Monday afternoon. The latest HRRR indicates IFR ceilings spreading northward from Missouri/southern Illinois late tonight, remaining south of the KILX terminals until after sunrise. Based on HRRR forecast and NAM soundings, have introduced IFR ceilings at KSPI by 15z...then further north to KBMI, KCMI and KPIA by 17z-19z. Ceilings are expected to lower to LIFR after 20z from south to north, with visibility dropping to IFR during the same time frame. Winds will initially be from the NW at around 5-6kt early this evening, then will become light/variable by midnight. A southerly wind of around 10kt will develop by 15z- 16z Monday morning and continue through the afternoon. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Shimon SHORT TERM...Barnes LONG TERM...Auten AVIATION...Shimon
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
908 PM CST Sun Feb 5 2017 .UPDATE... Updated for evening discussion. && .DISCUSSION...Local radars had a band of showers and a few thunderstorms moving east along the Highway 82 corridor. Latest surface analysis had a warm front between Highway 84 and Interstate 20. This front will drift a little farther north tonight and shift the band of convection a little farther north. Have added mention of thunder in the north tonight with the update. Across the south patchy dense fog development is possible toward morning. /22/ Prior discussion below: Tonight and Monday...Satellite and surface data are indicating the surface warm front has pushed to just south of the Interstate 20 corridor at 21Z. North of the boundary, cloudy, cool and showery weather has been the rule through the day as isentropic ascent continues overtop the cool airmass. To the south of the boundary, clouds have decreased and temps have increased with readings as warm as the mid 70s in the far south. The warm front should continue to slowly lift northward overnight and into Monday morning. The dense cloud cover and showery conditions will continue to the north of the boundary overnight, while areas to the south will see decreasing clouds during the evening. Boundary layer cooling will lead to fog formation after midnight over the south with some areas becoming dense, especially over the far south where expected lows in the mid 50s surpass current crossover temps in the upper 50s to near 60. The HRRR is also showing dense fog formation possibilities, but presently looks to remain patchy. The fog will lift by mid morning with the majority of the remaining showers lifting north of the area by noon. Monday will be quite warm over the region with near record maximums in the mid and upper 70s, and possibly approaching 80 over some of the southern portions. With such heat this time of year would be concerned about convective potential, but building cap above the boundary layer will put a lid on that possibility./26/ Monday Night through Sunday...Our focus for Monday night and onward continues to be on a passing shortwave and its potential to initiate possibly severe thunderstorms Tuesday into Tuesday night. Model guidance has trended toward an overall less amplified upper air pattern over the last few cycles, with decent agreement from the NAM as it has begun to cover the Tuesday period. A lead shortwave trough is expected to be sliding from TX/OK into Arkansas on Monday night, with a second shortwave displaced northwestward over the Northern High Plains. This slightly slightly out-of-phase setup will result in only weak cyclogenesis of a surface low moving from the Plains to the Midwest Monday night into Tuesday. A cold front extending south from this low should slowly advance toward a Shreveport-Memphis line by Tuesday night. Southerly flow in advance of the cold front will bring a warm and moist airmass northward along the Mississippi River, with dewpoints reaching the low 60s in our northeast LA parishes and southeast AR counties by early Tuesday morning. As mid-level heights fall ahead of the approaching shortwave, the combination of moistening low levels and cooling mid levels could result in a weakly capped (10-20 J/kg of MLCIN) but unstable atmosphere with 1000 J/kg MLCAPE or greater around the Delta region Tuesday morning. A stronger cap to the south will limit the potential for thunderstorm development closer to I-20 and areas south of there. Especially with any lift from the passing shortwave, there is a potential for severe thunderstorms to develop in the vicinity of the frontal boundary. Expected 40 to 60 kts of 0-6 km shear is sufficient to organize these thunderstorm updrafts into supercells. Low-level shear values near 30 kts and effective SRH around 200-300 m2/s2 will be supportive of a tornado threat especially while morning LCL heights are in the 500m range. The threat for severe weather becomes a little more uncertain heading into Tuesday afternoon and Tuesday night as the shortwave moves east of the front. Even with weak mid-level height rises behind the shortwave additional storms will be possible later into the day if strong enough daytime heating or the added focus of outflow boundaries can help updrafts overcome the cap. Damaging wind gusts and large hail would be the primary threat from storms by Tuesday afternoon. Will keep a Limited threat area for severe thunderstorms with possible tornadoes going across the northern one-fourth of the forecast area on Tuesday where severe chances are greatest. Low end shower and thunderstorm chances continue into Wednesday before the cold front finally clears the area Wednesday night. A brief cool down for Thursday will be followed by a return to warm weather as a broad ridge builds over the country. Rain chances return the forecast over the weekend ahead of another deep shortwave sliding across the U.S. /NF/ && .AVIATION... 00Z TAF discussion: IFR/LIFR Cigs with -RA wl cont this evng north of I-20 while VFR conds cont south of I-20. The -RA wl taper off by 06Z but IFR/LIFR conds wl cont tonight in the north. IFR/LIFR cigs and vsbys wl develop across the southern half of the area by 09Z. Conds wl slowly improve areawide after 15Z to VFR by 18Z. VFR conds wl prevail arewide Monday aftn through evng. /22/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 55 78 60 76 / 23 9 9 47 Meridian 51 78 59 75 / 52 10 9 45 Vicksburg 54 76 61 78 / 20 14 20 39 Hattiesburg 54 76 59 76 / 10 5 7 38 Natchez 59 76 62 77 / 13 13 16 33 Greenville 51 72 60 75 / 82 32 41 48 Greenwood 52 74 60 74 / 90 27 34 60 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ NF/22/26
Area Forecast Discussion
National Weather Service Memphis TN
829 PM CST Sun Feb 5 2017 .DISCUSSION...02Z Surface analysis places a warm front over portions of Southern Mississippi, Northern Louisiana, and into the Red River Valley of Texas and Oklahoma. Regional WSR-88D radar trends have shown an increase in showers near the warm front. Latest 00Z WRF and HRRR suggest best potential for showers and perhaps an isolated elevated thunderstorm will be predominantly overnight across the remainder of the Mid-South. Updated rain chances to reflect these trends. Otherwise, the forecast overall is in good shape. CJC && .PREV DISCUSSION... /issued 525 PM CST Sun Feb 5 2017/ UPDATE... Updated to include the 00z aviation discussion. PREV DISCUSSION... /issued 307 PM CST Sun Feb 5 2017/ DISCUSSION... The back edge of clouds continues to sit generally from a Forrest City, Arkansas to Savannah, Tennessee line. Expect the clouds to slowly begin to lift north over the next couple of hours as a secondary warm front that remains over Southern Mississippi begins to lift north. Clouds should cover the entire Mid-South by midnight. Showers with a few embedded thunderstorms associated with the front will spread into North Mississippi this evening and increase in coverage during the overnight hours. Low temperatures will likely occur this evening before holding steady over even slightly rising. The warm front will surge through the entire Mid-South by Monday morning. Expect lingering showers and thunderstorms over portions of Northwest Tennessee. Clouds should scatter out some over North Mississippi, possibly into areas of West Tennessee. This should allow temperatures to warm up into the lower 70s. Isolated shower and thunderstorm development may occur over Eastern Arkansas during the afternoon as the upper trof begins to swing east. The upper trof will move into the area Monday Night. Showers and thunderstorms will blossom over the Mid-South Monday Night ahead of the upper trof. Some of these storms could become severe. Best timing for severe weather will come Monday Evening into Tuesday Morning across the Mid-South. Expect by mid-day Tuesday the severe threat will diminish as the upper trof pushes east. Clouds may actually begin to clear behind the morning activity and would not be surprised to see temperatures surge into the mid 70s across areas along and west of the Mississippi River during the afternoon hours. The trailing cold front will move into the area Tuesday Night. However, it doesn`t look like the front will quickly pass through the CWA like models have been showing. The 12Z runs of the NAM, GFS, and ECMWF have the front stalling out over the Mid-South into Wednesday before clearing the area Wednesday Night. As a result, have added chances for rain to the forecast for Wednesday and Wednesday Night. Cooler temperatures will filter into the area behind the front. Both the GFS and ECMWF now have the next upper trof moving in before the cold air gets in place. Thus, the chances of snow have diminished. Temperatures will quickly rebound by Friday as surface high pressure shifts east. Chances for showers will begin to occur on Saturday ahead of the next cold front. The front is expected to move into the area Saturday Night into Sunday. Thus next weekend could be a wet one. && .AVIATION... /00z TAFs/ Low clouds are streaming back to the north rapidly this evening and will overspread the remainder of the area over the next few hours. IFR conditions are observed at KTUP and will persist through much of the period. Farther north, initially MVFR ceilings will eventually lower to IFR with scattered showers and patchy drizzle expected later tonight into Monday. Ceilings are expected to improve slightly Monday afternoon, but should still remain below 2000 ft. Light south to southeast winds will prevail overnight, becoming south at 10-15 kts by midday Monday. Johnson && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
Area Forecast Discussion
National Weather Service Melbourne FL
1030 PM EST Sun Feb 5 2017 .DISCUSSION... Pressure gradient will slacken as the ridge builds overhead, resulting in light and variable winds overnight. Minimal cloud cover will couple with these winds to generate strong radiational cooling conditions that will promote fog formation. Have increased fog potential across north half of FA as both HRRR and local WRF models show reduced visibilities expanding across the area overnight. Lows in the mid to upper 50s, except lower 60s Martin coast. On Monday, low level flow veers to the E/NE as the ridge builds over the peninsula. Under partly/mostly sunny skies, max temps will be in the M/U70s except L70s along the Volusia County coast due to the cooler shelf waters. && .AVIATION... Primary concern will be fog development across the northern terminals mainly TIX-ISM northward. IFR VSBYs possible lifting by 14Z. && .MARINE... No significant changes to current coastal waters forecast. Tonight-Monday...Gentle to moderate N/NE breeze bcmg E/NE as a weak frontal trof off the SE coast lifts up the east coast, allowing high pres centered over the GOMex to drift over the SE coast. Diminishing NE swell will continue to enhance lcl wind waves...nearshore seas 4- 5FT subsiding to 3-4FT...offshore seas 5-6FT subsiding to 4-5FT. && .PRELIMINARY POINT TEMPS/POPS... DAB 53 73 60 80 / 0 0 0 10 MCO 54 79 59 81 / 0 0 0 10 MLB 55 76 62 79 / 0 0 0 10 VRB 54 77 63 80 / 0 0 0 10 LEE 52 77 59 81 / 0 0 0 10 SFB 53 78 59 81 / 0 0 0 10 ORL 54 79 60 81 / 0 0 0 10 FPR 55 78 62 79 / 0 0 0 10 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ Kelly/Sharp
Area Forecast Discussion
National Weather Service San Francisco Bay Area
349 PM PST Sun Feb 5 2017 ...A Wet and Windy Week Ahead... .SYNOPSIS...A Pacific storm system will bring the first round of rain back to our region this evening through tonight. A moist flow off the Pacific will then produce periods of rain from Monday Night through Tuesday night with rain possibly continuing in the North Bay into Wednesday. One final system will bring additional rain and wind to the entire region Thursday and Thursday night. Dry weather is expected to return by next weekend. && .DISCUSSION...As of 3:00 PM PST Sunday...Hard to believe with the occasional breaks in the clouds today plus seasonably mild temperatures that rainfall will rapidly return to the San Francisco and Monterey Bay Region starting this evening. Satellite nicely shows a fast moving cold front associated with a 995 MB low well to our northwest quickly advancing to the coast. KMUX radar is still mostly clear of echoes, although last half an hour we are starting to see the leading edge being picked up. Models are generally in good agreement and the last few runs of the HRRR have mostly stayed consistent, so looking for rain to get to the coast by early in the evening and then quickly move through northwest-to-southeast generally by midnight. Rainfall could be locally heavy at times as the band moves through although rain rates are not forecast to reach levels that would trigger many hydro concerns. As the front nears southerly winds will also increase with local gusts over 30 mph likely (over 45 mph in higher elevation spots). Looks like it will mostly stay below advisory levels, so did not issue a product. Rain will then change to showers behind the front. By Monday afternoon urban locations are looking at between 1/4" and 3/4" with higher elevation locations generally 1/2" to locally over 1". Due to an anticipated higher than normal number of cars on the road this evening compared to most Sundays, there could be a fair number of problems especially since it should coincide with the highest rain amounts. On wildcard is the remote possibility for thunder this evening mainly near the coast, although lightning strikes well to our west have been trending downward. Active weather will then continue for the remainder of Monday through at least Thursday night as multiple weak impulses combine with a moist flow overhead. IVT values that will briefly peak close to 500 tonight will have several more spikes (potentially peaking around 750 kg/m/s late Monday into Tuesday) through the week. widespread rainfall will return late on Monday and continue through most of Tuesday. Rainfall from the second system will be considerably higher -- urban locations 2/3" to 1.5" with 1.5" to locally more than 3" for coastal ranges. Current forecast from CNRFC keeps streams and rivers below flood stages, however all of them are expected to have rapid rises. Will be keeping a close eye on the latest numbers to see how they are adjusted after the first round of rain tonight. Southerly winds will again be of concern with speeds likely over 30 mph. Rain will again change to showers for most locations by Tuesday night and continue to the first half of Wednesday before generally tapering off by late in the day. On Thursday the third, and likely last major round of rain will move through with precipitation anticipated going into Friday. Current estimates show similar precipitation values for it compared to the system that will race across tonight. A ridge of high pressure will likely build back to the California coast starting over the weekend with the first half of next week looking mostly dry. && .AVIATION...As of 3:40 PM PST Sunday...Lowering cigs the rest of the afternoon as a frontal system approaches. Gusty south to southeast winds switching south to southwest sometime after 06Z which is when we expect fropa. A period of moderate rain is expected just ahead of fropa. Winds slowly decrease overnight. Vicinity of KSFO...MVFR cigs with rain becoming widespread after 02Z. Vsby may drop to 4-6 miles in heavier rains. Southeast winds gusting to 30 kt switching to southwest after 07Z. Rain turns to showers after 07Z and lasts through midmorning Monday. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Cigs lowering to MVFR after 04Z with rain spreading into the area. Fropa expected around 09Z with rain becoming showers. Gusty southeast winds to 30 kt at KSNS with SE wind just ahead of fropa. && of 3:40 PM PST Sunday...A cold front will move across the coastal waters this evening and tonight resulting in increasing southerly winds and a slight chance of thunderstorms. Gusty winds will produce small craft advisory conditions with fresh swell. Winds will turn west to northwest and decrease on monday but will increase again Tuesday as another system approaches the area. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...Mry Bay until 3 AM SCA...Pt Arena to Pt Reyes 0-10 nm until 3 AM SCA...Pt Reyes to Pigeon Pt 0-10 nm until 3 AM SCA...Pigeon Pt to Pt Pinos 0-10 nm until 3 AM SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm until 3 AM SCA...Pt Arena to Pigeon Pt 10-60 nm until 3 AM SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm until 3 AM SCA...SF Bay from 9 PM until 3 AM && $$ PUBLIC FORECAST: Bell AVIATION: W Pi MARINE: Sims Visit us at Follow us on Facebook, twitter, and youtube at: