Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/20/21

Area Forecast Discussion
National Weather Service Albuquerque NM
917 PM MDT Mon Apr 19 2021 .UPDATE... Really there is not much to update since this evening as the cold front continues to be on track moving through the NE and E plains of New Mexico. Front should be reaching KTCC and KLVS over the next hour. A sharp wind shift can be expected with a drop in temps and increase in wind speeds. Wind advisory looks on track and will keep blowing dust in the forecast as well. The front might be an hour faster than hi-res models but overall timing of the front looks good. Any changes to the forecast grids were for near term trends with the front. 39 && .PREV DISCUSSION...528 PM MDT Mon Apr 19 2021... .AVIATION... 00Z TAF CYCLE Surface analysis and even the visible satellite imagery show the cold front moving into NE New Mexico stretching from Raton to Clayton. The front should reach KTCC around 04-06Z this tonight and KLVS around 06-08Z with strong N/NE winds behind the front. The front should then reach KROW around 10-12Z. Low stratus should develop behind the front but there may be a time lag between when the front pushes through and when the low clouds develop. So look for MVFR ceilings to develop a couple hours after frontal passage. The other issue for KTCC may be blowing dust which could reduce visibility for a couple hours tonight. Latest HRRR and GLAMP seem to have a good handle on these scenarios so loosely based TAFs off this guidance. Otherwise ceilings should improve late in the morning. Rest of the TAF sites should have VFR conditions with mainly SW/W winds. Cold front could reach the central mountains later in the morning tomorrow and looking at a shift in winds from the east at KABQ but we are not looking at winds strong enough for an airport weather warning. 39 && .PREV DISCUSSION...246 PM MDT Mon Apr 19 2021... .SYNOPSIS... A strong cold front will push into eastern New Mexico tonight, bringing very strong winds to the plains. The strongest wind gusts are expected starting around midnight with gusts near 50 mph. Temperatures will cool on Tuesday behind the front with highs 20 to 25 degrees cooler across the east. A gradual warming trend is then in store through the remainder of the week although highs won`t reach within normal again until Friday. Typical springtime breezy to windy conditions are in store each afternoon. Dry conditions also prevail for most this week outside of spotty high terrain showers and thunderstorms each afternoon. && .DISCUSSION... SHORT TERM...(TONIGHT THROUGH TUESDAY NIGHT)... Strong cold front poised over southeast CO this afternoon to push into eastern NM tonight. Meager amounts of rain and snow are possible from Raton Pass to near Clayton with the front which may also cause some localized visibility reductions for a short period of time. Low clouds will eventually fill in behind the front as well. Guidance has backed off somewhat in regards to wind speeds, but will leave the current wind advisory as is. Also could be some reduced visibilities in blowing dust. The front appears as if it could reach into the Rio Grande Valley late tonight, but washes out fairly quickly. Low temperatures Tuesday morning over ne NM will be in the low to mid 20s, but on the late side of the season, so will pass on any freeze highlights for tonight. Highs Tuesday over the east will be about 15 to 25 degrees colder than normal, and near to about 10 degrees colder than normal central and west. Low level easterly flow returns Tuesday night, and the east wind into the Rio Grande Valley is forecast to be stronger. Lows Tuesday night will be slightly colder east central and southeast. LONG TERM...(WEDNESDAY THROUGH MONDAY)... By Wednesday morning, an H5 low will be centered over the Great Basin, and southwest flow ahead of it will strengthen over New Mexico in response. No appreciable moisture will be associated with this feature, and minimum humidities west of the RGV will continue to fall into the low teens and single digits. Southwest winds at the surface will also strengthen across the west with gusts of 35 to 45 mph possible. This will lead to the return of critical fire weather conditions in the area. High temperatures will warm several degrees, reaching closer to normal across the west, but still well below normal across the east. The aforementioned trough weakens as it crosses CO on Thursday which may result in a few rain and high elevation snow showers. Otherwise, under southwest flow, temperatures will continue to warm to within a few degrees of normal across the area. Another trough looks to cross the state on Friday, and while model differences still exist in its overall track, they are in fairly good agreement that it will be lacking substantial moisture. Again, a few showers and an isolated thunderstorm or two will be possible over the northern high terrain, but increased cloud cover may be more common across the north. A relatively quiet weekend is then on tap as an area of high pressure builds over the desert SW. This will allow for the continued warming trend with high temperatures well above normal on Sunday. Eyes then turn to early next week when another closed low moves into the western CONUS. Still lots of details to be ironed out with this system, but it could offer the next chance of appreciable precipitation. 15 && .FIRE WEATHER... Dry northwest flow aloft with colder than normal temperatures over eastern NM through Wednesday, thanks to a strong cold front moving though the region tonight. Some spotty elevated critical fire weather conditions possible on Tuesday west central and northwest. Stronger southwest to west winds Wednesday combined with low humidities and high instability are outlooked for much of the RGV westward, therefore have issued a Fire Weather Watch for Wednesday afternoon and early evening. One to 3 hours of critical conditions are possible Thursday afternoon mainly from the Central Highlands across the Northeast Highlands along the I-25 corridor. An upper trough Thursday and Friday will bring a modest increase in moisture and chances for showers Thursday through Friday over portions of the north and west. The upcoming weekend appears dry as a ridge aloft dominates and temperatures rebound to above normal. Critical fire weather conditions are possible, on Sunday over eastern NM. && .ABQ WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Wednesday afternoon through Wednesday evening for the following zones... NMZ101-105-106-109. Wind Advisory until 6 AM MDT Tuesday for the following zones... NMZ230>232-234>236. && $$
Area Forecast Discussion
National Weather Service Gaylord MI
900 PM EDT Mon Apr 19 2021 .UPDATE... Issued at 900 PM EDT Mon Apr 19 2021 Cold air continues to sweep into the Western Great Lakes region late this evening in the wake of a cold front that moved thru Michigan today. Closed upper level low is now swinging thru Eastern Upper Michigan...providing synoptic support as well as some mid level moisture to produce an area of light rain and snow currently impacting much of our CWA. A look at upstream radar KMQT shows a multi-banded structure to ongoing lake effect precip across Upper Michigan...with a few surface obs briefly reporting some heavier snowfall within some of these bands. Latest RAP suggest the upper low and associated trough axis will not clear our CWA until after 06Z...after which time W/NW flow lake enhanced snow bands should set up across our CWA during the overnight hours. Have significantly increased POPs thru the night and into Tuesday across much of Northern Lower Michigan. Initial rain/snow mix this evening will certainly limit the potential for snow accumulation across all but the higher terrain of Northern Lower Michigan...but eventually precip should switch to all snow overnight. Overall...expect an inch or two of new snow across northern portions of Chippewa county and less than an inch for the rest of Eastern Upper Michigan thru tonight. Expect less than an inch across our snowbelt areas of Northern Lower Michigan...but will need to keep an eye on this for the potential of some locally higher amounts. Will definitely keep all Freezing Warning headlines in tact with overnight lows expected to drop into the upper 20s along our Lake Michigan shoreline. && .NEAR TERM...(Through Tonight) Issued at 252 PM EDT Mon Apr 19 2021 ...Much colder air arrives... High impact weather potential: Another freeze expected across our vulnerable fruit growing areas of northwest lower Michigan tonight. Lingering gales. Pattern synopsis and forecast: Sharp shortwave trough rotating across the northern Great Lakes early this afternoon, with its attendant surface low pressure pivoting east across northern Ontario. Cold front extends south from this low, making steady east progress across Lake Huron. Gusty west winds ushering in a shot of much colder air behind this front, with falling temperature into the 30s across the western Great Lakes (with wind chill values several degrees colder yet). While most widespread and organized showers have now exited off to our east, burgeoning lake processes and "wrap around" moisture are resulting in increasing snow shower activity across the snow belts of central and western upper Michigan. Winter-like airmass will continue to spill into the area tonight...bringing more hard freeze concerns and light lake effect snow showers as it does so. Primary forecast concerns/challenges: Main emphasis is on temperature trends, attendant freeze concerns, and light lake effect snow potential tonight. Details: Expect lake effect snow showers to increase in coverage and intensity into the snow belts of eastern upper Michigan later this afternoon and evening as H8 temperatures fall into the negative teens across Lake Superior and synoptic moisture contribution increases. Limited inversion heights (just a bit over 5kft) and a relatively short window for most organized snow showers (best parameters exit east quickly later this evening) should keep snow amounts light, on the order of an inch or two. Much less favorable conditions across Lake Michigan, with more limited synoptic contribution, even lower inversion heights, and a noted inverted-v signature on guidance derived soundings. Can`t rule out a few lake effect snow showers into northwest lower Michigan, but both coverage and intensity will be minimal. Much more impactful concern tonight will be temperatures. Despite completely unfavorable radiational cooling conditions with gusty winds and lake clouds, simple magnitude of cold air advection will result in temperatures falling below freezing across the area (wind chill readings in the teens and 20s!). Freeze warning already issued for our vulnerable fruit growing areas along the northwest lower coastline. Unfortunately, next couple night look as cold, if not even a few degrees colder. && .SHORT TERM...(Tuesday through Thursday) Issued at 252 PM EDT Mon Apr 19 2021 High impact weather potential: Freeze conditions possible. Broad upper-level troughing will continue over the Great Lakes region although surface high pressure will build into the forecast area along with drier air. This will produce mostly quiet weather throughout this forecast period...with partly to mostly cloudy skies and cool weather as a generally north to northwesterly wind continues to usher in cooler air from Canada. With -10 to -12C still at 850mb, lingering moisture, and lake temperatures around 3C, we can expect lake clouds to be a nuisance through at least late Wednesday. Thursday will get a bit warmer as warmer air begins to wrap around the top of the ridge and spill into northern Michigan. As mentioned above, mostly north to northwesterly flow will continue to usher in cold temperatures through Wednesday, producing daytime temperatures well below normal for this time of the year...some locations will continue to run about 10-15 degrees below normal, only reaching into the mid 30s to low 40s. Temperatures will continue to only reach into the low 20s to low 30s at night...with the possibility of getting colder if clouds diminish and winds stay down in intensity. Will have to protect sensitive vegetation since a lot has blossomed and/or bloomed already...which is way too early, we still have a lot of cold nights in store for the next several weeks. .LONG TERM...(Thursday night through Monday) Issued at 252 PM EDT Mon Apr 19 2021 A rather progressive weather pattern will continue, but no "big storms" at the moment. Forecast models are in fairly good consensus of northern Michigan seeing more dry weather with mostly high pressure overhead and only a couple of periods with a weak disturbance moving through, producing some chances of precipitation. More seasonable temperatures should return for the long term forecast period as a more southerly flow develops. Overnight temperatures will drop into the 30s. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 700 PM EDT Mon Apr 19 2021 Unseasonably cold air will continue to sweep into Northern Michigan tonight thru Tuesday night in the wake of a cold front that passed thru our region during the day. Deep cyclonic flow... ample low level moisture and sufficiently cold air to produce over-lake instability will result in plenty of low clouds and MVFR/low VFR cigs as well as lake effect rain and snow showers. Most persistent shower activity will be between PLN and TVC as showers are pushed inland under the direction of W/NW low level flow. Surface winds will remain gusty from the W/NW at 15 to 25 kts thru the 24 hour TAF forecast period. && .MARINE... Issued at 252 PM EDT Mon Apr 19 2021 A tight pressure gradient and unstable over-water thermal regime will continue to bring advisory and low end gale force winds to the nearshore waters tonight...with some advisory winds lingering right through Tuesday. Expect wind speeds to decrease below advisory levels Tuesday night as the pressure gradient slackens. && .APX WATCHES/WARNINGS/ADVISORIES... MI...FREEZE WARNING until noon EDT Tuesday for MIZ020-021-025-026-031- 099. LH...SMALL CRAFT ADVISORY until 6 AM EDT Tuesday for LHZ348-349. GALE WARNING until 6 AM EDT Tuesday for LHZ345>347. LM...SMALL CRAFT ADVISORY until 6 AM EDT Tuesday for LMZ323-344>346. GALE WARNING until 6 AM EDT Tuesday for LMZ341-342. LS...SMALL CRAFT ADVISORY until 5 PM EDT Tuesday for LSZ322. GALE WARNING until 6 AM EDT Tuesday for LSZ321. && $$ UPDATE...MR NEAR TERM...MB SHORT TERM...TL LONG TERM...TL AVIATION...MR MARINE...MB
Area Forecast Discussion
National Weather Service Corpus Christi TX
650 PM CDT Mon Apr 19 2021 .DISCUSSION... Just a quick update this evening to increase POPs a bit across the Victoria Crossroads for the next few hours as radar activity has trended up recently. Activity will taper off through the evening hours as an upper level disturbance shifts off to the east and drier air filters in. && .PREV DISCUSSION... /Issued 613 PM CDT Mon Apr 19 2021/ AVIATION /00Z TAFs/... VFR conditions are currently prevailing across the region with OVC deck in place around 8000-10000 feet. Isolated showers across the Victoria Crossroads will taper off over the next several hours. Winds will become light and variable overnight which will open up a window for fog to develop across ALI/COT/LRD with brief MVFR ceilings/visibilities possible by 10-13Z. Overall, confidence is fairly low with the fog potential as models are backing off on the depth of the shallow moist layer. VFR conditions return by mid morning as south-southeasterly winds begin to increase to around 10 knots. PREV DISCUSSION... /Issued 331 PM CDT Mon Apr 19 2021/ SHORT TERM (Tonight through Tuesday Night)... The upper level trough (500 mb) will continue to move across the region this evening (additional upper forcing provided by a subtropical jet streak), followed by synoptic scale descent/drying. Will maintain less than 20 percent chance for showers near the coast/offshore this evening, then dry over the CWA by 06z Tuesday. Will forecast patchy fog over the WRN CWA 09-14z Tuesday owing to light/variable wind and thermodynamic profile conducive to radiation fog (per the NAM deterministic.) A cold front has entered the Southern Plains and is expected to continue SWD movement owing to an upper disturbance predicted to move EWD across the Plains to the Great Lakes/Mississippi Valley during the period. This front is expected to enter the CWA Tuesday night. However, limited moisture will preclude significant precipitation along the front (although the RAP moisture convergence along the front increases PWAT values to near normal values, the NAM/GFS do not). Temperatures during the period similar to the SREF mean values. LONG TERM (Wednesday through Monday)... The reinforcing cold front ushering a dry and cool Canadian airmass will be south of the area by Wednesday morning. The subtropical jet stream and broad upper-level ridging from a high pressure system over Central America, will shift northeastward over Texas through the work week. Meanwhile, an upper-level trough over the western CONUS will swing over the Central CONUS Friday. The polar and sub- tropical jet stack over one another Thursday night into Friday, allowing for favorable upper-level dynamics over portions of Texas. While these features are going on in the upper-levels, the surface is also playing a role; a surface low pressure begins to develop over the Rio Grande Plains Wednesday afternoon before being ingested into the main surface low over the Four Corners Wednesday night. The development of the surface low will cause the cold front to slowly retreat northward as a warm front. The warm front will be nearly stationary over the CWA through Thursday before accelerating northward Thursday night into Friday. Isentropic lift and sufficient low-level moisture will allow isolated to scattered showers to develop Thursday through Thursday night. An increase in elevated CAPE could squeeze out a few thunderstorms Thursday night so kept with the previous forecast. How`s the model agreement and what are the differences? The NAM, being a higher resolution short-term model, develops a surface low over Deep South Texas through the day Thursday. The latest 12Z GFS has also hinted at developing a surface trough over the same area and time. If a surface trough or low does develop over or just south of the area on Thursday, this will hinder the front from proceeding northward and increase rain chances on Thursday. The ECMWF and CMC pushes the warm front northward of the region, lowering QPFs. In either case, South Texas will be located in the warm sector of an approaching pacific front caused by an advancing mid to upper-level trough. Significant moisture (PWATs near 2.0"), CAPE values 1500-2500 J/kg, a weak cap, approaching mid and upper-level trough inducing positive vorticity, isentropic lift, and near the right entrance region of the subtropical jet, all favor the potential for strong to severe storms Friday afternoon into the early evening. Scattered to numerous showers and thunderstorms remain possible through the day on Friday, with the greatest threat expected over the Victoria Crossroads. The SPC has already included a 15% severe risk for areas just north of our CWA, this area will likely be changed before the onset of the event. Convection becomes less likely Friday night as the cap strengthens and disturbance moves eastward. There does lie some uncertainty on how fast the disturbance progresses eastward. The GFS and CMC develops a steep/strong trough that is about 6-12 hours slower than the more zonal ECMWF trough. According to the WPC and previous forecaster, the GFS has been trending more towards the faster solution of the ECMWF. Therefore, have put more weight on PoPs decreasing to slight chances late Friday night. This time period will be very important to focus on and relay any changes to patterns and/or trends. A pacific front with dry air following is expected to pass through overnight Friday night into Saturday morning. Dry conditions will be in place Saturday and Sunday with onshore flow returning Sunday. Highs are expected to stay in the 70s Wednesday and Thursday, then warm into the 80s and 90s Friday through the weekend as WAA increases with the northward push of the warm front. Lows in the mid 50s to mid 60s Wednesday night will warm well into the 60s for the remainder of the period. MARINE... In response to an upper level disturbance, isolated showers, with no significant accumulation, anticipated 00-09z Tuesday before significant drying/synoptic scale descent as the upper system moves east. A cold front will approach the waters Tuesday night yet no significant precipitation along the boundary due to limited moisture. Moderate northeasterly winds continue through early evening Wednesday before shifting by Thursday morning as the cold front retreats northward as a warm front. Moderate to strong southeasterly flow will dominate Thursday through Friday night in advance of a pacific front with dry winds in its wake. Small Craft Advisory conditions are possible Friday through Friday night over the offshore waters. Weak to moderate northwesterly winds Saturday morning will shift back onshore by Sunday. Isolated to scattered showers and thunderstorms are possible Thursday night through Friday night. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 57 80 55 72 63 / 10 0 0 0 0 Victoria 53 81 48 73 55 / 20 0 0 0 0 Laredo 56 86 58 77 63 / 0 0 0 0 20 Alice 53 84 55 74 60 / 10 0 0 0 10 Rockport 61 75 57 70 64 / 10 0 0 0 0 Cotulla 54 86 53 77 61 / 0 0 0 0 10 Kingsville 55 83 56 72 62 / 10 0 0 0 10 Navy Corpus 63 74 59 69 66 / 10 0 0 0 0 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ TC/95...SHORT TERM
Area Forecast Discussion
National Weather Service Cheyenne WY
506 PM MDT Mon Apr 19 2021 .SHORT TERM...(This evening through Tuesday) Issued at 251 PM MDT Mon Apr 19 2021 Current satellite and surface observations indicates that most of the frontal boundary has dug southwards into the Eastern Plains of Colorado. Widespread light snow as developed across much of the CWA. Main concern from now till around 6pm is the current forecast soundings. The dendritic growth with the soundings do not show good saturation layer until around 5pm tonight. This has drastically cut into our snowfall totals, resulting in a range of mixed precipitation to light snow throughout the day. Still expecting some snowfall during that time period with possible light to moderate snow in the southern portion of the CWA. Looking into the next couple of days, colder temperatures are expected in the wake of the frontal passages, with nighttime lows in the mid to low teens during both days. Daytime highs also do not recovery very quickly keeping southeastern Wyoming and the Nebraska Panhandle in the mid 30s to low 40s. This is mostly the result of a longwave positively tilted trough remaining over the northern and central plains, keeping the CWA in cold northwesterly flow. Next chance for precipitation is for Tuesday afternoon as an upper level disturbance pushes south over the northern Panhandle and again on Wednesday with a closed low setting up in the Four Corners region. The disturbance on Tuesday will mostly target the northeast portion of the Panhandle, with the closed low targeting the southern portion of the CWA. There is not a lot of snow expected with both these system, with the higher terrains receiving a bit more. .LONG TERM...(Tuesday night through Monday) Issued at 251 PM MDT Mon Apr 19 2021 A series of 500 mb open wave lows will pulse through southwest Wyoming and the western Nebraska Panhandle, bringing periods of moisture to the region. Each pulse, Thursday though Saturday, will be fast-moving and seem to only bring light precipitation to the region each time. One exception to that is the combination of energy from both the north and south for Friday`s system - there may be enough combined vorticity and CAPE for thunderstorms to be brought into the forecast, so it was. A warming trend will also occur during this Thursday through Saturday`s time period, with high temperatures finally making back to normal for the time of year by Saturday. The weekend looks quite a bit drier as a high amplitude ridge builds into the region, bringing highs about 10 degrees above normal into the 60s and 670s, and afternoon humidity down into the teens and 20s...enough to cause an increase in fire weather concerns. Looking upstream, a deep closed- low off the Pacific Coastline is the cause of that high amplitude ridge...and will eventually bring cold and unsettled weather to the && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 502 PM MDT Mon Apr 19 2021 Snow and low flight conditions will slowly come to an end this evening as conditions improve from north to south. HRRR and latest LAMP guidance was used for timing. Last terminal to clear out will be KCYS this evening as winds shift westerly. VFR conditions for all terminals shortly after 08Z tonight. && .FIRE WEATHER... Issued at 251 PM MDT Mon Apr 19 2021 No fire weather concerns this week due to widespread snowfall today, and cold temperatures through early Thursday morning. Models are indicating a warming and drying trend for next weekend, which may result in increasing fire weather concerns across portions of the region. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Winter Weather Advisory until 6 PM MDT this evening for WYZ101- 102. Winter Weather Advisory until 11 PM MDT this evening for WYZ103- 105>108-110-114-115-117>119. Winter Storm Warning until 3 AM MDT Tuesday for WYZ116. NE...Winter Weather Advisory until 6 PM MDT this evening for NEZ002- 095. Winter Weather Advisory until 11 PM MDT this evening for NEZ020- 054. && $$ SHORT TERM...MD LONG TERM...AB AVIATION...GCC FIRE WEATHER...TJT/MD
National Weather Service Eureka CA
245 PM PDT Mon Apr 19 2021 .SYNOPSIS...Dry weather is expected to prevail through the work week before widespread rain chances increase this weekend. Interior daytime temperatures will generally remain above normal during the week. Some interior valleys will continue to be chilly during the early mornings. A passing disturbance will bring drizzle to portions of Humboldt County tonight into Tuesday morning. Isolated showers and thunderstorms will also be possible over Lake, northeast Mendocino and eastern Trinity Counties during the afternoon on Tuesday. && .DISCUSSION...A transient upper level trough will induce a deeper marine layer with possible drizzle tonight through Tuesday morning. Cooler temperatures are expected for the interior on Tuesday as this shortwave trough traverses across the area. Cooling aloft associated with the trough will create sufficient instability during the day on Tuesday for possible showers and thunderstorms over the higher elevations of eastern Trinity, northeastern Mendocino and northern Lake counties. Convective allowing models, HRRR and NAM-nest, indicate convection developing as early as late tonight in Siskiyou County as a speed max traverses over Cape Mendocino. Warp around showers with the upper low may spread into the Trinity horn region around daybreak. Steeper mid-level lapse rates and greater instability is forecast to develop with daytime heating on Tuesday in the wrap around NE flow behind the upper low. The environment is quite dry with precipitable water values forecast to reach 0.50 to 0.60 inches by afternoon. NAM BUFKIT soundings has CAPE values peaking near 230J/KG with equilibrium levels near 20kft Tuesday afternoon. SREF calibrated tstm probabilities are only around 5%, while HREF neighborhood probabilities increase during the afternoon primarily over eastern Mendocino and Lake counties. Confidence we will see storms is not high, however there are sufficient indicators that storms (albeit weak ones) will be possible for the higher terrain of eastern Mendocino, southeastern Trinity and northern Lake Counties Tuesday afternoon. Warming is expected in the interior during the latter half of this week as a ridge aloft builds toward the area. GEFS 500mb means and deterministic GFS has another weak trough dropping down over the area in dry northerly flow on Wed. This shortwave is not as pronounced in ECMWF 500mb mean and deterministic solution. If the upper trough lingers over the area longer, slower warming will be the end result. Also, cooler overnight low temperatures with possible early morning frost in the interior valleys will be a distinct possibility. Coastal areas will not see any significant warming, due to the persistent northerly winds offshore and the steady influx of cool marine air each afternoon. Ensemble guidance and cluster analysis continue to indicate rain probabilities increasing through the weekend. There is still about 40% variance on the timing and a lesser variance on the depth of the cold core trough. Multi-model calibrated ensemble indicates 40-60% chance for a tenth of an inch of rain or more over the weekend centered on the 24hr period from Saturday night through Sunday afternoon. This rain will likely be in the beneficial category even though there are subtle hints we could see convection once the cold core aloft arrives early next week (Mon or Tue). && .AVIATION...Brief clearing at many coastal locations this afternoon will quickly be replaced by stratus once again as a deep saturated marine layer spreads inland across coastal Humboldt/Del Norte Counties, as well as portions of Mendocino County. Locally strong ascent due to strengthening low-level northwesterly flow near and upwind from the King Range will also favor drizzle across much of the Humboldt Bay area tonight, including KACV. Farther south at KUKI, the marine layer is forecast to be sufficiently deep to spread east across the coastal hills/ridges, such that IFR/LIFR ceilings may develop across Ukiah toward 12Z/20th. && .MARINE...Little change in the marine forecast this afternoon. Surface high pressure over the NERN PAC is on track to strengthen during the next 24 hours. The pressure gradient will tighten in the vicinity of coastal NWRN CA and aid in the development of small craft northerlies across all coastal waters by late this evening. Winds are forecast to strengthen further to gale force over the outer waters, and recent hires guidance is indicating these winds pulling closer to the coast in the southern inners and locally near Pt. Saint George by Tuesday afternoon. Have extended the gale warning into the southern inners during Tuesday in response. Gusty north winds and steep hazardous seas will persist through Wednesday. Winds and seas are then forecast to weaken during the second half of the week. && .EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 2 AM Tuesday to 11 PM PDT Wednesday for PZZ450. Small Craft Advisory from 5 PM this afternoon to 11 AM PDT Tuesday for PZZ470. Gale Warning from 11 AM Tuesday to 11 PM PDT Wednesday for PZZ470. Small Craft Advisory until 11 PM PDT Wednesday for PZZ455. Small Craft Advisory until 5 AM PDT Tuesday for PZZ475. Gale Warning from 5 AM Tuesday to 11 PM PDT Wednesday for PZZ475. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion
National Weather Service Marquette MI
803 PM EDT Mon Apr 19 2021 .SHORT TERM...(This evening through Tuesday) Issued at 428 PM EDT MON APR 19 2021 Water vapor imagery and RAP analysis show that the shortwave trof that was approaching the Upper Lakes 24hrs ago has deepened and closed off a mid-level low centered over far northern Lake Superior. Sfc low pres is located near Michipicoten Island and will be exiting the lake shortly. On the backside of the low, narrow 850mb thermal trof (-12C) is wrapping s across nw Upper MI. Sharply cyclonic low- level flow within this thermal trof combined with deep moisture has resulted in a recent increase in lake enhanced snow across nw Upper MI. KMQT radar shows some of this enhanced shsn activity spreading se into Marquette/Iron counties. Looks like a little instability from limited daytime heating is assisting in expanding -shsn/flurries even farther s and se. As the 850mb thermal trof translates se over the next several hrs, snow will increase into the eastern fcst area this evening. In that area (Alger/Luce/northern Schoolcraft counties), expect snow accumulations this evening around an inch, locally up to 2. Conversely, shsn will diminish rather quickly over the w due to loss of deeper moisture, higher April sun angle working to build a deepening mixed layer upstream of the lake (hostile for LES), and 850mb temps moderating to around -10C, marginal for LES. Thus, expect ongoing shsn to diminish rapidly to little more than flurries, if even that, over the next several hrs. Overnight into Tue morning, 850mb temps fall back a little to -11 to -14C, lowest over the e half of Lake Superior. As a result, -shsn/flurries should redevelop or expand some over the western fcst area. Nothing more than a dusting expected. To the e, -shsn will continue, but with deeper moisture exiting, the -shsn will be lighter than what occurs during the evening hrs. May see another inch of snow overnight/Tue morning. Lows tonight should range from the upper teens to mid 20s, coldest interior w half. Flurries/-shsn should end by Tue aftn. Should be quite a bit of cloudiness around thru the day as daytime heating working on moisture off the lake leads to increased stratocu development across the entire fcst area. Expect high temps to range from the lwr 30s F n and e to the lwr 40s s central. .LONG TERM...(Tuesday night through Monday) Issued at 303 PM EDT MON APR 19 2021 A blocking pattern will continue this week over the northern Pacific with ridging extending from the western U.S though the Gulf of Alaska and north to the Arctic Circle, with strong positive 500mb height anomalies over AK. This will help maintain downstream troughing and negative 500mb height anomalies over central and northern Canada. Shortwave energy rotating around the trough will keep an active pattern over the U.P through next weekend. Temperatures will moderate as shortwave ridging takes hold on Thursday into Friday, ahead of what looks like a bit stronger shortwave trough. The shortwave and associated cold front look to come through the region on Saturday bringing a quick shot of cooler temperatures and precipitation. WPC fuzzy ensemble clusters are locked in with the strong Pacific ridging continuing through early next weekend. Ensembles clusters start to deviate thereafter and there are some indications the western blocking ridge may start to break down. Deterministic models show a shortwave moving through the northern Great Lakes Tuesday night with shortwave ridging building in Thursday. Not expecting much in the way of precipitation with the wave Tuesday night into Wednesday morning. 850mb temps cool a little bit, down to -13F which will induce some lake instability however the air is pretty dry with deep inverted v soundings. Temperatures will moderate with the ridging on Thursday though this ridge becomes flattened out by Friday as a weak shortwave passes to the south of the area. Thursday and Friday will probably be the warmest days in the extended. Models soundings show deep mixing on Thursday and Friday with RH dropping to around 25% for the counties along with wind gusts to around 20 mph, which could elevate fire weather conditions. The timing of the weekend system is still a bit uncertain. It is possible we squeak out a day of temperatures in the 40s and 50s for at least the central and east with the front arriving in the evening hours. Over the west, models bring the front in by early afternoon. Deterministic models still deviate on the timing and track of the system, with the Canadian furthest south and most aggressive with forcing and precipitation. The GFS keeps the strongest forcing north of the area and the ECMWF keeps the wave weaker with an elongated trough. NBM PoPs are pretty washed out likely due to the model timing and track differences with chance PoPs over much of the area Friday night through the day Saturday. It likely will be a much shorter window for precipitation and expecting PoPs will go up and the window will narrow with subsequent forecasts. Temperature profiles look like they could be cold enough for snow, at least in the west, with some slushy accumulations possible. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 742 PM EDT MON APR 19 2021 As low pres departs to the e and drier air begins to move into the area, expect improving conditions this evening with shsn diminishing. Gusty NW winds to 20-30kt will also subside. At KIWD, influx of drier air has already improved conditions to VFR and should remain that way through the period. At KCMX, expect conditions to vary btwn VFR and MVFR this evening before improving to VFR overnight into Tuesday. At KSAW, conditions will vary between IFR and MVFR early this evening before improving to MVFR by late evening and then to VFR Tue afternoon. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 428 PM EDT MON APR 19 2021 Ongoing nw gales across the e half of Lake Superior will diminish to 20-30kt by late evening as low pres heads for Quebec. Across western Lake Superior, expect wind gusts generally in the 20-25kt range. On Tue, winds will diminish to mostly under 15kt across western Lake Superior and to 15-25kt across the e. Winds will generally be blo 20kt on Wed. W to sw winds will increase on Thu, strongest over western Lake Superior where gusts to 25kt, perhaps to 30kt, should occur. Winds may diminish slightly for Fri, but will increase again late Sat (up to 30kt east) in the wake of a passing cold front. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Lakeshore Flood Advisory until 2 AM EDT Tuesday for MIZ006-007. Lake Superior... Gale Warning until 11 PM EDT this evening for LSZ249>251-266-267. Gale Warning until 8 PM EDT this evening for LSZ244-245-248-264- 265. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...NL AVIATION...Voss MARINE...Rolfson
Area Forecast Discussion
National Weather Service Mount Holly NJ
940 PM EDT Mon Apr 19 2021 .SYNOPSIS... A weak upper level wave will move out to sea overnight. A brief stint of high pressure will lead to a quiet Tuesday before a surface low organizes to our west. This low will pull a strong cold front across the region on Wednesday. High pressure will build eastward behind this system for the remainder of the week. && .NEAR TERM /THROUGH TUESDAY/... A mid level short wave trough was moving off our coast and out to sea this evening. It will continue to take most of the lingering clouds with it. Surface high pressure is forecast to nose into our region from the southwest overnight. As a result, we are anticipating a mostly clear sky and a light wind. Low temperatures should favor the 40s. Tuesday will be the nicest day of the week. With high pressure off the mid-Atlantic coast, strong WAA will be underway with a west to southwest flow. Could be a bit breezy, especially going into the afternoon, with winds generally 10-15 mph with gusts to 20 mph. Highs will generally be in the lower 70s throughout. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... The potential for severe weather continues Wednesday. A potent shortwave trough will dive southeast across the Midwest Tuesday night. A strengthening 250 mb jet just to our southwest will work in unison with this wave to promote strong cyclogenesis across the central Appalachians into Wednesday morning. With rather impressive PVA ahead of this wave and the aforementioned upper-level forcing, the large scale forcing will most certainly be in place for this feature. The northern origins of the trailing surface high from central Canada will usher in a seasonable cold airmass, which is expected to provide efficient surface lift along the cold front. While instability isn`t expected to be noticeably impressive, strong low-level (speed) shear will support the development of linear storm features. Hi-res guidance is currently forecasting 50-70 knots of 0- 3 km shear. Combined with up to 1000 J/kg of MLCAPE, this will be more than sufficient to support the development of linear storm segments. Completely agree with the 3 km NAM in the forecast of a long QLCS feature moving across the entire CWA early Wednesday afternoon. Waiting as we move into the HRRR and ARW time frames for added confidence but there is good agreement amongst the global guidance so don`t expect significant change at this point. A few showers and a rumble or two of thunder is possible, especially along and north of I-78 Wednesday morning. The more clearing that occurs, the better the surface heating and larger the instability that can be reached. A slower movement of the surface low, with a longer period for strengthening would likely lead to a greater severe threat as we would sit in the warm sector longer. This is one facet that remains to be worked out so to speak. Climatologically, small hail is possible with any of the storms, but strong to damaging winds will be the main risk with these storms. A strong 850 mb LLJ will advect ample moisture ahead of the front, which will lead to locally heavy downpours. Forward motion of the front should preclude widespread flooding, but can`t rule out localized urban and poor drainage flooding with half to locally one inch of rainfall. Highs Wednesday will warm into the upper 60s to the south, with low to mid 60s north of I-78. Clearer skies will lead to warmer highs. Temperatures will plummet behind the front with lows in the low to mid 30s by Thursday morning. A breezy night behind the front should prohibit frost, but went ahead and added patchy frost into areas where the frost-freeze program has started. More of a freeze potential as wind will work against frost potential. A much quieter and cooler day Thursday with highs in the upper 40s north to lower 50s south with partly cloudy skies. It will remain quite breezy with westerly winds gusts from 20 to 30 mph. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... The weather pattern looks to stay fairly busy through the long term as one system will continue to depart early in the period with a brief respite of fair weather Friday into Saturday before the next potential system arrives for later in the weekend. In terms of the details, it will remain a bit breezy Thursday night through Friday as deep low pressure continues to lift north through Atlantic Canada while high pressure sets up to our south. The airmass over the region moderates though so Friday looks to see seasonable temperatures under mainly sunny skies. Friday night into Saturday, high pressure moves off the east coast as an upper level trough moves in to our west with the next low developing near the SE CONUS. There is a lot of uncertainty regarding how this system tracks with the ECMWF and to a lesser degree the GFS have it moving up the coast and bringing widespread rain and gusty winds late Saturday, Saturday night, and into Sunday. Meanwhile the latest GEM is much weaker and surpressed and has the system missing us to the south. Didn`t deviate much from the NBM so am forecasting likely POPs for the majority of the area Saturday night which is when, according to current indications, the system look to make its closest pass. The aformentioned system should move out by late Sunday with dry weather looking to start next week. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Overnight...VFR under a mostly clear sky. Isolated areas of fog are possible but they will likely not affect the TAF sites. Southwest wind 6 knots or less, becoming variable at most locations. High confidence. Tuesday...VFR with scattered clouds. Southwest wind increasing to around 10 knots with gusts near 20 knots. High confidence. Outlook... Wednesday...VFR initially with sub-VFR conditions with showers and thunderstorms in the afternoon. A return to VFR near or after 00Z from west to east as a cold front crosses the region. Southwest winds from 10 to 15 knots with gusts from 25 to 30 knots. Winds turn westerly behind the front. Moderate confidence. Thursday...VFR with westerly winds from 15 to 20 knots and gusts from 25 to 30 knots. High confidence. Thursday night through Friday...Mainly VFR with W/NW winds 10 to 15 knots with gusts of 20 to 25 knots possible both Thursday evening and again by around midday Friday through the afternoon. High confidence. Friday night through Saturday...Mainly VFR with west winds around 5 knots Friday night becoming SW 5 to 10 knots Saturday. The next system could arrive very late in the day or at night bringing rain and associated restrictions. Moderate confidence. && .MARINE... Sub-Small Craft Advisory conditions on tap through Tuesday. SW winds 10-15 kt. Gusts up to 20 kt will develop Tuesday afternoon. Seas generally at or below 3 feet. Outlook... Wednesday...SCA conditions developing into the afternoon as southwesterly winds gust from 25 to 30 knots. Seas from 3 to 5 feet. Wednesday night and Thursday...Gale force wind gusts likely out of the northwest. Seas from 3 to 5 feet. Thursday night through Friday...SCA conditions likely Thursday night into early Friday before winds subside below SCA levels by late Friday. Friday night through Saturday...Conditions should be mainly tranquil on the seas through this period with Sub SCA winds/seas. However the next system could bring increasing winds and waves by Saturday night. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...None. && $$ Synopsis...Davis Near Term...Iovino/MPS Short Term...Davis Long Term...Fitzsimmons Aviation...Davis/Fitzsimmons/Iovino Marine...Davis/Fitzsimmons/MPS
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
552 PM MDT Mon Apr 19 2021 .UPDATE... Issued at 551 PM MDT Mon Apr 19 2021 Updated forecast to cancel the winter weather advisory that was in effect for the southern Black Hills and far southwestern South Dakota. && .DISCUSSION...(This Evening Through Monday) Issued at 149 PM MDT Mon Apr 19 2021 Broad trough covers the CONUS, with upper low spinning over the Hudson Bay. Water vapor indicates shortwave energy moving through the northern plains. Our CWA is between the right entrance region of one jet streak and the left exit region of another. Stratiform snow has shifted to the far southern portions of SD, but snow showers have developed across much of the area. With cold high pressure sinking into the region, winds are northerly 10 to 20 kts, and temperatures are in the 20s and 30s. Shortwave energy, along with lingering moisture and weak instability/steep lapse rates, will allow for snow showers to continue through tonight and Tuesday. Most places will see minimal accumulations. This afternoon and early evening, the southern Black Hills/foothills could receive a few more inches of snow due to downstream convergence. The northern Black Hills could continue to see some upslope enhancement; the HRRR Froude number is between 1 and 2 today through tonight. A few more inches of snow will be possible there through Tuesday afternoon. Warmer, drier air will move back into the region Wednesday and Thursday. Highs will warm into the 40s and 50s, beneath sunny skies. Models continue to show an upper wave and associated cold front crossing the northern plains Friday, bringing cooler temperatures and light rain/snow showers. A warming trend is then expected into early next week, beneath broad upper ridging. Deterministic models and ensembles are hinting at a longwave trough/low pressure system pushing into the central states towards the middle of next week, but it is too early to know how much moisture our area will receive from this system, or in what form. && .AVIATION...(For the 00Z TAFS Through 00Z Tuesday Evening) Issued At 443 PM MDT Mon Apr 19 2021 Isolated to scattered snow showers are expected over the plains through Tuesday with local IFR conditions at times. Scattered to numerous snow showers are expected over and near the Black Hills through Tuesday with areas of IFR/LIFR conditions at times. Outside of any snow showers, VFR/local MVFR conditions are expected. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Winter Weather Advisory until 6 PM MDT Tuesday for SDZ024-028. WY...Winter Weather Advisory until 6 PM MDT Tuesday for WYZ057. && $$ Update...10 DISCUSSION...Pojorlie AVIATION...10