Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Mon Jan 09 2023 16:24:21 AWUS01 KWNH 091624 FFGMPD CAZ000-100230- Mesoscale Precipitation Discussion 0032 NWS Weather Prediction Center College Park MD 1123 AM EST Mon Jan 09 2023 Areas affected...Central Coastal to western Transverse Ranges of California... Concerning...Heavy rainfall...Flash flooding likely Valid 091630Z - 100230Z SUMMARY...Core of Strong to Very Strong AR coming ashore. Flash flooding is likely within burn scars given hourly rates up to 1-1.25"/hr in Central CA Coastal range and additional totals of 6-8". Plume will start moving south after 21z and increase exposure to Transverse Ranges with 3-5" totals possible through 03z. DISCUSSION...GOES-W WV suite depicts strong negative tilt trof swinging to almost E-W just north of 40N while the next amplifying shortwave at the base is starting to show baroclinic leaf development west of 130W north of 30N. The spacing between is along the south side of a 130kt 250mb jet streak with very strong vorticity gradient and some weak short-wave ridging crossing the central CA coastline. This is generally coincident with the warm front that has started to surge ashore across Santa Cruz/Santa Lucia Range and through SBP. This is allowing for strong WAA and moisture surge through the coastal terrain along a 50-60kt jet per VWP from DAX to VBP and RAP analysis. CIRA LPW shows nose of ..6-.7" sfc-850mb and .3-.4" 850-700mb moisture intersecting the coast. This has resulted in record total PWAT values at OAK and VBG this morning with 1.3" and 1.25" and generally running slight below greatest moisture values for this part of the month.=20 Combined with the strong deep flow, IVT values are over 800 kg/m/s occasionally ticking to 1000 kg/m/s. As such, rainfall rates in the orthogonal intersection across the Santa Lucia Range have been observed as high as 1.25", with average values in the .75", resulting in mudslides and rockfalls reported even into the Diablo range and .5-.75" in the Santa Cruz Range as well. Given the distance upstream of the height-falls approaching shortwave, there is going to be very limited southward push of the core of the AR through 21z resulting in additional 6-8" totals by 00z and likely continued considerable flash flooding conditions. After 21z, the shortwave will approach, this is already starting to show signs of severing the subtropical connection to the deeper moisture source and narrowing the plume of 1.5" TPW seen well upstream. Less unidirectional flow will reduce winds slightly but maintain 750-850 IVT values toward 00-03z as the cold front/AR plume round Cape Conception. This will rapidly increase favorable orientation to the Santa Ynez, Sierra Madre and into the downstream Transverse Ranges in Ventura and Los Angles county.=20 While winds/moisture will decrease, the slope of orographic ascent should increase slightly and slightly reduced rates of .5-.75" will be expected between 00-03z in favored terrain, totaling to 3-5" by 03z (with more to come after). Soil conditions are slightly better further south given some time to recover over the past few days with 0-40cm relative soil saturation ratios ranging from 60-75% versus near full saturation further north. As such, flash flooding and mud slides, remain possible, but should be a bit less in magnitude and coverage relative to further north.=20=20 Gallina ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!58lVzYCyp3xdaBrmb2tW8-Jyvo-29U1nAiBtkajvp8Wrv3kBorGH5CftbnPh4ZWcDifP= O945pk1neyPTcTQRfmptd8s$ for graphic product... ATTN...WFO...HNX...LOX...MTR...STO... ATTN...RFC...CNRFC...NWC... LAT...LON 38312272 38232169 36882116 35852034 35021955=20 34741856 34091866 33911949 33892022 34272090=20 34802111 35552156 36172210 36732248 37622304=20 =20=20=20=20=20=20=20=20=20=20=20=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .