MD 1658 CONCERNING HEAVY SNOW FOR CENTRAL…NORTH-CENTRAL AND NORTHEAST KS…SOUTHEAST NE…SOUTHWEST IA…AND NORTHWEST MO
Mesoscale Discussion 1658 NWS Storm Prediction Center Norman OK 0354 AM CST Sun Nov 25 2018 Areas affected...Central...north-central and northeast KS...southeast NE...southwest IA...and northwest MO Concerning...Heavy snow Valid 250954Z - 251600Z SUMMARY...Snowfall rates up to 1-2 inches per hour will increase from west to east during the late overnight through this morning. In addition to heavy snow, strengthening northerly winds through the morning will produce a blizzard with reduced visibilities in whiteout conditions. DISCUSSION...Short-term guidance remains consistent with the forecast for a vigorous shortwave trough, now located over eastern CO, to emerge eastward across KS overnight, with deepening of this system between 12-18Z as it reaches eastern KS/western MO by late morning. Trends in mosaic radar imagery showed a band of precipitation had developed from north-central KS to southeast NE. This corridor in the northern part of the discussion area is expected to be the first southwest-northeast oriented zone to change to snow and increase in rates as surface temperatures fall through the lower 30s to upper 20s F by 11-12Z. This same trend with snow developing across the rest of the discussion area after daybreak from central to northeast KS and far northwest MO to southwest IA will occur as the surface low shifts east-northeast into MO. This will allow low-level winds on its north-northwest periphery to back to northerly and strengthen, ushering in colder temperatures, and supporting a high likelihood for reduced visibilities in whiteout conditions. Meanwhile, an increase in upward vertical motion through the dendritic-growth zone per forecast soundings is expected as, 1) the shortwave trough deepens with eastward progression and 2) within the exit region of a strengthening 500-mb 100-kt jet spreading across northeast KS/northwest MO this morning. This factor which is expected to become stronger by 15-18Z suggests snowfall rates could be up to 2 inches per hour, generally north of a line from KSLN to KSTJ to 25 S KLWD, while the initial aforementioned band of snow could have rates up to 1 inch per hour. Forecast soundings also indicated weak elevated instability rooted around 600 mb, given the likelihood of steepening midlevel lapse rates (around 8 C/km) in the exit region of the midlevel jet. This could enhance snowfall rates. ..Peters.. 11/25/2018 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...DMX...EAX...OAX...TOP...ICT...GID...DDC...GLD... LAT...LON 41259537 41359315 41159252 40309380 39249539 38409689 38239774 38379854 38699916 38909976 39289995 39479979 40099877 40489775 40979632 41259537
from SPC Mesoscale Discussions http://bit.ly/2QgK4f6
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