Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0221 AM CDT Fri Jun 30 2017 Valid 021200Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NEBRASKA AND IOWA... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OUTSIDE OF THE SLIGHT RISK AREA ACROSS PARTS OF THE GREAT PLAINS...OZARKS...MID MISSOURI VALLEY AND WESTERN GREAT LAKES... ...SUMMARY... Severe thunderstorms with large hail and wind damage will be possible across parts of the Nebraska eastward across Iowa. Marginally severe thunderstorms will be possible southward across the central Plains into Oklahoma and the Ozarks. ...Central Plains/Mid Missouri Valley... An upper-level trough is forecast to move southeastward across the upper Mississippi Valley and mid Missouri Valley on Sunday. At the surface, a cold front is forecast to advance southward into Nebraska and Iowa on Sunday with surface dewpoints ahead of the front in the mid to upper 60s F. This should result in an east-to-west corridor of moderate instability across Nebraska and Iowa by afternoon. Thunderstorms are forecast to initiate along the front and move southeastward across the slight risk area from the mid afternoon into the early evening. In addition to moderate instability, forecast soundings along the front at 00Z/Monday show steep low-level lapse rates, 0-6 km shear in the 30 to 40 kt range and 500 mb temperatures around -10C. This should support supercell development in the late afternoon with isolated large hail. The greatest threat for large hail is forecast to be across Nebraska where mid-level lapse rates should be the steepest. Wind damage will also be possible especially during the early to mid evening when linear will be the most likely storm mode. A severe threat will also be possible further west-northwest in the Black Hills vicinity and eastward toward Chicago but weaker instability in those two areas should keep the severe threat marginal. ...Southern Plains/Ozarks... The southern extension of an upper-level trough is forecast to move into the Ozarks on Sunday. At the surface, a corridor of maximized low-level moisture should be in place from the central Plains extending southeastward into the Ozarks, along which isolated thunderstorms may develop during the afternoon. Steep low-level lapse rates may contribute to a wind-damage threat mainly where storms have access to the strongest instability. Due to warm air aloft, the window for convection could be narrow and storms may struggle even after initiation. For this reason, any severe threat is expected to remain marginal. ..Broyles.. 06/30/2017Read more
from SPC Forecast Products http://ift.tt/GAMjPN
No comments:
Post a Comment