Tropical humidity surges, scattered nocturnal storms

Welcome to Havana. With lefse.

Our stiff southerly tempest has blown in a tropical air mass. Dew points surged as moisture rich air returned Minnesota. The moisture tongue is clearly visible on the GOES 2 km satellite image with dew points overlaid.

The high dew point air mass, and a strong low level jet stream about 5,000 feet above ground level are fuel for scattered storms as we move through the overnight hours into Thursday.

The National Oceanic and Atmospheric Administration's Storm Prediction Center has upgraded the risk zone over eastern Minnesota and Wisconsin into the "slight" risk category, up from marginal.

Here's the inside baseball weather geekage on the upgrade to a slight risk Thursday from NOAA's convective outlook.

WHILE CONVECTIVE MODE MAY EVOLVE INTO A LINEAR CONFIGURATION RELATIVELY

QUICKLY ALONG THE ADVANCING FRONT...A FEW SUPERCELLS MAY EXIST -- BOTH WITH INITIAL UPDRAFT DEVELOPMENT AND LATER EMBEDDED WITHIN AN EVOLVING LINE OF STORMS. GIVEN ASSOCIATED LIKELIHOOD FOR AT LEAST ISOLATED RISK FOR HAIL AND DAMAGING WINDS -- AND PERHAPS A TORNADO

-- WITH A FEW OF THE MORE ROBUST CONVECTIVE ELEMENTS...AN UPGRADE TO SLIGHT RISK IS BEING INTRODUCED ATTM ACROSS THE UPPER MS VALLEY VICINITY.

Storm timing favors a couple of advancing waves of thunderstorms over overnight and Thursday. Scattered storms roll through Wednesday evening. Nocturnal low level jet streams likely drive storms overnight.

The advancing cold front triggers another developing line Thursday while sweeping east.

Expect scattered, strong thunderstorms through Thursday with some follow on showers Friday after the cool front. The reward? Another spectacular Minnesota September weekend.