textproduct: La Crosse

KEY MESSAGES

- Above normal temperatures continue through midweek with daytime highs in the 90s for much of the area through at least Wednesday. Duration and extent of warmest temperatures decreases in confidence into the weekend.

- Potential impact from Canadian wildfire smoke initially Thursday along northern peripheral counties in central Wisconsin, depending on exit of anomalous high pressure over the forecast area.

DISCUSSION

Issued at 1246 AM CDT Tue Jul 14 2026

Persistent Above Normal Temperatures:

An all-time record (SPC Climatology) mid-level (500mb) isoheight of 601 dam was observed in the 14.00Z RAOB at MPX, nearly aligning with the center of anticyclonic flow seen on GOES water vapor imagery loops over the central CONUS Tuesday night. Long term global ensembles and accompanying AI probabilities suggest these maximum percentile (594 dam) mid-level heights locally lingering and stretching along an axis from the Mississippi to Ohio River Valleys through midweek. While current forecast confidence for weakening of upper level heights abates the maximum percentile (SPC Climatology) 25C isotherm at 850mb locally through midweek, anomalous (90+ percentile - SPC Climatology) low level (850mb) temperatures quickly rebuild from the Central to Northern Plains as a suggestive area of cyclonic rotation on GOES upper level water vapor imagery is seen retrograding west through the Mid Mississippi River Valley, potentially causing a Rex Block centered over the Great Plains into the weekend. Widespread disagreement in longer term ensembles and their AI counterparts regarding local impacts with GFS/GEFS (13.18Z) dragging a deepening low pressure southeast through the area to start the weekend while the ECMWF/EPS (13.12Z) reigns higher heights supreme, limiting any probability in measurable precipitation and perpetuating higher temperatures. Resultant ensemble spread in daytime temperatures into the weekend spans from upper 70s (GEFS 13.12Z) to upper 80s/low 90s (EPS 13.12Z).

Potential Wildfire Smoke Impacts:

Impactful concentrations of Canadian wildfire smoke sag south through northern Wisconsin through Wednesday, potentially reaching the northern reaches of the forecast area through Thursday morning (HRRR 14.00Z). Current forecast confidence in the synoptic pattern places the local forecast area at the southern periphery of the higher concentrations and impacts, dependent on subsequent building heights through the Great Plains. The aforementioned EPS synoptic solution could abate higher concentrations along our northern periphery while the GEFS solution would drag smoke through the Upper Mississippi River Valley into the weekend. Therefore, have not included/added haze/smoke to the weather grids at the current forecast hour while select upstream, higher confidence neighboring forecast offices did.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 543 AM CDT Tue Jul 14 2026

Valley fog has taken over many of the local river valleys, including portions of the Mississippi River. Any locations with fog should see the fog dissipate over the next couple of hours. Mostly clear skies expected for the rest of the TAF period with another night of valley fog potential Tuesday night into Wednesday. Light and variable winds this morning shift to light west to southwest winds later this morning for the remainder of the day.

ARX WATCHES/WARNINGS/ADVISORIES

WI...Heat Advisory from noon today to 8 PM CDT Wednesday for WIZ053>055-061. Heat Advisory until 8 PM CDT Wednesday for WIZ032>034-041>044. Heat Advisory until 9 PM CDT this evening for WIZ017-029. MN...Heat Advisory from noon today to 8 PM CDT Wednesday for MNZ086>088-094>096. Heat Advisory until 8 PM CDT Wednesday for MNZ079. IA...Heat Advisory from noon today to 8 PM CDT Wednesday for IAZ010- 011-030.