textproduct: Springfield

KEY MESSAGES

- Confidence increasing in multiple rounds of heavy rainfall and potentially significant flooding late this week into the weekend, especially in south-central Missouri. Friday into Saturday look to be the most impactful days. A Flood Watch is in effect.

- A Slight (2 of 5) Risk of Severe Storms persists from Thursday evening into Friday night, especially southeast of the Interstate 44 corridor. Large hail will be the primary potential severe weather hazard.

SHORT TERM /THROUGH TONIGHT/

Issued at 340 PM CDT Wed Apr 2 2025

Synoptic Pattern and Current Conditions:

Water vapor imagery depicts a deep trough over the western U.S. with a potent short wave trough ejecting northeast through the Upper Mississippi Valley. Surface low pressure is tracking northeast through the Corn Belt with a cold front trailing south from the low through western Missouri and into the Arklatex. Ahead of the front, the risk for severe storms will persist through late afternoon. See the Mesoscale Discussion above for more details and reasoning on particular hazards.

Tonight:

That front will continue to shift east and southeast of the Missouri Ozarks. By 12Z, the front will extend from the Missouri Bootheel to the Little Rock area. Tonight largely looks dry as weak surface high pressure builds in from the northwest. The one exception may be locations near the Arkansas border as isentropic upglide (305-310 K layer) overspreads the area after 09Z. This could result in a few light showers across far southern Missouri (20-30% chance).

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 340 PM CDT Wed Apr 2 2025

Thursday and Thursday Night:

Short term ensembles show good agreement that a 850 mb front will strengthen and lift north into south-central and southeastern Missouri by 00Z on Friday. The 850 mb front will then continue to slowly lift north Thursday night. This frontal lifting scenario is supported as we become positioned beneath the left-entrance region of an upper-level jet streak. This will support increasing coverage of rain showers with scattered thunderstorms also favored by afternoon as MUCAPE values increase into the 500-1000 J/kg range (highest values south). We could see a marginal severe hail risk develop by late afternoon across far southern Missouri with that threat persisting into Thursday night.

Rainfall amounts from Thursday into Thursday night do not look overly concerning with HREF LPMM products indicating amounts in the 0.25" to 0.75" range. HREF 90th percentile and max values do approach 2.00" in some pockets, especially across south-central Missouri. We will therefore leave the start time of the Flood Watch intact as some localized flash flooding could occur. Even if this worst case scenario was to occur, flash flooding would largely be confined to typical low water crossings.

Heavy Rainfall Setup Friday and Saturday:

Global ensembles remain consistent in depicting a pattern similar to the Maddox Synoptic heavy rainfall scenario. This includes a deep, slow moving upper-level trough, anonymously moist low-level flow, and a quasi-stationary surface front. The one difference from the Maddox Synoptic pattern will be that strong wind shear will be present in the 850-300 mb layer.

Both the ECMWF and NAEFS products continue to indicate precipitable water values and specific humidities near or exceeding 30-year (1979-2009) climatological maxes. Integrated vapor transport is also approaching maxes with thresholds for an atmospheric river event (Gulf of America source region) being met.

In the low-levels, there is still model variance regarding where the frontal zone will set up. There is strong consensus that it will shift north from Friday into Friday night as strong short wave energy emerges across the southern Plains from a closed low across the Desert Southwest. To complicate matters, thunderstorm cold pools will also impact the eventual location of the front.

With this being said, our confidence remains high that areas southeast of the I-44 corridor will see a significant amount of rainfall from Friday into Saturday with an increasing risk for flooding and flash flooding. Confidence decreases slightly along the I-44 corridor given the uncertainties in frontal position, however this region is still expected to receive appreciable rainfall.

Potential Amounts and Impacts:

Understanding that the bulk of this event is still not in the envelop of CAMs, the following values are almost exclusively reliant on global deterministic models and ensembles. As mentioned earlier, thunderstorm cold pools and smaller scale features in general could have significant effects on eventual rainfall amounts. With that being said, here are NBM percentiles for 72-hour rainfall.

Most likely scenario (25th to 75th percentile):

SE KS/west-central MO: 1.50" to 4.00" I-44 corridor: 2.50" to 5.50" South-central MO: 4.50" to 7.50"

Localized amounts up to (90th percentile):

SE KS/west-central MO: 5.00" I-44 corridor: 7.50" South-central MO: 9.50"

Amounts that push the 75th to 90th percentile across south-central Missouri would result in a significant flooding and flash flooding threat. This includes significant rises on rivers with the potential for levels getting into the Moderate Flood category. We have included a Hydro section below to specifically discuss expectations with rivers.

Note: Additional accumulation information including probabilities of exceedance graphics can be found in our DSS packet:

weather.gov/media/sgf/DssPacket.pdf

Severe Thunderstorm Potential Friday and Saturday:

A Slight Risk for severe thunderstorms will persist, especially on Friday and Friday night across southern Missouri. The main potential hazard will continue to be large hail given ample amounts of elevated instability and deep layer shear. The eventual location of that surface front and the amount of near-surface destabilization will be big players regarding the potential for surface-based convection and any sort of straight-line wind and/or tornado threat. This will be a short-term forecast challenge.

Potential for Snow Late Saturday Night and Early Sunday Morning:

Global models track an upper level short wave trough out of the southern Plains and through the Ozarks region. The combination of surface temperatures in the 30s and rapidly cooling low/mid levels will be supportive of snowflakes if precipitation can persist. Accumulations would be very limited at best given warm ground temperatures.

Much Cooler with Frost Potential Early Next Week:

Five wave charts and global ensembles indicate a northwesterly flow setting up across the region. Below normal temperatures and dry conditions will be the result. The potential for a frost/freeze continues to increase for a few nights early next week. The coldest night may be Monday night as Canadian high pressure builds south into the Middle Mississippi Valley. Given that the growing season has started, frost/freeze headlines appear likely.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1240 AM CDT Thu Apr 3 2025

A brief period of calm VFR conditions will prevail through 12-14Z. Afterwards, widespread rain showers and thunderstorms will move into the area for much of the period (60-90% chance). It's difficult to pinpoint exactly when lulls and the heaviest precipitation will be, so have included TEMPOs for much of the time to signify that there will be periods of heavier showers as well as periods of no showers at all. The bottom line is that through the whole period, widespread rain/showers will be in and around the area. The best chance for thunderstorms will be after 18Z as elevated instability increases across the area. There is the low-end potential (5% chance) for some thunderstorms to produce small hail up to quarter size, especially at BBG.

Otherwise, cigs will slowly deteriorate to MVFR through the period as winds stay modest out of the east. Some gusts up to 20-25 kts may occur, but rather infrequently.

HYDROLOGY

Issued at 340 PM CDT Wed Apr 2 2025

River Expectations and Forecasts:

Abnormally Dry or Drought conditions exist across much of the CWA as evidenced by below normal soil moisture and normal to below normal streamflow. Despite the relatively dry antecedent moisture conditions coming into this event, forecast rainfall amounts will be enough to saturate soils and generate rises on area waterways.

RFC forecasts are showing significant rises to many rivers in the Flood Watch area. Locations along the Jacks Fork and Current River are currently expected to reach Moderate flood stage. Further north, the Gasconade River and some major tributaries are also expected to exceed flood stage with the Big Piney expected to reach Moderate Flood stage.

Further west, the James River is expected to rise approaching or exceeding flood stage as well as the North fork White River.

Important Note: River Forecasts only include precipitation out to 72 hours (Saturday morning) and additional accumulating rainfall on Saturday may cause additional rises.

SGF WATCHES/WARNINGS/ADVISORIES

KS...None. MO...Flood Watch from 7 AM CDT this morning through Saturday evening for MOZ070-071-081>083-090>092-095>098-102>106.