146

FXUS63 KSGF 022330

AFDSGF



Area Forecast Discussion

National Weather Service Springfield MO

630 PM CDT Wed Apr 2 2025



.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 /THURSDAY 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 /00Z TAFS THROUGH 00Z THURSDAY/...

Issued at 630 PM CDT Wed Apr 2 2025



The storm system that brought the showers and storms to the area

early today has moved off to the east. Winds may remain gusty

very early this evening but will weaken and become variable

later this evening into tonight, then will become move east to

northeasterly on Thursday and could be gusty at times. Rain

chances will start to move from north to south Thursday morning

into Thursday afternoon. A few embedded thunderstorms will be

possible Thursday afternoon into the evening hours. MVFR

ceilings will be possible Thursday afternoon with lower

visibilities with any of the heavier showers and storms.



&&



.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 Thursday morning through Saturday evening for

     MOZ070-071-081>083-090>092-095>098-102>106.



&&



$$



SHORT TERM...Schaumann

LONG TERM...Schaumann

AVIATION...Wise

HYDROLOGY...Grout