804
FOUS30 KWBC 091559
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1159 AM EDT THU APR 9 2026
DAY 1
VALID 16Z THU APR 09 2026 - 12Z FRI APR 10 2026
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PARTS OF THE
CENTRAL PLAINS, LOWER MISSOURI AND MID-MISSISSIPPI VALLEYS AND
ALONG THE EAST COAST OF FLORIDA...
..CENTRAL PLAINS TO MID-MISSISSIPPI VALLEY
16Z UPDATE: THE FORECAST REMAINS ON TRACK FOR A MARGINAL RISK FOR
EXCESSIVE RAINFALL AS MODEST MOISTURE RETURN FROM THE SOUTH AND AN
INCREASE IN INSTABILITY THROUGH THE DAY WILL INTERACT WITH A
STATIONARY FRONT ALIGNED FROM NORTHERN KANSAS EASTWARD TO ILLINOIS.
A DUAL QPF MAXIMA OF 1-2 INCHES IS FORECAST ALONG AND TO THE NORTH
OF A FRONT ACROSS THE I80 CORRIDOR FROM IOWA TO NORTHERN ILLINOIS.
NORTHEAST KANSAS INTO MISSOURI WILL BE ANOTHER FOCAL POINT FOR
POSSIBLE HEAVIER RAINFALL RATES NEAR AND SOUTH OF THE FRONT AND QPF
TOTALS NEARING 1-3 INCHES.
..PREVIOUS DISCUSSION..
THE SURFACE FRONTAL BOUNDARY STRETCHING FROM THE CENTRAL PLAINS
INTO THE MID MISSISSIPPI VALLEY IS EXPECTED TO BE NEARLY STATIONARY
DAY 1, REMAINING ORIENTED IN A GENERAL WEST TO EAST DIRECTION. IN
THE WAKE OF THE STRONG HEIGHT FALLS MOVING NORTHEAST FROM THE UPPER
LAKES INTO SOUTHEAST CANADA, ADDITIONAL SHORTWAVE ENERGY EXPECTED
TO DIVE SOUTHEAST FROM THE NORTHERN PLAINS INTO THE UPPER MS
VALLEY. THESE HEIGHT FALLS WILL HELP STRENGTHEN THE LOW LEVEL SOUTH
SOUTHWESTERLY FLOW INTO THIS BOUNDARY, PUSH PW VALUES TO 1 TO 2+
STANDARD DEVIATIONS ABOVE THE MEAN AND ENHANCE UVVS IN THE ABOVE
AVERAGE PW AXIS IN THE VICINITY OF THE STATIONARY FRONT. THIS WILL
SUPPORT INCREASING CONVECTION LATE THURSDAY AFTERNOON INTO THE
EARLY HOURS OF FRIDAY IN THE VICINITY OF THIS BOUNDARY WITH LOCALLY
HEAVY RAINFALL TOTALS AND ISOLATED RUNOFF ISSUES. ONLY SOME MINOR
CHANGES MADE TO THE PREVIOUS MARGINAL RISK AREA, TRIMMING IT TO THE
NORTHWEST ACROSS NORTHERN IL, AND EXTENDING IT SLIGHTLY FARTHER
SOUTH INTO NORTHEAST KS TO MATCH THE LATEST MODEL QPF CONSENSUS.
THE MARGINAL RISK FITS WELL WITH WHERE THE LATEST HREF NEIGHBORHOOD
PROBABILITIES ARE HIGHEST FOR 1 AND 2"+ TOTALS DURING THE UPCOMING
DAY 1 PERIOD.
..EAST COAST OF FLORIDA
16Z UPDATE: THUNDERSTORMS THIS MORNING WERE MOVING ACROSS THE
SPACE COAST, THE TREASURE COAST, AND THE MIAMI METRO. RADAR
ANALYSIS SHOWED RAINFALL RATES OF AN INCH TO TWO INCHES PER HOUR
OVER SATURATED SOILS FROM PREVIOUS DAYS. SHOWERS AND STORMS WILL
CONTINUE AMID THE STRONG NORTHEASTERLY FLOW ALONG THE EAST COAST OF
FLORID AND THE MARGINAL RISK CONTINUES THIS AFTERNOON.
..PREVIOUS DISCUSSION..
THE STRONG LOW LEVEL EAST NORTHEASTERLY FLOW WILL CONTINUE FOR AT
LEAST THE BEGINNING OF THE DAY 1 PERIOD ALONG THE EAST COAST OF
FLORIDA. PW VALUES WILL REMAIN ABOVE AVERAGE DURING THE DAY ON
THURSDAY, BEFORE BEGINNING TO DECREASE AS THE LOW LEVEL ONSHORE
FLOW WEAKENS AFTER 0000 UTC FRIDAY. THERE WILL CONTINUE TO BE THE
THREAT OF LOCALLY HEAVY RAINS FROM SLOW MOVING TO NEARLY STATIONARY
RAIN BANDS IN THIS STRONG MOIST ONSHORE FLOW REGION. CONFIDENCE IS
NOT GREAT WITH PLACEMENT, LEADING TO LITTLE IN THE WAY OF CHANGES
WITH TO THE PREVIOUS BROAD MARGINAL RISK AREA ALONG THE EAST
CENTRAL TO SOUTHEAST FLORIDA COASTAL REGION, WITH THE GREATEST RISK
OF RUNOFF ISSUES IN MORE URBANIZED REGIONS.
..SOUTH-CENTRAL TEXAS
A SUB-MARGINAL RISK FOR EXCESSIVE RAINFALL IS POSSIBLE FROM THE
HILL COUNTRY WESTWARD TO THE RIO GRANDE. THE QPF FORECAST CALLS FOR
A GENERAL 1.0-2.0 INCHES ACROSS THE REGION TODAY AS ENOUGH
MOISTURE AND INSTABILITY WILL BE PRESENT FOR SCATTERED
THUNDERSTORMS. A DISTURBANCE MOVING ACROSS THE MEXICAN PLATEAU
COULD ENHANCE LOCALLY HEAVIER RAINFALL TOTALS ACROSS THE RIO
GRANDE, WITH SOME UNCERTAINTY IF THE STORMS CAN MAINTAIN ACROSS THE
U.S./MEXICO BORDER LATE THIS AFTERNOON INTO THE EVENING. DRY
ANTECEDENT CONDITIONS AND LOW SIGNALS FROM THE HREF NEIGHBORHOOD
PROBABILITIES EXCEEDING 2 INCHES PRECLUDES A MARGINAL RISK FOR
EXCESSIVE RAINFALL AS OF THIS FORECAST PACKAGE.
ORAVEC/WILDER
DAY 2
VALID 12Z FRI APR 10 2026 - 12Z SAT APR 11 2026
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL TO SOUTHERN PLAINS...
THE WEST TO EAST FRONT STRETCHING FROM THE CENTRAL PLAINS INTO THE
MID-MISSISSIPPI VALLEY DAY 1 WILL BEGIN TO PUSH SOUTHWARD LATE DAY
1 INTO EARLY DAY 2. THIS FRONT WILL THEN AGAIN BECOMING STATIONARY
DURING THE DAY ON FRIDAY, ORIENTED WEST TO EAST FROM THE CENTRAL
PLAINS, EAST INTO THE LOWER MO VALLEY AND MID-MISSISSIPPI VALLEY.
SIMILAR TO THE DAY 1 PERIOD, PW VALUES SHOULD INCREASE IN THE
VICINITY OF THIS FRONT IN RESPONSE TO STRENGTHENING SOUTHERLY LOW
LEVEL INFLOW. SHORTWAVE ENERGY PUSHING NORTHEASTWARD INTO THIS HIGH
PW AXIS IN THE VICINITY OF THIS FRONT WILL SUPPORT AREAS OF SLOW
MOVING CONVECTION ALONG THIS FRONT, LOCALLY HEAVY RAINS AND
ISOLATED RUNOFF ISSUES. THE PREVIOUS MARGINAL RISK AREA WAS PUSHED
SOUTHWARD BY APPROXIMATELY 50-75 MILES TO FIT THE LATEST MODEL QPF
CONSENSUS. THERE STILL IS SOME LATITUDINAL SPREAD WITH THE MAX QPF
AXIS, WITH THE MORE SOUTHERN SOLUTION FAVORED IN THE LATEST WPC
QPF.
ORAVEC
DAY 3
VALID 12Z SAT APR 11 2026 - 12Z SUN APR 12 2026
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHERN PLAINS...
AN AXIS OF MUCH ABOVE AVERAGE PW VALUES EXPECTED TO INCREASE IN
SIZE DAY 3 ACROSS THE SOUTHERN TO CENTRAL PLAINS, INTO THE UPPER
MS VALLEY IN A REGION OF STRENGTHENING SOUTH SOUTHWESTERLY TO
SOUTHWESTERLY LOW TO MID LEVEL FLOW. THERE IS THE LIKELIHOOD OF
NUMEROUS SHORTWAVES MOVING NORTHEASTWARD IN THIS MID LEVEL
SOUTHWESTERLY FLOW ACROSS THE MID SECTION OF THE NATION, SUPPORTING
INCREASING PRECIP CHANCES/COVERAGE ACROSS THIS REGION. THERE STILL
IS A LARGE SPREAD IN THE MODELS WITH RESPECT TO PLACEMENT OF MAX
QPF, LEADING TO LOW CONFIDENCE AT THE MOMENT FOR THE DAY 3 TIME
PERIOD. GIVEN THE MODEL SPREAD AND DRY ANTECEDENT SOIL MOISTURE AND
HIGH FFG VALUES, THE RISK AREA WAS MAINTAINED AT MARGINAL, WITH
THE POTENTIAL FOR UPGRADE TO SLIGHT IN SUBSEQUENT MODEL CYCLES IF
BETTER AGREEMENT WITH MAX QPF AXES OCCURS.
ORAVEC
DAY 1 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/94EPOINTS.TXT
DAY 2 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/98EPOINTS.TXT
DAY 3 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/99EPOINTS.TXT
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