Soggy Sunday in Mobile, AL
It was a VERY wet day along the Gulf Coast on Sunday. Get this, Mobile, AL saw 7.28″ of rain; shattering the previous record of 3.61″ set in 1980. Not only was it a daily rainfall record for Mobile, AL, but it was also the 4th wettest April day in recorded history!
Flash Flood Watch
* THROUGH TUESDAY EVENING
* SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH
TUESDAY EVENING…AND AREAS OF HEAVY RAINFALL ARE EXPECTED.
ADDITIONAL RAINFALL AMOUNTS OF 3 TO 5 INCHES WILL BE POSSIBLE.
MANY AREAS OF SOUTHEAST LOUISIANA AND ACROSS THE MISSISSIPPI
COAST ALONG AND SOUTH OF THE INTERSTATE 10 12 CORRIDOR HAVE
SATURATED SOILS FROM RECENT HEAVY RAINFALL…AND ADDITIONAL
HEAVY RAINFALL MAY QUICKLY RUNOFF RESULTING IN FLASH FLOODING OF
POORLY DRAINED…LOW LYING AREAS.
* AREAS THAT SEE CONTINUOUS TRAINING OF HEAVY RAINFALL WITHIN A
SHORT TIME COULD RECEIVE FLOOD WATER TO DEPTHS THAT WOULD
IMPACT PROPERTY AND PEOPLE IN THOSE AREAS. AREA CREEKS…
STREAMS AND RIVERS ARE ALSO LIKELY TO EXPERIENCE RISES…AND
SOME MAY RISE TO BANKFULL OR FLOOD LEVELS OVER THE NEXT
National Weather Outlook
A fairly weak upper level disturbance will keep the rain/thunder threat ongoing across the Gulf Coast States through midweek. Heavy rainfall and a few strong storms can’t be ruled out. Another disturbance will begin to feed into the Rockies through the first half of the week with snow accumulations across the high elevations.
Severe Threat Monday
…TX THIS AFTERNOON/EVENING…
AN OVERALL WEAKENING TREND TO THE DEEP-LAYER CYCLONE IS FORECAST
TODAY AS IT DRIFTS EWD. HOWEVER…BREAKS IN THE CLOUDS WITHIN THE
MID-LEVEL DRY SLOT PRECEDING THE UPPER CIRCULATION CENTER COUPLED
WITH BOUNDARY-LAYER DEWPOINTS IN THE 60S WILL CONTRIBUTE TO
CORRIDORS OF MODERATE AFTERNOON INSTABILITY WITH MLCAPE VALUES
APPROACHING 1000-2000 J/KG. LOW-LEVEL UPLIFT ALONG ACTIVE
CONVECTIVE OUTFLOWS AND THE COLD FRONT MAY BE AUGMENTED BY A
VORTICITY LOBE ROTATING AROUND THE PARENT UPPER-AIR CIRCULATION TO
FOSTER AN UPTICK IN STORM COVERAGE AND INTENSITY BY AFTERNOON FROM
PORTIONS OF THE PERMIAN BASIN AND BIG COUNTRY INTO NRN AND CNTRL TX.
DESPITE RELATIVELY WEAK LOW-LEVEL FLOW…FORECAST HODOGRAPHS EXHIBIT
VEERING AND STRENGTHENING WINDS WITH HEIGHT WITH SUFFICIENT VERTICAL
SHEAR TO SUPPORT SUPERCELL STORM MODES WITH A RISK FOR LARGE HAIL
AND LOCALLY DAMAGING WIND GUSTS. A BRIEF TORNADO IS
POSSIBLE…ESPECIALLY WITH ANY SUSTAINED STORMS NEAR AND EAST OF THE
SURFACE TRIPLE POINT WHERE LOW-LEVEL SHEAR IS ENHANCED.
…CNTRL GULF COAST TODAY…
A LONG-LIVED QLCS AND ASSOCIATED MCV ARE PRESENT AS OF 12Z FROM THE
SABINE RIVER VALLEY SWD INTO THE NWRN GULF OF MEXICO WITH AN
OBSERVED SYSTEM MOTION OF 240/30-35 KT. PROXIMITY SOUNDINGS AT LCH
AND LIX SAMPLED A VERY MOIST AIR MASS WITH PW VALUES OF AROUND 1.9
INCHES AND LOWEST-100-MB MEAN-MIXING RATIOS OF 15-16 G/KG. WHILE
WIDESPREAD CLOUDS WILL LIMIT DAYTIME HEATING…THE COMBINATION OF
THE MOIST AIR MASS AND ENHANCEMENTS TO VERTICAL SHEAR AND FORCING
FOR ASCENT ON THE MESOSCALE SHOULD SUPPORT THE CONTINUATION OF THE
QLCS ACROSS THE MARGINAL RISK. WHILE ISOLATED STRONG WIND GUSTS
WILL BE THE PRIMARY HAZARD…A BRIEF TORNADO CANNOT BE RULED OUT.
…UPPER OH VALLEY/LOWER GREAT LAKES THIS AFTERNOON…
BOTH FORCING FOR ASCENT AND WSWLY DEEP-LAYER FLOW WILL INCREASE
TODAY AHEAD OF THE SHORT-WAVE TROUGH MOVING THROUGH THE REGION WITH
A BROKEN BAND OF TSTMS FORMING ALONG THE COLD FRONT BY AFTERNOON.
GENERALLY WEAK MID-LEVEL LAPSE RATES AND MARGINAL BOUNDARY-LAYER
MOISTURE CONTENT SHOULD LIMIT THE DEGREE OF AIR MASS DESTABILIZATION
AND RELATED POTENTIAL FOR HIGHER-ORDER STORM MODES.
NONETHELESS…LOCALLY STRONG WIND GUSTS MAY OCCUR WITH THE PASSAGE
OF THIS LINE OF STORMS.
Severe Threat Wednesday
…CNTRL AND SRN HIGH PLAINS…
STRONG HEATING WILL OCCUR DURING THE DAY WITH SURFACE CONVERGENCE
INCREASING DUE TO THE DEEPENING LOW. WEAK INSTABILITY WILL DEVELOP
LATE IN THE DAY COINCIDENT WITH THE ARRIVAL OF AN INCREASINGLY MOIST
AIR MASS AS SURFACE WINDS BACK. LAPSE RATES ALOFT WILL BE
STEEP…AND ISOLATED STORMS CAPABLE OF LARGE HAIL APPEAR LIKELY FROM
ERN CO INTO FAR WRN KS…ERN NM AND WRN TX. THE STRONGLY BACKED
LOW-LEVEL WINDS MAY SUPPORT A BRIEF/ISOLATED TORNADO INTO ERN CO. TO
THE S…STORMS OVER SWRN TX MAY PERSIST INTO THE OVERNIGHT PERIOD
WITH MARGINAL HAIL/WIND WITH ACCESS TO BETTER MOISTURE.
Heavy Rainfall Forecast
According to NOAA’s HPC, the 5 day rainfall forecast shows nearly 3″ to 5″+ possible through AM Saturday. Keep in mind that these are areas that have have seen quite a bit of precipitation over the past 30 days already!
Precipitation Past 30 Days
The graphic below shows how much precipitation we’ve seen over the past 30 days. Note the near 10″ to 20″ from parts of the Lower Mississippi Valley to the Ohio Valley!
(Image courtesy: WeatherBell)
Precipitation Percent of Normal
Interestingly, the swath of heavy precipitation above is any were from 110% to nearly 200%+ above average precipitation over the last 30 days. Also note that the Southwest over the last 30 days has been quite dry!
Thanks for checking in and have a great rest of your week. Don’t forget to follow me on Twitter @TNelsonWX