000
FXUS63 KMPX 182012
AFDMPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
312 PM CDT SAT MAY 18 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013
THE HYDROLOGIC ISSUES FOR TONIGHT AND SUNDAY ARE DISCUSSED IN A
SEPARATE SECTION BELOW. CONVECTION IS EXPECTED TO DEVELOP LATE
THIS AFTERNOON ACROSS WEST CENTRAL MN AND PROPAGATE SLOWLY ENE
THROUGH THE EVENING. MORE CONVECTION IS FORECAST TO EXPLODE OVER
NE/KS AND RACE NE...PERHAPS REACHING SW MN AFTER MIDNIGHT AND INTO
CENTRAL...EAST CENTRAL AND SOUTHEAST MN DURING THE LATE NIGHT
HOURS. DEEP LAYER SHEAR IS BEST TONIGHT ACROSS WEST CENTRAL INTO
CENTRAL MN ALONG WITH ML CAPE NEAR 1500 J/KG. DOWNDRAFT CAPE IS
ALREADY NEAR A 1000 J/KG NEAR OUR WESTERN BORDER ATTM. HENCE...A
FEW SEVERE STORMS WITH HAIL AND WIND ARE POSSIBLE.
SUNDAY SHOULD BEGIN WITH CONVECTION ACROSS CENTRAL AND EASTERN MN
WHICH WILL WEAKEN/DISSIPATE WHILE MOVING NE THROUGH THE LATE
MORNING HOURS. THERE MAY BE A FEW HOURS DURING THE LATE MORNING
AND EARLY AFTERNOON WITH SOME SUNSHINE AND LITTLE CONVECTION
OCCURRING. THAT IS LIKELY TO CHANGE DURING THE MID TO LATE
AFTERNOON HOURS WITH CLUSTERS OF STRONG TO SEVERE STORMS
DEVELOPING ACROSS CENTRAL AND SOUTHERN MN AND BY EVENING ACROSS
WEST CENTRAL WI. MODEL CONSENSUS IS FOR 1500-2000 J/KG OF CAPE
WITH NEARLY 500 J/KG BEING HAIL CAPE. DEEP LAYER SHEAR IS BEST
(30-40 KNOTS) ACROSS SOUTHERN MN INTO WEST CENTRAL WI DURING THE
LATE AFTERNOON AND EVENING. HOWEVER...0-1KM SHEAR INCREASES TO
NEAR 25 KNOTS ACROSS CENTRAL MN WITH SFC-3KM CAPE OVER 150 J/KG
ALONG AND SOUTH OF THE AFOREMENTIONED BOUNDARY. THIS WILL NEED TO
BE WATCHED FOR POSSIBLE TORNADIC DEVELOPMENT.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013
THE LONG TERM FORECAST REMAINS QUITE WET INTO THURSDAY AS A
VERTICALLY STACKED LOW PRESSURE SYSTEM OVER THE NORTHERN AND
CENTRAL PLAINS BEGINS A SLOW EASTWARD DRIFT. THUNDERSTORMS WILL
WANE SUNDAY NIGHT WHILE MOVING NE. HOWEVER...MONDAY REMAINS A DAY
OF INTEREST FOR MORE SEVERE WEATHER OVER OUR EASTERN FA. AN
OCCLUDED FRONT WILL LIFT NORTHEAST ACROSS EASTERN MN AND WEST
CENTRAL WI DURING THE DAY. CAPE AND SHEAR VALUES ARE RESPECTABLE
BY AFTERNOON FROM THE TWIN CITIES ON EAST AND SOUTH AND A FEW MORE
SEVERE STORMS ARE POSSIBLE. THERE REMAINS A SMALL CHANCE FOR
THUNDER TUESDAY AND WEDNESDAY...DEPENDING ON HOW FAST THE
VERTICALLY STACKED LOW PRESSURE SYSTEM MOVES. RIGHT NOW...THERE
CONTINUES TO BE A SLOWING TREND. HENCE...WE WILL BE DEALING WITH
RATHER HIGH POPS THROUGH MID WEEK.
THE GFS AND EC SHOW THIS LOW PRESSURE SYSTEM BREAKING DOWN ACROSS
THE REGION ON THURSDAY WITH HIGH PRESSURE FOR FRIDAY AND PERHAPS
SATURDAY BEFORE YET ANOTHER LARGE UPPER TROUGH MOVES INTO THE
WESTERN THIRD OF THE NATION...SPREADING MORE SHOWERS BACK. THE
WARMEST DAY IN THE EXTENDED RANGE IS ON MONDAY WITH HIGHS IN THE
50S AND 60S FOR TUESDAY AND WEDNESDAY WITH 60S TO LOWER 70S FOR
FRIDAY AND SATURDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 107 PM CDT SAT MAY 18 2013
MORNING STORMS LEFT BEHIND AN AREA OF MVFR CIGS AND EVEN SOME IFR
VSBYS IN SPOTS FROM WEST CENTRAL MN INTO WISC. THIS WILL HANG ON
FOR ANOTHER HOUR OR TWO AT PLACES LIKE AXN/STC/RNH...WHICH ARE
FARTHER NORTH OF THE WARM FRONT CURRENTLY IN SOUTHERN MN. ANOTHER
ISSUE IS POTENTIAL FOR MVFR FOG TONIGHT IN EASTERN MN AND WISC
WITH RESIDUAL MOISTURE AND SOUTHEAST WINDS. THIRD ISSUE IS
DEVELOPMENT OF STORMS THIS EVENING IN WEST CENTRAL MN PER HOPWRF
AND OTHER SHORT TERM MODELS. NORTHEAST MOVEMENT TO INDIVIDUAL
STORMS BUT OVERALL AREA GRADUALLY TRANSLATES EASTWARD...REACHING
EASTERN MN AND WESTERN WISC 08Z-12Z.
KMSP...DRY WEATHER IN WAKE OF MORNING STORMS. NAM SUGGESTS
REDEVELOPING STORMS IN WESTERN MN REACHING KMSP SHORTLY AFTER 00Z
THIS EVENING BUT MOST SHORT TERM MODELS HOLD OFF UNTIL LATE
TONIGHT. THUS HAVE PRECIP AT KMSP NOT UNTIL 10Z. COULD WELL BE TWO
OR THREE HOURS OF THUNDER BUT HAVE NOT ADDED THAT WITH UNCERTAIN
TIMING. SOME GUSTS POSSIBLE AROUND 20 KTS THIS AFTERNOON PER KMPX
SOUNDING.
/OUTLOOK FOR KMSP/
SUN NIGHT...MVFR CIGS/VSBY. LIKELY SHRA/TSRA WITH CHC IFR. S-SE WINDS 8-12
KTS.
MON...VFR/MVFR CIGS. CHC SHRA/TSRA. S WIND 10-15 KTS.
TUE...VFR/MVFR CIGS. CHC SHRA/TSRA. E-NE WIND 5 KTS.
&&
.HYDROLOGY...
ISSUED AT 312 PM CDT SAT MAY 18 2013
A SIGNIFICANT RAINFALL EVENT IS POSSIBLE TONIGHT AND SUNDAY
MORNING ACROSS CENTRAL MN. PW VALUES ARE PROJECTED TO INCREASE TO
OVER 1.50 INCHES TONIGHT ACROSS THE MN FA IN CONCERT WITH A
DEVELOPING LOW LEVEL JET. THE PW VALUES FORECAST ARE BETTER THAN
2 STANDARD DEVIATIONS ABOVE NORMAL AND ARE NEAR RECORD VALUES FOR
THE MONTH OF MAY (1.67). A SPECIAL 16Z KMPX RAOB THIS MORNING ALREADY
HAD PW VALUES AT 1.38 INCHES. WITH THE INCREASE IN MOISTURE
TONIGHT... THERE IS STRONG (925-850MB) FRONTOGENESIS THAT DEVELOPS
ACROSS CENTRAL MN AND REMAINS IN PLACE THROUGH MIDDAY SUNDAY. IN
ADDITION...AN INVERTED SURFACE TROUGH ACROSS CENTRAL SD AND
EASTERN ND IS FORECAST TO DROP SE INTO CENTRAL AND NORTHERN MN
BY SUNDAY MORNING WITH PRETTY STRONG LOW LEVEL CONVERGENCE SHOWN.
VARIOUS WRF MODELS SHOW CONVECTION SPREADING/DEVELOPING ACROSS
CENTRAL MN THIS EVENING WITH TRAINING NOTED. ANOTHER ROUND OF
CONVECTION MAY MOVE IN LATE IN THE NIGHT FROM EASTERN SD AND SW
MN. THE STORMS COULD EASILY PRODUCE 1 TO 2 INCHES OF RAIN PER HOUR
AS THEY MOVE THROUGH...MUCH LIKE THE STORMS LAST NIGHT AND THIS
MORNING OVER PARTS OF THE MN FA. IN FACT...WIDESPREAD 1 TO 3 INCH
RAINS FELL ACROSS CENTRAL MN EARLY THIS MORNING...WHICH HAS
CERTAINLY SOAKED THE GROUND. HENCE...IN COLLABORATION WITH
KDLH...WE ISSUED A FLASH FLOOD WATCH FROM 9 PM THIS EVENING UNTIL
1 PM ON SUNDAY FOR AREAS ALONG AND NORTH OF A LINE FROM MORRIS
THROUGH ST. CLOUD TO CAMBRIDGE.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH FROM 9 PM CDT THIS EVENING THROUGH SUNDAY
AFTERNOON FOR MNZ041>045-047>052.
WI...NONE.
&&
$$
SHORT TERM...RAH
LONG TERM...RAH
AVIATION...TDK
HYDROLOGY...RAH
