Area Forecast Discussion
Issued by NWS Des Moines, IA

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KDMX 012340
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
640 PM CDT MON JUN 1 2015

.SHORT TERM /TONIGHT/...
ISSUED AT 326 PM CDT MON JUN 1 2015

HIGH PRESSURE REMAINS TO THE EAST WITH SOUTHEASTERLY FLOW ALOFT.
MOISTURE WRAPPING AROUND THE BASE OF THE HIGH CURRENTLY
RESPONSIBLE FOR A CU FIELD AND CLOUD DECK ACROSS SE IA/MO. AS
WINDS BECOME MORE SOUTHEASTERLY...THIS MOISTURE TO ADVECT INTO
CENTRAL PORTIONS OF THE CWA THROUGH THE EVENING AND INTO THE
EASTERN CWA LATE TONIGHT. WITH WAA AS WELL...COULD SEE A LOW/MID
LEVEL CLOUD DECK TO DEVELOP ACROSS MUCH OF THE CWA OVERNIGHT.
THEREFORE HAVE INCREASED CLOUD COVER FOR LATE EVENING/OVERNIGHT
AND KEPT HIGHS A BIT WARMER BENEATH THE POSSIBLE CLOUD COVER.
OTHERWISE WINDS TO REMAIN MORE SOUTHEASTERLY THROUGH THE PERIOD AT
THE SURFACE AS WELL.

.LONG TERM /TUESDAY THROUGH MONDAY/...
ISSUED AT 326 PM CDT MON JUN 1 2015

A SYNOPTIC BLOCKING PATTERN WILL BEGIN TO MATERIALIZE OVER THE
SOUTHEASTERN UNITED STATES ON TUESDAY MORNING AS THE CURRENT UPPER
LEVEL LOW OVER THE MID MISSISSIPPI RIVER VALLEY CUTS OFF FROM THE
NORTHERN STREAM AND MEANDERS OVER THE CENTRAL APPALACHIANS THROUGH
FRIDAY. RIDGING UPSTREAM OVER THE SOUTHERN PLAINS WILL EXTEND
NORTHWARD OVER IOWA AT THE ONSET OF THE PERIOD ON TUESDAY. SURFACE
HIGH WILL SHIFT EAST DURING THE DAY AND ALLOW THE HIGH PLAINS
THERMAL RIDGE/WAA TO PROGRESS FURTHER EAST INTO THE
CWA...ESPECIALLY AFTER 18Z AS 850MB TEMPS RISE FROM +10 TO +13 C
DURING THE AFTERNOON.

SOUNDINGS SHOW MANY LOCATIONS IN THE SOUTH CENTRAL AND SOUTHWEST
CWA REACHING THEIR CONVECTIVE TEMPS BY MID MORNING. HAVE INCREASED
SKY COVER THROUGH THE EARLY TO MID AFTERNOON HOURS...WITH THE
EXPECTATION THAT THE WARMING PROFILES AND MIXING OF DRY AIR JUST
ABOVE CLOUDS WILL LEAD TO THE DISSIPATION OF THIS CU FIELD BY THE
MID AFTERNOON FROM WEST TO EAST. HAVE ALSO CAUTIOUSLY NUDGED DOWN
HIGHS IN THE SOUTHWEST BY A DEGREE OR SO...WHICH WILL DEPEND
HEAVILY ON HOW QUICKLY THE CLOUDS CLEAR OUT.

ATTENTION THEN TURNS TO THE LATTER...MORE ACTIVE PORTION OF THE
WEEK. CURRENT AMPLIFIED SHORTWAVE WRAPPING AROUND THE EASTERN FLANK
OF A NORTHWEST PACIFIC COAST LOW WILL BREAK OFF AND EJECT
NORTHEASTWARD ACROSS THE DAKOTAS LATE IN THE DAY TUESDAY. THIS WILL
HELP FLATTEN THE SYNOPTIC RIDGE AND PLACE IOWA IN A BROAD WSW FLOW.
MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
STARTING EARLY WEDNESDAY MORNING IN NORTHWEST IOWA...AND SPREADING
ACROSS ALL OF CENTRAL IOWA FOR WEDNESDAY THROUGH FRIDAY AFTERNOON AS
A SURFACE FRONTAL BOUNDARY LINGERS NEAR THE STATE. HAIL AND HEAVY
RAIN APPEAR TO BE THE PRIMARY THREATS GIVEN MUCAPE VALUES OF 1200
J/KG WEDNESDAY MORNING AND SBCAPE VALUES OF OVER 2000 J/KG ON
WEDNESDAY THROUGH FRIDAY AFTERNOONS IN CONJUNCTION WITH PERSISTENT
PWAT VALUES OF 1.5 THROUGH 1.7 INCHES. WEAK SHEAR PROFILES WILL
LIMIT STORM ORGANIZATION AND MODE. CONFIDENCE IS HIGH IN THERE
BEING CONVECTION DURING THIS TIMEFRAME...BUT TIMING AND LOCATION
ARE MORE UNCERTAIN GIVEN THE WEAK FLOW.

THE SURFACE COLD FRONT WILL SLIDE OUT OF THE STATE ON FRIDAY EVENING
AS THE BLOCKING PATTERN BREAKS DOWN OUT EAST. SATURDAY WILL FEATURE
SLIGHTLY COOLER AND DRIER WEATHER WITH EASTERLY FLOW OFF A GREAT
LAKES HIGH...FOLLOWED BY RETURN SOUTHERLY FLOW AND STORMS FOR
SUNDAY. THE BEGINNING OF NEXT WEEK LOOKS DRY AND SEASONABLE WITH
PREDOMINANTLY WEST TO NORTHWEST FLOW.

&&

.AVIATION...02/00Z
ISSUED AT 639 PM CDT MON JUN 1 2015

DRY AIRMASS ACROSS CENTRAL IOWA WILL BEGIN TO BE REPLACED BY
MOISTURE FROM THE SOUTHEAST OVERNIGHT. THIS WILL LEAD TO THE
DEVELOPMENT OF STATUS LATE TONIGHT IN PORTIONS OF THE AREA WITH
MVFR TO IFR CEILINGS TOWARD DAYBREAK ON TUESDAY. THIS LOW STATUS
WILL LIKELY GIVE WAY TO VFR CEILINGS BY MID TO LATE MORNING AS
SOUTHEAST SURFACE WINDS INCREASE.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...BEERENDS
LONG TERM...SKOW
AVIATION...COGIL


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.