Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 192056
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
356 PM CDT TUE MAY 19 2015

.SHORT TERM /TONIGHT/...
ISSUED AT 356 PM CDT TUE MAY 19 2015

WAVE ASSOCIATED WITH SURFACE LOW CURRENTLY IN COLORADO WILL CONTINUE
TO PUSH EASTWARD THROUGHOUT THE EVENING AND OVERNIGHT
HOURS...PUSHING ONGOING PRECIPITATION ACROSS CENTRAL KS/NE EASTWARD.
MAIN CONCERN WILL BE TIMING OF ONSET OF PRECIPITATION AND NORTHWARD
EXTENT. MODELS ARE CONSISTENT WITH KEEPING BEST FORCING AND MOISTURE
INTO NORTHERN MISSOURI/SOUTHERN IOWA...HOWEVER ISENTROPIC ANALYSIS
AND SOUNDINGS INDICATES MOISTURE CONTINUING TO PUSH INTO CENTRAL
IOWA AND HAVE ONLY CUT BACK SLIGHTLY ON NORTHERN EXTENT OF
PRECIPITATION. HIGH RES MODELS ARE CONSISTENT WITH BRINGING WAVE OF
PRECIPITATION INTO SOUTHERN IOWA NEAR 00Z...THOUGH HAVE FOUND LITTLE
SUPPORT FOR THIS AND HAVE KEPT MENTION OUT FOR NOW...BRINGING
PRECIPITATION IN LATER WHEN BEST THETA-E ADVECTION ARRIVES CLOSER TO
06Z...WHICH IS SLIGHTLY SLOWER THAN PREVIOUS FORECAST. HAVE KEPT
TEMPERATURES NEAR GOING...THOUGH HAVE BUMPED DOWN A DEGREE OR
TWO...ESPECIALLY IN THE NORTH WHERE WINDS WILL BE LIGHT...THOUGH
CLOUD COVER MAY HELP TO LIMIT COOLING SOMEWHAT.

.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
ISSUED AT 356 PM CDT TUE MAY 19 2015

THE PRECIPITATION FROM THE OVERNIGHT IS EXPECTED TO BE WIDESPREAD
OVER CENTRAL AND SOUTH CENTRAL IOWA WEDNESDAY MORNING. HIGH
PRESSURE SITUATED OVER THE NORTHERN PLAINS WILL KEEP DRIER AIR
OVER THE NORTHERN PORTION OF THE STATE AND WILL LIMIT
PRECIPITATION CHANCES OVER THAT PORTION OF THE AREA. THE PRIMARY
KINEMATIC FORCING WILL BE BETWEEN 12-18Z WITH THIS PERIOD
REPRESENTING THE BEST POTENTIAL FOR PRECIPITATION. DRIER AIR WILL
BEGIN TO ADVECT IN FROM WEST TO EAST FROM LATE MORNING AND THROUGH
THE AFTERNOON WITH MOISTURE DEPTHS DECREASING. POSSIBLE THE
RAIN/SHOWERS WILL DIMINISH TO A PERIOD OF DRIZZLE BEFORE ENDING.
THE BULK OF CONVECTIVE INSTABILITY IS EXPECTED TO REMAINS JUST
SOUTH OF IOWA INTO NORTHERN MISSOURI THOUGH SOME MINOR MUCAPES UP
TO 100 J/KG REACH INTO THE FAR SOUTH...HAVE KEPT THUNDER OUT AT
THIS POINT. COOLING ALOFT WILL RESULT IN 850 MB TEMPERATURES
DROPPING BACK TO NEAR 0C ON WEDNESDAY. THIS FACTORED IN WITH THE
CLOUD COVER WILL LEAD TO TEMPERATURES IN THE 40S MUCH OF THE DAY
WHERE RAIN IS OCCURRING. VERY PESSIMISTIC ABOUT READINGS
REBOUNDING INTO THE 50S ONCE THE RAIN ENDS. AT THIS POINT HAVE
SETTLED WITH HIGHS IN THE LOWER 50S CENTRAL AND SOUTH AND MID 50S
NORTH.

HIGH PRESSURE WILL SETTLE INTO THE AREA THURSDAY AND FRIDAY WITH
DRY CONDITIONS AND WARMER BUT STILL SEASONABLY COOL READINGS
THURSDAY WITH HIGHS IN THE 60S THE 60S AND 70S AND ON FRIDAY. THE
NEXT UPPER LOW WILL MOVE INTO THE DESERT SOUTHWEST THURSDAY NIGHT
AND FRIDAY THEN WILL PROGRESS NORTHEAST INTO THE INTERMOUNTAIN
WEST AND LEADING TO INCREASED SOUTHWEST FLOW ALOFT. THE SOUTHWEST
FLOW AND INCREASING LOW LEVEL FLOW ORIGINATING FROM THE GULF WILL
BRING INCREASED THUNDERSTORM CHANCES TO THE STATE FOR THE MEMORIAL
DAY WEEKEND. OVERALL NOT A SIGNIFICANT SEVERE WEATHER THREAT
THROUGH THE PERIOD. SHEAR PROFILES SUPPORT MULTICELLULAR STORMS
WITH MARGINAL SUPERCELL POTENTIAL AT TIMES. THE BEST INSTABILITY
WILL BE SUNDAY AND MONDAY HOWEVER PROFILES THROUGH THIS PERIOD
BECOME QUITE SATURATED WITH PWAT VALUES NEARING 1.75 INCHES. WILL
CERTAINLY NEED TO MONITOR FOR HEAVY RAIN POTENTIAL.

&&

.AVIATION...19/18Z
ISSUED AT 1234 PM CDT TUE MAY 19 2015

MVFR CEILINGS WILL CONTINUE TO LIFT AT SITES THROUGH THE BEGINNING
OF THE PERIOD WITH SITES TO VFR BY 20Z. WINDS WILL REMAIN FROM
THE NORTH TO NORTHEAST AND WILL DIMINISH AFTER 00Z. RA WILL BEGIN
TO PUSH INTO SITES FROM WEST TO EAST AFTER 06Z...WITH BEST CHANCES
AT KFOD/KDSM/KOTM NEAR 12Z. WITH RA WILL SEE MVFR OR LOWER
CEILINGS AND VISIBILITIES AND HAVE TRENDED THIS WAY FOR NOW.


&&

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

$$

SHORT TERM...AWB
LONG TERM...DONAVON
AVIATION...AWB


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