Area Forecast Discussion
Issued by NWS Des Moines, IA

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000
FXUS63 KDMX 092036
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
336 PM CDT WED JUL 9 2014

.SHORT TERM /TONIGHT/...
ISSUED AT 335 PM CDT WED JUL 9 2014

QUIET WEATHER IS EXPECTED TO CONTINUE OVERNIGHT AS SURFACE RIDGING
SLIDES ACROSS THE AREA AND EAST INTO THE GREAT LAKES AREA BY
MORNING.  INITIALLY...WILL SEE SMOKE PLUME FROM CANADIAN FIRES
CONTINUE TO MOVE OVERHEAD INTO TONIGHT WHICH MAY PROVIDE A COLORFUL
SUNSET. IN ADDITION...SOME HAZY CONDITIONS MAY BE POSSIBLE OVERNIGHT
AS PARTICULATE MATTER INCREASES IN THE LOW LEVELS.  OTHERWISE...THE
SMOKE SHOULD HAVE LITTLE INFLUENCE ON OVERNIGHT TEMPERATURES WITH
READINGS FALLING BELOW NORMAL ONCE AGAIN WITH LIGHT WINDS REMAINING
AND RELATIVELY CLEAR SKIES.

.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
ISSUED AT 335 PM CDT WED JUL 9 2014

MAIN FORECAST CONCERN WAS FOCUSED ON SYSTEM THURSDAY NIGHT INTO
FRIDAY...SECONDARY SYSTEM ON SATURDAY...AND THEN WITH THE COOL
DOWN NEXT WEEK. LEANED TOWARD A NAM12/SREF BLEND THURSDAY INTO
FRIDAY...THEN SLIGHTLY MORE TOWARDS THE ECMWF OVER THE WEEKEND
INTO NEXT WEEK.

THURSDAY AND FRIDAY...SURFACE RIDGE SHIFTS EAST AND ALLOWS RETURN
FLOW TO DEVELOP THROUGHOUT THE DAY THURSDAY. MOISTURE TRANSPORT
AND THETA-E ADVECTION INCREASE ACROSS WESTERN IOWA BY 00Z FRIDAY
AND SPREADS SLOWLY EAST DURING THE EVENING THURSDAY. CUT BACK ON
TIMING OF POPS EAST OF I-35 FROM 00-06Z FRIDAY AND EVEN COULD GO
COMPLETELY DRY ACROSS THE EAST AS THE DEEPER FORCING LOOKS TO MOVE
THROUGH OVERNIGHT INTO FRIDAY MORNING. CONTINUED WITH THE HIGHEST
POPS FROM 06-12Z FRIDAY AS THE STRONGEST FORCING AND BEST MOISTURE
MOVE ACROSS THE FORECAST AREA DURING THIS TIME FRAME. HAVE SOME
LINGERING LIKELY POPS EAST OF I-35 FRIDAY MORNING DUE TO THE
MODELS TRENDING SLOWER WITH THIS SYSTEM.

SATURDAY THROUGH MONDAY...BOUNDARY SETS UP ACROSS IOWA FROM WEST TO
EAST FRIDAY NIGHT INTO SATURDAY WITH THE ASSOCIATED SURFACE LOW
DEVELOPING OVER THE WESTERN PLAINS. A FEW SMALL VORT MAXES TRACK
ACROSS THE STATE FRIDAY NIGHT THROUGH SUNDAY MORNING AND TIMING
THESE WILL BE DIFFICULT. HOWEVER...BOTH THE GFS AND ECMWF WANT TO
BRING IN A DECENT AMOUNT OF PRECIPITATION OVER THE WEEKEND...WITH
THE FIRST ROUND LATE FRIDAY NIGHT INTO SATURDAY MORNING AND THE
NEXT SATURDAY NIGHT INTO SUNDAY...COINCIDING WHEN THE LLJ
STRENGTHENS. TWEAKED UP QPF/POPS DURING THE AFOREMENTIONED TIME.
SEVERE POTENTIAL LOOKS LIMITED WITH MINIMAL INSTABILITY AND SHEAR
PRESENT WITH THIS SYSTEM OVER THE WEEKEND. HEAVY RAIN IS MORE
LIKELY THE GREATER THREAT WITH PRECIPITABLE WATER VALUES REACHING
2 INCHES AND THE WARM LAYER CLOUD DEPTHS TOPPING 13KFT TO 14KFT BY
SATURDAY. WEAK CORFIDI VECTORS AND STRONG MOISTURE TRANSPORT AND
DECENT CONVERGENCE ACROSS STATE ON LATE FRIDAY NIGHT INTO
SATURDAY. NO MENTION OF HEAVY RAIN ATTM DUE TO UNCERTAINTY OF
WHERE THE BOUNDARY LOCATION AND TIMING OF SHORTWAVE ON SATURDAY.

ANOTHER SHOT OF COOL CANADIAN AIR WILL FILTER INTO THE REGION BY
MONDAY AS A LARGE UPPER TROUGH MOVES INTO THE CENTRAL U.S. GFS IS
SLIGHTLY STRONGER WITH THE 500MB LOW...BUT THE EXTENDED MODELS ARE
IN FAIR AGREEMENT WITH TIMING AND LOCATION OF THE LOW. COOLED
TEMPS DOWN A LITTLE ON TUESDAY.

&&

.AVIATION...09/18Z
ISSUED AT 1241 PM CDT WED JUL 9 2014

RELATIVELY QUIET AVIATION WEATHER FOR THE DURATION OF THE FORECAST
PERIOD. MAIN CONCERN IS SMOKE DRIFTING SOUTHEAST TOWARD THE
STATE FROM CANADIAN WILDFIRES. THIS MAY PRODUCE SOME REDUCTION IN
VISIBILITY THIS EVENING INTO THE OVERNIGHT AND HAVE PUT IN SOME
HAZE FOR THE POTENTIAL. OTHERWISE...CEILINGS WILL REMAIN VFR WITH
LIGHT AND VARIABLE WINDS THROUGH TONIGHT BECOMING SOUTHEAST ON
THURSDAY.


&&

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

&&

$$

SHORT TERM...COGIL
LONG TERM...PODRAZIK
AVIATION...COGIL



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