Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 222345
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
645 PM CDT SUN MAR 22 2015

...UPDATED AVIATION DISCUSSION...

.SHORT TERM /TONIGHT/...
ISSUED AT 333 PM CDT SUN MAR 22 2015

LOW PRESSURE OVER NORTHWEST KANSAS EXTENDS AN INVERTED TROUGH
NORTHEAST INTO EASTERN SOUTH DAKOTA. LOW WILL CONTINUE SOUTHEAST
TONIGHT WITH INVERTED TROUGH WEAKENING WITH TIME. MODELS SHOW
STRONG FORCING INT HE 850 TO 800 MB LAYER. BEST SUPPORT WILL BE
THIS EVENING TO THE NORTHEAST OF THE CWA. SOME INSTABILITY
ASSOCIATED WITH THIS SYSTEM. THIS CAN BE SEEN IN THE RADAR JUST
WEST OF THE COLD FRONT. NMM MODELS AVE A PRETTY GOOD HANDLE ON
THIS AND WILL GO WITH THAT TIMING FOR THE PRECIP OUTSIDE OF THE
BANDED ARE. AS FOR ACCUMULATION...FEEL ACCUMULATION WILL BE
LIMITED TO MY FAR NORTHEAST PART OF THE CWA AND UNDER AN INCH.

.LONG TERM /MONDAY THROUGH SUNDAY/...
ISSUED AT 333 PM CDT SUN MAR 22 2015

SOME LIGHT LINGERING PRECIPITATION FROM THE SYSTEM CURRENTLY
PUSHING THROUGH THE CWA SHOULD JUST BE EXITING THE CWA EARLY
MONDAY...WITH HIGH PRESSURE BUILDING INTO THE CWA BRIEFLY. MODELS
INDICATE LOW LEVEL STRATUS REMAINING ACROSS MUCH OF THE CWA
MONDAY...WITH SOME OF THE CLOUD DECK ERODING ACROSS THE FAR
WEST/NORTHWEST THROUGH THE DAY. ANY BREAKS IN THE CLOUDS ARE
QUICKLY FILLED IN WITH CLOUDS MOVING IN AHEAD OF THE NEXT SYSTEM
FOR LATE MONDAY NIGHT INTO TUESDAY NIGHT. NAM MOST BULLISH WITH
THIS NEXT SYSTEM...AND APPEARS TO BE OVERDONE AND TOO PROGRESSIVE
AND OVERALL AN OUTLIER. WITH IT TRYING TO MOVE PRECIPITATION IN
FASTER...SUGGESTS INITIAL PRECIP WOULD FALL AS FREEZING RAIN OR
MIX WITH SNOW. GIVEN THE AMOUNT OF DRY AIR TO INITIALLY OVERCOME
AND EASTERLY SURFACE FLOW...HISTORICAL TRENDS WITH THIS TYPE OF
SYSTEM SUGGESTS A LATER ONSET OF PRECIP SO TRENDED TOWARD THE SLOW
SOLUTIONS WHICH KEEPS THE MAJORITY OF PRECIP LINING UP WITH THE
WARMER AIR MOVING IN ALOFT WHICH SHOULD KEEP ALL THE PRECIP RAIN
WITH SFC TEMPS WARMING ABOVE FREEZING PRIOR TO THE PRECIP ONSET.
TRACK OF THE SURFACE LOW IS A BIT FURTHER SOUTH ALONG WITH THE
PLACEMENT OF THE UPPER LOW...THEREFORE AMOUNT OF WARMING IS
TEMPERED SOME AND ELEVATED INSTABILITY IS LIMITED. HAVE THUS
REMOVED MUCH OF THE THUNDER WORDING ACROSS THE CWA...CONFINING IT
TO MAINLY TUESDAY AFTERNOON INTO TUESDAY EVENING ACROSS THE FAR
SOUTH WHEN LAPSE RATES LOOK STEEPER THE WARM FRONT ALOFT MOVES
INTO THE AREA.

OVERALL EXPECT A BAND/AREA OF RAIN SHOWERS TO SPREAD NORTH ACROSS
THE SOUTHERN CWA LATE MONDAY NIGHT...AND MOVE NORTH/NORTHEASTWARD
THROUGH CENTRAL AND NORTHERN PORTIONS OF THE CWA TUESDAY MORNING.
THESE TYPES OF SCENARIOS MODELS TEND TO OVERDO THE DURATION OF
PRECIPITATION SO DO EXPECT A DRY PERIOD AFTER THE INITIAL AREA OF
WAA PRECIP PUSHES THROUGH BEFORE PRECIP REDEVELOPMENT EXPECTED
IN VICINITY OF THE INVERTED SFC TROUGH EXPECTED TO SWING THROUGH
THE SOUTHERN CWA TUESDAY AFTERNOON. WRAP-AROUND PRECIP ON THE
BACKSIDE OF THE SYSTEM EXPECTED TO SWING THROUGH THE CENTRAL/NORTH
TUESDAY AFTERNOON INTO TUESDAY NIGHT AS THE UPPER SYSTEM LIFTS
INTO THE GREAT LAKES BY EARLY WEDNESDAY. THERMAL PROFILES SUGGEST
SOME SNOW COLD MIX IN WITH THE RAIN TUESDAY NIGHT ACROSS THE FAR
NORTH...WITH BETTER CHANCES FOR WINTRY PRECIP INTO MINNESOTA.
SECONDARY SYSTEM STILL EXPECTED TO DIG INTO THE BACKSIDE OF THIS
WAVE WEDNESDAY INTO THURSDAY...SHOULD KEEP OVERALL CLOUDINESS
ACROSS THE REGION WITH ANY PRECIP REMAINING JUST TO THE NORTH/EAST
OF THE CWA.

MUCH COLDER AIR TO SINK INTO THE STATE BEHIND THIS SYSTEM INTO
FRIDAY...WITH A LARGE 1036 MB ARCTIC HIGH BUILDING IN WITH H85 TEMPS
DROPPING INTO THE -15C RANGE BY THE END OF THE WEEK. THIS WILL ALLOW
FOR CHILLY CONDITIONS TO RETURN TO THE CWA BY FRIDAY...WITH UPPER
LEVEL RIDGING BUILDING BACK IN FOR THE WEEKEND AND TEMPS WARMING
BACK TOWARD THE SEASONAL AVERAGES OF ABOVE BY THE END OF THE
UPCOMING WEEKEND. QPF AMOUNTS FOR THE EARLY WEEK SYSTEM SHOULD BRING
A WIDESPREAD HALF INCH TO THREE-QUARTERS OF AN INCH OF RAIN...AND
POSSIBLY AS MUCH AS AN INCH OF RAIN OR MORE IN LOCATIONS THAT MAY
SEE AN ISOLATED THUNDERSTORM.

&&

.AVIATION...23/00Z
ISSUED AT 637 PM CDT SUN MAR 22 2015

DELAYED THE ONSET OF PRECIP SLIGHTLY ACROSS THE NORTH AS THE
LATEST HRRR/HOPWRF HAVE IT MOVING IN PAST 03Z ONLY LEFT MVFR/IFR
CONDITIONS AT ALO/MCW. LOWER CONFIDENCE WITH A LONG DURATION
PRECIP AND STOPPED PRECIP BY EARLY MORNING MONDAY. LEFT OUT
MENTION AT DSM/OTM AND AS WELL AS FOD WITH STILL QUITE A LOT OF
DRY AIR IN PLACE. MVFR CIGS LOOK TO PERSIST THROUGH MUCH OF THE
DAY MONDAY.

&&

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

&&

$$

SHORT TERM...MS
LONG TERM...BEERENDS
AVIATION...PODRAZIK


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