Area Forecast Discussion
Issued by NWS Quad Cities, IA IL

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000
FXUS63 KDVN 202022
AFDDVN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
322 PM CDT SUN APR 20 2014

.SYNOPSIS...
ISSUED AT 320 PM CDT SUN APR 20 2014

LATEST SFC ANALYSIS WAS INDICATING A GENERAL WNW-TO-ESE ORIENTED
BOUNDARY DRAPED ACRS NORTHERN IA AND TO THE NORTHERN FRINGES OF THE
DVN CWA. DEEP DRY MIXING UNDER MOSTLY SUNNY SKIES HAVE ALLOWED THE
ENTIRE CWA TO WARM INTO THE UPPER 70S TO LOWER 80S...WITH HUMIDITY
LEVELS IN THE 30S AND 20S...A TASTE OF CALIFORNIA WX. SHOWERS AND
THUNDERSTORMS CONTINUE TO FESTER IN H85 MB TEMP AND H85-H7MB THTA-E
ADVECTION/CONVERGENT ZONE JUST TO THE NORTH OF THE DVN CWA...ALSO
AIDED BY WEAK VORT ALOFT ALONG THE IA/MN BORDER.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 320 PM CDT SUN APR 20 2014

TONIGHT...ELEVATED THTA-E ADVECTION AND CONVERGENT FIELDS ON
ACCEPTED MODEL PROGS SUPPORT MORE ELEVATED SHOWER AND SOME
THUNDERSTORM DEVELOPMENT ACRS SOUTHWESTERN IA INTO NORTH CENTRAL
AND NORTHEASTERN IA THIS EVENING...ALONG WITH LIFT OFF APPROACH OF
ANOTHER VORT OUT OF THE SOUTHERN PLAINS. BUT WITH ONGOING DRY SUB H7
MB LAYER LOCALLY...COULD SEE A SCENARIO WHERE MUCH OF THE DVN CWA
STAYS DRY THROUGH AT LEAST MIDNIGHT...EXCEPT MAYBE THE FAR NORTHWEST
AND NORTHERN CWA WHERE SOME DECAYING/WEAKENING ACTIVITY MAKES IT IN
FROM THE WEST. WILL ADJUST POPS ACCORDINGLY. THESE TRENDS MAY
PERSIST TO WELL AFTER MIDNIGHT UNTIL AN ELEVATED WARM AIR ADVECTION
WING WITH SOME MORE PUNCH CAN TRY AND DRIVE SOME SHOWERS ACRS THE
NORTHWESTERN HALF OF THE CWA TO THE MS RVR THROUGH 12Z MON.
SOUTHERLY BREEZE AND CLOUD DEBRIS SHOULD HOLD LOWS UP IN THE MID TO
UPPER 50S IN MOST OF THE CWA...BUT THINNER CLOUDS TO CLEAR/DRY AREAS
OF THE NORTHEAST MAY GET COOLER.

MONDAY...SOME PHASING IN SLUGGISH SPLIT FLOW PATTERN JUST UPSTREAM
OF THE AREA STILL ON TRACK TO USHER A FRONTAL SYSTEM THROUGH THE
AREA FROM WEST-TO-EAST WITH THIS FEATURE POSSIBLY STILL LINGERING
ACRS THE FAR EASTERN CWA BY 00Z TUE. LOW TO MID LEVEL MOISTURE
RETURN INTO THIS FEATURE ENOUGH TO FUEL WIDESPREAD SHOWERS STILL AT
QUESTION WITH MOST MODELS STILL PROBABLY OVERDOING LLVL MOISTURE/
SATURATION BY MIDDAY MONDAY. BUT EVEN UNDERCUTTING THOSE AMOUNTS
SOME AND LOOKING AT AMOUNT OF FORCING/LIFT PROGRESSING ACRS THE AREA
STILL SHOULD PRODUCE WIDESPREAD SCTRD SHOWERS ACRS THE CWA AS MONDAY
PROGRESSES/POSSIBLY NOT INTO THE EAST CENTRAL AND SOUTHEASTERN CWA
UNTIL AFTERNOON/. SOME CAPE/MUCAPE VALUES EVIDENT AS WELL TO FUEL
THUNDERSTORMS SOME OF WHICH MAY PRODUCE SMALL HAIL IN THE AFTERNOON.
BUT OVERALL SVR THREAT STILL APPEARS LIMITED FOR MONDAY. WILL SIDE
WITH A LITTLE BIT OF THE WARMER GUIDANCE VALUES IN CASE SHOWERS
HAVING TROUBLE GETTING GOING/DEEPER SATURATION HOLDS OFF UNTIL
AFTERNOON...LOW TO MID 70S. RIGHT NOW IT APPEARS BULK OF CWA TO GET
ANYWHERE FROM 0.25-0.40 INCHES OF RAIN BY LATE MON AFTERNOON...BUT
OF COURSE ANY LOCALIZED AREAS THAT MANAGE TO GET UNDER A DECENT
THUNDERSTORM OR HAVE A FEW STORMS MOVE OVER THE SAME LOCATION COULD
GET AT LEAST THREE QUARTERS OF AN INCH. ON THE OTHER HAND...COULD
SEE SOME AREAS MISSING OUT ESPECIALLY EAST OF THE MS RVR.   ..12..


.LONG TERM...(MONDAY NIGHT THROUGH NEXT SUNDAY)
ISSUED AT 320 PM CDT SUN APR 20 2014

WITH THE COLD FRONT WELL TO THE EAST BY EVENING...MONDAY NIGHT WILL
FEATURE MOSTLY CLEAR SKIES AND SEASONABLY COOL TEMPERATURES AS HIGH
PRESSURE BUILDS INTO THE REGION FROM THE NORTHERN PLAINS. WILL KEEP
TOKEN SLIGHT CHANCE POPS FOR SHOWERS EARLY IN THE EVENING OVER THE
FAR EAST TO ACCOUNT FOR POSSIBLE SLOWER FRONTAL TIMING. DRY AIR AND
NEAR FULL SUNSHINE TUESDAY WILL LEAD TO DEEP MIXING AND HAVE
REFLECTED THE MODEL TRENDS WITH WARMER HIGHS IN THE LOWER TO MID
60S. THESE HIGHS MAY STILL BE TOO CONSERVATIVE GIVEN THE POOR RECENT
VERIFICATION SHOWING A COOL BIAS WITH THESE DRY AIRMASSES.
LIKEWISE...DRY AIR WILL FAVOR LARGER THAN NORMAL DIURNAL SWINGS INTO
THE OVERNIGHT WITH LOWS IN THE MID 30S TO LOWER 40S TUESDAY NIGHT.

WEDNESDAY THROUGH FRIDAY...AN ORGANIZED SURFACE AND UPPER LEVEL LOW
IS SHOWN ROLLING THROUGH THE UPPER MS VALLEY. 12Z MODELS CONTINUE TO
VARY IN THE TIMING...TRACK AND STRENGTH OF THIS FEATURE. CONFIDENCE
REMAINS LOW WITH THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS IN THE
WARM ADVECTION REGIME OUT AHEAD...ESPECIALLY FOR THE DAYLIGHT HOURS
WEDNESDAY...WHERE MODELS MAY AGAIN BE OVERESTIMATING THE LOW LEVEL
MOISTURE PROFILES. WILL MAINTAIN CHANCES FOR SHOWERS AND ISOLATED
THUNDERSTORMS FOR WEDNESDAY WITH HIGHS FROM THE UPPER 50S TO MID 60S.
THESE NUMBERS WOULD NOT LIKELY BE WARM ENOUGH IF PRECIPITATION
DOES NOT MATERIALIZE. THUNDERSTORM CHANCES LOOK MUCH GREATER FOR
WEDNESDAY NIGHT ON THE NOSE OF A STRONG LOW LEVEL JET AND ADVANCING
GULF MOISTURE...AND THEN ALSO FOR THURSDAY WHERE THE MODEL CONSENSUS
HAS THE PRIMARY SYSTEM PUSHING THROUGH. LIKELY WORDING FOR
THUNDERSTORMS FOLLOWS THIS PROGRESSION...MAINLY IN THE WEST
OVERNIGHT AND THEN OVER THE ENTIRE AREA THURSDAY. FRIDAY...THE ECMWF
AND GFS HAVE THE SURFACE LOW EXITING OVER THE UPPER GREAT LAKES...
WHICH WOULD LEAD TO A BREEZY AND DRY DAY WITH NEAR NORMAL
TEMPERATURES. HOWEVER...WITH A POTENTIAL FOR THE LOW TO HANG BACK AS
ADVERTISED BY THE OUTLIER CANADIAN MODEL...SLIGHT CHANCES FOR SHOWERS
ARE CARRIED THROUGH THE DAY ACROSS THE NORTH.

NEXT WEEKEND REMAINS A LOW CONFIDENCE PERIOD DUE TO LARGE MODEL
DIFFERENCES. THE ECMWF HAS THE NEXT STRONG SYSTEM MOVING IN FROM THE
SOUTHWEST WITH WIDESPREAD MODERATE RAIN LIKELY AS EARLY AS
SUNDAY...WHILE THE GFS KEEPS A RIDGE OVERHEAD. THIS KEEPS A MENTION
OF RAIN FOR ESPECIALLY SUNDAY WITH TEMPERATURES LIKELY TO BE WELL
BELOW NORMAL EITHER WAY.   11

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1239 PM CDT SUN APR 20 2014

WILL BANK ON ELEVATED SHOWERS AND SOME THUNDERSTORMS REMAINING TO
THE NORTH OF CID AND DBQ THROUGH THIS EVENING IN AREA OF SOME
THTA-E CONVERGENCE AND MID LAYER INSTABILITY. OTHERWISE VFR
CONDITIONS UNTIL LATE TONIGHT WHEN SOME MVFR FOG OF 4-6SM MAY FORM
AFTER 3 AM CDT IN VCNTY OF THE TAF SITES. A FEW SHOWERS AHEAD OF
INCOMING FRONTAL SYSTEM MAY GET IN THE VCNTY OF CID AND DBQ AFTER
2-3AM CDT AS WELL. SCTRD SHOWERS AND A FEW THUNDERSTORMS TO BECOME
MORE WIDESPREAD MON MORNING AHEAD OF SLOW INCOMING FRONTAL
PASSAGE. SOME CIGS LOWERING TO MVFR AS WELL...ALONG WITH ONGOING
4-6SM VSBYS WITH FOG AND SHOWERS MON MORNING. SOUTH TO SOUTHWEST
WINDS OF 10-16 KTS AND HIGHER GUSTS THIS AFTERNOON TO BECOME
LIGHTER TONIGHT INTO EARLY MON MORNING.    ..12..

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&

$$

SYNOPSIS...12
SHORT TERM...12
LONG TERM...11
AVIATION...12






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