Area Forecast Discussion
Issued by NWS Goodland, KS

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FXUS63 KGLD 191803
AFDGLD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GOODLAND KS
1203 PM MDT TUE MAY 19 2015

.UPDATE...
ISSUED AT 1203 PM MDT TUE MAY 19 2015

UPDATE ISSUED TO ACCOUNT FOR SHIFT IN BULK OF REMAINING MODERATE
TO HEAVY PRECIP TO EASTERN PORTIONS OF THE FORECAST AREA. ENTIRE
COMPLEX CONTINUES TO LIFT NORTH AND EAST...AS SOME DRIER AIR
WORKS IN FROM THE SOUTHWEST. NOT ENOUGH TO HINDER -RW AS SOME
FILLING IN OF RADAR IN SW ZONES. HAVE DECREASED POPS IN THESE
AREAS BUT STILL OVERALL 80-100 FOR REST OF DAY. HAVE CONTINUED
MENTION OF ISOLATED TRW THRU THE DAY AS WELL. WINDS HAVE INCREASED
AS WELL WITH DECREASE IN RAIN FROM CENTRAL/WESTERN AREAS...SO HAVE
PUT IN MENTION OF GUSTS TO 40 MPH. NO OTHER CHANGES.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 344 AM MDT TUE MAY 19 2015

LATEST UPPER AIR ANALYSIS SHOW AN UPPER LEVEL SHORT WAVE TROUGH OVER
THE DESERT SOUTHWEST THAT IS CONTINUING TO DEEPEN.  AHEAD OF THE
TROUGH WATER VAPOR IMAGERY SHOWS MOISTURE INCREASING.  AT THE
SURFACE A BACKDOOR COLD FRONT WAS ALMOST HALFWAY THROUGH THE AREA.
LATEST RADAR SHOWS WIDESPREAD RAINFALL OVER EASTERN
COLORADO...GRADUALLY WORKING IT WAY INTO THE TRI-STATE AREA FROM THE
SOUTHWEST.

TODAY THE MAIN QUESTION WILL NOT BE WILL IT RAIN...BUT HOW MUCH RAIN
WILL THE TRI-STATE AREA RECEIVE AS THE SHORT WAVE TROUGH APPROACHES.
THE PRECIPITABLE WATER ON THE 0Z DENVER SOUNDING WAS IN THE 90TH
PERCENTILE OF NORMAL...INDICATING A VERY MOIST ENVIRONMENT AHEAD
OF THE TROUGH MOVING TOWARD THE AREA. LOOKING AT ISENTROPIC LIFT
AND CONDENSATION PRESSURE DEFICITS...THERE IS A CORRIDOR OF ZERO
CONDENSATION PRESSURE DEFICITS WITH THE STRONGEST LIFT JUST AHEAD
OF THE SHORT WAVE TROUGH. IN ADDITION UPSLOPE WIND SPEEDS FROM
305K- 320K ARE 50 KTS OR MORE IN THIS CORRIDOR. THIS STRONG DEEP
ISENTROPIC LIFT IN A SATURATED ENVIRONMENT WITH WELL ABOVE NORMAL
MOISTURE WILL BE HIGHLY CONDUCIVE TO MODERATE OR HEAVY RAINFALL.

AM EXPECTING THE HIGHEST RAINFALL AMOUNTS IN THE MORNING TO BE
MAINLY WEST OF THE KS/CO BORDER WHERE STRONG ISENTROPIC LIFT AND THE
NOSE OF THE LOW LEVEL JET WILL REMAIN THE LONGEST.  DURING THE
AFTERNOON THE STRONG DEEP ISENTROPIC LIFT SHIFTS EAST ACROSS THE
REST OF THE AREA FASTER...WHICH WILL CAUSE RAINFALL AMOUNTS TO BE
LESS EVEN THOUGH THE LIFT IS NOT WEAKENING.  AM NOT ANTICIPATING ANY
FLOODING DESPITE THE MODERATE TO SOMETIMES HEAVY RAINFALL SINCE THE
NARROW CORRIDOR OF DEEP STRONG LIFT IS NOT EXPECTED TO REMAIN
STATIONARY OVER ANY PART OF THE AREA.

700-500MB THETA-E LAPSE RATES INDICATE CONVECTIVE INSTABILITY DUE TO
LAPSE RATES NEAR BUT NOT BELOW ZERO UNTIL LATE MORNING AS THE TROUGH
APPROACHES.  THEREFORE HAVE RAINSHOWERS WITH ISOLATED T-STORMS
MOVING INTO THE AREA FROM THE WEST DURING THE LATE MORNING AND
THROUGH THE AFTERNOON.

DRIER AIR ABOVE 700MB WILL MOVE INTO THE AREA FROM THE WEST THIS
AFTERNOON WITH THE SHORT WAVE TROUGH.  BELOW THIS LEVEL THE
ENVIRONMENT WILL REMAIN SATURATED...WITH SOME WEAK LIFT LINGERING.
SOUNDINGS SHOW THE SATURATED ENVIRONMENT BEING AT LEAST 100MB
DEEP WHICH WOULD BE DEEP ENOUGH TO SUPPORT DRIZZLE. EXPECT THE
RAINFALL TO TRANSITION TO DRIZZLE FROM WEST TO EAST LATE THIS
AFTERNOON AND THROUGH THE EVENING...WITH DRIZZLE OVER THE ENTIRE
AREA BY MIDNIGHT.

WAS INITIALLY A BIT CONCERNED ABOUT THE FORECAST RAINFALL AMOUNTS
BEING SO HIGH AFTER LOOKING AT THE CIPS ANALOGS...WHICH ONLY HAD
HALF AN INCH OR SO ACROSS THE AREA.  HOWEVER COMPARING THE 500MB
HEIGHTS TO WHAT THE MODELS HAVE FOR TODAY...LOOKS LIKE CIPS HAS THE
UPPER LEVEL PATTERN AND RESULTING HIGHER RAINFALL AMOUNTS FURTHER
EAST THAN WHAT WILL ACTUALLY HAPPEN.  CONSIDERING THE VERY HIGH
PRECIPITABLE WATER AMOUNTS WITH THIS TROUGH AND THE STRONG DEEP
LIFT...AM FAIRLY CONFIDENT THE AREA WILL SEE RAINFALL AMOUNTS IN THE
INCH TO INCH AND A HALF RANGE...WITH THE HIGHEST AMOUNTS OVER EAST
CENTRAL COLORADO.

.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 344 AM MDT TUE MAY 19 2015

WEDNESDAY MORNING DRIER AIR BELOW 700MB WILL ADVECT INTO THE AREA
FROM THE WEST BEHIND THE SHORT WAVE TROUGH...CAUSING THE DRIZZLE TO
END FROM WEST TO EAST THROUGH THE DAY.  MAY BE HANGING ONTO THE
DRIZZLE A BIT TOO LONG IN THE AFTERNOON...BUT DO EXPECT THERE TO BE
SOME DRIZZLE LINGERING OVER THE EASTERN PART OF THE AREA DURING THE
LATE MORNING.

DURING THE AFTERNOON A FAIRLY SHALLOW 500MB SHORT WAVE TROUGH MOVES
ACROSS THE AREA BEHIND THE MAIN TROUGH THAT BROUGHT THE RAINFALL.
AM NOT ANTICIPATING ANY STORM ACTIVITY WITH THIS TROUGH PASSAGE DUE
TO A CAPPED ENVIRONMENT.

THURSDAY A SHORT WAVE RIDGE BUILDS OVER THE AREA. LATE THURSDAY
EVENING THE RIDGE BREAKS DOWN SOME AS A SHORT WAVE TROUGH MOVES
THROUGH THE UPPER LEVEL FLOW.  AHEAD OF THE TROUGH THE CONDENSATION
PRESSURE DEFICITS...ESPECIALLY BELOW 700MB...DECLINE.  CURRENTLY
LOOKS LIKE THE STRONGEST LIFT WILL BE OVER THE SOUTHWEST HALF OF THE
AREA WHICH IS WHERE RAINFALL AMOUNTS ARE HIGHEST.

WEDNESDAY AND THURSDAY WARMER AIR WILL MOVE INTO THE AREA ALLOWING
TEMPERATURES TO RISE FROM TODAY.

A LOW PRESSURE SYSTEM WILL CONTINUE TO MOVE OVER THE SOUTHWESTERN
STATES FRIDAY WITH IT MOVING INTO THE FOUR CORNERS REGION SATURDAY
AFTERNOON. RAIN SHOWERS AND THUNDERSTORMS ARE LIKELY FRIDAY
AFTERNOON INTO THE EVENING WITH A 700 MB SHORTWAVE MOVING OVER THE
HIGH PLAINS REGION. SURFACE CAPE AND BULK SHEAR ARE NOT AS
IMPRESSIVE EARLY IN THE DAY FRIDAY BUT THE GFS SHOWS CAPE UP TO 1200
J/KG AND 55 KTS BULK SHEARING ENTRAINING INTO THE REGION LATE FRIDAY
EVENING. SATURDAY WILL CONTINUE TO HAVE THE POTENTIAL FOR
THUNDERSTORMS AS THE LOW PRESSURE CONTINUES TO MOVE CLOSER TO THE
ROCKIES. THE COLD FRONT ASSOCIATED WITH THE LOW PRESSURE SYSTEM WILL
MOVE OVER THE HIGH PLAINS REGION LATE SATURDAY NIGHT INTO SUNDAY
MORNING...ENHANCING THE POTENTIAL FOR SEVERE THUNDERSTORMS TO
DEVELOP ALONG THAT FRONT. THE ECMWF IS MATCHING UP WELL WITH THE
GFS...WHICH GIVES MORE CONFIDENCE FOR POSSIBLE SEVERE WEATHER FRIDAY
THROUGH SUNDAY...BUT WE WILL CONTINUE TO MONITOR FOR A BETTER HANDLE
ON TIMING AND POTENTIAL. THE TWO MODELS DO START TO HAVE DIFFERENCES
EARLY NEXT WEEK...THE ECMWF AND GFS START TO DEVELOP A CLOSED LOW IN
THE NORTHWESTERN STATES BUT THE ECMWF HAS THE LOW MOVING ALONG
WITH THE 500 MB ATMOSPHERIC FLOW...THE GFS DOES NOT. WITH
THAT...MONDAY DOES HAVE A CHANCE FOR PRECIP AS WRAP AROUND
MOISTURE MOVES INTO THE AREA AND THE MODELS DO SHOW A CHANCE FOR
PRECIPITATION TUESDAY.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1130 AM MDT TUE MAY 19 2015

FOR BOTH TAF SITES THRU FORECAST PERIOD...A MIX OF CONDITIONS FROM
MVFR DOWN TO LIFR/VLIFR WILL OCCUR A SLOW PRESSURE TRAVERSES THE
REGION. CEILINGS EXPECTED TO RANGE FROM OVC015 DOWN TO OVC002-005
AT TIMES WITH RAIN/DRIZZLE/FOG REDUCING VISIBILITY TO MAINLY 3-6SM
AT TIMES...BUT 1-2SM POSSIBLE FROM 06Z-14Z WED. WINDS ENE 15-25KTS
THRU 03Z-06Z WED...THEN DOWN TO AROUND 10KTS.


&&

.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&

$$

UPDATE...JN
SHORT TERM...JTL
LONG TERM...JTL/CLT
AVIATION...JN



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